sdp strs fu

Change-Id: Id8ab7f870067d793a2b8934f2cca51cf06ee5dc2

configure.ac

@@ -189,9 +189,11 @@ AC_OUTPUT(
     libosmo-mgcp-client.pc
     include/Makefile
     include/osmocom/Makefile
+    include/osmocom/sdp/Makefile
     include/osmocom/mgcp_client/Makefile
     include/osmocom/mgcp/Makefile
     src/Makefile
+    src/libosmo-sdp/Makefile
     src/libosmo-mgcp-client/Makefile
     src/libosmo-mgcp/Makefile
     src/osmo-mgw/Makefile
@@ -199,6 +201,7 @@ AC_OUTPUT(
     tests/atlocal
     tests/mgcp_client/Makefile
     tests/mgcp/Makefile
+    tests/sdp/Makefile
     doc/Makefile
     doc/examples/Makefile
     doc/manuals/Makefile

include/Makefile.am

@@ -8,6 +8,11 @@ nobase_include_HEADERS = \
 	osmocom/mgcp_client/mgcp_client_endpoint_fsm.h \
 	osmocom/mgcp_client/mgcp_client_fsm.h \
 	osmocom/mgcp_client/mgcp_client_pool.h \
+	osmocom/sdp/fmtp.h \
+	osmocom/sdp/sdp_codec.h \
+	osmocom/sdp/sdp_codec_list.h \
+	osmocom/sdp/sdp_msg.h \
+	osmocom/sdp/sdp_strings.h \
 	$(NULL)
 
 noinst_HEADERS = \

include/osmocom/Makefile.am

@@ -1,4 +1,5 @@
 SUBDIRS = \
+	sdp \
 	mgcp_client \
 	mgcp \
 	$(NULL)

include/osmocom/mgcp/mgcp_codec.h

@@ -13,6 +13,7 @@ struct mgcp_conn_rtp;
 void mgcp_codec_summary(struct mgcp_conn_rtp *conn);
 void mgcp_codec_reset_all(struct mgcp_conn_rtp *conn);
 int mgcp_codec_add(struct mgcp_conn_rtp *conn, int payload_type, const char *audio_name, const struct mgcp_codec_param *param);
+int mgcp_codec_add2(struct mgcp_conn_rtp *conn, int payload_type, const char *audio_name, const char *fmtp);
 int mgcp_codec_decide(struct mgcp_conn_rtp *conn_src, struct mgcp_conn_rtp *conn_dst);
 const struct mgcp_rtp_codec *mgcp_codec_pt_find_by_subtype_name(struct mgcp_conn_rtp *conn,
 								const char *subtype_name, unsigned int match_nr);

include/osmocom/mgcp/mgcp_common.h

@@ -59,7 +59,7 @@ enum mgcp_x_osmo_ign {
 	MGCP_X_OSMO_IGN_CALLID = 1,
 };
 
-/* Codec parameters (communicated via SDP/fmtp) */
+/* Deprecated. Use the new fmtp string instead. */
 struct mgcp_codec_param {
 	bool amr_octet_aligned_present;
 	bool amr_octet_aligned;

include/osmocom/mgcp/mgcp_network.h

@@ -84,8 +84,11 @@ struct mgcp_rtp_codec {
 	char audio_name[64];
 	char subtype_name[64];
 
+	/* Deprecated. Use the new fmtp string instead. */
 	bool param_present;
 	struct mgcp_codec_param param;
+
+	char fmtp[256];
 };
 
 /* 'mgcp_rtp_end': basically a wrapper around the RTP+RTCP ports */

include/osmocom/mgcp_client/mgcp_client.h

@@ -77,6 +77,9 @@ struct ptmap {
 
 	/*! payload type number (96-127) */
 	unsigned int pt;
+
+	/*! the MGCP 'a=fmtp:N <...>' string, e.g. "mode-set=1,2,3;octet-align=0". */
+	char fmtp[256];
 };
 
 int ptmap_cmp(const struct ptmap *a, const struct ptmap *b);

include/osmocom/mgcp_client/mgcp_client_fsm.h

@@ -57,10 +57,11 @@ struct mgcp_conn_peer {
 	 * address is set. If != MGCP_CONN_NONE, force this conn mode. */
 	enum mgcp_connection_mode conn_mode;
 
-	/*! If the codec requires additional format parameters (fmtp), those cann be set here, see also
-	 * mgcp_common.h */
-	bool param_present;
-	struct mgcp_codec_param param;
+	/*! Deprectated, use ptmap[].fmtp instead.
+	 * Global codec params. In case the codec requires additional format parameters (fmtp), those can be set
+	 * here, see also mgcp_common.h. The format parameters will be applied on all codecs where applicable. */
+	bool param_present OSMO_DEPRECATED_OUTSIDE_LIBOSMOMGCPCLIENT("use ptmap[].fmtp instead");
+	struct mgcp_codec_param param OSMO_DEPRECATED_OUTSIDE_LIBOSMOMGCPCLIENT("use ptmap[].fmtp instead");
 };
 
 struct osmo_fsm_inst *mgcp_conn_create(struct mgcp_client *mgcp, struct osmo_fsm_inst *parent_fi, uint32_t parent_term_evt,

include/osmocom/sdp/Makefile.am

@@ -0,0 +1,3 @@
+noinst_HEADERS = \
+	sdp_internal.h \
+	$(NULL)

include/osmocom/sdp/fmtp.h

@@ -0,0 +1,34 @@
+/* Public API for codec management in SDP messages: managing SDP fmtp strings. */
+/*
+ * (C) 2024 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ *
+ * Author: Neels Janosch Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#pragma once
+
+#include <stddef.h>
+#include <stdbool.h>
+#include <stdint.h>
+
+bool osmo_sdp_fmtp_get_val(char *val, size_t val_size, const char *fmtp, const char *option_name);
+int64_t osmo_sdp_fmtp_get_int(const char *fmtp, const char *option_name, int64_t default_value);
+
+bool osmo_sdp_fmtp_amr_is_octet_aligned(const char *fmtp);
+bool osmo_sdp_fmtp_amr_match(const char *a, const char *b);

include/osmocom/sdp/sdp_codec.h

@@ -0,0 +1,126 @@
+/* Public API for codec management in SDP messages. */
+/*
+ * (C) 2024 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ *
+ * Author: Neels Janosch Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#pragma once
+
+#include <osmocom/core/linuxlist.h>
+#include <osmocom/core/talloc.h>
+
+/* RFC-8866 5.14 and 6.6.
+ *
+ * Represent the items describing an SDP codec entry, as in:
+ *
+ *   m=audio 1234 RTP/AVP <payload_type>
+ *   a=rtpmap:<payload_type> <encoding-name>/<clock-rate>
+ *   a=fmtp:<payload_type> <fmtp>
+ *
+ * For example:
+ *
+ *   m=audio 1234 RTP/AVP 98
+ *   a=rtpmap:98 AMR/8000
+ *   a=fmtp:98 octet-align=1;mode-set=0,2,4,7
+ */
+struct osmo_sdp_codec {
+	/* Payload type number ("payload-type"), like 3 for GSM-FR. Limited to 0..127. */
+	int8_t payload_type;
+
+	/* Encoding name like "GSM", "AMR", "GSM-EFR".
+	 *
+	 * RFC-8866 defines no length limit on the encoding name. This API leaves it up to the caller to provide
+	 * sufficient space, via the SDP_SIZES_* definitions.
+	 *
+	 * encoding-name = token
+	 * token = 1*(token-char)
+	 * token-char = ALPHA / DIGIT
+	 *                    / "!" / "#" / "$" / "%" / "&"
+	 *                    / "'" ; (single quote)
+	 *                    / "*" / "+" / "-" / "." / "^" / "_"
+	 *                    / "`" ; (Grave accent)
+	 */
+	char *encoding_name;
+
+	/* Samplerate ("clock-rate"), usually 8000 for GSM. */
+	unsigned int rate;
+
+	/* Codec parameters as supplied in SDP line 'a=fmtp:<payload-type> <format-specific-params>'. This holds only
+	 * the 'format-specific-params' bytestring. For example, for SDP line 'a=fmtp:123 param1=val1;param2=val2', this
+	 * holds only the , "param1=val1;param2=val2" part. For the buffer size, see fmtp_size. */
+	char *fmtp;
+
+	/* Entry used by osmo_sdp_codec_list. */
+	struct llist_head entry;
+
+	/* For future extension, always set to false. */
+	bool v2;
+};
+
+struct osmo_sdp_codec *osmo_sdp_codec_alloc(void *ctx);
+
+int osmo_sdp_codec_set(struct osmo_sdp_codec *c,
+		       int8_t payload_type, const char *encoding_name, unsigned int rate, const char *fmtp);
+int osmo_sdp_codec_set_encoding_name(struct osmo_sdp_codec *c, const char *encoding_name);
+int osmo_sdp_codec_set_fmtp(struct osmo_sdp_codec *c, const char *fmtp);
+
+bool osmo_sdp_codec_is_set(const struct osmo_sdp_codec *a);
+
+int osmo_sdp_codec_to_str_buf(char *buf, size_t buflen, const struct osmo_sdp_codec *codec);
+char *osmo_sdp_codec_to_str_c(void *ctx, const struct osmo_sdp_codec *codec);
+
+int osmo_sdp_codec_from_str(struct osmo_sdp_codec *dst, const char *str, int str_len);
+
+enum osmo_sdp_cmp {
+	OSMO_SDP_CMP_IGNORE = 0,
+	OSMO_SDP_CMP_EQUIVALENT,
+	OSMO_SDP_CMP_EXACT,
+};
+
+/*! Indicate how to match SDP codecs to various osmo_sdp_*() functions.
+ * Callers may define own flags, or use predefined instances:
+ * osmo_sdp_codec_cmp_exact, osmo_sdp_codec_cmp_equivalent, ...
+ *
+ * For example, to trigger some action if any item has changed, set all items to true / OSMO_SDP_CMP_EXACT (see
+ * osmo_sdp_codec_cmp_exact).
+ * To find codecs that are the same between two SDP sessions, set payload_type=false and fmtp=OSMO_SDP_CMP_EQUIVALENT
+ * (see osmo_sdp_codec_cmp_equivalent).
+ * To just list all contained "AMR" codecs, set only encoding_name=true (see osmo_sdp_codec_cmp_name).
+ */
+struct osmo_sdp_codec_cmp_flags {
+	/*! true = compare payload type numbers 1:1; false = ignore. */
+	bool payload_type;
+	/*! true = compare encoding_name 1:1; false = ignore. */
+	bool encoding_name;
+	/*! true = compare rate 1:1; false = ignore. */
+	bool rate;
+	/*! OSMO_SDP_CMP_IGNORE = ignore fmtp;
+	 * OSMO_SDP_CMP_EQUIVALENT = use osmo_sdp_fmtp_amr_match() for AMR, otherwise compare 1:1;
+	 * OSMO_SDP_CMP_EXACT = compare 1:1.
+	 */
+	enum osmo_sdp_cmp fmtp;
+};
+
+extern const struct osmo_sdp_codec_cmp_flags osmo_sdp_codec_cmp_exact;
+extern const struct osmo_sdp_codec_cmp_flags osmo_sdp_codec_cmp_equivalent;
+extern const struct osmo_sdp_codec_cmp_flags osmo_sdp_codec_cmp_name;
+
+int osmo_sdp_codec_cmp(const struct osmo_sdp_codec *a, const struct osmo_sdp_codec *b,
+		       const struct osmo_sdp_codec_cmp_flags *cmp);

include/osmocom/sdp/sdp_codec_list.h

@@ -0,0 +1,69 @@
+/* Public API for codec management in SDP messages: list of struct osmo_sdp_codec. */
+/*
+ * (C) 2024 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ *
+ * Author: Neels Janosch Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#pragma once
+
+#include <osmocom/sdp/sdp_codec.h>
+
+struct osmo_sdp_codec_list {
+	struct llist_head list;
+
+	/* For future extension, always set to false. */
+	bool v2;
+};
+
+struct osmo_sdp_codec_list *osmo_sdp_codec_list_alloc(void *ctx);
+void osmo_sdp_codec_list_free_items(struct osmo_sdp_codec_list *codec_list);
+
+int8_t osmo_sdp_codec_list_get_unused_dyn_pt_nr(const struct osmo_sdp_codec_list *codec_list, int8_t suggest_pt_nr);
+
+struct osmo_sdp_codec *osmo_sdp_codec_list_add_empty(struct osmo_sdp_codec_list *codec_list);
+struct osmo_sdp_codec *osmo_sdp_codec_list_add(struct osmo_sdp_codec_list *codec_list,
+					       const struct osmo_sdp_codec *codec,
+					       const struct osmo_sdp_codec_cmp_flags *once, bool pick_unused_pt_nr);
+
+int osmo_sdp_codec_list_remove(struct osmo_sdp_codec_list *codec_list, const struct osmo_sdp_codec *codec,
+			       const struct osmo_sdp_codec_cmp_flags *cmpf);
+void osmo_sdp_codec_list_remove_entry(struct osmo_sdp_codec *codec);
+
+int osmo_sdp_codec_list_to_str_buf(char *buf, size_t buflen, const struct osmo_sdp_codec_list *codec_list, bool summarize);
+char *osmo_sdp_codec_list_to_str_c(void *ctx, const struct osmo_sdp_codec_list *codec_list, bool summarize);
+
+struct osmo_sdp_codec *osmo_sdp_codec_list_first(const struct osmo_sdp_codec_list *list);
+int osmo_sdp_codec_list_move_to_first(struct osmo_sdp_codec_list *codec_list, const struct osmo_sdp_codec *codec,
+				      const struct osmo_sdp_codec_cmp_flags *cmpf);
+
+#define osmo_sdp_codec_list_foreach(STRUCT_SDP_CODEC_P, SDP_CODEC_LIST) \
+	llist_for_each_entry(STRUCT_SDP_CODEC_P, &(SDP_CODEC_LIST)->list, entry)
+#define osmo_sdp_codec_list_foreach_safe(STRUCT_SDP_CODEC_P, SAFE_P, SDP_CODEC_LIST) \
+	llist_for_each_entry_safe(STRUCT_SDP_CODEC_P, SAFE_P, &(SDP_CODEC_LIST)->list, entry)
+
+int osmo_sdp_codec_list_cmp(const struct osmo_sdp_codec_list *a, const struct osmo_sdp_codec_list *b,
+			    const struct osmo_sdp_codec_cmp_flags *cmpf);
+
+void osmo_sdp_codec_list_intersection(struct osmo_sdp_codec_list *dst, const struct osmo_sdp_codec_list *other,
+				      const struct osmo_sdp_codec_cmp_flags *cmpf,
+				      bool translate_payload_type_numbers);
+
+struct osmo_sdp_codec *osmo_sdp_codec_list_by_payload_type(struct osmo_sdp_codec_list *codec_list, int8_t payload_type);
+bool osmo_sdp_codec_list_is_empty(const struct osmo_sdp_codec_list *codec_list);

include/osmocom/sdp/sdp_internal.h

@@ -0,0 +1,11 @@
+/* Internal header for non-public API shared across .c files */
+#pragma once
+
+struct token {
+	const char *start;
+	const char *end;
+};
+
+/* Copy a string from [start,end[, return as talloc allocated under ctx in *dst.
+ * If *dst is non-NULL, talloc_free(*dst) first. */
+void token_copy(void *ctx, char **dst, const struct token *t);

include/osmocom/sdp/sdp_msg.h

@@ -0,0 +1,98 @@
+/* Public API for SDP message encoding and decoding */
+/*
+ * (C) 2024 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ *
+ * Author: Neels Janosch Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#pragma once
+
+#include <osmocom/core/sockaddr_str.h>
+
+#include <osmocom/sdp/sdp_codec.h>
+#include <osmocom/sdp/sdp_codec_list.h>
+
+/* Media Direction Attributes "a=recvonly", "a=sendrecv", "a=sendonly", "a=inactive" RFC-8866 6.7. */
+enum osmo_sdp_media_direcion_e {
+	OSMO_SDP_MDIR_UNSET = 0,
+	OSMO_SDP_MDIR_RECVONLY = 1,
+	OSMO_SDP_MDIR_SENDRECV = 2,
+	OSMO_SDP_MDIR_SENDONLY = 3,
+	OSMO_SDP_MDIR_INACTIVE = 4,
+};
+
+/* Session Description Protocol (SDP) message, RFC-8866. */
+struct osmo_sdp_msg {
+	/* 5.2 Origin ("o="). */
+	struct {
+		struct osmo_sockaddr_str addr;
+		char *username;
+		char *sess_id;
+		char *sess_version;
+	} origin;
+
+	/* 5.3 Session Name ("s="). */
+	char *session_name;
+
+	/* 5.7 Connection Information ("c=") and port from 5.14 Media Descriptions ("m="). */
+	struct osmo_sockaddr_str rtp;
+
+	/* 5.9. Time Active ("t="). */
+	struct {
+		int64_t start;
+		int64_t stop;
+	} time_active;
+
+	/* 6.4 "a=ptime:<val>". */
+	unsigned int ptime;
+
+	/* 6.7 "a=sendrecv"... */
+	enum osmo_sdp_media_direcion_e media_direction;
+
+	/* List of codecs defined in the SDP message.
+	 * This should not be NULL -- osmo_sdp_msg_alloc() returns an empty osmo_sdp_codec_list instance, ready for
+	 * adding codecs.
+	 * Combination of:
+	 * - payload_type numbers from 5.14 Media Descriptions ("m="),
+	 * - 6.6 "a=rtpmap",
+	 * - 6.15 Format Parameters "a=fmtp".
+	 */
+	struct osmo_sdp_codec_list *codecs;
+
+	/* For future extension, always set to false. */
+	bool v2;
+};
+
+struct osmo_sdp_err {
+	int rc;
+	/* Point at the position that caused the error, in the src string. */
+	const char *at_input_str;
+	/* Nr of characters at *src_str that are relevant to the error. */
+	size_t at_input_str_len;
+};
+
+struct osmo_sdp_msg *osmo_sdp_msg_alloc(void *ctx);
+
+struct osmo_sdp_msg *osmo_sdp_msg_decode(void *ctx, const char *src, struct osmo_sdp_err *err);
+
+int osmo_sdp_msg_encode_buf(char *dst, size_t dst_size, const struct osmo_sdp_msg *sdp);
+char *osmo_sdp_msg_encode_c(void *ctx, const struct osmo_sdp_msg *sdp);
+
+int osmo_sdp_msg_to_str_buf(char *buf, size_t buflen, const struct osmo_sdp_msg *sdp, bool summarize);
+char *osmo_sdp_msg_to_str_c(void *ctx, const struct osmo_sdp_msg *sdp, bool summarize);

include/osmocom/sdp/sdp_strings.h

@@ -0,0 +1,39 @@
+/* Central definition of string tokens used for parsing and composing SDP messages */
+#pragma once
+
+#define OSMO_SDP_STR_MEDIA "m"
+#define OSMO_SDP_STR_ATTRIB "a"
+#define OSMO_SDP_STR_TIME_ACTIVE "t"
+
+#define OSMO_SDP_STR_RTPMAP "rtpmap"
+#define OSMO_SDP_STR_FMTP "fmtp"
+#define OSMO_SDP_STR_PTIME "ptime"
+
+/*! "a=foo:" */
+#define OSMO_SDP_A_PREFIX(STR) OSMO_SDP_STR_ATTRIB "=" STR ":"
+
+/*! "a=fmtp:" */
+#define OSMO_SDP_STR_A_FMTP OSMO_SDP_A_PREFIX(OSMO_SDP_STR_FMTP)
+
+/* Media Direction Attributes "a=recvonly", "a=sendrecv", "a=sendonly", "a=inactive" RFC-8866 6.7. */
+#define OSMO_SDP_STR_RECVONLY "recvonly"
+#define OSMO_SDP_STR_SENDRECV "sendrecv"
+#define OSMO_SDP_STR_SENDONLY "sendonly"
+#define OSMO_SDP_STR_INACTIVE "inactive"
+
+/* AMR related tokens */
+
+#define OSMO_SDP_STR_AMR_OCTET_ALIGN "octet-align"
+
+/*! "octet-align=1" */
+#define OSMO_SDP_STR_AMR_OCTET_ALIGN_1  OSMO_SDP_STR_AMR_OCTET_ALIGN "=1"
+
+/*! "octet-align=0".
+ * According to spec [1], "octet-align=0" is identical to omitting 'octet-align' entirely. In Osmocom practice, whether
+ * or not "octet-align=0" is present can make a big difference for osmo-mgw versions 1.12 and older, which do not heed
+ * [1].
+ *
+ * spec [1]: RFC4867, see details in description of osmo_sdp_fmtp_amr_is_octet_aligned().
+ */
+#define OSMO_SDP_STR_AMR_OCTET_ALIGN_0  OSMO_SDP_STR_AMR_OCTET_ALIGN "=0"
+

src/Makefile.am

@@ -15,6 +15,7 @@ AM_CFLAGS = \
 
 # Libraries
 SUBDIRS = \
+	libosmo-sdp \
 	libosmo-mgcp-client \
 	libosmo-mgcp \
 	$(NULL)

src/libosmo-mgcp-client/Makefile.am

@@ -40,6 +40,7 @@ libosmo_mgcp_client_la_LDFLAGS = \
 	$(NULL)
 
 libosmo_mgcp_client_la_LIBADD = \
+	$(top_builddir)/src/libosmo-sdp/libosmo-sdp.la \
 	$(LIBOSMOCORE_LIBS) \
 	$(LIBOSMOVTY_LIBS) \
 	$(NULL)

src/libosmo-mgcp-client/mgcp_client.c

@@ -29,6 +29,7 @@
 
 #include <osmocom/mgcp_client/mgcp_client.h>
 #include <osmocom/mgcp_client/mgcp_client_internal.h>
+#include <osmocom/sdp/sdp_strings.h>
 
 #include <osmocom/abis/e1_input.h>
 
@@ -388,11 +389,12 @@ static int mgcp_parse_audio_ptime_rtpmap(struct mgcp_response *r, const char *li
 {
 	unsigned int pt;
 	unsigned int i;
-	char codec_resp[64];
+	char codec_resp[256];
 	int rc;
 
-#define A_PTIME "a=ptime:"
-#define A_RTPMAP "a=rtpmap:"
+#define A_PTIME OSMO_SDP_A_PREFIX(OSMO_SDP_STR_PTIME)
+#define A_RTPMAP OSMO_SDP_A_PREFIX(OSMO_SDP_STR_RTPMAP)
+#define A_FMTP OSMO_SDP_A_PREFIX(OSMO_SDP_STR_FMTP)
 
 	if (osmo_str_startswith(line, A_PTIME)) {
 		if (sscanf(line, A_PTIME "%u", &r->ptime) != 1) {
@@ -401,7 +403,7 @@ static int mgcp_parse_audio_ptime_rtpmap(struct mgcp_response *r, const char *li
 			return -EINVAL;
 		}
 	} else if (osmo_str_startswith(line, A_RTPMAP)) {
-		if (sscanf(line, A_RTPMAP "%d %63s", &pt, codec_resp) != 2) {
+		if (sscanf(line, A_RTPMAP "%d %255s", &pt, codec_resp) != 2) {
 			LOGP(DLMGCP, LOGL_ERROR,
 			     "Failed to parse SDP parameter, invalid rtpmap: %s\n", osmo_quote_str(line, -1));
 			return -EINVAL;
@@ -440,6 +442,42 @@ static int mgcp_parse_audio_ptime_rtpmap(struct mgcp_response *r, const char *li
 			.codec = rc,
 		};
 		r->ptmap_len++;
+
+	} else if (osmo_str_startswith(line, A_FMTP)) {
+		if (sscanf(line, A_FMTP "%d %255s", &pt, codec_resp) != 2) {
+			LOGP(DLMGCP, LOGL_ERROR,
+			     "Failed to parse SDP parameter, invalid fmtp: %s\n", osmo_quote_str(line, -1));
+			return -EINVAL;
+		}
+
+		/* Earlier, a line like "m=audio 16002 RTP/AVP 98 112 3" established the desired order of payloads, now
+		 * enrich it with actual codec information provided by "a=rtpmap:..." entries.
+		 * For each, find the entry with the right pt number and add the info there. */
+
+		for (i = 0; i < r->ptmap_len; i++) {
+			if (r->ptmap[i].pt != pt)
+				continue;
+			OSMO_STRLCPY_ARRAY(r->ptmap[r->ptmap_len].fmtp, codec_resp);
+			return 0;
+		}
+
+		/* No entry was found. This is an error in the MGCP protocol, but let's just add another entry
+		 * anyway, to not make it look like it was never there. */
+		LOGP(DLMGCP, LOGL_ERROR,
+		     "error in MGCP message: 'a=fmtp:%u' has no matching entry in 'm=audio ... %u'\n",
+		     pt, pt);
+		if (r->ptmap_len >= ARRAY_SIZE(r->ptmap)) {
+			LOGP(DLMGCP, LOGL_ERROR,
+			     "cannot parse all codecs: can only store up to %zu rtpmap entries.\n",
+			     ARRAY_SIZE(r->ptmap));
+			return -ENOSPC;
+		}
+		r->ptmap[r->ptmap_len] = (struct ptmap){
+			.pt = pt,
+			.codec = -1,
+		};
+		OSMO_STRLCPY_ARRAY(r->ptmap[r->ptmap_len].fmtp, codec_resp);
+		r->ptmap_len++;
 	}
 
 	return 0;
@@ -1382,13 +1420,20 @@ static int add_sdp(struct msgb *msg, struct mgcp_msg *mgcp_msg, struct mgcp_clie
 	MSGB_PRINTF_OR_RET("\r\n");
 
