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831 lines
29 KiB
C
831 lines
29 KiB
C
/* $NetBSD: print-tcp.c,v 1.9 2007/07/26 18:15:12 plunky Exp $ */
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/*
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* Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
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* The Regents of the University of California. All rights reserved.
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*
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* Copyright (c) 1999-2004 The tcpdump.org project
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that: (1) source code distributions
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* retain the above copyright notice and this paragraph in its entirety, (2)
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* distributions including binary code include the above copyright notice and
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* this paragraph in its entirety in the documentation or other materials
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* provided with the distribution, and (3) all advertising materials mentioning
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* features or use of this software display the following acknowledgement:
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* ``This product includes software developed by the University of California,
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* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
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* the University nor the names of its contributors may be used to endorse
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* or promote products derived from this software without specific prior
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* written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*/
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#ifndef lint
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static const char rcsid[] _U_ =
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"@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.130.2.3 2007-12-22 03:08:45 guy Exp $ (LBL)";
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#else
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__RCSID("$NetBSD: print-tcp.c,v 1.8 2007/07/24 11:53:48 drochner Exp $");
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#endif
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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 <tcpdump-stdinc.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include "interface.h"
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#include "addrtoname.h"
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#include "extract.h"
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#include "tcp.h"
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#include "ip.h"
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#ifdef INET6
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#include "ip6.h"
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#endif
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#include "ipproto.h"
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#include "rpc_auth.h"
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#include "rpc_msg.h"
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#include "nameser.h"
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#ifdef HAVE_LIBCRYPTO
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#include <openssl/md5.h>
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#define SIGNATURE_VALID 0
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#define SIGNATURE_INVALID 1
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#define CANT_CHECK_SIGNATURE 2
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static int tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
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const u_char *data, int length, const u_char *rcvsig);
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#endif
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static void print_tcp_rst_data(register const u_char *sp, u_int length);
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#define MAX_RST_DATA_LEN 30
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struct tha {
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#ifndef INET6
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struct in_addr src;
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struct in_addr dst;
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#else
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struct in6_addr src;
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struct in6_addr dst;
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#endif /*INET6*/
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u_int port;
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};
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struct tcp_seq_hash {
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struct tcp_seq_hash *nxt;
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struct tha addr;
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tcp_seq seq;
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tcp_seq ack;
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};
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#define TSEQ_HASHSIZE 919
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/* These tcp optinos do not have the size octet */
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#define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)
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static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];
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struct tok tcp_flag_values[] = {
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{ TH_FIN, "F" },
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{ TH_SYN, "S" },
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{ TH_RST, "R" },
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{ TH_PUSH, "P" },
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{ TH_ACK, "." },
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{ TH_URG, "U" },
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{ TH_ECNECHO, "E" },
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{ TH_CWR, "W" },
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{ 0, NULL }
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};
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struct tok tcp_option_values[] = {
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{ TCPOPT_EOL, "eol" },
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{ TCPOPT_NOP, "nop" },
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{ TCPOPT_MAXSEG, "mss" },
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{ TCPOPT_WSCALE, "wscale" },
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{ TCPOPT_SACKOK, "sackOK" },
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{ TCPOPT_SACK, "sack" },
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{ TCPOPT_ECHO, "echo" },
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{ TCPOPT_ECHOREPLY, "echoreply" },
