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print-tcp.c

/*
 * Copyright (c) 1988, 1989, 1990, 1991, 1992, 1993, 1994, 1995, 1996, 1997
 *    The Regents of the University of California.  All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that: (1) source code distributions
 * retain the above copyright notice and this paragraph in its entirety, (2)
 * distributions including binary code include the above copyright notice and
 * this paragraph in its entirety in the documentation or other materials
 * provided with the distribution, and (3) all advertising materials mentioning
 * features or use of this software display the following acknowledgement:
 * ``This product includes software developed by the University of California,
 * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
 * the University nor the names of its contributors may be used to endorse
 * or promote products derived from this software without specific prior
 * written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

#ifndef lint
static const char rcsid[] _U_ =
    "@(#) $Header: /tcpdump/master/tcpdump/print-tcp.c,v 1.107.2.3 2003/11/19 00:17:02 guy Exp $ (LBL)";
#endif

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include <tcpdump-stdinc.h>

#include <rpc/rpc.h>

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "interface.h"
#include "addrtoname.h"
#include "extract.h"

#include "tcp.h"

#include "ip.h"
#ifdef INET6
#include "ip6.h"
#endif
#include "ipproto.h"

#include "nameser.h"

static void print_tcp_rst_data(register const u_char *sp, u_int length);

#define MAX_RST_DATA_LEN      30


struct tha {
#ifndef INET6
      struct in_addr src;
      struct in_addr dst;
#else
      struct in6_addr src;
      struct in6_addr dst;
#endif /*INET6*/
      u_int port;
};

struct tcp_seq_hash {
      struct tcp_seq_hash *nxt;
      struct tha addr;
      tcp_seq seq;
      tcp_seq ack;
};

#define TSEQ_HASHSIZE 919

/* These tcp optinos do not have the size octet */
#define ZEROLENOPT(o) ((o) == TCPOPT_EOL || (o) == TCPOPT_NOP)

static struct tcp_seq_hash tcp_seq_hash[TSEQ_HASHSIZE];


#ifndef TELNET_PORT
#define TELNET_PORT     23
#endif
#ifndef BGP_PORT
#define BGP_PORT  179
#endif
#define NETBIOS_SSN_PORT 139
#ifndef PPTP_PORT
#define PPTP_PORT 1723
#endif
#define BEEP_PORT        10288
#ifndef NFS_PORT
#define NFS_PORT  2049
#endif
#define MSDP_PORT 639
#define LDP_PORT        646

static int tcp_cksum(register const struct ip *ip,
                 register const struct tcphdr *tp,
                 register u_int len)
{
      union phu {
            struct phdr {
                  u_int32_t src;
                  u_int32_t dst;
                  u_char mbz;
                  u_char proto;
                  u_int16_t len;
            } ph;
            u_int16_t pa[6];
      } phu;
      const u_int16_t *sp;

      /* pseudo-header.. */
      phu.ph.len = htons((u_int16_t)len);
      phu.ph.mbz = 0;
      phu.ph.proto = IPPROTO_TCP;
      memcpy(&phu.ph.src, &ip->ip_src.s_addr, sizeof(u_int32_t));
      if (IP_HL(ip) == 5)
            memcpy(&phu.ph.dst, &ip->ip_dst.s_addr, sizeof(u_int32_t));
      else
            phu.ph.dst = ip_finddst(ip);

      sp = &phu.pa[0];
      return in_cksum((u_short *)tp, len,
                  sp[0]+sp[1]+sp[2]+sp[3]+sp[4]+sp[5]);
}

#ifdef INET6
static int tcp6_cksum(const struct ip6_hdr *ip6, const struct tcphdr *tp,
      u_int len)
{
      size_t i;
      register const u_int16_t *sp;
      u_int32_t sum;
      union {
            struct {
                  struct in6_addr ph_src;
                  struct in6_addr ph_dst;
                  u_int32_t   ph_len;
                  u_int8_t    ph_zero[3];
                  u_int8_t    ph_nxt;
            } ph;
            u_int16_t pa[20];
      } phu;

