The Tcpdump Group git mirrors - tcpdump/blob - print-sl.c

   1 /*
   2  * Copyright (c) 1989, 1990, 1991, 1993, 1994, 1995, 1996, 1997
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that: (1) source code distributions
   7  * retain the above copyright notice and this paragraph in its entirety, (2)
   8  * distributions including binary code include the above copyright notice and
   9  * this paragraph in its entirety in the documentation or other materials
  10  * provided with the distribution, and (3) all advertising materials mentioning
  11  * features or use of this software display the following acknowledgement:
  12  * ``This product includes software developed by the University of California,
  13  * Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
  14  * the University nor the names of its contributors may be used to endorse
  15  * or promote products derived from this software without specific prior
  16  * written permission.
  17  * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
  18  * WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
  19  * MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
  20  */
  21
  22 /* \summary: Compressed Serial Line Internet Protocol printer */
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include <config.h>
  26 #endif
  27
  28 #include "netdissect-stdinc.h"
  29
  30 #include "netdissect.h"
  31 #include "extract.h"
  32
  33 #include "ip.h"
  34 #include "tcp.h"
  35 #include "slcompress.h"
  36
  37 /*
  38  * definitions of the pseudo- link-level header attached to slip
  39  * packets grabbed by the packet filter (bpf) traffic monitor.
  40  */
  41 #define SLIP_HDRLEN 16
  42
  43 #define SLX_DIR 0
  44 #define SLX_CHDR 1
  45 #define CHDR_LEN 15
  46
  47 #define SLIPDIR_IN 0
  48 #define SLIPDIR_OUT 1
  49
  50
  51 static u_int lastlen[2][256];
  52 static u_int lastconn = 255;
  53
  54 static int sliplink_print(netdissect_options *, const u_char *, const struct ip *, u_int);
  55 static int compressed_sl_print(netdissect_options *, const u_char *, const struct ip *, u_int, int);
  56
  57 void
  58 sl_if_print(netdissect_options *ndo,
  59             const struct pcap_pkthdr *h, const u_char *p)
  60 {
  61         u_int caplen = h->caplen;
  62         u_int length = h->len;
  63         const struct ip *ip;
  64
  65         ndo->ndo_protocol = "slip";
  66         if (caplen < SLIP_HDRLEN) {
  67                 nd_print_trunc(ndo);
  68                 ndo->ndo_ll_hdr_len += caplen;
  69                 return;
  70         }
  71         ndo->ndo_ll_hdr_len += SLIP_HDRLEN;
  72
  73         caplen -= SLIP_HDRLEN;
  74         length -= SLIP_HDRLEN;
  75
  76         ip = (const struct ip *)(p + SLIP_HDRLEN);
  77
  78         if (ndo->ndo_eflag)
  79                 if (sliplink_print(ndo, p, ip, length) == -1) {
  80                         nd_print_trunc(ndo);
  81                         return;
  82                 }
  83
  84         switch (IP_V(ip)) {
  85         case 4:
  86                 ip_print(ndo, (const u_char *)ip, length);
  87                 break;
  88         case 6:
  89                 ip6_print(ndo, (const u_char *)ip, length);
  90                 break;
  91         default:
  92                 ND_PRINT("ip v%u", IP_V(ip));
  93         }
  94 }
  95
  96 void
  97 sl_bsdos_if_print(netdissect_options *ndo,
  98                   const struct pcap_pkthdr *h, const u_char *p)
  99 {
 100         u_int caplen = h->caplen;
 101         u_int length = h->len;
 102         const struct ip *ip;
 103
 104         ndo->ndo_protocol = "slip_bsdos";
 105         if (caplen < SLIP_HDRLEN) {
 106                 nd_print_trunc(ndo);
 107                 ndo->ndo_ll_hdr_len += caplen;
 108                 return;
 109         }
 110         ndo->ndo_ll_hdr_len += SLIP_HDRLEN;
 111
 112         length -= SLIP_HDRLEN;
 113
 114         ip = (const struct ip *)(p + SLIP_HDRLEN);
 115
 116 #ifdef notdef
 117         if (ndo->ndo_eflag)
 118                 sliplink_print(ndo, p, ip, length);
 119 #endif
 120
 121         ip_print(ndo, (const u_char *)ip, length);
 122 }
 123
 124 static int
 125 sliplink_print(netdissect_options *ndo,
 126                const u_char *p, const struct ip *ip,
 127                u_int length)
 128 {
 129         int dir;
 130         u_int hlen;
 131
 132         dir = GET_U_1(p + SLX_DIR);
 133         switch (dir) {
 134
 135         case SLIPDIR_IN:
 136                 ND_PRINT("I ");
 137                 break;
 138
 139         case SLIPDIR_OUT:
 140                 ND_PRINT("O ");
 141                 break;
 142
 143         default:
 144                 ND_PRINT("Invalid direction %d ", dir);
 145                 dir = -1;
 146                 break;
 147         }
 148         switch (GET_U_1(p + SLX_CHDR) & 0xf0) {
 149
 150         case TYPE_IP:
 151                 ND_PRINT("ip %u: ", length + SLIP_HDRLEN);
 152                 break;
 153
 154         case TYPE_UNCOMPRESSED_TCP:
 155                 /*
 156                  * The connection id is stored in the IP protocol field.
