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 #define NETDISSECT_REWORKED
  23 #ifdef HAVE_CONFIG_H
  24 #include "config.h"
  25 #endif
  26
  27 #include <tcpdump-stdinc.h>
  28
  29 #include "interface.h"
  30 #include "addrtoname.h"
  31 #include "ethertype.h"
  32 #include "extract.h"
  33
  34 #include "ether.h"
  35
  36 /*
  37  * For captures on Linux cooked sockets, we construct a fake header
  38  * that includes:
  39  *
  40  *      a 2-byte "packet type" which is one of:
  41  *
  42  *              LINUX_SLL_HOST          packet was sent to us
  43  *              LINUX_SLL_BROADCAST     packet was broadcast
  44  *              LINUX_SLL_MULTICAST     packet was multicast
  45  *              LINUX_SLL_OTHERHOST     packet was sent to somebody else
  46  *              LINUX_SLL_OUTGOING      packet was sent *by* us;
  47  *
  48  *      a 2-byte Ethernet protocol field;
  49  *
  50  *      a 2-byte link-layer type;
  51  *
  52  *      a 2-byte link-layer address length;
  53  *
  54  *      an 8-byte source link-layer address, whose actual length is
  55  *      specified by the previous value.
  56  *
  57  * All fields except for the link-layer address are in network byte order.
  58  *
  59  * DO NOT change the layout of this structure, or change any of the
  60  * LINUX_SLL_ values below.  If you must change the link-layer header
  61  * for a "cooked" Linux capture, introduce a new DLT_ type (ask
  62  * "tcpdump-workers@lists.tcpdump.org" for one, so that you don't give it
  63  * a value that collides with a value already being used), and use the
  64  * new header in captures of that type, so that programs that can
  65  * handle DLT_LINUX_SLL captures will continue to handle them correctly
  66  * without any change, and so that capture files with different headers
  67  * can be told apart and programs that read them can dissect the
  68  * packets in them.
  69  *
  70  * This structure, and the #defines below, must be the same in the
  71  * libpcap and tcpdump versions of "sll.h".
  72  */
  73
  74 /*
  75  * A DLT_LINUX_SLL fake link-layer header.
  76  */
  77 #define SLL_HDR_LEN     16              /* total header length */
  78 #define SLL_ADDRLEN     8               /* length of address field */
  79
  80 struct sll_header {
  81         uint16_t        sll_pkttype;    /* packet type */
  82         uint16_t        sll_hatype;     /* link-layer address type */
  83         uint16_t        sll_halen;      /* link-layer address length */
  84         uint8_t         sll_addr[SLL_ADDRLEN];  /* link-layer address */
  85         uint16_t        sll_protocol;   /* protocol */
  86 };
  87
  88 /*
  89  * The LINUX_SLL_ values for "sll_pkttype"; these correspond to the
  90  * PACKET_ values on Linux, but are defined here so that they're
  91  * available even on systems other than Linux, and so that they
  92  * don't change even if the PACKET_ values change.
  93  */
  94 #define LINUX_SLL_HOST          0
  95 #define LINUX_SLL_BROADCAST     1
  96 #define LINUX_SLL_MULTICAST     2
  97 #define LINUX_SLL_OTHERHOST     3
  98 #define LINUX_SLL_OUTGOING      4
  99
 100 /*
 101  * The LINUX_SLL_ values for "sll_protocol"; these correspond to the
 102  * ETH_P_ values on Linux, but are defined here so that they're
 103  * available even on systems other than Linux.  We assume, for now,
 104  * that the ETH_P_ values won't change in Linux; if they do, then:
 105  *
 106  *      if we don't translate them in "pcap-linux.c", capture files
 107  *      won't necessarily be readable if captured on a system that
 108  *      defines ETH_P_ values that don't match these values;
 109  *
 110  *      if we do translate them in "pcap-linux.c", that makes life
 111  *      unpleasant for the BPF code generator, as the values you test
 112  *      for in the kernel aren't the values that you test for when
 113  *      reading a capture file, so the fixup code run on BPF programs
 114  *      handed to the kernel ends up having to do more work.