 	/* Add optional codec parameters (fmtp) */
-	if (mgcp_msg->param_present) {
-		for (i = 0; i < mgcp_msg->ptmap_len; i++) {
-			/* The following is only applicable for AMR */
-			if (mgcp_msg->ptmap[i].codec != CODEC_AMR_8000_1
-			    && mgcp_msg->ptmap[i].codec != CODEC_AMRWB_16000_1)
-				continue;
+	for (i = 0; i < mgcp_msg->ptmap_len; i++) {
+		/* Add fmtp string, if any is set. */
+		if (mgcp_msg->ptmap[i].fmtp[0]) {
+			MSGB_PRINTF_OR_RET("a=fmtp:%u %s\r\n", mgcp_msg->ptmap[i].pt, mgcp_msg->ptmap[i].fmtp);
+			continue;
+		}
+
+		/* LEGACY COMPAT. Fill in fmtp with the legacy mgcp_msg->param, if any, when no individual fmtp is set
+		 * on the codec. We only ever supported AMR fmtp in mgcp_msg->param. */
+		if (mgcp_msg->param_present
+		    && (mgcp_msg->ptmap[i].codec == CODEC_AMR_8000_1
+			|| mgcp_msg->ptmap[i].codec == CODEC_AMRWB_16000_1)) {
 			pt = mgcp_msg->ptmap[i].pt;
+
 			if (mgcp_msg->param.amr_octet_aligned_present && mgcp_msg->param.amr_octet_aligned)
 				MSGB_PRINTF_OR_RET("a=fmtp:%u octet-align=1\r\n", pt);
 			else if (mgcp_msg->param.amr_octet_aligned_present && !mgcp_msg->param.amr_octet_aligned)
@@ -1626,5 +1671,8 @@ int ptmap_cmp(const struct ptmap *a, const struct ptmap *b)
 	rc = OSMO_CMP(a->codec, b->codec);
 	if (rc)
 		return rc;
-	return OSMO_CMP(a->pt, b->pt);
+	rc = OSMO_CMP(a->pt, b->pt);
+	if (rc)
+		return rc;
+	return strcmp(a->fmtp, b->fmtp);
 }

src/libosmo-mgcp/Makefile.am

@@ -19,15 +19,15 @@ AM_LDFLAGS = \
 	$(COVERAGE_LDFLAGS) \
 	$(NULL)
 
-noinst_LIBRARIES = \
-	libosmo-mgcp.a \
+noinst_LTLIBRARIES = \
+	libosmo-mgcp.la \
 	$(NULL)
 
 noinst_HEADERS = \
 	g711common.h \
 	$(NULL)
 
-libosmo_mgcp_a_SOURCES = \
+libosmo_mgcp_la_SOURCES = \
 	mgcp_protocol.c \
 	mgcp_network.c \
 	mgcp_vty.c \
@@ -43,3 +43,13 @@ libosmo_mgcp_a_SOURCES = \
 	mgcp_e1.c \
 	mgcp_iuup.c \
 	$(NULL)
+
+libosmo_mgcp_la_LIBADD = \
+	$(top_builddir)/src/libosmo-sdp/libosmo-sdp.la \
+	$(LIBOSMOCORE_LIBS) \
+	$(LIBOSMOGSM_LIBS) \
+	$(LIBOSMOVTY_LIBS) \
+	$(LIBOSMONETIF_LIBS) \
+	$(LIBOSMOABIS_LIBS) \
+	$(LIBOSMOTRAU_LIBS) \
+	$(NULL)

src/libosmo-mgcp/mgcp_codec.c

@@ -24,6 +24,10 @@
 #include <osmocom/mgcp/mgcp_endp.h>
 #include <osmocom/mgcp/mgcp_trunk.h>
 #include <osmocom/mgcp/mgcp_codec.h>
+
+#include <osmocom/sdp/sdp_strings.h>
+#include <osmocom/sdp/fmtp.h>
+
 #include <errno.h>
 
 /* Helper function to dump codec information of a specified codec to a printable
@@ -116,9 +120,9 @@ void mgcp_codec_reset_all(struct mgcp_conn_rtp *conn)
  *  \param[out] conn related rtp-connection.
  *  \param[in] payload_type codec type id (e.g. 3 for GSM, -1 when undefined).
  *  \param[in] audio_name audio codec name, in uppercase (e.g. "GSM/8000/1").
- *  \param[in] param optional codec parameters (set to NULL when unused).
+ *  \param[in] fmtp optional codec parameters (set to NULL when unused).
  *  \returns 0 on success, -EINVAL on failure. */
-int mgcp_codec_add(struct mgcp_conn_rtp *conn, int payload_type, const char *audio_name, const struct mgcp_codec_param *param)
+int mgcp_codec_add2(struct mgcp_conn_rtp *conn, int payload_type, const char *audio_name, const char *fmtp)
 {
 	int rate;
 	int channels;
@@ -261,12 +265,16 @@ int mgcp_codec_add(struct mgcp_conn_rtp *conn, int payload_type, const char *aud
 		}
 	}
 
-	/* Copy over optional codec parameters */
-	if (param) {
-		codec->param = *param;
-		codec->param_present = true;
-	} else
-		codec->param_present = false;
+	if (fmtp) {
+		OSMO_STRLCPY_ARRAY(codec->fmtp, fmtp);
+		if (strlen(codec->fmtp) != strlen(fmtp)) {
+			LOGP(DLMGCP, LOGL_ERROR, "fmtp too long: %zu > %zu\n", strlen(fmtp), strlen(codec->fmtp));
+			/* let's just hope what is there is still useful, worst case the call's audio doesn't work */
+		}
+	}
+
+	/* legacy */
+	codec->param_present = false;
 
 	conn->end.codecs_assigned++;
 	return 0;
@@ -276,23 +284,33 @@ error:
 	return -EINVAL;
 }
 
-/* Return true if octet-aligned is set in the given codec. Default to octet-aligned=0, i.e. bandwidth-efficient mode.
- * See RFC4867 "RTP Payload Format for AMR and AMR-WB" sections "8.1. AMR Media Type Registration" and "8.2. AMR-WB
- * Media Type Registration":
- *
- *    octet-align: Permissible values are 0 and 1.  If 1, octet-aligned
- *                 operation SHALL be used.  If 0 or if not present,
- *                 bandwidth-efficient operation is employed.
- *
- * https://tools.ietf.org/html/rfc4867
- */
+/*! Legacy compat, use mgcp_codec_add2() instead to be able to pass any fmtp besides AMR octet-align=1.
+ * Add codec configuration depending on payload type and/or codec name. This
+ *  function uses the input parameters to extrapolate the full codec information.
+ *  \param[out] codec configuration (caller provided memory).
+ *  \param[out] conn related rtp-connection.
+ *  \param[in] payload_type codec type id (e.g. 3 for GSM, -1 when undefined).
+ *  \param[in] audio_name audio codec name, in uppercase (e.g. "GSM/8000/1").
+ *  \param[in] param optional codec parameters (set to NULL when unused).
+ *  \returns 0 on success, -EINVAL on failure. */
+int mgcp_codec_add(struct mgcp_conn_rtp *conn, int payload_type, const char *audio_name, const struct mgcp_codec_param *param)
+{
+	const char *fmtp = NULL;
+	if (param && param->amr_octet_aligned_present)
+		fmtp = (param->amr_octet_aligned ? OSMO_SDP_STR_AMR_OCTET_ALIGN_1 : OSMO_SDP_STR_AMR_OCTET_ALIGN_0);
+
+	return mgcp_codec_add2(conn, payload_type, audio_name, fmtp);
+}
+
 bool mgcp_codec_amr_is_octet_aligned(const struct mgcp_rtp_codec *codec)
 {
-	if (!codec->param_present)
-		return false;
-	if (!codec->param.amr_octet_aligned_present)
-		return false;
-	return codec->param.amr_octet_aligned;
+	/* Legacy */
+	if (!codec->fmtp[0]
+	    && codec->param_present
+	    && codec->param.amr_octet_aligned_present)
+		return codec->param.amr_octet_aligned;
+
+	return osmo_sdp_fmtp_amr_is_octet_aligned(codec->fmtp);
 }
 
 /* Compare two codecs, all parameters must match up */
@@ -471,13 +489,13 @@ int mgcp_codec_decide(struct mgcp_conn_rtp *conn_src, struct mgcp_conn_rtp *conn
 /* Check if the codec has a specific AMR mode (octet-aligned or bandwith-efficient) set. */
 bool mgcp_codec_amr_align_mode_is_indicated(const struct mgcp_rtp_codec *codec)
 {
-	if (codec->param_present == false)
-		return false;
-	if (!codec->param.amr_octet_aligned_present)
-		return false;
-	if (strcmp(codec->subtype_name, "AMR") != 0)
-		return false;
-	return true;
+	if (!codec->fmtp[0]) {
+		/* Legacy */
+		return codec->param_present && codec->param.amr_octet_aligned_present;
+	}
+
+	/* Just check for presence, not the actual value. */
+	return osmo_sdp_fmtp_get_val(NULL, 0, codec->fmtp, OSMO_SDP_STR_AMR_OCTET_ALIGN);
 }
 
 /* Find the payload type number configured for a specific codec by SDP.

src/libosmo-mgcp/mgcp_network.c

@@ -1207,11 +1207,12 @@ int mgcp_send(struct mgcp_endpoint *endp, int is_rtp, struct osmo_sockaddr *addr
 		if (mgcp_conn_rtp_is_iuup(conn_dst) || mgcp_conn_rtp_is_iuup(conn_src)) {
 			/* the iuup code will correctly transform to the correct AMR mode */
 		} else if (mgcp_codec_amr_align_mode_is_indicated(conn_dst->end.codec)) {
-			rc = amr_oa_bwe_convert(endp, msg, conn_dst->end.codec->param.amr_octet_aligned);
+			bool oa = mgcp_codec_amr_is_octet_aligned(conn_dst->end.codec);
+			rc = amr_oa_bwe_convert(endp, msg, oa);
 			if (rc < 0) {
 				LOGPENDP(endp, DRTP, LOGL_ERROR,
 					 "Error in AMR octet-aligned <-> bandwidth-efficient mode conversion (target=%s)\n",
-					 conn_dst->end.codec->param.amr_octet_aligned ? "octet-aligned" : "bandwidth-efficient");
+					 oa ? "octet-aligned" : "bandwidth-efficient");
 				msgb_free(msg);
 				return rc;
 			}
@@ -1564,16 +1565,18 @@ static int rx_rtp(struct msgb *msg)
 	if (mc->proto == MGCP_PROTO_RTP
 	    && conn_src->end.codec
 	    && mgcp_codec_amr_align_mode_is_indicated(conn_src->end.codec)) {
+		bool src_oa;
 		/* Make sure that the incoming AMR frame format matches the frame format that the call agent has
 		 * communicated via SDP when the connection was created/modfied. */
 		int oa = amr_oa_check((char*)msgb_data(msg), msgb_length(msg));
 		if (oa < 0)
 			goto out_free;
-		if (((bool)oa) != conn_src->end.codec->param.amr_octet_aligned) {
+		src_oa = mgcp_codec_amr_is_octet_aligned(conn_src->end.codec);
+		if (((bool)oa) != src_oa) {
 			LOG_CONN_RTP(conn_src, LOGL_NOTICE,
 				     "rx_rtp(%u bytes): Expected RTP AMR octet-aligned=%u but got octet-aligned=%u."
 				     " check the config of your call-agent!\n",
-				     msgb_length(msg), conn_src->end.codec->param.amr_octet_aligned, oa);
+				     msgb_length(msg), src_oa, oa);
 			goto out_free;
 		}
 	}

src/libosmo-mgcp/mgcp_protocol.c

@@ -1083,17 +1083,6 @@ mgcp_header_done:
 
 	mgcp_rtp_end_config(endp, 0, &conn->end);
 
-	/* check connection mode setting */
-	if (conn->conn->mode != MGCP_CONN_LOOPBACK
-	    && conn->conn->mode != MGCP_CONN_RECV_ONLY
-	    && osmo_sockaddr_port(&conn->end.addr.u.sa) == 0) {
-		LOGPCONN(_conn, DLMGCP, LOGL_ERROR,
-			 "CRCX: selected connection mode type requires an opposite end!\n");
-		error_code = 527;
-		rate_ctr_inc(rate_ctr_group_get_ctr(rate_ctrs, MGCP_CRCX_FAIL_NO_REMOTE_CONN_DESC));
-		goto error2;
-	}
-
 	/* Find a local address for conn based on policy and initial SDP remote
 	   information, then find a free port for it */
 	if (mgcp_get_local_addr(conn->end.local_addr, conn) < 0) {
@@ -1131,6 +1120,7 @@ mgcp_header_done:
 
 	LOGPCONN(_conn, DLMGCP, LOGL_NOTICE,
 		 "CRCX: connection successfully created\n");
+
 	rate_ctr_inc(rate_ctr_group_get_ctr(rate_ctrs, MGCP_CRCX_SUCCESS));
 	mgcp_endp_update(endp);
 
@@ -1295,17 +1285,6 @@ mgcp_header_done:
 	if (conn->type == MGCP_RTP_DEFAULT && strcmp(conn->end.codec->subtype_name, "VND.3GPP.IUFP") == 0)
 		rc = mgcp_conn_iuup_init(conn);
 
-	/* check connection mode setting */
-	if (conn->conn->mode != MGCP_CONN_LOOPBACK
-	    && conn->conn->mode != MGCP_CONN_RECV_ONLY
-	    && !mgcp_rtp_end_remote_addr_available(&conn->end)) {
-		LOGPCONN(conn->conn, DLMGCP, LOGL_ERROR,
-			 "MDCX: selected connection mode type requires an opposite end!\n");
-		error_code = 527;
-		rate_ctr_inc(rate_ctr_group_get_ctr(rate_ctrs, MGCP_MDCX_FAIL_NO_REMOTE_CONN_DESC));
-		goto error3;
-	}
-
 	if (mgcp_conn_rtp_is_osmux(conn)) {
 		OSMO_ASSERT(conn->osmux.local_cid_allocated);
 		if (remote_osmux_cid < -1) {

src/libosmo-mgcp/mgcp_sdp.c

@@ -35,6 +35,9 @@
 #include <osmocom/mgcp/mgcp_sdp.h>
 #include <osmocom/mgcp/mgcp_protocol.h>
 
+#include <osmocom/sdp/fmtp.h>
+#include <osmocom/sdp/sdp_strings.h>
+
 #include <errno.h>
 #include <stdlib.h>
 #include <limits.h>
@@ -55,7 +58,7 @@ struct sdp_rtp_map {
 };
 struct sdp_fmtp_param {
 	int payload_type;
-	struct mgcp_codec_param param;
+	const char *fmtp;
 };
 
 
@@ -195,11 +198,7 @@ static int fmtp_from_sdp(void *ctx, struct sdp_fmtp_param *fmtp_param, char *sdp
 {
 	char *str;
 	char *str_ptr;
-	char *param_str;
 	unsigned int pt;
-	unsigned int count = 0;
-	char delimiter;
-	unsigned int amr_octet_aligned;
 
 	memset(fmtp_param, 0, sizeof(*fmtp_param));
 
@@ -218,40 +217,13 @@ static int fmtp_from_sdp(void *ctx, struct sdp_fmtp_param *fmtp_param, char *sdp
 		goto error;
 	fmtp_param->payload_type = pt;
 
-	/* Advance pointer to the beginning of the parameter section and
-	 * tokenize string */
+	/* Advance pointer to the beginning of the parameter section */
 	str_ptr = strstr(str_ptr, " ");
 	if (!str_ptr)
 		goto error;
 	str_ptr++;
 
-	param_str = strtok(str_ptr, " ");
-	if (!param_str)
-		goto exit;
-
-	while (1) {
-		/* Make sure that we don't get trapped in an endless loop */
-		if (count > 256)
-			goto error;
-
-		/* Chop off delimiters ';' at the end */
-		delimiter = str_ptr[strlen(str_ptr) - 1];
-		if (delimiter == ';' || delimiter == ',')
-			str_ptr[strlen(str_ptr) - 1] = '\0';
-
-		/* AMR octet aligned parameter (see also RFC 3267, section 8.3) */
-		if (sscanf(param_str, "octet-align=%d", &amr_octet_aligned) == 1) {
-			fmtp_param->param.amr_octet_aligned_present = true;
-			fmtp_param->param.amr_octet_aligned = false;
-			if (amr_octet_aligned == 1)
-				fmtp_param->param.amr_octet_aligned = true;
-		}
-
-		param_str = strtok(NULL, " ");
-		if (!param_str)
-			break;
-		count++;
-	}
+	fmtp_param->fmtp = talloc_strdup(ctx, str_ptr);
 
 exit:
 	talloc_free(str);
@@ -299,13 +271,13 @@ static int audio_ip_from_sdp(struct osmo_sockaddr *dst_addr, char *sdp)
 
 /* Pick optional fmtp parameters by payload type, if there are no fmtp
  * parameters, a nullpointer is returned */
-static struct mgcp_codec_param *param_by_pt(int pt, struct sdp_fmtp_param *fmtp_params, unsigned int fmtp_params_len)
+static const char *param_by_pt(int pt, struct sdp_fmtp_param *fmtp_params, unsigned int fmtp_params_len)
 {
 	unsigned int i;
 
 	for (i = 0; i < fmtp_params_len; i++) {
 		if (fmtp_params[i].payload_type == pt)
-			return &fmtp_params[i].param;
+			return fmtp_params[i].fmtp;
 	}
 
 	return NULL;
@@ -326,7 +298,6 @@ int mgcp_parse_sdp_data(const struct mgcp_endpoint *endp,
 	unsigned int codecs_used = 0;
 	struct sdp_fmtp_param fmtp_params[MGCP_MAX_CODECS];
 	unsigned int fmtp_used = 0;
-	struct mgcp_codec_param *codec_param;
 	char ipbuf[INET6_ADDRSTRLEN];
 	char *line;
 	unsigned int i;
@@ -421,8 +392,8 @@ int mgcp_parse_sdp_data(const struct mgcp_endpoint *endp,
 
 	/* Store parsed codec information */
 	for (i = 0; i < codecs_used; i++) {
-		codec_param = param_by_pt(codecs[i].payload_type, fmtp_params, fmtp_used);
-		rc = mgcp_codec_add(conn, codecs[i].payload_type, codecs[i].map_line, codec_param);
+		const char *fmtp = param_by_pt(codecs[i].payload_type, fmtp_params, fmtp_used);
+		rc = mgcp_codec_add2(conn, codecs[i].payload_type, codecs[i].map_line, fmtp);
 		if (rc < 0)
 			LOGPENDP(endp, DLMGCP, LOGL_NOTICE, "failed to add codec\n");
 	}
@@ -436,10 +407,12 @@ int mgcp_parse_sdp_data(const struct mgcp_endpoint *endp,
 	if (codecs_used == 0)
 		LOGPC(DLMGCP, LOGL_NOTICE, "none");
 	for (i = 0; i < codecs_used; i++) {
-		LOGPC(DLMGCP, LOGL_NOTICE, "%d=%s",
+		LOGPC(DLMGCP, LOGL_NOTICE, " %d=%s%s%s%s",
 		      rtp->codecs[i].payload_type,
-		      strlen(rtp->codecs[i].subtype_name) ? rtp->codecs[i].subtype_name : "unknown");
-		LOGPC(DLMGCP, LOGL_NOTICE, " ");
+		      strlen(rtp->codecs[i].subtype_name) ? rtp->codecs[i].subtype_name : "unknown",
+		      rtp->codecs[i].fmtp[0] ? ",fmtp='" : "",
+		      rtp->codecs[i].fmtp,
+		      rtp->codecs[i].fmtp[0] ? "'" : "");
 	}
 	LOGPC(DLMGCP, LOGL_NOTICE, "\n");
 
@@ -494,18 +467,15 @@ static int add_fmtp(struct msgb *sdp, struct sdp_fmtp_param *fmtp_params, unsign
 	int rc;
 
 	for (i = 0; i < fmtp_params_len; i++) {
+		bool first = true;
 		rc = msgb_printf(sdp, "a=fmtp:%u", fmtp_params[i].payload_type);
 		if (rc < 0)
 			return -EINVAL;
 
 		/* Add amr octet align parameter */
-		if (fmtp_params[i].param.amr_octet_aligned_present) {
-			if (fmtp_params[i].param.amr_octet_aligned)
-				rc = msgb_printf(sdp, " octet-align=1");
-			else
-				rc = msgb_printf(sdp, " octet-align=0");
-			if (rc < 0)
-				return -EINVAL;
+		if (fmtp_params[i].fmtp) {
+			msgb_printf(sdp, "%s%s", first ? " " : ";", fmtp_params[i].fmtp);
+			first = false;
 		}
 
 		rc = msgb_printf(sdp, "\r\n");
@@ -529,7 +499,6 @@ int mgcp_write_response_sdp(const struct mgcp_endpoint *endp,
 	const struct mgcp_rtp_codec *codec;
 	const char *audio_name;
 	int payload_type;
-	struct sdp_fmtp_param fmtp_param;
 	int rc;
 	int payload_types[1];
 	int local_port;
@@ -578,12 +547,22 @@ int mgcp_write_response_sdp(const struct mgcp_endpoint *endp,
 				goto buffer_too_small;
 		}
 
-		if (codec->param_present) {
-			fmtp_param.payload_type = payload_type;
-			fmtp_param.param = codec->param;
-			fmtp_params[0] = fmtp_param;
+		if (codec->fmtp[0]) {
+			fmtp_params[0] = (struct sdp_fmtp_param){
+				.payload_type = payload_type,
+				.fmtp = codec->fmtp,
+			};
 			fmtp_params_len = 1;
+		} else if (codec->param_present) {
+			/* Legacy */
+			fmtp_params[0] = (struct sdp_fmtp_param){
+				.payload_type = payload_type,
+			};
+			fmtp_params_len = 1;
+			fmtp_params[0].fmtp = (codec->param.amr_octet_aligned ?
+					       OSMO_SDP_STR_AMR_OCTET_ALIGN_1 : OSMO_SDP_STR_AMR_OCTET_ALIGN_0);
 		}
+
 		rc = add_fmtp(sdp, fmtp_params, fmtp_params_len);
 		if (rc < 0)
 			goto buffer_too_small;

src/libosmo-sdp/Makefile.am

@@ -0,0 +1,28 @@
+AM_CPPFLAGS = \
+	$(all_includes) \
+	-I$(top_srcdir)/include \
+	-I$(top_builddir) \
+	$(NULL)
+
+AM_CFLAGS = \
+	-Wall \
+	$(LIBOSMOCORE_CFLAGS) \
+	$(TALLOC_CFLAGS) \
+	$(NULL)
+
+noinst_LTLIBRARIES = \
+	libosmo-sdp.la \
+	$(NULL)
+
+libosmo_sdp_la_SOURCES = \
+	sdp_codec.c \
+	sdp_codec_list.c \
+	sdp_msg.c \
+	sdp_internal.c \
+	fmtp.c \
+	$(NULL)
+
+libosmo_sdp_la_LIBADD = \
+	$(LIBOSMOCORE_LIBS) \
+	$(TALLOC_LIBS) \
+	$(NULL)

