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      1 /*
      2  *  pcap-linux.c: Packet capture interface to the Linux kernel
      3  *
      4  *  Copyright (c) 2000 Torsten Landschoff <torsten (at) debian.org>
      5  *  		       Sebastian Krahmer  <krahmer (at) cs.uni-potsdam.de>
      6  *
      7  *  License: BSD
      8  *
      9  *  Redistribution and use in source and binary forms, with or without
     10  *  modification, are permitted provided that the following conditions
     11  *  are met:
     12  *
     13  *  1. Redistributions of source code must retain the above copyright
     14  *     notice, this list of conditions and the following disclaimer.
     15  *  2. Redistributions in binary form must reproduce the above copyright
     16  *     notice, this list of conditions and the following disclaimer in
     17  *     the documentation and/or other materials provided with the
     18  *     distribution.
     19  *  3. The names of the authors may not be used to endorse or promote
     20  *     products derived from this software without specific prior
     21  *     written permission.
     22  *
     23  *  THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
     24  *  IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
     25  *  WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
     26  */
     27 
     28 #ifndef lint
     29 static const char rcsid[] _U_ =
     30     "@(#) $Header: /tcpdump/master/libpcap/pcap-linux.c,v 1.110.2.14 2006/10/12 17:26:58 guy Exp $ (LBL)";
     31 #endif
     32 
     33 /*
     34  * Known problems with 2.0[.x] kernels:
     35  *
     36  *   - The loopback device gives every packet twice; on 2.2[.x] kernels,
     37  *     if we use PF_PACKET, we can filter out the transmitted version
     38  *     of the packet by using data in the "sockaddr_ll" returned by
     39  *     "recvfrom()", but, on 2.0[.x] kernels, we have to use
     40  *     PF_INET/SOCK_PACKET, which means "recvfrom()" supplies a
     41  *     "sockaddr_pkt" which doesn't give us enough information to let
     42  *     us do that.
     43  *
     44  *   - We have to set the interface's IFF_PROMISC flag ourselves, if
     45  *     we're to run in promiscuous mode, which means we have to turn
     46  *     it off ourselves when we're done; the kernel doesn't keep track
     47  *     of how many sockets are listening promiscuously, which means
     48  *     it won't get turned off automatically when no sockets are
     49  *     listening promiscuously.  We catch "pcap_close()" and, for
     50  *     interfaces we put into promiscuous mode, take them out of
     51  *     promiscuous mode - which isn't necessarily the right thing to
     52  *     do, if another socket also requested promiscuous mode between
     53  *     the time when we opened the socket and the time when we close
     54  *     the socket.
     55  *
     56  *   - MSG_TRUNC isn't supported, so you can't specify that "recvfrom()"
     57  *     return the amount of data that you could have read, rather than
     58  *     the amount that was returned, so we can't just allocate a buffer
     59  *     whose size is the snapshot length and pass the snapshot length
     60  *     as the byte count, and also pass MSG_TRUNC, so that the return
     61  *     value tells us how long the packet was on the wire.
     62  *
     63  *     This means that, if we want to get the actual size of the packet,
     64  *     so we can return it in the "len" field of the packet header,
     65  *     we have to read the entire packet, not just the part that fits
     66  *     within the snapshot length, and thus waste CPU time copying data
     67  *     from the kernel that our caller won't see.
     68  *
     69  *     We have to get the actual size, and supply it in "len", because
     70  *     otherwise, the IP dissector in tcpdump, for example, will complain
     71  *     about "truncated-ip", as the packet will appear to have been
     72  *     shorter, on the wire, than the IP header said it should have been.
     73  */
     74 
     75 
     76 #include <stdlib.h>
     77 #ifdef HAVE_CONFIG_H
     78 #include "config.h"
     79 #endif
     80 
     81 #include "pcap-int.h"
     82 #include "sll.h"
     83 
     84 #ifdef HAVE_DAG_API
     85 #include "pcap-dag.h"
     86 #endif /* HAVE_DAG_API */
     87 
     88 #ifdef HAVE_SEPTEL_API
     89 #include "pcap-septel.h"
     90 #endif /* HAVE_SEPTEL_API */
     91 
     92 #include <errno.h>
     93 #include <unistd.h>
     94 #include <fcntl.h>
     95 #include <string.h>
     96 #include <sys/socket.h>
     97 #include <sys/ioctl.h>
     98 #include <sys/utsname.h>
     99 #include <net/if.h>
    100 #include <netinet/in.h>
    101 #include <linux/if_ether.h>
    102 #include <net/if_arp.h>
    103 
    104 /*
    105  * If PF_PACKET is defined, we can use {SOCK_RAW,SOCK_DGRAM}/PF_PACKET
    106  * sockets rather than SOCK_PACKET sockets.
    107  *
    108  * To use them, we include <linux/if_packet.h> rather than
    109  * <netpacket/packet.h>; we do so because
    110  *
    111  *	some Linux distributions (e.g., Slackware 4.0) have 2.2 or
    112  *	later kernels and libc5, and don't provide a <netpacket/packet.h>
    113  *	file;
    114  *
    115  *	not all versions of glibc2 have a <netpacket/packet.h> file
    116  *	that defines stuff needed for some of the 2.4-or-later-kernel
    117  *	features, so if the system has a 2.4 or later kernel, we
    118  *	still can't use those features.
    119  *
    120  * We're already including a number of other <linux/XXX.h> headers, and
    121  * this code is Linux-specific (no other OS has PF_PACKET sockets as
    122  * a raw packet capture mechanism), so it's not as if you gain any
    123  * useful portability by using <netpacket/packet.h>
    124  *
    125  * XXX - should we just include <linux/if_packet.h> even if PF_PACKET
    126  * isn't defined?  It only defines one data structure in 2.0.x, so
    127  * it shouldn't cause any problems.
    128  */
    129 #ifdef PF_PACKET
    130 # include <linux/if_packet.h>
    131 
    132  /*
    133   * On at least some Linux distributions (for example, Red Hat 5.2),
    134   * there's no <netpacket/packet.h> file, but PF_PACKET is defined if
    135   * you include <sys/socket.h>, but <linux/if_packet.h> doesn't define
    136   * any of the PF_PACKET stuff such as "struct sockaddr_ll" or any of
    137   * the PACKET_xxx stuff.
    138   *
    139   * So we check whether PACKET_HOST is defined, and assume that we have
    140   * PF_PACKET sockets only if it is defined.
    141   */
    142 # ifdef PACKET_HOST
    143 #  define HAVE_PF_PACKET_SOCKETS
    144 # endif /* PACKET_HOST */
    145 #endif /* PF_PACKET */
    146 
    147 #ifdef SO_ATTACH_FILTER
    148 #include <linux/types.h>
    149 #include <linux/filter.h>
    150 #endif
    151 
    152 #ifndef __GLIBC__
    153 typedef int		socklen_t;
    154 #endif
    155 
    156 #ifndef MSG_TRUNC
    157 /*
    158  * This is being compiled on a system that lacks MSG_TRUNC; define it
    159  * with the value it has in the 2.2 and later kernels, so that, on
    160  * those kernels, when we pass it in the flags argument to "recvfrom()"
    161  * we're passing the right value and thus get the MSG_TRUNC behavior
    162  * we want.  (We don't get that behavior on 2.0[.x] kernels, because
    163  * they didn't support MSG_TRUNC.)
    164  */
    165 #define MSG_TRUNC	0x20
    166 #endif
    167 
    168 #ifndef SOL_PACKET
    169 /*
    170  * This is being compiled on a system that lacks SOL_PACKET; define it
    171  * with the value it has in the 2.2 and later kernels, so that we can
    172  * set promiscuous mode in the good modern way rather than the old
    173  * 2.0-kernel crappy way.
    174  */
    175 #define SOL_PACKET	263
    176 #endif
    177 
    178 #define MAX_LINKHEADER_SIZE	256
    179 
    180 /*
    181  * When capturing on all interfaces we use this as the buffer size.
    182  * Should be bigger then all MTUs that occur in real life.
    183  * 64kB should be enough for now.
    184  */
    185 #define BIGGER_THAN_ALL_MTUS	(64*1024)
    186 
    187 /*
    188  * Prototypes for internal functions
    189  */
    190 static void map_arphrd_to_dlt(pcap_t *, int, int);
    191 static int live_open_old(pcap_t *, const char *, int, int, char *);
    192 static int live_open_new(pcap_t *, const char *, int, int, char *);
    193 static int pcap_read_linux(pcap_t *, int, pcap_handler, u_char *);
    194 static int pcap_read_packet(pcap_t *, pcap_handler, u_char *);
    195 static int pcap_inject_linux(pcap_t *, const void *, size_t);
    196 static int pcap_stats_linux(pcap_t *, struct pcap_stat *);
    197 static int pcap_setfilter_linux(pcap_t *, struct bpf_program *);
    198 static int pcap_setdirection_linux(pcap_t *, pcap_direction_t);
    199 static void pcap_close_linux(pcap_t *);
    200 
    201 /*
    202  * Wrap some ioctl calls
    203  */
    204 #ifdef HAVE_PF_PACKET_SOCKETS
    205 static int	iface_get_id(int fd, const char *device, char *ebuf);
    206 #endif
    207 static int	iface_get_mtu(int fd, const char *device, char *ebuf);
    208 static int 	iface_get_arptype(int fd, const char *device, char *ebuf);
    209 #ifdef HAVE_PF_PACKET_SOCKETS
    210 static int 	iface_bind(int fd, int ifindex, char *ebuf);
    211 #endif
    212 static int 	iface_bind_old(int fd, const char *device, char *ebuf);
    213 
    214 #ifdef SO_ATTACH_FILTER
    215 static int	fix_program(pcap_t *handle, struct sock_fprog *fcode);
    216 static int	fix_offset(struct bpf_insn *p);
    217 static int	set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode);
    218 static int	reset_kernel_filter(pcap_t *handle);
    219 
    220 static struct sock_filter	total_insn
    221 	= BPF_STMT(BPF_RET | BPF_K, 0);
    222 static struct sock_fprog	total_fcode
    223 	= { 1, &total_insn };
    224 #endif
    225 
    226 /*
    227  *  Get a handle for a live capture from the given device. You can
    228  *  pass NULL as device to get all packages (without link level
    229  *  information of course). If you pass 1 as promisc the interface
    230  *  will be set to promiscous mode (XXX: I think this usage should
    231  *  be deprecated and functions be added to select that later allow
    232  *  modification of that values -- Torsten).
    233  *
    234  *  See also pcap(3).
