SDP/RTP: Support for "bundled" media.

Modern SDP usage (e.g. SIP, WebRTC) can "bundle" multiple RTP media streams on
a single port. Thus the RTP dissector has to be able to handle audio and video
at the same time, so the gboolean flag in _rtp_info was changed to a bit mask.
The SDP parsing was then changed to detect multiple "m=" lines using the same
port, and combine their audio/video bit masks, and the rtp_dyn_payload used
has all the audio and video payload descriptions.

Change-Id: Ifa3c034260f892ed005fe28647d28f3b0b1b05cf
Reviewed-on: https://code.wireshark.org/review/25431
Petri-Dish: Jaap Keuter <jaap.keuter@xs4all.nl>
Tested-by: Petri Dish Buildbot
Reviewed-by: Anders Broman <a.broman58@gmail.com>

1 files changed, 59 insertions, 7 deletions

diff --git a/epan/dissectors/packet-sdp.c b/epan/dissectors/packet-sdp.c
index 1a3e2cc1eb..928a5d02c2 100644
--- a/epan/dissectors/packet-sdp.c
+++ b/epan/dissectors/packet-sdp.c
@@ -248,7 +248,8 @@ typedef struct {
  */
 typedef struct {
     transport_proto_t proto;    /**< Protocol, parsed from "m=" line. */
-    gboolean is_video;          /**< Whether "m=video" */
+    guint32 media_types;        /**< Whether "m=video" or others */
+    gboolean bundled;           /**< "m=" lines are "bundled", that is, all on same port */
     guint16 media_port;         /**< Port number, parsed from "m=" line. */
     guint16 control_port;       /**< Port number, parsed from "a=rtcp" or "a=rtcp-mux" line. */
     address conn_addr;          /**< The address from the "c=" line (default
@@ -1026,7 +1027,12 @@ dissect_sdp_media(tvbuff_t *tvb, packet_info* pinfo, proto_item *ti,
                         ENC_UTF_8|ENC_NA, wmem_packet_scope(), &media_type_str);
     if (media_desc) {
         /* for RTP statistics (supposedly?) */
-        media_desc->is_video = strcmp(media_type_str, "video") == 0;
+        if (strcmp(media_type_str, "audio") == 0)
+            media_desc->media_types |= RTP_MEDIA_AUDIO;
+        else if (strcmp(media_type_str, "video") == 0)
+            media_desc->media_types |= RTP_MEDIA_VIDEO;
+        else
+            media_desc->media_types |= RTP_MEDIA_OTHER;
     }
     DPRINT(("parsed media_type=%s", media_type_str));
 
@@ -2101,16 +2107,52 @@ complete_descriptions(transport_info_t *transport_info, guint answer_offset)
 {
     guint media_count = wmem_array_get_count(transport_info->media_descriptions);
     media_description_t *media_descs = (media_description_t *)wmem_array_get_raw(transport_info->media_descriptions);
+    media_description_t *bundle_media_desc = NULL;
 
     DPRINT(("complete_descriptions called with answer_offset=%d media_count=%d",
             answer_offset, media_count));
 
+    for (guint i = answer_offset; i < media_count && !bundle_media_desc; i++) {
+        for (guint j = i+1; j < media_count && !bundle_media_desc; j++) {
+            if (media_descs[i].media_port == media_descs[j].media_port)
+                bundle_media_desc = &media_descs[i];
+        }
+    }
+
+    if (bundle_media_desc) {
+        /* We have "bundling" of media, so now combine all the media bit masks
+           and merge the rtp_dyn_payload so that the first media description
+           has all the data for every media desciption. */
+        for (guint i = answer_offset; i < media_count; i++) {
+            media_description_t *media_desc = &media_descs[i];
+
+            if (bundle_media_desc->media_port == media_desc->media_port) {
+                media_desc->bundled = TRUE;
+
+                if (media_desc != bundle_media_desc) {
+                    bundle_media_desc->media_types |= media_desc->media_types;
+                    for (guint pt = 0; pt < 128; ++pt) {
+                        const char * encoding_name;
+                        int sample_rate;
+                        if (rtp_dyn_payload_get_full(media_desc->media.rtp_dyn_payload,
+                                                     pt, &encoding_name, &sample_rate))
+                            rtp_dyn_payload_insert(bundle_media_desc->media.rtp_dyn_payload,
+                                                   pt, encoding_name, sample_rate);
+                    }
+                }
+            }
+        }
+    }
+
     for (guint i = answer_offset; i < media_count; i++) {
         media_description_t *media_desc = &media_descs[i];
 
         if (media_desc->control_port == 0)
             media_desc->control_port = media_desc->media_port + 1;
 
