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wireshark/packet-tcp.c

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/* packet-tcp.c
* Routines for TCP packet disassembly
*
* $Id: packet-tcp.c,v 1.5 1998/10/13 05:40:04 guy Exp $
*
* Ethereal - Network traffic analyzer
* By Gerald Combs <gerald@zing.org>
* Copyright 1998 Gerald Combs
*
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif
#include <gtk/gtk.h>
#include <stdio.h>
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#include "ethereal.h"
#include "packet.h"
#include "follow.h"
extern FILE* data_out_file;
extern packet_info pi;
static void
dissect_tcpopt_maxseg(GtkWidget *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
add_item_to_tree(opt_tree, offset, optlen,
"%s: %u bytes", name, pntohs(opd));
}
static void
dissect_tcpopt_wscale(GtkWidget *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
add_item_to_tree(opt_tree, offset, optlen,
"%s: %u bytes", name, *opd);
}
static void
dissect_tcpopt_sack(GtkWidget *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
GtkWidget *field_tree = NULL, *tf;
guint leftedge, rightedge;
tf = add_item_to_tree(opt_tree, offset, optlen, "%s:", name);
offset += 2; /* skip past type and length */
optlen -= 2; /* subtract size of type and length */
while (optlen > 0) {
if (field_tree == NULL) {
/* Haven't yet made a subtree out of this option. Do so. */
field_tree = gtk_tree_new();
add_subtree(tf, field_tree, ETT_TCP_OPTION_SACK);
}
if (optlen < 4) {
add_item_to_tree(field_tree, offset, optlen,
"(suboption would go past end of option)");
break;
}
/* XXX - check whether it goes past end of packet */
leftedge = pntohl(opd);
opd += 4;
optlen -= 4;
if (optlen < 4) {
add_item_to_tree(field_tree, offset, optlen,
"(suboption would go past end of option)");
break;
}
/* XXX - check whether it goes past end of packet */
rightedge = pntohl(opd);
opd += 4;
optlen -= 4;
add_item_to_tree(field_tree, offset, 8,
"left edge = %u, right edge = %u", leftedge, rightedge);
offset += 8;
}
}
static void
dissect_tcpopt_echo(GtkWidget *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
add_item_to_tree(opt_tree, offset, optlen,
"%s: %u", name, pntohl(opd));
}
static void
dissect_tcpopt_timestamp(GtkWidget *opt_tree, const char *name,
const u_char *opd, int offset, guint optlen)
{
add_item_to_tree(opt_tree, offset, optlen,
"%s: tsval %u, tsecr %u", name, pntohl(opd), pntohl(opd + 4));
}
static void
dissect_tcpopt_cc(GtkWidget *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
add_item_to_tree(opt_tree, offset, optlen,
"%s: %u", name, pntohl(opd));
}
static ip_tcp_opt tcpopts[] = {
{
TCPOPT_EOL,
"EOL",
NO_LENGTH,
0,
NULL,
},
{
TCPOPT_NOP,
"NOP",
NO_LENGTH,
0,
NULL,
},
{
TCPOPT_MSS,
"Maximum segment size",
FIXED_LENGTH,
TCPOLEN_MSS,
dissect_tcpopt_maxseg
},
{
TCPOPT_WINDOW,
"Window scale",
FIXED_LENGTH,
TCPOLEN_WINDOW,
dissect_tcpopt_wscale
},
{
TCPOPT_SACK_PERM,
"SACK permitted",
FIXED_LENGTH,
TCPOLEN_SACK_PERM,
NULL,
},
{
TCPOPT_SACK,
"SACK",
VARIABLE_LENGTH,
TCPOLEN_SACK_MIN,
dissect_tcpopt_sack
},
{
TCPOPT_ECHO,
"Echo",
FIXED_LENGTH,
TCPOLEN_ECHO,
dissect_tcpopt_echo
},
{
TCPOPT_ECHOREPLY,
"Echo reply",
FIXED_LENGTH,
TCPOLEN_ECHOREPLY,
dissect_tcpopt_echo
},
{
TCPOPT_TIMESTAMP,
"Time stamp",
FIXED_LENGTH,
TCPOLEN_TIMESTAMP,
dissect_tcpopt_timestamp
},
{
TCPOPT_CC,
"CC",
FIXED_LENGTH,
TCPOLEN_CC,
