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      1 /*
      2  * Copyright (c) 2009 Felix Obenhuber
      3  * All rights reserved.
      4  *
      5  * Redistribution and use in source and binary forms, with or without
      6  * modification, are permitted provided that the following conditions
      7  * are met:
      8  *
      9  * 1. Redistributions of source code must retain the above copyright
     10  * notice, this list of conditions and the following disclaimer.
     11  * 2. Redistributions in binary form must reproduce the above copyright
     12  * notice, this list of conditions and the following disclaimer in the
     13  * documentation and/or other materials provided with the distribution.
     14  * 3. The name of the author may not be used to endorse or promote
     15  * products derived from this software without specific prior written
     16  * permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  *
     30  * SocketCan sniffing API implementation for Linux platform
     31  * By Felix Obenhuber <felix (at) obenhuber.de>
     32  *
     33  */
     34 
     35 #ifdef HAVE_CONFIG_H
     36 #include "config.h"
     37 #endif
     38 
     39 #include "pcap-int.h"
     40 #include "pcap-can-linux.h"
     41 
     42 #ifdef NEED_STRERROR_H
     43 #include "strerror.h"
     44 #endif
     45 
     46 #include <errno.h>
     47 #include <stdlib.h>
     48 #include <unistd.h>
     49 #include <fcntl.h>
     50 #include <string.h>
     51 #include <sys/ioctl.h>
     52 #include <sys/socket.h>
     53 #include <net/if.h>
     54 #include <arpa/inet.h>
     55 
     56 #include <linux/can.h>
     57 #include <linux/can/raw.h>
     58 
     59 /* not yet defined anywhere */
     60 #ifndef PF_CAN
     61 #define PF_CAN 29
     62 #endif
     63 #ifndef AF_CAN
     64 #define AF_CAN PF_CAN
     65 #endif
     66 
     67 /* forward declaration */
     68 static int can_activate(pcap_t *);
     69 static int can_read_linux(pcap_t *, int , pcap_handler , u_char *);
     70 static int can_inject_linux(pcap_t *, const void *, size_t);
     71 static int can_setfilter_linux(pcap_t *, struct bpf_program *);
     72 static int can_setdirection_linux(pcap_t *, pcap_direction_t);
     73 static int can_stats_linux(pcap_t *, struct pcap_stat *);
     74 
     75 /*
     76  * Private data for capturing on Linux CANbus devices.
     77  */
     78 struct pcap_can {
     79 	int ifindex;		/* interface index of device we're bound to */
     80 };
     81 
     82 int
     83 can_findalldevs(pcap_if_t **devlistp, char *errbuf)
     84 {
     85 	/*
     86 	 * There are no platform-specific devices since each device
     87 	 * exists as a regular network interface.
     88 	 *
     89 	 * XXX - true?
     90 	 */
     91 	return 0;
     92 }
     93 
     94 pcap_t *
     95 can_create(const char *device, char *ebuf, int *is_ours)
     96 {
     97 	const char *cp;
     98 	char *cpend;
     99 	long devnum;
    100 	pcap_t* p;
    101 
    102 	/* Does this look like a CANbus device? */
    103 	cp = strrchr(device, '/');
    104 	if (cp == NULL)
    105 		cp = device;
    106 	/* Does it begin with "can" or "vcan"? */
    107 	if (strncmp(cp, "can", 3) == 0) {
    108 		/* Begins with "can" */
    109 		cp += 3;	/* skip past "can" */
    110 	} else if (strncmp(cp, "vcan", 4) == 0) {
    111 		/* Begins with "vcan" */
    112 		cp += 4;
    113 	} else {
    114 		/* Nope, doesn't begin with "can" or "vcan" */
    115 		*is_ours = 0;
    116 		return NULL;
    117 	}
    118 	/* Yes - is "can" or "vcan" followed by a number from 0? */
    119 	devnum = strtol(cp, &cpend, 10);
    120 	if (cpend == cp || *cpend != '\0') {
    121 		/* Not followed by a number. */
    122 		*is_ours = 0;
    123 		return NULL;
    124 	}
    125 	if (devnum < 0) {
    126 		/* Followed by a non-valid number. */
    127 		*is_ours = 0;
    128 		return NULL;
    129 	}
    130 
    131 	/* OK, it's probably ours. */
    132 	*is_ours = 1;
    133 
    134 	p = pcap_create_common(device, ebuf, sizeof (struct pcap_can));
    135 	if (p == NULL)
    136 		return (NULL);
    137 
    138 	p->activate_op = can_activate;
    139 	return (p);
    140 }
    141 
    142 
    143 static int
    144 can_activate(pcap_t* handle)
    145 {
    146 	struct pcap_can *handlep = handle->priv;
    147 	struct sockaddr_can addr;
    148 	struct ifreq ifr;
    149 
    150 	/* Initialize some components of the pcap structure. */
    151 	handle->bufsize = 24;
    152 	handle->offset = 8;
    153 	handle->linktype = DLT_CAN_SOCKETCAN;
    154 	handle->read_op = can_read_linux;
    155 	handle->inject_op = can_inject_linux;
    156 	handle->setfilter_op = can_setfilter_linux;
    157 	handle->setdirection_op = can_setdirection_linux;
    158 	handle->set_datalink_op = NULL;
    159 	handle->getnonblock_op = pcap_getnonblock_fd;
