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 #include <config.h>
  25
  26 #include "netdissect-stdinc.h"
  27
  28 #define ND_LONGJMP_FROM_TCHECK
  29 #include "netdissect.h"
  30 #include "extract.h"
  31
  32 #include "ip.h"
  33 #include "tcp.h"
  34 #include "slcompress.h"
  35
  36 /*
  37  * definitions of the pseudo- link-level header attached to slip
  38  * packets grabbed by the packet filter (bpf) traffic monitor.
  39  */
  40 #define SLIP_HDRLEN 16
  41
  42 #define SLX_DIR 0
  43 #define SLX_CHDR 1
  44
  45 #define SLIPDIR_IN 0
  46 #define SLIPDIR_OUT 1
  47
  48
  49 static u_int lastlen[2][256];
  50 static u_int lastconn = 255;
  51
  52 static void sliplink_print(netdissect_options *, const u_char *, const struct ip *, u_int);
  53 static void compressed_sl_print(netdissect_options *, const u_char *, const struct ip *, u_int, int);
  54
  55 void
  56 sl_if_print(netdissect_options *ndo,
  57             const struct pcap_pkthdr *h, const u_char *p)
  58 {
  59         u_int length = h->len;
  60         const struct ip *ip;
  61
  62         ndo->ndo_protocol = "slip";
  63         ND_TCHECK_LEN(p, SLIP_HDRLEN);
  64         ndo->ndo_ll_hdr_len += SLIP_HDRLEN;
  65
  66         length -= SLIP_HDRLEN;
  67
  68         ip = (const struct ip *)(p + SLIP_HDRLEN);
  69
  70         if (ndo->ndo_eflag)
  71                 sliplink_print(ndo, p, ip, length);
  72
  73         switch (IP_V(ip)) {
  74         case 4:
  75                 ip_print(ndo, (const u_char *)ip, length);
  76                 break;
  77         case 6:
  78                 ip6_print(ndo, (const u_char *)ip, length);
  79                 break;
  80         default:
  81                 ND_PRINT("ip v%u", IP_V(ip));
  82         }
  83 }
  84
  85 void
  86 sl_bsdos_if_print(netdissect_options *ndo,
  87                   const struct pcap_pkthdr *h, const u_char *p)
  88 {
  89         u_int length = h->len;
  90         const struct ip *ip;
  91
  92         ndo->ndo_protocol = "slip_bsdos";
  93         ND_TCHECK_LEN(p, SLIP_HDRLEN);
  94         ndo->ndo_ll_hdr_len += SLIP_HDRLEN;
  95
  96         length -= SLIP_HDRLEN;
  97
  98         ip = (const struct ip *)(p + SLIP_HDRLEN);
  99
 100 #ifdef notdef
 101         if (ndo->ndo_eflag)
 102                 sliplink_print(ndo, p, ip, length);
 103 #endif
 104
 105         ip_print(ndo, (const u_char *)ip, length);
 106 }
 107
 108 static void
 109 sliplink_print(netdissect_options *ndo,
 110                const u_char *p, const struct ip *ip,
 111                u_int length)
 112 {
 113         int dir;
 114         u_int hlen;
 115
 116         dir = GET_U_1(p + SLX_DIR);
 117         switch (dir) {
 118
 119         case SLIPDIR_IN:
 120                 ND_PRINT("I ");
 121                 break;
 122
 123         case SLIPDIR_OUT:
 124                 ND_PRINT("O ");
 125                 break;
 126
 127         default:
 128                 ND_PRINT("Invalid direction %d ", dir);
 129                 dir = -1;
 130                 break;
 131         }
 132         switch (GET_U_1(p + SLX_CHDR) & 0xf0) {
 133
 134         case TYPE_IP:
 135                 ND_PRINT("ip %u: ", length + SLIP_HDRLEN);
 136                 break;
 137
 138         case TYPE_UNCOMPRESSED_TCP:
 139                 /*
 140                  * The connection id is stored in the IP protocol field.
 141                  * Get it from the link layer since sl_uncompress_tcp()
 142                  * has restored the IP header copy to IPPROTO_TCP.
