contrib/tcpdump/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 ether_type;
 202         int llc_hdrlen;
 203         u_int hdrlen;
 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                 ND_PRINT((ndo, "[|sll]"));
 212                 return (caplen);
 213         }
 214
 215         sllp = (const struct sll_header *)p;
 216
 217         if (ndo->ndo_eflag)
 218                 sll_print(ndo, 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         hdrlen = 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(ndo, 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                         llc_hdrlen = llc_print(ndo, p, length, caplen, NULL, NULL);
 254                         if (llc_hdrlen < 0)
 255                                 goto unknown;   /* unknown LLC type */
 256                         hdrlen += llc_hdrlen;
 257                         break;
 258
 259                 default:
 260                         /*FALLTHROUGH*/
 261
 262                 unknown:
 263                         /* packet type not known, print raw packet */
 264                         if (!ndo->ndo_suppress_default_print)
 265                                 ND_DEFAULTPRINT(p, caplen);
 266                         break;
 267                 }
 268         } else if (ether_type == ETHERTYPE_8021Q) {
 269                 /*
 270                  * Print VLAN information, and then go back and process
 271                  * the enclosed type field.
 272                  */
 273                 if (caplen < 4) {
 274                         ND_PRINT((ndo, "[|vlan]"));
 275                         return (hdrlen + caplen);
 276                 }
 277                 if (length < 4) {
 278                         ND_PRINT((ndo, "[|vlan]"));
 279                         return (hdrlen + length);
 280                 }
 281                 if (ndo->ndo_eflag) {
 282                         uint16_t tag = EXTRACT_16BITS(p);
 283
 284                         ND_PRINT((ndo, "%s, ", ieee8021q_tci_string(tag)));
 285                 }
 286
 287                 ether_type = EXTRACT_16BITS(p + 2);
 288                 if (ether_type <= ETHERMTU)
 289                         ether_type = LINUX_SLL_P_802_2;
 290                 if (!ndo->ndo_qflag) {
 291                         ND_PRINT((ndo, "ethertype %s, ",
 292                             tok2str(ethertype_values, "Unknown", ether_type)));
 293                 }
 294                 p += 4;
 295                 length -= 4;
 296                 caplen -= 4;
 297                 hdrlen += 4;
 298                 goto recurse;
 299         } else {
 300                 if (ethertype_print(ndo, ether_type, p, length, caplen, NULL, NULL) == 0) {
 301                         /* ether_type not known, print raw packet */
 302                         if (!ndo->ndo_eflag)
 303                                 sll_print(ndo, sllp, length + SLL_HDR_LEN);
 304                         if (!ndo->ndo_suppress_default_print)
 305                                 ND_DEFAULTPRINT(p, caplen);
 306                 }
 307         }
 308
 309         return (hdrlen);
 310 }