forked from osmocom/wireshark
cae5293711
- Don't do '<gulongvar>-<gulongvar> > 0' as it will always be true :-) - Handle the case where a segment is partially retransmitted svn path=/trunk/; revision=25289
433 lines
12 KiB
C
433 lines
12 KiB
C
/* follow.c
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*
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* $Id$
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*
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* Copyright 1998 Mike Hall <mlh@io.com>
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*
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* Wireshark - Network traffic analyzer
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* By Gerald Combs <gerald@wireshark.org>
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* Copyright 1998 Gerald Combs
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version 2
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* of the License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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*
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*/
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#ifdef HAVE_CONFIG_H
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# include "config.h"
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#endif
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#include <stdlib.h>
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#include <stdio.h>
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#include <string.h>
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#ifdef HAVE_UNISTD_H
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#include <unistd.h>
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#endif
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#include <glib.h>
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#include <epan/packet.h>
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#include <epan/ipproto.h>
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#include "follow.h"
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#define MAX_IPADDR_LEN 16
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typedef struct _tcp_frag {
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gulong seq;
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gulong len;
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gulong data_len;
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gchar *data;
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struct _tcp_frag *next;
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} tcp_frag;
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FILE* data_out_file = NULL;
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gboolean empty_tcp_stream;
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gboolean incomplete_tcp_stream;
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static guint8 ip_address[2][MAX_IPADDR_LEN];
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static guint port[2];
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static guint bytes_written[2];
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static gboolean is_ipv6 = FALSE;
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static int check_fragments( int, tcp_stream_chunk *, gulong );
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static void write_packet_data( int, tcp_stream_chunk *, const char * );
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void
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follow_stats(follow_stats_t* stats)
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{
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int i;
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for (i = 0; i < 2 ; i++) {
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memcpy(stats->ip_address[i], ip_address[i], MAX_IPADDR_LEN);
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stats->port[i] = port[i];
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stats->bytes_written[i] = bytes_written[i];
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stats->is_ipv6 = is_ipv6;
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}
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}
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/* this will build libpcap filter text that will only
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pass the packets related to the stream. There is a
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chance that two streams could intersect, but not a
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very good one */
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char*
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build_follow_filter( packet_info *pi ) {
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char* buf;
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int len;
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if( pi->net_src.type == AT_IPv4 && pi->net_dst.type == AT_IPv4
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&& pi->ipproto == IP_PROTO_TCP ) {
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/* TCP over IPv4 */
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buf = g_strdup_printf(
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"(ip.addr eq %s and ip.addr eq %s) and (tcp.port eq %d and tcp.port eq %d)",
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ip_to_str( pi->net_src.data),
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ip_to_str( pi->net_dst.data),
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pi->srcport, pi->destport );
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len = 4;
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is_ipv6 = FALSE;
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}
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else if( pi->net_src.type == AT_IPv4 && pi->net_dst.type == AT_IPv4
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&& pi->ipproto == IP_PROTO_UDP ) {
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/* UDP over IPv4 */
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buf = g_strdup_printf(
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"(ip.addr eq %s and ip.addr eq %s) and (udp.port eq %d and udp.port eq %d)",
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ip_to_str( pi->net_src.data),
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ip_to_str( pi->net_dst.data),
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pi->srcport, pi->destport );
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len = 4;
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is_ipv6 = FALSE;
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}
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else if( pi->net_src.type == AT_IPv6 && pi->net_dst.type == AT_IPv6
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&& pi->ipproto == IP_PROTO_TCP ) {
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/* TCP over IPv6 */
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buf = g_strdup_printf(
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"(ipv6.addr eq %s and ipv6.addr eq %s) and (tcp.port eq %d and tcp.port eq %d)",
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ip6_to_str((const struct e_in6_addr *)pi->net_src.data),
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ip6_to_str((const struct e_in6_addr *)pi->net_dst.data),
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pi->srcport, pi->destport );
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len = 16;
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is_ipv6 = TRUE;
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}
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else if( pi->net_src.type == AT_IPv6 && pi->net_dst.type == AT_IPv6
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&& pi->ipproto == IP_PROTO_UDP ) {
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/* UDP over IPv6 */
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buf = g_strdup_printf(
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"(ipv6.addr eq %s and ipv6.addr eq %s) and (udp.port eq %d and udp.port eq %d)",
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ip6_to_str((const struct e_in6_addr *)pi->net_src.data),
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ip6_to_str((const struct e_in6_addr *)pi->net_dst.data),
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pi->srcport, pi->destport );
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len = 16;
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is_ipv6 = TRUE;
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}
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else {
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return NULL;
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}
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memcpy(ip_address[0], pi->net_src.data, len);
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memcpy(ip_address[1], pi->net_dst.data, len);
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port[0] = pi->srcport;
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port[1] = pi->destport;
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return buf;
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}
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/* here we are going to try and reconstruct the data portion of a TCP
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session. We will try and handle duplicates, TCP fragments, and out
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of order packets in a smart way. */
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static tcp_frag *frags[2] = { 0, 0 };
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static gulong seq[2];
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static guint8 src_addr[2][MAX_IPADDR_LEN];
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static guint src_port[2] = { 0, 0 };
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void
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reassemble_tcp( gulong sequence, gulong acknowledgement, gulong length,