 143                  */
 144                 lastconn = GET_U_1(((const struct ip *)(p + SLX_CHDR))->ip_p);
 145                 ND_PRINT("utcp %u: ", lastconn);
 146                 if (dir == -1) {
 147                         /* Direction is bogus, don't use it */
 148                         return;
 149                 }
 150                 hlen = IP_HL(ip);
 151                 hlen += TH_OFF((const struct tcphdr *)&((const int *)ip)[hlen]);
 152                 lastlen[dir][lastconn] = length - (hlen << 2);
 153                 break;
 154
 155         default:
 156                 if (dir == -1) {
 157                         /* Direction is bogus, don't use it */
 158                         return;
 159                 }
 160                 if (GET_U_1(p + SLX_CHDR) & TYPE_COMPRESSED_TCP) {
 161                         compressed_sl_print(ndo, p + SLX_CHDR, ip, length, dir);
 162                         ND_PRINT(": ");
 163                 } else
 164                         ND_PRINT("slip-%u!: ", GET_U_1(p + SLX_CHDR));
 165         }
 166 }
 167
 168 static const u_char *
 169 print_sl_change(netdissect_options *ndo,
 170                 const char *str, const u_char *cp)
 171 {
 172         u_int i;
 173
 174         if ((i = GET_U_1(cp)) == 0) {
 175                 cp++;
 176                 i = GET_BE_U_2(cp);
 177                 cp += 2;
 178         }
 179         ND_PRINT(" %s%u", str, i);
 180         return (cp);
 181 }
 182
 183 static const u_char *
 184 print_sl_winchange(netdissect_options *ndo,
 185                    const u_char *cp)
 186 {
 187         int16_t i;
 188
 189         if ((i = GET_U_1(cp)) == 0) {
 190                 cp++;
 191                 i = GET_BE_S_2(cp);
 192                 cp += 2;
 193         }
 194         if (i >= 0)
 195                 ND_PRINT(" W+%d", i);
 196         else
 197                 ND_PRINT(" W%d", i);
 198         return (cp);
 199 }
 200
 201 static void
 202 compressed_sl_print(netdissect_options *ndo,
 203                     const u_char *chdr, const struct ip *ip,
 204                     u_int length, int dir)
 205 {
 206         const u_char *cp = chdr;
 207         u_int flags, hlen;
 208
 209         flags = GET_U_1(cp);
 210         cp++;
 211         if (flags & NEW_C) {
 212                 lastconn = GET_U_1(cp);
 213                 cp++;
 214                 ND_PRINT("ctcp %u", lastconn);
 215         } else
 216                 ND_PRINT("ctcp *");
 217
 218         /* skip tcp checksum */
 219         cp += 2;
 220
 221         switch (flags & SPECIALS_MASK) {
 222         case SPECIAL_I:
 223                 ND_PRINT(" *SA+%u", lastlen[dir][lastconn]);
 224                 break;
 225
 226         case SPECIAL_D:
 227                 ND_PRINT(" *S+%u", lastlen[dir][lastconn]);
 228                 break;
 229
 230         default:
 231                 if (flags & NEW_U)
 232                         cp = print_sl_change(ndo, "U=", cp);
 233                 if (flags & NEW_W)
 234                         cp = print_sl_winchange(ndo, cp);
 235                 if (flags & NEW_A)
 236                         cp = print_sl_change(ndo, "A+", cp);
 237                 if (flags & NEW_S)
 238                         cp = print_sl_change(ndo, "S+", cp);
 239                 break;
 240         }
 241         if (flags & NEW_I)
 242                 cp = print_sl_change(ndo, "I+", cp);
 243
 244         /*
 245          * 'hlen' is the length of the uncompressed TCP/IP header (in words).
 246          * 'cp - chdr' is the length of the compressed header.
 247          * 'length - hlen' is the amount of data in the packet.
 248          */
 249         hlen = IP_HL(ip);
 250         hlen += TH_OFF((const struct tcphdr *)&((const int32_t *)ip)[hlen]);
 251         lastlen[dir][lastconn] = length - (hlen << 2);
 252         ND_PRINT(" %u (%ld)", lastlen[dir][lastconn], (long)(cp - chdr));
 253 }