    235  */
    236 pcap_t *
    237 pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
    238     char *ebuf)
    239 {
    240 	pcap_t		*handle;
    241 	int		mtu;
    242 	int		err;
    243 	int		live_open_ok = 0;
    244 	struct utsname	utsname;
    245 
    246 #ifdef HAVE_DAG_API
    247 	if (strstr(device, "dag")) {
    248 		return dag_open_live(device, snaplen, promisc, to_ms, ebuf);
    249 	}
    250 #endif /* HAVE_DAG_API */
    251 
    252 #ifdef HAVE_SEPTEL_API
    253 	if (strstr(device, "septel")) {
    254 		return septel_open_live(device, snaplen, promisc, to_ms, ebuf);
    255 	}
    256 #endif /* HAVE_SEPTEL_API */
    257 
    258 	/* Allocate a handle for this session. */
    259 
    260 	handle = malloc(sizeof(*handle));
    261 	if (handle == NULL) {
    262 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "malloc: %s",
    263 			 pcap_strerror(errno));
    264 		return NULL;
    265 	}
    266 
    267 	/* Initialize some components of the pcap structure. */
    268 
    269 	memset(handle, 0, sizeof(*handle));
    270 	handle->snapshot	= snaplen;
    271 	handle->md.timeout	= to_ms;
    272 
    273 	/*
    274 	 * NULL and "any" are special devices which give us the hint to
    275 	 * monitor all devices.
    276 	 */
    277 	if (!device || strcmp(device, "any") == 0) {
    278 		device			= NULL;
    279 		handle->md.device	= strdup("any");
    280 		if (promisc) {
    281 			promisc = 0;
    282 			/* Just a warning. */
    283 			snprintf(ebuf, PCAP_ERRBUF_SIZE,
    284 			    "Promiscuous mode not supported on the \"any\" device");
    285 		}
    286 
    287 	} else
    288 		handle->md.device	= strdup(device);
    289 
    290 	if (handle->md.device == NULL) {
    291 		snprintf(ebuf, PCAP_ERRBUF_SIZE, "strdup: %s",
    292 			 pcap_strerror(errno) );
    293 		free(handle);
    294 		return NULL;
    295 	}
    296 
    297 	/*
    298 	 * Current Linux kernels use the protocol family PF_PACKET to
    299 	 * allow direct access to all packets on the network while
    300 	 * older kernels had a special socket type SOCK_PACKET to
    301 	 * implement this feature.
    302 	 * While this old implementation is kind of obsolete we need
    303 	 * to be compatible with older kernels for a while so we are
    304 	 * trying both methods with the newer method preferred.
    305 	 */
    306 
    307 	if ((err = live_open_new(handle, device, promisc, to_ms, ebuf)) == 1)
    308 		live_open_ok = 1;
    309 	else if (err == 0) {
    310 		/* Non-fatal error; try old way */
    311 		if (live_open_old(handle, device, promisc, to_ms, ebuf))
    312 			live_open_ok = 1;
    313 	}
    314 	if (!live_open_ok) {
    315 		/*
    316 		 * Both methods to open the packet socket failed. Tidy
    317 		 * up and report our failure (ebuf is expected to be
    318 		 * set by the functions above).
    319 		 */
    320 
    321 		if (handle->md.device != NULL)
    322 			free(handle->md.device);
    323 		free(handle);
    324 		return NULL;
    325 	}
    326 
    327 	/*
    328 	 * Compute the buffer size.
    329 	 *
    330 	 * If we're using SOCK_PACKET, this might be a 2.0[.x] kernel,
    331 	 * and might require special handling - check.
    332 	 */
    333 	if (handle->md.sock_packet && (uname(&utsname) < 0 ||
    334 	    strncmp(utsname.release, "2.0", 3) == 0)) {
    335 		/*
    336 		 * We're using a SOCK_PACKET structure, and either
    337 		 * we couldn't find out what kernel release this is,
    338 		 * or it's a 2.0[.x] kernel.
    339 		 *
    340 		 * In the 2.0[.x] kernel, a "recvfrom()" on
    341 		 * a SOCK_PACKET socket, with MSG_TRUNC set, will
    342 		 * return the number of bytes read, so if we pass
    343 		 * a length based on the snapshot length, it'll
    344 		 * return the number of bytes from the packet
    345 		 * copied to userland, not the actual length
    346 		 * of the packet.
    347 		 *
    348 		 * This means that, for example, the IP dissector
    349 		 * in tcpdump will get handed a packet length less
    350 		 * than the length in the IP header, and will
    351 		 * complain about "truncated-ip".
    352 		 *
    353 		 * So we don't bother trying to copy from the
    354 		 * kernel only the bytes in which we're interested,
    355 		 * but instead copy them all, just as the older
    356 		 * versions of libpcap for Linux did.
    357 		 *
    358 		 * The buffer therefore needs to be big enough to
    359 		 * hold the largest packet we can get from this
    360 		 * device.  Unfortunately, we can't get the MRU
    361 		 * of the network; we can only get the MTU.  The
    362 		 * MTU may be too small, in which case a packet larger
    363 		 * than the buffer size will be truncated *and* we
    364 		 * won't get the actual packet size.
    365 		 *
    366 		 * However, if the snapshot length is larger than
    367 		 * the buffer size based on the MTU, we use the
    368 		 * snapshot length as the buffer size, instead;
    369 		 * this means that with a sufficiently large snapshot
    370 		 * length we won't artificially truncate packets
    371 		 * to the MTU-based size.
    372 		 *
    373 		 * This mess just one of many problems with packet
    374 		 * capture on 2.0[.x] kernels; you really want a
    375 		 * 2.2[.x] or later kernel if you want packet capture
    376 		 * to work well.
    377 		 */
    378 		mtu = iface_get_mtu(handle->fd, device, ebuf);
    379 		if (mtu == -1) {
    380 			pcap_close_linux(handle);
    381 			free(handle);
    382 			return NULL;
    383 		}
    384 		handle->bufsize = MAX_LINKHEADER_SIZE + mtu;
    385 		if (handle->bufsize < handle->snapshot)
    386 			handle->bufsize = handle->snapshot;
    387 	} else {
    388 		/*
    389 		 * This is a 2.2[.x] or later kernel (we know that
    390 		 * either because we're not using a SOCK_PACKET
    391 		 * socket - PF_PACKET is supported only in 2.2
    392 		 * and later kernels - or because we checked the
    393 		 * kernel version).
    394 		 *
    395 		 * We can safely pass "recvfrom()" a byte count
    396 		 * based on the snapshot length.
    397 		 *
    398 		 * If we're in cooked mode, make the snapshot length
    399 		 * large enough to hold a "cooked mode" header plus
    400 		 * 1 byte of packet data (so we don't pass a byte
    401 		 * count of 0 to "recvfrom()").
    402 		 */
    403 		if (handle->md.cooked) {
    404 			if (handle->snapshot < SLL_HDR_LEN + 1)
    405 				handle->snapshot = SLL_HDR_LEN + 1;
    406 		}
    407 		handle->bufsize = handle->snapshot;
    408 	}
    409 
    410 	/* Allocate the buffer */
    411 
    412 	handle->buffer	 = malloc(handle->bufsize + handle->offset);
    413 	if (!handle->buffer) {
    414 	        snprintf(ebuf, PCAP_ERRBUF_SIZE,
    415 			 "malloc: %s", pcap_strerror(errno));
    416 		pcap_close_linux(handle);
    417 		free(handle);
    418 		return NULL;
    419 	}
    420 
    421 	/*
    422 	 * "handle->fd" is a socket, so "select()" and "poll()"
    423 	 * should work on it.
    424 	 */
    425 	handle->selectable_fd = handle->fd;
    426 
    427 	handle->read_op = pcap_read_linux;
    428 	handle->inject_op = pcap_inject_linux;
    429 	handle->setfilter_op = pcap_setfilter_linux;
    430 	handle->setdirection_op = pcap_setdirection_linux;
    431 	handle->set_datalink_op = NULL;	/* can't change data link type */
    432 	handle->getnonblock_op = pcap_getnonblock_fd;
    433 	handle->setnonblock_op = pcap_setnonblock_fd;
    434 	handle->stats_op = pcap_stats_linux;
    435 	handle->close_op = pcap_close_linux;
    436 
    437 	return handle;
    438 }
    439 
    440 /*
    441  *  Read at most max_packets from the capture stream and call the callback
    442  *  for each of them. Returns the number of packets handled or -1 if an
    443  *  error occured.
    444  */
    445 static int
    446 pcap_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
    447 {
    448 	/*
    449 	 * Currently, on Linux only one packet is delivered per read,
    450 	 * so we don't loop.
    451 	 */
    452 	return pcap_read_packet(handle, callback, user);
    453 }
    454 
    455 /*
    456  *  Read a packet from the socket calling the handler provided by
    457  *  the user. Returns the number of packets received or -1 if an
    458  *  error occured.
    459  */
    460 static int
    461 pcap_read_packet(pcap_t *handle, pcap_handler callback, u_char *userdata)
    462 {
    463 	u_char			*bp;
    464 	int			offset;
    465 #ifdef HAVE_PF_PACKET_SOCKETS
    466 	struct sockaddr_ll	from;
    467 	struct sll_header	*hdrp;
    468 #else
    469 	struct sockaddr		from;
    470 #endif
    471 	socklen_t		fromlen;
    472 	int			packet_len, caplen;
    473 	struct pcap_pkthdr	pcap_header;
    474 
    475 #ifdef HAVE_PF_PACKET_SOCKETS
    476 	/*
    477 	 * If this is a cooked device, leave extra room for a
    478 	 * fake packet header.
    479 	 */
    480 	if (handle->md.cooked)
    481 		offset = SLL_HDR_LEN;
    482 	else
    483 		offset = 0;
    484 #else
    485 	/*
    486 	 * This system doesn't have PF_PACKET sockets, so it doesn't
    487 	 * support cooked devices.
    488 	 */
    489 	offset = 0;
    490 #endif
    491 
    492 	/* Receive a single packet from the kernel */
    493 
    494 	bp = handle->buffer + handle->offset;
    495 	do {
    496 		/*
    497 		 * Has "pcap_breakloop()" been called?
    498 		 */
    499 		if (handle->break_loop) {
    500 			/*
    501 			 * Yes - clear the flag that indicates that it
    502 			 * has, and return -2 as an indication that we
    503 			 * were told to break out of the loop.
    504 			 */
    505 			handle->break_loop = 0;
    506 			return -2;
    507 		}
    508 		fromlen = sizeof(from);
    509 		packet_len = recvfrom(
    510 			handle->fd, bp + offset,
    511 			handle->bufsize - offset, MSG_TRUNC,
    512 			(struct sockaddr *) &from, &fromlen);
    513 	} while (packet_len == -1 && errno == EINTR);
    514 
    515 	/* Check if an error occured */
    516 
    517 	if (packet_len == -1) {
    518 		if (errno == EAGAIN)
    519 			return 0;	/* no packet there */
    520 		else {
    521 			snprintf(handle->errbuf, sizeof(handle->errbuf),
    522 				 "recvfrom: %s", pcap_strerror(errno));
    523 			return -1;
    524 		}
    525 	}
    526 
    527 #ifdef HAVE_PF_PACKET_SOCKETS
    528 	if (!handle->md.sock_packet) {
    529 		/*
    530 		 * Unfortunately, there is a window between socket() and
    531 		 * bind() where the kernel may queue packets from any
    532 		 * interface.  If we're bound to a particular interface,
    533 		 * discard packets not from that interface.
    534 		 *
    535 		 * (If socket filters are supported, we could do the
    536 		 * same thing we do when changing the filter; however,
    537 		 * that won't handle packet sockets without socket
    538 		 * filter support, and it's a bit more complicated.
    539 		 * It would save some instructions per packet, however.)
