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