mgcp: add voice muxer support

This patch adds the voice muxer. You can use this to batch RTP
traffic to reduce bandwidth comsuption. Basically, osmux transforms
RTP flows to a compact batch format, that is later on decompacted
to its original form. Port UDP/1984 is used for the muxer traffic
between osmo-bsc_nat and osmo-bsc_mgcp (in the BSC side). This
feature depends on libosmo-netif, which contains the osmux core
support.

Osmux is requested on-demand via the MGCP CRCX/MDCX messages (using
the vendor-specific extension X-Osmux: on) coming from the BSC-NAT,
so you can selectively enable osmux per BSC from one the bsc-nat.cfg
file, so we have a centralized point to enable/disable osmux.

First thing you need to do is to accept requests to use Osmux,
this can be done from VTY interface of osmo-bsc_nat and
osmo-bsc_mgcp by adding the following line:

mgcp
  ...
  osmux on
  osmux batch-factor 4

This just initializes the osmux engine. You still have to specify
what BSC uses osmux from osmo-bsc_nat configuration file:

...
 bsc 1
  osmux on
 bsc 2
  ...
 bsc 3
  osmux on

In this case, bsc 1 and 3 should use osmux if possible, bsc 2 does
not have osmux enabled.

Thus, you can selectively enable osmux depending on the BSC, and
we have a centralized point for configuration from the bsc-nat to
enable osmux on demand, as suggested by Holger.

At this moment, this patch contains heavy debug logging for each
RTP packet that can be removed later to save cycles.

The RTP ssrc/seqnum/timestamp is randomly allocated for each MDCX that
is received to configure an endpoint.

1 files changed, 41 insertions, 21 deletions

diff --git a/openbsc/src/libmgcp/mgcp_network.c b/openbsc/src/libmgcp/mgcp_network.c
index 8a5656a83..7c6926d28 100644
--- a/openbsc/src/libmgcp/mgcp_network.c
+++ b/openbsc/src/libmgcp/mgcp_network.c
@@ -35,6 +35,8 @@
 #include <openbsc/mgcp.h>
 #include <openbsc/mgcp_internal.h>
 
+#include <openbsc/osmux.h>
+
 #warning "Make use of the rtp proxy code"
 
 /* attempt to determine byte order */
@@ -78,20 +80,11 @@ struct rtp_hdr {
 #define RTP_MAX_DROPOUT		3000
 #define RTP_MAX_MISORDER	100
 
-
-enum {
-	MGCP_DEST_NET = 0,
-	MGCP_DEST_BTS,
-};
-
 enum {
 	MGCP_PROTO_RTP,
 	MGCP_PROTO_RTCP,
 };
 
-#define MGCP_DUMMY_LOAD 0x23
-
-
 /**
  * This does not need to be a precision timestamp and
  * is allowed to wrap quite fast. The returned value is
@@ -118,8 +111,7 @@ static uint32_t get_current_ts(unsigned unit)
 	return ret;
 }
 
-static int mgcp_udp_send(int fd, struct in_addr *addr, int port, char *buf,
-			 int len)
+int mgcp_udp_send(int fd, struct in_addr *addr, int port, char *buf, int len)
 {
 	struct sockaddr_in out;
 	out.sin_family = AF_INET;
@@ -567,8 +559,8 @@ static int mgcp_send_transcoder(struct mgcp_rtp_end *end,
 	return rc;
 }
 
