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/*
* Copyright (c) 2009 Felix Obenhuber
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. The name of the author may not be used to endorse or promote
* products derived from this software without specific prior written
* permission.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*
* SocketCan sniffing API implementation for Linux platform
* By Felix Obenhuber <felix@obenhuber.de>
*
*/

#ifdef HAVE_CONFIG_H
#include "config.h"
#endif

#include "pcap-int.h"
#include "pcap-can-linux.h"

#ifdef NEED_STRERROR_H
#include "strerror.h"
#endif

#include <errno.h>
#include <stdlib.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <net/if.h>
#include <arpa/inet.h>

#include <linux/can.h>
#include <linux/can/raw.h>

/* not yet defined anywhere */
#ifndef PF_CAN
#define PF_CAN 29
#endif
#ifndef AF_CAN
#define AF_CAN PF_CAN
#endif

/* forward declaration */
static int can_activate(pcap_t *);
static int can_read_linux(pcap_t *, int , pcap_handler , u_char *);
static int can_inject_linux(pcap_t *, const void *, size_t);
static int can_setfilter_linux(pcap_t *, struct bpf_program *);
static int can_setdirection_linux(pcap_t *, pcap_direction_t);
static int can_stats_linux(pcap_t *, struct pcap_stat *);

pcap_t *
can_create(const char *device, char *ebuf)
{
pcap_t* p;

p = pcap_create_common(device, ebuf);
if (p == NULL)
return (NULL);

p->activate_op = can_activate;
return (p);
}


static int
can_activate(pcap_t* handle)
{
struct sockaddr_can addr;
struct ifreq ifr;

/* Initialize some components of the pcap structure. */
handle->bufsize = 24;
handle->offset = 8;
handle->linktype = DLT_CAN_SOCKETCAN;
handle->read_op = can_read_linux;
handle->inject_op = can_inject_linux;
handle->setfilter_op = can_setfilter_linux;
handle->setdirection_op = can_setdirection_linux;
handle->set_datalink_op = NULL;
handle->getnonblock_op = pcap_getnonblock_fd;
handle->setnonblock_op = pcap_setnonblock_fd;
handle->stats_op = can_stats_linux;

/* Create socket */
handle->fd = socket(PF_CAN, SOCK_RAW, CAN_RAW);
if (handle->fd < 0)
{
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't create raw socket %d:%s",
errno, strerror(errno));
return PCAP_ERROR;
}

/* get interface index */
memset(&ifr, 0, sizeof(ifr));
strncpy(ifr.ifr_name, handle->opt.source, sizeof(ifr.ifr_name));
if (ioctl(handle->fd, SIOCGIFINDEX, &ifr) < 0)
{
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE,
"Unable to get interface index: %s",
pcap_strerror(errno));
pcap_cleanup_live_common(handle);
return PCAP_ERROR;
}
handle->md.ifindex = ifr.ifr_ifindex;

/* allocate butter */
handle->buffer = malloc(handle->bufsize);
if (!handle->buffer)
{
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't allocate dump buffer: %s",
pcap_strerror(errno));
pcap_cleanup_live_common(handle);
return PCAP_ERROR;
}

/* Bind to the socket */
addr.can_family = AF_CAN;
addr.can_ifindex = handle->md.ifindex;
if( bind( handle->fd, (struct sockaddr*)&addr, sizeof(addr) ) < 0 )
{
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't attach to device %d %d:%s",
handle->md.ifindex, errno, strerror(errno));
pcap_cleanup_live_common(handle);
return PCAP_ERROR;
}

if (handle->opt.rfmon)
{
/* Monitor mode doesn't apply to CAN devices. */
pcap_cleanup_live_common(handle);
return PCAP_ERROR;
}

handle->selectable_fd = handle->fd;
return 0;

}


static int
can_read_linux(pcap_t *handle, int max_packets, pcap_handler callback, u_char *user)
{
struct msghdr msg;
struct pcap_pkthdr pkth;
struct iovec iv;
struct can_frame* cf;

iv.iov_base = &handle->buffer[handle->offset];
iv.iov_len = handle->snapshot;

memset(&msg, 0, sizeof(msg));
msg.msg_iov = &iv;
msg.msg_iovlen = 1;
msg.msg_control = handle->buffer;
msg.msg_controllen = handle->offset;

do
{
pkth.caplen = recvmsg(handle->fd, &msg, 0);
if (handle->break_loop)
{
handle->break_loop = 0;
return -2;
}
} while ((pkth.caplen == -1) && (errno == EINTR));

if (pkth.caplen < 0)
{
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't receive packet %d:%s",
errno, strerror(errno));
return -1;
}

/* adjust capture len according to frame len */
cf = (struct can_frame*)&handle->buffer[8];
pkth.caplen -= 8 - cf->can_dlc;
pkth.len = pkth.caplen;

cf->can_id = htonl( cf->can_id );

if( -1 == gettimeofday(&pkth.ts, NULL) )
{
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "Can't get time of day %d:%s",
errno, strerror(errno));
return -1;
}

callback(user, &pkth, &handle->buffer[8]);

return 1;
}


static int
can_inject_linux(pcap_t *handle, const void *buf, size_t size)
{
/* not yet implemented */
snprintf(handle->errbuf, PCAP_ERRBUF_SIZE, "inject not supported on "
"can devices");
return (-1);
}


static int
can_stats_linux(pcap_t *handle, struct pcap_stat *stats)
{
/* not yet implemented */
stats->ps_recv = 0; /* number of packets received */
stats->ps_drop = 0; /* number of packets dropped */
stats->ps_ifdrop = 0; /* drops by interface -- only supported on some platforms */
return 0;
}


static int
can_setfilter_linux(pcap_t *p, struct bpf_program *fp)
{
/* not yet implemented */
return 0;
}


static int
can_setdirection_linux(pcap_t *p, pcap_direction_t d)
{
/* no support for PCAP_D_OUT */
if (d == PCAP_D_OUT)
{
snprintf(p->errbuf, sizeof(p->errbuf),
"Setting direction to PCAP_D_OUT is not supported on can");
return -1;
}

p->direction = d;

return 0;
}


/* eof */
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