dissect_tcpopt_cc
},
{
TCPOPT_CCNEW,
"CC.NEW",
FIXED_LENGTH,
TCPOPT_CCNEW,
dissect_tcpopt_cc
},
{
TCPOPT_CCECHO,
"CC.ECHO",
FIXED_LENGTH,
TCPOLEN_CCECHO,
dissect_tcpopt_cc
}
};
#define N_TCP_OPTS (sizeof tcpopts / sizeof tcpopts[0])
void
dissect_tcp(const u_char *pd, int offset, frame_data *fd, GtkTree *tree) {
e_tcphdr th;
GtkWidget *tcp_tree, *ti, *field_tree, *tf;
gchar flags[64] = "<None>";
gchar *fstr[] = {"FIN", "SYN", "RST", "PSH", "ACK", "URG"};
gint fpos = 0, i;
guint bpos;
guint hlen;
guint optlen;
/* To do: Check for {cap len,pkt len} < struct len */
/* Avoids alignment problems on many architectures. */
memcpy(&th, &pd[offset], sizeof(e_tcphdr));
th.th_sport = ntohs(th.th_sport);
th.th_dport = ntohs(th.th_dport);
th.th_win = ntohs(th.th_win);
th.th_sum = ntohs(th.th_sum);
th.th_urp = ntohs(th.th_urp);
th.th_seq = ntohl(th.th_seq);
th.th_ack = ntohl(th.th_ack);
for (i = 0; i < 6; i++) {
bpos = 1 << i;
if (th.th_flags & bpos) {
if (fpos) {
strcpy(&flags[fpos], ", ");
fpos += 2;
}
strcpy(&flags[fpos], fstr[i]);
fpos += 3;
}
}
flags[fpos] = '\0';
if (fd->win_info[COL_NUM]) {
strcpy(fd->win_info[COL_PROTOCOL], "TCP");
sprintf(fd->win_info[COL_INFO], "Source port: %d Destination port: %d",
th.th_sport, th.th_dport);
}
hlen = th.th_off * 4; /* TCP header length, in bytes */
if (tree) {
ti = add_item_to_tree(GTK_WIDGET(tree), offset, hlen,
"Transmission Control Protocol");
tcp_tree = gtk_tree_new();
add_subtree(ti, tcp_tree, ETT_TCP);
add_item_to_tree(tcp_tree, offset, 2, "Source port: %d", th.th_sport);
add_item_to_tree(tcp_tree, offset + 2, 2, "Destination port: %d", th.th_dport);
add_item_to_tree(tcp_tree, offset + 4, 4, "Sequence number: %u",
th.th_seq);
if (th.th_flags & TH_ACK)
add_item_to_tree(tcp_tree, offset + 8, 4, "Acknowledgement number: %u",
th.th_ack);
add_item_to_tree(tcp_tree, offset + 12, 1, "Header length: %d bytes", hlen);
add_item_to_tree(tcp_tree, offset + 13, 1, "Flags: %s", flags);
add_item_to_tree(tcp_tree, offset + 14, 2, "Window size: %d", th.th_win);
add_item_to_tree(tcp_tree, offset + 16, 2, "Checksum: 0x%04x", th.th_sum);
if (th.th_flags & TH_URG)
add_item_to_tree(tcp_tree, offset + 18, 2, "Urgent pointer: 0x%04x",
th.th_urp);
/* Decode TCP options, if any. */
if (hlen > sizeof (e_tcphdr)) {
/* There's more than just the fixed-length header. Decode the
options. */
optlen = hlen - sizeof (e_tcphdr); /* length of options, in bytes */
tf = add_item_to_tree(tcp_tree, offset + 20, optlen,
"Options: (%d bytes)", optlen);
field_tree = gtk_tree_new();
add_subtree(tf, field_tree, ETT_TCP_OPTIONS);
dissect_ip_tcp_options(field_tree, &pd[offset + 20], offset + 20, optlen,
tcpopts, N_TCP_OPTS, TCPOPT_EOL);
}
}
/* Skip over header + options */
offset += hlen;
/* until we decode those options, I'll check the packet length
to see if there's more data. -- gilbert */
if (fd->cap_len > offset) {
switch(MIN(th.th_sport, th.th_dport)) {
case TCP_PORT_PRINTER:
dissect_lpd(pd, offset, fd, tree);
break;
default:
dissect_data(pd, offset, fd, tree);
}
}
pi.srcport = th.th_sport;
pi.destport = th.th_dport;
if( data_out_file ) {
reassemble_tcp( th.th_seq, /* sequence number */
( pi.iplen -( pi.iphdrlen * 4 )-( th.th_off * 4 ) ), /* length */
( pd+offset ), /* data */
( th.th_flags & 0x02 ), /* is syn set? */
pi.ip_src ); /* src ip */
}
}
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