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TCP: Follow: Don't treat placeholder value 0 as a real ACK number 

Since the wraparound aware GT_SEQ is used, passing in 0 for the
ACK number can result in thinking that bytes are missing and
dropping frames from the follow stream tap.
This commit is contained in:
John Thacker 2021-10-11 20:38:02 -04:00 committed by Wireshark GitLab Utility
parent f6b0de6b12
commit 634650f1e4
1 changed files with 4 additions and 4 deletions
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8
epan/dissectors/packet-tcp.c
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@ -1049,7 +1049,7 @@ typedef struct tcp_follow_tap_data
* missing segments before them).
*/
static gboolean
check_follow_fragments(follow_info_t *follow_info, gboolean is_server, guint32 acknowledged, guint32 packet_num)
check_follow_fragments(follow_info_t *follow_info, gboolean is_server, guint32 acknowledged, guint32 packet_num, gboolean use_ack)
{
GList *fragment_entry;
follow_record_t *fragment, *follow_record;
@ -1127,7 +1127,7 @@ check_follow_fragments(follow_info_t *follow_info, gboolean is_server, guint32 a
}
}
if( GT_SEQ(acknowledged, lowest_seq) ) {
if( use_ack && GT_SEQ(acknowledged, lowest_seq) ) {
/* There are frames missing in the capture file that were seen
* by the receiving host. Add dummy stream chunk with the data
* "[xxx bytes missing in capture file]".
@ -1185,7 +1185,7 @@ follow_tcp_tap_listener(void *tapdata, packet_info *pinfo,
* seen by the receiving host (Fixes bug 592).
*/
if (follow_info->fragments[!is_server] != NULL) {
while (check_follow_fragments(follow_info, !is_server, follow_data->tcph->th_ack, pinfo->fd->num));
while (check_follow_fragments(follow_info, !is_server, follow_data->tcph->th_ack, pinfo->fd->num, TRUE));
}
/*
@ -1240,7 +1240,7 @@ follow_tcp_tap_listener(void *tapdata, packet_info *pinfo,
follow_info->payload = g_list_prepend(follow_info->payload, follow_record);
/* done with the packet, see if it caused a fragment to fit */
while(check_follow_fragments(follow_info, is_server, 0, pinfo->fd->num));
while(check_follow_fragments(follow_info, is_server, 0, pinfo->fd->num, FALSE));
} else {
/* Out of order packet (more preceding segments are expected). */
follow_info->fragments[is_server] = g_list_append(follow_info->fragments[is_server], follow_record);