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{ TCPOPT_TIMESTAMP, "TS" },
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{ TCPOPT_CC, "cc" },
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{ TCPOPT_CCNEW, "ccnew" },
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{ TCPOPT_CCECHO, "" },
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{ TCPOPT_SIGNATURE, "md5" },
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{ TCPOPT_AUTH, "enhanced auth" },
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{ TCPOPT_UTO, "uto" },
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{ 0, NULL }
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};
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static int tcp_cksum(register const struct ip *ip,
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register const struct tcphdr *tp,
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register u_int len)
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{
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union phu {
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struct phdr {
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u_int32_t src;
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u_int32_t dst;
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u_char mbz;
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u_char proto;
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u_int16_t len;
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} ph;
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u_int16_t pa[6];
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} phu;
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const u_int16_t *sp;
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/* pseudo-header.. */
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phu.ph.len = htons((u_int16_t)len);
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phu.ph.mbz = 0;
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phu.ph.proto = IPPROTO_TCP;
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memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
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if (IP_HL(ip) == 5)
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memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
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else
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phu.ph.dst = ip_finddst(ip);
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sp = &phu.pa[0];
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return in_cksum((u_short *)tp, len,
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sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
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}
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#ifdef INET6
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static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
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u_int len)
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{
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size_t i;
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u_int32_t sum = 0;
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union {
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struct {
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struct in6_addr ph_src;
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struct in6_addr ph_dst;
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u_int32_t ph_len;
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u_int8_t ph_zero[3];
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u_int8_t ph_nxt;
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} ph;
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u_int16_t pa[20];
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} phu;
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/* pseudo-header */
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memset(&phu, 0, sizeof(phu));
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phu.ph.ph_src = ip6->ip6_src;
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phu.ph.ph_dst = ip6->ip6_dst;
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phu.ph.ph_len = htonl(len);
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phu.ph.ph_nxt = IPPROTO_TCP;
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for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
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sum += phu.pa[i];
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return in_cksum((u_short *)tp, len, sum);
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}
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#endif
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void
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tcp_print(register const u_char *bp, register u_int length,
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register const u_char *bp2, int fragmented)
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{
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register const struct tcphdr *tp;
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register const struct ip *ip;
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register u_char flags;
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register u_int hlen;
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register char ch;
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u_int16_t sport, dport, win, urp;
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u_int32_t seq, ack, thseq, thack;
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int threv;
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#ifdef INET6
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register const struct ip6_hdr *ip6;
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#endif
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tp = (struct tcphdr *)bp;
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ip = (struct ip *)bp2;
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#ifdef INET6
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if (IP_V(ip) == 6)
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ip6 = (struct ip6_hdr *)bp2;
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else
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ip6 = NULL;
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#endif /*INET6*/
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ch = '\0';
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if (!TTEST(tp->th_dport)) {
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(void)printf("%s > %s: [|tcp]",
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ipaddr_string(&ip->ip_src),
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ipaddr_string(&ip->ip_dst));
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return;
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}
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sport = EXTRACT_16BITS(&tp->th_sport);
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dport = EXTRACT_16BITS(&tp->th_dport);
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hlen = TH_OFF(tp) * 4;
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/*