src/libosmo-sdp/fmtp.c

@@ -0,0 +1,193 @@
+/*
+ * (C) 2023-2024 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved
+ *
+ * Author: Neels Hofmeyr
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU Affero General Public License as published by
+ * the Free Software Foundation; either version 3 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU Affero General Public License for more details.
+ *
+ * You should have received a copy of the GNU Affero General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+#include <string.h>
+#include <ctype.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/logging.h>
+
+#include <osmocom/sdp/sdp_strings.h>
+#include <osmocom/sdp/fmtp.h>
+
+/* End of current fmtp parameter. Return a pointer to the next ';' character, if present, or the terminating '\0'. */
+static const char *osmo_sdp_fmtp_end(const char *fmtp)
+{
+	if (!fmtp)
+		return NULL;
+	for (; *fmtp && *fmtp != ';'; fmtp++);
+	return fmtp;
+}
+
+/* Start of next fmtp parameter. Return a pointer to the first character of the next fmtp parameter's name, or the
+ * terminating '\0'. */
+static const char *osmo_sdp_fmtp_next(const char *fmtp)
+{
+	if (!fmtp)
+		return NULL;
+	fmtp = osmo_sdp_fmtp_end(fmtp);
+	for (; *fmtp && (*fmtp == ';' || isspace(*fmtp)); fmtp++);
+	return fmtp;
+}
+
+/*! Parse a given SDP fmtp value string, returning the value of a specific option, if present.
+ *
+ * Example:
+ *
+ *   const char *fmtp_vals = "octet-align=1;mode-set=0,2,4,7";
+ *
+ *   char mode_set_str[23];
+ *   if (osmo_sdp_fmtp_get_val(mode_set_str, sizeof(mode_set_str), fmtp_vals, "mode-set")) {
+ *           // option 'mode-set' is present, now mode_set_str == "0,2,4,7"
+ *           use_modeset(mode_set_str);
+ *   } else {
+ *           // if 'mode-set' were not present...
+ *           use_modeset(MY_DEFAULT_MODESET);
+ *   }
+ *
+ * \param[out] val  Buffer to write the option's value to.
+ * \param[in] val_size  Space available in val.
+ * \param[in] fmtp  fmtp value string to parse -- must not contain the "a=fmtp:N " prefix, only the value part.
+ * \param[in] option_name  Which fmtp option to get the value for.
+ * \return true when the option was found, false when it was not present.
+ */
+bool osmo_sdp_fmtp_get_val(char *val, size_t val_size, const char *fmtp, const char *option_name)
+{
+	const char *pos = fmtp;
+	const char *end;
+	int option_name_len = strlen(option_name);
+	for (; pos && *pos; pos = osmo_sdp_fmtp_next(pos)) {
+		if (!osmo_str_startswith(pos, option_name))
+			continue;
+		pos += option_name_len;
+		if (*pos != '=')
+			continue;
+		pos++;
+		break;
+	}
+
+	if (!pos || !*pos)
+		return false;
+
+	end = osmo_sdp_fmtp_end(pos);
+	OSMO_ASSERT(end);
+	if (val && val_size)
+		osmo_strlcpy(val, pos, OSMO_MIN(val_size, end - pos + 1));
+	return true;
+}
+
+/*! Parse a given SDP fmtp value string, returning the value of a specific integer option, if present.
+ *
+ * Example:
+ *
+ *   const char *fmtp_vals = "octet-align=1;mode-set=0,2,4,7";
+ *   bool oa = osmo_sdp_fmtp_get_int(fmtp_vals, OSMO_SDP_AMR_OCTET_ALIGN_NAME, 1);
+ *
+ * \param[in] fmtp  fmtp value string to parse -- must not contain the "a=fmtp:N " prefix, only the value part.
+ * \param[in] option_name  Which fmtp option to get the value for.
+ * \param[in] default_value  If option_name is not present or cannot be parsed as integer, return this instead.
+ * \return the integer value when the option was found and actually an integer, default_value otherwise.
+ */
+int64_t osmo_sdp_fmtp_get_int(const char *fmtp, const char *option_name, int64_t default_value)
+{
+	char val[128];
+	if (!osmo_sdp_fmtp_get_val(val, sizeof(val), fmtp, option_name))
+		return default_value;
+	if (!val[0])
+		return default_value;
+	int64_t i;
+	if (osmo_str_to_int64(&i, val, 10, INT64_MIN, INT64_MAX)) {
+		/* error parsing number */
+		return default_value;
+	}
+	return i;
+}
+
+/*! Return true if octet-align is present and set to 1 in the given AMR related fmtp value.
+ * Default to octet-align=0, i.e. bandwidth-efficient mode.
+ *
+ * See RFC4867 "RTP Payload Format for AMR and AMR-WB" sections "8.1. AMR Media Type Registration" and "8.2. AMR-WB
+ * Media Type Registration":
+ *
+ *    octet-align: Permissible values are 0 and 1.  If 1, octet-align
+ *                 operation SHALL be used.  If 0 or if not present,
+ *                 bandwidth-efficient operation is employed.
+ *
+ * https://tools.ietf.org/html/rfc4867
+ */
+bool osmo_sdp_fmtp_amr_is_octet_aligned(const char *fmtp)
+{
+	return osmo_sdp_fmtp_get_int(fmtp, OSMO_SDP_STR_AMR_OCTET_ALIGN, 0) == 1;
+}
+
+static void strip_whitespace(char *str)
+{
+	char *i = str;
+	char *o = str;
+	for (; *i; i++, o++) {
+		while (isspace(*i))
+			i++;
+		*o = *i;
+		if (!*i)
+			break;
+	}
+}
+
+/* Return true when the two AMR type fmtp strings can be considered equivalent.
+ * - Omission of octet-align is equivalent to having octet-align=0 present (0 is the default).
+ * - Omission of 'mode-set' means, match any and all codec modes. So if either a or b have no 'mode-set', it's a match.
+ *   If both have 'mode-set' present, they must be identical to match. Do not sort the mode-set string, but strip
+ *   whitespace.
+ * - TODO all other parameters are currently completely ignored.
+ */
+bool osmo_sdp_fmtp_amr_match(const char *a, const char *b)
+{
+	char a_modeset[32] = {};
+	char b_modeset[32] = {};
+	bool a_ok;
+	bool b_ok;
+
+	if (!a)
+		a = "";
+	if (!b)
+		b = "";
+
+	/* octet-align=1. Omission means octet-align=0 */
+	if (osmo_sdp_fmtp_amr_is_octet_aligned(a) != osmo_sdp_fmtp_amr_is_octet_aligned(b))
+		return false;
+
+	/* mode-set=0,1,2,3,4,5,6,7 */
+	a_ok = osmo_sdp_fmtp_get_val(a_modeset, sizeof(a_modeset), a, "mode-set");
+	b_ok = osmo_sdp_fmtp_get_val(b_modeset, sizeof(b_modeset), b, "mode-set");
+	if (a_ok && b_ok) {
+		/* Strip whitespace: We don't know what remote SDP peers may throw at us. There could be whitespace
+		 * around the separators like 'mode-set=2,3 ; octet-align=1', which may show up here as whitespace in
+		 * the value string as "2,3 ", which would mismatch "2,3". */
+		strip_whitespace(a_modeset);
+		strip_whitespace(b_modeset);
+		if (strcmp(a_modeset, b_modeset))
+			return false;
+	}
+
+	/* TODO: treat other AMR traits, see RFC4867 8.1. Maybe generically match all values that are present?
+	 * So far we have no need for other values than octet-align and mode-set. */
+
+	/* No mismatch found, it's a match */
+	return true;
+}

src/libosmo-sdp/sdp_codec.c

@@ -0,0 +1,251 @@
+/* Codec management in SDP messages. */
+/*
+ * (C) 2024 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ *
+ * Author: Neels Janosch Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <ctype.h>
+
+#include <osmocom/core/utils.h>
+
+#include <osmocom/sdp/fmtp.h>
+#include <osmocom/sdp/sdp_codec.h>
+#include <osmocom/sdp/sdp_internal.h>
+
+struct osmo_sdp_codec *osmo_sdp_codec_alloc(void *ctx)
+{
+	return talloc_zero(ctx, struct osmo_sdp_codec);
+}
+
+int osmo_sdp_codec_set(struct osmo_sdp_codec *c,
+		       int8_t payload_type, const char *encoding_name, unsigned int rate, const char *fmtp)
+{
+	c->rate = rate;
+	osmo_sdp_codec_set_encoding_name(c, encoding_name);
+	osmo_sdp_codec_set_fmtp(c, fmtp);
+	c->payload_type = payload_type;
+	return 0;
+}
+
+int osmo_sdp_codec_set_encoding_name(struct osmo_sdp_codec *c, const char *encoding_name)
+{
+	osmo_talloc_replace_string(c, &c->encoding_name, encoding_name);
+	return 0;
+}
+
+int osmo_sdp_codec_set_fmtp(struct osmo_sdp_codec *c, const char *fmtp)
+{
+	osmo_talloc_replace_string(c, &c->fmtp, fmtp);
+	return 0;
+}
+
+bool osmo_sdp_codec_is_set(const struct osmo_sdp_codec *a)
+{
+	return a && a->encoding_name && a->encoding_name[0];
+}
+
+int osmo_sdp_codec_to_str_buf(char *buf, size_t buflen, const struct osmo_sdp_codec *codec)
+{
+	struct osmo_strbuf sb = { .buf = buf, .len = buflen };
+	if (!codec) {
+		OSMO_STRBUF_PRINTF(sb, "NULL");
+		return sb.chars_needed;
+	}
+	if (codec->encoding_name && codec->encoding_name[0])
+		OSMO_STRBUF_PRINTF(sb, "%s", codec->encoding_name);
+	if (codec->rate != 8000)
+		OSMO_STRBUF_PRINTF(sb, "/%u", codec->rate);
+	if (codec->fmtp && codec->fmtp[0])
+		OSMO_STRBUF_PRINTF(sb, ":%s", codec->fmtp);
+	OSMO_STRBUF_PRINTF(sb, "#%d", codec->payload_type);
+	return sb.chars_needed;
+}
+
+char *osmo_sdp_codec_to_str_c(void *ctx, const struct osmo_sdp_codec *codec)
+{
+	OSMO_NAME_C_IMPL(ctx, 32, "osmo_sdp_codec_to_str_c-ERROR", osmo_sdp_codec_to_str_buf, codec)
+}
+
+/*! Parse a codec string as from osmo_sdp_codec_to_str_buf() back to an osmo_sdp_codec struct.
+ * Write the parsed result to *dst, using ctx as talloc parent.
+ * The input string is like <encoding_name>[:<fmtp-string>][#<payload-type-nr>]
+ * for example:
+ *    "FOO:my-fmtp=1;my-other-fmtp=2#42"
+ * Note that ';' are separators only within the fmtp string. This function does not separate those. In above example,
+ * the fmtp string part is "my-fmtp=val;my-other-fmtp=val2" and ends up in dst->ftmp as-is.
+ * Parse at most str_len characters, or the entire string when str_len < 0 or str_len > strlen(str).
+ * Return 0 on success, negative on failure. */
+int osmo_sdp_codec_from_str(struct osmo_sdp_codec *dst, const char *str, int str_len)
+{
+	const char *pos = str;
+	const char *str_end = str + (str_len >= 0 ? str_len : strlen(str));
+	const char *p2;
+
+	struct token token_encoding_name = {};
+	struct token token_rate = {};
+	struct token token_fmtp = {};
+	struct token token_payload_type = {};
+
+	struct token *new_t = NULL;
+	/* start with the encoding name */
+	struct token *t = &token_encoding_name;
+	t->start = pos;
+
+	for (; pos < str_end; pos++) {
+		new_t = NULL;
+		switch (*pos) {
+		case '/':
+			new_t = &token_rate;
+			break;
+		case ':':
+			new_t = &token_fmtp;
+			break;
+		case '#':
+			/* count this '#' only if there is no other one following. It might be part of a fmtp. */
+			for (p2 = pos + 1; p2 < str_end; p2++)
+				if (*p2 == '#')
+					break;
+			if (p2 < str_end && *p2 == '#')
+				break;
+			/* This is the last '#' in the string. Count it only when a digit follows. */
+			if (!isdigit(pos[1]))
+				break;
+			new_t = &token_payload_type;
+			break;
+		default:
+			break;
+		}
+		if (!new_t)
+			continue;
+		/* If we already have a token for a start character, don't start it again. These may be part of a fmtp
+		 * string. */
+		if (new_t == t)
+			continue;
+		t->end = pos;
+		t = new_t;
+		t->start = pos + 1;
+	}
+	t->end = pos;
+
+	token_copy(dst, &dst->encoding_name, &token_encoding_name);
+	if (token_rate.start)
+		dst->rate = atoi(token_rate.start);
+	else
+		dst->rate = 8000;
+	token_copy(dst, &dst->fmtp, &token_fmtp);
+	if (token_payload_type.start)
+		dst->payload_type = atoi(token_payload_type.start);
+	return 0;
+}
+
+/* Compare both payload type number and fmtp string 1:1 */
+const struct osmo_sdp_codec_cmp_flags osmo_sdp_codec_cmp_exact = {
+	.payload_type = true,
+	.encoding_name = true,
+	.rate = true,
+	.fmtp = OSMO_SDP_CMP_EXACT,
+};
+
+/* Ignore payload type number; compare fmtp string by meaning when possible, else 1:1 */
+const struct osmo_sdp_codec_cmp_flags osmo_sdp_codec_cmp_equivalent = {
+	.payload_type = false,
+	.encoding_name = true,
+	.rate = true,
+	.fmtp = OSMO_SDP_CMP_EQUIVALENT,
+};
+
+/* Compare only encoding name */
+const struct osmo_sdp_codec_cmp_flags osmo_sdp_codec_cmp_name = {
+	.payload_type = false,
+	.encoding_name = true,
+	.rate = false,
+	.fmtp = OSMO_SDP_CMP_IGNORE,
+};
+
+extern const struct osmo_sdp_codec_cmp_flags osmo_sdp_codec_cmp_equivalent;
+static inline int strcmp_safe(const char *a, const char *b)
+{
+	return strcmp(a ? : "", b ? : "");
+}
+
+/*! Compare encoding name, rate and fmtp, returning cmp result: -1 if a < b, 0 if a == b, 1 if a > b.
+ * Compare as defined in 'cmp':
+ * If cmpf->payload_type is false, ignore payload_type numbers.
+ * If cmpf->rate is false, ignore rate.
+ * If cmpf->fmtp is OSMO_SDP_CMP_IGNORE, ignore fmtp strings.
+ * If cmpf->fmtp is OSMO_SDP_CMP_EXACT, use strcmp() to match fmtp 1:1.
+ * If cmpf->fmtp is OSMO_SDP_CMP_EQUIVALENT, use specific fmtp knowledge to match equivalent entries;
+ *  - AMR fmtp matching is done by osmo_sdp_fmtp_amr_match().
+ *  - for all others, still compare fmtp 1:1.
+ */
+int osmo_sdp_codec_cmp(const struct osmo_sdp_codec *a, const struct osmo_sdp_codec *b,
+		       const struct osmo_sdp_codec_cmp_flags *cmpf)
+{
+	int cmp;
+	if (a == b)
+		return 0;
+	if (!a)
+		return -1;
+	if (!b)
+		return 1;
+
+	if (!cmpf)
+		cmpf = &osmo_sdp_codec_cmp_exact;
+
+	if (cmpf->encoding_name) {
+		cmp = strcmp_safe(a->encoding_name, b->encoding_name);
+		if (cmp)
+			return cmp;
+	}
+
+	if (cmpf->rate) {
+		cmp = OSMO_CMP(a->rate, b->rate);
+		if (cmp)
+			return cmp;
+	}
+
+	switch (cmpf->fmtp) {
+	default:
+	case OSMO_SDP_CMP_EXACT:
+		cmp = strcmp_safe(a->fmtp, b->fmtp);
+		break;
+
+	case OSMO_SDP_CMP_EQUIVALENT:
+		/* In case of AMR, allow logical matching; we only need to do that if the strings differ. */
+		cmp = strcmp_safe(a->fmtp, b->fmtp);
+		if (cmp
+		    && !strcmp_safe("AMR", a->encoding_name)
+		    && osmo_sdp_fmtp_amr_match(a->fmtp, b->fmtp))
+			cmp = 0;
+		break;
+
+	case OSMO_SDP_CMP_IGNORE:
+		cmp = 0;
+		break;
+	}
+	if (cmp)
+		return cmp;
+
+	if (cmpf->payload_type)
+		cmp = OSMO_CMP(a->payload_type, b->payload_type);
+
+	return cmp;
+}

src/libosmo-sdp/sdp_codec_list.c

@@ -0,0 +1,367 @@
+/* Codec management in SDP messages. */
+/*
+ * (C) 2024 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ *
+ * Author: Neels Janosch Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <string.h>
+
+#include <osmocom/core/utils.h>
+
+#include <osmocom/sdp/sdp_codec_list.h>
+
+struct osmo_sdp_codec_list *osmo_sdp_codec_list_alloc(void *ctx)
+{
+	struct osmo_sdp_codec_list *codec_list = talloc_zero(ctx, struct osmo_sdp_codec_list);
+	INIT_LLIST_HEAD(&codec_list->list);
+	return codec_list;
+}
+
+/*! Free all items contained in this list, do not free the list itself (leave an empty list). */
+void osmo_sdp_codec_list_free_items(struct osmo_sdp_codec_list *codec_list)
+{
+	struct osmo_sdp_codec *c;
+	while ((c = osmo_sdp_codec_list_first(codec_list))) {
+		osmo_sdp_codec_list_remove_entry(c);
+		talloc_free(c);
+	}
+}
+
+struct osmo_sdp_codec *osmo_sdp_codec_list_add_empty(struct osmo_sdp_codec_list *codec_list)
+{
+	struct osmo_sdp_codec *c = osmo_sdp_codec_alloc(codec_list);
+	llist_add_tail(&c->entry, &codec_list->list);
+	return c;
+}
+
+int8_t osmo_sdp_codec_list_get_unused_dyn_pt_nr(const struct osmo_sdp_codec_list *codec_list, int8_t suggest_pt_nr)
+{
+	bool present[127 - 96 + 1] = {};
+	const struct osmo_sdp_codec *c;
+	bool suggest_pt_nr_exists = false;
+	int i;
+
+	osmo_sdp_codec_list_foreach (c, codec_list) {
+		if (c->payload_type >= 96 && c->payload_type <= 127)
+			present[c->payload_type - 96] = true;
+		if (c->payload_type == suggest_pt_nr)
+			suggest_pt_nr_exists = true;
+	}
+
+	if (!suggest_pt_nr_exists)
+		return suggest_pt_nr;
+
+	/* The desired number is already taken, see which of the dynamic types is not taken yet */
+	for (i = 96; i <= 127; i++) {
+		/* For dynamic allocations, skip these predefined numbers, taken from enum mgcp_codecs:
+		 * CODEC_GSMEFR_8000_1 = 110,	3GPP TS 48.103 table 5.4.2.2.1
+		 * CODEC_GSMHR_8000_1 = 111,	3GPP TS 48.103 table 5.4.2.2.1
+		 * CODEC_AMR_8000_1 = 112,		3GPP TS 48.103 table 5.4.2.2.1
+		 * CODEC_AMRWB_16000_1 = 113,	3GPP TS 48.103 table 5.4.2.2.1
+		 * CODEC_CLEARMODE = 120,		3GPP TS 48.103 table 5.4.2.2.1
+		 */
+		if (i >= 110 && i <= 113)
+			continue;
+		else if (i == 120)
+			continue;
+
+		if (!present[i - 96])
+			return i;
+	}
+
+	return -1;
+}
+
+/*! Allocate a new entry in codec_list and copy codec's values to it.
+ * If once is NULL, unconditionally add a new codec entry.
+ * If once is non-NULL, do not add a new entry when the list already contains a matching entry; for determining a match,
+ * use the once->flags. For example, if once = &osmo_sdp_codec_cmp_equivalent, look up if codec_list has a similar
+ * codec, and add the new entry only if it is not listed.
+ * See osmo_sdp_codec_cmp() and osmo_sdp_fmtp_amr_match() for details.
+ * Return the new entry, or the equivalent entry already present in the list.
+ */
+struct osmo_sdp_codec *osmo_sdp_codec_list_add(struct osmo_sdp_codec_list *codec_list,
+					       const struct osmo_sdp_codec *codec,
+					       const struct osmo_sdp_codec_cmp_flags *once, bool pick_unused_pt_nr)
+{
+	struct osmo_sdp_codec *new_entry;
+	int8_t payload_type;
+
+	if (once) {
+		struct osmo_sdp_codec *c;
+		osmo_sdp_codec_list_foreach (c, codec_list)
+			if (!osmo_sdp_codec_cmp(codec, c, once))
+				return c;
+	}
+
+	/* Adjust payload_type number? */
+	payload_type = codec->payload_type;
+	if (pick_unused_pt_nr)
+		payload_type = osmo_sdp_codec_list_get_unused_dyn_pt_nr(codec_list, payload_type);
+
+	/* Take provided values, possibly modified payload_type */
+	new_entry = osmo_sdp_codec_list_add_empty(codec_list);
+	osmo_sdp_codec_set(new_entry, payload_type, codec->encoding_name, codec->rate, codec->fmtp);
+
+	return new_entry;
+}
+
+/*! Remove and free all entries from the codec_list that match the given codec according to osmo_sdp_codec_cmp(cmpf).
+ * Return the number of entries freed. */
+int osmo_sdp_codec_list_remove(struct osmo_sdp_codec_list *codec_list, const struct osmo_sdp_codec *codec,
+			       const struct osmo_sdp_codec_cmp_flags *cmpf)
+{
+	struct osmo_sdp_codec *i, *j;
+	int count = 0;
+	osmo_sdp_codec_list_foreach_safe (i, j, codec_list) {
+		if (osmo_sdp_codec_cmp(i, codec, cmpf))
+			continue;
+		osmo_sdp_codec_list_remove_entry(i);
+		talloc_free(i);
+		count++;
+	}
+	return count;
+}
+
+/*! Unlink an osmo_sdp_codec from an osmo_sdp_codec_list, if the codec instance is part of a list. Do not free the
+ * struct osmo_sdp_codec.
+ */
+void osmo_sdp_codec_list_remove_entry(struct osmo_sdp_codec *codec)
+{
+	/* The codec is not part of a list in these cases:
+	 * After talloc_zero(), next == NULL.
+	 * After llist_del(), next == LLIST_POISON1. */
+	if (codec->entry.next != NULL
+	    && codec->entry.next != (struct llist_head *)LLIST_POISON1)
+		llist_del(&codec->entry);
+}
+
+static inline int strcmp_safe(const char *a, const char *b)
+{
+	return strcmp(a ? : "", b ? : "");
+}
+
+/*! Short single-line representation of a list of SDP audio codecs, convenient for logging.
+ * If summarize == true, collapse variants of the same encoding_name (in practice, don't show all of the various AMR
+ * fmtp permutations). If summarize == false, print each and every codec in full.
+ */
+int osmo_sdp_codec_list_to_str_buf(char *buf, size_t buflen, const struct osmo_sdp_codec_list *codec_list, bool summarize)
+{
+	struct osmo_strbuf sb = { .buf = buf, .len = buflen };
+	const struct osmo_sdp_codec *codec;
+	bool first;
+
+	if (llist_empty(&codec_list->list)) {
+		OSMO_STRBUF_PRINTF(sb, "(no-codecs)");
+		return sb.chars_needed;
+	}
+
+	if (!summarize) {
+		first = true;
+		osmo_sdp_codec_list_foreach (codec, codec_list) {
+			if (!first)
+				OSMO_STRBUF_PRINTF(sb, " ");
+			OSMO_STRBUF_APPEND(sb, osmo_sdp_codec_to_str_buf, codec);
+			first = false;
+		}
+		return sb.chars_needed;
+	}
+
+	/* summarize */
+	first = true;
+	osmo_sdp_codec_list_foreach (codec, codec_list) {
+		const struct osmo_sdp_codec *c2;
+		int count = 0;
+		bool various_pt = false;
+
+		/* When this encoding name has been handled before, skip it now. */
+		osmo_sdp_codec_list_foreach (c2, codec_list) {
+			if (c2 == codec)
+				break;
+			if (!strcmp_safe(codec->encoding_name, c2->encoding_name)) {
+				count = 1;
+				break;
+			}
+		}
+		if (count)
+			continue;
+
+		/* Not seen this encoding_name before, count total occurences */
+		count = 0;
+		osmo_sdp_codec_list_foreach (c2, codec_list) {
+			if (!strcmp_safe(codec->encoding_name, c2->encoding_name)) {
+				count++;
+				if (codec->payload_type != c2->payload_type)
+					various_pt = true;
+			}
+		}
+
+		if (!first)
+			OSMO_STRBUF_PRINTF(sb, " ");
+		if (count > 1)
+			OSMO_STRBUF_PRINTF(sb, "%d*", count);
+		OSMO_STRBUF_PRINTF(sb, "%s", codec->encoding_name);
+		if (!various_pt)
+			OSMO_STRBUF_PRINTF(sb, "#%d", codec->payload_type);
+		first = false;
+	}
+	return sb.chars_needed;
+}
+
+char *osmo_sdp_codec_list_to_str_c(void *ctx, const struct osmo_sdp_codec_list *codec_list, bool summarize)
+{
+	OSMO_NAME_C_IMPL(ctx, 128, "osmo_sdp_codec_list_to_str_c-ERROR", osmo_sdp_codec_list_to_str_buf, codec_list, summarize)
+}
+
+/*! Return first entry, or NULL if the list is empty. */
+struct osmo_sdp_codec *osmo_sdp_codec_list_first(const struct osmo_sdp_codec_list *list)
+{
+	return llist_first_entry_or_null(&list->list, struct osmo_sdp_codec, entry);
+}
+
+/*! Move entries matching 'codec' to the front of the list. Matching is done via osmo_sdp_codec_cmp(cmpf).
+ * Return the number of matches that are now at the front of the list.
+ */
+int osmo_sdp_codec_list_move_to_first(struct osmo_sdp_codec_list *codec_list, const struct osmo_sdp_codec *codec,
+				      const struct osmo_sdp_codec_cmp_flags *cmpf)
+{
+	struct llist_head *head = &codec_list->list;
+	struct osmo_sdp_codec *i, *j;
+	int matches_found = 0;
+	osmo_sdp_codec_list_foreach_safe (i, j, codec_list) {
+		if (osmo_sdp_codec_cmp(codec, i, cmpf))
+			continue;
+		/* It's a match, move to the head */
+		osmo_sdp_codec_list_remove_entry(i);
+		llist_add(&i->entry, head);
+		matches_found++;
+		/* If more matches show up later, add them *after* the one just moved to the front. */
+		head = &i->entry;
+	}
+
+	return matches_found;
+}
+
+/*! Compare two lists of SDP codecs, returning cmp result: -1 if a < b, 0 if a == b, 1 if a > b.
+ * The two lists are compared in order, item by item, using osmo_sdp_codec_cmp(cmpf).
+ */
+int osmo_sdp_codec_list_cmp(const struct osmo_sdp_codec_list *a, const struct osmo_sdp_codec_list *b,
+			    const struct osmo_sdp_codec_cmp_flags *cmpf)
+{
+	const struct llist_head *a_start;
+	const struct llist_head *a_pos;
+	const struct llist_head *b_start;
+	const struct llist_head *b_pos;
+	int cmp;
+
+	/* NULL pointer == empty list */
+	if (a && llist_empty(&a->list))
+		a = NULL;
+	if (b && llist_empty(&a->list))
+		b = NULL;
+
+	/* are one or both empty? */
+	if (a == b)
+		return 0;
+	if (!a)
+		return -1;
+	if (!b)
+		return 1;
+
+	/* compare item by item */
+	a_start = &a->list;
+	a_pos = a_start->next;
+	b_start = &b->list;
+	b_pos = b_start->next;
+
+	for (; a_pos != a_start; a_pos = a_pos->next, b_pos = b_pos->next) {
+		const struct osmo_sdp_codec *codec_a;
+		const struct osmo_sdp_codec *codec_b;
+
+		if (b_pos == b_start) {
+			/* there is an entry in a, but b has already ended. mismatch. */
+			return 1;
+		}
+
+		codec_a = llist_entry(a_pos, struct osmo_sdp_codec, entry);
+		codec_b = llist_entry(b_pos, struct osmo_sdp_codec, entry);
+		cmp = osmo_sdp_codec_cmp(codec_a, codec_b, cmpf);
+		if (cmp)
+			return cmp;
+	}
+
+	if (b_pos != b_start) {
+		/* 'a' has ended, but 'b' has more items. mismatch. */
+		return -1;
+	}
+
+	/* full match. */
+	return 0;
+}
+
+/*! Leave only those codecs in 'dst' that are also present in 'other'.
+ * The matching is made by osmo_sdp_codec_cmp(cmpf).
+ * If translate_payload_type_numbers has an effect if 'dst' and 'other' have mismatching payload_type numbers for the
+ * same SDP codec descriptions. If translate_payload_type_numbers is true, take the payload_type numbers from 'other'.
+ * If false, keep payload_type numbers in 'dst' unchanged. */
+void osmo_sdp_codec_list_intersection(struct osmo_sdp_codec_list *dst, const struct osmo_sdp_codec_list *other,
+				      const struct osmo_sdp_codec_cmp_flags *cmpf,
+				      bool translate_payload_type_numbers)
+{
+	struct osmo_sdp_codec *i, *j;
+	osmo_sdp_codec_list_foreach_safe (i, j, dst) {
+		struct osmo_sdp_codec *o;
+		struct osmo_sdp_codec *match = NULL;
+		osmo_sdp_codec_list_foreach (o, other) {
+			if (osmo_sdp_codec_cmp(i, o, cmpf))
+				continue;
+			match = o;
+			break;
+		}
+
+		if (!match) {
+			osmo_sdp_codec_list_remove_entry(i);
+			talloc_free(i);
+			continue;
+		}
+
+		if (translate_payload_type_numbers)
+			i->payload_type = match->payload_type;
+	}
+}
+
+/* Find an entry for the given payload_type number in the given list of codecs. */
+struct osmo_sdp_codec *osmo_sdp_codec_list_by_payload_type(struct osmo_sdp_codec_list *codec_list, int8_t payload_type)
+{
+	struct osmo_sdp_codec *codec;
+	osmo_sdp_codec_list_foreach(codec, codec_list) {
+		if (codec->payload_type == payload_type)
+			return codec;
+	}
+	return NULL;
+}
+
+bool osmo_sdp_codec_list_is_empty(const struct osmo_sdp_codec_list *codec_list)
+{
+	if (!codec_list)
+		return true;
+	return llist_empty(&codec_list->list);
+}

