mgcp: Work on the decompress, compress...

3 files changed, 117 insertions, 3 deletions

diff --git a/openbsc/include/openbsc/mgcp_internal.h b/openbsc/include/openbsc/mgcp_internal.h
index dc00112d3..c1b2bb338 100644
--- a/openbsc/include/openbsc/mgcp_internal.h
+++ b/openbsc/include/openbsc/mgcp_internal.h
@@ -175,7 +175,7 @@ struct mgcp_trunk_config *mgcp_trunk_num(struct mgcp_config *cfg, int index);
 
 int rtp_compress(struct mgcp_rtp_compr_state *state, struct msgb *msg,
 		 int endpoint, struct llist_head *rtp_packets);
-struct llist_head rtp_decompress(struct mgcp_rtp_compr_state *state, void *ctx,
+struct llist_head rtp_decompress(struct mgcp_rtp_compr_state *state,
 				  struct msgb *msg);
 
 
diff --git a/openbsc/src/libmgcp/rtp_helper.c b/openbsc/src/libmgcp/rtp_helper.c
index 77fc4c819..66687b19b 100644
--- a/openbsc/src/libmgcp/rtp_helper.c
+++ b/openbsc/src/libmgcp/rtp_helper.c
@@ -44,6 +44,29 @@ struct reduced_rtp_hdr {
 #define msgb_put_struct(msg, str) \
 	(str *) msgb_put(msg, sizeof(str))
 
+
+static void fill_rtp_hdr(struct rtp_hdr *hdr)
+{
+	hdr->csrc_count = 0;
+	hdr->extension = 0;
+	hdr->padding = 0;
+	hdr->version = RTP_VERSION;
+
+	/* detect stop of silence? */
+	hdr->marker = 0;
+	hdr->payload_type = 98;
+}
+
+static void fill_rtp_state(struct rtp_hdr *hdr,
+			   struct mgcp_rtp_compr_state *state)
+{
+	hdr->ssrc = htonl(state->generated_ssrc);
+	hdr->sequence = htons(state->sequence++);
+	hdr->timestamp = htonl(state->timestamp);
+	state->timestamp += 160;
+}
+			   
+
 /**
  * I try to compress these packets into one single stream. I have various
  * limitations. I do not support packets that jump backwards, the rtp_packets
@@ -82,6 +105,15 @@ int rtp_compress(struct mgcp_rtp_compr_state *state, struct msgb *msg,
 			continue;
 		}
 
+		if (msgb_l2len(rtp) < sizeof(struct rtp_hdr) + 17) {
+			LOGP(DMGCP, LOGL_ERROR,
+			     "We assume every payload is 17 byte: %d\n",
+			     msgb_l2len(rtp) - sizeof(struct rtp_hdr));
+			llist_del(&rtp->list);
+			talloc_free(rtp);
+			continue;
+		}
+
 		hdr = (struct rtp_hdr *) rtp->l2h;
 		sequence = ntohs(hdr->sequence);
 		if (sequence < last_sequence && sequence != 0) {
@@ -120,11 +152,49 @@ int rtp_compress(struct mgcp_rtp_compr_state *state, struct msgb *msg,
 	return count;
 }
 
-struct llist_head rtp_decompress(struct mgcp_rtp_compr_state *state, void *ctx,
+struct llist_head rtp_decompress(struct mgcp_rtp_compr_state *state,
 				  struct msgb *msg)
 {
+	struct reduced_rtp_hdr *rhdr;
+	int i;
 	struct llist_head list;
 	INIT_LLIST_HEAD(&list);
 
+	if (msgb_l2len(msg) < sizeof(*rhdr)) {
+		LOGP(DMGCP, LOGL_ERROR, "Compressed header does not fit.\n");
+		return list;
+	}
+
+	rhdr = (struct reduced_rtp_hdr *) msg->l2h;
+	if (rhdr->type != 0) {
+		LOGP(DMGCP, LOGL_ERROR,
+		     "Type %d is not known.\n", rhdr->type);
+		return list;
+	}
+
+	if (msgb_l2len(msg) < sizeof(*rhdr) + rhdr->payloads * 17) {
+		LOGP(DMGCP, LOGL_ERROR,
+		     "Payloads do not fit. %d\n", rhdr->payloads);
+		return list;
+	}
+
+	for (i = 0; i < rhdr->payloads; ++i) {
+		struct rtp_hdr *hdr;
+		struct msgb *out = msgb_alloc_headroom(4096, 128, "RTP decompr");
+		if (!out) {
+			LOGP(DMGCP, LOGL_ERROR, "Failed to allocate: %d\n", i);
+			continue;
+		}
+
+		out->l2h = msgb_put(out, 0);
+		hdr = msgb_put_struct(out, struct rtp_hdr);
+		fill_rtp_hdr(hdr);
+		fill_rtp_state(hdr, state);
+
+		out->l3h = msgb_put(out, 17);
+		memcpy(out->l3h, &rhdr->data[i * 17], 17);
+		msgb_enqueue(&list, out);
+	}
+
 	return list;
 }
diff --git a/openbsc/tests/mgcp/mgcp_test.c b/openbsc/tests/mgcp/mgcp_test.c
index 8c4ee84d0..30bc625c0 100644
--- a/openbsc/tests/mgcp/mgcp_test.c
+++ b/openbsc/tests/mgcp/mgcp_test.c
@@ -121,6 +121,9 @@ static struct msgb *from(const uint8_t *data, uint16_t len)
 
 void test_compress()
 {
+	int i = 0;
+	struct msgb *msg;
+
 	struct msgb *msg1 = FROM(packet_1);
 	struct msgb *msg2 = FROM(packet_2);
 	struct msgb *msg3 = FROM(packet_3);
@@ -136,6 +139,9 @@ void test_compress()
 	struct mgcp_rtp_compr_state state;
 	memset(&state, 0, sizeof(state));
 	state.last_ts = UCHAR_MAX;
+	state.generated_ssrc = 0x6f0fb1da;
+	state.sequence = 52103;
+	state.timestamp = 4157323848u;
 
 	struct msgb *out = msgb_alloc_headroom(4096, 128, "out");
 	out->l2h = msgb_put(out, 0);
@@ -154,7 +160,45 @@ void test_compress()
 	printf("output is: %s\n", osmo_hexdump(out->l2h, msgb_l2len(out)));
 
 
-	list = rtp_decompress(&state, NULL, out);
+	list = rtp_decompress(&state, out);
+
+	llist_for_each_entry(msg, &list, list) {
+		const uint8_t *data;
+		int len;
+
+		switch (++i) {
+		case 1:
+			data = packet_1;
+			len = sizeof(packet_1);
+			break;
+		case 2:
+			data = packet_2;
+			len = sizeof(packet_2);
+			break;
+		case 3:
+			data = packet_3;
+			len = sizeof(packet_3);
+			break;
+		case 4:
+			data = packet_4;
+			len = sizeof(packet_4);
+			break;
+		default:
+			fprintf(stderr, "Should not be reached.\n");
+			abort();
+		}
+
+		if (msgb_l2len(msg) != len) {
+			fprintf(stderr, "Wrong len for %d %d\n", i, msgb_l2len(msg));
+			abort();
+		}
+
+		if (memcmp(msg->l2h, data, len) != 0) {
+			fprintf(stderr, "Wrong data for %d, '%s'\n",
+				i, osmo_hexdump(msg->l2h, msgb_l2len(msg)));
+			abort();
+		}
+	}
 
 	msgb_free(out);
 }