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* If data present, header length valid, and NFS port used,
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* assume NFS.
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* Pass offset of data plus 4 bytes for RPC TCP msg length
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* to NFS print routines.
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*/
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if (!qflag && hlen >= sizeof(*tp) && hlen <= length &&
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(length - hlen) >= 4) {
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u_char *fraglenp;
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u_int32_t fraglen;
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register struct sunrpc_msg *rp;
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enum sunrpc_msg_type direction;
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fraglenp = (u_char *)tp + hlen;
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if (TTEST2(*fraglenp, 4)) {
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fraglen = EXTRACT_32BITS(fraglenp) & 0x7FFFFFFF;
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if (fraglen > (length - hlen) - 4)
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fraglen = (length - hlen) - 4;
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rp = (struct sunrpc_msg *)(fraglenp + 4);
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if (TTEST(rp->rm_direction)) {
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direction = (enum sunrpc_msg_type)EXTRACT_32BITS(&rp->rm_direction);
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if (dport == NFS_PORT &&
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direction == SUNRPC_CALL) {
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nfsreq_print((u_char *)rp, fraglen,
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(u_char *)ip);
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return;
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}
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if (sport == NFS_PORT &&
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direction == SUNRPC_REPLY) {
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nfsreply_print((u_char *)rp, fraglen,
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(u_char *)ip);
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return;
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}
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}
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}
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}
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#ifdef INET6
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if (ip6) {
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if (ip6->ip6_nxt == IPPROTO_TCP) {
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(void)printf("%s.%s > %s.%s: ",
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ip6addr_string(&ip6->ip6_src),
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tcpport_string(sport),
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ip6addr_string(&ip6->ip6_dst),
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tcpport_string(dport));
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} else {
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(void)printf("%s > %s: ",
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tcpport_string(sport), tcpport_string(dport));
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}
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} else
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#endif /*INET6*/
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{
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if (ip->ip_p == IPPROTO_TCP) {
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(void)printf("%s.%s > %s.%s: ",
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ipaddr_string(&ip->ip_src),
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tcpport_string(sport),
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ipaddr_string(&ip->ip_dst),
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tcpport_string(dport));
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} else {
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(void)printf("%s > %s: ",
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tcpport_string(sport), tcpport_string(dport));
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}
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}
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if (hlen < sizeof(*tp)) {
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(void)printf(" tcp %d [bad hdr length %u - too short, < %lu]",
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length - hlen, hlen, (unsigned long)sizeof(*tp));
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return;
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}
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TCHECK(*tp);
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seq = EXTRACT_32BITS(&tp->th_seq);
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ack = EXTRACT_32BITS(&tp->th_ack);
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win = EXTRACT_16BITS(&tp->th_win);
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urp = EXTRACT_16BITS(&tp->th_urp);
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if (qflag) {
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(void)printf("tcp %d", length - hlen);
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if (hlen > length) {
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(void)printf(" [bad hdr length %u - too long, > %u]",
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hlen, length);
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}
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return;
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}
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flags = tp->th_flags;
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printf("Flags [%s]", bittok2str_nosep(tcp_flag_values, "none", flags));
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if (!Sflag && (flags & TH_ACK)) {
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register struct tcp_seq_hash *th;
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const void *src, *dst;
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register int rev;
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struct tha tha;
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/*
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* Find (or record) the initial sequence numbers for
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* this conversation. (we pick an arbitrary
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* collating order so there's only one entry for
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* both directions).
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*/
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#ifdef INET6
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memset(&tha, 0, sizeof(tha));
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rev = 0;
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if (ip6) {
