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In the "PPP in HDLC-Like Framing" items, consider the starting delimiter 

part of the packet's data.

If a packet has a starting and ending frame delimiter - i.e., the
delimiter at the end is followed by another delimiter - consider the
ending delimiter part of the first packet's raw data.

svn path=/trunk/; revision=12749
This commit is contained in:
Guy Harris 2004-12-14 08:15:13 +00:00
parent 6ced79161a
commit 21a206c37f
1 changed files with 32 additions and 5 deletions
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37
epan/dissectors/packet-ppp.c
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@ -3246,8 +3246,8 @@ dissect_ppp_raw_hdlc( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
{
proto_item *ti;
proto_tree *bs_tree = NULL;
gint offset, end_offset;
int length;
gint offset, end_offset, data_offset;
int length, data_length;
tvbuff_t *ppp_tvb;
gboolean first = TRUE;
@ -3332,18 +3332,45 @@ dissect_ppp_raw_hdlc( tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree )
}
return;
}
data_offset = offset+1; /* skip starting frame delimiter */
data_length = end_offset - data_offset;
/*
* Is that frame delimiter immediately followed by another one?
* Some PPP implementations put a frame delimiter at the
* beginning and the end of each frame, although RFC 1662
* appears only to require that there be one frame delimiter
* between adjacent frames:
*
* Each frame begins and ends with a Flag Sequence, which is the
* binary sequence 01111110 (hexadecimal 0x7e). All implementations
* continuously check for this flag, which is used for frame
* synchronization.
*
* Only one Flag Sequence is required between two frames. Two
* consecutive Flag Sequences constitute an empty frame, which is
* silently discarded, and not counted as a FCS error.
*
* If the delimiter at the end of this frame is followed by
* another delimiter, we consider the first delimiter part
* of this frame.
*/
if (tvb_offset_exists(tvb, end_offset+1) &&
tvb_get_guint8(tvb, end_offset+1) == 0x7e)
end_offset++;
length = end_offset - offset;
if (tree)
proto_tree_add_text(bs_tree, tvb, offset+1, length-1, "PPP Data");
proto_tree_add_text(bs_tree, tvb, offset, length, "PPP Data");
if (length > 1) {
ppp_tvb = remove_escape_chars(tvb, offset + 1, length - 1);
ppp_tvb = remove_escape_chars(tvb, data_offset, data_length);
if (ppp_tvb != NULL) {
add_new_data_source(pinfo, ppp_tvb, "PPP Message");
dissect_ppp_hdlc_common(ppp_tvb, pinfo, tree);
first = FALSE;
}
}
offset = end_offset+1;/* +1 Takes us past the end delimiter */
offset = end_offset;
} /* end while */
}