src/libosmo-sdp/sdp_internal.c

@@ -0,0 +1,47 @@
+/*
+ * (C) 2024 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ *
+ * Author: Neels Janosch Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <stddef.h>
+
+#include <osmocom/core/talloc.h>
+#include <osmocom/core/utils.h>
+
+#include <osmocom/sdp/sdp_internal.h>
+
+/* Copy a string from t->start to t->end, return as talloc allocated under ctx in *dst.
+ * If *dst is non-NULL, talloc_free(*dst) first. */
+void token_copy(void *ctx, char **dst, const struct token *t)
+{
+	size_t len;
+	if (*dst)
+		talloc_free(*dst);
+	if (!t->start || !(t->end > t->start)) {
+		*dst = NULL;
+		return;
+	}
+
+	len = t->end - t->start;
+	*dst = talloc_size(ctx, len + 1);
+	osmo_strlcpy(*dst, t->start, len + 1);
+	talloc_set_name_const(*dst, *dst);
+}

src/libosmo-sdp/sdp_msg.c

@@ -0,0 +1,471 @@
+/* Implementation for SDP message encoding and decoding */
+/*
+ * (C) 2024 by sysmocom - s.f.m.c. GmbH <info@sysmocom.de>
+ * All Rights Reserved.
+ *
+ * Author: Neels Janosch Hofmeyr <nhofmeyr@sysmocom.de>
+ *
+ * SPDX-License-Identifier: GPL-2.0+
+ *
+ *  This program is free software; you can redistribute it and/or modify
+ *  it under the terms of the GNU General Public License as published by
+ *  the Free Software Foundation; either version 2 of the License, or
+ *  (at your option) any later version.
+ *
+ *  This program is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ *  GNU General Public License for more details.
+ *
+ *  You should have received a copy of the GNU General Public License
+ *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+#include <inttypes.h>
+#include <errno.h>
+#include <ctype.h>
+
+#include <osmocom/core/utils.h>
+
+#include <osmocom/sdp/sdp_msg.h>
+#include <osmocom/sdp/sdp_strings.h>
+#include <osmocom/sdp/sdp_internal.h>
+
+static const char * const mdir_str[] = {
+	[OSMO_SDP_MDIR_UNSET] = "-",
+	[OSMO_SDP_MDIR_SENDONLY] = OSMO_SDP_STR_SENDONLY,
+	[OSMO_SDP_MDIR_RECVONLY] = OSMO_SDP_STR_RECVONLY,
+	[OSMO_SDP_MDIR_SENDRECV] = OSMO_SDP_STR_SENDRECV,
+	[OSMO_SDP_MDIR_INACTIVE] = OSMO_SDP_STR_INACTIVE,
+};
+
+/*! Convert struct osmo_sdp_msg to the actual SDP protocol representation. */
+int osmo_sdp_msg_encode_buf(char *dst, size_t dst_size, const struct osmo_sdp_msg *sdp)
+{
+	const struct osmo_sdp_codec *codec;
+	struct osmo_strbuf sb = { .buf = dst, .len = dst_size };
+	const char *oip;
+	char oipv;
+	const char *ip;
+	char ipv;
+
+	if (!sdp) {
+		OSMO_STRBUF_PRINTF(sb, "%s", "");
+		return sb.chars_needed;
+	}
+
+	oip = sdp->origin.addr.ip[0] ? sdp->origin.addr.ip : "0.0.0.0";
+	oipv = (osmo_ip_str_type(oip) == AF_INET6) ? '6' : '4';
+
+	ip = sdp->rtp.ip[0] ? sdp->rtp.ip : "0.0.0.0";
+	ipv = (osmo_ip_str_type(oip) == AF_INET6) ? '6' : '4';
+
+	OSMO_STRBUF_PRINTF(sb,
+			   "v=0\r\n"
+			   "o=%s %s %s IN IP%c %s\r\n"
+			   "s=%s\r\n"
+			   "c=IN IP%c %s\r\n"
+			   "t=%"PRId64" %"PRId64"\r\n"
+			   "m=audio %d RTP/AVP",
+			   sdp->origin.username ? : "libosmo-sdp",
+			   sdp->origin.sess_id ? : "0", sdp->origin.sess_version ? : "0",
+			   oipv, oip,
+			   sdp->session_name ? : "-",
+			   ipv, ip,
+			   sdp->time_active.start,
+			   sdp->time_active.stop,
+			   sdp->rtp.port);
+
+	/* Append all payload type numbers to 'm=audio <port> RTP/AVP 3 4 112' line */
+	osmo_sdp_codec_list_foreach(codec, sdp->codecs)
+		OSMO_STRBUF_PRINTF(sb, " %d", codec->payload_type);
+	OSMO_STRBUF_PRINTF(sb, "\r\n");
+
+	/* Add details for all codecs */
+	osmo_sdp_codec_list_foreach(codec, sdp->codecs) {
+		if (!osmo_sdp_codec_is_set(codec))
+			continue;
+		OSMO_STRBUF_PRINTF(sb, OSMO_SDP_A_PREFIX(OSMO_SDP_STR_RTPMAP) "%d %s/%d\r\n", codec->payload_type, codec->encoding_name,
+				   codec->rate > 0 ? codec->rate : 8000);
+		if (codec->fmtp && codec->fmtp[0])
+			OSMO_STRBUF_PRINTF(sb, OSMO_SDP_A_PREFIX(OSMO_SDP_STR_FMTP) "%d %s\r\n", codec->payload_type, codec->fmtp);
+	}
+
+	if (sdp->ptime)
+		OSMO_STRBUF_PRINTF(sb, OSMO_SDP_A_PREFIX(OSMO_SDP_STR_PTIME) "%d\r\n", sdp->ptime);
+
+	if (sdp->media_direction != OSMO_SDP_MDIR_UNSET && sdp->media_direction < ARRAY_SIZE(mdir_str))
+		OSMO_STRBUF_PRINTF(sb, "a=%s\r\n", mdir_str[sdp->media_direction]);
+
+	return sb.chars_needed;
+}
+
+char *osmo_sdp_msg_encode_c(void *ctx, const struct osmo_sdp_msg *sdp)
+{
+	OSMO_NAME_C_IMPL(ctx, 256, "osmo_sdp_msg_to_str_c-ERROR", osmo_sdp_msg_encode_buf, sdp)
+}
+
+/* Return the first line ending (or the end of the string) at or after the given string position. */
+const char *get_line_end(const char *src)
+{
+	const char *line_end = strchr(src, '\r');
+	if (!line_end)
+		line_end = strchr(src, '\n');
+	if (!line_end)
+		line_end = src + strlen(src);
+	return line_end;
+}
+
+static bool str_is_attrib(const char *str, const char *attrib_name, char expect_next_char)
+{
+	char next_c;
+	if (!osmo_str_startswith(str, attrib_name))
+		return false;
+	next_c = str[strlen(attrib_name)];
+	if (expect_next_char == next_c)
+		return true;
+	/* Treat \0 as equivalent with line end */
+	if (!expect_next_char && (next_c == '\r' || next_c == '\n'))
+		return true;
+	/* It started with the string, but continued otherwise */
+	return false;
+}
+
+static enum osmo_sdp_media_direcion_e check_for_media_direction(const char *str)
+{
+	int i;
+	for (i = 0; i < ARRAY_SIZE(mdir_str); i++) {
+		if (i == OSMO_SDP_MDIR_UNSET)
+			continue;
+		if (str_is_attrib(str, mdir_str[i], 0))
+			return i;
+	}
+	return OSMO_SDP_MDIR_UNSET;
+}
+
+static struct osmo_sdp_codec *find_or_create_payload_type(struct osmo_sdp_msg *sdp, unsigned int payload_type)
+{
+	struct osmo_sdp_codec *codec;
+	codec = osmo_sdp_codec_list_by_payload_type(sdp->codecs, payload_type);
+	if (!codec) {
+		codec = osmo_sdp_codec_list_add_empty(sdp->codecs);
+		codec->payload_type = payload_type;
+		codec->rate = 8000;
+	}
+	return codec;
+}
+
+
+/* parse a line like 'a=rtpmap:0 PCMU/8000', 'a=fmtp:112 octet-align=1; mode-set=4', 'a=ptime:20'.
+ * The src should point at the character after 'a=', e.g. at the start of 'rtpmap', 'fmtp', 'ptime'
+ */
+int sdp_parse_attrib(struct osmo_sdp_msg *sdp, const char *src)
+{
+	unsigned int payload_type;
+	struct osmo_sdp_codec *codec;
+	enum osmo_sdp_media_direcion_e mdir;
+	const char *line_end = get_line_end(src);
+
+	if (str_is_attrib(src, OSMO_SDP_STR_RTPMAP, ':')) {
+		/* "a=rtpmap:96 AMR/8000" */
+		struct token audio_name;
+		const char *slash;
+		if (sscanf(src, OSMO_SDP_STR_RTPMAP ":%u", &payload_type) != 1)
+			return -EINVAL;
+
+		codec = find_or_create_payload_type(sdp, payload_type);
+
+		audio_name.start = strchr(src, ' ');
+		if (!audio_name.start)
+			return -EINVAL;
+		audio_name.start++;
+		if (audio_name.start >= get_line_end(src))
+			return -EINVAL;
+
+		slash = strchr(audio_name.start, '/');
+
+		audio_name.end = slash ? : line_end;
+		token_copy(codec, &codec->encoding_name, &audio_name);
+
+		if (audio_name.end >= line_end) {
+			/* There should be a "/8000" here. If it is missing, let's not be strict about it. */
+			codec->rate = 8000;
+		} else {
+			unsigned int channels = 1;
+			if (sscanf(audio_name.end, "/%u/%u", &codec->rate, &channels) < 1)
+				return -EINVAL;
+
+			if (channels != 1)
+				return -ENOTSUP;
+		}
+	}
+
+	else if (str_is_attrib(src, OSMO_SDP_STR_FMTP, ':')) {
+		/* "a=fmtp:112 octet-align=1;mode-set=0,1,2,3" */
+		struct token fmtp_str;
+		const char *line_end = get_line_end(src);
+		if (sscanf(src, OSMO_SDP_STR_FMTP ":%u", &payload_type) != 1)
+			return -EINVAL;
+
+		codec = find_or_create_payload_type(sdp, payload_type);
+
+		fmtp_str.start = strchr(src, ' ');
+		if (!fmtp_str.start)
+			return -EINVAL;
+		fmtp_str.start++;
+		if (fmtp_str.start >= line_end)
+			return -EINVAL;
+
+		fmtp_str.end = line_end;
+		token_copy(codec, &codec->fmtp, &fmtp_str);
+	}
+
+	else if (str_is_attrib(src, OSMO_SDP_STR_PTIME, ':')) {
+		/* "a=ptime:20" */
+		if (sscanf(src, OSMO_SDP_STR_PTIME ":%u", &sdp->ptime) != 1)
+			return -EINVAL;
+
+	}
+
+	/* "a=sendrecv" ... */
+	else if ((mdir = check_for_media_direction(src)) != OSMO_SDP_MDIR_UNSET) {
+		sdp->media_direction = mdir;
+	}
+
+	return 0;
+}
+
+static const struct value_string fixed_payload_types[] = {
+	{ 0, "PCMU" },
+	{ 3, "GSM" },
+	{ 8, "PCMA" },
+	{ 18, "G729" },
+	{ 110, "GSM-EFR" },
+	{ 111, "GSM-HR-08" },
+	{ 112, "AMR" },
+	{ 113, "AMR-WB" },
+	{}
+};
+
+/* Parse a line like 'm=audio 16398 RTP/AVP 0 3 8 96 112', starting after the '=' */
+static int sdp_parse_media_description(struct osmo_sdp_msg *sdp, const char *src)
+{
+	unsigned int port;
+	int i;
+	const char *payload_type_str;
+	const char *line_end = get_line_end(src);
+	if (sscanf(src, "audio %u RTP/AVP", &port) < 1)
+		return -ENOTSUP;
+
+	if (port > 0xffff)
+		return -EINVAL;
+
+	sdp->rtp.port = port;
+
+	/* skip "audio 12345 RTP/AVP ", i.e. 3 spaces on */
+	payload_type_str = src;
+	for (i = 0; i < 3; i++) {
+		payload_type_str = strchr(payload_type_str, ' ');
+		if (!payload_type_str)
+			return -EINVAL;
+		while (*payload_type_str == ' ')
+			payload_type_str++;
+		if (payload_type_str >= line_end)
+			return -EINVAL;
+	}
+
+	/* Parse listing of payload type numbers after "RTP/AVP" */
+	while (payload_type_str < line_end) {
+		unsigned int payload_type;
+		struct osmo_sdp_codec *codec;
+		const char *encoding_name;
+		if (sscanf(payload_type_str, "%u", &payload_type) < 1)
+			return -EINVAL;
+
+		codec = find_or_create_payload_type(sdp, payload_type);
+
+		/* Fill in encoding name for fixed payload types */
+		encoding_name = get_value_string_or_null(fixed_payload_types, codec->payload_type);
+		if (encoding_name)
+			osmo_talloc_replace_string(codec, &codec->encoding_name, encoding_name);
+
+		payload_type_str = strchr(payload_type_str, ' ');
+		if (!payload_type_str)
+			payload_type_str = line_end;
+		while (*payload_type_str == ' ')
+			payload_type_str++;
+	}
+
+	return 0;
+}
+
+/* parse a line like 'c=IN IP4 192.168.11.151' starting after the '=' */
+static int sdp_parse_connection_info(struct osmo_sdp_msg *sdp, const char *src)
+{
+	char ipv[10];
+	char addr_str[INET6_ADDRSTRLEN];
+	if (sscanf(src, "IN %s %s", ipv, addr_str) < 2)
+		return -EINVAL;
+
+	if (strcmp(ipv, "IP4") && strcmp(ipv, "IP6"))
+		return -ENOTSUP;
+
+	return osmo_sockaddr_str_from_str(&sdp->rtp, addr_str, sdp->rtp.port);
+}
+
+static void next_token(struct token *t, const char *str, const char *end)
+{
+	t->start = str;
+	while (*t->start == ' ' && t->start < end)
+		t->start++;
+	t->end = t->start;
+	while (*t->end != ' ' && t->end < end)
+		t->end++;
+}
+
+/* parse a line like 'o=jdoe 3724394400 3724394405 IN IP4 198.51.100.1' starting after the '=' */
+static int sdp_parse_origin(struct osmo_sdp_msg *sdp, const char *src)
+{
+	struct token t;
+	char addr_str[INET6_ADDRSTRLEN + 1] = {};
+	const char *line_end = get_line_end(src);
+
+	next_token(&t, src, line_end);
+	token_copy(sdp, &sdp->origin.username, &t);
+
+	next_token(&t, t.end, line_end);
+	token_copy(sdp, &sdp->origin.sess_id, &t);
+
+	next_token(&t, t.end, line_end);
+	token_copy(sdp, &sdp->origin.sess_version, &t);
+
+	next_token(&t, t.end, line_end);
+	if (strncmp("IN", t.start, t.end - t.start))
+		return -ENOTSUP;
+
+	next_token(&t, t.end, line_end);
+	if (strncmp("IP4", t.start, t.end - t.start)
+	    && strncmp("IP6", t.start, t.end - t.start))
+		return -ENOTSUP;
+
+	next_token(&t, t.end, line_end);
+	osmo_strlcpy(addr_str, t.start, OSMO_MIN(sizeof(addr_str), t.end - t.start + 1));
+	return osmo_sockaddr_str_from_str(&sdp->origin.addr, addr_str, 0);
+}
+
+static int sdp_parse_session_name(struct osmo_sdp_msg *sdp, const char *src)
+{
+	const char *line_end = get_line_end(src);
+	if (sdp->session_name)
+		talloc_free(sdp->session_name);
+	if (line_end <= src)
+		sdp->session_name = NULL;
+	else
+		sdp->session_name = talloc_strndup(sdp, src, line_end - src);
+	return 0;
+}
+
+struct osmo_sdp_msg *osmo_sdp_msg_alloc(void *ctx)
+{
+	struct osmo_sdp_msg *sdp;
+	sdp = talloc_zero(ctx, struct osmo_sdp_msg);
+	sdp->codecs = osmo_sdp_codec_list_alloc(sdp);
+	return sdp;
+}
+
+/* Parse SDP string into struct osmo_sdp_msg. Return 0 on success, negative on error.
+ * Return a new osmo_sdp_msg instance allocated from ctx, or NULL on error.
+ * When NULL is returned and if err is non-NULL, details of the error are returned in err->*.
+ */
+struct osmo_sdp_msg *osmo_sdp_msg_decode(void *ctx, const char *src, struct osmo_sdp_err *err)
+{
+	struct osmo_sdp_msg *sdp;
+	const char *pos;
+
+	if (err)
+		*err = (struct osmo_sdp_err){};
+
+	sdp = osmo_sdp_msg_alloc(ctx);
+
+	for (pos = src; pos && *pos; pos++) {
+		char attrib;
+		int rc = 0;
+
+		if (*pos == '\r' || *pos == '\n')
+			continue;
+
+		/* Expecting only lines starting with 'X='. Not being too strict about it is probably alright. */
+		if (pos[1] != '=')
+			goto next_line;
+
+		attrib = *pos;
+		pos += 2;
+		switch (attrib) {
+			/* a=... */
+			case 'a':
+				rc = sdp_parse_attrib(sdp, pos);
+				break;
+			case 'm':
+				rc = sdp_parse_media_description(sdp, pos);
+				break;
+			case 'c':
+				rc = sdp_parse_connection_info(sdp, pos);
+				break;
+			case 'o':
+				rc = sdp_parse_origin(sdp, pos);
+				break;
+			case 's':
+				rc = sdp_parse_session_name(sdp, pos);
+				break;
+			default:
+				/* ignore any other parameters */
+				break;
+		}
+
+		if (rc) {
+			if (err) {
+				const char *line_end = get_line_end(pos);
+				/* shift back to include the 'x=' part as well */
+				pos -= 2;
+				*err = (struct osmo_sdp_err){
+					.rc = rc,
+					.at_input_str = pos,
+					.at_input_str_len = line_end - pos,
+				};
+			}
+			talloc_free(sdp);
+			return NULL;
+		}
+
+next_line:
+		pos = strstr(pos, "\r\n");
+		if (!pos)
+			break;
+	}
+
+	return sdp;
+}
+
+/*! Short single-line representation of an SDP message, convenient for logging.
+ * To obtain a valid SDP message, use osmo_sdp_msg_encode_buf() instead.
+ */
+int osmo_sdp_msg_to_str_buf(char *buf, size_t buflen, const struct osmo_sdp_msg *sdp, bool summarize)
+{
+       struct osmo_strbuf sb = { .buf = buf, .len = buflen };
+       if (!sdp) {
+               OSMO_STRBUF_PRINTF(sb, "NULL");
+               return sb.chars_needed;
+       }
+
+       OSMO_STRBUF_PRINTF(sb, OSMO_SOCKADDR_STR_FMT, OSMO_SOCKADDR_STR_FMT_ARGS(&sdp->rtp));
+       OSMO_STRBUF_PRINTF(sb, "{");
+       OSMO_STRBUF_APPEND(sb, osmo_sdp_codec_list_to_str_buf, sdp->codecs, summarize);
+       OSMO_STRBUF_PRINTF(sb, "}");
+       return sb.chars_needed;
+}
+
+char *osmo_sdp_msg_to_str_c(void *ctx, const struct osmo_sdp_msg *sdp, bool summarize)
+{
+       OSMO_NAME_C_IMPL(ctx, 128, "sdp_msg_to_str_c-ERROR", osmo_sdp_msg_to_str_buf, sdp, summarize)
+}

src/osmo-mgw/Makefile.am

@@ -25,12 +25,6 @@ osmo_mgw_SOURCES = \
 	$(NULL)
 
 osmo_mgw_LDADD = \
-	$(top_builddir)/src/libosmo-mgcp/libosmo-mgcp.a \
-	$(LIBOSMOCORE_LIBS) \
-	$(LIBOSMOVTY_LIBS) \
-	$(LIBOSMOGSM_LIBS) \
+	$(top_builddir)/src/libosmo-mgcp/libosmo-mgcp.la \
 	$(LIBOSMOCTRL_LIBS) \
-	$(LIBOSMONETIF_LIBS) \
-	$(LIBOSMOABIS_LIBS) \
-	$(LIBOSMOTRAU_LIBS) \
 	$(NULL)

tests/Makefile.am

@@ -1,6 +1,7 @@
 SUBDIRS = \
 	mgcp_client \
 	mgcp \
+	sdp \
 	$(NULL)
 
 # The `:;' works around a Bash 3.2 bug when the output is not writeable.

tests/mgcp/Makefile.am

@@ -34,7 +34,7 @@ mgcp_test_SOURCES = \
 	$(NULL)
 
 mgcp_test_LDADD = \
-	$(top_builddir)/src/libosmo-mgcp/libosmo-mgcp.a \
+	$(top_builddir)/src/libosmo-mgcp/libosmo-mgcp.la \
 	$(LIBOSMOCORE_LIBS) \
 	$(LIBOSMOVTY_LIBS) \
 	$(LIBOSMOGSM_LIBS) \

tests/mgcp/mgcp_test.c

@@ -103,7 +103,7 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16002 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX3A_RET \
 	"200 18983215 OK\r\n" \
@@ -115,7 +115,7 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16002 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX3_FMTP_RET \
 	"200 18983215 OK\r\n" \
@@ -127,40 +127,49 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16006 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX4_ADDR0000 \
 	"MDCX 18983216 1@mgw MGCP 1.0\r\n" \
-	"M: sendrecv\r" \
+	"M: sendrecv\r\n" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20, a:AMR, nt:IN\r\n" \
-	"\n" \
+	"\r\n" \
 	"v=0\r\n" \
 	"o=- %s 23 IN IP4 0.0.0.0\r\n" \
 	"c=IN IP4 0.0.0.0\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX4_ADDR0000_RET \
-	"527 18983216 FAIL\r\n"
+	"200 18983216 OK\r\n" \
+	"\r\n" \
+	"v=0\r\n" \
+	"o=- %s 23 IN IP4 0.0.0.0\r\n" \
+	"s=-\r\n" \
+	"c=IN IP4 0.0.0.0\r\n" \
+	"t=0 0\r\n" \
+	"m=audio 16002 RTP/AVP 99\r\n" \
+	"a=rtpmap:99 AMR/8000\r\n" \
+	"a=ptime:20\r\n"
 
 #define MDCX4 \
 	"MDCX 18983217 1@mgw MGCP 1.0\r\n" \
-	"M: sendrecv\r" \
+	"M: sendrecv\r\n" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20, a:AMR, nt:IN\r\n" \
-	"\n" \
+	"\r\n" \
 	"v=0\r\n" \
 	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
 	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX4_RET(Ident) \
 	"200 " Ident " OK\r\n" \
@@ -172,7 +181,7 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16002 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX4_RO_RET(Ident) \
 	"200 " Ident " OK\r\n" \
@@ -184,87 +193,87 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16002 RTP/AVP 112\r\n" \
 	"a=rtpmap:112 AMR\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX4_PT1 \
 	"MDCX 18983218 1@mgw MGCP 1.0\r\n" \
-	"M: SENDRECV\r" \
+	"M: SENDRECV\r\n" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20-40, a:AMR, nt:IN\r\n" \
-	"\n" \
+	"\r\n" \
 	"v=0\r\n" \
 	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
 	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX4_PT2 \
 	"MDCX 18983219 1@mgw MGCP 1.0\r\n" \
-	"M: sendrecv\r" \
+	"M: sendrecv\r\n" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20-20, a:AMR, nt:IN\r\n" \
-	"\n" \
+	"\r\n" \
 	"v=0\r\n" \
 	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
 	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX4_PT3 \
 	"MDCX 18983220 1@mgw MGCP 1.0\r\n" \
-	"M: sendrecv\r" \
+	"M: sendrecv\r\n" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: a:AMR, nt:IN\r\n" \
-	"\n" \
+	"\r\n" \
 	"v=0\r\n" \
 	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
 	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 /* Test different upper/lower case in options */
 #define MDCX4_PT4 \
 	"MDCX 18983221 1@mgw MGCP 1.0\r\n" \
-	"m: sendrecv\r" \
+	"m: sendrecv\r\n" \
 	"c: 2\r\n" \
 	"i: %s\r\n" \
 	"l: A:amr, NT:IN\r\n" \
-	"\n" \
+	"\r\n" \
 	"v=0\r\n" \
 	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
 	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX4_SO \
 	"MDCX 18983222 1@mgw MGCP 1.0\r\n" \
-	"M: sendonly\r" \
+	"M: sendonly\r\n" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20, a:AMR, nt:IN\r\n" \
-	"\n" \
+	"\r\n" \
 	"v=0\r\n" \
 	"o=- %s 23 IN IP4 5.6.7.8\r\n" \
 	"c=IN IP4 5.6.7.8\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 4441 RTP/AVP 99\r\n" \
 	"a=rtpmap:99 AMR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define MDCX4_RO \
 	"MDCX 18983223 1@mgw MGCP 1.0\r\n" \
-	"M: recvonly\r" \
+	"M: recvonly\r\n" \
 	"C: 2\r\n" \
 	"I: %s\r\n" \
 	"L: p:20, a:AMR, nt:IN\r\n"
@@ -297,7 +306,7 @@ static void test_strline(void)
 	"c=IN IP4 123.12.12.123\r\n" \
 	"m=audio 5904 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_RET \
 	"200 2 OK\r\n" \
@@ -310,7 +319,7 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16002 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_RET_NO_RTPMAP \
 	"200 2 OK\r\n" \
@@ -322,7 +331,7 @@ static void test_strline(void)
 	"c=IN IP4 0.0.0.0\r\n" \
 	"t=0 0\r\n" \
 	"m=audio 16002 RTP/AVP 97\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_FMTP_RET \
 	"200 2 OK\r\n" \
@@ -335,17 +344,17 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16006 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_ZYN \
-	"CRCX 2 1@mgw MGCP 1.0\r" \
-	"M: recvonly\r" \
+	"CRCX 2 1@mgw MGCP 1.0\r\n" \
+	"M: recvonly\r\n" \
 	"C: 2\r\n" \
-	"\n" \
-	"v=0\r" \
-	"c=IN IP4 123.12.12.123\r" \
-	"m=audio 5904 RTP/AVP 97\r" \
-	"a=rtpmap:97 GSM-EFR/8000\r"
+	"\r\n" \
+	"v=0\r\n" \
+	"c=IN IP4 123.12.12.123\r\n" \
+	"m=audio 5904 RTP/AVP 97\r\n" \
+	"a=rtpmap:97 GSM-EFR/8000\r\n"
 
