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 (at) 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 } 311