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src = &ip6->ip6_src;
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dst = &ip6->ip6_dst;
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if (sport > dport)
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rev = 1;
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else if (sport == dport) {
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if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
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rev = 1;
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}
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if (rev) {
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memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
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memcpy(&tha.dst, src, sizeof ip6->ip6_src);
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tha.port = dport << 16 | sport;
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} else {
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memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
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memcpy(&tha.src, src, sizeof ip6->ip6_src);
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tha.port = sport << 16 | dport;
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}
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} else {
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src = &ip->ip_src;
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dst = &ip->ip_dst;
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if (sport > dport)
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rev = 1;
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else if (sport == dport) {
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if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
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rev = 1;
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}
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if (rev) {
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memcpy(&tha.src, dst, sizeof ip->ip_dst);
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memcpy(&tha.dst, src, sizeof ip->ip_src);
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tha.port = dport << 16 | sport;
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} else {
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memcpy(&tha.dst, dst, sizeof ip->ip_dst);
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memcpy(&tha.src, src, sizeof ip->ip_src);
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tha.port = sport << 16 | dport;
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}
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}
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#else
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rev = 0;
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src = &ip->ip_src;
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dst = &ip->ip_dst;
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if (sport > dport)
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rev = 1;
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else if (sport == dport) {
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if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
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rev = 1;
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}
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if (rev) {
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memcpy(&tha.src, dst, sizeof ip->ip_dst);
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memcpy(&tha.dst, src, sizeof ip->ip_src);
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tha.port = dport << 16 | sport;
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} else {
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memcpy(&tha.dst, dst, sizeof ip->ip_dst);
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memcpy(&tha.src, src, sizeof ip->ip_src);
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tha.port = sport << 16 | dport;
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}
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#endif
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threv = rev;
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for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
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th->nxt; th = th->nxt)
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if (memcmp((char *)&tha, (char *)&th->addr,
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sizeof(th->addr)) == 0)
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break;
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if (!th->nxt || (flags & TH_SYN)) {
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/* didn't find it or new conversation */
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if (th->nxt == NULL) {
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th->nxt = (struct tcp_seq_hash *)
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calloc(1, sizeof(*th));
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if (th->nxt == NULL)
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error("tcp_print: calloc");
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}
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th->addr = tha;
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if (rev)
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th->ack = seq, th->seq = ack - 1;
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else
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th->seq = seq, th->ack = ack - 1;
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} else {
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if (rev)
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seq -= th->ack, ack -= th->seq;
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else
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seq -= th->seq, ack -= th->ack;
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}
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thseq = th->seq;
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thack = th->ack;
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} else {
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/*fool gcc*/
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thseq = thack = threv = 0;
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}
|
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if (hlen > length) {
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(void)printf(" [bad hdr length %u - too long, > %u]",
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hlen, length);
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return;
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}
|
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|
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if (IP_V(ip) == 4 && vflag && !Kflag && !fragmented) {
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u_int16_t sum, tcp_sum;
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if (TTEST2(tp->th_sport, length)) {
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sum = tcp_cksum(ip, tp, length);
