https://bugs.wireshark.org/bugzilla/show_bug.cgi?id=6787
--- Comment #14 from Bill Meier <wmeier@xxxxxxxxxxx> 2012-07-26 14:23:29 PDT ---
FF:
There are two cases (see below) wherein the dissector does a 'return 0' which
seem incorrect to me. (The 3rd case of 'return 0' is redundant).
packet-mpls.c treats a return value of 0 as "not dissected" (not found ?)
and then continues with other tries at dissection.
However, packet-mpls-y1711.c acts as "found" even though doing a 'return 0'.
That is, data is added either to the info column or to the tree and thus,
presumably, packet-mpls need not continue to try to dissect.
(Not the most earthshaking issue), but what do you think ? (See below for my
suggested changes).
The existing code;
if (!tree) {
if (check_col(pinfo->cinfo, COL_INFO)) {
if (tvb_bytes_exist(tvb, offset, 1)) {
functype = tvb_get_guint8(tvb, offset);
col_append_fstr(pinfo->cinfo, COL_INFO, " (Y.1711: %s)",
(functype == 0x01) ? "CV" :
(functype == 0x02) ? "FDI" :
(functype == 0x03) ? "BDI" :
(functype == 0x07) ? "FDD" :
"reserved/unknown");
}
}
return 0;
}
/* sanity checks */
if (!tvb_bytes_exist(tvb, offset, 44)) {
/*
* ITU-T Y.1711, 5.3: PDUs must have a minimum payload length of
* 44 bytes
*/
proto_tree_add_text(tree, tvb, offset, -1,
"Error: must have a minimum payload "
"length of 44 bytes");
return 0;
}
==============
I would be inclined to do something the following:
functype = tvb_get_guint8(tvb, offset); // will do bounds error if no data
col_append_fstr(pinfo->cinfo, COL_INFO, " (Y.1711: %s)",
(functype == 0x01) ? "CV" :
(functype == 0x02) ? "FDI" :
(functype == 0x03) ? "BDI" :
(functype == 0x07) ? "FDD" :
"reserved/unknown");
/* sanity checks */
if (tvb_reported_length(tvb) < 44)) {
/*
* ITU-T Y.1711, 5.3: PDUs must have a minimum payload length of
* 44 bytes
*/
proto_tree_add_text(tree, tvb, offset, -1,
"Error: must have a minimum payload "
"length of 44 bytes");
<call the data dissector to display (some of) the bytes>
return tvb_reported_length(tvb);
}
if (!tree)
return
...
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