osmo-upf: add VTY 'gtp-echo' command

Allow sending GTPv1-U Echo Requests to GTP peers via new VTY command

  gtp-echo send to (A.B.C.D|X:X::X:X)
  gtp-echo send to (A.B.C.D|X:X::X:X) local-ip (A.B.C.D|X:X::X:X)
  gtp-echo send to (A.B.C.D|X:X::X:X) local-dev DEV_NAME

Related: OS#6541
Change-Id: I970dccd7a27b098eea9e660822e24e2c4b059fc6

include/osmocom/upf/upf.h

@@ -117,6 +117,7 @@ struct g_upf {
 
 	struct {
 		uint32_t next_local_teid_state;
+		uint16_t next_echo_seq_nr;
 	} gtp;
 
 	struct llist_head netinst;

include/osmocom/upf/upf_gtpu_echo.h

@@ -2,3 +2,4 @@
 #pragma once
 
 int upf_gtpu_echo_setup(struct upf_gtp_dev *dev);
+int upf_gtpu_echo_req_tx(struct upf_gtp_dev *dev, const struct osmo_sockaddr *remote, uint16_t seq_nr);

src/osmo-upf/upf_gtpu_echo.c

@@ -122,6 +122,45 @@ static int tx_echo_resp(struct upf_gtp_dev *dev, const struct osmo_sockaddr *rem
 	return rc;
 }
 
+int upf_gtpu_echo_req_tx(struct upf_gtp_dev *dev, const struct osmo_sockaddr *remote, uint16_t seq_nr)
+{
+	struct gtp1u_hdr *tx_h;
+	int rc;
+
+#define GTP_ECHO_REQ_SIZE ((size_t)(sizeof(struct gtp1u_hdr) + 2))
+	uint8_t msgbuf[GTP_ECHO_REQ_SIZE];
+
+	tx_h = (void *)msgbuf;
+	*tx_h = (struct gtp1u_hdr){
+		/* 3GPP TS 29.281 5.1 defines that the ECHO REQ & RESP shall contain a sequence nr */
+		.s = 1,
+		.pt = 1,
+		.version = 1,
+		.msg_type = GTP1U_MSGTYPE_ECHO_REQ,
+		.ext = {
+			.seq_nr = seq_nr,
+		},
+	};
+
+	/* ECHO REQUEST shall contain a recovery counter */
+	tx_h->data2[0] = GTP1U_IEI_RECOVERY;
+	tx_h->data2[1] = g_upf->tunend.recovery_count;
+
+	osmo_store16be(GTP_ECHO_REQ_SIZE - offsetof(struct gtp1u_hdr, data1), &tx_h->length);
+
+	rc = sendto(dev->gtpv1.ofd.fd, msgbuf, GTP_ECHO_REQ_SIZE, 0, &remote->u.sa, sizeof(*remote));
+	if (rc < 0) {
+		rc = -errno;
+		LOG_GTP_DEV(dev, LOGL_ERROR, "GTP1-U sendto(len=%zu, to=%s): %s\n", GTP_ECHO_REQ_SIZE,
+			    osmo_sockaddr_to_str(remote), strerror(-rc));
+	} else {
+		rc = 0;
+	}
+	LOG_GTP_DEV(dev, LOGL_INFO, "<- %s: tx GTP1-U Echo Request: seq_nr=%u recovery_count=%u\n",
+		    osmo_sockaddr_to_str(remote), seq_nr, g_upf->tunend.recovery_count);
+	return rc;
+}
+
 int upf_gtpu_echo_read_cb(struct osmo_fd *ofd, unsigned int what)
 {
 	struct upf_gtp_dev *dev = ofd->data;

src/osmo-upf/upf_vty.c

@@ -38,6 +38,7 @@
 #include <osmocom/upf/up_session.h>
 #include <osmocom/upf/up_gtp_action.h>
 #include <osmocom/upf/netinst.h>
+#include <osmocom/upf/upf_gtpu_echo.h>
 
 enum upf_vty_node {
 	PFCP_NODE = _LAST_OSMOVTY_NODE + 1,
@@ -486,6 +487,105 @@ DEFUN(show_session, show_session_cmd,
 	return CMD_SUCCESS;
 }
 