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|
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(void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
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if (sum != 0) {
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tcp_sum = EXTRACT_16BITS(&tp->th_sum);
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(void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
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} else
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(void)printf(" (correct)");
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}
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}
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#ifdef INET6
|
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if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !Kflag && !fragmented) {
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u_int16_t sum,tcp_sum;
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if (TTEST2(tp->th_sport, length)) {
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sum = tcp6_cksum(ip6, tp, length);
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(void)printf(", cksum 0x%04x",EXTRACT_16BITS(&tp->th_sum));
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if (sum != 0) {
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tcp_sum = EXTRACT_16BITS(&tp->th_sum);
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(void)printf(" (incorrect -> 0x%04x)",in_cksum_shouldbe(tcp_sum, sum));
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} else
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(void)printf(" (correct)");
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|
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}
|
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}
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|
#endif
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|
|
length -= hlen;
|
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if (vflag > 1 || flags & (TH_SYN | TH_FIN | TH_RST)) {
|
|
(void)printf(", seq %u", seq);
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|
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if (length > 0) {
|
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(void)printf(":%u", seq + length);
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}
|
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}
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|
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if (flags & TH_ACK) {
|
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(void)printf(", ack %u", ack);
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}
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|
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(void)printf(", win %d", win);
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|
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if (flags & TH_URG)
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(void)printf(", urg %d", urp);
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/*
|
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* Handle any options.
|
|
*/
|
|
if (hlen > sizeof(*tp)) {
|
|
register const u_char *cp;
|
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register u_int i, opt, datalen;
|
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register u_int len;
|
|
|
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hlen -= sizeof(*tp);
|
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cp = (const u_char *)tp + sizeof(*tp);
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|
printf(", options [");
|
|
while (hlen > 0) {
|
|
if (ch != '\0')
|
|
putchar(ch);
|
|
TCHECK(*cp);
|
|
opt = *cp++;
|
|
if (ZEROLENOPT(opt))
|
|
len = 1;
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else {
|
|
TCHECK(*cp);
|
|
len = *cp++; /* total including type, len */
|
|
if (len < 2 || len > hlen)
|
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goto bad;
|
|
--hlen; /* account for length byte */
|
|
}
|
|
--hlen; /* account for type byte */
|
|
datalen = 0;
|
|
|
|
/* Bail if "l" bytes of data are not left or were not captured */
|
|
#define LENCHECK(l) { if ((l) > hlen) goto bad; TCHECK2(*cp, l); }
|
|
|
|
|
|
printf("%s", tok2str(tcp_option_values, "Unknown Option %u", opt));
|
|
|
|
switch (opt) {
|
|
|
|
case TCPOPT_MAXSEG:
|
|
datalen = 2;
|
|
LENCHECK(datalen);
|
|
(void)printf(" %u", EXTRACT_16BITS(cp));
|
|
break;
|
|
|
|
case TCPOPT_WSCALE:
|
|
datalen = 1;
|
|
LENCHECK(datalen);
|
|
(void)printf(" %u", *cp);
|
|
break;
|
|
|
|
case TCPOPT_SACK:
|
|
datalen = len - 2;
|
|
if (datalen % 8 != 0) {
|
|
(void)printf("malformed sack");
|
|
} else {
|
|
u_int32_t s, e;
|
|
|
|
(void)printf(" %d ", datalen / 8);
|
|
for (i = 0; i < datalen; i += 8) {
|
|
LENCHECK(i + 4);
|
|
s = EXTRACT_32BITS(cp + i);
|
|
LENCHECK(i + 8);
|
|
e = EXTRACT_32BITS(cp + i + 4);
|
|
if (threv) {
|
|
s -= thseq;
|
|
e -= thseq;
|
|
} else {
|
|
s -= thack;
|
|
e -= thack;
|
|
}
|
|
(void)printf("{%u:%u}", s, e);
|
|
}
|
|
}
|
|
break;
|
|
|
|
case TCPOPT_CC:
|
|
case TCPOPT_CCNEW:
|
|
case TCPOPT_CCECHO:
|
|
case TCPOPT_ECHO:
|
|
case TCPOPT_ECHOREPLY:
|
|
|
|
/*
|
|
* those options share their semantics.
|
|
* fall through
|
|
*/
|
|
datalen = 4;
|
|
LENCHECK(datalen);
|
|
(void)printf(" %u", EXTRACT_32BITS(cp));
|
|
break;
|
|
|
|
case TCPOPT_TIMESTAMP:
|
|
datalen = 8;
|
|
LENCHECK(datalen);
|
|
(void)printf(" val %u ecr %u",
|
|
EXTRACT_32BITS(cp),
|
|
EXTRACT_32BITS(cp + 4));
|
|
break;
|
|
|
|
case TCPOPT_SIGNATURE:
|
|
datalen = TCP_SIGLEN;
|
|
LENCHECK(datalen);
|
|
#ifdef HAVE_LIBCRYPTO
|
|
switch (tcp_verify_signature(ip, tp,
|
|
bp + TH_OFF(tp) * 4, length, cp)) {
|
|
|
|
case SIGNATURE_VALID:
|
|
(void)printf("valid");
|
|
break;
|
|
|
|
case SIGNATURE_INVALID:
|
|
(void)printf("invalid");
|
|
break;
|
|
|
|
case CANT_CHECK_SIGNATURE:
|
|
(void)printf("can't check - ");
|
|
for (i = 0; i < TCP_SIGLEN; ++i)
|
|
(void)printf("%02x", cp[i]);
|
|
break;
|
|
}
|
|
#else
|
|
for (i = 0; i < TCP_SIGLEN; ++i)
|
|
(void)printf("%02x", cp[i]);
|
|
#endif
|
|
break;
|
|
|
|
case TCPOPT_AUTH:
|
|
(void)printf("keyid %d", *cp++);
|
|
datalen = len - 3;
|
|
for (i = 0; i < datalen; ++i) {
|
|
LENCHECK(i);
|
|
(void)printf("%02x", cp[i]);
|
|
}
|
|
break;
|
|
|
|
|
|
case TCPOPT_EOL:
|
|
case TCPOPT_NOP:
|
|
case TCPOPT_SACKOK:
|
|
/*
|
|
* Nothing interesting.
|
|
* fall through
|
|
*/
|
|
break;
|
|
|
|
case TCPOPT_UTO:
|
|
datalen = 2;
|
|
LENCHECK(datalen);
|
|
uint utoval = EXTRACT_16BITS(cp);
|
|
if (utoval & 0x0001)
|
|
utoval = (utoval >> 1) * 60;
|
|
else
|
|
utoval >>= 1;
|
|
(void)printf(" %u", utoval);
|
|
break;
|
|
|
|
default:
|
|
datalen = len - 2;
|
|
for (i = 0; i < datalen; ++i) {
|
|
LENCHECK(i);
|
|
(void)printf("%02x", cp[i]);
|
|
}
|
|
break;
|
|
}
|
|
|
|
/* Account for data printed */
|
|
cp += datalen;
|
|
hlen -= datalen;
|
|
|
|
/* Check specification against observed length */
|
|
++datalen; /* option octet */
|
|
if (!ZEROLENOPT(opt))
|
|
++datalen; /* size octet */
|
|
if (datalen != len)
|
|
(void)printf("[len %d]", len);
|
|
ch = ',';
|
|
if (opt == TCPOPT_EOL)
|
|
break;
|
|
}
|
|
putchar(']');
|
|
}
|
|
|
|
/*
|
|
* Print length field before crawling down the stack.
