mgcp: Make the packet loss calculation per session

Somehow we end up with calculations of 65536 for the packet loss
that is RTP_SEQ_MOD. So there might have been a sequence overflow
but no packets to count against it. I have no idea how this can
happen and could not reproduce it. But when we change the SSRC
we should re-initialize the state. Separate the total packets and
octets from the packets we count per SSRC.

Related: OW#1489

2 files changed, 7 insertions, 6 deletions

diff --git a/openbsc/src/libmgcp/mgcp_network.c b/openbsc/src/libmgcp/mgcp_network.c
index c39b627c8..9d627aef0 100644
--- a/openbsc/src/libmgcp/mgcp_network.c
+++ b/openbsc/src/libmgcp/mgcp_network.c
@@ -350,6 +350,7 @@ void mgcp_rtp_annex_count(struct mgcp_endpoint *endp, struct mgcp_rtp_state *sta
 		state->stats_jitter = 0;
 		state->stats_transit = transit;
 		state->stats_cycles = 0;
+		state->stats_packets = 0;
 	} else {
 		uint16_t udelta;
 
@@ -705,6 +706,7 @@ static int rtp_data_net(struct osmo_fd *fd, unsigned int what)
 	}
 
 	proto = fd == &endp->net_end.rtp ? MGCP_PROTO_RTP : MGCP_PROTO_RTCP;
+	endp->net_state.stats_packets += 1;
 	endp->net_end.packets += 1;
 	endp->net_end.octets += rc;
 
@@ -797,6 +799,7 @@ static int rtp_data_bts(struct osmo_fd *fd, unsigned int what)
 	}
 
 	/* do this before the loop handling */
+	endp->bts_state.stats_packets += 1;
 	endp->bts_end.packets += 1;
 	endp->bts_end.octets += rc;
 
@@ -1026,8 +1029,7 @@ int mgcp_free_rtp_port(struct mgcp_rtp_end *end)
 
 
 void mgcp_state_calc_loss(struct mgcp_rtp_state *state,
-			struct mgcp_rtp_end *end, uint32_t *expected,
-			int *loss)
+			uint32_t *expected, int *loss)
 {
 	*expected = state->stats_cycles + state->stats_max_seq;
 	*expected = *expected - state->stats_base_seq + 1;
@@ -1042,8 +1044,8 @@ void mgcp_state_calc_loss(struct mgcp_rtp_state *state,
 	 * Make sure the sign is correct and use the biggest
 	 * positive/negative number that fits.
 	 */
-	*loss = *expected - end->packets;
-	if (*expected < end->packets) {
+	*loss = *expected - state->stats_packets;
+	if (*expected < state->stats_packets) {
 		if (*loss > 0)
 			*loss = INT_MIN;
 	} else {
diff --git a/openbsc/src/libmgcp/mgcp_protocol.c b/openbsc/src/libmgcp/mgcp_protocol.c
index ab98be1d8..4a3ff83c1 100644
--- a/openbsc/src/libmgcp/mgcp_protocol.c
+++ b/openbsc/src/libmgcp/mgcp_protocol.c
@@ -1522,8 +1522,7 @@ void mgcp_format_stats(struct mgcp_endpoint *endp, char *msg, size_t size)
 	uint32_t expected, jitter;
 	int ploss;
 	int nchars;
-	mgcp_state_calc_loss(&endp->net_state, &endp->net_end,
-				&expected, &ploss);
+	mgcp_state_calc_loss(&endp->net_state, &expected, &ploss);
 	jitter = mgcp_state_calc_jitter(&endp->net_state);
 
 	nchars = snprintf(msg, size,