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const char* data, gulong data_length, int synflag,
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address *net_src, address *net_dst,
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guint srcport, guint dstport) {
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guint8 srcx[MAX_IPADDR_LEN], dstx[MAX_IPADDR_LEN];
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int src_index, j, first = 0, len;
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gulong newseq;
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tcp_frag *tmp_frag;
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tcp_stream_chunk sc;
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src_index = -1;
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/* First, check if this packet should be processed. */
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if ((net_src->type != AT_IPv4 && net_src->type != AT_IPv6) ||
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(net_dst->type != AT_IPv4 && net_dst->type != AT_IPv6))
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return;
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if (net_src->type == AT_IPv4)
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len = 4;
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else
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len = 16;
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/* Now check if the packet is for this connection. */
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memcpy(srcx, net_src->data, len);
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memcpy(dstx, net_dst->data, len);
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if (
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! (
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memcmp(srcx, ip_address[0], len) == 0 &&
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memcmp(dstx, ip_address[1], len) == 0 &&
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srcport == port[0] &&
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dstport == port[1]
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) &&
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! (
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memcmp(srcx, ip_address[1], len) == 0 &&
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memcmp(dstx, ip_address[0], len) == 0 &&
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srcport == port[1] &&
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dstport == port[0]
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)
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)
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return;
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/* Check to see if we have seen this source IP and port before.
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(Yes, we have to check both source IP and port; the connection
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might be between two different ports on the same machine.) */
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for( j=0; j<2; j++ ) {
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if (memcmp(src_addr[j], srcx, len) == 0 && src_port[j] == srcport ) {
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src_index = j;
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}
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}
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/* we didn't find it if src_index == -1 */
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if( src_index < 0 ) {
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/* assign it to a src_index and get going */
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for( j=0; j<2; j++ ) {
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if( src_port[j] == 0 ) {
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memcpy(src_addr[j], srcx, len);
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src_port[j] = srcport;
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src_index = j;
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first = 1;
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break;
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}
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}
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}
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if( src_index < 0 ) {
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fprintf( stderr, "ERROR in reassemble_tcp: Too many addresses!\n");
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return;
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}
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if( data_length < length ) {
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incomplete_tcp_stream = TRUE;
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}
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/* Before adding data for this flow to the data_out_file, check whether
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* this frame acks fragments that were already seen. This happens when
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* frames are not in the capture file, but were actually seen by the
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* receiving host (Fixes bug 592).
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*/
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if( frags[1-src_index] ) {
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memcpy(sc.src_addr, dstx, len);
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sc.src_port = dstport;
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sc.dlen = 0; /* Will be filled in in check_fragments */
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while ( check_fragments( 1-src_index, &sc, acknowledgement ) )
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;
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}
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/* Initialize our stream chunk. This data gets written to disk. */
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memcpy(sc.src_addr, srcx, len);
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sc.src_port = srcport;
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sc.dlen = data_length;
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/* now that we have filed away the srcs, lets get the sequence number stuff
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figured out */
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if( first ) {
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/* this is the first time we have seen this src's sequence number */
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seq[src_index] = sequence + length;
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if( synflag ) {
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seq[src_index]++;
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}
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/* write out the packet data */
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write_packet_data( src_index, &sc, data );
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return;
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}
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/* if we are here, we have already seen this src, let's
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try and figure out if this packet is in the right place */
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if( sequence < seq[src_index] ) {
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/* this sequence number seems dated, but
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check the end to make sure it has no more
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info than we have already seen */
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newseq = sequence + length;
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if( newseq > seq[src_index] ) {
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gulong new_len;
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/* this one has more than we have seen. let's get the
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payload that we have not seen. */
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new_len = seq[src_index] - sequence;
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if ( data_length <= new_len ) {
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data = NULL;
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data_length = 0;
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incomplete_tcp_stream = TRUE;
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} else {
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data += new_len;
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data_length -= new_len;
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}
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sc.dlen = data_length;
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sequence = seq[src_index];
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length = newseq - seq[src_index];
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/* this will now appear to be right on time :) */
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}
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}
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if ( sequence == seq[src_index] ) {
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/* right on time */
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seq[src_index] += length;
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if( synflag ) seq[src_index]++;
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if( data ) {
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write_packet_data( src_index, &sc, data );
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}
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/* done with the packet, see if it caused a fragment to fit */
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while( check_fragments( src_index, &sc, 0 ) )