    540 		 */
    541 		if (handle->md.ifindex != -1 &&
    542 		    from.sll_ifindex != handle->md.ifindex)
    543 			return 0;
    544 
    545 		/*
    546 		 * Do checks based on packet direction.
    547 		 * We can only do this if we're using PF_PACKET; the
    548 		 * address returned for SOCK_PACKET is a "sockaddr_pkt"
    549 		 * which lacks the relevant packet type information.
    550 		 */
    551 		if (from.sll_pkttype == PACKET_OUTGOING) {
    552 			/*
    553 			 * Outgoing packet.
    554 			 * If this is from the loopback device, reject it;
    555 			 * we'll see the packet as an incoming packet as well,
    556 			 * and we don't want to see it twice.
    557 			 */
    558 			if (from.sll_ifindex == handle->md.lo_ifindex)
    559 				return 0;
    560 
    561 			/*
    562 			 * If the user only wants incoming packets, reject it.
    563 			 */
    564 			if (handle->direction == PCAP_D_IN)
    565 				return 0;
    566 		} else {
    567 			/*
    568 			 * Incoming packet.
    569 			 * If the user only wants outgoing packets, reject it.
    570 			 */
    571 			if (handle->direction == PCAP_D_OUT)
    572 				return 0;
    573 		}
    574 	}
    575 #endif
    576 
    577 #ifdef HAVE_PF_PACKET_SOCKETS
    578 	/*
    579 	 * If this is a cooked device, fill in the fake packet header.
    580 	 */
    581 	if (handle->md.cooked) {
    582 		/*
    583 		 * Add the length of the fake header to the length
    584 		 * of packet data we read.
    585 		 */
    586 		packet_len += SLL_HDR_LEN;
    587 
    588 		hdrp = (struct sll_header *)bp;
    589 
    590 		/*
    591 		 * Map the PACKET_ value to a LINUX_SLL_ value; we
    592 		 * want the same numerical value to be used in
    593 		 * the link-layer header even if the numerical values
    594 		 * for the PACKET_ #defines change, so that programs
    595 		 * that look at the packet type field will always be
    596 		 * able to handle DLT_LINUX_SLL captures.
    597 		 */
    598 		switch (from.sll_pkttype) {
    599 
    600 		case PACKET_HOST:
    601 			hdrp->sll_pkttype = htons(LINUX_SLL_HOST);
    602 			break;
    603 
    604 		case PACKET_BROADCAST:
    605 			hdrp->sll_pkttype = htons(LINUX_SLL_BROADCAST);
    606 			break;
    607 
    608 		case PACKET_MULTICAST:
    609 			hdrp->sll_pkttype = htons(LINUX_SLL_MULTICAST);
    610 			break;
    611 
    612 		case PACKET_OTHERHOST:
    613 			hdrp->sll_pkttype = htons(LINUX_SLL_OTHERHOST);
    614 			break;
    615 
    616 		case PACKET_OUTGOING:
    617 			hdrp->sll_pkttype = htons(LINUX_SLL_OUTGOING);
    618 			break;
    619 
    620 		default:
    621 			hdrp->sll_pkttype = -1;
    622 			break;
    623 		}
    624 
    625 		hdrp->sll_hatype = htons(from.sll_hatype);
    626 		hdrp->sll_halen = htons(from.sll_halen);
    627 		memcpy(hdrp->sll_addr, from.sll_addr,
    628 		    (from.sll_halen > SLL_ADDRLEN) ?
    629 		      SLL_ADDRLEN :
    630 		      from.sll_halen);
    631 		hdrp->sll_protocol = from.sll_protocol;
    632 	}
    633 #endif
    634 
    635 	/*
    636 	 * XXX: According to the kernel source we should get the real
    637 	 * packet len if calling recvfrom with MSG_TRUNC set. It does
    638 	 * not seem to work here :(, but it is supported by this code
    639 	 * anyway.
    640 	 * To be honest the code RELIES on that feature so this is really
    641 	 * broken with 2.2.x kernels.
    642 	 * I spend a day to figure out what's going on and I found out
    643 	 * that the following is happening:
    644 	 *
    645 	 * The packet comes from a random interface and the packet_rcv
    646 	 * hook is called with a clone of the packet. That code inserts
    647 	 * the packet into the receive queue of the packet socket.
    648 	 * If a filter is attached to that socket that filter is run
    649 	 * first - and there lies the problem. The default filter always
    650 	 * cuts the packet at the snaplen:
    651 	 *
    652 	 * # tcpdump -d
    653 	 * (000) ret      #68
    654 	 *
    655 	 * So the packet filter cuts down the packet. The recvfrom call
    656 	 * says "hey, it's only 68 bytes, it fits into the buffer" with
    657 	 * the result that we don't get the real packet length. This
    658 	 * is valid at least until kernel 2.2.17pre6.
    659 	 *
    660 	 * We currently handle this by making a copy of the filter
    661 	 * program, fixing all "ret" instructions with non-zero
    662 	 * operands to have an operand of 65535 so that the filter
    663 	 * doesn't truncate the packet, and supplying that modified
    664 	 * filter to the kernel.
    665 	 */
    666 
    667 	caplen = packet_len;
    668 	if (caplen > handle->snapshot)
    669 		caplen = handle->snapshot;
    670 
    671 	/* Run the packet filter if not using kernel filter */
    672 	if (!handle->md.use_bpf && handle->fcode.bf_insns) {
    673 		if (bpf_filter(handle->fcode.bf_insns, bp,
    674 		                packet_len, caplen) == 0)
    675 		{
    676 			/* rejected by filter */
    677 			return 0;
    678 		}
    679 	}
    680 
    681 	/* Fill in our own header data */
    682 
    683 	if (ioctl(handle->fd, SIOCGSTAMP, &pcap_header.ts) == -1) {
    684 		snprintf(handle->errbuf, sizeof(handle->errbuf),
    685 			 "SIOCGSTAMP: %s", pcap_strerror(errno));
    686 		return -1;
    687 	}
    688 	pcap_header.caplen	= caplen;
    689 	pcap_header.len		= packet_len;
    690 
    691 	/*
    692 	 * Count the packet.
    693 	 *
    694 	 * Arguably, we should count them before we check the filter,
    695 	 * as on many other platforms "ps_recv" counts packets
    696 	 * handed to the filter rather than packets that passed
    697 	 * the filter, but if filtering is done in the kernel, we
    698 	 * can't get a count of packets that passed the filter,
    699 	 * and that would mean the meaning of "ps_recv" wouldn't
    700 	 * be the same on all Linux systems.
    701 	 *
    702 	 * XXX - it's not the same on all systems in any case;
    703 	 * ideally, we should have a "get the statistics" call
    704 	 * that supplies more counts and indicates which of them
    705 	 * it supplies, so that we supply a count of packets
    706 	 * handed to the filter only on platforms where that
    707 	 * information is available.
    708 	 *
    709 	 * We count them here even if we can get the packet count
    710 	 * from the kernel, as we can only determine at run time
    711 	 * whether we'll be able to get it from the kernel (if
    712 	 * HAVE_TPACKET_STATS isn't defined, we can't get it from
    713 	 * the kernel, but if it is defined, the library might
    714 	 * have been built with a 2.4 or later kernel, but we
    715 	 * might be running on a 2.2[.x] kernel without Alexey
    716 	 * Kuznetzov's turbopacket patches, and thus the kernel
    717 	 * might not be able to supply those statistics).  We
    718 	 * could, I guess, try, when opening the socket, to get
    719 	 * the statistics, and if we can not increment the count
    720 	 * here, but it's not clear that always incrementing
    721 	 * the count is more expensive than always testing a flag
    722 	 * in memory.
    723 	 *
    724 	 * We keep the count in "md.packets_read", and use that for
    725 	 * "ps_recv" if we can't get the statistics from the kernel.
    726 	 * We do that because, if we *can* get the statistics from
    727 	 * the kernel, we use "md.stat.ps_recv" and "md.stat.ps_drop"
    728 	 * as running counts, as reading the statistics from the
    729 	 * kernel resets the kernel statistics, and if we directly
    730 	 * increment "md.stat.ps_recv" here, that means it will
    731 	 * count packets *twice* on systems where we can get kernel
    732 	 * statistics - once here, and once in pcap_stats_linux().
    733 	 */
    734 	handle->md.packets_read++;
    735 
    736 	/* Call the user supplied callback function */
    737 	callback(userdata, &pcap_header, bp);
    738 
    739 	return 1;
    740 }
    741 
    742 static int
    743 pcap_inject_linux(pcap_t *handle, const void *buf, size_t size)
    744 {
    745 	int ret;
    746 
    747 #ifdef HAVE_PF_PACKET_SOCKETS
    748 	if (!handle->md.sock_packet) {
    749 		/* PF_PACKET socket */
    750 		if (handle->md.ifindex == -1) {
    751 			/*
    752 			 * We don't support sending on the "any" device.
    753 			 */
    754 			strlcpy(handle->errbuf,
    755 			    "Sending packets isn't supported on the \"any\" device",
    756 			    PCAP_ERRBUF_SIZE);
    757 			return (-1);
    758 		}
    759 
    760 		if (handle->md.cooked) {
    761 			/*
    762 			 * We don't support sending on the "any" device.
    763 			 *
    764 			 * XXX - how do you send on a bound cooked-mode
    765 			 * socket?
    766 			 * Is a "sendto()" required there?
    767 			 */
    768 			strlcpy(handle->errbuf,
    769 			    "Sending packets isn't supported in cooked mode",
    770 			    PCAP_ERRBUF_SIZE);
    771 			return (-1);
    772 		}
    773 	}
    774 #endif
    775 
    776 	ret = send(handle->fd, buf, size, 0);
    777 	if (ret == -1) {
    778 		snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
    779 		    pcap_strerror(errno));
    780 		return (-1);
    781 	}
    782 	return (ret);
    783 }
    784 
    785 /*
    786  *  Get the statistics for the given packet capture handle.
    787  *  Reports the number of dropped packets iff the kernel supports
    788  *  the PACKET_STATISTICS "getsockopt()" argument (2.4 and later
    789  *  kernels, and 2.2[.x] kernels with Alexey Kuznetzov's turbopacket
    790  *  patches); otherwise, that information isn't available, and we lie
    791  *  and report 0 as the count of dropped packets.
    792  */
    793 static int
    794 pcap_stats_linux(pcap_t *handle, struct pcap_stat *stats)
    795 {
    796 #ifdef HAVE_TPACKET_STATS
    797 	struct tpacket_stats kstats;
    798 	socklen_t len = sizeof (struct tpacket_stats);
    799 #endif
    800 
    801 #ifdef HAVE_TPACKET_STATS
    802 	/*
    803 	 * Try to get the packet counts from the kernel.
    804 	 */
    805 	if (getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS,
    806 			&kstats, &len) > -1) {
    807 		/*
    808 		 * On systems where the PACKET_STATISTICS "getsockopt()"
    809 		 * argument is supported on PF_PACKET sockets:
    810 		 *
    811 		 *	"ps_recv" counts only packets that *passed* the
    812 		 *	filter, not packets that didn't pass the filter.