+/* variant:
+ *  0 "gtp-echo send to (A.B.C.D|X:X::X:X)"
+ *  1 "gtp-echo send to (A.B.C.D|X:X::X:X) local-ip (A.B.C.D|X:X::X:X)"
+ *  2 "gtp-echo send to (A.B.C.D|X:X::X:X) local-dev DEV_NAME"
+ */
+int _gtp_echo_tx(struct vty *vty, int variant, int argc, const char **argv)
+{
+	struct osmo_sockaddr_str addr;
+	struct osmo_sockaddr osa_remote;
+	struct osmo_sockaddr osa_local;
+	struct upf_gtp_dev *gtp_dev = NULL;
+	const char *remote_str = argv[0];
+	const char *local_str = NULL;
+	if (argc > 1)
+		local_str = argv[1];
+
+	/* GTP can be received on port 2152 only, i.e. the remote port must be 2152. (The sending port is allowed to
+	 * differ). */
+	if (osmo_sockaddr_str_from_str(&addr, remote_str, 2152)
+	    || osmo_sockaddr_str_to_osa(&addr, &osa_remote)) {
+		vty_out(vty, "%% Error: cannot send Echo: invalid IP address: %s%s",
+			osmo_quote_str(remote_str, -1), VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
+	switch (variant) {
+	case 0:
+		gtp_dev = llist_first_entry_or_null(&g_upf->tunend.devs, struct upf_gtp_dev, entry);
+		if (!gtp_dev) {
+			vty_out(vty, "%% Error: cannot send Echo: there is no GTP device%s",
+				VTY_NEWLINE);
+			return CMD_WARNING;
+		}
+		break;
+	case 1:
+		if (osmo_sockaddr_str_from_str(&addr, local_str, 2152)
+		    || osmo_sockaddr_str_to_osa(&addr, &osa_local)) {
+			vty_out(vty, "%% Error: cannot send Echo: invalid IP address: %s%s",
+				osmo_quote_str(local_str, -1), VTY_NEWLINE);
+			return CMD_WARNING;
+		}
+		gtp_dev = upf_gtp_dev_find_by_local_addr(&osa_local);
+		if (!gtp_dev) {
+			vty_out(vty, "%% Error: cannot send Echo: this does not seem to be a locally bound GTP address: %s%s",
+				osmo_sockaddr_to_str_c(OTC_SELECT, &osa_local), VTY_NEWLINE);
+			return CMD_WARNING;
+		}
+		break;
+	case 2:
+		gtp_dev = upf_gtp_dev_find_by_name(local_str);
+		if (!gtp_dev) {
+			vty_out(vty, "%% Error: cannot send Echo: there is no GTP device by the name of '%s'%s",
+				local_str, VTY_NEWLINE);
+			return CMD_WARNING;
+		}
+		break;
+	}
+	OSMO_ASSERT(gtp_dev);
+
+	if (upf_gtpu_echo_req_tx(gtp_dev, &osa_remote, g_upf->gtp.next_echo_seq_nr++)) {
+		vty_out(vty, "%% Error: Failed to transmit Echo Request (see DGTP logging)%s", VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+	vty_out(vty, "%s -> %s tx Echo Request; for responses, see DGTP logging level INFO%s",
+		gtp_dev->name, osmo_sockaddr_to_str_c(OTC_SELECT, &osa_remote), VTY_NEWLINE);
+	return CMD_SUCCESS;
+}
+
+#define IP46_STR "IPv4 address\nIPv6 address\n"
+#define GTP_ECHO_TX_STR \
+      "GTP1-U Echo probing\n" \
+      "Send a GTP1-U Echo Request to a remote peer\n" \
+      "Send to remote peer's GTP address\n" IP46_STR
+
+DEFUN(gtp_echo_tx, gtp_echo_tx_cmd,
+      "gtp-echo send to (A.B.C.D|X:X::X:X)",
+      GTP_ECHO_TX_STR)
+{
+	return _gtp_echo_tx(vty, 0, argc, argv);
+}
+
+DEFUN(gtp_echo_tx_local_ip, gtp_echo_tx_local_ip_cmd,
+      "gtp-echo send to (A.B.C.D|X:X::X:X) local-ip (A.B.C.D|X:X::X:X)",
+      GTP_ECHO_TX_STR
+      "Send from local GTP device, chosen by IP address\n"
+      IP46_STR)
+{
+	return _gtp_echo_tx(vty, 1, argc, argv);
+}
+
+DEFUN(gtp_echo_tx_local_dev, gtp_echo_tx_local_dev_cmd,
+      "gtp-echo send to (A.B.C.D|X:X::X:X) local-dev DEV_NAME",
+      GTP_ECHO_TX_STR
+      "Send from local GTP device, chosen by name as configured in 'dev create' or 'dev use'.\n"
+      "A GTP device name as it appears in the cfg\n")
+{
+	return _gtp_echo_tx(vty, 2, argc, argv);
+}
+
 void upf_vty_init()
 {
 	OSMO_ASSERT(g_upf != NULL);
@@ -495,6 +595,9 @@ void upf_vty_init()
 	install_element_ve(&show_session_cmd);
 	install_element_ve(&show_netinst_cmd);
 	install_element_ve(&show_nft_rule_append_cmd);
+	install_element_ve(&gtp_echo_tx_cmd);
+	install_element_ve(&gtp_echo_tx_local_ip_cmd);
+	install_element_ve(&gtp_echo_tx_local_dev_cmd);
 