 #define CRCX_ZYN_RET \
 	"200 2 OK\r\n" \
@@ -371,7 +380,7 @@ static void test_strline(void)
 	"c=IN IP4 123.12.12.123\r\n" \
 	"m=audio 5904 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_X_OSMO_IGN_RET \
 	"200 2 OK\r\n" \
@@ -384,7 +393,7 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16010 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_PORT_0 \
 	"CRCX 3 1@mgw MGCP 1.0\r\n" \
@@ -396,7 +405,7 @@ static void test_strline(void)
 	"c=IN IP4 123.12.12.123\r\n" \
 	"m=audio 0 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_PORT_0_RET \
 	"200 3 OK\r\n" \
@@ -409,7 +418,7 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16014 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_PORT_0_IUFP \
 	"CRCX 4 1@mgw MGCP 1.0\r\n" \
@@ -421,7 +430,7 @@ static void test_strline(void)
 	"c=IN IP4 123.12.12.123\r\n" \
 	"m=audio 0 RTP/AVP 96\r\n" \
 	"a=rtpmap:96 VND.3GPP.IUFP/16000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_PORT_0_IUFP_RET \
 	"200 4 OK\r\n" \
@@ -434,7 +443,45 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16016 RTP/AVP 96\r\n" \
 	"a=rtpmap:96 VND.3GPP.IUFP/16000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
+
+/* Do a CRCX in m=sendrecv */
+#define CRCX_PORT_0_IUFP_SENDRECV \
+	"CRCX 4 1@mgw MGCP 1.0\r\n" \
+	"M: sendrecv\r\n" \
+	"C: 2\r\n" \
+	"L: p:20\r\n" \
+	"\r\n" \
+	"v=0\r\n" \
+	"c=IN IP4 123.12.12.123\r\n" \
+	"m=audio 0 RTP/AVP 96\r\n" \
+	"a=rtpmap:96 VND.3GPP.IUFP/16000\r\n" \
+	"a=ptime:20\r\n"
+
+/* Do a CRCX using sendrecv mode in the SDP part */
+#define CRCX_PORT_0_IUFP_SENDRECV2 \
+	"CRCX 4 1@mgw MGCP 1.0\r\n" \
+	"C: 2\r\n" \
+	"L: p:20\r\n" \
+	"\r\n" \
+	"v=0\r\n" \
+	"c=IN IP4 123.12.12.123\r\n" \
+	"a=sendrecv\r\n" \
+	"m=audio 0 RTP/AVP 96\r\n" \
+	"a=rtpmap:96 VND.3GPP.IUFP/16000\r\n" \
+	"a=ptime:20\r\n"
+
+/* Do a CRCX entirely omitting a mode, i.e. implcit sendrecv */
+#define CRCX_PORT_0_IUFP_SENDRECV3 \
+	"CRCX 4 1@mgw MGCP 1.0\r\n" \
+	"C: 2\r\n" \
+	"L: p:20\r\n" \
+	"\r\n" \
+	"v=0\r\n" \
+	"c=IN IP4 123.12.12.123\r\n" \
+	"m=audio 0 RTP/AVP 96\r\n" \
+	"a=rtpmap:96 VND.3GPP.IUFP/16000\r\n" \
+	"a=ptime:20\r\n"
 
 #define DLCX \
 	"DLCX 7 1@mgw MGCP 1.0\r\n" \
@@ -491,7 +538,7 @@ static void test_strline(void)
 	"m=audio 5904 RTP/AVP 18 97\r\n" \
 	"a=rtpmap:18 G729/8000\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_MULT_2 \
 	"CRCX 2 2@mgw MGCP 1.0\r\n" \
@@ -506,7 +553,7 @@ static void test_strline(void)
 	"a=rtpmap:18 G729/8000\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
 	"a=rtpmap:101 FOO/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_MULT_3 \
 	"CRCX 2 3@mgw MGCP 1.0\r\n" \
@@ -521,7 +568,7 @@ static void test_strline(void)
 	"a=rtpmap:18 G729/8000\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
 	"a=rtpmap:101 FOO/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_MULT_4 \
 	"CRCX 2 4@mgw MGCP 1.0\r\n" \
@@ -536,7 +583,7 @@ static void test_strline(void)
 	"a=rtpmap:18 G729/8000\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
 	"a=rtpmap:101 FOO/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_MULT_GSM_EXACT \
 	"CRCX 259260421 5@mgw MGCP 1.0\r\n" \
@@ -600,7 +647,7 @@ static void test_strline(void)
 	"t=0 0\r\n" \
 	"m=audio 16012 RTP/AVP 111\r\n" \
 	"a=rtpmap:111 AMR/8000/1\r\n" \
-	"a=fmtp:111 octet-align=1\r\n" \
+	"a=fmtp:111 mode-change-capability=2; octet-align=1\r\n" \
 	"a=ptime:20\r\n"
 
 #define CRCX_NO_LCO_NO_SDP_RET \
@@ -625,7 +672,7 @@ static void test_strline(void)
 	"c=IN IP4 123.12.12.123\r\n" \
 	"m=audio 5904 RTP/AVP 97\r\n" \
 	"a=rtpmap:97 GSM-EFR/8000\r\n" \
-	"a=ptime:40\r\n"
+	"a=ptime:20\r\n"
 
 #define CRCX_NULL_RET "502 2 FAIL\r\n"
 
@@ -675,6 +722,9 @@ static const struct mgcp_test tests[] = {
 	{"RQNT_NULL", RQNT_NULL, RQNT_NULL_RET},
 	{"CRCX_PORT_0", CRCX_PORT_0, CRCX_PORT_0_RET, 97},
 	{"CRCX_PORT_0_IUFP", CRCX_PORT_0_IUFP, CRCX_PORT_0_IUFP_RET, 96},
+	{"CRCX_PORT_0_IUFP_SENDRECV", CRCX_PORT_0_IUFP_SENDRECV, CRCX_PORT_0_IUFP_RET, 96},
+	{"CRCX_PORT_0_IUFP_SENDRECV2", CRCX_PORT_0_IUFP_SENDRECV2, CRCX_PORT_0_IUFP_RET, 96},
+	{"CRCX_PORT_0_IUFP_SENDRECV3", CRCX_PORT_0_IUFP_SENDRECV3, CRCX_PORT_0_IUFP_RET, 96},
 };
 
 static const struct mgcp_test retransmit[] = {
@@ -893,6 +943,7 @@ static void test_messages(void)
 			}
 		} else if (check_response(msg->data, t->exp_resp) != 0) {
 			printf("%s failed.\n", t->name);
+			fflush(stdout);
 			OSMO_ASSERT(false);
 		}
 

tests/mgcp/mgcp_test.ok

@@ -73,7 +73,7 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 5904 RTP/AVP 97
 a=rtpmap:97 GSM-EFR/8000
-a=ptime:40
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -101,40 +101,42 @@ Testing MDCX4_ADDR000
 creating message from statically defined input:
 ---------8<---------
 MDCX 18983216 1@mgw MGCP 1.0
-M: sendrecv
+M: sendrecv
+C: 2
 I: %s
 L: p:20, a:AMR, nt:IN
-L: p:20, a:AMR, nt:IN
+
 v=0
 o=- %s 23 IN IP4 0.0.0.0
 c=IN IP4 0.0.0.0
 t=0 0
 m=audio 4441 RTP/AVP 99
 a=rtpmap:99 AMR/8000
-a=rtpmap:99 AMR/8000
+a=ptime:20
 
 ---------8<---------
 checking response:
-checking response:
+using message with patched conn_id for comparison
 Response matches our expectations.
-Response matches our expectations.
+(response contains a connection id)
 
 ================================================
 Testing MDCX4
 creating message from statically defined input:
 ---------8<---------
 MDCX 18983217 1@mgw MGCP 1.0
-MDCX 18983217 1@mgw MGCP 1.0
+M: sendrecv
+C: 2
 I: %s
 L: p:20, a:AMR, nt:IN
-I: %s
+
 v=0
 o=- %s 23 IN IP4 5.6.7.8
 c=IN IP4 5.6.7.8
 t=0 0
 m=audio 4441 RTP/AVP 99
 a=rtpmap:99 AMR/8000
-m=audio 4441 RTP/AVP 99
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -148,17 +150,18 @@ Testing MDCX4_PT1
 creating message from statically defined input:
 ---------8<---------
 MDCX 18983218 1@mgw MGCP 1.0
----------8<---------
+M: SENDRECV
+C: 2
 I: %s
 L: p:20-40, a:AMR, nt:IN
-C: 2
+
 v=0
 o=- %s 23 IN IP4 5.6.7.8
 c=IN IP4 5.6.7.8
 t=0 0
 m=audio 4441 RTP/AVP 99
 a=rtpmap:99 AMR/8000
-t=0 0
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -172,17 +175,18 @@ Testing MDCX4_PT2
 creating message from statically defined input:
 ---------8<---------
 MDCX 18983219 1@mgw MGCP 1.0
-creating message from statically defined input:
+M: sendrecv
+C: 2
 I: %s
 L: p:20-20, a:AMR, nt:IN
-M: sendrecv
+
 v=0
 o=- %s 23 IN IP4 5.6.7.8
 c=IN IP4 5.6.7.8
 t=0 0
 m=audio 4441 RTP/AVP 99
 a=rtpmap:99 AMR/8000
-c=IN IP4 5.6.7.8
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -196,17 +200,18 @@ Testing MDCX4_PT3
 creating message from statically defined input:
 ---------8<---------
 MDCX 18983220 1@mgw MGCP 1.0
-Testing MDCX4_PT3
+M: sendrecv
+C: 2
 I: %s
 L: a:AMR, nt:IN
-MDCX 18983220 1@mgw MGCP 1.0
+
 v=0
 o=- %s 23 IN IP4 5.6.7.8
 c=IN IP4 5.6.7.8
 t=0 0
 m=audio 4441 RTP/AVP 99
 a=rtpmap:99 AMR/8000
-o=- %s 23 IN IP4 5.6.7.8
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -220,17 +225,18 @@ Testing MDCX4_PT4
 creating message from statically defined input:
 ---------8<---------
 MDCX 18983221 1@mgw MGCP 1.0
-================================================
+m: sendrecv
+c: 2
 i: %s
 l: A:amr, NT:IN
----------8<---------
+
 v=0
 o=- %s 23 IN IP4 5.6.7.8
 c=IN IP4 5.6.7.8
 t=0 0
 m=audio 4441 RTP/AVP 99
 a=rtpmap:99 AMR/8000
-v=0
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -244,17 +250,18 @@ Testing MDCX4_SO
 creating message from statically defined input:
 ---------8<---------
 MDCX 18983222 1@mgw MGCP 1.0
-
+M: sendonly
+C: 2
 I: %s
 L: p:20, a:AMR, nt:IN
-creating message from statically defined input:
+
 v=0
 o=- %s 23 IN IP4 5.6.7.8
 c=IN IP4 5.6.7.8
 t=0 0
 m=audio 4441 RTP/AVP 99
 a=rtpmap:99 AMR/8000
-
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -267,7 +274,8 @@ Testing MDCX4_RO
 creating message from statically defined input:
 ---------8<---------
 MDCX 18983223 1@mgw MGCP 1.0
-(response contains a connection id)
+M: recvonly
+C: 2
 I: %s
 L: p:20, a:AMR, nt:IN
 
@@ -296,9 +304,15 @@ Response matches our expectations.
 Testing CRCX_ZYN
 creating message from statically defined input:
 ---------8<---------
-using message as statically defined for comparison
+CRCX 2 1@mgw MGCP 1.0
+M: recvonly
+C: 2
+
+v=0
+c=IN IP4 123.12.12.123
+m=audio 5904 RTP/AVP 97
+a=rtpmap:97 GSM-EFR/8000
 
-(response does not contain a connection id)
 ---------8<---------
 checking response:
 using message with patched conn_id for comparison
@@ -414,7 +428,7 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 5904 RTP/AVP 97
 a=rtpmap:97 GSM-EFR/8000
-================================================
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -479,7 +493,7 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 5904 RTP/AVP 97
 a=rtpmap:97 GSM-EFR/8000
-Testing CRCX
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -550,7 +564,7 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 5904 RTP/AVP 97
 a=rtpmap:97 GSM-EFR/8000
-================================================
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -612,7 +626,7 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 0 RTP/AVP 97
 a=rtpmap:97 GSM-EFR/8000
-================================================
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -633,7 +647,69 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 0 RTP/AVP 96
 a=rtpmap:96 VND.3GPP.IUFP/16000
-================================================
+a=ptime:20
+
+---------8<---------
+checking response:
+using message with patched conn_id for comparison
+Response matches our expectations.
+(response contains a connection id)
+
+================================================
+Testing CRCX_PORT_0_IUFP_SENDRECV
+creating message from statically defined input:
+---------8<---------
+CRCX 4 1@mgw MGCP 1.0
+M: sendrecv
+C: 2
+L: p:20
+
+v=0
+c=IN IP4 123.12.12.123
+m=audio 0 RTP/AVP 96
+a=rtpmap:96 VND.3GPP.IUFP/16000
+a=ptime:20
+
+---------8<---------
+checking response:
+using message with patched conn_id for comparison
+Response matches our expectations.
+(response contains a connection id)
+
+================================================
+Testing CRCX_PORT_0_IUFP_SENDRECV2
+creating message from statically defined input:
+---------8<---------
+CRCX 4 1@mgw MGCP 1.0
+C: 2
+L: p:20
+
+v=0
+c=IN IP4 123.12.12.123
+a=sendrecv
+m=audio 0 RTP/AVP 96
+a=rtpmap:96 VND.3GPP.IUFP/16000
+a=ptime:20
+
+---------8<---------
+checking response:
+using message with patched conn_id for comparison
+Response matches our expectations.
+(response contains a connection id)
+
+================================================
+Testing CRCX_PORT_0_IUFP_SENDRECV3
+creating message from statically defined input:
+---------8<---------
+CRCX 4 1@mgw MGCP 1.0
+C: 2
+L: p:20
+
+v=0
+c=IN IP4 123.12.12.123
+m=audio 0 RTP/AVP 96
+a=rtpmap:96 VND.3GPP.IUFP/16000
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -654,7 +730,7 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 5904 RTP/AVP 97
 a=rtpmap:97 GSM-EFR/8000
-================================================
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -672,7 +748,7 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 5904 RTP/AVP 97
 a=rtpmap:97 GSM-EFR/8000
-Response matches our expectations.
+a=ptime:20
 
 ---------8<---------
 checking response:
@@ -784,7 +860,7 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 5904 RTP/AVP 97
 a=rtpmap:97 GSM-EFR/8000
-Response matches our expectations.
+a=ptime:20
 
 ---------8<---------
 creating message from statically defined input:
@@ -1238,7 +1314,7 @@ c=IN IP4 123.12.12.123
 m=audio 5904 RTP/AVP 18 97
 a=rtpmap:18 G729/8000
 a=rtpmap:97 GSM-EFR/8000
-creating message from statically defined input:
+a=ptime:20
 
 ---------8<---------
 creating message from statically defined input:
@@ -1255,7 +1331,7 @@ m=audio 5904 RTP/AVP 18 97 101
 a=rtpmap:18 G729/8000
 a=rtpmap:97 GSM-EFR/8000
 a=rtpmap:101 FOO/8000
----------8<---------
+a=ptime:20
 
 ---------8<---------
 creating message from statically defined input:
@@ -1272,7 +1348,7 @@ m=audio 5904 RTP/AVP
 a=rtpmap:18 G729/8000
 a=rtpmap:97 GSM-EFR/8000
 a=rtpmap:101 FOO/8000
----------8<---------
+a=ptime:20
 
 ---------8<---------
 creating message from statically defined input:
@@ -1289,7 +1365,7 @@ m=audio 5904 RTP/AVP 18
 a=rtpmap:18 G729/8000
 a=rtpmap:97 GSM-EFR/8000
 a=rtpmap:101 FOO/8000
----------8<---------
+a=ptime:20
 
 ---------8<---------
 creating message from statically defined input:
@@ -1371,7 +1447,7 @@ v=0
 c=IN IP4 123.12.12.123
 m=audio 5904 RTP/AVP 97
 a=rtpmap:97 GSM-EFR/8000
-Testing no sequence flow on initial packet
+a=ptime:20
 
 ---------8<---------
 checking response:

tests/sdp/Makefile.am

@@ -0,0 +1,62 @@
+AM_CPPFLAGS = \
+	$(all_includes) \
+	-I$(top_srcdir)/include \
+	-I$(top_builddir)/include \
+	-I$(top_srcdir) \
+	$(NULL)
+
+AM_CFLAGS = \
+	-Wall \
+	-ggdb3 \
+	$(LIBOSMOCORE_CFLAGS) \
+	$(COVERAGE_CFLAGS) \
+	$(NULL)
+
+AM_LDFLAGS = \
+	$(COVERAGE_LDFLAGS) \
+	-no-install \
+	$(NULL)
+
+EXTRA_DIST = \
+	sdp_fmtp_test.ok \
+	sdp_fmtp_test.err \
+	sdp_codec_test.ok \
+	sdp_codec_test.err \
+	$(NULL)
+
+check_PROGRAMS = \
+	sdp_fmtp_test \
+	sdp_codec_test \
+	sdp_msg_test \
+	$(NULL)
+
+sdp_fmtp_test_SOURCES = \
+	sdp_fmtp_test.c \
+	$(NULL)
+
+sdp_fmtp_test_LDADD = \
+	$(top_builddir)/src/libosmo-sdp/libosmo-sdp.la \
+	$(NULL)
+
+sdp_codec_test_SOURCES = \
+	sdp_codec_test.c \
+	$(NULL)
+
+sdp_codec_test_LDADD = \
+	$(top_builddir)/src/libosmo-sdp/libosmo-sdp.la \
+	$(LIBOSMOCORE_LIBS) \
+	$(NULL)
+
+sdp_msg_test_SOURCES = \
+	sdp_msg_test.c \
+	$(NULL)
+
+sdp_msg_test_LDADD = \
+	$(top_builddir)/src/libosmo-sdp/libosmo-sdp.la \
+	$(LIBOSMOCORE_LIBS) \
+	$(NULL)
+
+update_exp:
+	$(builddir)/sdp_fmtp_test >$(srcdir)/sdp_fmtp_test.ok 2>$(srcdir)/sdp_fmtp_test.err
+	$(builddir)/sdp_codec_test >$(srcdir)/sdp_codec_test.ok 2>$(srcdir)/sdp_codec_test.err
+	$(builddir)/sdp_msg_test >$(srcdir)/sdp_msg_test.ok 2>$(srcdir)/sdp_msg_test.err

