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 /*
  36  * For captures on Linux cooked sockets, we construct a fake header
  37  * that includes:
  38  *
  39  *      a 2-byte "packet type" which is one of:
  40  *
  41  *              LINUX_SLL_HOST          packet was sent to us
  42  *              LINUX_SLL_BROADCAST     packet was broadcast
  43  *              LINUX_SLL_MULTICAST     packet was multicast
  44  *              LINUX_SLL_OTHERHOST     packet was sent to somebody else
  45  *              LINUX_SLL_OUTGOING      packet was sent *by* us;
  46  *
  47  *      a 2-byte Ethernet protocol field;
  48  *
  49  *      a 2-byte link-layer type;
  50  *
  51  *      a 2-byte link-layer address length;
  52  *
  53  *      an 8-byte source link-layer address, whose actual length is
  54  *      specified by the previous value.
  55  *
  56  * All fields except for the link-layer address are in network byte order.
  57  *
  58  * DO NOT change the layout of this structure, or change any of the
  59  * LINUX_SLL_ values below.  If you must change the link-layer header
  60  * for a "cooked" Linux capture, introduce a new DLT_ type (ask
  61  * "tcpdump-workers@lists.tcpdump.org" for one, so that you don't give it
  62  * a value that collides with a value already being used), and use the
  63  * new header in captures of that type, so that programs that can
  64  * handle DLT_LINUX_SLL captures will continue to handle them correctly
  65  * without any change, and so that capture files with different headers
  66  * can be told apart and programs that read them can dissect the
  67  * packets in them.
  68  *
  69  * This structure, and the #defines below, must be the same in the
  70  * libpcap and tcpdump versions of "sll.h".
  71  */
  72
  73 /*
  74  * A DLT_LINUX_SLL fake link-layer header.
  75  */
  76 #define SLL_HDR_LEN     16              /* total header length */
  77 #define SLL_ADDRLEN     8               /* length of address field */
  78
  79 struct sll_header {
  80         nd_uint16_t     sll_pkttype;    /* packet type */
  81         nd_uint16_t     sll_hatype;     /* link-layer address type */
  82         nd_uint16_t     sll_halen;      /* link-layer address length */
  83         nd_byte         sll_addr[SLL_ADDRLEN];  /* link-layer address */
  84         nd_uint16_t     sll_protocol;   /* protocol */
  85 };
  86
  87 /*
  88  * The LINUX_SLL_ values for "sll_pkttype"; these correspond to the
  89  * PACKET_ values on Linux, but are defined here so that they're
  90  * available even on systems other than Linux, and so that they
  91  * don't change even if the PACKET_ values change.
  92  */
  93 #define LINUX_SLL_HOST          0
  94 #define LINUX_SLL_BROADCAST     1
  95 #define LINUX_SLL_MULTICAST     2
  96 #define LINUX_SLL_OTHERHOST     3
  97 #define LINUX_SLL_OUTGOING      4
  98
  99 /*
 100  * The LINUX_SLL_ values for "sll_protocol"; these correspond to the
 101  * ETH_P_ values on Linux, but are defined here so that they're
 102  * available even on systems other than Linux.  We assume, for now,
 103  * that the ETH_P_ values won't change in Linux; if they do, then:
 104  *
 105  *      if we don't translate them in "pcap-linux.c", capture files
 106  *      won't necessarily be readable if captured on a system that
 107  *      defines ETH_P_ values that don't match these values;
 108  *
 109  *      if we do translate them in "pcap-linux.c", that makes life
 110  *      unpleasant for the BPF code generator, as the values you test
 111  *      for in the kernel aren't the values that you test for when
 112  *      reading a capture file, so the fixup code run on BPF programs
 113  *      handed to the kernel ends up having to do more work.
 114  *
 115  * Add other values here as necessary, for handling packet types that
 116  * might show up on non-Ethernet, non-802.x networks.  (Not all the ones
 117  * in the Linux "if_ether.h" will, I suspect, actually show up in
 118  * captures.)
 119  */
 120 #define LINUX_SLL_P_802_3       0x0001  /* Novell 802.3 frames without 802.2 LLC header */
 121 #define LINUX_SLL_P_802_2       0x0004  /* 802.2 frames (not D/I/X Ethernet) */
 122
 123 static const struct tok sll_pkttype_values[] = {
 124     { LINUX_SLL_HOST, "In" },
 125     { LINUX_SLL_BROADCAST, "B" },
 126     { LINUX_SLL_MULTICAST, "M" },
 127     { LINUX_SLL_OTHERHOST, "P" },
 128     { LINUX_SLL_OUTGOING, "Out" },
 129     { 0, NULL}
 130 };
 131
 132 static void
 133 sll_print(netdissect_options *ndo, const struct sll_header *sllp, u_int length)
 134 {
 135         u_short ether_type;
 136
 137         ndo->ndo_protocol = "sll";
 138         ND_PRINT("%3s ",tok2str(sll_pkttype_values,"?",EXTRACT_BE_U_2(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_BE_U_2(sllp->sll_halen) == 6)
 146                 ND_PRINT("%s ", etheraddr_string(ndo, sllp->sll_addr));
 147
 148         if (!ndo->ndo_qflag) {
 149                 ether_type = EXTRACT_BE_U_2(sllp->sll_protocol);
 150
 151                 if (ether_type <= MAX_ETHERNET_LENGTH_VAL) {
 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("802.3");
 162                                 break;
 163
 164                         case LINUX_SLL_P_802_2:
 165                                 /*
 166                                  * 802.2.
 167                                  */
 168                                 ND_PRINT("802.2");
 169                                 break;
 170
 171                         default:
 172                                 /*
 173                                  * What is it?
 174                                  */
 175                                 ND_PRINT("ethertype Unknown (0x%04x)",
 176                                     ether_type);
 177                                 break;
 178                         }
 179                 } else {
 180                         ND_PRINT("ethertype %s (0x%04x)",
 181                             tok2str(ethertype_values, "Unknown", ether_type),
 182                             ether_type);
 183                 }
 184                 ND_PRINT(", 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         const struct sll_header *sllp;
 200         u_short ether_type;
 201         int llc_hdrlen;
 202         u_int hdrlen;
 203
 204         ndo->ndo_protocol = "sll_if";
 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("[|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_BE_U_2(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 <= MAX_ETHERNET_LENGTH_VAL) {
 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("[|vlan]");
 275                         return (hdrlen + caplen);
 276                 }
 277                 if (length < 4) {
 278                         ND_PRINT("[|vlan]");
 279                         return (hdrlen + length);
 280                 }
 281                 if (ndo->ndo_eflag) {
 282                         uint16_t tag = EXTRACT_BE_U_2(p);
 283
 284                         ND_PRINT("%s, ", ieee8021q_tci_string(tag));
 285                 }
 286
 287                 ether_type = EXTRACT_BE_U_2(p + 2);
 288                 if (ether_type <= MAX_ETHERNET_LENGTH_VAL)
 289                         ether_type = LINUX_SLL_P_802_2;
 290                 if (!ndo->ndo_qflag) {
 291                         ND_PRINT("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 }