-static int mgcp_send(struct mgcp_endpoint *endp, int dest, int is_rtp,
-		     struct sockaddr_in *addr, char *buf, int rc)
+int mgcp_send(struct mgcp_endpoint *endp, int dest, int is_rtp,
+	      struct sockaddr_in *addr, char *buf, int rc)
 {
 	struct mgcp_trunk_config *tcfg = endp->tcfg;
 	struct mgcp_rtp_end *rtp_end;
@@ -587,10 +579,22 @@ static int mgcp_send(struct mgcp_endpoint *endp, int dest, int is_rtp,
 		rtp_end = &endp->net_end;
 		rtp_state = &endp->bts_state;
 		tap_idx = MGCP_TAP_NET_OUT;
+
+			LOGP(DMGCP, LOGL_DEBUG, "delivering RTP to Network"
+						"via addr=%s, port=%u\n",
+				inet_ntoa(endp->net_end.addr),
+				ntohs(endp->net_end.rtp_port));
+
 	} else {
 		rtp_end = &endp->bts_end;
 		rtp_state = &endp->net_state;
 		tap_idx = MGCP_TAP_BTS_OUT;
+
+			LOGP(DMGCP, LOGL_DEBUG, "delivering RTP to BTS"
+						"via addr=%s, port=%u\n",
+				inet_ntoa(endp->bts_end.addr),
+				ntohs(endp->bts_end.rtp_port));
+
 	}
 
 	if (!rtp_end->output_enabled)
@@ -655,12 +659,20 @@ static int rtp_data_net(struct osmo_fd *fd, unsigned int what)
 		return -1;
 	}
 
-	if (endp->net_end.rtp_port != addr.sin_port &&
-	    endp->net_end.rtcp_port != addr.sin_port) {
-		LOGP(DMGCP, LOGL_ERROR,
-			"Data from wrong source port %d on 0x%x\n",
-			ntohs(addr.sin_port), ENDPOINT_NUMBER(endp));
-		return -1;
+	switch(endp->type) {
+	case MGCP_RTP_DEFAULT:
+	case MGCP_RTP_TRANSCODED:
+		if (endp->net_end.rtp_port != addr.sin_port &&
+		    endp->net_end.rtcp_port != addr.sin_port) {
+			LOGP(DMGCP, LOGL_ERROR,
+				"Data from wrong source port %d on 0x%x\n",
+				ntohs(addr.sin_port), ENDPOINT_NUMBER(endp));
+			return -1;
+		}
+		break;
+	case MGCP_OSMUX_BSC:
+	case MGCP_OSMUX_BSC_NAT:
+		break;
 	}
 
 	/* throw away the dummy message */
@@ -683,6 +695,10 @@ static int rtp_data_net(struct osmo_fd *fd, unsigned int what)
 	case MGCP_RTP_TRANSCODED:
 		return mgcp_send_transcoder(&endp->trans_net, endp->cfg,
 					    proto == MGCP_PROTO_RTP, buf, rc);
+	case MGCP_OSMUX_BSC_NAT:
+		return osmux_xfrm_to_osmux(MGCP_DEST_BTS, buf, rc, endp);
+	case MGCP_OSMUX_BSC:	/* Should not happen */
+		break;
 	}
 
 	LOGP(DMGCP, LOGL_ERROR, "Bad MGCP type %u on endpoint %u\n",
@@ -771,6 +787,11 @@ static int rtp_data_bts(struct osmo_fd *fd, unsigned int what)
 	case MGCP_RTP_TRANSCODED:
 		return mgcp_send_transcoder(&endp->trans_bts, endp->cfg,
 					    proto == MGCP_PROTO_RTP, buf, rc);
+	case MGCP_OSMUX_BSC:
+		/* OSMUX translation: BTS -> BSC */
+		return osmux_xfrm_to_osmux(MGCP_DEST_NET, buf, rc, endp);
+	case MGCP_OSMUX_BSC_NAT:
+		break;	/* Should not happen */
 	}
 
 	LOGP(DMGCP, LOGL_ERROR, "Bad MGCP type %u on endpoint %u\n",
@@ -835,8 +856,7 @@ static int rtp_data_trans_bts(struct osmo_fd *fd, unsigned int what)
 	return rtp_data_transcoder(&endp->trans_bts, endp, MGCP_DEST_BTS, fd);
 }
 
-static int mgcp_create_bind(const char *source_addr, struct osmo_fd *fd,
-			    int port)
+int mgcp_create_bind(const char *source_addr, struct osmo_fd *fd, int port)
 {
 	struct sockaddr_in addr;
 	int on = 1;