tests/sdp/sdp_codec_test.c

@@ -0,0 +1,645 @@
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/linuxlist.h>
+
+#include <osmocom/sdp/sdp_codec_list.h>
+#include <osmocom/sdp/fmtp.h>
+
+void *test_ctx = NULL;
+
+static void report_callback(const void *ptr, int depth, int max_depth, int is_ref, void *priv)
+{
+        const char *name = talloc_get_name(ptr);
+	printf(" |%*s%3zu %s\n", depth, "", talloc_total_blocks(ptr), name);
+}
+
+/* Print a talloc report that is reproducible for test output verification. It contains no pointer addresses. */
+#define report(CTX) _report(CTX, #CTX)
+static void _report(void *ctx, const char *label)
+{
+	fflush(stdout);
+	fflush(stderr);
+	printf("%s\n", label);
+        talloc_report_depth_cb(ctx, 0, 100, report_callback, NULL);
+	fflush(stdout);
+}
+
+struct codec_test {
+	struct osmo_sdp_codec set;
+	int expect_rc;
+	const char *expect_str;
+	bool expect_is_set;
+};
+
+struct codec_test codec_tests[] = {
+	{
+		.set = { 23, "encoding-name", 8000, NULL },
+		.expect_str = "encoding-name#23",
+		.expect_is_set = true,
+	},
+	{
+		.set = { 112, "AMR", 8000, "octet-align=1;mode-set=0,2,4" },
+		.expect_str = "AMR:octet-align=1;mode-set=0,2,4#112",
+		.expect_is_set = true,
+	},
+	{
+		.set = { 96, "AMR", 8000, "mode-set=0,2,4;octet-align=1" },
+		.expect_str = "AMR:mode-set=0,2,4;octet-align=1#96",
+		.expect_is_set = true,
+	},
+	{
+		.set = { 114, "AMR", 8000, "mode-set=0,2,4" },
+		.expect_str = "AMR:mode-set=0,2,4#114",
+		.expect_is_set = true,
+	},
+	{
+		.set = { 97, "AMR", 8000, "mode-set=0,2,4;octet-align=0" },
+		.expect_str = "AMR:mode-set=0,2,4;octet-align=0#97",
+		.expect_is_set = true,
+	},
+	{
+		.set = { 98, "AMR", 8000, "octet-align=1" },
+		.expect_str = "AMR:octet-align=1#98",
+		.expect_is_set = true,
+	},
+	{
+		.set = { 96, "AMR-WB", 16000 },
+		.expect_str = "AMR-WB/16000#96",
+		.expect_is_set = true,
+	},
+	{
+		.set = { 3, "GSM", 8000 },
+		.expect_str = "GSM#3",
+		.expect_is_set = true,
+	},
+	{
+		.set = { },
+		.expect_str = "/0#0",
+		.expect_is_set = false,
+	},
+	{
+		.set = { 112, NULL, 8000, "octet-align=1" },
+		.expect_str = ":octet-align=1#112",
+		.expect_is_set = false,
+	},
+	{
+		.set = { 112, "", 8000, "octet-align=1" },
+		.expect_str = ":octet-align=1#112",
+		.expect_is_set = false,
+	},
+};
+
+void test_codec(void)
+{
+	void *ctx = talloc_named_const(test_ctx, 0, __func__);
+
+	struct codec_test *t;
+	struct codec_test *t2;
+
+	printf("\n\n--- %s()\n", __func__);
+	printf("- osmo_sdp_codec_set():\n");
+	for (t = codec_tests; (t - codec_tests) < ARRAY_SIZE(codec_tests); t++) {
+		struct osmo_sdp_codec *codec = osmo_sdp_codec_alloc(ctx);
+		char *str;
+		bool is_set;
+
+		osmo_sdp_codec_set(codec, t->set.payload_type, t->set.encoding_name, t->set.rate, t->set.fmtp);
+
+		str = osmo_sdp_codec_to_str_c(ctx, codec);
+		printf("osmo_sdp_codec_set [%d] '%s'\n", (int)(t - codec_tests), str);
+		if (strcmp(str, t->expect_str))
+			printf("  *** ERROR: expected '%s'\n", t->expect_str);
+
+		if (!osmo_sdp_codec_cmp(codec, &t->set, &osmo_sdp_codec_cmp_exact))
+			printf("  osmo_sdp_codec_cmp() ok\n");
+		else
+			printf("  osmo_sdp_codec_cmp() *** ERROR: mismatches original values\n");
+
+		is_set = osmo_sdp_codec_is_set(codec);
+		printf("  osmo_sdp_codec_is_set() = %s\n", is_set ? "true" : "false");
+		if (is_set != t->expect_is_set)
+			printf("    *** ERROR: expected is_set = %s\n", t->expect_is_set ? "true" : "false");
+
+		if (is_set != osmo_sdp_codec_is_set(&t->set))
+			printf("    *** ERROR: is_set(copy) != is_set(orig)\n");
+
+		talloc_free(str);
+		talloc_free(codec);
+		if (talloc_total_blocks(ctx) != 1)
+			printf("  *** ERROR: ctx has %zu items, should be 1\n", talloc_total_blocks(ctx));
+	}
+
+	printf("\n- osmo_sdp_codec_cmp(equivalent):\n");
+	for (t = codec_tests; (t - codec_tests) < ARRAY_SIZE(codec_tests); t++) {
+		for (t2 = codec_tests; (t2 - codec_tests) < ARRAY_SIZE(codec_tests); t2++) {
+			int cmp = osmo_sdp_codec_cmp(&t->set, &t2->set, &osmo_sdp_codec_cmp_equivalent);
+			int reverse_cmp = osmo_sdp_codec_cmp(&t2->set, &t->set, &osmo_sdp_codec_cmp_equivalent);
+			printf("  %s %s %s %s %s\n",
+			       osmo_sdp_codec_to_str_c(ctx, &t->set),
+			       (cmp == 0) ? "=="
+			       : ((cmp < 0) ? "<" : ">"),
+			       osmo_sdp_codec_to_str_c(ctx, &t2->set),
+			       (reverse_cmp == 0) ? "=="
+			       : ((reverse_cmp < 0) ? "<" : ">"),
+			       osmo_sdp_codec_to_str_c(ctx, &t->set));
+
+			if (reverse_cmp != -cmp)
+				printf("    *** ERROR: osmo_sdp_codec_cmp(reverse args) == %d, expected %d\n",
+				       reverse_cmp, -cmp);
+
+			talloc_free_children(ctx);
+		}
+	}
+
+	printf("\n- osmo_sdp_codec_from_str():\n");
+	for (t = codec_tests; (t - codec_tests) < ARRAY_SIZE(codec_tests); t++) {
+		struct osmo_sdp_codec *codec = osmo_sdp_codec_alloc(ctx);
+		int rc = osmo_sdp_codec_from_str(codec, t->expect_str, -1);
+		printf("  osmo_sdp_codec_from_str('%s') rc=%d",
+		       t->expect_str, rc);
+		if (!rc) {
+			printf(" res=%s", osmo_sdp_codec_to_str_c(ctx, codec));
+			rc = osmo_sdp_codec_cmp(codec, &t->set, &osmo_sdp_codec_cmp_exact);
+			if (rc)
+				printf(" *** ERROR: osmo_sdp_codec_cmp(res,orig) = %d", rc);
+		}
+		printf("\n");
+		talloc_free_children(ctx);
+	}
+
+	talloc_free(ctx);
+}
+
+void test_codec_list(void)
+{
+	void *list_ctx = talloc_named_const(test_ctx, 0, __func__);
+	void *print_ctx = talloc_named_const(test_ctx, 0, "print");
+	int i;
+	int rc;
+	struct osmo_sdp_codec *codec;
+
+	const struct osmo_sdp_codec all_codecs[] = {
+		{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+		{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+		{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+	};
+
+	struct osmo_sdp_codec_list *codec_list;
+
+	printf("\n\n--- %s()\n", __func__);
+
+	codec_list = osmo_sdp_codec_list_alloc(list_ctx);
+	printf("osmo_sdp_codec_list_first() = %s\n",
+	       osmo_sdp_codec_to_str_c(print_ctx, osmo_sdp_codec_list_first(codec_list)));
+	report(list_ctx);
+
+	for (i = 0; i < ARRAY_SIZE(all_codecs); i++) {
+		struct osmo_sdp_codec *added = osmo_sdp_codec_list_add(codec_list, &all_codecs[i], NULL, false);
+		printf("[%d] osmo_sdp_codec_list_add(%s)\n", i, osmo_sdp_codec_to_str_c(print_ctx, added));
+	}
+
+	i = 0;
+	osmo_sdp_codec_list_foreach(codec, codec_list) {
+		printf("codec_list[%d] = %s\n", i++, osmo_sdp_codec_to_str_c(print_ctx, codec));
+	}
+	printf("osmo_sdp_codec_list_first() = %s\n",
+	       osmo_sdp_codec_to_str_c(print_ctx, osmo_sdp_codec_list_first(codec_list)));
+	report(list_ctx);
+
+	printf("osmo_sdp_codec_list_to_str_c(summarize=true):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, true));
+	printf("osmo_sdp_codec_list_to_str_c(summarize=false):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, false));
+
+	printf("\n");
+	printf("- add same entries again with once=exact, nothing should change\n");
+	for (i = 0; i < ARRAY_SIZE(all_codecs); i++) {
+		struct osmo_sdp_codec *added = osmo_sdp_codec_list_add(codec_list, &all_codecs[i],
+								       &osmo_sdp_codec_cmp_exact, false);
+		printf("[] osmo_sdp_codec_list_add(%s)\n", osmo_sdp_codec_to_str_c(print_ctx, added));
+	}
+	i = 0;
+	osmo_sdp_codec_list_foreach(codec, codec_list) {
+		printf("codec_list[%d] = %s\n", i++, osmo_sdp_codec_to_str_c(print_ctx, codec));
+	}
+	report(list_ctx);
+
+	printf("osmo_sdp_codec_list_to_str_c(summarize=true):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, true));
+	printf("osmo_sdp_codec_list_to_str_c(summarize=false):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, false));
+
+	printf("\n");
+	printf("- add same entries again with once=NULL, duplicates are added\n");
+	for (i = 0; i < ARRAY_SIZE(all_codecs); i++) {
+		struct osmo_sdp_codec *added = osmo_sdp_codec_list_add(codec_list, &all_codecs[i], NULL, false);
+		printf("[] osmo_sdp_codec_list_add(%s)\n", osmo_sdp_codec_to_str_c(print_ctx, added));
+	}
+	i = 0;
+	osmo_sdp_codec_list_foreach(codec, codec_list) {
+		printf("codec_list[%d] = %s\n", i++, osmo_sdp_codec_to_str_c(print_ctx, codec));
+	}
+	report(list_ctx);
+
+	printf("osmo_sdp_codec_list_to_str_c(summarize=true):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, true));
+	printf("osmo_sdp_codec_list_to_str_c(summarize=false):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, false));
+
+	printf("\n");
+	printf("- add same entries again with once=NULL,pick_unused_pt_nr=true, duplicates are added with new #nr\n");
+	for (i = 0; i < ARRAY_SIZE(all_codecs); i++) {
+		struct osmo_sdp_codec *added = osmo_sdp_codec_list_add(codec_list, &all_codecs[i], NULL, true);
+		printf("[] osmo_sdp_codec_list_add(%s)\n", osmo_sdp_codec_to_str_c(print_ctx, added));
+	}
+	i = 0;
+	osmo_sdp_codec_list_foreach(codec, codec_list) {
+		printf("codec_list[%d] = %s\n", i++, osmo_sdp_codec_to_str_c(print_ctx, codec));
+	}
+	report(list_ctx);
+
+	printf("osmo_sdp_codec_list_to_str_c(summarize=true):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, true));
+	printf("osmo_sdp_codec_list_to_str_c(summarize=false):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, false));
+
+	printf("\n");
+	printf("- remove all 'GSM#3' entries, with osmo_sdp_codec_cmp_exact\n");
+	rc = osmo_sdp_codec_list_remove(codec_list, &all_codecs[1], &osmo_sdp_codec_cmp_exact);
+	printf("  osmo_sdp_codec_list_remove() = %d\n", rc);
+	i = 0;
+	osmo_sdp_codec_list_foreach(codec, codec_list) {
+		printf("codec_list[%d] = %s\n", i++, osmo_sdp_codec_to_str_c(print_ctx, codec));
+	}
+	report(list_ctx);
+
+	printf("osmo_sdp_codec_list_to_str_c(summarize=true):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, true));
+	printf("osmo_sdp_codec_list_to_str_c(summarize=false):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, false));
+
+	printf("- remove all 'GSM' entries, with osmo_sdp_codec_cmp_equivalent\n");
+	rc = osmo_sdp_codec_list_remove(codec_list, &all_codecs[1], &osmo_sdp_codec_cmp_equivalent);
+	printf("  osmo_sdp_codec_list_remove() = %d\n", rc);
+	i = 0;
+	osmo_sdp_codec_list_foreach(codec, codec_list) {
+		printf("codec_list[%d] = %s\n", i++, osmo_sdp_codec_to_str_c(print_ctx, codec));
+	}
+	report(list_ctx);
+
+	printf("osmo_sdp_codec_list_to_str_c(summarize=true):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, true));
+	printf("osmo_sdp_codec_list_to_str_c(summarize=false):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, false));
+
+	rc = osmo_sdp_codec_list_move_to_first(codec_list, &all_codecs[0], &osmo_sdp_codec_cmp_equivalent);
+	printf("- osmo_sdp_codec_list_move_to_first('%s', equivalent) = %d\n",
+	       osmo_sdp_codec_to_str_c(print_ctx, &all_codecs[0]), rc);
+	i = 0;
+	osmo_sdp_codec_list_foreach(codec, codec_list) {
+		printf("codec_list[%d] = %s\n", i++, osmo_sdp_codec_to_str_c(print_ctx, codec));
+	}
+	report(list_ctx);
+
+	printf("osmo_sdp_codec_list_to_str_c(summarize=true):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, true));
+	printf("osmo_sdp_codec_list_to_str_c(summarize=false):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, false));
+
+
+	printf("- osmo_sdp_codec_list_free_items()\n");
+	osmo_sdp_codec_list_free_items(codec_list);
+	i = 0;
+	osmo_sdp_codec_list_foreach(codec, codec_list) {
+		printf("codec_list[%d] = %s\n", i++, osmo_sdp_codec_to_str_c(print_ctx, codec));
+	}
+	printf("  %d entries\n", i);
+	report(list_ctx);
+
+	printf("osmo_sdp_codec_list_to_str_c(summarize=true):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, true));
+	printf("osmo_sdp_codec_list_to_str_c(summarize=false):\n '%s'\n",
+	       osmo_sdp_codec_list_to_str_c(print_ctx, codec_list, false));
+
+	talloc_free(print_ctx);
+	talloc_free(list_ctx);
+}
+
+static struct osmo_sdp_codec_list *init_codec_list(void *ctx, const struct osmo_sdp_codec *init_array)
+{
+	struct osmo_sdp_codec_list *dst = osmo_sdp_codec_list_alloc(ctx);
+	for (; osmo_sdp_codec_is_set(init_array); init_array++)
+		osmo_sdp_codec_list_add(dst, init_array, NULL, false);
+	return dst;
+}
+
+void test_codec_list_cmp(void)
+{
+	void *ctx = talloc_named_const(test_ctx, 0, __func__);
+	void *print_ctx = talloc_named_const(test_ctx, 0, "print");
+	int i;
+
+	const struct osmo_sdp_codec codec_a[] = {
+		{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+		{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+		{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		{}
+	};
+
+	const struct osmo_sdp_codec codec_b[][5] = {
+		/* same */
+		{
+			{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		},
+
+		/* different payload_type */
+		{
+			{ .payload_type = 96, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		},
+
+		/* AMR fmtp in different order */
+		{
+			{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "mode-set=0,2,4;octet-align=1" },
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		},
+
+		/* different AMR mode-set */
+		{
+			{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=7" },
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		},
+
+		/* empty AMR mode-set */
+		{
+			{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1" },
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		},
+
+		/* different AMR octet-align */
+		{
+			{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=0;mode-set=0,2,4" },
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		},
+
+		/* omitted AMR octet-align is identical to octet-align=0 */
+		{
+			{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "mode-set=0,2,4" },
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		},
+
+		/* different order */
+		{
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+			{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+		},
+
+		/* one less item */
+		{
+			{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+		},
+
+		/* one more item */
+		{
+			{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+			{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+			{ .payload_type = 110, .encoding_name = "GSM-EFR", .rate = 8000 },
+		},
+	};
+
+	const struct osmo_sdp_codec_cmp_flags *test_cmpf[] = {
+		&osmo_sdp_codec_cmp_name,
+		&osmo_sdp_codec_cmp_equivalent,
+		&osmo_sdp_codec_cmp_exact,
+	};
+
+	printf("\n\n--- %s()\n", __func__);
+
+	for (i = 0; i < ARRAY_SIZE(codec_b); i++) {
+		struct osmo_sdp_codec_list *list_a = init_codec_list(ctx, codec_a);
+		struct osmo_sdp_codec_list *list_b = init_codec_list(ctx, codec_b[i]);
+		int j;
+
+		printf("A = %s\n", osmo_sdp_codec_list_to_str_c(print_ctx, list_a, false));
+		printf("B = %s\n", osmo_sdp_codec_list_to_str_c(print_ctx, list_b, false));
+
+		for (j = 0; j < ARRAY_SIZE(test_cmpf); j++) {
+			const struct osmo_sdp_codec_cmp_flags *cmpf = test_cmpf[j];
+			int cmp = osmo_sdp_codec_list_cmp(list_a, list_b, cmpf);
+			int reverse_cmp = osmo_sdp_codec_list_cmp(list_b, list_a, cmpf);
+			printf("  cmpf[%d]: payload_type=%s rate=%s fmtp=%d: A %s B %s A\n",
+			       j,
+			       cmpf->payload_type ? "true" : "false",
+			       cmpf->rate ? "true" : "false",
+			       cmpf->fmtp,
+			       (cmp == 0) ? "=="
+				       : ((cmp < 0) ? "<" : ">"),
+			       (reverse_cmp == 0) ? "=="
+				       : ((reverse_cmp < 0) ? "<" : ">"));
+
+			if (reverse_cmp != -cmp)
+				printf("    *** ERROR: osmo_sdp_codec_list_cmp(reverse args) == %d, expected %d\n",
+				       reverse_cmp, -cmp);
+		}
+
+		talloc_free(list_a);
+		talloc_free(list_b);
+
+		if (talloc_total_blocks(ctx) != 1) {
+			printf("ERROR: memleak:\n");
+			report(ctx);
+		}
+		printf("\n");
+
+		talloc_free_children(print_ctx);
+	}
+
+	talloc_free(print_ctx);
+	talloc_free(ctx);
+}
+
+void test_codec_list_intersection(void)
+{
+	void *ctx = talloc_named_const(test_ctx, 0, __func__);
+	void *print_ctx = talloc_named_const(test_ctx, 0, "print");
+	int i;
+
+	const struct osmo_sdp_codec codec_a[] = {
+		{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+		{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+		{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		{}
+	};
+
+	const struct osmo_sdp_codec codec_b[][5] = {
+		/* same */
+		{
+			{ .payload_type = 96, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+			{ .payload_type = 97, .encoding_name = "GSM", .rate = 8000 },
+			{ .payload_type = 98, .encoding_name = "GSM-HR-08", .rate = 8000 },
+		},
+
+		/* same in different order */
+		{
+			{ .payload_type = 98, .encoding_name = "GSM-HR-08", .rate = 8000 },
+			{ .payload_type = 96, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+			{ .payload_type = 97, .encoding_name = "GSM", .rate = 8000 },
+		},
+
+		/* two matches */
+		{
+			{ .payload_type = 98, .encoding_name = "GSM-HR-08", .rate = 8000 },
+			{ .payload_type = 110, .encoding_name = "GSM-EFR", .rate = 8000 },
+			{ .payload_type = 97, .encoding_name = "GSM", .rate = 8000 },
+		},
+
+		/* no match */
+		{
+			{ .payload_type = 97, .encoding_name = "AMR-WB", .rate = 16000 },
+			{ .payload_type = 98, .encoding_name = "FOO", .rate = 8000 },
+			{ .payload_type = 110, .encoding_name = "GSM-EFR", .rate = 8000 },
+		},
+
+	};
+
+	printf("\n\n--- %s()\n", __func__);
+
+	for (i = 0; i < ARRAY_SIZE(codec_b); i++) {
+		struct osmo_sdp_codec_list *list_a = init_codec_list(ctx, codec_a);
+		struct osmo_sdp_codec_list *list_b = init_codec_list(ctx, codec_b[i]);
+
+		printf("A = %s\n", osmo_sdp_codec_list_to_str_c(print_ctx, list_a, false));
+		printf("B = %s\n", osmo_sdp_codec_list_to_str_c(print_ctx, list_b, false));
+
+		osmo_sdp_codec_list_intersection(list_a, list_b, &osmo_sdp_codec_cmp_equivalent, false);
+		printf("osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=false)\n = %s\n",
+		       osmo_sdp_codec_list_to_str_c(print_ctx, list_a, false));
+
+		talloc_free(list_a);
+		list_a = init_codec_list(ctx, codec_a);
+
+		osmo_sdp_codec_list_intersection(list_a, list_b, &osmo_sdp_codec_cmp_equivalent, true);
+		printf("osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=true)\n = %s\n",
+		       osmo_sdp_codec_list_to_str_c(print_ctx, list_a, false));
+
+		talloc_free(list_a);
+		list_a = init_codec_list(ctx, codec_a);
+
+		osmo_sdp_codec_list_intersection(list_b, list_a, &osmo_sdp_codec_cmp_equivalent, false);
+		printf("osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=false)\n = %s\n",
+		       osmo_sdp_codec_list_to_str_c(print_ctx, list_b, false));
+
+		talloc_free(list_a);
+		list_a = init_codec_list(ctx, codec_a);
+
+		osmo_sdp_codec_list_intersection(list_b, list_a, &osmo_sdp_codec_cmp_equivalent, true);
+		printf("osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=true)\n = %s\n",
+		       osmo_sdp_codec_list_to_str_c(print_ctx, list_b, false));
+
+		talloc_free(list_a);
+		talloc_free(list_b);
+
+		if (talloc_total_blocks(ctx) != 1) {
+			printf("ERROR: memleak:\n");
+			report(ctx);
+		}
+		printf("\n");
+
+		talloc_free_children(print_ctx);
+	}
+
+	talloc_free(print_ctx);
+	talloc_free(ctx);
+}
+
+
+struct my_obj {
+	struct osmo_sdp_codec *codec;
+	struct osmo_sdp_codec_list *codec_list;
+};
+
+struct my_obj *my_obj_alloc(void *ctx)
+{
+	struct my_obj *o = talloc_zero(ctx, struct my_obj);
+	o->codec_list = osmo_sdp_codec_list_alloc(o);
+	return o;
+}
+
+void test_obj_members(void)
+{
+	void *ctx = talloc_named_const(test_ctx, 0, __func__);
+	void *print_ctx = talloc_named_const(test_ctx, 0, "print");
+	int i;
+	struct osmo_sdp_codec *codec;
+
+	struct my_obj *o;
+
+	printf("\n\n--- %s()\n", __func__);
+	o = my_obj_alloc(ctx);
+
+	o->codec = osmo_sdp_codec_alloc(o);
+	osmo_sdp_codec_set(o->codec, 96, "AMR", 8000, "octet-align=1");
+
+	printf("o->codec = %s\n", osmo_sdp_codec_to_str_c(print_ctx, o->codec));
+	report(ctx);
+
+	osmo_sdp_codec_list_add(o->codec_list, o->codec, false, false);
+	osmo_sdp_codec_list_add(o->codec_list, o->codec, false, true);
+	i = 0;
+	osmo_sdp_codec_list_foreach(codec, o->codec_list) {
+		printf("o->codec_list[%d] = %s\n", i++, osmo_sdp_codec_to_str_c(print_ctx, codec));
+	}
+
+	report(ctx);
+	printf("talloc_free(o)\n");
+	talloc_free(o);
+	report(ctx);
+	talloc_free(ctx);
+	talloc_free(print_ctx);
+}
+
+typedef void (*test_func_t)(void);
+test_func_t test_func[] = {
+	test_codec,
+	test_codec_list,
+	test_codec_list_cmp,
+	test_codec_list_intersection,
+	test_obj_members,
+};
+
+int main(void)
+{
+	int i;
+	test_ctx = talloc_named_const(NULL, 0, "sdp_codec_test");
+
+	for (i = 0; i < ARRAY_SIZE(test_func); i++) {
+
+		test_func[i]();
+
+		if (talloc_total_blocks(test_ctx) != 1) {
+			talloc_report_full(test_ctx, stderr);
+			printf("ERROR after test %d: memory leak\n", i);
+			return -1;
+		}
+	}
+
+	talloc_free(test_ctx);
+	return 0;
+}

