Are there any other dissectors that invoke another dissector like what I am
trying to do that I can use as an example?
TIA,
Jon
On Friday 07 January 2005 02:36 pm, Jon Ringle wrote:
> Hello,
>
> I am currently developing an ICE implementation
> (http://www.ietf.org/internet-drafts/draft-ietf-mmusic-ice-03.txt). ICE
> uses STUN on the same port that the RTP media is sent on. The ICE
> application demultiplexes STUN/RTP by looking at the first 2 bits of the
> UDP packet. RTP will have 0b10 (rtp.version == 2) and a STUN packet will
> have 0b00. I would like to have ethereal dissect what looks like a
> rtp.version == 0 packet as a STUN packet.
>
> I found in epan/dissectors/packet-rtp.c:dissect_rtp_heur() a check to
> validate that rtp.version == 2. I would like to modify this routine to call
> the STUN dissector, but I'm not sure how to make this call:
>
> static gboolean
> dissect_rtp_heur( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
> {
> guint8 octet1, octet2;
> unsigned int version;
> unsigned int payload_type;
> unsigned int offset = 0;
>
> /* This is a heuristic dissector, which means we get all the UDP
> * traffic not sent to a known dissector and not claimed by
> * a heuristic dissector called before us!
> */
>
> if (! global_rtp_heur)
> return FALSE;
>
> /* Get the fields in the first octet */
> octet1 = tvb_get_guint8( tvb, offset );
> version = RTP_VERSION( octet1 );
>
> if (version == 0) {
> /******************************************/
> /* Call the STUN dissector here, but how? */
> /******************************************/
> return TRUE;
> } else if (version != 2) {
> /* Unknown or unsupported version */
> return FALSE;
> }
>
> /* Get the fields in the second octet */
> octet2 = tvb_get_guint8( tvb, offset + 1 );
> payload_type = RTP_PAYLOAD_TYPE( octet2 );
> /* if (payload_type == PT_PCMU ||
> * payload_type == PT_PCMA)
> * payload_type == PT_G729)
> * */
> if (payload_type <= PT_H263) {
> dissect_rtp( tvb, pinfo, tree );
> return TRUE;
> }
> else {
> return FALSE;
> }
> }
>
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