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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 1.20 1999/04/06 02:02:11 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
#ifdef HAVE_SYS_TYPES_H
# include <sys/types.h>
#endif
#ifdef HAVE_NETINET_IN_H
# include <netinet/in.h>
#endif
#include <stdio.h>
#include <glib.h>
#include "packet.h"
#include "resolv.h"
#include "follow.h"
#include "util.h"
#ifdef NEED_SNPRINTF_H
# ifdef HAVE_STDARG_H
# include <stdarg.h>
# else
# include <varargs.h>
# endif
# include "snprintf.h"
#endif
#ifndef __PACKET_IP_H__
#include "packet-ip.h"
#endif
extern FILE* data_out_file;
extern packet_info pi;
static gchar info_str[COL_MAX_LEN];
static int info_len;
/* TCP Ports */
#define TCP_PORT_FTPDATA 20
#define TCP_PORT_FTP 21
#define TCP_PORT_TELNET 23
#define TCP_PORT_SMTP 25
#define TCP_PORT_HTTP 80
#define TCP_PORT_POP 110
#define TCP_PORT_NNTP 119
#define TCP_PORT_PRINTER 515
#define TCP_ALT_PORT_HTTP 8080
/* TCP structs and definitions */
typedef struct _e_tcphdr {
guint16 th_sport;
guint16 th_dport;
guint32 th_seq;
guint32 th_ack;
guint8 th_off_x2; /* combines th_off and th_x2 */
guint8 th_flags;
#define TH_FIN 0x01
#define TH_SYN 0x02
#define TH_RST 0x04
#define TH_PUSH 0x08
#define TH_ACK 0x10
#define TH_URG 0x20
guint16 th_win;
guint16 th_sum;
guint16 th_urp;
} e_tcphdr;
/*
* TCP option
*/
#define TCPOPT_NOP 1 /* Padding */
#define TCPOPT_EOL 0 /* End of options */
#define TCPOPT_MSS 2 /* Segment size negotiating */
#define TCPOPT_WINDOW 3 /* Window scaling */
#define TCPOPT_SACK_PERM 4 /* SACK Permitted */
#define TCPOPT_SACK 5 /* SACK Block */
#define TCPOPT_ECHO 6
#define TCPOPT_ECHOREPLY 7
#define TCPOPT_TIMESTAMP 8 /* Better RTT estimations/PAWS */
#define TCPOPT_CC 11
#define TCPOPT_CCNEW 12
#define TCPOPT_CCECHO 13
/*
* TCP option lengths
*/
#define TCPOLEN_MSS 4
#define TCPOLEN_WINDOW 3
#define TCPOLEN_SACK_PERM 2
#define TCPOLEN_SACK_MIN 2
#define TCPOLEN_ECHO 6
#define TCPOLEN_ECHOREPLY 6
#define TCPOLEN_TIMESTAMP 10
#define TCPOLEN_CC 6
#define TCPOLEN_CCNEW 6
#define TCPOLEN_CCECHO 6
static void
tcp_info_append_uint(const char *abbrev, guint32 val) {
int add_len = 0;
if (info_len > 0)
if(info_len > 0)
add_len = snprintf(&info_str[info_len], COL_MAX_LEN - info_len, " %s=%u",
abbrev, val);
if (add_len > 0)
info_len += add_len;
}
static void
dissect_tcpopt_maxseg(proto_tree *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
proto_tree_add_item(opt_tree, offset, optlen,
"%s: %u bytes", name, pntohs(opd));
tcp_info_append_uint("MSS", pntohs(opd));
}
static void
dissect_tcpopt_wscale(proto_tree *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
proto_tree_add_item(opt_tree, offset, optlen,
"%s: %u bytes", name, *opd);
tcp_info_append_uint("WS", *opd);
}
static void
dissect_tcpopt_sack(proto_tree *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
proto_tree *field_tree = NULL;
proto_item *tf;
guint leftedge, rightedge;
tf = proto_tree_add_item(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 = proto_tree_new();
proto_item_add_subtree(tf, field_tree, ETT_TCP_OPTION_SACK);
}
if (optlen < 4) {
proto_tree_add_item(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) {