tests/sdp/sdp_codec_test.ok

@@ -0,0 +1,538 @@
+
+
+--- test_codec()
+- osmo_sdp_codec_set():
+osmo_sdp_codec_set [0] 'encoding-name#23'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = true
+osmo_sdp_codec_set [1] 'AMR:octet-align=1;mode-set=0,2,4#112'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = true
+osmo_sdp_codec_set [2] 'AMR:mode-set=0,2,4;octet-align=1#96'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = true
+osmo_sdp_codec_set [3] 'AMR:mode-set=0,2,4#114'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = true
+osmo_sdp_codec_set [4] 'AMR:mode-set=0,2,4;octet-align=0#97'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = true
+osmo_sdp_codec_set [5] 'AMR:octet-align=1#98'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = true
+osmo_sdp_codec_set [6] 'AMR-WB/16000#96'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = true
+osmo_sdp_codec_set [7] 'GSM#3'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = true
+osmo_sdp_codec_set [8] '/0#0'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = false
+osmo_sdp_codec_set [9] ':octet-align=1#112'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = false
+osmo_sdp_codec_set [10] ':octet-align=1#112'
+  osmo_sdp_codec_cmp() ok
+  osmo_sdp_codec_is_set() = false
+
+- osmo_sdp_codec_cmp(equivalent):
+  encoding-name#23 == encoding-name#23 == encoding-name#23
+  encoding-name#23 > AMR:octet-align=1;mode-set=0,2,4#112 < encoding-name#23
+  encoding-name#23 > AMR:mode-set=0,2,4;octet-align=1#96 < encoding-name#23
+  encoding-name#23 > AMR:mode-set=0,2,4#114 < encoding-name#23
+  encoding-name#23 > AMR:mode-set=0,2,4;octet-align=0#97 < encoding-name#23
+  encoding-name#23 > AMR:octet-align=1#98 < encoding-name#23
+  encoding-name#23 > AMR-WB/16000#96 < encoding-name#23
+  encoding-name#23 > GSM#3 < encoding-name#23
+  encoding-name#23 > /0#0 < encoding-name#23
+  encoding-name#23 > :octet-align=1#112 < encoding-name#23
+  encoding-name#23 > :octet-align=1#112 < encoding-name#23
+  AMR:octet-align=1;mode-set=0,2,4#112 < encoding-name#23 > AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 == AMR:octet-align=1;mode-set=0,2,4#112 == AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 == AMR:mode-set=0,2,4;octet-align=1#96 == AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 > AMR:mode-set=0,2,4#114 < AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 > AMR:mode-set=0,2,4;octet-align=0#97 < AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 == AMR:octet-align=1#98 == AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 < AMR-WB/16000#96 > AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 < GSM#3 > AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 > /0#0 < AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 > :octet-align=1#112 < AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:octet-align=1;mode-set=0,2,4#112 > :octet-align=1#112 < AMR:octet-align=1;mode-set=0,2,4#112
+  AMR:mode-set=0,2,4;octet-align=1#96 < encoding-name#23 > AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 == AMR:octet-align=1;mode-set=0,2,4#112 == AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 == AMR:mode-set=0,2,4;octet-align=1#96 == AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 > AMR:mode-set=0,2,4#114 < AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 > AMR:mode-set=0,2,4;octet-align=0#97 < AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 == AMR:octet-align=1#98 == AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 < AMR-WB/16000#96 > AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 < GSM#3 > AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 > /0#0 < AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 > :octet-align=1#112 < AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4;octet-align=1#96 > :octet-align=1#112 < AMR:mode-set=0,2,4;octet-align=1#96
+  AMR:mode-set=0,2,4#114 < encoding-name#23 > AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 < AMR:octet-align=1;mode-set=0,2,4#112 > AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 < AMR:mode-set=0,2,4;octet-align=1#96 > AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 == AMR:mode-set=0,2,4#114 == AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 == AMR:mode-set=0,2,4;octet-align=0#97 == AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 < AMR:octet-align=1#98 > AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 < AMR-WB/16000#96 > AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 < GSM#3 > AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 > /0#0 < AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 > :octet-align=1#112 < AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4#114 > :octet-align=1#112 < AMR:mode-set=0,2,4#114
+  AMR:mode-set=0,2,4;octet-align=0#97 < encoding-name#23 > AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 < AMR:octet-align=1;mode-set=0,2,4#112 > AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 < AMR:mode-set=0,2,4;octet-align=1#96 > AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 == AMR:mode-set=0,2,4#114 == AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 == AMR:mode-set=0,2,4;octet-align=0#97 == AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 < AMR:octet-align=1#98 > AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 < AMR-WB/16000#96 > AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 < GSM#3 > AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 > /0#0 < AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 > :octet-align=1#112 < AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:mode-set=0,2,4;octet-align=0#97 > :octet-align=1#112 < AMR:mode-set=0,2,4;octet-align=0#97
+  AMR:octet-align=1#98 < encoding-name#23 > AMR:octet-align=1#98
+  AMR:octet-align=1#98 == AMR:octet-align=1;mode-set=0,2,4#112 == AMR:octet-align=1#98
+  AMR:octet-align=1#98 == AMR:mode-set=0,2,4;octet-align=1#96 == AMR:octet-align=1#98
+  AMR:octet-align=1#98 > AMR:mode-set=0,2,4#114 < AMR:octet-align=1#98
+  AMR:octet-align=1#98 > AMR:mode-set=0,2,4;octet-align=0#97 < AMR:octet-align=1#98
+  AMR:octet-align=1#98 == AMR:octet-align=1#98 == AMR:octet-align=1#98
+  AMR:octet-align=1#98 < AMR-WB/16000#96 > AMR:octet-align=1#98
+  AMR:octet-align=1#98 < GSM#3 > AMR:octet-align=1#98
+  AMR:octet-align=1#98 > /0#0 < AMR:octet-align=1#98
+  AMR:octet-align=1#98 > :octet-align=1#112 < AMR:octet-align=1#98
+  AMR:octet-align=1#98 > :octet-align=1#112 < AMR:octet-align=1#98
+  AMR-WB/16000#96 < encoding-name#23 > AMR-WB/16000#96
+  AMR-WB/16000#96 > AMR:octet-align=1;mode-set=0,2,4#112 < AMR-WB/16000#96
+  AMR-WB/16000#96 > AMR:mode-set=0,2,4;octet-align=1#96 < AMR-WB/16000#96
+  AMR-WB/16000#96 > AMR:mode-set=0,2,4#114 < AMR-WB/16000#96
+  AMR-WB/16000#96 > AMR:mode-set=0,2,4;octet-align=0#97 < AMR-WB/16000#96
+  AMR-WB/16000#96 > AMR:octet-align=1#98 < AMR-WB/16000#96
+  AMR-WB/16000#96 == AMR-WB/16000#96 == AMR-WB/16000#96
+  AMR-WB/16000#96 < GSM#3 > AMR-WB/16000#96
+  AMR-WB/16000#96 > /0#0 < AMR-WB/16000#96
+  AMR-WB/16000#96 > :octet-align=1#112 < AMR-WB/16000#96
+  AMR-WB/16000#96 > :octet-align=1#112 < AMR-WB/16000#96
+  GSM#3 < encoding-name#23 > GSM#3
+  GSM#3 > AMR:octet-align=1;mode-set=0,2,4#112 < GSM#3
+  GSM#3 > AMR:mode-set=0,2,4;octet-align=1#96 < GSM#3
+  GSM#3 > AMR:mode-set=0,2,4#114 < GSM#3
+  GSM#3 > AMR:mode-set=0,2,4;octet-align=0#97 < GSM#3
+  GSM#3 > AMR:octet-align=1#98 < GSM#3
+  GSM#3 > AMR-WB/16000#96 < GSM#3
+  GSM#3 == GSM#3 == GSM#3
+  GSM#3 > /0#0 < GSM#3
+  GSM#3 > :octet-align=1#112 < GSM#3
+  GSM#3 > :octet-align=1#112 < GSM#3
+  /0#0 < encoding-name#23 > /0#0
+  /0#0 < AMR:octet-align=1;mode-set=0,2,4#112 > /0#0
+  /0#0 < AMR:mode-set=0,2,4;octet-align=1#96 > /0#0
+  /0#0 < AMR:mode-set=0,2,4#114 > /0#0
+  /0#0 < AMR:mode-set=0,2,4;octet-align=0#97 > /0#0
+  /0#0 < AMR:octet-align=1#98 > /0#0
+  /0#0 < AMR-WB/16000#96 > /0#0
+  /0#0 < GSM#3 > /0#0
+  /0#0 == /0#0 == /0#0
+  /0#0 < :octet-align=1#112 > /0#0
+  /0#0 < :octet-align=1#112 > /0#0
+  :octet-align=1#112 < encoding-name#23 > :octet-align=1#112
+  :octet-align=1#112 < AMR:octet-align=1;mode-set=0,2,4#112 > :octet-align=1#112
+  :octet-align=1#112 < AMR:mode-set=0,2,4;octet-align=1#96 > :octet-align=1#112
+  :octet-align=1#112 < AMR:mode-set=0,2,4#114 > :octet-align=1#112
+  :octet-align=1#112 < AMR:mode-set=0,2,4;octet-align=0#97 > :octet-align=1#112
+  :octet-align=1#112 < AMR:octet-align=1#98 > :octet-align=1#112
+  :octet-align=1#112 < AMR-WB/16000#96 > :octet-align=1#112
+  :octet-align=1#112 < GSM#3 > :octet-align=1#112
+  :octet-align=1#112 > /0#0 < :octet-align=1#112
+  :octet-align=1#112 == :octet-align=1#112 == :octet-align=1#112
+  :octet-align=1#112 == :octet-align=1#112 == :octet-align=1#112
+  :octet-align=1#112 < encoding-name#23 > :octet-align=1#112
+  :octet-align=1#112 < AMR:octet-align=1;mode-set=0,2,4#112 > :octet-align=1#112
+  :octet-align=1#112 < AMR:mode-set=0,2,4;octet-align=1#96 > :octet-align=1#112
+  :octet-align=1#112 < AMR:mode-set=0,2,4#114 > :octet-align=1#112
+  :octet-align=1#112 < AMR:mode-set=0,2,4;octet-align=0#97 > :octet-align=1#112
+  :octet-align=1#112 < AMR:octet-align=1#98 > :octet-align=1#112
+  :octet-align=1#112 < AMR-WB/16000#96 > :octet-align=1#112
+  :octet-align=1#112 < GSM#3 > :octet-align=1#112
+  :octet-align=1#112 > /0#0 < :octet-align=1#112
+  :octet-align=1#112 == :octet-align=1#112 == :octet-align=1#112
+  :octet-align=1#112 == :octet-align=1#112 == :octet-align=1#112
+
+- osmo_sdp_codec_from_str():
+  osmo_sdp_codec_from_str('encoding-name#23') rc=0 res=encoding-name#23
+  osmo_sdp_codec_from_str('AMR:octet-align=1;mode-set=0,2,4#112') rc=0 res=AMR:octet-align=1;mode-set=0,2,4#112
+  osmo_sdp_codec_from_str('AMR:mode-set=0,2,4;octet-align=1#96') rc=0 res=AMR:mode-set=0,2,4;octet-align=1#96
+  osmo_sdp_codec_from_str('AMR:mode-set=0,2,4#114') rc=0 res=AMR:mode-set=0,2,4#114
+  osmo_sdp_codec_from_str('AMR:mode-set=0,2,4;octet-align=0#97') rc=0 res=AMR:mode-set=0,2,4;octet-align=0#97
+  osmo_sdp_codec_from_str('AMR:octet-align=1#98') rc=0 res=AMR:octet-align=1#98
+  osmo_sdp_codec_from_str('AMR-WB/16000#96') rc=0 res=AMR-WB/16000#96
+  osmo_sdp_codec_from_str('GSM#3') rc=0 res=GSM#3
+  osmo_sdp_codec_from_str('/0#0') rc=0 res=/0#0
+  osmo_sdp_codec_from_str(':octet-align=1#112') rc=0 res=:octet-align=1#112
+  osmo_sdp_codec_from_str(':octet-align=1#112') rc=0 res=:octet-align=1#112
+
+
+--- test_codec_list()
+osmo_sdp_codec_list_first() = NULL
+list_ctx
+ |  2 test_codec_list
+ |   1 struct osmo_sdp_codec_list
+[0] osmo_sdp_codec_list_add(AMR:octet-align=1;mode-set=0,2,4#112)
+[1] osmo_sdp_codec_list_add(GSM#3)
+[2] osmo_sdp_codec_list_add(GSM-HR-08#111)
+codec_list[0] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[1] = GSM#3
+codec_list[2] = GSM-HR-08#111
+osmo_sdp_codec_list_first() = AMR:octet-align=1;mode-set=0,2,4#112
+list_ctx
+ |  9 test_codec_list
+ |   8 struct osmo_sdp_codec_list
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    2 struct osmo_sdp_codec
+ |     1 GSM
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+osmo_sdp_codec_list_to_str_c(summarize=true):
+ 'AMR#112 GSM#3 GSM-HR-08#111'
+osmo_sdp_codec_list_to_str_c(summarize=false):
+ 'AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111'
+
+- add same entries again with once=exact, nothing should change
+[] osmo_sdp_codec_list_add(AMR:octet-align=1;mode-set=0,2,4#112)
+[] osmo_sdp_codec_list_add(GSM#3)
+[] osmo_sdp_codec_list_add(GSM-HR-08#111)
+codec_list[0] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[1] = GSM#3
+codec_list[2] = GSM-HR-08#111
+list_ctx
+ |  9 test_codec_list
+ |   8 struct osmo_sdp_codec_list
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    2 struct osmo_sdp_codec
+ |     1 GSM
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+osmo_sdp_codec_list_to_str_c(summarize=true):
+ 'AMR#112 GSM#3 GSM-HR-08#111'
+osmo_sdp_codec_list_to_str_c(summarize=false):
+ 'AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111'
+
+- add same entries again with once=NULL, duplicates are added
+[] osmo_sdp_codec_list_add(AMR:octet-align=1;mode-set=0,2,4#112)
+[] osmo_sdp_codec_list_add(GSM#3)
+[] osmo_sdp_codec_list_add(GSM-HR-08#111)
+codec_list[0] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[1] = GSM#3
+codec_list[2] = GSM-HR-08#111
+codec_list[3] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[4] = GSM#3
+codec_list[5] = GSM-HR-08#111
+list_ctx
+ | 16 test_codec_list
+ |  15 struct osmo_sdp_codec_list
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    2 struct osmo_sdp_codec
+ |     1 GSM
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    2 struct osmo_sdp_codec
+ |     1 GSM
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+osmo_sdp_codec_list_to_str_c(summarize=true):
+ '2*AMR#112 2*GSM#3 2*GSM-HR-08#111'
+osmo_sdp_codec_list_to_str_c(summarize=false):
+ 'AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111 AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111'
+
+- add same entries again with once=NULL,pick_unused_pt_nr=true, duplicates are added with new #nr
+[] osmo_sdp_codec_list_add(AMR:octet-align=1;mode-set=0,2,4#96)
+[] osmo_sdp_codec_list_add(GSM#97)
+[] osmo_sdp_codec_list_add(GSM-HR-08#98)
+codec_list[0] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[1] = GSM#3
+codec_list[2] = GSM-HR-08#111
+codec_list[3] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[4] = GSM#3
+codec_list[5] = GSM-HR-08#111
+codec_list[6] = AMR:octet-align=1;mode-set=0,2,4#96
+codec_list[7] = GSM#97
+codec_list[8] = GSM-HR-08#98
+list_ctx
+ | 23 test_codec_list
+ |  22 struct osmo_sdp_codec_list
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    2 struct osmo_sdp_codec
+ |     1 GSM
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    2 struct osmo_sdp_codec
+ |     1 GSM
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    2 struct osmo_sdp_codec
+ |     1 GSM
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+osmo_sdp_codec_list_to_str_c(summarize=true):
+ '3*AMR 3*GSM 3*GSM-HR-08'
+osmo_sdp_codec_list_to_str_c(summarize=false):
+ 'AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111 AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111 AMR:octet-align=1;mode-set=0,2,4#96 GSM#97 GSM-HR-08#98'
+
+- remove all 'GSM#3' entries, with osmo_sdp_codec_cmp_exact
+  osmo_sdp_codec_list_remove() = 2
+codec_list[0] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[1] = GSM-HR-08#111
+codec_list[2] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[3] = GSM-HR-08#111
+codec_list[4] = AMR:octet-align=1;mode-set=0,2,4#96
+codec_list[5] = GSM#97
+codec_list[6] = GSM-HR-08#98
+list_ctx
+ | 19 test_codec_list
+ |  18 struct osmo_sdp_codec_list
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    2 struct osmo_sdp_codec
+ |     1 GSM
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+osmo_sdp_codec_list_to_str_c(summarize=true):
+ '3*AMR 3*GSM-HR-08 GSM#97'
+osmo_sdp_codec_list_to_str_c(summarize=false):
+ 'AMR:octet-align=1;mode-set=0,2,4#112 GSM-HR-08#111 AMR:octet-align=1;mode-set=0,2,4#112 GSM-HR-08#111 AMR:octet-align=1;mode-set=0,2,4#96 GSM#97 GSM-HR-08#98'
+- remove all 'GSM' entries, with osmo_sdp_codec_cmp_equivalent
+  osmo_sdp_codec_list_remove() = 1
+codec_list[0] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[1] = GSM-HR-08#111
+codec_list[2] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[3] = GSM-HR-08#111
+codec_list[4] = AMR:octet-align=1;mode-set=0,2,4#96
+codec_list[5] = GSM-HR-08#98
+list_ctx
+ | 17 test_codec_list
+ |  16 struct osmo_sdp_codec_list
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+osmo_sdp_codec_list_to_str_c(summarize=true):
+ '3*AMR 3*GSM-HR-08'
+osmo_sdp_codec_list_to_str_c(summarize=false):
+ 'AMR:octet-align=1;mode-set=0,2,4#112 GSM-HR-08#111 AMR:octet-align=1;mode-set=0,2,4#112 GSM-HR-08#111 AMR:octet-align=1;mode-set=0,2,4#96 GSM-HR-08#98'
+- osmo_sdp_codec_list_move_to_first('AMR:octet-align=1;mode-set=0,2,4#112', equivalent) = 3
+codec_list[0] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[1] = AMR:octet-align=1;mode-set=0,2,4#112
+codec_list[2] = AMR:octet-align=1;mode-set=0,2,4#96
+codec_list[3] = GSM-HR-08#111
+codec_list[4] = GSM-HR-08#111
+codec_list[5] = GSM-HR-08#98
+list_ctx
+ | 17 test_codec_list
+ |  16 struct osmo_sdp_codec_list
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+ |    2 struct osmo_sdp_codec
+ |     1 GSM-HR-08
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1;mode-set=0,2,4
+ |     1 AMR
+osmo_sdp_codec_list_to_str_c(summarize=true):
+ '3*AMR 3*GSM-HR-08'
+osmo_sdp_codec_list_to_str_c(summarize=false):
+ 'AMR:octet-align=1;mode-set=0,2,4#112 AMR:octet-align=1;mode-set=0,2,4#112 AMR:octet-align=1;mode-set=0,2,4#96 GSM-HR-08#111 GSM-HR-08#111 GSM-HR-08#98'
+- osmo_sdp_codec_list_free_items()
+  0 entries
+list_ctx
+ |  2 test_codec_list
+ |   1 struct osmo_sdp_codec_list
+osmo_sdp_codec_list_to_str_c(summarize=true):
+ '(no-codecs)'
+osmo_sdp_codec_list_to_str_c(summarize=false):
+ '(no-codecs)'
+
+
+--- test_codec_list_cmp()
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+  cmpf[0]: payload_type=false rate=false fmtp=0: A == B == A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A == B == A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A == B == A
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:octet-align=1;mode-set=0,2,4#96 GSM#3 GSM-HR-08#111
+  cmpf[0]: payload_type=false rate=false fmtp=0: A == B == A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A == B == A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A > B < A
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:mode-set=0,2,4;octet-align=1#112 GSM#3 GSM-HR-08#111
+  cmpf[0]: payload_type=false rate=false fmtp=0: A == B == A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A == B == A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A > B < A
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:octet-align=1;mode-set=7#112 GSM#3 GSM-HR-08#111
+  cmpf[0]: payload_type=false rate=false fmtp=0: A == B == A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A < B > A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A < B > A
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:octet-align=1#112 GSM#3 GSM-HR-08#111
+  cmpf[0]: payload_type=false rate=false fmtp=0: A == B == A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A == B == A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A > B < A
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:octet-align=0;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+  cmpf[0]: payload_type=false rate=false fmtp=0: A == B == A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A > B < A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A > B < A
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+  cmpf[0]: payload_type=false rate=false fmtp=0: A == B == A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A > B < A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A > B < A
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = GSM#3 GSM-HR-08#111 AMR:octet-align=1;mode-set=0,2,4#112
+  cmpf[0]: payload_type=false rate=false fmtp=0: A < B > A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A < B > A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A < B > A
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3
+  cmpf[0]: payload_type=false rate=false fmtp=0: A > B < A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A > B < A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A > B < A
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111 GSM-EFR#110
+  cmpf[0]: payload_type=false rate=false fmtp=0: A < B > A
+  cmpf[1]: payload_type=false rate=true fmtp=1: A < B > A
+  cmpf[2]: payload_type=true rate=true fmtp=2: A < B > A
+
+
+
+--- test_codec_list_intersection()
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR:octet-align=1;mode-set=0,2,4#96 GSM#97 GSM-HR-08#98
+osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=false)
+ = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=true)
+ = AMR:octet-align=1;mode-set=0,2,4#96 GSM#97 GSM-HR-08#98
+osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=false)
+ = AMR:octet-align=1;mode-set=0,2,4#96 GSM#97 GSM-HR-08#98
+osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=true)
+ = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = GSM-HR-08#98 AMR:octet-align=1;mode-set=0,2,4#96 GSM#97
+osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=false)
+ = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=true)
+ = AMR:octet-align=1;mode-set=0,2,4#96 GSM#97 GSM-HR-08#98
+osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=false)
+ = GSM-HR-08#98 AMR:octet-align=1;mode-set=0,2,4#96 GSM#97
+osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=true)
+ = GSM-HR-08#111 AMR:octet-align=1;mode-set=0,2,4#112 GSM#3
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = GSM-HR-08#98 GSM-EFR#110 GSM#97
+osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=false)
+ = GSM#3 GSM-HR-08#111
+osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=true)
+ = GSM#97 GSM-HR-08#98
+osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=false)
+ = GSM-HR-08#98 GSM#97
+osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=true)
+ = GSM-HR-08#111 GSM#3
+
+A = AMR:octet-align=1;mode-set=0,2,4#112 GSM#3 GSM-HR-08#111
+B = AMR-WB/16000#97 FOO#98 GSM-EFR#110
+osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=false)
+ = (no-codecs)
+osmo_sdp_codec_list_intersection(A, B, equivalent, translate_pt=true)
+ = (no-codecs)
+osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=false)
+ = (no-codecs)
+osmo_sdp_codec_list_intersection(B, A, equivalent, translate_pt=true)
+ = (no-codecs)
+
+
+
+--- test_obj_members()
+o->codec = AMR:octet-align=1#96
+ctx
+ |  6 test_obj_members
+ |   5 struct my_obj
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1
+ |     1 AMR
+ |    1 struct osmo_sdp_codec_list
+o->codec_list[0] = AMR:octet-align=1#96
+o->codec_list[1] = AMR:octet-align=1#97
+ctx
+ | 12 test_obj_members
+ |  11 struct my_obj
+ |    3 struct osmo_sdp_codec
+ |     1 octet-align=1
+ |     1 AMR
+ |    7 struct osmo_sdp_codec_list
+ |     3 struct osmo_sdp_codec
+ |      1 octet-align=1
+ |      1 AMR
+ |     3 struct osmo_sdp_codec
+ |      1 octet-align=1
+ |      1 AMR
+talloc_free(o)
+ctx
+ |  1 test_obj_members

tests/sdp/sdp_fmtp_test.c

@@ -0,0 +1,126 @@
+#include <inttypes.h>
+#include <osmocom/core/utils.h>
+#include <osmocom/core/application.h>
+#include <osmocom/core/logging.h>
+
+#include <osmocom/sdp/fmtp.h>
+
+struct get_val_test {
+	const char *fmtp_string;
+	const char *val_name;
+	bool expect_rc;
+	const char *expect_val;
+};
+
+const struct get_val_test get_val_tests[] = {
+	{
+		"foo=123;bar=success;baz=456", "foo",
+		true, "123"
+	},
+	{
+		"foo=123;bar=success;baz=456", "bar",
+		true, "success"
+	},
+	{
+		"foo=123;bar=success;baz=456", "baz",
+		true, "456"
+	},
+};
+
+void test_get_val(void)
+{
+	int i;
+	printf("\n--- %s()\n", __func__);
+
+	for (i = 0; i < ARRAY_SIZE(get_val_tests); i++) {
+		const struct get_val_test *t = &get_val_tests[i];
+		char val[128] = {};
+		bool rc = osmo_sdp_fmtp_get_val(val, sizeof(val), t->fmtp_string, t->val_name);
+		bool ok;
+		printf("osmo_sdp_fmtp_get_val('%s', '%s') rc=%s",
+		       t->fmtp_string, t->val_name,
+		       rc ? "true" : "false");
+		if (rc)
+			printf(" val='%s'", val);
+		ok = true;
+		if (rc != t->expect_rc) {
+			printf(" ERROR: expected rc=%s", t->expect_rc ? "true" : "false");
+			ok = false;
+		}
+		if (t->expect_val && strcmp(val, t->expect_val)) {
+			printf(" ERROR: expected val='%s'", t->expect_val);
+			ok = false;
+		}
+		if (ok)
+			printf(" ok");
+		printf("\n");
+	}
+	printf("\n--- %s() DONE\n", __func__);
+}
+
+struct get_int_test {
+	const char *fmtp_string;
+	const char *val_name;
+	int64_t defval;
+	int64_t expect_rc;
+};
+
+const struct get_int_test get_int_tests[] = {
+	{
+		"foo=123;bar=success;baz=456", "foo", -1,
+		123
+	},
+	{
+		"foo=123;bar=success;baz=456", "bar", -1,
+		-1
+	},
+	{
+		"foo=123;bar=success;baz=456", "baz", -1,
+		456
+	},
+};
+
+void test_get_int(void)
+{
+	int i;
+	printf("\n--- %s()\n", __func__);
+
+	for (i = 0; i < ARRAY_SIZE(get_int_tests); i++) {
+		const struct get_int_test *t = &get_int_tests[i];
+		int64_t rc = osmo_sdp_fmtp_get_int(t->fmtp_string, t->val_name, t->defval);
+		printf("osmo_sdp_fmtp_get_int('%s', '%s') rc=%"PRId64,
+		       t->fmtp_string, t->val_name, rc);
+		if (rc != t->expect_rc) {
+			printf(" ERROR: expected rc=%"PRId64, t->expect_rc);
+		}
+		else {
+			printf(" ok");
+		}
+		printf("\n");
+	}
+	printf("\n--- %s() DONE\n", __func__);
+}
+
+static const struct log_info_cat log_categories[] = {
+};
+
+const struct log_info log_info = {
+        .cat = log_categories,
+        .num_cat = ARRAY_SIZE(log_categories),
+};
+
+int main(void)
+{
+	void *ctx = talloc_named_const(NULL, 1, "sdp_fmtp_test");
+
+	osmo_init_logging2(ctx, &log_info);
+	log_set_print_filename2(osmo_stderr_target, LOG_FILENAME_NONE);
+	log_set_print_timestamp(osmo_stderr_target, 0);
+	log_set_use_color(osmo_stderr_target, 0);
+	log_set_print_category_hex(osmo_stderr_target, 0);
+	log_set_print_category(osmo_stderr_target, 1);
+
+	test_get_val();
+	test_get_int();
+	return 0;
+}

tests/sdp/sdp_fmtp_test.ok

@@ -0,0 +1,14 @@
+
+--- test_get_val()
+osmo_sdp_fmtp_get_val('foo=123;bar=success;baz=456', 'foo') rc=true val='123' ok
+osmo_sdp_fmtp_get_val('foo=123;bar=success;baz=456', 'bar') rc=true val='success' ok
+osmo_sdp_fmtp_get_val('foo=123;bar=success;baz=456', 'baz') rc=true val='456' ok
+
+--- test_get_val() DONE
+
+--- test_get_int()
+osmo_sdp_fmtp_get_int('foo=123;bar=success;baz=456', 'foo') rc=123 ok
+osmo_sdp_fmtp_get_int('foo=123;bar=success;baz=456', 'bar') rc=-1 ok
+osmo_sdp_fmtp_get_int('foo=123;bar=success;baz=456', 'baz') rc=456 ok
+
+--- test_get_int() DONE