 	install_node(&cfg_pfcp_node, config_write_pfcp);
 	install_element(CONFIG_NODE, &cfg_pfcp_cmd);

tests/gtp-echo.vty

@@ -0,0 +1,42 @@
+OsmoUPF> list
+...
+  gtp-echo send to (A.B.C.D|X:X::X:X)
+  gtp-echo send to (A.B.C.D|X:X::X:X) local-ip (A.B.C.D|X:X::X:X)
+  gtp-echo send to (A.B.C.D|X:X::X:X) local-dev DEV_NAME
+...
+OsmoUPF> enable
+OsmoUPF# list
+...
+  gtp-echo send to (A.B.C.D|X:X::X:X)
+  gtp-echo send to (A.B.C.D|X:X::X:X) local-ip (A.B.C.D|X:X::X:X)
+  gtp-echo send to (A.B.C.D|X:X::X:X) local-dev DEV_NAME
+...
+OsmoUPF# configure terminal
+OsmoUPF(config)# list
+... !gtp-echo
+OsmoUPF(config)# end
+
+OsmoUPF# gtp-echo?
+  gtp-echo  GTP1-U Echo probing
+OsmoUPF# gtp-echo ?
+  send  Send a GTP1-U Echo Request to a remote peer
+OsmoUPF# gtp-echo send ?
+  to  Send to remote peer's GTP address
+OsmoUPF# gtp-echo send to ?
+  A.B.C.D   IPv4 address
+  X:X::X:X  IPv6 address
+OsmoUPF# gtp-echo send to 1.2.3.4 ?
+  local-ip   Send from local GTP device, chosen by IP address
+  local-dev  Send from local GTP device, chosen by name as configured in 'dev create' or 'dev use'.
+  <cr>       
+OsmoUPF# gtp-echo send to 1.2.3.4 local-ip ?
+  A.B.C.D   IPv4 address
+  X:X::X:X  IPv6 address
+OsmoUPF# gtp-echo send to 1.2.3.4 local-dev ?
+  DEV_NAME  A GTP device name as it appears in the cfg
+OsmoUPF# gtp-echo send to 1.2.3.4
+% Error: cannot send Echo: there is no GTP device
+OsmoUPF# gtp-echo send to 1.2.3.4 local-ip 1.2.3.4
+% Error: cannot send Echo: this does not seem to be a locally bound GTP address: 1.2.3.4:2152
+OsmoUPF# gtp-echo send to 1.2.3.4 local-dev apn0
+% Error: cannot send Echo: there is no GTP device by the name of 'apn0'