/*
* dhcpcd - DHCP client daemon
*
* 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.
*
* THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
*/
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/socket.h>
#include <sys/uio.h>
#include <net/bpf.h>
#include <net/if.h>
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <paths.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include "config.h"
#include "common.h"
#include "dhcp.h"
#include "logger.h"
#include "net.h"
#include "bpf-filter.h"
int
open_socket(struct interface *iface, int protocol)
{
int fd = -1;
int *fdp = NULL;
struct ifreq ifr;
int buf_len = 0;
struct bpf_version pv;
struct bpf_program pf;
#ifdef BIOCIMMEDIATE
int flags;
#endif
#ifdef _PATH_BPF
fd = open(_PATH_BPF, O_RDWR | O_NONBLOCK);
#else
char *device;
int n = 0;
device = xmalloc(sizeof(char) * PATH_MAX);
do {
snprintf(device, PATH_MAX, "/dev/bpf%d", n++);
fd = open(device, O_RDWR | O_NONBLOCK);
} while (fd == -1 && errno == EBUSY);
free(device);
#endif
if (fd == -1)
return -1;
if (ioctl(fd, BIOCVERSION, &pv) == -1)
goto eexit;
if (pv.bv_major != BPF_MAJOR_VERSION ||
pv.bv_minor < BPF_MINOR_VERSION) {
logger(LOG_ERR, "BPF version mismatch - recompile " PACKAGE);
goto eexit;
}
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, iface->name, sizeof(ifr.ifr_name));
if (ioctl(fd, BIOCSETIF, &ifr) == -1)
goto eexit;
/* Get the required BPF buffer length from the kernel. */
if (ioctl(fd, BIOCGBLEN, &buf_len) == -1)
goto eexit;
if (iface->buffer_size != (size_t)buf_len) {
free(iface->buffer);
iface->buffer_size = buf_len;
iface->buffer = xmalloc(buf_len);
iface->buffer_len = iface->buffer_pos = 0;
}
#ifdef BIOCIMMEDIATE
flags = 1;
if (ioctl(fd, BIOCIMMEDIATE, &flags) == -1)
goto eexit;
#endif
/* Install the DHCP filter */
if (protocol == ETHERTYPE_ARP) {
pf.bf_insns = UNCONST(arp_bpf_filter);
pf.bf_len = arp_bpf_filter_len;
fdp = &iface->arp_fd;
} else {
pf.bf_insns = UNCONST(dhcp_bpf_filter);
pf.bf_len = dhcp_bpf_filter_len;
fdp = &iface->raw_fd;
}
if (ioctl(fd, BIOCSETF, &pf) == -1)
goto eexit;
if (set_cloexec(fd) == -1)
goto eexit;
if (fdp) {
if (*fdp != -1)
close(*fdp);
*fdp = fd;
}
return fd;
eexit:
free(iface->buffer);
iface->buffer = NULL;
close(fd);
return -1;
}
ssize_t
send_raw_packet(const struct interface *iface, int protocol,
const void *data, ssize_t len)
{
struct iovec iov[2];
struct ether_header hw;
int fd;
memset(&hw, 0, ETHER_HDR_LEN);
memset(&hw.ether_dhost, 0xff, ETHER_ADDR_LEN);
hw.ether_type = htons(protocol);
iov[0].iov_base = &hw;
iov[0].iov_len = ETHER_HDR_LEN;
iov[1].iov_base = UNCONST(data);
iov[1].iov_len = len;
if (protocol == ETHERTYPE_ARP)
fd = iface->arp_fd;
else
fd = iface->raw_fd;
return writev(fd, iov, 2);
}
/* BPF requires that we read the entire buffer.
* So we pass the buffer in the API so we can loop on >1 packet. */
ssize_t
get_raw_packet(struct interface *iface, int protocol,
void *data, ssize_t len)
{
int fd = -1;
struct bpf_hdr packet;
ssize_t bytes;
const unsigned char *payload;
if (protocol == ETHERTYPE_ARP)
fd = iface->arp_fd;
else
fd = iface->raw_fd;
for (;;) {
if (iface->buffer_len == 0) {
bytes = read(fd, iface->buffer, iface->buffer_size);
if (bytes == -1)
return errno == EAGAIN ? 0 : -1;
else if ((size_t)bytes < sizeof(packet))
return -1;
iface->buffer_len = bytes;
iface->buffer_pos = 0;
}
bytes = -1;
memcpy(&packet, iface->buffer + iface->buffer_pos,
sizeof(packet));
if (packet.bh_caplen != packet.bh_datalen)
goto next; /* Incomplete packet, drop. */
if (iface->buffer_pos + packet.bh_caplen + packet.bh_hdrlen >
iface->buffer_len)
goto next; /* Packet beyond buffer, drop. */
payload = iface->buffer + packet.bh_hdrlen + ETHER_HDR_LEN;
bytes = packet.bh_caplen - ETHER_HDR_LEN;
if (bytes > len)
bytes = len;
memcpy(data, payload, bytes);
next:
iface->buffer_pos += BPF_WORDALIGN(packet.bh_hdrlen +
packet.bh_caplen);
if (iface->buffer_pos >= iface->buffer_len)
iface->buffer_len = iface->buffer_pos = 0;
if (bytes != -1)
return bytes;
}
}