    813 		 *	This includes packets later dropped because we
    814 		 *	ran out of buffer space.
    815 		 *
    816 		 *	"ps_drop" counts packets dropped because we ran
    817 		 *	out of buffer space.  It doesn't count packets
    818 		 *	dropped by the interface driver.  It counts only
    819 		 *	packets that passed the filter.
    820 		 *
    821 		 *	Both statistics include packets not yet read from
    822 		 *	the kernel by libpcap, and thus not yet seen by
    823 		 *	the application.
    824 		 *
    825 		 * In "linux/net/packet/af_packet.c", at least in the
    826 		 * 2.4.9 kernel, "tp_packets" is incremented for every
    827 		 * packet that passes the packet filter *and* is
    828 		 * successfully queued on the socket; "tp_drops" is
    829 		 * incremented for every packet dropped because there's
    830 		 * not enough free space in the socket buffer.
    831 		 *
    832 		 * When the statistics are returned for a PACKET_STATISTICS
    833 		 * "getsockopt()" call, "tp_drops" is added to "tp_packets",
    834 		 * so that "tp_packets" counts all packets handed to
    835 		 * the PF_PACKET socket, including packets dropped because
    836 		 * there wasn't room on the socket buffer - but not
    837 		 * including packets that didn't pass the filter.
    838 		 *
    839 		 * In the BSD BPF, the count of received packets is
    840 		 * incremented for every packet handed to BPF, regardless
    841 		 * of whether it passed the filter.
    842 		 *
    843 		 * We can't make "pcap_stats()" work the same on both
    844 		 * platforms, but the best approximation is to return
    845 		 * "tp_packets" as the count of packets and "tp_drops"
    846 		 * as the count of drops.
    847 		 *
    848 		 * Keep a running total because each call to
    849 		 *    getsockopt(handle->fd, SOL_PACKET, PACKET_STATISTICS, ....
    850 		 * resets the counters to zero.
    851 		 */
    852 		handle->md.stat.ps_recv += kstats.tp_packets;
    853 		handle->md.stat.ps_drop += kstats.tp_drops;
    854 		*stats = handle->md.stat;
    855 		return 0;
    856 	}
    857 	else
    858 	{
    859 		/*
    860 		 * If the error was EOPNOTSUPP, fall through, so that
    861 		 * if you build the library on a system with
    862 		 * "struct tpacket_stats" and run it on a system
    863 		 * that doesn't, it works as it does if the library
    864 		 * is built on a system without "struct tpacket_stats".
    865 		 */
    866 		if (errno != EOPNOTSUPP) {
    867 			snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
    868 			    "pcap_stats: %s", pcap_strerror(errno));
    869 			return -1;
    870 		}
    871 	}
    872 #endif
    873 	/*
    874 	 * On systems where the PACKET_STATISTICS "getsockopt()" argument
    875 	 * is not supported on PF_PACKET sockets:
    876 	 *
    877 	 *	"ps_recv" counts only packets that *passed* the filter,
    878 	 *	not packets that didn't pass the filter.  It does not
    879 	 *	count packets dropped because we ran out of buffer
    880 	 *	space.
    881 	 *
    882 	 *	"ps_drop" is not supported.
    883 	 *
    884 	 *	"ps_recv" doesn't include packets not yet read from
    885 	 *	the kernel by libpcap.
    886 	 *
    887 	 * We maintain the count of packets processed by libpcap in
    888 	 * "md.packets_read", for reasons described in the comment
    889 	 * at the end of pcap_read_packet().  We have no idea how many
    890 	 * packets were dropped.
    891 	 */
    892 	stats->ps_recv = handle->md.packets_read;
    893 	stats->ps_drop = 0;
    894 	return 0;
    895 }
    896 
    897 /*
    898  * Description string for the "any" device.
    899  */
    900 static const char any_descr[] = "Pseudo-device that captures on all interfaces";
    901 
    902 int
    903 pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
    904 {
    905 	if (pcap_add_if(alldevsp, "any", 0, any_descr, errbuf) < 0)
    906 		return (-1);
    907 
    908 #ifdef HAVE_DAG_API
    909 	if (dag_platform_finddevs(alldevsp, errbuf) < 0)
    910 		return (-1);
    911 #endif /* HAVE_DAG_API */
    912 
    913 #ifdef HAVE_SEPTEL_API
    914 	if (septel_platform_finddevs(alldevsp, errbuf) < 0)
    915 		return (-1);
    916 #endif /* HAVE_SEPTEL_API */
    917 
    918 	return (0);
    919 }
    920 
    921 /*
    922  *  Attach the given BPF code to the packet capture device.
    923  */
    924 static int
    925 pcap_setfilter_linux(pcap_t *handle, struct bpf_program *filter)
    926 {
    927 #ifdef SO_ATTACH_FILTER
    928 	struct sock_fprog	fcode;
    929 	int			can_filter_in_kernel;
    930 	int			err = 0;
    931 #endif
    932 
    933 	if (!handle)
    934 		return -1;
    935 	if (!filter) {
    936 	        strncpy(handle->errbuf, "setfilter: No filter specified",
    937 			sizeof(handle->errbuf));
    938 		return -1;
    939 	}
    940 
    941 	/* Make our private copy of the filter */
    942 
    943 	if (install_bpf_program(handle, filter) < 0)
    944 		/* install_bpf_program() filled in errbuf */
    945 		return -1;
    946 
    947 	/*
    948 	 * Run user level packet filter by default. Will be overriden if
    949 	 * installing a kernel filter succeeds.
    950 	 */
    951 	handle->md.use_bpf = 0;
    952 
    953 	/* Install kernel level filter if possible */
    954 
    955 #ifdef SO_ATTACH_FILTER
    956 #ifdef USHRT_MAX
    957 	if (handle->fcode.bf_len > USHRT_MAX) {
    958 		/*
    959 		 * fcode.len is an unsigned short for current kernel.
    960 		 * I have yet to see BPF-Code with that much
    961 		 * instructions but still it is possible. So for the
    962 		 * sake of correctness I added this check.
    963 		 */
    964 		fprintf(stderr, "Warning: Filter too complex for kernel\n");
    965 		fcode.len = 0;
    966 		fcode.filter = NULL;
    967 		can_filter_in_kernel = 0;
    968 	} else
    969 #endif /* USHRT_MAX */
    970 	{
    971 		/*
    972 		 * Oh joy, the Linux kernel uses struct sock_fprog instead
    973 		 * of struct bpf_program and of course the length field is
    974 		 * of different size. Pointed out by Sebastian
    975 		 *
    976 		 * Oh, and we also need to fix it up so that all "ret"
    977 		 * instructions with non-zero operands have 65535 as the
    978 		 * operand, and so that, if we're in cooked mode, all
    979 		 * memory-reference instructions use special magic offsets
    980 		 * in references to the link-layer header and assume that
    981 		 * the link-layer payload begins at 0; "fix_program()"
    982 		 * will do that.
    983 		 */
    984 		switch (fix_program(handle, &fcode)) {
    985 
    986 		case -1:
    987 		default:
    988 			/*
    989 			 * Fatal error; just quit.
    990 			 * (The "default" case shouldn't happen; we
    991 			 * return -1 for that reason.)
    992 			 */
    993 			return -1;
    994 
    995 		case 0:
    996 			/*
    997 			 * The program performed checks that we can't make
    998 			 * work in the kernel.
    999 			 */
   1000 			can_filter_in_kernel = 0;
   1001 			break;
   1002 
   1003 		case 1:
   1004 			/*
   1005 			 * We have a filter that'll work in the kernel.
   1006 			 */
   1007 			can_filter_in_kernel = 1;
   1008 			break;
   1009 		}
   1010 	}
   1011 
   1012 	if (can_filter_in_kernel) {
   1013 		if ((err = set_kernel_filter(handle, &fcode)) == 0)
   1014 		{
   1015 			/* Installation succeded - using kernel filter. */
   1016 			handle->md.use_bpf = 1;
   1017 		}
   1018 		else if (err == -1)	/* Non-fatal error */
   1019 		{
   1020 			/*
   1021 			 * Print a warning if we weren't able to install
   1022 			 * the filter for a reason other than "this kernel
   1023 			 * isn't configured to support socket filters.
   1024 			 */
   1025 			if (errno != ENOPROTOOPT && errno != EOPNOTSUPP) {
   1026 				fprintf(stderr,
   1027 				    "Warning: Kernel filter failed: %s\n",
   1028 					pcap_strerror(errno));
   1029 			}
   1030 		}
   1031 	}
   1032 
   1033 	/*
   1034 	 * If we're not using the kernel filter, get rid of any kernel
   1035 	 * filter that might've been there before, e.g. because the
   1036 	 * previous filter could work in the kernel, or because some other
   1037 	 * code attached a filter to the socket by some means other than
   1038 	 * calling "pcap_setfilter()".  Otherwise, the kernel filter may
   1039 	 * filter out packets that would pass the new userland filter.
   1040 	 */
   1041 	if (!handle->md.use_bpf)
   1042 		reset_kernel_filter(handle);
   1043 
   1044 	/*
   1045 	 * Free up the copy of the filter that was made by "fix_program()".
   1046 	 */
   1047 	if (fcode.filter != NULL)
   1048 		free(fcode.filter);
   1049 
   1050 	if (err == -2)
   1051 		/* Fatal error */
   1052 		return -1;
   1053 #endif /* SO_ATTACH_FILTER */
   1054 
   1055 	return 0;
   1056 }
   1057 
   1058 /*
   1059  * Set direction flag: Which packets do we accept on a forwarding
   1060  * single device? IN, OUT or both?
   1061  */
   1062 static int
   1063 pcap_setdirection_linux(pcap_t *handle, pcap_direction_t d)
   1064 {
   1065 #ifdef HAVE_PF_PACKET_SOCKETS
   1066 	if (!handle->md.sock_packet) {
   1067 		handle->direction = d;
   1068 		return 0;
   1069 	}
   1070 #endif
   1071 	/*
   1072 	 * We're not using PF_PACKET sockets, so we can't determine
   1073 	 * the direction of the packet.
   1074 	 */
   1075 	snprintf(handle->errbuf, sizeof(handle->errbuf),
   1076 	    "Setting direction is not supported on SOCK_PACKET sockets");
   1077 	return -1;
   1078 }
   1079 
   1080 /*
   1081  *  Linux uses the ARP hardware type to identify the type of an
   1082  *  interface. pcap uses the DLT_xxx constants for this. This
   1083  *  function takes a pointer to a "pcap_t", and an ARPHRD_xxx
   1084  *  constant, as arguments, and sets "handle->linktype" to the
   1085  *  appropriate DLT_XXX constant and sets "handle->offset" to
   1086  *  the appropriate value (to make "handle->offset" plus link-layer
   1087  *  header length be a multiple of 4, so that the link-layer payload
   1088  *  will be aligned on a 4-byte boundary when capturing packets).
   1089  *  (If the offset isn't set here, it'll be 0; add code as appropriate
   1090  *  for cases where it shouldn't be 0.)
   1091  *
   1092  *  If "cooked_ok" is non-zero, we can use DLT_LINUX_SLL and capture
   1093  *  in cooked mode; otherwise, we can't use cooked mode, so we have
   1094  *  to pick some type that works in raw mode, or fail.
