gsup_client: allow passing a unit id to identify with HLR

Before, each GSUP client would contact the HLR with an identical unit id, i.e.
"SGSN-00-00-00-00-00-00", with the result that some messages were sucked off by
the wrong client.

Pass explicit unit name from each gsup client user, so that OsmoMSC is "MSC"
and OsmoSGSN is "SGSN". Hence the HLR can properly route the messages.

Todo: also set some values instead of the zeros.

Unrelated cosmetic change while editing the arguments: gsup_client_create()'s
definition's oap client config arg name mismatched the one used in the
declaration. Use oapc_config in both.

Change-Id: I0a60681ab4a4d73e26fe8f0637447db4b6fe6eb2

include/openbsc/gsup_client.h

@@ -37,6 +37,8 @@ typedef int (*gsup_client_read_cb_t)(struct gsup_client *gsupc,
 				     struct msgb *msg);
 
 struct gsup_client {
+	const char *unit_name;
+
 	struct ipa_client_conn *link;
 	gsup_client_read_cb_t read_cb;
 	void *data;
@@ -49,10 +51,11 @@ struct gsup_client {
 	int got_ipa_pong;
 };
 
-struct gsup_client *gsup_client_create(const char *ip_addr,
+struct gsup_client *gsup_client_create(const char *unit_name,
+				       const char *ip_addr,
 				       unsigned int tcp_port,
 				       gsup_client_read_cb_t read_cb,
-				       struct oap_client_config *oap_config);
+				       struct oap_client_config *oapc_config);
 
 void gsup_client_destroy(struct gsup_client *gsupc);
 int gsup_client_send(struct gsup_client *gsupc, struct msgb *msg);

src/gprs/gprs_subscriber.c

@@ -69,6 +69,7 @@ int gprs_subscr_init(struct sgsn_instance *sgi)
 	addr_str = inet_ntoa(sgi->cfg.gsup_server_addr.sin_addr);
 
 	sgi->gsup_client = gsup_client_create(
+		"SGSN",
 		addr_str, sgi->cfg.gsup_server_port,
 		&gsup_read_cb,
 		&sgi->cfg.oap);

src/libcommon/gsup_client.c

@@ -173,10 +173,13 @@ static int gsup_client_read_cb(struct ipa_client_conn *link, struct msgb *msg)
 	struct ipaccess_head_ext *he = (struct ipaccess_head_ext *) msgb_l2(msg);
 	struct gsup_client *gsupc = (struct gsup_client *)link->data;
 	int rc;
-	static struct ipaccess_unit ipa_dev = {
-		.unit_name = "SGSN"
+	struct ipaccess_unit ipa_dev = {
+		/* see gsup_client_create() on const vs non-const */
+		.unit_name = (char*)gsupc->unit_name,
 	};
 
+	OSMO_ASSERT(ipa_dev.unit_name);
+
 	msg->l2h = &hh->data[0];
 
 	rc = ipaccess_bts_handle_ccm(link, &ipa_dev, msg);
@@ -262,7 +265,8 @@ static void start_test_procedure(struct gsup_client *gsupc)
 	gsup_client_send_ping(gsupc);
 }
 
-struct gsup_client *gsup_client_create(const char *ip_addr,
+struct gsup_client *gsup_client_create(const char *unit_name,
+				       const char *ip_addr,
 				       unsigned int tcp_port,
 				       gsup_client_read_cb_t read_cb,
 				       struct oap_client_config *oapc_config)
@@ -273,6 +277,12 @@ struct gsup_client *gsup_client_create(const char *ip_addr,
 	gsupc = talloc_zero(tall_bsc_ctx, struct gsup_client);
 	OSMO_ASSERT(gsupc);
 
+	/* struct ipaccess_unit has a non-const unit_name, so let's copy to be
+	 * able to have a non-const unit_name here as well. To not taint the
+	 * public gsup_client API, let's store it in a const char* anyway. */
+	gsupc->unit_name = talloc_strdup(gsupc, unit_name);
+	OSMO_ASSERT(gsupc->unit_name);
+
 	/* a NULL oapc_config will mark oap_state disabled. */
 	rc = oap_client_init(oapc_config, &gsupc->oap_state);
 	if (rc != 0)

src/libcommon/gsup_test_client.c

@@ -275,8 +275,8 @@ int main(int argc, char **argv)
 
 	osmo_init_logging(&gsup_test_client_log_info);
 
-	g_gc = gsup_client_create(server_host, server_port, gsupc_read_cb,
-				       NULL);
+	g_gc = gsup_client_create("GSUPTEST", server_host, server_port,
+				  gsupc_read_cb, NULL);
 
 
 	signal(SIGINT, sig_cb);