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