libosmo-pfcp: implement PFCP header and msg handling

Related: SYS#5599
Change-Id: I3f85ea052a6b7c064244a8093777e53a47c8c61e

include/osmocom/pfcp/Makefile.am

@@ -1,6 +1,7 @@
 pfcp_HEADERS = \
 	pfcp_ies_custom.h \
 	pfcp_ies_auto.h \
+	pfcp_msg.h \
 	pfcp_proto.h \
 	pfcp_strs.h \
 	$(NULL)

include/osmocom/pfcp/pfcp_msg.h

@@ -0,0 +1,197 @@
+/* PFCP message encoding and decoding */
+/*
+ * (C) 2021-2022 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 <stdint.h>
+#include <stdbool.h>
+#include <inttypes.h>
+
+#include <osmocom/core/socket.h>
+#include <osmocom/core/msgb.h>
+#include <osmocom/core/fsm.h>
+
+#include <osmocom/pfcp/pfcp_proto.h>
+#include <osmocom/pfcp/pfcp_ies_auto.h>
+#include <osmocom/pfcp/pfcp_strs.h>
+
+struct msgb;
+struct osmo_t16l16v_ie;
+struct osmo_pfcp_msg;
+
+#define OSMO_PFCP_MSGB_ALLOC_SIZE 2048
+
+#define OSMO_LOG_PFCP_MSG_SRC(M, LEVEL, file, line, FMT, ARGS...) do { \
+		struct osmo_fsm_inst *_fi = (M) ? ((M)->ctx.session_fi ?: (M)->ctx.peer_fi) : NULL; \
+		enum osmo_pfcp_cause *cause = osmo_pfcp_msg_cause(M); \
+		if ((M)->h.seid_present) { \
+			LOGPFSMSLSRC(_fi, DLPFCP, LEVEL, file, line, \
+				     "%s%s PFCP seq-%u SEID-0x%"PRIx64" %s%s%s: " FMT, \
+				     _fi ? "" : osmo_sockaddr_to_str_c(OTC_SELECT, &(M)->remote_addr), \
+				     (M)->rx ? "-rx->" : "<-tx-", (M)->h.sequence_nr, \
+				     (M)->h.seid, \
+				     osmo_pfcp_message_type_str((M)->h.message_type), cause ? ": " : "", \
+				     cause ? osmo_pfcp_cause_str(*cause) : "", ##ARGS); \
+		} else { \
+			LOGPFSMSLSRC(_fi, DLPFCP, LEVEL, file, line, \
+				     "%s%s PFCP seq-%u %s%s%s: " FMT, \
+				     _fi ? "" : osmo_sockaddr_to_str_c(OTC_SELECT, &(M)->remote_addr), \
+				     (M)->rx ? "-rx->" : "<-tx-", (M)->h.sequence_nr, \
+				     osmo_pfcp_message_type_str((M)->h.message_type), cause ? ": " : "", \
+				     cause ? osmo_pfcp_cause_str(*cause) : "", ##ARGS); \
+		} \
+	} while (0)
+
+#define OSMO_LOG_PFCP_MSG(M, LEVEL, FMT, ARGS...) \
+	OSMO_LOG_PFCP_MSG_SRC(M, LEVEL, __FILE__, __LINE__, FMT, ##ARGS)
+
+struct osmo_pfcp_header_parsed {
+	uint8_t version;
+	enum osmo_pfcp_message_type message_type;
+	uint32_t sequence_nr;
+	bool priority_present;
+	uint8_t priority;
+	bool seid_present;
+	uint64_t seid;
+};
+
+/* For PFCP requests, notify when a PFCP response has arrived, or when the PFCP response timed out.
+ * When rx_resp == NULL, receiving a response timed out or the response could not be decoded.
+ * On error, errmsg may convey a human readable error message.
+ * Return 1 to also pass rx_resp to osmo_pfcp_endpoint->rx_msg(), return 0 to mark rx_resp handled and not pass it to
+ * rx_msg() (to save lookup iterations). Return negative on error, rx_resp is dropped.
+ * Find in req the original osmo_pfcp_msg instance; in req->ctx.priv, arbitrary user data may be passed.
+ * For example:
+ *
+ *  static int on_foo_resp(struct osmo_pfcp_msg *req, struct osmo_pfcp_msg *rx_resp, const char *errmsg)
+ *  {
+ *          struct something *obj = req->ctx.priv;
+ *          if (!rx_resp) {
+ *                  handle_error();
+ *                  return 0;
+ *          }
+ *          handle_response(obj, rx_resp);
+ *          return 0;
+ *  }
+ *
+ *  int do_request(struct something *obj)
+ *  {
+ *          struct osmo_pfcp_msg *req;
+ *          req = osmo_pfcp_msg_alloc_tx(pfcp_ep, &upf_addr, &pfcp_ep->cfg.local_node_id, NULL, OSMO_PFCP_MSGT_FOO);
+ *          req->h.seid_present = true;
+ *          req->h.seid = remote_seid;
+ *          req->ies.foo... = ...;
+ *          req->ctx.on_resp = on_foo_resp;
+ *          req->ctx.priv = obj;
+ *          return osmo_pfcp_endpoint_tx(pfcp_ep, req);
+ *  }
+ */
+typedef int (*osmo_pfcp_resp_cb)(struct osmo_pfcp_msg *req, struct osmo_pfcp_msg *rx_resp, const char *errmsg);
+
+struct osmo_pfcp_msg {
+	/* Peer's remote address. Received from this peer, or should be sent to this peer. */
+	struct osmo_sockaddr remote_addr;