 157                  * Get it from the link layer since sl_uncompress_tcp()
 158                  * has restored the IP header copy to IPPROTO_TCP.
 159                  */
 160                 lastconn = GET_U_1(((const struct ip *)(p + SLX_CHDR))->ip_p);
 161                 ND_PRINT("utcp %u: ", lastconn);
 162                 if (dir == -1) {
 163                         /* Direction is bogus, don't use it */
 164                         return 0;
 165                 }
 166                 ND_TCHECK_SIZE(ip);
 167                 hlen = IP_HL(ip);
 168                 ND_TCHECK_SIZE((const struct tcphdr *)&((const int *)ip)[hlen]);
 169                 hlen += TH_OFF((const struct tcphdr *)&((const int *)ip)[hlen]);
 170                 lastlen[dir][lastconn] = length - (hlen << 2);
 171                 break;
 172
 173         default:
 174                 if (dir == -1) {
 175                         /* Direction is bogus, don't use it */
 176                         return 0;
 177                 }
 178                 if (GET_U_1(p + SLX_CHDR) & TYPE_COMPRESSED_TCP) {
 179                         if (compressed_sl_print(ndo, p + SLX_CHDR, ip,
 180                                                 length, dir) == -1)
 181                                 goto trunc;
 182                         ND_PRINT(": ");
 183                 } else
 184                         ND_PRINT("slip-%u!: ", GET_U_1(p + SLX_CHDR));
 185         }
 186         return 0;
 187 trunc:
 188         return -1;
 189 }
 190
 191 static const u_char *
 192 print_sl_change(netdissect_options *ndo,
 193                 const char *str, const u_char *cp)
 194 {
 195         u_int i;
 196
 197         if ((i = GET_U_1(cp)) == 0) {
 198                 cp++;
 199                 i = GET_BE_U_2(cp);
 200                 cp += 2;
 201         }
 202         ND_PRINT(" %s%u", str, i);
 203         return (cp);
 204 }
 205
 206 static const u_char *
 207 print_sl_winchange(netdissect_options *ndo,
 208                    const u_char *cp)
 209 {
 210         int16_t i;
 211
 212         if ((i = GET_U_1(cp)) == 0) {
 213                 cp++;
 214                 i = GET_BE_S_2(cp);
 215                 cp += 2;
 216         }
 217         if (i >= 0)
 218                 ND_PRINT(" W+%d", i);
 219         else
 220                 ND_PRINT(" W%d", i);
 221         return (cp);
 222 }
 223
 224 static int
 225 compressed_sl_print(netdissect_options *ndo,
 226                     const u_char *chdr, const struct ip *ip,
 227                     u_int length, int dir)
 228 {
 229         const u_char *cp = chdr;
 230         u_int flags, hlen;
 231
 232         flags = GET_U_1(cp);
 233         cp++;
 234         if (flags & NEW_C) {
 235                 lastconn = GET_U_1(cp);
 236                 cp++;
 237                 ND_PRINT("ctcp %u", lastconn);
 238         } else
 239                 ND_PRINT("ctcp *");
 240
 241         /* skip tcp checksum */
 242         cp += 2;
 243
 244         switch (flags & SPECIALS_MASK) {
 245         case SPECIAL_I:
 246                 ND_PRINT(" *SA+%u", lastlen[dir][lastconn]);
 247                 break;
 248
 249         case SPECIAL_D:
 250                 ND_PRINT(" *S+%u", lastlen[dir][lastconn]);
 251                 break;
 252
 253         default:
 254                 if (flags & NEW_U)
 255                         cp = print_sl_change(ndo, "U=", cp);
 256                 if (flags & NEW_W)
 257                         cp = print_sl_winchange(ndo, cp);
 258                 if (flags & NEW_A)
 259                         cp = print_sl_change(ndo, "A+", cp);
 260                 if (flags & NEW_S)
 261                         cp = print_sl_change(ndo, "S+", cp);
 262                 break;
 263         }
 264         if (flags & NEW_I)
 265                 cp = print_sl_change(ndo, "I+", cp);
 266
 267         /*
 268          * 'hlen' is the length of the uncompressed TCP/IP header (in words).
 269          * 'cp - chdr' is the length of the compressed header.
 270          * 'length - hlen' is the amount of data in the packet.
 271          */
 272         ND_TCHECK_SIZE(ip);
 273         hlen = IP_HL(ip);
 274         ND_TCHECK_SIZE((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
 275         hlen += TH_OFF((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
 276         lastlen[dir][lastconn] = length - (hlen << 2);
 277         ND_PRINT(" %u (%ld)", lastlen[dir][lastconn], (long)(cp - chdr));
 278         return 0;
 279 trunc:
 280         return -1;
 281 }