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.

1 files changed, 8 insertions, 3 deletions

diff --git a/openbsc/src/gprs/sgsn_main.c b/openbsc/src/gprs/sgsn_main.c
index 2d3a0e4a9..b10b0b37f 100644
--- a/openbsc/src/gprs/sgsn_main.c
+++ b/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");