proto_tree_add_item(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;
proto_tree_add_item(field_tree, offset, 8,
"left edge = %u, right edge = %u", leftedge, rightedge);
tcp_info_append_uint("SLE", leftedge);
tcp_info_append_uint("SRE", rightedge);
offset += 8;
}
}
static void
dissect_tcpopt_echo(proto_tree *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
proto_tree_add_item(opt_tree, offset, optlen,
"%s: %u", name, pntohl(opd));
tcp_info_append_uint("ECHO", pntohl(opd));
}
static void
dissect_tcpopt_timestamp(proto_tree *opt_tree, const char *name,
const u_char *opd, int offset, guint optlen)
{
proto_tree_add_item(opt_tree, offset, optlen,
"%s: tsval %u, tsecr %u", name, pntohl(opd), pntohl(opd + 4));
tcp_info_append_uint("TSV", pntohl(opd));
tcp_info_append_uint("TSER", pntohl(opd + 4));
}
static void
dissect_tcpopt_cc(proto_tree *opt_tree, const char *name, const u_char *opd,
int offset, guint optlen)
{
proto_tree_add_item(opt_tree, offset, optlen,
"%s: %u", name, pntohl(opd));
tcp_info_append_uint("CC", 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, proto_tree *tree) {
e_tcphdr th;
proto_tree *tcp_tree = NULL, *field_tree = NULL;
proto_item *ti, *tf;
gchar flags[64] = "<None>";
gchar *fstr[] = {"FIN", "SYN", "RST", "PSH", "ACK", "URG"};
gint fpos = 0, i;
guint bpos;
guint hlen;
guint optlen;
guint packet_max = pi.payload + offset;
guint payload;
/* 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);
info_len = 0;
if (check_col(fd, COL_PROTOCOL) || tree) {
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';
}
hlen = hi_nibble(th.th_off_x2) * 4; /* TCP header length, in bytes */
payload = pi.payload - hlen;
if (check_col(fd, COL_RES_SRC_PORT))
col_add_str(fd, COL_RES_SRC_PORT, get_tcp_port(th.th_sport));
if (check_col(fd, COL_UNRES_SRC_PORT))
col_add_fstr(fd, COL_UNRES_SRC_PORT, "%u", th.th_sport);
if (check_col(fd, COL_RES_DST_PORT))
col_add_str(fd, COL_RES_DST_PORT, get_tcp_port(th.th_dport));
if (check_col(fd, COL_UNRES_DST_PORT))
col_add_fstr(fd, COL_UNRES_DST_PORT, "%u", th.th_dport);
if (check_col(fd, COL_PROTOCOL))
col_add_str(fd, COL_PROTOCOL, "TCP");
if (check_col(fd, COL_INFO)) {
/* Copy the data into info_str in case one of the option handling
routines needs to append to it. */
if (th.th_flags & TH_URG)
info_len = snprintf(info_str, COL_MAX_LEN, "%s > %s [%s] Seq=%u Ack=%u Win=%u Urg=%u",
get_tcp_port(th.th_sport), get_tcp_port(th.th_dport), flags,
th.th_seq, th.th_ack, th.th_win, th.th_urp);
else
info_len = snprintf(info_str, COL_MAX_LEN, "%s > %s [%s] Seq=%u Ack=%u Win=%u",
get_tcp_port(th.th_sport), get_tcp_port(th.th_dport), flags,
th.th_seq, th.th_ack, th.th_win);
/* The info column is actually written after the options are decoded */
}
if (tree) {
ti = proto_tree_add_item(tree, offset, hlen,
"Transmission Control Protocol");
tcp_tree = proto_tree_new();
proto_item_add_subtree(ti, tcp_tree, ETT_TCP);
proto_tree_add_item(tcp_tree, offset, 2, "Source port: %s (%u)",
get_tcp_port(th.th_sport), th.th_sport);
proto_tree_add_item(tcp_tree, offset + 2, 2, "Destination port: %s (%u)",
get_tcp_port(th.th_dport), th.th_dport);
proto_tree_add_item(tcp_tree, offset + 4, 4, "Sequence number: %u",
th.th_seq);
if (th.th_flags & TH_ACK)