+	/* True when this message was received from a remote; false when this message is going to be sent. */
+	bool rx;
+	/* True when this message is a Response message type; false if Request. This is set by
+	 * osmo_pfcp_msg_decode() for received messages, and by osmo_pfcp_msg_alloc_tx */
+	bool is_response;
+
+	struct osmo_pfcp_header_parsed h;
+
+	int ofs_cause;
+	int ofs_node_id;
+
+	/* The union of decoded IEs from all supported PFCP message types.  The union and its structure is defined in
+	 * pfcp_ies_auto.h, which is generated by gen__pfcp_ies_auto.c.
+	 */
+	union osmo_pfcp_ies ies;
+
+	/* Context information about this message, used for logging */
+	struct {
+		/* Peer FSM instance that this message is received from / sent to. This can be set in the
+		 * osmo_pfcp_endpoint->set_msg_ctx() implementation, up to the caller. If present, this is used for
+		 * logging context, and can also be used by the caller to reduce lookup iterations. */
+		struct osmo_fsm_inst *peer_fi;
+		struct osmo_use_count *peer_use_count;
+		const char *peer_use_token;
+
+		/* Session FSM instance that this message is received from / sent to. This can be set in the
+		 * osmo_pfcp_endpoint->set_msg_ctx() implementation, up to the caller. If present, this is used for
+		 * logging context, and can also be used by the caller to reduce lookup iterations. */
+		struct osmo_fsm_inst *session_fi;
+		struct osmo_use_count *session_use_count;
+		const char *session_use_token;
+
+		osmo_pfcp_resp_cb resp_cb;
+		void *priv;
+	} ctx;
+};
+
+/* Given a &osmo_pfcp_msg->ies pointer, return the &osmo_pfcp_msg.
+ * In the TLV API, only the 'ies' union is passed around as argument. This macro is useful in error callbacks to obtain
+ * the related osmo_pfcp_msg and thus the logging context pointers (ctx.peer_fi and ctx.session_fi). */
+#define OSMO_PFCP_MSG_FOR_IES(IES_P) ((struct osmo_pfcp_msg *)((char *)IES_P - offsetof(struct osmo_pfcp_msg, ies)))
+
+bool osmo_pfcp_msgtype_is_response(enum osmo_pfcp_message_type message_type);
+
+int osmo_pfcp_ie_f_teid_to_str_buf(char *buf, size_t len, const struct osmo_pfcp_ie_f_teid *ft);
+char *osmo_pfcp_ie_f_teid_to_str_c(void *ctx, const struct osmo_pfcp_ie_f_teid *ft);
+
+int osmo_pfcp_msg_encode(struct msgb *msg, const struct osmo_pfcp_msg *pfcp_msg);
+
+int osmo_pfcp_msg_decode_header(struct osmo_gtlv_load *tlv, struct osmo_pfcp_msg *m,
+				const struct msgb *msg);
+int osmo_pfcp_msg_decode_tlv(struct osmo_pfcp_msg *m, struct osmo_gtlv_load *tlv);
+
+struct osmo_pfcp_msg *osmo_pfcp_msg_alloc_rx(void *ctx, const struct osmo_sockaddr *remote_addr);
+struct osmo_pfcp_msg *osmo_pfcp_msg_alloc_tx(void *ctx, const struct osmo_sockaddr *remote_addr,
+					     const struct osmo_pfcp_ie_node_id *local_node_id,
+					     const struct osmo_pfcp_msg *in_reply_to,
+					     enum osmo_pfcp_message_type msg_type);
+
+void osmo_pfcp_msg_invalidate_ctx(struct osmo_pfcp_msg *m, struct osmo_fsm_inst *deleted_fi);
+
+void osmo_pfcp_msg_free(struct osmo_pfcp_msg *m);
+
+uint32_t osmo_pfcp_next_seq_nr(uint32_t *next_seq_nr_state);
+uint64_t osmo_pfcp_next_seid(uint64_t *next_seid_state);
+
+int osmo_pfcp_ie_node_id_from_osmo_sockaddr(struct osmo_pfcp_ie_node_id *node_id, const struct osmo_sockaddr *os);
+int osmo_pfcp_ie_node_id_to_osmo_sockaddr(const struct osmo_pfcp_ie_node_id *node_id, struct osmo_sockaddr *os);
+
+#define OSMO_PFCP_MSG_MEMB(M, OFS) ((OFS) <= 0 ? NULL : (void *)((uint8_t *)(M) + OFS))
+
+static inline enum osmo_pfcp_cause *osmo_pfcp_msg_cause(const struct osmo_pfcp_msg *m)
+{
+	return OSMO_PFCP_MSG_MEMB(m, m->ofs_cause);
+}
+
+static inline struct osmo_pfcp_ie_node_id *osmo_pfcp_msg_node_id(const struct osmo_pfcp_msg *m)
+{
+	return OSMO_PFCP_MSG_MEMB(m, m->ofs_node_id);
+}
+
+int osmo_pfcp_msg_to_str_buf(char *buf, size_t buflen, const struct osmo_pfcp_msg *m);
+char *osmo_pfcp_msg_to_str_c(void *ctx, const struct osmo_pfcp_msg *m);