enable telnet VTY bind address config for various programs

Following the 'line vty'/'bind A.B.C.D' command added in libosmocore, use the
configured address to set the telnet bind for the VTY line. It is now possible
to publish the VTY on a specific local interface (including 0.0.0.0 aka "any").

Implement in all of:
  osmo-gbproxy
  osmo-gtphub
  osmo-sgsn
  osmo-bsc
  osmo-bsc_nat
  osmo-bsc_mgcp
  osmo-nitb

In some of these main programs, move the telnet initialization below the
configuration parsing.

Historically, this was not a good idea for programs using bsc_init.c (aka
bsc_bootstrap_network()), since they expected a gsm_network struct pointer in
((struct telnet_connection*)vty->priv)->priv, so that telnet had to be either
initialized or replaced by a dummy struct. In the meantime, the gsm_network
struct is not actually looked up in a priv pointer but in the static bsc_vty.c
scope (bsc_gsmnet), so this limitation is mere legacy (even though said legacy
is still there in an "#if 0" chunk).

In the other binaries I have briefly looked at the init sequence dependencies
and found no reason to initialize telnet above the config file parsing. In any
case, I have tested every single one of abovementioned binaries to verify that
they still parse the example config successfully and launch, allowing VTY
connections on the configured address(es). I hope this suffices.

In all of the above, log VTY address and port. LOGL_INFO is disabled by default
in some of the logging scopes, and since it is a single log message right at
program launch, I decided for the slightly more aggressive LOGL_NOTICE.

openbsc/src/gprs/gb_proxy_main.c

@@ -252,10 +252,6 @@ int main(int argc, char **argv)
 	rate_ctr_init(tall_bsc_ctx);
 	osmo_stats_init(tall_bsc_ctx);
 
-	rc = telnet_init(tall_bsc_ctx, &dummy_network, OSMO_VTY_PORT_GBPROXY);
-	if (rc < 0)
-		exit(1);
-
 	bssgp_nsi = gprs_ns_instantiate(&proxy_ns_cb, tall_bsc_ctx);
 	if (!bssgp_nsi) {
 		LOGP(DGPRS, LOGL_ERROR, "Unable to instantiate NS\n");
@@ -274,6 +270,14 @@ int main(int argc, char **argv)
 		exit(2);
 	}
 
+	/* start telnet after reading config for vty_get_bind_addr() */
+	LOGP(DGPRS, LOGL_NOTICE, "VTY at %s %d\n",
+	     vty_get_bind_addr(), OSMO_VTY_PORT_GBPROXY);
+	rc = telnet_init_dynif(tall_bsc_ctx, &dummy_network,
+			       vty_get_bind_addr(), OSMO_VTY_PORT_GBPROXY);
+	if (rc < 0)
+		exit(1);
+
 	if (!gprs_nsvc_by_nsei(gbcfg.nsi, gbcfg.nsip_sgsn_nsei)) {
 		LOGP(DGPRS, LOGL_FATAL, "You cannot proxy to NSEI %u "
 			"without creating that NSEI before\n",

openbsc/src/gprs/gtphub_main.c

@@ -314,9 +314,6 @@ int main(int argc, char **argv)
         gtphub_vty_init(hub, cfg);
 
 	rate_ctr_init(osmo_gtphub_ctx);
-	rc = telnet_init(osmo_gtphub_ctx, 0, OSMO_VTY_PORT_GTPHUB);
-	if (rc < 0)
-		exit(1);
 
 	handle_options(ccfg, argc, argv);
 
@@ -327,6 +324,14 @@ int main(int argc, char **argv)
 		exit(2);
 	}
 
+	/* start telnet after reading config for vty_get_bind_addr() */
+	LOGP(DGTPHUB, LOGL_NOTICE, "VTY at %s %d\n",
+	     vty_get_bind_addr(), OSMO_VTY_PORT_GTPHUB);
+	rc = telnet_init_dynif(osmo_gtphub_ctx, 0, vty_get_bind_addr(),
+			       OSMO_VTY_PORT_GTPHUB);
+	if (rc < 0)
+		exit(1);
+
 	if (gtphub_start(hub, cfg,
 			 next_restart_count(ccfg->restart_counter_file))
 	    != 0)

openbsc/src/gprs/sgsn_main.c

@@ -315,9 +315,6 @@ int main(int argc, char **argv)
 	handle_options(argc, argv);
 
 	rate_ctr_init(tall_bsc_ctx);
-	rc = telnet_init(tall_bsc_ctx, &dummy_network, OSMO_VTY_PORT_SGSN);
-	if (rc < 0)
-		exit(1);
 
 	ctrl = sgsn_controlif_setup(NULL, OSMO_CTRL_PORT_SGSN);
 	if (!ctrl) {
@@ -357,6 +354,14 @@ int main(int argc, char **argv)
 		exit(2);
 	}
 