    160 	handle->setnonblock_op = pcap_setnonblock_fd;
    161 	handle->stats_op = can_stats_linux;
    162 
    163 	/* Create socket */
    164 	handle->fd = socket(PF_CAN, SOCK_RAW, CAN_RAW);
    165 	if (handle->fd < 0)
    166 	{
    167 		snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't create raw socket %d:%s",
    168 			errno, strerror(errno));
    169 		return PCAP_ERROR;
    170 	}
    171 
    172 	/* get interface index */
    173 	memset(&ifr, 0, sizeof(ifr));
    174 	strncpy(ifr.ifr_name, handle->opt.source, sizeof(ifr.ifr_name));
    175 	if (ioctl(handle->fd, SIOCGIFINDEX, &ifr) < 0)
    176 	{
    177 		snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
    178 				"Unable to get interface index: %s",
    179 			pcap_strerror(errno));
    180 		pcap_cleanup_live_common(handle);
    181 		return PCAP_ERROR;
    182 	}
    183 	handlep->ifindex = ifr.ifr_ifindex;
    184 
    185 	/* allocate butter */
    186 	handle->buffer = malloc(handle->bufsize);
    187 	if (!handle->buffer)
    188 	{
    189 		snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate dump buffer: %s",
    190 			pcap_strerror(errno));
    191 		pcap_cleanup_live_common(handle);
    192 		return PCAP_ERROR;
    193 	}
    194 
    195 	/* Bind to the socket */
    196 	addr.can_family = AF_CAN;
    197 	addr.can_ifindex = handlep->ifindex;
    198 	if( bind( handle->fd, (struct sockaddr*)&addr, sizeof(addr) ) < 0  )
    199 	{
    200 		snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't attach to device %d %d:%s",
    201 			handlep->ifindex, errno, strerror(errno));
    202 		pcap_cleanup_live_common(handle);
    203 		return PCAP_ERROR;
    204 	}
    205 
    206 	if (handle->opt.rfmon)
    207 	{
    208 		/* Monitor mode doesn't apply to CAN devices. */
    209 		pcap_cleanup_live_common(handle);
    210 		return PCAP_ERROR_RFMON_NOTSUP;
    211 	}
    212 
    213 	handle->selectable_fd = handle->fd;
    214 	return 0;
    215 
    216 }
    217 
    218 
    219 static int
    220 can_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
    221 {
    222 	struct msghdr msg;
    223 	struct pcap_pkthdr pkth;
    224 	struct iovec iv;
    225 	struct can_frame* cf;
    226 
    227 	iv.iov_base = &handle->buffer[handle->offset];
    228 	iv.iov_len = handle->snapshot;
    229 
    230 	memset(&msg, 0, sizeof(msg));
    231 	msg.msg_iov = &iv;
    232 	msg.msg_iovlen = 1;
    233 	msg.msg_control = handle->buffer;
    234 	msg.msg_controllen = handle->offset;
    235 
    236 	do
    237 	{
    238 		pkth.caplen = recvmsg(handle->fd, &msg, 0);
    239 		if (handle->break_loop)
    240 		{
    241 			handle->break_loop = 0;
    242 			return -2;
    243 		}
    244 	} while ((pkth.caplen == -1) && (errno == EINTR));
    245 
    246 	if (pkth.caplen < 0)
    247 	{
    248 		snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't receive packet %d:%s",
    249 			errno, strerror(errno));
    250 		return -1;
    251 	}
    252 
    253 	/* adjust capture len according to frame len */
    254 	cf = (struct can_frame*)&handle->buffer[8];
    255 	pkth.caplen -= 8 - cf->can_dlc;
    256 	pkth.len = pkth.caplen;
    257 
    258 	cf->can_id = htonl( cf->can_id );
    259 
    260 	if( -1 == gettimeofday(&pkth.ts, NULL) )
    261 	{
    262 		snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't get time of day %d:%s",
    263 			errno, strerror(errno));
    264 		return -1;
    265 	}
    266 
    267 	callback(user, &pkth, &handle->buffer[8]);
    268 
    269 	return 1;
    270 }
    271 
    272 
    273 static int
    274 can_inject_linux(pcap_t *handle, const void *buf, size_t size)
    275 {
    276 	/* not yet implemented */
    277 	snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on "
    278 		"can devices");
    279 	return (-1);
    280 }
    281 
    282 
    283 static int
    284 can_stats_linux(pcap_t *handle, struct pcap_stat *stats)
    285 {
    286 	/* not yet implemented */
    287 	stats->ps_recv = 0;			 /* number of packets received */
    288 	stats->ps_drop = 0;			 /* number of packets dropped */
    289 	stats->ps_ifdrop = 0;		 /* drops by interface -- only supported on some platforms */
    290 	return 0;
    291 }
    292 
    293 
    294 static int
    295 can_setfilter_linux(pcap_t *p, struct bpf_program *fp)
    296 {
    297 	/* not yet implemented */
    298 	return 0;
    299 }
    300 
    301 
    302 static int
    303 can_setdirection_linux(pcap_t *p, pcap_direction_t d)
    304 {
    305 	/* no support for PCAP_D_OUT */
    306 	if (d == PCAP_D_OUT)
    307 	{
    308 		snprintf(p->errbuf, sizeof(p->errbuf),
    309 			"Setting direction to PCAP_D_OUT is not supported on can");
    310 		return -1;
    311 	}
    312 
    313 	p->direction = d;
    314 
    315 	return 0;
    316 }
    317 
    318 
    319 /* eof */
    320