|
|
*/
|
|
printf(", length %u", length);
|
|
|
|
if (length <= 0)
|
|
return;
|
|
|
|
/*
|
|
* Decode payload if necessary.
|
|
*/
|
|
bp += TH_OFF(tp) * 4;
|
|
if ((flags & TH_RST) && vflag) {
|
|
print_tcp_rst_data(bp, length);
|
|
return;
|
|
}
|
|
|
|
if (sport == TELNET_PORT || dport == TELNET_PORT) {
|
|
if (!qflag && vflag)
|
|
telnet_print(bp, length);
|
|
} else if (sport == BGP_PORT || dport == BGP_PORT)
|
|
bgp_print(bp, length);
|
|
else if (sport == PPTP_PORT || dport == PPTP_PORT)
|
|
pptp_print(bp);
|
|
#ifdef TCPDUMP_DO_SMB
|
|
else if (sport == NETBIOS_SSN_PORT || dport == NETBIOS_SSN_PORT)
|
|
nbt_tcp_print(bp, length);
|
|
else if (sport == SMB_PORT || dport == SMB_PORT)
|
|
smb_tcp_print(bp, length);
|
|
#endif
|
|
else if (sport == BEEP_PORT || dport == BEEP_PORT)
|
|
beep_print(bp, length);
|
|
else if (length > 2 &&
|
|
(sport == NAMESERVER_PORT || dport == NAMESERVER_PORT ||
|
|
sport == MULTICASTDNS_PORT || dport == MULTICASTDNS_PORT)) {
|
|
/*
|
|
* TCP DNS query has 2byte length at the head.
|
|
* XXX packet could be unaligned, it can go strange
|
|
*/
|
|
ns_print(bp + 2, length - 2, 0);
|
|
} else if (sport == MSDP_PORT || dport == MSDP_PORT) {
|
|
msdp_print(bp, length);
|
|
}
|
|
else if (length > 0 && (sport == LDP_PORT || dport == LDP_PORT)) {
|
|
ldp_print(bp, length);
|
|
}
|
|
|
|
return;
|
|
bad:
|
|
fputs("[bad opt]", stdout);
|
|
if (ch != '\0')
|
|
putchar('>');
|
|
return;
|
|
trunc:
|
|
fputs("[|tcp]", stdout);
|
|
if (ch != '\0')
|
|
putchar('>');
|
|
}
|
|
|
|
/*
|
|
* RFC1122 says the following on data in RST segments:
|
|
*
|
|
* 4.2.2.12 RST Segment: RFC-793 Section 3.4
|
|
*
|
|
* A TCP SHOULD allow a received RST segment to include data.
|
|
*
|
|
* DISCUSSION
|
|
* It has been suggested that a RST segment could contain
|
|
* ASCII text that encoded and explained the cause of the
|
|
* RST. No standard has yet been established for such
|
|
* data.