   1095  *
   1096  *  Sets the link type to -1 if unable to map the type.
   1097  */
   1098 static void map_arphrd_to_dlt(pcap_t *handle, int arptype, int cooked_ok)
   1099 {
   1100 	switch (arptype) {
   1101 
   1102 	case ARPHRD_ETHER:
   1103 		/*
   1104 		 * This is (presumably) a real Ethernet capture; give it a
   1105 		 * link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
   1106 		 * that an application can let you choose it, in case you're
   1107 		 * capturing DOCSIS traffic that a Cisco Cable Modem
   1108 		 * Termination System is putting out onto an Ethernet (it
   1109 		 * doesn't put an Ethernet header onto the wire, it puts raw
   1110 		 * DOCSIS frames out on the wire inside the low-level
   1111 		 * Ethernet framing).
   1112 		 *
   1113 		 * XXX - are there any sorts of "fake Ethernet" that have
   1114 		 * ARPHRD_ETHER but that *shouldn't offer DLT_DOCSIS as
   1115 		 * a Cisco CMTS won't put traffic onto it or get traffic
   1116 		 * bridged onto it?  ISDN is handled in "live_open_new()",
   1117 		 * as we fall back on cooked mode there; are there any
   1118 		 * others?
   1119 		 */
   1120 		handle->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
   1121 		/*
   1122 		 * If that fails, just leave the list empty.
   1123 		 */
   1124 		if (handle->dlt_list != NULL) {
   1125 			handle->dlt_list[0] = DLT_EN10MB;
   1126 			handle->dlt_list[1] = DLT_DOCSIS;
   1127 			handle->dlt_count = 2;
   1128 		}
   1129 		/* FALLTHROUGH */
   1130 
   1131 	case ARPHRD_METRICOM:
   1132 	case ARPHRD_LOOPBACK:
   1133 		handle->linktype = DLT_EN10MB;
   1134 		handle->offset = 2;
   1135 		break;
   1136 
   1137 	case ARPHRD_EETHER:
   1138 		handle->linktype = DLT_EN3MB;
   1139 		break;
   1140 
   1141 	case ARPHRD_AX25:
   1142 		handle->linktype = DLT_AX25;
   1143 		break;
   1144 
   1145 	case ARPHRD_PRONET:
   1146 		handle->linktype = DLT_PRONET;
   1147 		break;
   1148 
   1149 	case ARPHRD_CHAOS:
   1150 		handle->linktype = DLT_CHAOS;
   1151 		break;
   1152 
   1153 #ifndef ARPHRD_IEEE802_TR
   1154 #define ARPHRD_IEEE802_TR 800	/* From Linux 2.4 */
   1155 #endif
   1156 	case ARPHRD_IEEE802_TR:
   1157 	case ARPHRD_IEEE802:
   1158 		handle->linktype = DLT_IEEE802;
   1159 		handle->offset = 2;
   1160 		break;
   1161 
   1162 	case ARPHRD_ARCNET:
   1163 		handle->linktype = DLT_ARCNET_LINUX;
   1164 		break;
   1165 
   1166 #ifndef ARPHRD_FDDI	/* From Linux 2.2.13 */
   1167 #define ARPHRD_FDDI	774
   1168 #endif
   1169 	case ARPHRD_FDDI:
   1170 		handle->linktype = DLT_FDDI;
   1171 		handle->offset = 3;
   1172 		break;
   1173 
   1174 #ifndef ARPHRD_ATM  /* FIXME: How to #include this? */
   1175 #define ARPHRD_ATM 19
   1176 #endif
   1177 	case ARPHRD_ATM:
   1178 		/*
   1179 		 * The Classical IP implementation in ATM for Linux
   1180 		 * supports both what RFC 1483 calls "LLC Encapsulation",
   1181 		 * in which each packet has an LLC header, possibly
   1182 		 * with a SNAP header as well, prepended to it, and
   1183 		 * what RFC 1483 calls "VC Based Multiplexing", in which
   1184 		 * different virtual circuits carry different network
   1185 		 * layer protocols, and no header is prepended to packets.
   1186 		 *
   1187 		 * They both have an ARPHRD_ type of ARPHRD_ATM, so
   1188 		 * you can't use the ARPHRD_ type to find out whether
   1189 		 * captured packets will have an LLC header, and,
   1190 		 * while there's a socket ioctl to *set* the encapsulation
   1191 		 * type, there's no ioctl to *get* the encapsulation type.
   1192 		 *
   1193 		 * This means that
   1194 		 *
   1195 		 *	programs that dissect Linux Classical IP frames
   1196 		 *	would have to check for an LLC header and,
   1197 		 *	depending on whether they see one or not, dissect
   1198 		 *	the frame as LLC-encapsulated or as raw IP (I
   1199 		 *	don't know whether there's any traffic other than
   1200 		 *	IP that would show up on the socket, or whether
   1201 		 *	there's any support for IPv6 in the Linux
   1202 		 *	Classical IP code);
   1203 		 *
   1204 		 *	filter expressions would have to compile into
   1205 		 *	code that checks for an LLC header and does
   1206 		 *	the right thing.
   1207 		 *
   1208 		 * Both of those are a nuisance - and, at least on systems
   1209 		 * that support PF_PACKET sockets, we don't have to put
   1210 		 * up with those nuisances; instead, we can just capture
   1211 		 * in cooked mode.  That's what we'll do, if we can.
   1212 		 * Otherwise, we'll just fail.
   1213 		 */
   1214 		if (cooked_ok)
   1215 			handle->linktype = DLT_LINUX_SLL;
   1216 		else
   1217 			handle->linktype = -1;
   1218 		break;
   1219 
   1220 #ifndef ARPHRD_IEEE80211  /* From Linux 2.4.6 */
   1221 #define ARPHRD_IEEE80211 801
   1222 #endif
   1223 	case ARPHRD_IEEE80211:
   1224 		handle->linktype = DLT_IEEE802_11;
   1225 		break;
   1226 
   1227 #ifndef ARPHRD_IEEE80211_PRISM  /* From Linux 2.4.18 */
   1228 #define ARPHRD_IEEE80211_PRISM 802
   1229 #endif
   1230 	case ARPHRD_IEEE80211_PRISM:
   1231 		handle->linktype = DLT_PRISM_HEADER;
   1232 		break;
   1233 
   1234 #ifndef ARPHRD_IEEE80211_RADIOTAP /* new */
   1235 #define ARPHRD_IEEE80211_RADIOTAP 803
   1236 #endif
   1237 	case ARPHRD_IEEE80211_RADIOTAP:
   1238 		handle->linktype = DLT_IEEE802_11_RADIO;
   1239 		break;
   1240 
   1241 	case ARPHRD_PPP:
   1242 		/*
   1243 		 * Some PPP code in the kernel supplies no link-layer
   1244 		 * header whatsoever to PF_PACKET sockets; other PPP
   1245 		 * code supplies PPP link-layer headers ("syncppp.c");
   1246 		 * some PPP code might supply random link-layer
   1247 		 * headers (PPP over ISDN - there's code in Ethereal,
   1248 		 * for example, to cope with PPP-over-ISDN captures
   1249 		 * with which the Ethereal developers have had to cope,
   1250 		 * heuristically trying to determine which of the
   1251 		 * oddball link-layer headers particular packets have).
   1252 		 *
   1253 		 * As such, we just punt, and run all PPP interfaces
   1254 		 * in cooked mode, if we can; otherwise, we just treat
   1255 		 * it as DLT_RAW, for now - if somebody needs to capture,
   1256 		 * on a 2.0[.x] kernel, on PPP devices that supply a
   1257 		 * link-layer header, they'll have to add code here to
   1258 		 * map to the appropriate DLT_ type (possibly adding a
   1259 		 * new DLT_ type, if necessary).
   1260 		 */
   1261 		if (cooked_ok)
   1262 			handle->linktype = DLT_LINUX_SLL;
   1263 		else {
   1264 			/*
   1265 			 * XXX - handle ISDN types here?  We can't fall
   1266 			 * back on cooked sockets, so we'd have to
   1267 			 * figure out from the device name what type of
   1268 			 * link-layer encapsulation it's using, and map
   1269 			 * that to an appropriate DLT_ value, meaning
   1270 			 * we'd map "isdnN" devices to DLT_RAW (they
   1271 			 * supply raw IP packets with no link-layer
   1272 			 * header) and "isdY" devices to a new DLT_I4L_IP
   1273 			 * type that has only an Ethernet packet type as
   1274 			 * a link-layer header.
   1275 			 *
   1276 			 * But sometimes we seem to get random crap
   1277 			 * in the link-layer header when capturing on
   1278 			 * ISDN devices....
   1279 			 */
   1280 			handle->linktype = DLT_RAW;
   1281 		}
   1282 		break;
   1283 
   1284 #ifndef ARPHRD_CISCO
   1285 #define ARPHRD_CISCO 513 /* previously ARPHRD_HDLC */
   1286 #endif
   1287 	case ARPHRD_CISCO:
   1288 		handle->linktype = DLT_C_HDLC;
   1289 		break;
   1290 
   1291 	/* Not sure if this is correct for all tunnels, but it
   1292 	 * works for CIPE */
   1293 	case ARPHRD_TUNNEL:
   1294 #ifndef ARPHRD_SIT
   1295 #define ARPHRD_SIT 776	/* From Linux 2.2.13 */
   1296 #endif
   1297 	case ARPHRD_SIT:
   1298 	case ARPHRD_CSLIP:
   1299 	case ARPHRD_SLIP6:
   1300 	case ARPHRD_CSLIP6:
   1301 	case ARPHRD_ADAPT:
   1302 	case ARPHRD_SLIP:
   1303 #ifndef ARPHRD_RAWHDLC
   1304 #define ARPHRD_RAWHDLC 518
   1305 #endif
   1306 	case ARPHRD_RAWHDLC:
   1307 #ifndef ARPHRD_DLCI
   1308 #define ARPHRD_DLCI 15
   1309 #endif
   1310 	case ARPHRD_DLCI:
   1311 		/*
   1312 		 * XXX - should some of those be mapped to DLT_LINUX_SLL
   1313 		 * instead?  Should we just map all of them to DLT_LINUX_SLL?
   1314 		 */
   1315 		handle->linktype = DLT_RAW;
   1316 		break;
   1317 
   1318 #ifndef ARPHRD_FRAD
   1319 #define ARPHRD_FRAD 770
   1320 #endif
   1321 	case ARPHRD_FRAD:
   1322 		handle->linktype = DLT_FRELAY;
   1323 		break;
   1324 
   1325 	case ARPHRD_LOCALTLK:
   1326 		handle->linktype = DLT_LTALK;
   1327 		break;
   1328 
   1329 #ifndef ARPHRD_FCPP
   1330 #define ARPHRD_FCPP	784
   1331 #endif
   1332 	case ARPHRD_FCPP:
   1333 #ifndef ARPHRD_FCAL
   1334 #define ARPHRD_FCAL	785
   1335 #endif
   1336 	case ARPHRD_FCAL:
   1337 #ifndef ARPHRD_FCPL
   1338 #define ARPHRD_FCPL	786
   1339 #endif
   1340 	case ARPHRD_FCPL:
   1341 #ifndef ARPHRD_FCFABRIC
   1342 #define ARPHRD_FCFABRIC	787
   1343 #endif
   1344 	case ARPHRD_FCFABRIC:
   1345 		/*
   1346 		 * We assume that those all mean RFC 2625 IP-over-
   1347 		 * Fibre Channel, with the RFC 2625 header at
   1348 		 * the beginning of the packet.
