[mgcp] Add a dummy send method...

This can be used by higher level code to send one dummy
message from the audio port to the network. This can be
used to make the remote discover the nated port of this
endpoint.

1 files changed, 18 insertions, 0 deletions

diff --git a/openbsc/src/mgcp/mgcp_network.c b/openbsc/src/mgcp/mgcp_network.c
index a4ab70c97..e9c86fb66 100644
--- a/openbsc/src/mgcp/mgcp_network.c
+++ b/openbsc/src/mgcp/mgcp_network.c
@@ -73,6 +73,8 @@ enum {
 	PROTO_RTCP,
 };
 
+#define DUMMY_LOAD 0x23
+
 
 static int udp_send(int fd, struct in_addr *addr, int port, char *buf, int len)
 {
@@ -84,6 +86,14 @@ static int udp_send(int fd, struct in_addr *addr, int port, char *buf, int len)
 	return sendto(fd, buf, len, 0, (struct sockaddr *)&out, sizeof(out));
 }
 
+int mgcp_send_dummy(struct mgcp_endpoint *endp)
+{
+	static char buf[] = { DUMMY_LOAD };
+
+	return udp_send(endp->local_rtp.fd, &endp->remote,
+			endp->net_rtp, buf, 1);
+}
+
 static void patch_payload(int payload, char *data, int len)
 {
 	struct rtp_hdr *rtp_hdr;
@@ -163,6 +173,14 @@ static int rtp_data_cb(struct bsc_fd *fd, unsigned int what)
 			LOGP(DMGCP, LOGL_NOTICE, "Found BTS for endpoint: 0x%x on port: %d/%d of %s\n",
 				ENDPOINT_NUMBER(endp), ntohs(endp->bts_rtp), ntohs(endp->bts_rtcp),
 				inet_ntoa(addr.sin_addr));
+
+			/* throw away dummy message */
+			if (rc == 1 && buf[0] == DUMMY_LOAD) {
+				LOGP(DMGCP, LOGL_NOTICE, "Filtered dummy on 0x%x\n",
+				     ENDPOINT_NUMBER(endp));
+				return 0;
+			}
+
 		}
 	}