 115  *
 116  * Add other values here as necessary, for handling packet types that
 117  * might show up on non-Ethernet, non-802.x networks.  (Not all the ones
 118  * in the Linux "if_ether.h" will, I suspect, actually show up in
 119  * captures.)
 120  */
 121 #define LINUX_SLL_P_802_3       0x0001  /* Novell 802.3 frames without 802.2 LLC header */
 122 #define LINUX_SLL_P_802_2       0x0004  /* 802.2 frames (not D/I/X Ethernet) */
 123
 124 static const struct tok sll_pkttype_values[] = {
 125     { LINUX_SLL_HOST, "In" },
 126     { LINUX_SLL_BROADCAST, "B" },
 127     { LINUX_SLL_MULTICAST, "M" },
 128     { LINUX_SLL_OTHERHOST, "P" },
 129     { LINUX_SLL_OUTGOING, "Out" },
 130     { 0, NULL}
 131 };
 132
 133 static inline void
 134 sll_print(netdissect_options *ndo, register const struct sll_header *sllp, u_int length)
 135 {
 136         u_short ether_type;
 137
 138         ND_PRINT((ndo, "%3s ",tok2str(sll_pkttype_values,"?",EXTRACT_16BITS(&sllp->sll_pkttype))));
 139
 140         /*
 141          * XXX - check the link-layer address type value?
 142          * For now, we just assume 6 means Ethernet.
 143          * XXX - print others as strings of hex?
 144          */
 145         if (EXTRACT_16BITS(&sllp->sll_halen) == 6)
 146                 ND_PRINT((ndo, "%s ", etheraddr_string(ndo, sllp->sll_addr)));
 147
 148         if (!ndo->ndo_qflag) {
 149                 ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
 150
 151                 if (ether_type <= ETHERMTU) {
 152                         /*
 153                          * Not an Ethernet type; what type is it?
 154                          */
 155                         switch (ether_type) {
 156
 157                         case LINUX_SLL_P_802_3:
 158                                 /*
 159                                  * Ethernet_802.3 IPX frame.
 160                                  */
 161                                 ND_PRINT((ndo, "802.3"));
 162                                 break;
 163
 164                         case LINUX_SLL_P_802_2:
 165                                 /*
 166                                  * 802.2.
 167                                  */
 168                                 ND_PRINT((ndo, "802.2"));
 169                                 break;
 170
 171                         default:
 172                                 /*
 173                                  * What is it?
 174                                  */
 175                                 ND_PRINT((ndo, "ethertype Unknown (0x%04x)",
 176                                     ether_type));
 177                                 break;
 178                         }
 179                 } else {
 180                         ND_PRINT((ndo, "ethertype %s (0x%04x)",
 181                             tok2str(ethertype_values, "Unknown", ether_type),
 182                             ether_type));
 183                 }
 184                 ND_PRINT((ndo, ", length %u: ", length));
 185         }
 186 }
 187
 188 /*
 189  * This is the top level routine of the printer.  'p' points to the
 190  * Linux "cooked capture" header of the packet, 'h->ts' is the timestamp,
 191  * 'h->len' is the length of the packet off the wire, and 'h->caplen'
 192  * is the number of bytes actually captured.
 193  */
 194 u_int
 195 sll_if_print(netdissect_options *ndo, const struct pcap_pkthdr *h, const u_char *p)
 196 {
 197         u_int caplen = h->caplen;
 198         u_int length = h->len;
 199         register const struct sll_header *sllp;
 200         u_short ether_type;
 201         u_short extracted_ethertype;
 202
 203         if (caplen < SLL_HDR_LEN) {
 204                 /*
 205                  * XXX - this "can't happen" because "pcap-linux.c" always
 206                  * adds this many bytes of header to every packet in a
 207                  * cooked socket capture.