   1349 		 */
   1350 		handle->linktype = DLT_IP_OVER_FC;
   1351 		break;
   1352 
   1353 #ifndef ARPHRD_IRDA
   1354 #define ARPHRD_IRDA	783
   1355 #endif
   1356 	case ARPHRD_IRDA:
   1357 		/* Don't expect IP packet out of this interfaces... */
   1358 		handle->linktype = DLT_LINUX_IRDA;
   1359 		/* We need to save packet direction for IrDA decoding,
   1360 		 * so let's use "Linux-cooked" mode. Jean II */
   1361 		//handle->md.cooked = 1;
   1362 		break;
   1363 
   1364 	/* ARPHRD_LAPD is unofficial and randomly allocated, if reallocation
   1365 	 * is needed, please report it to <daniele (at) orlandi.com> */
   1366 #ifndef ARPHRD_LAPD
   1367 #define ARPHRD_LAPD	8445
   1368 #endif
   1369 	case ARPHRD_LAPD:
   1370 		/* Don't expect IP packet out of this interfaces... */
   1371 		handle->linktype = DLT_LINUX_LAPD;
   1372 		break;
   1373 
   1374 	default:
   1375 		handle->linktype = -1;
   1376 		break;
   1377 	}
   1378 }
   1379 
   1380 /* ===== Functions to interface to the newer kernels ================== */
   1381 
   1382 /*
   1383  *  Try to open a packet socket using the new kernel interface.
   1384  *  Returns 0 on failure.
   1385  *  FIXME: 0 uses to mean success (Sebastian)
   1386  */
   1387 static int
   1388 live_open_new(pcap_t *handle, const char *device, int promisc,
   1389 	      int to_ms, char *ebuf)
   1390 {
   1391 #ifdef HAVE_PF_PACKET_SOCKETS
   1392 	int			sock_fd = -1, arptype;
   1393 	int			err;
   1394 	int			fatal_err = 0;
   1395 	struct packet_mreq	mr;
   1396 
   1397 	/* One shot loop used for error handling - bail out with break */
   1398 
   1399 	do {
   1400 		/*
   1401 		 * Open a socket with protocol family packet. If a device is
   1402 		 * given we try to open it in raw mode otherwise we use
   1403 		 * the cooked interface.
   1404 		 */
   1405 		sock_fd = device ?
   1406 			socket(PF_PACKET, SOCK_RAW, htons(ETH_P_ALL))
   1407 		      : socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL));
   1408 
   1409 		if (sock_fd == -1) {
   1410 			snprintf(ebuf, PCAP_ERRBUF_SIZE, "socket: %s",
   1411 				 pcap_strerror(errno) );
   1412 			break;
   1413 		}
   1414 
   1415 		/* It seems the kernel supports the new interface. */
   1416 		handle->md.sock_packet = 0;
   1417 
   1418 		/*
   1419 		 * Get the interface index of the loopback device.
   1420 		 * If the attempt fails, don't fail, just set the
   1421 		 * "md.lo_ifindex" to -1.
   1422 		 *
   1423 		 * XXX - can there be more than one device that loops
   1424 		 * packets back, i.e. devices other than "lo"?  If so,
   1425 		 * we'd need to find them all, and have an array of
   1426 		 * indices for them, and check all of them in
   1427 		 * "pcap_read_packet()".
   1428 		 */
   1429 		handle->md.lo_ifindex = iface_get_id(sock_fd, "lo", ebuf);
   1430 
   1431 		/*
   1432 		 * Default value for offset to align link-layer payload
   1433 		 * on a 4-byte boundary.
   1434 		 */
   1435 		handle->offset	 = 0;
   1436 
   1437 		/*
   1438 		 * What kind of frames do we have to deal with? Fall back
   1439 		 * to cooked mode if we have an unknown interface type.
   1440 		 */
   1441 
   1442 		if (device) {
   1443 			/* Assume for now we don't need cooked mode. */
   1444 			handle->md.cooked = 0;
   1445 
   1446 			arptype	= iface_get_arptype(sock_fd, device, ebuf);
   1447 			if (arptype == -1) {
   1448 				fatal_err = 1;
   1449 				break;
   1450 			}
   1451 			map_arphrd_to_dlt(handle, arptype, 1);
   1452 			if (handle->linktype == -1 ||
   1453 			    handle->linktype == DLT_LINUX_SLL ||
   1454 			    handle->linktype == DLT_LINUX_IRDA ||
   1455 			    handle->linktype == DLT_LINUX_LAPD ||
   1456 			    (handle->linktype == DLT_EN10MB &&
   1457 			     (strncmp("isdn", device, 4) == 0 ||
   1458 			      strncmp("isdY", device, 4) == 0))) {
   1459 				/*
   1460 				 * Unknown interface type (-1), or a
   1461 				 * device we explicitly chose to run
   1462 				 * in cooked mode (e.g., PPP devices),
   1463 				 * or an ISDN device (whose link-layer
   1464 				 * type we can only determine by using
   1465 				 * APIs that may be different on different
   1466 				 * kernels) - reopen in cooked mode.
   1467 				 */
   1468 				if (close(sock_fd) == -1) {
   1469 					snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1470 						 "close: %s", pcap_strerror(errno));
   1471 					break;
   1472 				}
   1473 				sock_fd = socket(PF_PACKET, SOCK_DGRAM,
   1474 						 htons(ETH_P_ALL));
   1475 				if (sock_fd == -1) {
   1476 					snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1477 						 "socket: %s", pcap_strerror(errno));
   1478 					break;
   1479 				}
   1480 				handle->md.cooked = 1;
   1481 
   1482 				/*
   1483 				 * Get rid of any link-layer type list
   1484 				 * we allocated - this only supports cooked
   1485 				 * capture.
   1486 				 */
   1487 				if (handle->dlt_list != NULL) {
   1488 					free(handle->dlt_list);
   1489 					handle->dlt_list = NULL;
   1490 					handle->dlt_count = 0;
   1491 				}
   1492 
   1493 				if (handle->linktype == -1) {
   1494 					/*
   1495 					 * Warn that we're falling back on
   1496 					 * cooked mode; we may want to
   1497 					 * update "map_arphrd_to_dlt()"
   1498 					 * to handle the new type.
   1499 					 */
   1500 					snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1501 						"arptype %d not "
   1502 						"supported by libpcap - "
   1503 						"falling back to cooked "
   1504 						"socket",
   1505 						arptype);
   1506 				}
   1507 				/* IrDA capture is not a real "cooked" capture,
   1508 				 * it's IrLAP frames, not IP packets. */
   1509 				if (handle->linktype != DLT_LINUX_IRDA &&
   1510 			    		handle->linktype != DLT_LINUX_LAPD)
   1511 					handle->linktype = DLT_LINUX_SLL;
   1512 			}
   1513 
   1514 			handle->md.ifindex = iface_get_id(sock_fd, device, ebuf);
   1515 			if (handle->md.ifindex == -1)
   1516 				break;
   1517 
   1518 			if ((err = iface_bind(sock_fd, handle->md.ifindex,
   1519 			    ebuf)) < 0) {
   1520 				if (err == -2)
   1521 					fatal_err = 1;
   1522 				break;
   1523 			}
   1524 		} else {
   1525 			/*
   1526 			 * This is cooked mode.
   1527 			 */
   1528 			handle->md.cooked = 1;
   1529 			handle->linktype = DLT_LINUX_SLL;
   1530 
   1531 			/*
   1532 			 * We're not bound to a device.
   1533 			 * XXX - true?  Or true only if we're using
   1534 			 * the "any" device?
   1535 			 * For now, we're using this as an indication
   1536 			 * that we can't transmit; stop doing that only
   1537 			 * if we figure out how to transmit in cooked
   1538 			 * mode.
   1539 			 */
   1540 			handle->md.ifindex = -1;
   1541 		}
   1542 
   1543 		/*
   1544 		 * Select promiscuous mode on if "promisc" is set.
   1545 		 *
   1546 		 * Do not turn allmulti mode on if we don't select
   1547 		 * promiscuous mode - on some devices (e.g., Orinoco
   1548 		 * wireless interfaces), allmulti mode isn't supported
   1549 		 * and the driver implements it by turning promiscuous
   1550 		 * mode on, and that screws up the operation of the
   1551 		 * card as a normal networking interface, and on no
   1552 		 * other platform I know of does starting a non-
   1553 		 * promiscuous capture affect which multicast packets
   1554 		 * are received by the interface.
   1555 		 */
   1556 
   1557 		/*
   1558 		 * Hmm, how can we set promiscuous mode on all interfaces?
   1559 		 * I am not sure if that is possible at all.
   1560 		 */
   1561 
   1562 		if (device && promisc) {
   1563 			memset(&mr, 0, sizeof(mr));
   1564 			mr.mr_ifindex = handle->md.ifindex;
   1565 			mr.mr_type    = PACKET_MR_PROMISC;
   1566 			if (setsockopt(sock_fd, SOL_PACKET,
   1567 				PACKET_ADD_MEMBERSHIP, &mr, sizeof(mr)) == -1)
   1568 			{
   1569 				snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1570 					"setsockopt: %s", pcap_strerror(errno));
   1571 				break;
   1572 			}
   1573 		}
   1574 
   1575 		/* Save the socket FD in the pcap structure */
   1576 
   1577 		handle->fd 	 = sock_fd;
   1578 
   1579 		return 1;
   1580 
   1581 	} while(0);
   1582 
   1583 	if (sock_fd != -1)
   1584 		close(sock_fd);
   1585 
   1586 	if (fatal_err) {
   1587 		/*
   1588 		 * Get rid of any link-layer type list we allocated.
   1589 		 */
   1590 		if (handle->dlt_list != NULL)
   1591 			free(handle->dlt_list);
   1592 		return -2;
   1593 	} else
   1594 		return 0;
   1595 #else
   1596 	strncpy(ebuf,
   1597 		"New packet capturing interface not supported by build "
   1598 		"environment", PCAP_ERRBUF_SIZE);
   1599 	return 0;
   1600 #endif
   1601 }
   1602 
   1603 #ifdef HAVE_PF_PACKET_SOCKETS
   1604 /*
   1605  *  Return the index of the given device name. Fill ebuf and return
   1606  *  -1 on failure.
   1607  */
   1608 static int
   1609 iface_get_id(int fd, const char *device, char *ebuf)
   1610 {
   1611 	struct ifreq	ifr;
   1612 
   1613 	memset(&ifr, 0, sizeof(ifr));
   1614 	strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
   1615 
   1616 	if (ioctl(fd, SIOCGIFINDEX, &ifr) == -1) {
   1617 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1618 			 "SIOCGIFINDEX: %s", pcap_strerror(errno));
   1619 		return -1;
   1620 	}
   1621 
   1622 	return ifr.ifr_ifindex;
   1623 }
   1624 
   1625 /*
   1626  *  Bind the socket associated with FD to the given device.
