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