SIGTRAN: add function to check connection existence

Add convenience helper to check if particular connection ID exists and use it to
properly report errors when attempting to send messages over non-existent connections.

Change-Id: Iffedf55b4c292ee6b2f97bcdeef6dc13c050ce01

4 files changed, 36 insertions, 6 deletions

diff --git a/examples/sccp_test_vty.c b/examples/sccp_test_vty.c
index 044ecf2..3f644e2 100644
--- a/examples/sccp_test_vty.c
+++ b/examples/sccp_test_vty.c
@@ -41,11 +41,16 @@ DEFUN(scu_conn_req, scu_conn_req_cmd,
 	"Connection ID\n")
 {
 	struct osmo_sccp_user *scu = vty->index;
-	int conn_id = atoi(argv[0]);
+	int rc, conn_id = atoi(argv[0]);
 	const char *data = argv[1];
 
-	osmo_sccp_tx_conn_req(scu, conn_id, &g_calling_addr, &g_called_addr,
-				(const uint8_t *)data, data ? strlen(data)+1 : 0);
+	rc = osmo_sccp_tx_conn_req(scu, conn_id, &g_calling_addr, &g_called_addr,
+							   (const uint8_t *)data, data ? strlen(data) + 1 : 0);
+	if (rc < 0) {
+		vty_out(vty, "Error while sending N-CONNECT.req: %s%s", strerror(-rc), VTY_NEWLINE);
+		return CMD_WARNING;
+	}
+
 	return CMD_SUCCESS;
 }
 
diff --git a/include/osmocom/sigtran/sccp_helpers.h b/include/osmocom/sigtran/sccp_helpers.h
index dc4e115..a575169 100644
--- a/include/osmocom/sigtran/sccp_helpers.h
+++ b/include/osmocom/sigtran/sccp_helpers.h
@@ -67,5 +67,7 @@ int osmo_sccp_addr_to_id_buf(char *buf, size_t buf_len, const struct osmo_ss7_in
 			      const struct osmo_sccp_addr *addr);
 char *osmo_sccp_addr_to_id_c(void *ctx, const struct osmo_ss7_instance *ss7, const struct osmo_sccp_addr *addr);
 
+bool osmo_sccp_conn_id_exists(const struct osmo_sccp_instance *inst, uint32_t id);
+
 char *osmo_sccp_addr_name(const struct osmo_ss7_instance *ss7, const struct osmo_sccp_addr *addr);
 char *osmo_sccp_inst_addr_name(const struct osmo_sccp_instance *sccp, const struct osmo_sccp_addr *addr);
diff --git a/src/sccp_helpers.c b/src/sccp_helpers.c
index 2dc762e..266c869 100644
--- a/src/sccp_helpers.c
+++ b/src/sccp_helpers.c
@@ -21,6 +21,7 @@
  *
  */
 
+#include <errno.h>
 #include <string.h>
 #include <stdbool.h>
 
@@ -152,9 +153,15 @@ int osmo_sccp_tx_conn_req_msg(struct osmo_sccp_user *scu, uint32_t conn_id,
 int osmo_sccp_tx_data(struct osmo_sccp_user *scu, uint32_t conn_id,
 		      const uint8_t *data, unsigned int len)
 {
-	struct msgb *msg = scu_msgb_alloc(__func__);
+	struct msgb *msg;
 	struct osmo_scu_prim *prim;
 
+	if (!osmo_sccp_conn_id_exists(scu->inst, conn_id)) {
+		LOGP(DLSCCP, LOGL_ERROR, "N-DATA.req TX error: unable to find connection ID (local_ref) %u\n", conn_id);
+		return -ENOTCONN;
+	}
+
+	msg = scu_msgb_alloc(__func__);
 	prim = (struct osmo_scu_prim *) msgb_put(msg, sizeof(*prim));
 	osmo_prim_init(&prim->oph, SCCP_SAP_USER,
 			OSMO_SCU_PRIM_N_DATA,
@@ -183,10 +190,16 @@ int osmo_sccp_tx_disconn(struct osmo_sccp_user *scu, uint32_t conn_id,
 			 const struct osmo_sccp_addr *resp_addr,
 			 uint32_t cause)
 {
-	struct msgb *msg = scu_msgb_alloc(__func__);
+	struct msgb *msg;
 	struct osmo_scu_prim *prim;
 	struct osmo_scu_disconn_param *param;
 
+	if (!osmo_sccp_conn_id_exists(scu->inst, conn_id)) {
+		LOGP(DLSCCP, LOGL_ERROR, "N-DISCONNECT.req TX error: unable to find connection ID (local_ref) %u\n", conn_id);
+		return -ENOTCONN;
+	}
+
+	msg = scu_msgb_alloc(__func__);
 	prim = (struct osmo_scu_prim *) msgb_put(msg, sizeof(*prim));
 	osmo_prim_init(&prim->oph, SCCP_SAP_USER,
 			OSMO_SCU_PRIM_N_DISCONNECT,
@@ -210,6 +223,11 @@ int osmo_sccp_tx_conn_resp_msg(struct osmo_sccp_user *scu, uint32_t conn_id,
 	struct osmo_scu_prim *prim;
 	struct osmo_scu_connect_param *param;
 
+	if (!osmo_sccp_conn_id_exists(scu->inst, conn_id)) {
+		LOGP(DLSCCP, LOGL_ERROR, "N-CONNECT.resp TX error: unable to find connection ID (local_ref) %u\n", conn_id);
+		return -ENOTCONN;
+	}
+
 	msg->l2h = msg->data;
 
 	prim = (struct osmo_scu_prim *) msgb_push(msg, sizeof(*prim));
diff --git a/src/sccp_scoc.c b/src/sccp_scoc.c
index b85eeb9..3b1ca02 100644
--- a/src/sccp_scoc.c
+++ b/src/sccp_scoc.c
@@ -446,7 +446,7 @@ static void conn_stop_connect_timer(struct sccp_connection *conn)
 
 static void conn_destroy(struct sccp_connection *conn);
 
-static struct sccp_connection *conn_find_by_id(struct osmo_sccp_instance *inst, uint32_t id)
+static struct sccp_connection *conn_find_by_id(const struct osmo_sccp_instance *inst, uint32_t id)
 {
 	struct sccp_connection *conn;
 
@@ -457,6 +457,11 @@ static struct sccp_connection *conn_find_by_id(struct osmo_sccp_instance *inst,
 	return NULL;
 }
 
+bool osmo_sccp_conn_id_exists(const struct osmo_sccp_instance *inst, uint32_t id)
+{
+	return conn_find_by_id(inst, id) ? true : false;
+}
+
 #define INIT_TIMER(x, fn, priv)		do { (x)->cb = fn; (x)->data = priv; } while (0)
 
 /* allocate + init a SCCP Connection with given ID */