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From Martin Mathieson: 

- while parsing fmtp lines, the dissector looks for the MPEG4 'profile-level-id' parameter.  If there is no '=' present, it was throwing an exception and the frame marked as malformed (see e.g. the attached
capture)
- I've added a few comments where the code wasn't obvious to me...

svn path=/trunk/; revision=18332
This commit is contained in:
Anders Broman 2006-06-03 11:48:27 +00:00
parent d72e2d6f6c
commit 5f6f853d16
1 changed files with 37 additions and 4 deletions
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41
epan/dissectors/packet-sdp.c
View File

@ -1073,9 +1073,11 @@ static const value_string mpeg4es_level_indication_vals[] =
{ 0xff, "Reserved for Escape" },
{ 0, NULL },
};
/*
* TODO: Make this a more generic routine to dissect fmtp parameters depending on media types
*/
static void
decode_sdp_fmtp(proto_tree *tree, tvbuff_t *tvb,gint offset, gint tokenlen, guint8 *mime_type){
decode_sdp_fmtp(proto_tree *tree, tvbuff_t *tvb, gint offset, gint tokenlen, guint8 *mime_type){
gint next_offset;
gint end_offset;
guint8 *field_name;
@ -1083,13 +1085,23 @@ decode_sdp_fmtp(proto_tree *tree, tvbuff_t *tvb,gint offset, gint tokenlen, guin
proto_item *item;
end_offset = offset + tokenlen;
/* Look for an '=' within this value - this may indicate that there is a
profile-level-id parameter to find if the MPEG4 media type is in use */
next_offset = tvb_find_guint8(tvb,offset,-1,'=');
if (next_offset == -1)
{
/* Give up (and avoid exception) if '=' not found */
return;
}
/* Find the name of the parameter */
tokenlen = next_offset - offset;
field_name = tvb_get_ephemeral_string(tvb, offset, tokenlen);
offset = next_offset;
/* Dissect the MPEG4 profile-level-id parameter if present */
if (mime_type != NULL && strcmp(mime_type, "MP4V-ES") == 0) {
if (strcmp(field_name, "profile-level-id") == 0) {
offset++;
@ -1099,6 +1111,20 @@ decode_sdp_fmtp(proto_tree *tree, tvbuff_t *tvb,gint offset, gint tokenlen, guin
PROTO_ITEM_SET_GENERATED(item);
}
}
#if 0
/* TODO: Add code to dissect H264 fmtp parameters wehen an example can be found */
if (mime_type != NULL && strcmp(mime_type, "H264") == 0) {
if (strcmp(field_name, "profile-level-id") == 0) {
char **endptr;
offset++;
tokenlen = end_offset - offset;
format_specific_parameter = tvb_get_ephemeral_string(tvb, offset, tokenlen);
proto_tree_add_text(tree, tvb, offset, tokenlen,
"Test %u", strtoul(format_specific_parameter, endptr, 16));
}
}
#endif
}
static void dissect_sdp_media_attribute(tvbuff_t *tvb, proto_item * ti, transport_info_t *transport_info){
@ -1219,10 +1245,11 @@ static void dissect_sdp_media_attribute(tvbuff_t *tvb, proto_item * ti, transpor
tokenlen = next_offset - offset;
/* Media format extends to the next space */
media_format_item = proto_tree_add_item(sdp_media_attribute_tree,
hf_media_format, tvb, offset,
tokenlen, FALSE);
/* Append encoding name to format if known */
if (transport_info->encoding_name)
proto_item_append_text(media_format_item, " [%s]",
transport_info->encoding_name);
@ -1231,9 +1258,13 @@ static void dissect_sdp_media_attribute(tvbuff_t *tvb, proto_item * ti, transpor
offset = next_offset + 1;
/* There may be 2 parameters given
* TODO: Handle arbitarry number of parameters.
*/
next_offset = tvb_find_guint8(tvb,offset,-1,';');
if(next_offset != -1){
/* There are 2 - add the first parameter */
tokenlen = next_offset - offset;
fmtp_item = proto_tree_add_item(sdp_media_attribute_tree,
hf_media_format_specific_parameter, tvb,
@ -1247,6 +1278,7 @@ static void dissect_sdp_media_attribute(tvbuff_t *tvb, proto_item * ti, transpor
offset = next_offset + 1;
}
/* Now add remaining (or only) parameter */
tokenlen = tvb_find_line_end(tvb, offset, -1, &next_offset, FALSE);
fmtp_item = proto_tree_add_item(sdp_media_attribute_tree,
@ -1260,6 +1292,7 @@ static void dissect_sdp_media_attribute(tvbuff_t *tvb, proto_item * ti, transpor
return;
}
/* No special treatment for values of this attribute type, just add as one item. */
proto_tree_add_item(sdp_media_attribute_tree, hf_media_attribute_value,
tvb, offset, -1, FALSE);
}