+        if (media_desc->control_port == 0)
+            media_desc->control_port = media_desc->media_port + 1;
+
         /* If this is an answer to a previous offer... */
         if (answer_offset > 0) {
             /* A zero port removes the media stream (RFC 3264, Section 8.2) */
@@ -2169,6 +2211,8 @@ apply_sdp_transport(packet_info *pinfo, transport_info_t *transport_info, int re
         establish_frame = request_frame;
     }
 
+    gboolean bundled_media_set = FALSE;
+
     for (guint i = 0; i < wmem_array_get_count(transport_info->media_descriptions); i++) {
         media_description_t *media_desc =
             (media_description_t *)wmem_array_index(transport_info->media_descriptions, i);
@@ -2176,11 +2220,20 @@ apply_sdp_transport(packet_info *pinfo, transport_info_t *transport_info, int re
 
         /* Add (s)rtp and (s)rtcp conversation, if available (overrides t38 if conversation already set) */
         if ((media_desc->media_port != 0) &&
+            !media_desc->media.set_rtp &&
             (media_desc->proto == SDP_PROTO_RTP ||
              media_desc->proto == SDP_PROTO_SRTP) &&
             (media_desc->conn_addr.type == AT_IPv4 ||
              media_desc->conn_addr.type == AT_IPv6)) {
 
+            media_desc->media.set_rtp = TRUE;
+
+            if (media_desc->bundled) {
+                if (bundled_media_set)
+                    continue;
+                bundled_media_set = TRUE;
+            }
+
             if (media_desc->proto == SDP_PROTO_SRTP) {
                 srtp_info = wmem_new0(wmem_file_scope(), struct srtp_info);
                 if (transport_info->encryption_algorithm != SRTP_ENC_ALG_NOT_SET) {
@@ -2196,7 +2249,7 @@ apply_sdp_transport(packet_info *pinfo, transport_info_t *transport_info, int re
                 /* srtp_add_address and rtp_add_address are given the request_frame's not this frame's number,
                    because that's where the RTP flow started, and thus conversation needs to check against */
                 srtp_add_address(pinfo, PT_UDP, &media_desc->conn_addr, media_desc->media_port, 0, "SDP", establish_frame,
-                                 media_desc->is_video,
+                                 media_desc->media_types,
                                  media_desc->media.rtp_dyn_payload, srtp_info);
                 DENDENT();
             } else {
@@ -2204,23 +2257,22 @@ apply_sdp_transport(packet_info *pinfo, transport_info_t *transport_info, int re
                         i, media_desc->media_port));
                 DINDENT();
                 rtp_add_address(pinfo, PT_UDP, &media_desc->conn_addr, media_desc->media_port, 0, "SDP", establish_frame,
-                                media_desc->is_video,
+                                media_desc->media_types,
                                 media_desc->media.rtp_dyn_payload);
                 DENDENT();
             }
-            media_desc->media.set_rtp = TRUE;
             /* SPRT might use the same port... */
             current_rtp_port = media_desc->media_port;
 
             if (rtcp_handle && media_desc->media_port != media_desc->control_port) {
                 if (media_desc->proto == SDP_PROTO_SRTP) {
-                    DPRINT(("calling rtcp_add_address, channel=%d, media_port=%d",
+                    DPRINT(("calling rtcp_add_address, channel=%d, control_port=%d",
                             i, media_desc->control_port));
                     DINDENT();
                     srtcp_add_address(pinfo, &media_desc->conn_addr, media_desc->control_port, 0, "SDP", establish_frame, srtp_info);
                     DENDENT();
                  } else {
-                    DPRINT(("calling rtcp_add_address, channel=%d, media_port=%d",
+                    DPRINT(("calling rtcp_add_address, channel=%d, control_port=%d",
                             i, media_desc->control_port));
                     DINDENT();
                     rtcp_add_address(pinfo, &media_desc->conn_addr, media_desc->control_port, 0, "SDP", establish_frame);