   1627  */
   1628 static int
   1629 iface_bind(int fd, int ifindex, char *ebuf)
   1630 {
   1631 	struct sockaddr_ll	sll;
   1632 	int			err;
   1633 	socklen_t		errlen = sizeof(err);
   1634 
   1635 	memset(&sll, 0, sizeof(sll));
   1636 	sll.sll_family		= AF_PACKET;
   1637 	sll.sll_ifindex		= ifindex;
   1638 	sll.sll_protocol	= htons(ETH_P_ALL);
   1639 
   1640 	if (bind(fd, (struct sockaddr *) &sll, sizeof(sll)) == -1) {
   1641 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1642 			 "bind: %s", pcap_strerror(errno));
   1643 		return -1;
   1644 	}
   1645 
   1646 	/* Any pending errors, e.g., network is down? */
   1647 
   1648 	if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
   1649 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1650 			"getsockopt: %s", pcap_strerror(errno));
   1651 		return -2;
   1652 	}
   1653 
   1654 	if (err > 0) {
   1655 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1656 			"bind: %s", pcap_strerror(err));
   1657 		return -2;
   1658 	}
   1659 
   1660 	return 0;
   1661 }
   1662 
   1663 #endif
   1664 
   1665 
   1666 /* ===== Functions to interface to the older kernels ================== */
   1667 
   1668 /*
   1669  * With older kernels promiscuous mode is kind of interesting because we
   1670  * have to reset the interface before exiting. The problem can't really
   1671  * be solved without some daemon taking care of managing usage counts.
   1672  * If we put the interface into promiscuous mode, we set a flag indicating
   1673  * that we must take it out of that mode when the interface is closed,
   1674  * and, when closing the interface, if that flag is set we take it out
   1675  * of promiscuous mode.
   1676  */
   1677 
   1678 /*
   1679  * List of pcaps for which we turned promiscuous mode on by hand.
   1680  * If there are any such pcaps, we arrange to call "pcap_close_all()"
   1681  * when we exit, and have it close all of them to turn promiscuous mode
   1682  * off.
   1683  */
   1684 static struct pcap *pcaps_to_close;
   1685 
   1686 /*
   1687  * TRUE if we've already called "atexit()" to cause "pcap_close_all()" to
   1688  * be called on exit.
   1689  */
   1690 static int did_atexit;
   1691 
   1692 static void	pcap_close_all(void)
   1693 {
   1694 	struct pcap *handle;
   1695 
   1696 	while ((handle = pcaps_to_close) != NULL)
   1697 		pcap_close(handle);
   1698 }
   1699 
   1700 static void	pcap_close_linux( pcap_t *handle )
   1701 {
   1702 	struct pcap	*p, *prevp;
   1703 	struct ifreq	ifr;
   1704 
   1705 	if (handle->md.clear_promisc) {
   1706 		/*
   1707 		 * We put the interface into promiscuous mode; take
   1708 		 * it out of promiscuous mode.
   1709 		 *
   1710 		 * XXX - if somebody else wants it in promiscuous mode,
   1711 		 * this code cannot know that, so it'll take it out
   1712 		 * of promiscuous mode.  That's not fixable in 2.0[.x]
   1713 		 * kernels.
   1714 		 */
   1715 		memset(&ifr, 0, sizeof(ifr));
   1716 		strncpy(ifr.ifr_name, handle->md.device, sizeof(ifr.ifr_name));
   1717 		if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
   1718 			fprintf(stderr,
   1719 			    "Can't restore interface flags (SIOCGIFFLAGS failed: %s).\n"
   1720 			    "Please adjust manually.\n"
   1721 			    "Hint: This can't happen with Linux >= 2.2.0.\n",
   1722 			    strerror(errno));
   1723 		} else {
   1724 			if (ifr.ifr_flags & IFF_PROMISC) {
   1725 				/*
   1726 				 * Promiscuous mode is currently on; turn it
   1727 				 * off.
   1728 				 */
   1729 				ifr.ifr_flags &= ~IFF_PROMISC;
   1730 				if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
   1731 					fprintf(stderr,
   1732 					    "Can't restore interface flags (SIOCSIFFLAGS failed: %s).\n"
   1733 					    "Please adjust manually.\n"
   1734 					    "Hint: This can't happen with Linux >= 2.2.0.\n",
   1735 					    strerror(errno));
   1736 				}
   1737 			}
   1738 		}
   1739 
   1740 		/*
   1741 		 * Take this pcap out of the list of pcaps for which we
   1742 		 * have to take the interface out of promiscuous mode.
   1743 		 */
   1744 		for (p = pcaps_to_close, prevp = NULL; p != NULL;
   1745 		    prevp = p, p = p->md.next) {
   1746 			if (p == handle) {
   1747 				/*
   1748 				 * Found it.  Remove it from the list.
   1749 				 */
   1750 				if (prevp == NULL) {
   1751 					/*
   1752 					 * It was at the head of the list.
   1753 					 */
   1754 					pcaps_to_close = p->md.next;
   1755 				} else {
   1756 					/*
   1757 					 * It was in the middle of the list.
   1758 					 */
   1759 					prevp->md.next = p->md.next;
   1760 				}
   1761 				break;
   1762 			}
   1763 		}
   1764 	}
   1765 
   1766 	if (handle->md.device != NULL)
   1767 		free(handle->md.device);
   1768 	handle->md.device = NULL;
   1769 	pcap_close_common(handle);
   1770 }
   1771 
   1772 /*
   1773  *  Try to open a packet socket using the old kernel interface.
   1774  *  Returns 0 on failure.
   1775  *  FIXME: 0 uses to mean success (Sebastian)
   1776  */
   1777 static int
   1778 live_open_old(pcap_t *handle, const char *device, int promisc,
   1779 	      int to_ms, char *ebuf)
   1780 {
   1781 	int		arptype;
   1782 	struct ifreq	ifr;
   1783 
   1784 	do {
   1785 		/* Open the socket */
   1786 
   1787 		handle->fd = socket(PF_INET, SOCK_PACKET, htons(ETH_P_ALL));
   1788 		if (handle->fd == -1) {
   1789 			snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1790 				 "socket: %s", pcap_strerror(errno));
   1791 			break;
   1792 		}
   1793 
   1794 		/* It worked - we are using the old interface */
   1795 		handle->md.sock_packet = 1;
   1796 
   1797 		/* ...which means we get the link-layer header. */
   1798 		handle->md.cooked = 0;
   1799 
   1800 		/* Bind to the given device */
   1801 
   1802 		if (!device) {
   1803 		        strncpy(ebuf, "pcap_open_live: The \"any\" device isn't supported on 2.0[.x]-kernel systems",
   1804 				PCAP_ERRBUF_SIZE);
   1805 			break;
   1806 		}
   1807 		if (iface_bind_old(handle->fd, device, ebuf) == -1)
   1808 			break;
   1809 
   1810 		/*
   1811 		 * Try to get the link-layer type.
   1812 		 */
   1813 		arptype = iface_get_arptype(handle->fd, device, ebuf);
   1814 		if (arptype == -1)
   1815 			break;
   1816 
   1817 		/*
   1818 		 * Try to find the DLT_ type corresponding to that
   1819 		 * link-layer type.
   1820 		 */
   1821 		map_arphrd_to_dlt(handle, arptype, 0);
   1822 		if (handle->linktype == -1) {
   1823 			snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1824 				 "unknown arptype %d", arptype);
   1825 			break;
   1826 		}
   1827 
   1828 		/* Go to promisc mode if requested */
   1829 
   1830 		if (promisc) {
   1831 			memset(&ifr, 0, sizeof(ifr));
   1832 			strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
   1833 			if (ioctl(handle->fd, SIOCGIFFLAGS, &ifr) == -1) {
   1834 				snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1835 					 "SIOCGIFFLAGS: %s", pcap_strerror(errno));
   1836 				break;
   1837 			}
   1838 			if ((ifr.ifr_flags & IFF_PROMISC) == 0) {
   1839 				/*
   1840 				 * Promiscuous mode isn't currently on,
   1841 				 * so turn it on, and remember that
   1842 				 * we should turn it off when the
   1843 				 * pcap_t is closed.
   1844 				 */
   1845 
   1846 				/*
   1847 				 * If we haven't already done so, arrange
   1848 				 * to have "pcap_close_all()" called when
   1849 				 * we exit.
   1850 				 */
   1851 				if (!did_atexit) {
   1852 					if (atexit(pcap_close_all) == -1) {
   1853 						/*
   1854 						 * "atexit()" failed; don't
   1855 						 * put the interface in
   1856 						 * promiscuous mode, just
   1857 						 * give up.
   1858 						 */
   1859 						strncpy(ebuf, "atexit failed",
   1860 							PCAP_ERRBUF_SIZE);
   1861 						break;
   1862 					}
   1863 					did_atexit = 1;
   1864 				}
   1865 
   1866 				ifr.ifr_flags |= IFF_PROMISC;
   1867 				if (ioctl(handle->fd, SIOCSIFFLAGS, &ifr) == -1) {
   1868 				        snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1869 						 "SIOCSIFFLAGS: %s",
   1870 						 pcap_strerror(errno));
   1871 					break;
   1872 				}
   1873 				handle->md.clear_promisc = 1;
   1874 
   1875 				/*
   1876 				 * Add this to the list of pcaps
   1877 				 * to close when we exit.
   1878 				 */
   1879 				handle->md.next = pcaps_to_close;
   1880 				pcaps_to_close = handle;
   1881 			}
   1882 		}
   1883 
   1884 		/*
   1885 		 * Default value for offset to align link-layer payload
   1886 		 * on a 4-byte boundary.
   1887 		 */
   1888 		handle->offset	 = 0;
   1889 
   1890 		return 1;
   1891 
   1892 	} while (0);
   1893 
   1894 	pcap_close_linux(handle);
   1895 	return 0;
   1896 }
   1897 
   1898 /*
   1899  *  Bind the socket associated with FD to the given device using the
   1900  *  interface of the old kernels.
   1901  */
   1902 static int
   1903 iface_bind_old(int fd, const char *device, char *ebuf)
   1904 {
   1905 	struct sockaddr	saddr;
   1906 	int		err;
   1907 	socklen_t	errlen = sizeof(err);
   1908 
   1909 	memset(&saddr, 0, sizeof(saddr));
   1910 	strncpy(saddr.sa_data, device, sizeof(saddr.sa_data));
   1911 	if (bind(fd, &saddr, sizeof(saddr)) == -1) {
   1912 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1913 			 "bind: %s", pcap_strerror(errno));
   1914 		return -1;
   1915 	}
   1916 
   1917 	/* Any pending errors, e.g., network is down? */
   1918 
   1919 	if (getsockopt(fd, SOL_SOCKET, SO_ERROR, &err, &errlen) == -1) {
   1920 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1921 			"getsockopt: %s", pcap_strerror(errno));
   1922 		return -1;
   1923 	}
   1924 
   1925 	if (err > 0) {
   1926 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1927 			"bind: %s", pcap_strerror(err));
   1928 		return -1;
   1929 	}
   1930 
   1931 	return 0;
   1932 }
   1933 
   1934 
   1935 /* ===== System calls available on all supported kernels ============== */
   1936 
   1937 /*
   1938  *  Query the kernel for the MTU of the given interface.