 208                  */
 209                 ND_PRINT((ndo, "[|sll]"));
 210                 return (caplen);
 211         }
 212
 213         sllp = (const struct sll_header *)p;
 214
 215         if (ndo->ndo_eflag)
 216                 sll_print(ndo, sllp, length);
 217
 218         /*
 219          * Go past the cooked-mode header.
 220          */
 221         length -= SLL_HDR_LEN;
 222         caplen -= SLL_HDR_LEN;
 223         p += SLL_HDR_LEN;
 224
 225         ether_type = EXTRACT_16BITS(&sllp->sll_protocol);
 226
 227 recurse:
 228         /*
 229          * Is it (gag) an 802.3 encapsulation, or some non-Ethernet
 230          * packet type?
 231          */
 232         if (ether_type <= ETHERMTU) {
 233                 /*
 234                  * Yes - what type is it?
 235                  */
 236                 switch (ether_type) {
 237
 238                 case LINUX_SLL_P_802_3:
 239                         /*
 240                          * Ethernet_802.3 IPX frame.
 241                          */
 242                         ipx_print(ndo, p, length);
 243                         break;
 244
 245                 case LINUX_SLL_P_802_2:
 246                         /*
 247                          * 802.2.
 248                          * Try to print the LLC-layer header & higher layers.
 249                          */
 250                         if (llc_print(ndo, p, length, caplen, NULL, NULL,
 251                             &extracted_ethertype) == 0)
 252                                 goto unknown;   /* unknown LLC type */
 253                         break;
 254
 255                 default:
 256                         extracted_ethertype = 0;
 257                         /*FALLTHROUGH*/
 258
 259                 unknown:
 260                         /* ether_type not known, print raw packet */
 261                         if (!ndo->ndo_eflag)
 262                                 sll_print(ndo, sllp, length + SLL_HDR_LEN);
 263                         if (extracted_ethertype) {
 264                                 ND_PRINT((ndo, "(LLC %s) ",
 265                                etherproto_string(htons(extracted_ethertype))));
 266                         }
 267                         if (!ndo->ndo_suppress_default_print)
 268                                 ND_DEFAULTPRINT(p, caplen);
 269                         break;
 270                 }
 271         } else if (ether_type == ETHERTYPE_8021Q) {
 272                 /*
 273                  * Print VLAN information, and then go back and process
 274                  * the enclosed type field.
 275                  */
 276                 if (caplen < 4 || length < 4) {
 277                         ND_PRINT((ndo, "[|vlan]"));
 278                         return (SLL_HDR_LEN);
 279                 }
 280                 if (ndo->ndo_eflag) {
 281                         uint16_t tag = EXTRACT_16BITS(p);
 282
 283                         ND_PRINT((ndo, "%s, ", ieee8021q_tci_string(tag)));
 284                 }
 285
 286                 ether_type = EXTRACT_16BITS(p + 2);
 287                 if (ether_type <= ETHERMTU)
 288                         ether_type = LINUX_SLL_P_802_2;
 289                 if (!ndo->ndo_qflag) {
 290                         ND_PRINT((ndo, "ethertype %s, ",
 291                             tok2str(ethertype_values, "Unknown", ether_type)));
 292                 }
 293                 p += 4;
 294                 length -= 4;
 295                 caplen -= 4;
 296                 goto recurse;
 297         } else {
 298                 if (ethertype_print(ndo, ether_type, p, length, caplen) == 0) {
 299                         /* ether_type not known, print raw packet */
 300                         if (!ndo->ndo_eflag)
 301                                 sll_print(ndo, sllp, length + SLL_HDR_LEN);
 302                         if (!ndo->ndo_suppress_default_print)
 303                                 ND_DEFAULTPRINT(p, caplen);
 304                 }
 305         }
 306
 307         return (SLL_HDR_LEN);
 308 }