tests/sdp/sdp_msg_test.c

@@ -0,0 +1,764 @@
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <ctype.h>
+#include <errno.h>
+
+#include <osmocom/core/utils.h>
+#include <osmocom/core/linuxlist.h>
+
+#include <osmocom/sdp/sdp_msg.h>
+
+void *test_ctx = NULL;
+
+static void report_callback(const void *ptr, int depth, int max_depth, int is_ref, void *priv)
+{
+        const char *name = talloc_get_name(ptr);
+	printf(" |%*s%3zu %s\n", depth, "", talloc_total_blocks(ptr), name);
+}
+
+/* Print a talloc report that is reproducible for test output verification. It contains no pointer addresses. */
+#define report(CTX) _report(CTX, #CTX)
+static void _report(void *ctx, const char *label)
+{
+	fflush(stdout);
+	fflush(stderr);
+	printf("%s\n", label);
+        talloc_report_depth_cb(ctx, 0, 100, report_callback, NULL);
+	fflush(stdout);
+}
+
+static void dump_sdp(const char *str, const char *prefix)
+{
+	while (str && *str) {
+		const char *line_end = str;
+		while (*line_end && *line_end != '\r' && *line_end != '\n')
+			line_end++;
+		while (*line_end == '\r' || *line_end == '\n')
+			line_end++;
+		printf("%s%s\n", prefix, osmo_escape_str(str, line_end - str));
+		str = line_end;
+	}
+}
+
+struct sdp_msg_test_data {
+	const char *sdp_input;
+	const char *expect_sdp_str;
+};
+
+static const struct sdp_msg_test_data sdp_msg_tests[] = {
+	{
+		"v=0\r\n"
+		"o=- 5628250 5628250 IN IP4 192.168.11.121\r\n"
+		"s=-\r\n"
+		"c=IN IP4 192.168.11.121\r\n"
+		"t=0 0\r\n"
+		"m=audio 10020 RTP/AVP 18 0 2 4 8 96 97 98 100 101\r\n"
+		"a=rtpmap:18 G729/8000\r\n"
+		"a=rtpmap:0 PCMU/8000\r\n"
+		"a=rtpmap:2 G726-32/8000\r\n"
+		"a=rtpmap:4 G723/8000\r\n"
+		"a=rtpmap:8 PCMA/8000\r\n"
+		"a=rtpmap:96 G726-40/8000\r\n"
+		"a=rtpmap:97 G726-24/8000\r\n"
+		"a=rtpmap:98 G726-16/8000\r\n"
+		"a=rtpmap:100 NSE/8000\r\n"
+		"a=fmtp:100 192-193\r\n"
+		"a=rtpmap:101 telephone-event/8000\r\n"
+		"a=fmtp:101 0-15\r\n"
+		"a=ptime:20\r\n"
+		"a=sendrecv\r\n"
+		,
+	},
+	{
+		"v=0\r\n"
+		"o=FooBar 1565090289 1565090290 IN IP4 192.168.11.151\r\n"
+		"s=FooBar\r\n"
+		"c=IN IP4 192.168.11.151\r\n"
+		"t=0 0\r\n"
+		"m=audio 16398 RTP/AVP 98\r\n"
+		"a=rtpmap:98 AMR/8000\r\n"
+		"a=fmtp:98 octet-align=1; mode-set=4\r\n"
+		"a=ptime:20\r\n"
+		"a=rtcp:16399 IN IP4 192.168.11.151\r\n"
+		,
+		"v=0\r\n"
+		"o=FooBar 1565090289 1565090290 IN IP4 192.168.11.151\r\n"
+		"s=FooBar\r\n"
+		"c=IN IP4 192.168.11.151\r\n"
+		"t=0 0\r\n"
+		"m=audio 16398 RTP/AVP 98\r\n"
+		"a=rtpmap:98 AMR/8000\r\n"
+		"a=fmtp:98 octet-align=1; mode-set=4\r\n"
+		"a=ptime:20\r\n"
+		/* The rtcp line is dropped, not supported yet */
+	},
+	{
+		"v=0\r\n"
+		"o=FooBar 1565090289 1565090290 IN IP4 192.168.11.151\r\n"
+		"s=FooBar\r\n"
+		"c=IN IP4 192.168.11.140\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 18 0 4 8 101\r\n"
+		"a=rtpmap:18 G729/8000\r\n"
+		"a=rtpmap:0 PCMU/8000\r\n"
+		"a=rtpmap:4 G723/8000\r\n"
+		"a=rtpmap:8 PCMA/8000\r\n"
+		"a=rtpmap:101 telephone-event/8000\r\n"
+		"a=fmtp:101 0-15\r\n"
+		"a=sendrecv\r\n"
+		"a=rtcp:30437\r\n"
+		"a=ptime:20\r\n"
+		,
+		"v=0\r\n"
+		"o=FooBar 1565090289 1565090290 IN IP4 192.168.11.151\r\n"
+		"s=FooBar\r\n"
+		"c=IN IP4 192.168.11.140\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 18 0 4 8 101\r\n"
+		"a=rtpmap:18 G729/8000\r\n"
+		"a=rtpmap:0 PCMU/8000\r\n"
+		"a=rtpmap:4 G723/8000\r\n"
+		"a=rtpmap:8 PCMA/8000\r\n"
+		"a=rtpmap:101 telephone-event/8000\r\n"
+		"a=fmtp:101 0-15\r\n"
+		/* a=sendrecv ends up further below */
+		/* The rtcp line is dropped, not supported yet */
+		"a=ptime:20\r\n"
+		"a=sendrecv\r\n"
+		,
+	},
+	{
+		"v=0\r\n"
+		"o=FooBar 1565090289 1565090290 IN IP4 192.168.11.151\r\n"
+		"s=FooBar\r\n"
+		"c=IN IP4 192.168.11.140\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 18 0 4 8 101\r\n"
+		"a=rtpmap:18 G729/8000\r\n"
+		"a=rtpmap:0 PCMU/8000\r\n"
+		"a=rtpmap:4 G723/8000\r\n"
+		"a=rtpmap:8 PCMA/8000\r\n"
+		"a=rtpmap:101 telephone-event/8000\r\n"
+		"a=fmtp:101 0-15\r\n"
+		"a=recvonly\r\n"
+		"a=rtcp:30437\r\n"
+		"a=ptime:20\r\n"
+		,
+		"v=0\r\n"
+		"o=FooBar 1565090289 1565090290 IN IP4 192.168.11.151\r\n"
+		"s=FooBar\r\n"
+		"c=IN IP4 192.168.11.140\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 18 0 4 8 101\r\n"
+		"a=rtpmap:18 G729/8000\r\n"
+		"a=rtpmap:0 PCMU/8000\r\n"
+		"a=rtpmap:4 G723/8000\r\n"
+		"a=rtpmap:8 PCMA/8000\r\n"
+		"a=rtpmap:101 telephone-event/8000\r\n"
+		"a=fmtp:101 0-15\r\n"
+		/* a=recvonly ends up further below */
+		/* The rtcp line is dropped, not supported yet */
+		"a=ptime:20\r\n"
+		"a=recvonly\r\n"
+		,
+	},
+	{
+		"v=0\r\n"
+		"o=FooBar 1565090289 1565090290 IN IP4 192.168.11.151\r\n"
+		"s=FooBar\r\n"
+		"c=IN IP4 192.168.11.140\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 18 0 4 8 101\r\n"
+		"a=rtpmap:18 G729/8000\r\n"
+		"a=rtpmap:0 PCMU/8000\r\n"
+		"a=rtpmap:4 G723/8000\r\n"
+		"a=rtpmap:8 PCMA/8000\r\n"
+		"a=rtpmap:101 telephone-event/8000\r\n"
+		"a=fmtp:101 0-15\r\n"
+		"a=ptime:20\r\n"
+		"a=sendonly\r\n"
+		,
+	},
+	{
+		"v=0\r\n"
+		"o=FooBar 1565090289 1565090290 IN IP4 192.168.11.151\r\n"
+		"s=FooBar\r\n"
+		"c=IN IP4 192.168.11.140\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 18 0 4 8 101\r\n"
+		"a=rtpmap:18 G729/8000\r\n"
+		"a=rtpmap:0 PCMU/8000\r\n"
+		"a=rtpmap:4 G723/8000\r\n"
+		"a=rtpmap:8 PCMA/8000\r\n"
+		"a=rtpmap:101 telephone-event/8000\r\n"
+		"a=fmtp:101 0-15\r\n"
+		"a=ptime:20\r\n"
+		"a=inactive\r\n"
+		,
+	},
+};
+
+static void test_parse_and_compose(void)
+{
+	void *ctx = talloc_named_const(test_ctx, 0, __func__);
+	void *print_ctx = talloc_named_const(test_ctx, 0, "print");
+	int i;
+	bool ok = true;
+
+	printf("\n\n%s\n", __func__);
+
+	for (i = 0; i < ARRAY_SIZE(sdp_msg_tests); i++) {
+		const struct sdp_msg_test_data *t = &sdp_msg_tests[i];
+		struct osmo_sdp_msg *sdp_msg;
+		char str[1024];
+		const char *expect;
+		struct osmo_sdp_err err;
+
+		printf("\n[%d]\n", i);
+		dump_sdp(t->sdp_input, "sdp input: ");
+
+		sdp_msg = osmo_sdp_msg_decode(ctx, t->sdp_input, &err);
+
+		if (err.rc) {
+			printf("ERROR: %s at %s\n", strerror(abs(err.rc)),
+			       osmo_quote_cstr_c(print_ctx, err.at_input_str, err.at_input_str_len));
+			ok = false;
+		}
+		printf("parsed SDP message %s\n", osmo_sdp_msg_to_str_c(print_ctx, sdp_msg, false));
+
+		osmo_sdp_msg_encode_buf(str, sizeof(str), sdp_msg);
+		dump_sdp(str, "osmo_sdp_msg_encode_buf: ");
+		expect = t->expect_sdp_str ? : t->sdp_input;
+		if (strcmp(str, expect)) {
+			int j;
+			ok = false;
+			printf("ERROR:\n");
+			dump_sdp(expect, "expect: ");
+			for (j = 0; expect[j]; j++) {
+				if (expect[j] != str[j]) {
+					printf("ERROR at position %d, at:\n", j);
+					dump_sdp(str + j, "     mismatch: ");
+					break;
+				}
+			}
+		} else
+			printf("[%d] ok\n", i);
+
+		report(ctx);
+		printf("talloc_free(sdp_msg)\n");
+		talloc_free(sdp_msg);
+		report(ctx);
+
+		if (talloc_total_blocks(ctx) != 1) {
+			printf("ERROR: memleak\n");
+			talloc_free_children(ctx);
+		}
+		printf("\n");
+	}
+
+	OSMO_ASSERT(ok);
+	talloc_free(ctx);
+	talloc_free(print_ctx);
+}
+
+struct intersect_test_data {
+	const char *descr;
+	const char *sdp_msg_a;
+	const char *sdp_msg_b;
+	const char *expect_intersection;
+};
+
+#define SDP_1 \
+		"v=0\r\n" \
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n" \
+		"s=GSM Call\r\n" \
+		"c=IN IP4 23.42.23.42\r\n" \
+		"t=0 0\r\n" \
+		"m=audio 30436 RTP/AVP 112 3 111 110\r\n" \
+		"a=rtpmap:112 AMR/8000\r\n" \
+		"a=fmtp:112 octet-align=1\r\n" \
+		"a=rtpmap:3 GSM/8000\r\n" \
+		"a=rtpmap:111 GSM-HR-08/8000\r\n" \
+		"a=rtpmap:110 GSM-EFR/8000\r\n" \
+		"a=ptime:20\r\n"
+
+#define SDP_2 \
+		"v=0\r\n" \
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n" \
+		"s=GSM Call\r\n" \
+		"c=IN IP4 23.42.23.42\r\n" \
+		"t=0 0\r\n" \
+		"m=audio 30436 RTP/AVP 112 110\r\n" \
+		"a=rtpmap:112 AMR/8000\r\n" \
+		"a=fmtp:112 octet-align=1\r\n" \
+		"a=rtpmap:110 GSM-EFR/8000\r\n" \
+		"a=ptime:20\r\n"
+
+#define SDP_3 \
+		"v=0\r\n" \
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n" \
+		"s=GSM Call\r\n" \
+		"c=IN IP4 23.42.23.42\r\n" \
+		"t=0 0\r\n" \
+		"m=audio 30436 RTP/AVP 3 111 123\r\n" \
+		"a=rtpmap:3 GSM/8000\r\n" \
+		"a=rtpmap:111 GSM-HR-08/8000\r\n" \
+		"a=rtpmap:123 FOO/8000\r\n" \
+		"a=ptime:20\r\n"
+
+#define SDP_4 \
+		"v=0\r\n" \
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n" \
+		"s=GSM Call\r\n" \
+		"c=IN IP4 23.42.23.42\r\n" \
+		"t=0 0\r\n" \
+		"m=audio 30436 RTP/AVP 3 111\r\n" \
+		"a=rtpmap:3 GSM/8000\r\n" \
+		"a=rtpmap:111 GSM-HR-08/8000\r\n" \
+		"a=ptime:20\r\n"
+
+#define SDP_5 \
+		"v=0\r\n" \
+		"o=libosmo-sdp 0 0 IN IP4 0.0.0.0\r\n" \
+		"s=GSM Call\r\n" \
+		"c=IN IP4 0.0.0.0\r\n" \
+		"t=0 0\r\n" \
+		"m=audio 0 RTP/AVP 112 113 110 3 111\r\n" \
+		"a=rtpmap:112 AMR/8000\r\n" \
+		"a=fmtp:112 octet-align=1;mode-set=0,1,2,3\r\n" \
+		"a=rtpmap:113 AMR-WB/8000\r\n" \
+		"a=fmtp:113 octet-align=1\r\n" \
+		"a=rtpmap:110 GSM-EFR/8000\r\n" \
+		"a=rtpmap:3 GSM/8000\r\n" \
+		"a=rtpmap:111 GSM-HR-08/8000\r\n" \
+		"a=ptime:20\r\n"
+
+static const struct intersect_test_data intersect_tests[] = {
+	{
+		"identical codecs lead to no change"
+		,
+		SDP_1
+		,
+		"c=IN IP4 5.6.7.8\r\n" \
+		"m=audio 12345 RTP/AVP 112 3 111 110\r\n"
+		"a=rtpmap:112 AMR/8000\r\n"
+		"a=fmtp:112 octet-align=1\r\n"
+		"a=rtpmap:3 GSM/8000\r\n"
+		"a=rtpmap:111 GSM-HR-08/8000\r\n"
+		"a=rtpmap:110 GSM-EFR/8000\r\n"
+		,
+		SDP_1
+	},
+	{
+		"identical codecs in different order also lead to no change"
+		,
+		SDP_1
+		,
+		"c=IN IP4 5.6.7.8\r\n" \
+		"m=audio 12345 RTP/AVP 3 110 111 112\r\n"
+		"a=rtpmap:3 GSM/8000\r\n"
+		"a=rtpmap:110 GSM-EFR/8000\r\n"
+		"a=rtpmap:111 GSM-HR-08/8000\r\n"
+		"a=rtpmap:112 AMR/8000\r\n"
+		"a=fmtp:112 octet-align=1\r\n"
+		,
+		SDP_1
+	},
+	{
+		"identical codecs with mismatching payload type numbers also lead to no change"
+		,
+		SDP_1
+		,
+		"c=IN IP4 5.6.7.8\r\n" \
+		"m=audio 12345 RTP/AVP 96 97 98 99\r\n"
+		"a=rtpmap:96 GSM/8000\r\n"
+		"a=rtpmap:97 GSM-EFR/8000\r\n"
+		"a=rtpmap:98 GSM-HR-08/8000\r\n"
+		"a=rtpmap:99 AMR/8000\r\n"
+		"a=fmtp:99 octet-align=1\r\n"
+		,
+		SDP_1
+	},
+	{
+		"identical codecs plus some extra codecs also lead to no change"
+		,
+		SDP_1
+		,
+		"c=IN IP4 5.6.7.8\r\n" \
+		"m=audio 12345 RTP/AVP 8 0 96 97 98 99\r\n"
+		"a=rtpmap:8 PCMA/8000\r\n"
+		"a=rtpmap:0 PCMU/8000\r\n"
+		"a=rtpmap:96 GSM/8000\r\n"
+		"a=rtpmap:97 GSM-EFR/8000\r\n"
+		"a=rtpmap:98 GSM-HR-08/8000\r\n"
+		"a=rtpmap:99 AMR/8000\r\n"
+		"a=fmtp:99 octet-align=1\r\n"
+		,
+		SDP_1
+	},
+	{
+		"some codecs removed",
+		SDP_1,
+		SDP_2,
+		SDP_2,
+	},
+	{
+		"other codecs removed",
+		SDP_1,
+		SDP_3,
+		SDP_4,
+	},
+	{
+		"all codecs removed",
+		SDP_1
+		,
+		"s=empty"
+		,
+		"v=0\r\n" \
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n" \
+		"s=GSM Call\r\n" \
+		"c=IN IP4 23.42.23.42\r\n" \
+		"t=0 0\r\n" \
+		"m=audio 30436 RTP/AVP\r\n" \
+		"a=ptime:20\r\n"
+	},
+	{
+		"some real world test case",
+		SDP_5, SDP_5, SDP_5,
+	},
+};
+
+static const char *sdp_msg_logstr(const struct osmo_sdp_msg *sdp_msg)
+{
+	static char buf[1024];
+	osmo_sdp_msg_encode_buf(buf, sizeof(buf), sdp_msg);
+	return buf;
+}
+
+static void test_intersect(void)
+{
+	int i;
+	bool ok = true;
+	void *ctx = talloc_named_const(test_ctx, 0, __func__);
+
+	printf("\n\n%s\n", __func__);
+
+	for (i = 0; i < ARRAY_SIZE(intersect_tests); i++) {
+		const struct intersect_test_data *t = &intersect_tests[i];
+		struct osmo_sdp_msg *sdp_msg_a = NULL;
+		struct osmo_sdp_msg *sdp_msg_b = NULL;
+		char str[1024];
+		printf("\n[%d] %s\n", i, t->descr);
+		dump_sdp(t->sdp_msg_a, "SDP A: ");
+		dump_sdp(t->sdp_msg_b, " SDP B: ");
+
+		sdp_msg_a = osmo_sdp_msg_decode(ctx, t->sdp_msg_a, NULL);
+		if (!sdp_msg_a) {
+			printf("ERROR parsing SDP A\n");
+			break;
+		}
+		dump_sdp(sdp_msg_logstr(sdp_msg_a), "parsed SDP A: ");
+
+		sdp_msg_b = osmo_sdp_msg_decode(ctx, t->sdp_msg_b, NULL);
+		if (!sdp_msg_b) {
+			printf("ERROR parsing SDP B\n");
+			break;
+		}
+		dump_sdp(sdp_msg_logstr(sdp_msg_b), "parsed SDP B: ");
+
+		osmo_sdp_codec_list_intersection(sdp_msg_a->codecs, sdp_msg_b->codecs,
+						 &osmo_sdp_codec_cmp_equivalent,
+						 false);
+		osmo_sdp_msg_encode_buf(str, sizeof(str), sdp_msg_a);
+		dump_sdp(str, "intersection(a,b): ");
+		if (strcmp(str, t->expect_intersection)) {
+			int j;
+			ok = false;
+			printf("ERROR:\n");
+			dump_sdp(t->expect_intersection, "expect_intersection: ");
+			for (j = 0; t->expect_intersection[j]; j++) {
+				if (t->expect_intersection[j] != str[j]) {
+					printf("ERROR at position %d, at:\n", j);
+					dump_sdp(str + j, "     mismatch: ");
+					break;
+				}
+			}
+		} else
+			printf("[%d] ok\n", i);
+
+		report(ctx);
+		printf("talloc_free(sdp_msg_a)\n");
+		talloc_free(sdp_msg_a);
+		report(ctx);
+		printf("talloc_free(sdp_msg_b)\n");
+		talloc_free(sdp_msg_b);
+		report(ctx);
+
+		if (talloc_total_blocks(ctx) != 1) {
+			printf("ERROR: memleak\n");
+			talloc_free_children(ctx);
+		}
+		printf("\n");
+	}
+
+	OSMO_ASSERT(ok);
+	talloc_free(ctx);
+}
+
+struct sdp_select_test_data {
+	const char *sdp;
+	const struct osmo_sdp_codec_cmp_flags *cmpf;
+	const struct osmo_sdp_codec select;
+	const char *expect_sdp;
+};
+
+static const struct osmo_sdp_codec_cmp_flags pt_only = { .payload_type = true };
+
+static const struct sdp_select_test_data sdp_select_tests[] = {
+	{
+		"v=0\r\n"
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n"
+		"s=GSM Call\r\n"
+		"c=IN IP4 23.42.23.42\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 112 3 111 110\r\n"
+		"a=rtpmap:112 AMR/8000\r\n"
+		"a=fmtp:112 octet-align=1\r\n"
+		"a=rtpmap:3 GSM/8000\r\n"
+		"a=rtpmap:111 GSM-HR-08/8000\r\n"
+		"a=rtpmap:110 GSM-EFR/8000\r\n"
+		"a=ptime:20\r\n"
+		,
+		&pt_only,
+		{ .payload_type = 112, },
+		NULL
+	},
+	{
+		"v=0\r\n"
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n"
+		"s=GSM Call\r\n"
+		"c=IN IP4 23.42.23.42\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 112 3 111 110\r\n"
+		"a=rtpmap:112 AMR/8000\r\n"
+		"a=fmtp:112 octet-align=1\r\n"
+		"a=rtpmap:3 GSM/8000\r\n"
+		"a=rtpmap:111 GSM-HR-08/8000\r\n"
+		"a=rtpmap:110 GSM-EFR/8000\r\n"
+		"a=ptime:20\r\n"
+		,
+		&pt_only,
+		{ .payload_type = 3, },
+		"v=0\r\n"
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n"
+		"s=GSM Call\r\n"
+		"c=IN IP4 23.42.23.42\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 3 112 111 110\r\n"
+		"a=rtpmap:3 GSM/8000\r\n"
+		"a=rtpmap:112 AMR/8000\r\n"
+		"a=fmtp:112 octet-align=1\r\n"
+		"a=rtpmap:111 GSM-HR-08/8000\r\n"
+		"a=rtpmap:110 GSM-EFR/8000\r\n"
+		"a=ptime:20\r\n"
+	},
+	{
+		"v=0\r\n"
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n"
+		"s=GSM Call\r\n"
+		"c=IN IP4 23.42.23.42\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 112 3 111 110\r\n"
+		"a=rtpmap:112 AMR/8000\r\n"
+		"a=fmtp:112 octet-align=1\r\n"
+		"a=rtpmap:3 GSM/8000\r\n"
+		"a=rtpmap:111 GSM-HR-08/8000\r\n"
+		"a=rtpmap:110 GSM-EFR/8000\r\n"
+		"a=ptime:20\r\n"
+		,
+		&pt_only,
+		{ .payload_type = 111, },
+		"v=0\r\n"
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n"
+		"s=GSM Call\r\n"
+		"c=IN IP4 23.42.23.42\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 111 112 3 110\r\n"
+		"a=rtpmap:111 GSM-HR-08/8000\r\n"
+		"a=rtpmap:112 AMR/8000\r\n"
+		"a=fmtp:112 octet-align=1\r\n"
+		"a=rtpmap:3 GSM/8000\r\n"
+		"a=rtpmap:110 GSM-EFR/8000\r\n"
+		"a=ptime:20\r\n"
+	},
+	{
+		"v=0\r\n"
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n"
+		"s=GSM Call\r\n"
+		"c=IN IP4 23.42.23.42\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 112 3 111 110\r\n"
+		"a=rtpmap:112 AMR/8000\r\n"
+		"a=fmtp:112 octet-align=1\r\n"
+		"a=rtpmap:3 GSM/8000\r\n"
+		"a=rtpmap:111 GSM-HR-08/8000\r\n"
+		"a=rtpmap:110 GSM-EFR/8000\r\n"
+		"a=ptime:20\r\n"
+		,
+		&pt_only,
+		{ .payload_type = 110, },
+		"v=0\r\n"
+		"o=libosmo-sdp 0 0 IN IP4 23.42.23.42\r\n"
+		"s=GSM Call\r\n"
+		"c=IN IP4 23.42.23.42\r\n"
+		"t=0 0\r\n"
+		"m=audio 30436 RTP/AVP 110 112 3 111\r\n"
+		"a=rtpmap:110 GSM-EFR/8000\r\n"
+		"a=rtpmap:112 AMR/8000\r\n"
+		"a=fmtp:112 octet-align=1\r\n"
+		"a=rtpmap:3 GSM/8000\r\n"
+		"a=rtpmap:111 GSM-HR-08/8000\r\n"
+		"a=ptime:20\r\n"
+	},
+
+};
+
+static void test_select(void)
+{
+	int i;
+	bool ok = true;
+	void *ctx = talloc_named_const(test_ctx, 0, __func__);
+	void *print_ctx = talloc_named_const(test_ctx, 0, "print");
+
+	printf("\n\n%s\n", __func__);
+
+	for (i = 0; i < ARRAY_SIZE(sdp_select_tests); i++) {
+		const struct sdp_select_test_data *t = &sdp_select_tests[i];
+		struct osmo_sdp_msg *sdp_msg;
+		char buf[1024];
+		const char *expect_sdp;
+
+		printf("\n[%d]\n", i);
+		sdp_msg = osmo_sdp_msg_decode(ctx, t->sdp, NULL);
+		if (!sdp_msg) {
+			printf("ERROR parsing SDP\n");
+			break;
+		}
+		printf("SDP: %s\n", osmo_sdp_codec_list_to_str_c(print_ctx, sdp_msg->codecs, false));
+
+		printf("Select: %s\n", osmo_sdp_codec_to_str_c(print_ctx, &t->select));
+		osmo_sdp_codec_list_move_to_first(sdp_msg->codecs, &t->select, t->cmpf);
+
+		printf("SDP: %s\n", osmo_sdp_codec_list_to_str_c(print_ctx, sdp_msg->codecs, false));
+		osmo_sdp_msg_encode_buf(buf, sizeof(buf), sdp_msg);
+
+		expect_sdp = t->expect_sdp ? : t->sdp;
+		if (strcmp(buf, expect_sdp)) {
+			int j;
+			ok = false;
+			printf("ERROR:\n");
+			dump_sdp(buf, "selection result: ");
+			dump_sdp(expect_sdp, "expect result: ");
+			for (j = 0; expect_sdp[j]; j++) {
+				if (expect_sdp[j] != buf[j]) {
+					printf("ERROR at position %d, at:\n", j);
+					dump_sdp(buf + j, "     mismatch: ");
+					break;
+				}
+			}
+		} else
+			printf("[%d] ok\n", i);
+
+		report(ctx);
+		printf("talloc_free(sdp_msg)\n");
+		talloc_free(sdp_msg);
+		report(ctx);
+		if (talloc_total_blocks(ctx) != 1) {
+			printf("ERROR: memleak\n");
+			talloc_free_children(ctx);
+		}
+		printf("\n");
+		talloc_free_children(print_ctx);
+	}
+
+	OSMO_ASSERT(ok);
+	talloc_free(ctx);
+	talloc_free(print_ctx);
+}
+
+
+struct my_obj {
+	struct osmo_sdp_msg *sdp_msg;
+};
+
+static struct my_obj *my_obj_alloc(void *ctx)
+{
+	struct my_obj *o = talloc_zero(ctx, struct my_obj);
+	return o;
+}
+
+static void test_obj_members(void)
+{
+	void *ctx = talloc_named_const(test_ctx, 0, __func__);
+	void *print_ctx = talloc_named_const(test_ctx, 0, "print");
+	int i;
+
+	struct my_obj *o;
+
+	printf("\n\n--- %s()\n", __func__);
+	o = my_obj_alloc(ctx);
+
+	o->sdp_msg = osmo_sdp_msg_alloc(o);
+
+	printf("o->sdp_msg = '%s'\n", osmo_sdp_msg_encode_c(print_ctx, o->sdp_msg));
+	report(ctx);
+
+	const struct osmo_sdp_codec all_codecs[] = {
+		{ .payload_type = 112, .encoding_name = "AMR", .rate = 8000, .fmtp = "octet-align=1;mode-set=0,2,4" },
+		{ .payload_type = 3, .encoding_name = "GSM", .rate = 8000 },
+		{ .payload_type = 111, .encoding_name = "GSM-HR-08", .rate = 8000 },
+	};
+
+	for (i = 0; i < ARRAY_SIZE(all_codecs); i++)
+		osmo_sdp_codec_list_add(o->sdp_msg->codecs, &all_codecs[i], false, false);
+
+	printf("o->sdp_msg = '%s'\n", osmo_sdp_msg_encode_c(print_ctx, o->sdp_msg));
+
+	report(ctx);
+	printf("talloc_free(o)\n");
+	talloc_free(o);
+	report(ctx);
+	talloc_free(ctx);
+	talloc_free(print_ctx);
+}
+
+typedef void (*test_func_t)(void);
+
+static const test_func_t test_func[] = {
+	test_parse_and_compose,
+	test_intersect,
+	test_select,
+	test_obj_members,
+};
+
+int main(void)
+{
+	int i;
+	test_ctx = talloc_named_const(NULL, 0, "sdp_codec_test");
+
+	for (i = 0; i < ARRAY_SIZE(test_func); i++) {
+
+		test_func[i]();
+
+		if (talloc_total_blocks(test_ctx) != 1) {
+			talloc_report_full(test_ctx, stderr);
+			printf("ERROR after test %d: memory leak\n", i);
+			return -1;
+		}
+	}
+
+	talloc_free(test_ctx);
+	return 0;
+}

tests/testsuite.at

@@ -13,3 +13,24 @@ AT_KEYWORDS([mgcp])
 cat $abs_srcdir/mgcp/mgcp_test.ok > expout
 AT_CHECK([$abs_top_builddir/tests/mgcp/mgcp_test], [], [expout], [ignore])
 AT_CLEANUP
+
+AT_SETUP([sdp_fmtp])
+AT_KEYWORDS([sdp_fmtp])
+cat $abs_srcdir/sdp/sdp_fmtp_test.ok > expout
+cat $abs_srcdir/sdp/sdp_fmtp_test.err > experr
+AT_CHECK([$abs_top_builddir/tests/sdp/sdp_fmtp_test], [], [expout], [experr])
+AT_CLEANUP
+
+AT_SETUP([sdp_codec])
+AT_KEYWORDS([sdp_codec])
+cat $abs_srcdir/sdp/sdp_codec_test.ok > expout
+cat $abs_srcdir/sdp/sdp_codec_test.err > experr
+AT_CHECK([$abs_top_builddir/tests/sdp/sdp_codec_test], [], [expout], [experr])
+AT_CLEANUP
+
+AT_SETUP([sdp_msg])
+AT_KEYWORDS([sdp_msg])
+cat $abs_srcdir/sdp/sdp_msg_test.ok > expout
+cat $abs_srcdir/sdp/sdp_msg_test.err > experr
+AT_CHECK([$abs_top_builddir/tests/sdp/sdp_msg_test], [], [expout], [experr])
+AT_CLEANUP