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, 9 insertions, 4 deletions

diff --git a/openbsc/src/osmo-bsc_nat/bsc_nat.c b/openbsc/src/osmo-bsc_nat/bsc_nat.c
index 2d4f2a801..04c12e33f 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_nat.c
+++ b/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);