   1939  */
   1940 static int
   1941 iface_get_mtu(int fd, const char *device, char *ebuf)
   1942 {
   1943 	struct ifreq	ifr;
   1944 
   1945 	if (!device)
   1946 		return BIGGER_THAN_ALL_MTUS;
   1947 
   1948 	memset(&ifr, 0, sizeof(ifr));
   1949 	strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
   1950 
   1951 	if (ioctl(fd, SIOCGIFMTU, &ifr) == -1) {
   1952 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1953 			 "SIOCGIFMTU: %s", pcap_strerror(errno));
   1954 		return -1;
   1955 	}
   1956 
   1957 	return ifr.ifr_mtu;
   1958 }
   1959 
   1960 /*
   1961  *  Get the hardware type of the given interface as ARPHRD_xxx constant.
   1962  */
   1963 static int
   1964 iface_get_arptype(int fd, const char *device, char *ebuf)
   1965 {
   1966 	struct ifreq	ifr;
   1967 
   1968 	memset(&ifr, 0, sizeof(ifr));
   1969 	strncpy(ifr.ifr_name, device, sizeof(ifr.ifr_name));
   1970 
   1971 	if (ioctl(fd, SIOCGIFHWADDR, &ifr) == -1) {
   1972 		snprintf(ebuf, PCAP_ERRBUF_SIZE,
   1973 			 "SIOCGIFHWADDR: %s", pcap_strerror(errno));
   1974 		return -1;
   1975 	}
   1976 
   1977 	return ifr.ifr_hwaddr.sa_family;
   1978 }
   1979 
   1980 #ifdef SO_ATTACH_FILTER
   1981 static int
   1982 fix_program(pcap_t *handle, struct sock_fprog *fcode)
   1983 {
   1984 	size_t prog_size;
   1985 	register int i;
   1986 	register struct bpf_insn *p;
   1987 	struct bpf_insn *f;
   1988 	int len;
   1989 
   1990 	/*
   1991 	 * Make a copy of the filter, and modify that copy if
   1992 	 * necessary.
   1993 	 */
   1994 	prog_size = sizeof(*handle->fcode.bf_insns) * handle->fcode.bf_len;
   1995 	len = handle->fcode.bf_len;
   1996 	f = (struct bpf_insn *)malloc(prog_size);
   1997 	if (f == NULL) {
   1998 		snprintf(handle->errbuf, sizeof(handle->errbuf),
   1999 			 "malloc: %s", pcap_strerror(errno));
   2000 		return -1;
   2001 	}
   2002 	memcpy(f, handle->fcode.bf_insns, prog_size);
   2003 	fcode->len = len;
   2004 	fcode->filter = (struct sock_filter *) f;
   2005 
   2006 	for (i = 0; i < len; ++i) {
   2007 		p = &f[i];
   2008 		/*
   2009 		 * What type of instruction is this?
   2010 		 */
   2011 		switch (BPF_CLASS(p->code)) {
   2012 
   2013 		case BPF_RET:
   2014 			/*
   2015 			 * It's a return instruction; is the snapshot
   2016 			 * length a constant, rather than the contents
   2017 			 * of the accumulator?
   2018 			 */
   2019 			if (BPF_MODE(p->code) == BPF_K) {
   2020 				/*
   2021 				 * Yes - if the value to be returned,
   2022 				 * i.e. the snapshot length, is anything
   2023 				 * other than 0, make it 65535, so that
   2024 				 * the packet is truncated by "recvfrom()",
   2025 				 * not by the filter.
   2026 				 *
   2027 				 * XXX - there's nothing we can easily do
   2028 				 * if it's getting the value from the
   2029 				 * accumulator; we'd have to insert
   2030 				 * code to force non-zero values to be
   2031 				 * 65535.
   2032 				 */
   2033 				if (p->k != 0)
   2034 					p->k = 65535;
   2035 			}
   2036 			break;
   2037 
   2038 		case BPF_LD:
   2039 		case BPF_LDX:
   2040 			/*
   2041 			 * It's a load instruction; is it loading
   2042 			 * from the packet?
   2043 			 */
   2044 			switch (BPF_MODE(p->code)) {
   2045 
   2046 			case BPF_ABS:
   2047 			case BPF_IND:
   2048 			case BPF_MSH:
   2049 				/*
   2050 				 * Yes; are we in cooked mode?
   2051 				 */
   2052 				if (handle->md.cooked) {
   2053 					/*
   2054 					 * Yes, so we need to fix this
   2055 					 * instruction.
   2056 					 */
   2057 					if (fix_offset(p) < 0) {
   2058 						/*
   2059 						 * We failed to do so.
   2060 						 * Return 0, so our caller
   2061 						 * knows to punt to userland.
   2062 						 */
   2063 						return 0;
   2064 					}
   2065 				}
   2066 				break;
   2067 			}
   2068 			break;
   2069 		}
   2070 	}
   2071 	return 1;	/* we succeeded */
   2072 }
   2073 
   2074 static int
   2075 fix_offset(struct bpf_insn *p)
   2076 {
   2077 	/*
   2078 	 * What's the offset?
   2079 	 */
   2080 	if (p->k >= SLL_HDR_LEN) {
   2081 		/*
   2082 		 * It's within the link-layer payload; that starts at an
   2083 		 * offset of 0, as far as the kernel packet filter is
   2084 		 * concerned, so subtract the length of the link-layer
   2085 		 * header.
   2086 		 */
   2087 		p->k -= SLL_HDR_LEN;
   2088 	} else if (p->k == 14) {
   2089 		/*
   2090 		 * It's the protocol field; map it to the special magic
   2091 		 * kernel offset for that field.
   2092 		 */
   2093 		p->k = SKF_AD_OFF + SKF_AD_PROTOCOL;
   2094 	} else {
   2095 		/*
   2096 		 * It's within the header, but it's not one of those
   2097 		 * fields; we can't do that in the kernel, so punt
   2098 		 * to userland.
   2099 		 */
   2100 		return -1;
   2101 	}
   2102 	return 0;
   2103 }
   2104 
   2105 static int
   2106 set_kernel_filter(pcap_t *handle, struct sock_fprog *fcode)
   2107 {
   2108 	int total_filter_on = 0;
   2109 	int save_mode;
   2110 	int ret;
   2111 	int save_errno;
   2112 
   2113 	/*
   2114 	 * The socket filter code doesn't discard all packets queued
   2115 	 * up on the socket when the filter is changed; this means
   2116 	 * that packets that don't match the new filter may show up
   2117 	 * after the new filter is put onto the socket, if those
   2118 	 * packets haven't yet been read.
   2119 	 *
   2120 	 * This means, for example, that if you do a tcpdump capture
   2121 	 * with a filter, the first few packets in the capture might
   2122 	 * be packets that wouldn't have passed the filter.
   2123 	 *
   2124 	 * We therefore discard all packets queued up on the socket
   2125 	 * when setting a kernel filter.  (This isn't an issue for
   2126 	 * userland filters, as the userland filtering is done after
   2127 	 * packets are queued up.)
   2128 	 *
   2129 	 * To flush those packets, we put the socket in read-only mode,
   2130 	 * and read packets from the socket until there are no more to
   2131 	 * read.
   2132 	 *
   2133 	 * In order to keep that from being an infinite loop - i.e.,
   2134 	 * to keep more packets from arriving while we're draining
   2135 	 * the queue - we put the "total filter", which is a filter
   2136 	 * that rejects all packets, onto the socket before draining
   2137 	 * the queue.
   2138 	 *
   2139 	 * This code deliberately ignores any errors, so that you may
   2140 	 * get bogus packets if an error occurs, rather than having
   2141 	 * the filtering done in userland even if it could have been
   2142 	 * done in the kernel.
   2143 	 */
   2144 	if (setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
   2145 		       &total_fcode, sizeof(total_fcode)) == 0) {
   2146 		char drain[1];
   2147 
   2148 		/*
   2149 		 * Note that we've put the total filter onto the socket.
   2150 		 */
   2151 		total_filter_on = 1;
   2152 
   2153 		/*
   2154 		 * Save the socket's current mode, and put it in
   2155 		 * non-blocking mode; we drain it by reading packets
   2156 		 * until we get an error (which is normally a
   2157 		 * "nothing more to be read" error).
   2158 		 */
   2159 		save_mode = fcntl(handle->fd, F_GETFL, 0);
   2160 		if (save_mode != -1 &&
   2161 		    fcntl(handle->fd, F_SETFL, save_mode | O_NONBLOCK) >= 0) {
   2162 			while (recv(handle->fd, &drain, sizeof drain,
   2163 			       MSG_TRUNC) >= 0)
   2164 				;
   2165 			save_errno = errno;
   2166 			fcntl(handle->fd, F_SETFL, save_mode);
   2167 			if (save_errno != EAGAIN) {
   2168 				/* Fatal error */
   2169 				reset_kernel_filter(handle);
   2170 				snprintf(handle->errbuf, sizeof(handle->errbuf),
   2171 				 "recv: %s", pcap_strerror(save_errno));
   2172 				return -2;
   2173 			}
   2174 		}
   2175 	}
   2176 
   2177 	/*
   2178 	 * Now attach the new filter.
   2179 	 */
   2180 	ret = setsockopt(handle->fd, SOL_SOCKET, SO_ATTACH_FILTER,
   2181 			 fcode, sizeof(*fcode));
   2182 	if (ret == -1 && total_filter_on) {
   2183 		/*
   2184 		 * Well, we couldn't set that filter on the socket,
   2185 		 * but we could set the total filter on the socket.
   2186 		 *
   2187 		 * This could, for example, mean that the filter was
   2188 		 * too big to put into the kernel, so we'll have to
   2189 		 * filter in userland; in any case, we'll be doing
   2190 		 * filtering in userland, so we need to remove the
   2191 		 * total filter so we see packets.
   2192 		 */
   2193 		save_errno = errno;
   2194 
   2195 		/*
   2196 		 * XXX - if this fails, we're really screwed;
   2197 		 * we have the total filter on the socket,
   2198 		 * and it won't come off.  What do we do then?
   2199 		 */
   2200 		reset_kernel_filter(handle);
   2201 
   2202 		errno = save_errno;
   2203 	}
   2204 	return ret;
   2205 }
   2206 
   2207 static int
   2208 reset_kernel_filter(pcap_t *handle)
   2209 {
   2210 	/*
   2211 	 * setsockopt() barfs unless it get a dummy parameter.
   2212 	 * valgrind whines unless the value is initialized,
   2213 	 * as it has no idea that setsockopt() ignores its
   2214 	 * parameter.
   2215 	 */
   2216 	int dummy = 0;
   2217 
   2218 	return setsockopt(handle->fd, SOL_SOCKET, SO_DETACH_FILTER,
   2219 				   &dummy, sizeof(dummy));
   2220 }
   2221 #endif
   2222