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@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 */
68static int can_activate(pcap_t *);
69static int can_read_linux(pcap_t *, int , pcap_handler , u_char *);
70static int can_inject_linux(pcap_t *, const void *, size_t);
71static int can_setfilter_linux(pcap_t *, struct bpf_program *);
72static int can_setdirection_linux(pcap_t *, pcap_direction_t);
73static int can_stats_linux(pcap_t *, struct pcap_stat *);
74
75/*
76 * Private data for capturing on Linux CANbus devices.
77 */
78struct pcap_can {
79	int ifindex;		/* interface index of device we're bound to */
80};
81
82int
83can_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
94pcap_t *
95can_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
143static int
144can_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
219static int
220can_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
273static int
274can_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
283static int
284can_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
294static int
295can_setfilter_linux(pcap_t *p, struct bpf_program *fp)
296{
297	/* not yet implemented */
298	return 0;
299}
300
301
302static int
303can_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