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;
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}
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else {
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/* out of order packet */
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if(data_length > 0 && sequence > seq[src_index] ) {
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tmp_frag = (tcp_frag *)g_malloc( sizeof( tcp_frag ) );
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tmp_frag->data = (gchar *)g_malloc( data_length );
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tmp_frag->seq = sequence;
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tmp_frag->len = length;
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tmp_frag->data_len = data_length;
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memcpy( tmp_frag->data, data, data_length );
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if( frags[src_index] ) {
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tmp_frag->next = frags[src_index];
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} else {
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tmp_frag->next = NULL;
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}
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frags[src_index] = tmp_frag;
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}
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}
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} /* end reassemble_tcp */
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/* here we search through all the frag we have collected to see if
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one fits */
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static int
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check_fragments( int index, tcp_stream_chunk *sc, gulong acknowledged ) {
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tcp_frag *prev = NULL;
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tcp_frag *current;
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gulong lowest_seq;
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gchar *dummy_str;
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current = frags[index];
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if( current ) {
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lowest_seq = current->seq;
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while( current ) {
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if( (glong)(lowest_seq - current->seq) > 0 ) {
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lowest_seq = current->seq;
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}
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if( current->seq < seq[index] ) {
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gulong newseq;
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/* this sequence number seems dated, but
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check the end to make sure it has no more
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info than we have already seen */
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newseq = current->seq + current->len;
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if( newseq > seq[index] ) {
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gulong new_pos;
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/* this one has more than we have seen. let's get the
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payload that we have not seen. This happens when
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part of this frame has been retransmitted */
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new_pos = seq[index] - current->seq;
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if ( current->data_len > new_pos ) {
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sc->dlen = current->data_len - new_pos;
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write_packet_data( index, sc, current->data + new_pos );
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}
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seq[index] += (current->len - new_pos);
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if( prev ) {
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prev->next = current->next;
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} else {
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frags[index] = current->next;
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}
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g_free( current->data );
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g_free( current );
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return 1;
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}
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}
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if( current->seq == seq[index] ) {
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/* this fragment fits the stream */
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if( current->data ) {
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sc->dlen = current->data_len;
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write_packet_data( index, sc, current->data );
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}
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seq[index] += current->len;
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if( prev ) {
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prev->next = current->next;
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} else {
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frags[index] = current->next;
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}
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g_free( current->data );
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g_free( current );
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return 1;
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}
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prev = current;
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current = current->next;
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}
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if( (glong)(acknowledged - lowest_seq) > 0 ) {
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/* There are frames missing in the capture file that were seen
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* by the receiving host. Add dummy stream chunk with the data
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* "[xxx bytes missing in capture file]".
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*/
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dummy_str = g_strdup_printf("[%d bytes missing in capture file]",
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(int)(lowest_seq - seq[index]) );
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sc->dlen = strlen(dummy_str);
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write_packet_data( index, sc, dummy_str );
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g_free(dummy_str);
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seq[index] = lowest_seq;
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return 1;
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}
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}
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return 0;
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}
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/* this should always be called before we start to reassemble a stream */
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void
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reset_tcp_reassembly(void)
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{
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tcp_frag *current, *next;
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int i;
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empty_tcp_stream = TRUE;
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incomplete_tcp_stream = FALSE;
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for( i=0; i<2; i++ ) {
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seq[i] = 0;
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memset(src_addr[i], '\0', MAX_IPADDR_LEN);
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src_port[i] = 0;
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memset(ip_address[i], '\0', MAX_IPADDR_LEN);
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port[i] = 0;
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bytes_written[i] = 0;
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current = frags[i];
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while( current ) {
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next = current->next;
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g_free( current->data );
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g_free( current );
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current = next;
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}
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frags[i] = NULL;
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}
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}
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static void
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write_packet_data( int index, tcp_stream_chunk *sc, const char *data )
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{
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DISSECTOR_ASSERT(1 * sizeof(tcp_stream_chunk) == fwrite( sc, 1, sizeof(tcp_stream_chunk), data_out_file ));
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DISSECTOR_ASSERT(1 * sc->dlen == fwrite( data, 1, sc->dlen, data_out_file ));
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bytes_written[index] += sc->dlen;
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empty_tcp_stream = FALSE;
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}
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