|
|
*
|
|
*/
|
|
|
|
static void
|
|
print_tcp_rst_data(register const u_char *sp, u_int length)
|
|
{
|
|
int c;
|
|
|
|
if (TTEST2(*sp, length))
|
|
printf(" [RST");
|
|
else
|
|
printf(" [!RST");
|
|
if (length > MAX_RST_DATA_LEN) {
|
|
length = MAX_RST_DATA_LEN; /* can use -X for longer */
|
|
putchar('+'); /* indicate we truncate */
|
|
}
|
|
putchar(' ');
|
|
while (length-- && sp <= snapend) {
|
|
c = *sp++;
|
|
safeputchar(c);
|
|
}
|
|
putchar(']');
|
|
}
|
|
|
|
#ifdef HAVE_LIBCRYPTO
|
|
static int
|
|
tcp_verify_signature(const struct ip *ip, const struct tcphdr *tp,
|
|
const u_char *data, int length, const u_char *rcvsig)
|
|
{
|
|
struct tcphdr tp1;
|
|
u_char sig[TCP_SIGLEN];
|
|
char zero_proto = 0;
|
|
MD5_CTX ctx;
|
|
u_int16_t savecsum, tlen;
|
|
#ifdef INET6
|
|
struct ip6_hdr *ip6;
|
|
u_int32_t len32;
|
|
u_int8_t nxt;
|
|
#endif
|
|
|
|
tp1 = *tp;
|
|
|
|
if (tcpmd5secret == NULL)
|
|
return (CANT_CHECK_SIGNATURE);
|
|
|
|
MD5_Init(&ctx);
|
|
/*
|
|
* Step 1: Update MD5 hash with IP pseudo-header.
|
|
*/
|
|
if (IP_V(ip) == 4) {
|
|
MD5_Update(&ctx, (char *)&ip->ip_src, sizeof(ip->ip_src));
|
|
MD5_Update(&ctx, (char *)&ip->ip_dst, sizeof(ip->ip_dst));
|
|
MD5_Update(&ctx, (char *)&zero_proto, sizeof(zero_proto));
|
|
MD5_Update(&ctx, (char *)&ip->ip_p, sizeof(ip->ip_p));
|
|
tlen = EXTRACT_16BITS(&ip->ip_len) - IP_HL(ip) * 4;
|
|
tlen = htons(tlen);
|
|
MD5_Update(&ctx, (char *)&tlen, sizeof(tlen));
|
|
#ifdef INET6
|
|
} else if (IP_V(ip) == 6) {
|
|
ip6 = (struct ip6_hdr *)ip;
|
|
MD5_Update(&ctx, (char *)&ip6->ip6_src, sizeof(ip6->ip6_src));
|
|
MD5_Update(&ctx, (char *)&ip6->ip6_dst, sizeof(ip6->ip6_dst));
|
|
len32 = htonl(ntohs(ip6->ip6_plen));
|
|
MD5_Update(&ctx, (char *)&len32, sizeof(len32));
|
|
nxt = 0;
|
|
MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
|
|
MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
|
|
MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
|
|
nxt = IPPROTO_TCP;
|
|
MD5_Update(&ctx, (char *)&nxt, sizeof(nxt));
|
|
#endif
|
|
} else
|
|
return (CANT_CHECK_SIGNATURE);
|
|
|
|
/*
|
|
* Step 2: Update MD5 hash with TCP header, excluding options.
|
|
* The TCP checksum must be set to zero.
|
|
*/
|
|
savecsum = tp1.th_sum;
|
|
tp1.th_sum = 0;
|
|
MD5_Update(&ctx, (char *)&tp1, sizeof(struct tcphdr));
|
|
tp1.th_sum = savecsum;
|
|
/*
|
|
* Step 3: Update MD5 hash with TCP segment data, if present.
|
|
*/
|
|
if (length > 0)
|
|
MD5_Update(&ctx, data, length);
|
|
/*
|
|
* Step 4: Update MD5 hash with shared secret.
|
|
*/
|
|
MD5_Update(&ctx, tcpmd5secret, strlen(tcpmd5secret));
|
|
MD5_Final(sig, &ctx);
|
|
|
|
if (memcmp(rcvsig, sig, TCP_SIGLEN) == 0)
|
|
return (SIGNATURE_VALID);
|
|
else
|
|
return (SIGNATURE_INVALID);
|
|
}
|
|
#endif /* HAVE_LIBCRYPTO */
|
|
|
|
/*
|
|
* Local Variables:
|
|
* c-style: whitesmith
|
|
* c-basic-offset: 8
|
|
* End:
|
|
*/
|