      /* pseudo-header */
      memset(&phu, 0, sizeof(phu));
      phu.ph.ph_src = ip6->ip6_src;
      phu.ph.ph_dst = ip6->ip6_dst;
      phu.ph.ph_len = htonl(len);
      phu.ph.ph_nxt = IPPROTO_TCP;

      sum = 0;
      for (i = 0; i < sizeof(phu.pa) / sizeof(phu.pa[0]); i++)
            sum += phu.pa[i];

      sp = (const u_int16_t *)tp;

      for (i = 0; i < (len & ~1); i += 2)
            sum += *sp++;

      if (len & 1)
            sum += htons((*(const u_int8_t *)sp) << 8);

      while (sum > 0xffff)
            sum = (sum & 0xffff) + (sum >> 16);
      sum = ~sum & 0xffff;

      return (sum);
}
#endif

void
tcp_print(register const u_char *bp, register u_int length,
        register const u_char *bp2, int fragmented)
{
      register const struct tcphdr *tp;
      register const struct ip *ip;
      register u_char flags;
      register u_int hlen;
      register char ch;
      u_int16_t sport, dport, win, urp;
      u_int32_t seq, ack, thseq, thack;
      int threv;
#ifdef INET6
      register const struct ip6_hdr *ip6;
#endif

      tp = (struct tcphdr *)bp;
      ip = (struct ip *)bp2;
#ifdef INET6
      if (IP_V(ip) == 6)
            ip6 = (struct ip6_hdr *)bp2;
      else
            ip6 = NULL;
#endif /*INET6*/
      ch = '\0';
      if (!TTEST(tp->th_dport)) {
            (void)printf("%s > %s: [|tcp]",
                  ipaddr_string(&ip->ip_src),
                  ipaddr_string(&ip->ip_dst));
            return;
      }

      sport = EXTRACT_16BITS(&tp->th_sport);
      dport = EXTRACT_16BITS(&tp->th_dport);

      hlen = TH_OFF(tp) * 4;

      /*
       * If data present and NFS port used, assume NFS.
       * Pass offset of data plus 4 bytes for RPC TCP msg length
       * to NFS print routines.
       */
      if (!qflag) {
            if ((u_char *)tp + 4 + sizeof(struct rpc_msg) <= snapend &&
                dport == NFS_PORT) {
                  nfsreq_print((u_char *)tp + hlen + 4, length - hlen,
                             (u_char *)ip);
                  return;
            } else if ((u_char *)tp + 4 + sizeof(struct rpc_msg)
                     <= snapend &&
                     sport == NFS_PORT) {
                  nfsreply_print((u_char *)tp + hlen + 4, length - hlen,
                               (u_char *)ip);
                  return;
            }
      }
#ifdef INET6
      if (ip6) {
            if (ip6->ip6_nxt == IPPROTO_TCP) {
                  (void)printf("%s.%s > %s.%s: ",
                        ip6addr_string(&ip6->ip6_src),
                        tcpport_string(sport),
                        ip6addr_string(&ip6->ip6_dst),
                        tcpport_string(dport));
            } else {
                  (void)printf("%s > %s: ",
                        tcpport_string(sport), tcpport_string(dport));
            }
      } else
#endif /*INET6*/
      {
            if (ip->ip_p == IPPROTO_TCP) {
                  (void)printf("%s.%s > %s.%s: ",
                        ipaddr_string(&ip->ip_src),
                        tcpport_string(sport),
                        ipaddr_string(&ip->ip_dst),
                        tcpport_string(dport));
            } else {
                  (void)printf("%s > %s: ",
                        tcpport_string(sport), tcpport_string(dport));
            }
      }

      TCHECK(*tp);

      seq = EXTRACT_32BITS(&tp->th_seq);
      ack = EXTRACT_32BITS(&tp->th_ack);
      win = EXTRACT_16BITS(&tp->th_win);
      urp = EXTRACT_16BITS(&tp->th_urp);

      if (qflag) {
            (void)printf("tcp %d", length - TH_OFF(tp) * 4);
            return;
      }
      if ((flags = tp->th_flags) & (TH_SYN|TH_FIN|TH_RST|TH_PUSH|
                              TH_ECNECHO|TH_CWR)) {
            if (flags & TH_SYN)
                  putchar('S');
            if (flags & TH_FIN)
                  putchar('F');
            if (flags & TH_RST)
                  putchar('R');
            if (flags & TH_PUSH)
                  putchar('P');
            if (flags & TH_CWR)
                  putchar('W');     /* congestion _W_indow reduced (ECN) */
            if (flags & TH_ECNECHO)
                  putchar('E');     /* ecn _E_cho sent (ECN) */
      } else
            putchar('.');

