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 /* \summary: Linux cooked sockets capture printer */
  23
  24 #ifdef HAVE_CONFIG_H
  25 #include "config.h"
  26 #endif
  27
  28 #include <netdissect-stdinc.h>
  29
  30 #include "netdissect.h"
  31 #include "addrtoname.h"
  32 #include "ethertype.h"
  33 #include "extract.h"
  34
  35 #include "ether.h"
  36
  37 /*
  38  * For captures on Linux cooked sockets, we construct a fake header
  39  * that includes:
  40  *
  41  *      a 2-byte "packet type" which is one of:
  42  *
  43  *              LINUX_SLL_HOST          packet was sent to us
  44  *              LINUX_SLL_BROADCAST     packet was broadcast
  45  *              LINUX_SLL_MULTICAST     packet was multicast
  46  *              LINUX_SLL_OTHERHOST     packet was sent to somebody else
  47  *              LINUX_SLL_OUTGOING      packet was sent *by* us;
  48  *
  49  *      a 2-byte Ethernet protocol field;
  50  *
  51  *      a 2-byte link-layer type;
  52  *
  53  *      a 2-byte link-layer address length;
  54  *
  55  *      an 8-byte source link-layer address, whose actual length is
  56  *      specified by the previous value.
  57  *
  58  * All fields except for the link-layer address are in network byte order.
  59  *
  60  * DO NOT change the layout of this structure, or change any of the
  61  * LINUX_SLL_ values below.  If you must change the link-layer header
  62  * for a "cooked" Linux capture, introduce a new DLT_ type (ask
  63  * "tcpdump-workers@lists.tcpdump.org" for one, so that you don't give it
  64  * a value that collides with a value already being used), and use the
  65  * new header in captures of that type, so that programs that can
  66  * handle DLT_LINUX_SLL captures will continue to handle them correctly
  67  * without any change, and so that capture files with different headers
  68  * can be told apart and programs that read them can dissect the
  69  * packets in them.
  70  *
  71  * This structure, and the #defines below, must be the same in the
  72  * libpcap and tcpdump versions of "sll.h".
  73  */
  74
  75 /*
  76  * A DLT_LINUX_SLL fake link-layer header.
  77  */
  78 #define SLL_HDR_LEN     16              /* total header length */
  79 #define SLL_ADDRLEN     8               /* length of address field */
  80
  81 struct sll_header {
  82         uint16_t        sll_pkttype;    /* packet type */
  83         uint16_t        sll_hatype;     /* link-layer address type */
  84         uint16_t        sll_halen;      /* link-layer address length */
  85         uint8_t         sll_addr[SLL_ADDRLEN];  /* link-layer address */
  86         uint16_t        sll_protocol;   /* protocol */
  87 };
  88
  89 /*
  90  * The LINUX_SLL_ values for "sll_pkttype"; these correspond to the
  91  * PACKET_ values on Linux, but are defined here so that they're
  92  * available even on systems other than Linux, and so that they
  93  * don't change even if the PACKET_ values change.
  94  */
  95 #define LINUX_SLL_HOST          0
  96 #define LINUX_SLL_BROADCAST     1
  97 #define LINUX_SLL_MULTICAST     2
  98 #define LINUX_SLL_OTHERHOST     3
  99 #define LINUX_SLL_OUTGOING      4
 100
 101 /*
 102  * The LINUX_SLL_ values for "sll_protocol"; these correspond to the
 103  * ETH_P_ values on Linux, but are defined here so that they're
 104  * available even on systems other than Linux.  We assume, for now,
 105  * that the ETH_P_ values won't change in Linux; if they do, then:
 106  *
 107  *      if we don't translate them in "pcap-linux.c", capture files
 108  *      won't necessarily be readable if captured on a system that
 109  *      defines ETH_P_ values that don't match these values;
 110  *
 111  *      if we do translate them in "pcap-linux.c", that makes life
 112  *      unpleasant for the BPF code generator, as the values you test
 113  *      for in the kernel aren't the values that you test for when
 114  *      reading a capture file, so the fixup code run on BPF programs
 115  *      handed to the kernel ends up having to do more work.
 116  *
 117  * Add other values here as necessary, for handling packet types that
 118  * might show up on non-Ethernet, non-802.x networks.  (Not all the ones
 119  * in the Linux "if_ether.h" will, I suspect, actually show up in
 120  * captures.)
 121  */
 122 #define LINUX_SLL_P_802_3       0x0001  /* Novell 802.3 frames without 802.2 LLC header */
 123 #define LINUX_SLL_P_802_2       0x0004  /* 802.2 frames (not D/I/X Ethernet) */
 124
 125 static const struct tok sll_pkttype_values[] = {
 126     { LINUX_SLL_HOST, "In" },
 127     { LINUX_SLL_BROADCAST, "B" },
 128     { LINUX_SLL_MULTICAST, "M" },
 129     { LINUX_SLL_OTHERHOST, "P" },
 130     { LINUX_SLL_OUTGOING, "Out" },
 131     { 0, NULL}
 132 };
 133
 134 static inline void
 135 sll_print(netdissect_options *ndo, register const struct sll_header *sllp, u_int length)
 136 {
 137         u_short ether_type;
 138
 139         ND_PRINT((ndo, "%3s ",tok2str(sll_pkttype_values,"?",EXTRACT_16BITS(&sllp->sll_pkttype))));
 140
 141         /*
 142          * XXX - check the link-layer address type value?
 143          * For now, we just assume 6 means Ethernet.
 144          * XXX - print others as strings of hex?
