check_rtp: on IP:port errors, log the IP and port

Half of those are obviously zero, but I'd rather print the raw data instead of
adding string constants, even if the condition must always lead to 0.0.0.0:0.

Rationale: I had osmo-mgw listen on 0.0.0.0 and got the error message
  DRTP ERROR endpoint:0x1 destination IP-address is invalid
which didn't convey that 0.0.0.0 is regarded as invalid.

Change-Id: I9e98d464a27038904797c5c10735a98ef5b7b9c3
diff --git a/src/libosmo-mgcp/mgcp_network.c b/src/libosmo-mgcp/mgcp_network.c
index de34cc6..7af8e71 100644
--- a/src/libosmo-mgcp/mgcp_network.c
+++ b/src/libosmo-mgcp/mgcp_network.c
@@ -945,22 +945,22 @@
 	 * and IP-address for outgoing data. */
 	if (strcmp(inet_ntoa(conn->end.addr), "0.0.0.0") == 0 && conn->end.rtp_port == 0) {
 		LOGP(DRTP, LOGL_DEBUG,
-		     "endpoint:0x%x destination IP-address and rtp port is (not yet) known\n",
-		     ENDPOINT_NUMBER(endp));
+		     "endpoint:0x%x destination IP-address and rtp port is (not yet) known (%s:%u)\n",
+		     ENDPOINT_NUMBER(endp), inet_ntoa(conn->end.addr), conn->end.rtp_port);
 		return -1;
 	}
 
 	if (strcmp(inet_ntoa(conn->end.addr), "0.0.0.0") == 0) {
 		LOGP(DRTP, LOGL_ERROR,
-		     "endpoint:0x%x destination IP-address is invalid\n",
-		     ENDPOINT_NUMBER(endp));
+		     "endpoint:0x%x destination IP-address is invalid (%s:%u)\n",
+		     ENDPOINT_NUMBER(endp), inet_ntoa(conn->end.addr), conn->end.rtp_port);
 		return -1;
 	}
 
 	if (conn->end.rtp_port == 0) {
 		LOGP(DRTP, LOGL_ERROR,
-		     "endpoint:0x%x destination rtp port is invalid\n",
-		     ENDPOINT_NUMBER(endp));
+		     "endpoint:0x%x destination rtp port is invalid (%s:%u)\n",
+		     ENDPOINT_NUMBER(endp), inet_ntoa(conn->end.addr), conn->end.rtp_port);
 		return -1;
 	}