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From Peter Kjellerstedt: 

I was capturing an RTP stream the other day which contained JPEG images
streamed according to RFC 2435. However, Wireshark reported them as malformed.
After some debugging of the Wireshark code it turned out that the decoding of
JPEG images which contain a quantization table was incorrect. I have attached a
patch to correct the decoding.

svn path=/trunk/; revision=24246
This commit is contained in:
Jaap Keuter 2008-02-02 16:41:12 +00:00
parent 1a9aa1ae62
commit 1c2f043913
1 changed files with 9 additions and 7 deletions
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16
epan/dissectors/packet-jpeg.c
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@ -77,6 +77,7 @@ dissect_jpeg( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
proto_tree *main_hdr_tree = NULL;
proto_tree *restart_hdr_tree = NULL;
proto_tree *qtable_hdr_tree = NULL;
guint32 fragment_offset = 0;
guint16 len = 0;
guint8 type = 0;
guint8 q = 0;
@ -103,6 +104,7 @@ dissect_jpeg( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
proto_tree_add_item(main_hdr_tree, hf_rtp_jpeg_main_hdr_ts, tvb, offset, 1, FALSE);
offset += 1;
proto_tree_add_item(main_hdr_tree, hf_rtp_jpeg_main_hdr_offs, tvb, offset, 3, FALSE);
fragment_offset = tvb_get_ntoh24(tvb, offset);
offset += 3;
proto_tree_add_item(main_hdr_tree, hf_rtp_jpeg_main_hdr_type, tvb, offset, 1, FALSE);
type = tvb_get_guint8(tvb, offset);
@ -128,19 +130,19 @@ dissect_jpeg( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
offset += 2;
}
if (q >= 128) {
if (q >= 128 && fragment_offset == 0) {
ti = proto_tree_add_item(jpeg_tree, hf_rtp_jpeg_qtable_hdr, tvb, offset, -1, FALSE);
qtable_hdr_tree = proto_item_add_subtree(ti, ett_jpeg);
proto_tree_add_item(main_hdr_tree, hf_rtp_jpeg_qtable_hdr_mbz, tvb, offset, 1, FALSE);
proto_tree_add_item(qtable_hdr_tree, hf_rtp_jpeg_qtable_hdr_mbz, tvb, offset, 1, FALSE);
offset += 1;
proto_tree_add_item(main_hdr_tree, hf_rtp_jpeg_qtable_hdr_prec, tvb, offset, 1, FALSE);
proto_tree_add_item(qtable_hdr_tree, hf_rtp_jpeg_qtable_hdr_prec, tvb, offset, 1, FALSE);
offset += 1;
proto_tree_add_item(main_hdr_tree, hf_rtp_jpeg_qtable_hdr_length, tvb, offset, 2, FALSE);
len = tvb_get_letohs(tvb, offset);
proto_tree_add_item(qtable_hdr_tree, hf_rtp_jpeg_qtable_hdr_length, tvb, offset, 2, FALSE);
len = tvb_get_ntohs(tvb, offset);
offset += 2;
if (len > 0) {
proto_tree_add_item(main_hdr_tree, hf_rtp_jpeg_qtable_hdr_data, tvb, offset, len, FALSE);
offset += 1;
proto_tree_add_item(qtable_hdr_tree, hf_rtp_jpeg_qtable_hdr_data, tvb, offset, len, FALSE);
offset += len;
}
proto_item_set_len(ti, len + 4);
}