      if (!Sflag && (flags & TH_ACK)) {
            register struct tcp_seq_hash *th;
            const void *src, *dst;
            register int rev;
            struct tha tha;
            /*
             * Find (or record) the initial sequence numbers for
             * this conversation.  (we pick an arbitrary
             * collating order so there's only one entry for
             * both directions).
             */
#ifdef INET6
            memset(&tha, 0, sizeof(tha));
            rev = 0;
            if (ip6) {
                  src = &ip6->ip6_src;
                  dst = &ip6->ip6_dst;
                  if (sport > dport)
                        rev = 1;
                  else if (sport == dport) {
                        if (memcmp(src, dst, sizeof ip6->ip6_dst) > 0)
                              rev = 1;
                  }
                  if (rev) {
                        memcpy(&tha.src, dst, sizeof ip6->ip6_dst);
                        memcpy(&tha.dst, src, sizeof ip6->ip6_src);
                        tha.port = dport << 16 | sport;
                  } else {
                        memcpy(&tha.dst, dst, sizeof ip6->ip6_dst);
                        memcpy(&tha.src, src, sizeof ip6->ip6_src);
                        tha.port = sport << 16 | dport;
                  }
            } else {
                  src = &ip->ip_src;
                  dst = &ip->ip_dst;
                  if (sport > dport)
                        rev = 1;
                  else if (sport == dport) {
                        if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
                              rev = 1;
                  }
                  if (rev) {
                        memcpy(&tha.src, dst, sizeof ip->ip_dst);
                        memcpy(&tha.dst, src, sizeof ip->ip_src);
                        tha.port = dport << 16 | sport;
                  } else {
                        memcpy(&tha.dst, dst, sizeof ip->ip_dst);
                        memcpy(&tha.src, src, sizeof ip->ip_src);
                        tha.port = sport << 16 | dport;
                  }
            }
#else
            rev = 0;
            src = &ip->ip_src;
            dst = &ip->ip_dst;
            if (sport > dport)
                  rev = 1;
            else if (sport == dport) {
                  if (memcmp(src, dst, sizeof ip->ip_dst) > 0)
                        rev = 1;
            }
            if (rev) {
                  memcpy(&tha.src, dst, sizeof ip->ip_dst);
                  memcpy(&tha.dst, src, sizeof ip->ip_src);
                  tha.port = dport << 16 | sport;
            } else {
                  memcpy(&tha.dst, dst, sizeof ip->ip_dst);
                  memcpy(&tha.src, src, sizeof ip->ip_src);
                  tha.port = sport << 16 | dport;
            }
#endif

            threv = rev;
            for (th = &tcp_seq_hash[tha.port % TSEQ_HASHSIZE];
                 th->nxt; th = th->nxt)
                  if (memcmp((char *)&tha, (char *)&th->addr,
                          sizeof(th->addr)) == 0)
                        break;

            if (!th->nxt || (flags & TH_SYN)) {
                  /* didn't find it or new conversation */
                  if (th->nxt == NULL) {
                        th->nxt = (struct tcp_seq_hash *)
                              calloc(1, sizeof(*th));
                        if (th->nxt == NULL)
                              error("tcp_print: calloc");
                  }
                  th->addr = tha;
                  if (rev)
                        th->ack = seq, th->seq = ack - 1;
                  else
                        th->seq = seq, th->ack = ack - 1;
            } else {
                  if (rev)
                        seq -= th->ack, ack -= th->seq;
                  else
                        seq -= th->seq, ack -= th->ack;
            }

            thseq = th->seq;
            thack = th->ack;
      } else {
            /*fool gcc*/
            thseq = thack = threv = 0;
      }
      if (hlen > length) {
            (void)printf(" [bad hdr length]");
            return;
      }

      if (IP_V(ip) == 4 && vflag && !fragmented) {
            u_int16_t sum, tcp_sum;
            if (TTEST2(tp->th_sport, length)) {
                  sum = tcp_cksum(ip, tp, length);
                  if (sum != 0) {
                        tcp_sum = EXTRACT_16BITS(&tp->th_sum);
                        (void)printf(" [bad tcp cksum %x (->%x)!]",
                            tcp_sum, in_cksum_shouldbe(tcp_sum, sum));
                  } else
                        (void)printf(" [tcp sum ok]");
            }
      }
#ifdef INET6
      if (IP_V(ip) == 6 && ip6->ip6_plen && vflag && !fragmented) {
            int sum;
            if (TTEST2(tp->th_sport, length)) {
                  sum = tcp6_cksum(ip6, tp, length);
                  if (sum != 0)
                        (void)printf(" [bad tcp cksum %x!]", sum);
                  else
                        (void)printf(" [tcp sum ok]");
            }
      }
#endif

