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

   1 /*
   2  * Copyright (c) 1988, 1989, 1990, 1991, 1992, 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 #ifndef lint
  22 static const char rcsid[] _U_ =
  23     "@(#) $Header: /tcpdump/master/tcpdump/print-sll.c,v 1.19 2005-11-13 12:12:43 guy Exp $ (LBL)";
  24 #endif
  25
  26 #ifdef HAVE_CONFIG_H
  27 #include "config.h"
  28 #endif
  29
  30 #include <tcpdump-stdinc.h>
  31
  32 #include <stdio.h>
  33 #include <string.h>
  34 #include <pcap.h>
  35
  36 #include "interface.h"
  37 #include "addrtoname.h"
  38 #include "ethertype.h"
  39 #include "extract.h"
  40
  41 #include "ether.h"
  42
  43 /*
  44  * For captures on Linux cooked sockets, we construct a fake header
  45  * that includes:
  46  *
  47  *      a 2-byte "packet type" which is one of:
  48  *
  49  *              LINUX_SLL_HOST          packet was sent to us
  50  *              LINUX_SLL_BROADCAST     packet was broadcast
  51  *              LINUX_SLL_MULTICAST     packet was multicast
  52  *              LINUX_SLL_OTHERHOST     packet was sent to somebody else
  53  *              LINUX_SLL_OUTGOING      packet was sent *by* us;
  54  *
  55  *      a 2-byte Ethernet protocol field;
  56  *
  57  *      a 2-byte link-layer type;
  58  *
  59  *      a 2-byte link-layer address length;
  60  *
  61  *      an 8-byte source link-layer address, whose actual length is
  62  *      specified by the previous value.
  63  *
  64  * All fields except for the link-layer address are in network byte order.
  65  *
  66  * DO NOT change the layout of this structure, or change any of the
  67  * LINUX_SLL_ values below.  If you must change the link-layer header
  68  * for a "cooked" Linux capture, introduce a new DLT_ type (ask
  69  * "tcpdump-workers@lists.tcpdump.org" for one, so that you don't give it
  70  * a value that collides with a value already being used), and use the
  71  * new header in captures of that type, so that programs that can
  72  * handle DLT_LINUX_SLL captures will continue to handle them correctly
  73  * without any change, and so that capture files with different headers
  74  * can be told apart and programs that read them can dissect the
  75  * packets in them.
  76  *
  77  * This structure, and the #defines below, must be the same in the
  78  * libpcap and tcpdump versions of "sll.h".
  79  */
  80
  81 /*
  82  * A DLT_LINUX_SLL fake link-layer header.
  83  */
  84 #define SLL_HDR_LEN     16              /* total header length */
  85 #define SLL_ADDRLEN     8               /* length of address field */
  86
  87 struct sll_header {
  88         u_int16_t       sll_pkttype;    /* packet type */
  89         u_int16_t       sll_hatype;     /* link-layer address type */
  90         u_int16_t       sll_halen;      /* link-layer address length */
  91         u_int8_t        sll_addr[SLL_ADDRLEN];  /* link-layer address */
  92         u_int16_t       sll_protocol;   /* protocol */
  93 };
  94
  95 /*
  96  * The LINUX_SLL_ values for "sll_pkttype"; these correspond to the
  97  * PACKET_ values on Linux, but are defined here so that they're
  98  * available even on systems other than Linux, and so that they
  99  * don't change even if the PACKET_ values change.
 100  */
 101 #define LINUX_SLL_HOST          0
 102 #define LINUX_SLL_BROADCAST     1
 103 #define LINUX_SLL_MULTICAST     2
 104 #define LINUX_SLL_OTHERHOST     3
 105 #define LINUX_SLL_OUTGOING      4
 106
 107 /*
 108  * The LINUX_SLL_ values for "sll_protocol"; these correspond to the
 109  * ETH_P_ values on Linux, but are defined here so that they're
 110  * available even on systems other than Linux.  We assume, for now,
 111  * that the ETH_P_ values won't change in Linux; if they do, then:
 112  *
 113  *      if we don't translate them in "pcap-linux.c", capture files
 114  *      won't necessarily be readable if captured on a system that
 115  *      defines ETH_P_ values that don't match these values;
 116  *
 117  *      if we do translate them in "pcap-linux.c", that makes life
 118  *      unpleasant for the BPF code generator, as the values you test
 119  *      for in the kernel aren't the values that you test for when
 120  *      reading a capture file, so the fixup code run on BPF programs
 121  *      handed to the kernel ends up having to do more work.
 122  *
 123  * Add other values here as necessary, for handling packet types that
 124  * might show up on non-Ethernet, non-802.x networks.  (Not all the ones
 125  * in the Linux "if_ether.h" will, I suspect, actually show up in
 126  * captures.)
 127  */
 128 #define LINUX_SLL_P_802_3       0x0001  /* Novell 802.3 frames without 802.2 LLC header */
 129 #define LINUX_SLL_P_802_2       0x0004  /* 802.2 frames (not D/I/X Ethernet) */
 130
 131 static const struct tok sll_pkttype_values[] = {
 132     { LINUX_SLL_HOST, "In" },
 133     { LINUX_SLL_BROADCAST, "B" },
 134     { LINUX_SLL_MULTICAST, "M" },
 135     { LINUX_SLL_OTHERHOST, "P" },
 136     { LINUX_SLL_OUTGOING, "Out" },
 137     { 0, NULL}
 138 };
 139
 140 static inline void
 141 sll_print(register const struct sll_header *sllp, u_int length)
 142 {
 143         u_short ether_type;
 144
 145         printf("%3s ",tok2str(sll_pkttype_values,"?",EXTRACT_16BITS(&sllp->sll_pkttype)));
 146
 147         /*
 148          * XXX - check the link-layer address type value?
