Support SDP context over SIP.

Added setup_sdp_transport() to allow higher layer protocols to call SDP with context to correctly setup an OFFER/ANSWER within SDP (which doesn't have its own transport layer).  I attempted to keep backwards compatibility until all higher layer protocols set up OFFER/ANSWER context.  If OFFER/ANSWER (request/response) can't be found (which would be the case for higher layer protocols without context), Wireshark should resort to the old behavior of applying SDP information as it sees packets.

This patch includes integration with SIP as it appears to have the most bug reports.  Other higher layer protocols will be done later.  Most are mentioned in bug 2368.

Fixes bug 2368 (https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=2368) and all its duplicates
Fixes bug 2992 (https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=2992) and all its duplicates

svn path=/trunk/; revision=47564

1 files changed, 44 insertions, 31 deletions

diff --git a/epan/dissectors/packet-sip.c b/epan/dissectors/packet-sip.c
index 1619db612f..190791b38c 100644
--- a/epan/dissectors/packet-sip.c
+++ b/epan/dissectors/packet-sip.c
@@ -55,6 +55,9 @@
 #include "packet-isup.h"
 #include "packet-sip.h"
 
+#include "packet-sdp.h"  /* SDP needs a transport layer to determine request/response */
+
+
 #define TCP_PORT_SIP 5060
 #define UDP_PORT_SIP 5060
 #define TLS_PORT_SIP 5061
@@ -3076,6 +3079,32 @@ dissect_sip_common(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tr
 	col_append_str(pinfo->cinfo, COL_INFO, " | ");
 	col_set_fence(pinfo->cinfo, COL_INFO);
 
+	/* Find the total setup time, Must be done before checking for resend
+	 * As that will overwrite the "Request packet no".
+	 */
+	if ((line_type == REQUEST_LINE)&&(strcmp(cseq_method, "ACK") == 0))
+	{
+		request_for_response = sip_find_invite(pinfo, cseq_method, call_id,
+		                                        cseq_number_set, cseq_number,
+		                                        &response_time);
+		stat_info->setup_time = response_time;
+	}
+
+	/* Check if this packet is a resend. */
+	resend_for_packet = sip_is_packet_resend(pinfo, cseq_method, call_id,
+	                                         cseq_number_set, cseq_number,
+	                                         line_type);
+	/* Mark whether this is a resend for the tap */
+	stat_info->resend = (resend_for_packet > 0);
+
+	/* For responses, try to link back to request frame */
+	if (line_type == STATUS_LINE)
+	{
+		request_for_response = sip_find_request(pinfo, cseq_method, call_id,
+		                                        cseq_number_set, cseq_number,
+		                                        &response_time);
+	}
+
 	if (datalen > 0) {
 		/*
 		 * There's a message body starting at "offset".
@@ -3105,6 +3134,21 @@ dissect_sip_common(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tr
 		if ( media_type_str_lower_case != NULL ) {
 			void *save_private_data = pinfo->private_data;
 			pinfo->private_data = content_type_parameter_str;
+
+			/* SDP needs a transport layer to determine request/response */
+			if (!strcmp(media_type_str_lower_case, "application/sdp")) {
+				/* Resends don't count */
+				if (resend_for_packet == 0) {
+					if (line_type == REQUEST_LINE) {
+						setup_sdp_transport(next_tvb, pinfo, SDP_EXCHANGE_OFFER, pinfo->fd->num);
+					} else if (line_type == STATUS_LINE) {
+						setup_sdp_transport(next_tvb, pinfo, 
+							(stat_info->response_code == 200) ? SDP_EXCHANGE_ANSWER_ACCEPT : SDP_EXCHANGE_ANSWER_REJECT, 
+							request_for_response);
+					}
+				}
+			}
+
 			found_match = dissector_try_string(media_type_dissector_table,
 			                                   media_type_str_lower_case,
 			                                   next_tvb, pinfo,
@@ -3140,25 +3184,6 @@ dissect_sip_common(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tr
 		offset += datalen;
 	}
 
-
-	/* Find the total setup time, Must be done before checking for resend
-	 * As that will overwrite the "Request packet no".
-	 */
-	if ((line_type == REQUEST_LINE)&&(strcmp(cseq_method, "ACK") == 0))
-	{
-		request_for_response = sip_find_invite(pinfo, cseq_method, call_id,
-		                                        cseq_number_set, cseq_number,
-		                                        &response_time);
-		stat_info->setup_time = response_time;
-	}
-
-	/* Check if this packet is a resend. */
-	resend_for_packet = sip_is_packet_resend(pinfo, cseq_method, call_id,
-	                                         cseq_number_set, cseq_number,
-	                                         line_type);
-	/* Mark whether this is a resend for the tap */
-	stat_info->resend = (resend_for_packet > 0);
-
 	/* And add the filterable field to the request/response line */
 	if (reqresp_tree)
 	{
@@ -3172,19 +3197,7 @@ dissect_sip_common(tvbuff_t *tvb, int offset, packet_info *pinfo, proto_tree *tr
 			                           tvb, orig_offset, 0, resend_for_packet);
 			PROTO_ITEM_SET_GENERATED(item);
 		}
-	}
-
-	/* For responses, try to link back to request frame */
-	if (line_type == STATUS_LINE)
-	{
-		request_for_response = sip_find_request(pinfo, cseq_method, call_id,
-		                                        cseq_number_set, cseq_number,
-		                                        &response_time);
-	}
 
-	if (reqresp_tree)
-	{
-		proto_item *item;
 		if (request_for_response > 0)
 		{
 			item = proto_tree_add_uint(reqresp_tree, hf_sip_matching_request_frame,