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Clean up indentation. 

Do more length checks, so we reject trailers that have nothing to
dissect.

Test for the trailer length being >= 8, rather than for having the 0x08
bit set (they amount to the same thing, as the trailer length is <= 14,
and >= 8 is what we really want if we're checking whether there's a
timestamp).

svn path=/trunk/; revision=40142
This commit is contained in:
Guy Harris 2011-12-10 05:29:09 +00:00
parent d2f9204568
commit 3fc0968b02
1 changed files with 22 additions and 4 deletions
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26
epan/dissectors/packet-vssmonitoring.c
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@ -64,7 +64,7 @@ static gboolean vssmonitoring_use_heuristics = TRUE;
static int
dissect_vssmonitoring(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
{
proto_tree *ti = NULL;
proto_tree *ti = NULL;
proto_tree *vssmonitoring_tree = NULL;
guint offset = 0;
@ -84,7 +84,19 @@ dissect_vssmonitoring(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
* port stamp (1 or 2 bytes)
* fcs (4 bytes)
*
* This means a trailer length must not be more than 14 bytes
* The FCS is dissected by our caller, so we check for a trailer
* with a length that includes one or more of a time stamp and
* a 1-byte or 2-byte port stamp.
*
* This means a trailer length must not be more than 14 bytes,
* and:
*
* must not be 3 modulo 3 (as it can't have both a 1-byte
* and a 2-byte port stamp);
*
* if it's less than 8 bytes, must not be 0 modulo 3 (as
* it must have a 1-byte or 2-byte port stamp, given that
* it has no timestamp).
*/
if ( trailer_len > 14 )
return 0;
@ -95,7 +107,13 @@ dissect_vssmonitoring(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
if ( (trailer_len & 3) == 3 )
return 0;
if ( trailer_len & 8 ) {
/* ... and if you have neither a time stamp nor a port stamp,
* you don't have a trailer
*/
if ( (trailer_len & 3) == 0 && trailer_len < 8 )
return 0;
if ( trailer_len >= 8 ) {
vssmonitoring_time.secs = tvb_get_ntohl(tvb, offset);
vssmonitoring_time.nsecs = tvb_get_ntohl(tvb, offset + 4);
vssmonitoring_clksrc = (guint8)(((guint32)vssmonitoring_time.nsecs) >> CLKSRC_SHIFT);
@ -137,7 +155,7 @@ dissect_vssmonitoring(tvbuff_t *tvb, packet_info *pinfo, proto_tree *tree)
}
/* Do we have a timestamp? */
if ( trailer_len & 8 ) {
if ( trailer_len >= 8 ) {
if (tree) {
proto_tree_add_time(vssmonitoring_tree, hf_vssmonitoring_time, tvb, offset, 8, &vssmonitoring_time);
proto_tree_add_uint(vssmonitoring_tree, hf_vssmonitoring_clksrc, tvb, offset + 4, 1, vssmonitoring_clksrc);