 145          */
 146         if (EXTRACT_16BITS(&sllp->sll_halen) == 6)
 147                 ND_PRINT((ndo, "%s ", etheraddr_string(ndo, sllp->sll_addr)));
 148
 149         if (!ndo->ndo_qflag) {
 150                 ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
 151
 152                 if (ether_type <= ETHERMTU) {
 153                         /*
 154                          * Not an Ethernet type; what type is it?
 155                          */
 156                         switch (ether_type) {
 157
 158                         case LINUX_SLL_P_802_3:
 159                                 /*
 160                                  * Ethernet_802.3 IPX frame.
 161                                  */
 162                                 ND_PRINT((ndo, "802.3"));
 163                                 break;
 164
 165                         case LINUX_SLL_P_802_2:
 166                                 /*
 167                                  * 802.2.
 168                                  */
 169                                 ND_PRINT((ndo, "802.2"));
 170                                 break;
 171
 172                         default:
 173                                 /*
 174                                  * What is it?
 175                                  */
 176                                 ND_PRINT((ndo, "ethertype Unknown (0x%04x)",
 177                                     ether_type));
 178                                 break;
 179                         }
 180                 } else {
 181                         ND_PRINT((ndo, "ethertype %s (0x%04x)",
 182                             tok2str(ethertype_values, "Unknown", ether_type),
 183                             ether_type));
 184                 }
 185                 ND_PRINT((ndo, ", length %u: ", length));
 186         }
 187 }
 188
 189 /*
 190  * This is the top level routine of the printer.  'p' points to the
 191  * Linux "cooked capture" header of the packet, 'h->ts' is the timestamp,
 192  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
 193  * is the number of bytes actually captured.
 194  */
 195 u_int
 196 sll_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
 197 {
 198         u_int caplen = h->caplen;
 199         u_int length = h->len;
 200         register const struct sll_header *sllp;
 201         u_short hatype;
 202         u_short ether_type;
 203         int llc_hdrlen;
 204         u_int hdrlen;
 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                 ND_PRINT((ndo, "[|sll]"));
 213                 return (caplen);
 214         }
 215
 216         sllp = (const struct sll_header *)p;
 217
 218         if (ndo->ndo_eflag)
 219                 sll_print(ndo, 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         hdrlen = SLL_HDR_LEN;
 228
 229         hatype = EXTRACT_16BITS(&sllp->sll_hatype);
 230         switch (hatype) {
 231
 232         case 803:
 233                 /*
 234                  * This is an packet with a radiotap header;
 235                  * just dissect the payload as such.
 236                  */
 237                 return (SLL_HDR_LEN + ieee802_11_radio_print(ndo, p, length, caplen));
 238         }
 239         ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
 240
 241 recurse:
 242         /*
 243          * Is it (gag) an 802.3 encapsulation, or some non-Ethernet
 244          * packet type?
 245          */
 246         if (ether_type <= ETHERMTU) {
 247                 /*
 248                  * Yes - what type is it?
 249                  */
 250                 switch (ether_type) {
 251
 252                 case LINUX_SLL_P_802_3:
 253                         /*
 254                          * Ethernet_802.3 IPX frame.
 255                          */
 256                         ipx_print(ndo, p, length);
 257                         break;
 258
 259                 case LINUX_SLL_P_802_2:
 260                         /*
 261                          * 802.2.
 262                          * Try to print the LLC-layer header & higher layers.
 263                          */
 264                         llc_hdrlen = llc_print(ndo, p, length, caplen, NULL, NULL);
 265                         if (llc_hdrlen < 0)
 266                                 goto unknown;   /* unknown LLC type */
 267                         hdrlen += llc_hdrlen;
 268                         break;
 269
 270                 default:
 271                         /*FALLTHROUGH*/
 272
 273                 unknown:
 274                         /* packet type not known, print raw packet */
 275                         if (!ndo->ndo_suppress_default_print)
 276                                 ND_DEFAULTPRINT(p, caplen);
 277                         break;
 278                 }
 279         } else if (ether_type == ETHERTYPE_8021Q) {
 280                 /*
 281                  * Print VLAN information, and then go back and process
 282                  * the enclosed type field.
 283                  */
 284                 if (caplen < 4) {
 285                         ND_PRINT((ndo, "[|vlan]"));
 286                         return (hdrlen + caplen);
 287                 }
 288                 if (length < 4) {
 289                         ND_PRINT((ndo, "[|vlan]"));
 290                         return (hdrlen + length);
 291                 }
 292                 if (ndo->ndo_eflag) {
 293                         uint16_t tag = EXTRACT_16BITS(p);
 294
 295                         ND_PRINT((ndo, "%s, ", ieee8021q_tci_string(tag)));
 296                 }
 297
 298                 ether_type = EXTRACT_16BITS(p + 2);
 299                 if (ether_type <= ETHERMTU)
 300                         ether_type = LINUX_SLL_P_802_2;
 301                 if (!ndo->ndo_qflag) {
 302                         ND_PRINT((ndo, "ethertype %s, ",
 303                             tok2str(ethertype_values, "Unknown", ether_type)));
 304                 }
 305                 p += 4;
 306                 length -= 4;
 307                 caplen -= 4;
 308                 hdrlen += 4;
 309                 goto recurse;
 310         } else {
 311                 if (ethertype_print(ndo, ether_type, p, length, caplen, NULL, NULL) == 0) {
 312                         /* ether_type not known, print raw packet */
 313                         if (!ndo->ndo_eflag)
 314                                 sll_print(ndo, sllp, length + SLL_HDR_LEN);
 315                         if (!ndo->ndo_suppress_default_print)
 316                                 ND_DEFAULTPRINT(p, caplen);
 317                 }
 318         }
 319
 320         return (hdrlen);
 321 }