      length -= hlen;
      if (vflag > 1 || length > 0 || flags & (TH_SYN | TH_FIN | TH_RST))
            (void)printf(" %u:%u(%u)", seq, seq + length, length);
      if (flags & TH_ACK)
            (void)printf(" ack %u", ack);

      (void)printf(" win %d", win);

      if (flags & TH_URG)
            (void)printf(" urg %d", urp);
      /*
       * Handle any options.
       */
      if (hlen > sizeof(*tp)) {
            register const u_char *cp;
            register u_int i, opt, datalen;
            register u_int len;

            hlen -= sizeof(*tp);
            cp = (const u_char *)tp + sizeof(*tp);
            putchar(' ');
            ch = '<';
            while (hlen > 0) {
                  putchar(ch);
                  TCHECK(*cp);
                  opt = *cp++;
                  if (ZEROLENOPT(opt))
                        len = 1;
                  else {
                        TCHECK(*cp);
                        len = *cp++;      /* total including type, len */
                        if (len < 2 || len > hlen)
                              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); }

                  switch (opt) {

                  case TCPOPT_MAXSEG:
                        (void)printf("mss");
                        datalen = 2;
                        LENCHECK(datalen);
                        (void)printf(" %u", EXTRACT_16BITS(cp));

                        break;

                  case TCPOPT_EOL:
                        (void)printf("eol");
                        break;

                  case TCPOPT_NOP:
                        (void)printf("nop");
                        break;

                  case TCPOPT_WSCALE:
                        (void)printf("wscale");
                        datalen = 1;
                        LENCHECK(datalen);
                        (void)printf(" %u", *cp);
                        break;

                  case TCPOPT_SACKOK:
                        (void)printf("sackOK");
                        break;

                  case TCPOPT_SACK:
                        (void)printf("sack");
                        datalen = len - 2;
                        if (datalen % 8 != 0) {
                              (void)printf(" malformed sack ");
                        } else {
                              u_int32_t s, e;

                              (void)printf(" sack %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);
                              }
                              (void)printf(" ");
                        }
                        break;

                  case TCPOPT_ECHO:
                        (void)printf("echo");
                        datalen = 4;
                        LENCHECK(datalen);
                        (void)printf(" %u", EXTRACT_32BITS(cp));
                        break;

                  case TCPOPT_ECHOREPLY:
                        (void)printf("echoreply");
                        datalen = 4;
                        LENCHECK(datalen);
                        (void)printf(" %u", EXTRACT_32BITS(cp));
                        break;

                  case TCPOPT_TIMESTAMP:
                        (void)printf("timestamp");
                        datalen = 8;
                        LENCHECK(4);
                        (void)printf(" %u", EXTRACT_32BITS(cp));
                        LENCHECK(datalen);
                        (void)printf(" %u", EXTRACT_32BITS(cp + 4));
                        break;

                  case TCPOPT_CC:
                        (void)printf("cc");
                        datalen = 4;
                        LENCHECK(datalen);
                        (void)printf(" %u", EXTRACT_32BITS(cp));
                        break;

                  case TCPOPT_CCNEW:
                        (void)printf("ccnew");
                        datalen = 4;
                        LENCHECK(datalen);
                        (void)printf(" %u", EXTRACT_32BITS(cp));
                        break;

                  case TCPOPT_CCECHO:
                        (void)printf("ccecho");
                        datalen = 4;
                        LENCHECK(datalen);
                        (void)printf(" %u", EXTRACT_32BITS(cp));
                        break;

                  default:
                        (void)printf("opt-%u:", opt);
                        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('>');
      }

      if (length <= 0)
            return;

      /*
       * Decode payload if necessary.
       */
      bp += TH_OFF(tp) * 4;
      if (flags & TH_RST) {
            if (vflag)
                  print_tcp_rst_data(bp, length);
      } else {
            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);
#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 (sport == LDP_PORT || dport == LDP_PORT)
                        printf(": LDP, length: %u", 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(']');
}

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