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

5 files changed, 12 insertions, 11 deletions

diff --git a/openbsc/include/openbsc/mgcp_internal.h b/openbsc/include/openbsc/mgcp_internal.h
index 1f836595b..076fa4a4b 100644
--- a/openbsc/include/openbsc/mgcp_internal.h
+++ b/openbsc/include/openbsc/mgcp_internal.h
@@ -72,6 +72,7 @@ struct mgcp_rtp_state {
 	uint32_t stats_jitter;
 	int32_t stats_transit;
 	int stats_cycles;
+	unsigned int stats_packets;
 };
 
 struct mgcp_rtp_codec {
@@ -273,8 +274,7 @@ void mgcp_rtp_end_config(struct mgcp_endpoint *endp, int expect_ssrc_change,
 uint32_t mgcp_rtp_packet_duration(struct mgcp_endpoint *endp,
 				  struct mgcp_rtp_end *rtp);
 
-void mgcp_state_calc_loss(struct mgcp_rtp_state *s, struct mgcp_rtp_end *,
-			uint32_t *expected, int *loss);
+void mgcp_state_calc_loss(struct mgcp_rtp_state *s, uint32_t *expected, int *loss);
 uint32_t mgcp_state_calc_jitter(struct mgcp_rtp_state *);
 
 /* payload processing default functions */
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,
diff --git a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
index f19cb4c97..c5254c158 100644
--- a/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
+++ b/openbsc/src/osmo-bsc_nat/bsc_mgcp_utils.c
@@ -342,7 +342,7 @@ static void remember_pending_dlcx(struct nat_sccp_connection *con, uint32_t tran
 	stats->net_os = endp->net_end.octets;
 	stats->bts_pr = endp->bts_end.packets;
 	stats->bts_or = endp->bts_end.octets;
-	mgcp_state_calc_loss(&endp->bts_state, &endp->bts_end,
+	mgcp_state_calc_loss(&endp->bts_state,
 				&stats->bts_expected, &stats->bts_loss);
 	stats->bts_jitter = mgcp_state_calc_jitter(&endp->bts_state);
 
diff --git a/openbsc/tests/mgcp/mgcp_test.c b/openbsc/tests/mgcp/mgcp_test.c
index b2cb938ce..3a5702b7b 100644
--- a/openbsc/tests/mgcp/mgcp_test.c
+++ b/openbsc/tests/mgcp/mgcp_test.c
@@ -753,8 +753,8 @@ static void test_packet_loss_calc(void)
 		state.stats_max_seq = pl_test_dat[i].max_seq;
 		state.stats_cycles = pl_test_dat[i].cycles;
 
-		rtp.packets = pl_test_dat[i].packets;
-		mgcp_state_calc_loss(&state, &rtp, &expected, &loss);
+		state.stats_packets = pl_test_dat[i].packets;
+		mgcp_state_calc_loss(&state, &expected, &loss);
 
 		if (loss != pl_test_dat[i].loss || expected != pl_test_dat[i].expected) {
 			printf("FAIL: Wrong exp/loss at idx(%d) Loss(%d vs. %d) Exp(%u vs. %u)\n",