proto_tree_add_item(tcp_tree, offset + 8, 4, "Acknowledgement number: %u",
th.th_ack);
proto_tree_add_item(tcp_tree, offset + 12, 1, "Header length: %u bytes", hlen);
tf = proto_tree_add_item(tcp_tree, offset + 13, 1, "Flags: 0x%x", th.th_flags);
field_tree = proto_tree_new();
proto_item_add_subtree(tf, field_tree, ETT_TCP_FLAGS);
proto_tree_add_item(field_tree, offset + 13, 1, "%s",
decode_boolean_bitfield(th.th_flags, TH_URG, sizeof (th.th_flags)*8,
"Urgent pointer", "No urgent pointer"));
proto_tree_add_item(field_tree, offset + 13, 1, "%s",
decode_boolean_bitfield(th.th_flags, TH_ACK, sizeof (th.th_flags)*8,
"Acknowledgment", "No acknowledgment"));
proto_tree_add_item(field_tree, offset + 13, 1, "%s",
decode_boolean_bitfield(th.th_flags, TH_PUSH, sizeof (th.th_flags)*8,
"Push", "No push"));
proto_tree_add_item(field_tree, offset + 13, 1, "%s",
decode_boolean_bitfield(th.th_flags, TH_RST, sizeof (th.th_flags)*8,
"Reset", "No reset"));
proto_tree_add_item(field_tree, offset + 13, 1, "%s",
decode_boolean_bitfield(th.th_flags, TH_SYN, sizeof (th.th_flags)*8,
"Syn", "No Syn"));
proto_tree_add_item(field_tree, offset + 13, 1, "%s",
decode_boolean_bitfield(th.th_flags, TH_FIN, sizeof (th.th_flags)*8,
"Fin", "No Fin"));
proto_tree_add_item(tcp_tree, offset + 14, 2, "Window size: %u", th.th_win);
proto_tree_add_item(tcp_tree, offset + 16, 2, "Checksum: 0x%04x", th.th_sum);
if (th.th_flags & TH_URG)
proto_tree_add_item(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 */
if (tree) {
tf = proto_tree_add_item(tcp_tree, offset + 20, optlen,
"Options: (%d bytes)", optlen);
field_tree = proto_tree_new();
proto_item_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);
}
if (check_col(fd, COL_INFO))
col_add_str(fd, COL_INFO, info_str);
/* Skip over header + options */
offset += hlen;
pi.srcport = th.th_sport;
pi.destport = th.th_dport;
/* Check the packet length to see if there's more data
(it could be an ACK-only packet) */
if (packet_max > offset) {
switch(MIN(th.th_sport, th.th_dport)) {
case TCP_PORT_PRINTER:
dissect_lpd(pd, offset, fd, tree);
break;
case TCP_PORT_TELNET:
pi.match_port = TCP_PORT_TELNET;
dissect_telnet(pd, offset, fd, tree, payload);
break;
case TCP_PORT_FTPDATA:
pi.match_port = TCP_PORT_FTPDATA;
dissect_ftpdata(pd, offset, fd, tree, payload);
break;
case TCP_PORT_FTP:
pi.match_port = TCP_PORT_FTP;
dissect_ftp(pd, offset, fd, tree, payload);
break;
case TCP_PORT_POP:
pi.match_port = TCP_PORT_POP;
dissect_pop(pd, offset, fd, tree, payload);
break;
case TCP_PORT_NNTP:
pi.match_port = TCP_PORT_NNTP;
dissect_nntp(pd, offset, fd, tree, payload);
break;
case TCP_PORT_HTTP:
case TCP_ALT_PORT_HTTP:
dissect_http(pd, offset, fd, tree);
break;
default:
/* check existence of high level protocols */
if (memcmp(&pd[offset], "GIOP", 4) == 0) {
dissect_giop(pd, offset, fd, tree);
}
else {
dissect_data(pd, offset, fd, tree);
}
}
}
if( data_out_file ) {
reassemble_tcp( th.th_seq, /* sequence number */
( pi.iplen -( pi.iphdrlen * 4 )-( hi_nibble(th.th_off_x2) * 4 ) ), /* length */
( pd+offset ), /* data */
( fd->cap_len - offset ), /* captured data length */
( th.th_flags & 0x02 ), /* is syn set? */
pi.ip_src ); /* src ip */
}
}
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