 149          * For now, we just assume 6 means Ethernet.
 150          * XXX - print others as strings of hex?
 151          */
 152         if (EXTRACT_16BITS(&sllp->sll_halen) == 6)
 153                 (void)printf("%s ", etheraddr_string(sllp->sll_addr));
 154
 155         if (!qflag) {
 156                 ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
 157
 158                 if (ether_type <= ETHERMTU) {
 159                         /*
 160                          * Not an Ethernet type; what type is it?
 161                          */
 162                         switch (ether_type) {
 163
 164                         case LINUX_SLL_P_802_3:
 165                                 /*
 166                                  * Ethernet_802.3 IPX frame.
 167                                  */
 168                                 (void)printf("802.3");
 169                                 break;
 170
 171                         case LINUX_SLL_P_802_2:
 172                                 /*
 173                                  * 802.2.
 174                                  */
 175                                 (void)printf("802.2");
 176                                 break;
 177
 178                         default:
 179                                 /*
 180                                  * What is it?
 181                                  */
 182                                 (void)printf("ethertype Unknown (0x%04x)",
 183                                     ether_type);
 184                                 break;
 185                         }
 186                 } else {
 187                         (void)printf("ethertype %s (0x%04x)",
 188                             tok2str(ethertype_values, "Unknown", ether_type),
 189                             ether_type);
 190                 }
 191                 (void)printf(", length %u: ", length);
 192         }
 193 }
 194
 195 /*
 196  * This is the top level routine of the printer.  'p' points to the
 197  * Linux "cooked capture" header of the packet, 'h->ts' is the timestamp,
 198  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
 199  * is the number of bytes actually captured.
 200  */
 201 u_int
 202 sll_if_print(const struct pcap_pkthdr *h, const u_char *p)
 203 {
 204         u_int caplen = h->caplen;
 205         u_int length = h->len;
 206         register const struct sll_header *sllp;
 207         u_short ether_type;
 208         u_short extracted_ethertype;
 209
 210         if (caplen < SLL_HDR_LEN) {
 211                 /*
 212                  * XXX - this "can't happen" because "pcap-linux.c" always
 213                  * adds this many bytes of header to every packet in a
 214                  * cooked socket capture.
 215                  */
 216                 printf("[|sll]");
 217                 return (caplen);
 218         }
 219
 220         sllp = (const struct sll_header *)p;
 221
 222         if (eflag)
 223                 sll_print(sllp, length);
 224
 225         /*
 226          * Go past the cooked-mode header.
 227          */
 228         length -= SLL_HDR_LEN;
 229         caplen -= SLL_HDR_LEN;
 230         p += SLL_HDR_LEN;
 231
 232         ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
 233
 234 recurse:
 235         /*
 236          * Is it (gag) an 802.3 encapsulation, or some non-Ethernet
 237          * packet type?
 238          */
 239         if (ether_type <= ETHERMTU) {
 240                 /*
 241                  * Yes - what type is it?
 242                  */
 243                 switch (ether_type) {
 244
 245                 case LINUX_SLL_P_802_3:
 246                         /*
 247                          * Ethernet_802.3 IPX frame.
 248                          */
 249                         ipx_print(p, length);
 250                         break;
 251
 252                 case LINUX_SLL_P_802_2:
 253                         /*
 254                          * 802.2.
 255                          * Try to print the LLC-layer header & higher layers.
 256                          */
 257                         if (llc_print(p, length, caplen, NULL, NULL,
 258                             &extracted_ethertype) == 0)
 259                                 goto unknown;   /* unknown LLC type */
 260                         break;
 261
 262                 default:
 263                         extracted_ethertype = 0;
 264                         /*FALLTHROUGH*/
 265
 266                 unknown:
 267                         /* ether_type not known, print raw packet */
 268                         if (!eflag)
 269                                 sll_print(sllp, length + SLL_HDR_LEN);
 270                         if (extracted_ethertype) {
 271                                 printf("(LLC %s) ",
 272                                etherproto_string(htons(extracted_ethertype)));
 273                         }
 274                         if (!suppress_default_print)
 275                                 default_print(p, caplen);
 276                         break;
 277                 }
 278         } else if (ether_type == ETHERTYPE_8021Q) {
 279                 /*
 280                  * Print VLAN information, and then go back and process
 281                  * the enclosed type field.
 282                  */
 283                 if (caplen < 4 || length < 4) {
 284                         printf("[|vlan]");
 285                         return (SLL_HDR_LEN);
 286                 }
 287                 if (eflag) {
 288                         u_int16_t tag = EXTRACT_16BITS(p);
 289
 290                         printf("vlan %u, p %u%s, ",
 291                             tag & 0xfff,
 292                             tag >> 13,
 293                             (tag & 0x1000) ? ", CFI" : "");
 294                 }
 295
 296                 ether_type = EXTRACT_16BITS(p + 2);
 297                 if (ether_type <= ETHERMTU)
 298                         ether_type = LINUX_SLL_P_802_2;
 299                 if (!qflag) {
 300                         (void)printf("ethertype %s, ",
 301                             tok2str(ethertype_values, "Unknown", ether_type));
 302                 }
 303                 p += 4;
 304                 length -= 4;
 305                 caplen -= 4;
 306                 goto recurse;
 307         } else {
 308                 if (ethertype_print(gndo, ether_type, p, length, caplen) == 0) {
 309                         /* ether_type not known, print raw packet */
 310                         if (!eflag)
 311                                 sll_print(sllp, length + SLL_HDR_LEN);
 312                         if (!suppress_default_print)
 313                                 default_print(p, caplen);
 314                 }
 315         }
 316
 317         return (SLL_HDR_LEN);
 318 }