+	/* start telnet after reading config for vty_get_bind_addr() */
+	LOGP(DGPRS, LOGL_NOTICE, "VTY at %s %d\n",
+	     vty_get_bind_addr(), OSMO_VTY_PORT_SGSN);
+	rc = telnet_init_dynif(tall_bsc_ctx, &dummy_network,
+			       vty_get_bind_addr(), OSMO_VTY_PORT_SGSN);
+	if (rc < 0)
+		exit(1);
+
 	rc = sgsn_gtp_init(&sgsn_inst);
 	if (rc) {
 		LOGP(DGPRS, LOGL_FATAL, "Cannot bind/listen on GTP socket\n");

openbsc/src/libbsc/bsc_init.c

@@ -495,7 +495,11 @@ int bsc_bootstrap_network(int (*mncc_recv)(struct gsm_network *, struct msgb *),
 		return rc;
 	}
 
-	rc = telnet_init(tall_bsc_ctx, bsc_gsmnet, OSMO_VTY_PORT_NITB_BSC);
+	/* start telnet after reading config for vty_get_bind_addr() */
+	LOGP(DNM, LOGL_NOTICE, "VTY at %s %d\n",
+	     vty_get_bind_addr(), OSMO_VTY_PORT_NITB_BSC);
+	rc = telnet_init_dynif(tall_bsc_ctx, bsc_gsmnet, vty_get_bind_addr(),
+			       OSMO_VTY_PORT_NITB_BSC);
 	if (rc < 0)
 		return rc;
 

openbsc/src/osmo-bsc_mgcp/mgcp_main.c

@@ -232,7 +232,11 @@ int main(int argc, char **argv)
 	if (rc < 0)
 		return rc;
 
-	rc = telnet_init(tall_bsc_ctx, &dummy_network, OSMO_VTY_PORT_BSC_MGCP);
+	/* start telnet after reading config for vty_get_bind_addr() */
+	LOGP(DMGCP, LOGL_NOTICE, "VTY at %s %d\n",
+	     vty_get_bind_addr(), OSMO_VTY_PORT_BSC_MGCP);
+	rc = telnet_init_dynif(tall_bsc_ctx, &dummy_network,
+			       vty_get_bind_addr(), OSMO_VTY_PORT_BSC_MGCP);
 	if (rc < 0)
 		return rc;
 

openbsc/src/osmo-bsc_nat/bsc_nat.c

@@ -1628,15 +1628,20 @@ int main(int argc, char **argv)
 	osmo_stats_init(tall_bsc_ctx);
 
 	/* init vty and parse */
-	if (telnet_init(tall_bsc_ctx, NULL, OSMO_VTY_PORT_BSC_NAT)) {
-		fprintf(stderr, "Creating VTY telnet line failed\n");
-		return -5;
-	}
 	if (mgcp_parse_config(config_file, nat->mgcp_cfg, MGCP_BSC_NAT) < 0) {
 		fprintf(stderr, "Failed to parse the config file: '%s'\n", config_file);
 		return -3;
 	}
 
+	/* start telnet after reading config for vty_get_bind_addr() */
+	LOGP(DNAT, LOGL_NOTICE, "VTY at %s %d\n",
+	     vty_get_bind_addr(), OSMO_VTY_PORT_BSC_NAT);
+	if (telnet_init_dynif(tall_bsc_ctx, NULL, vty_get_bind_addr(),
+			      OSMO_VTY_PORT_BSC_NAT)) {
+		fprintf(stderr, "Creating VTY telnet line failed\n");
+		return -5;
+	}
+
 	/* over rule the VTY config for MSC IP */
 	if (msc_ip)
 		bsc_nat_set_msc_ip(nat, msc_ip);