/*
* Copyright (c) 2014 embedded brains GmbH. All rights reserved.
*
* embedded brains GmbH
* Dornierstr. 4
* 82178 Puchheim
* Germany
* <rtems@embedded-brains.de>
*
* Copyright (c) 2006-2013 Roy Marples <roy@marples.name>
*
* Some parts are derived from the dhcpcd sources.
*
* http://roy.marples.name/projects/dhcpcd
*
* 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 <rtems/bsd/util.h>
#include <sys/cdefs.h>
#include <sys/ioctl.h>
#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <net/bpf.h>
#include <net/if_dl.h>
#include <arpa/inet.h>
#include <errno.h>
#include <fcntl.h>
#include <ifaddrs.h>
#include <stdlib.h>
#include <string.h>
struct rtems_bsd_arp_processor_context {
int fd;
uint8_t eaddr[ETHER_ADDR_LEN];
size_t buf_size;
uint8_t buf[];
};
#ifndef BPF_ETHCOOK
# define BPF_ETHCOOK 0
#endif
#ifndef BPF_WHOLEPACKET
# define BPF_WHOLEPACKET ~0U
#endif
static const struct bpf_insn arp_bpf_filter[] = {
/* Make sure this is an ARP packet... */
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 12),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_ARP, 0, 3),
/* Make sure this is an ARP REQUEST... */
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 2, 0),
/* or ARP REPLY... */
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, 20 + BPF_ETHCOOK),
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 0, 1),
/* If we passed all the tests, ask for the whole packet. */
BPF_STMT(BPF_RET + BPF_K, BPF_WHOLEPACKET),
/* Otherwise, drop it. */
BPF_STMT(BPF_RET + BPF_K, 0)
};
static const size_t arp_bpf_filter_len =
sizeof(arp_bpf_filter) / sizeof(arp_bpf_filter[0]);
static void
process_arp_packet(const uint8_t *pkt, size_t pkt_size, int fd,
const uint8_t eaddr[ETHER_ADDR_LEN], rtems_bsd_arp_processor processor,
void *arg)
{
struct arphdr ar;
uint32_t spa;
uint32_t tpa;
const uint8_t *sha;
const uint8_t *tha;
/* We must have a full ARP header */
if (pkt_size < sizeof(ar))
return;
memcpy(&ar, pkt, sizeof(ar));
/* Protocol must be IP. */
if (ar.ar_pro != htons(ETHERTYPE_IP))
return;
if (ar.ar_pln != sizeof(spa))
return;
/* Only these types are recognised */
if (ar.ar_op != htons(ARPOP_REPLY) &&
ar.ar_op != htons(ARPOP_REQUEST))
return;
/* Get pointers to the hardware addresses */
sha = pkt + sizeof(ar);
tha = sha + ar.ar_hln + ar.ar_pln;
/* Ensure we got all the data */
if ((tha + ar.ar_hln + ar.ar_pln) - pkt > pkt_size)
return;
/* Ignore messages from ourself */
if (ar.ar_hln == ETHER_ADDR_LEN &&
memcmp(sha, &eaddr[0], ETHER_ADDR_LEN) == 0)
return;
/* Copy out the IP addresses */
memcpy(&spa, sha + ar.ar_hln, ar.ar_pln);
memcpy(&tpa, tha + ar.ar_hln, ar.ar_pln);
(*processor)(arg, fd, eaddr, &ar, spa, tpa, sha, tha);
}
rtems_bsd_arp_processor_context *
rtems_bsd_arp_processor_create(const char *ifname)
{
rtems_bsd_arp_processor_context *ctx = NULL;
int fd = -1;
struct ifreq ifr;
int buf_len;
size_t buf_size;
struct bpf_version pv;
struct bpf_program pf;
int flags;
int rv;
fd = open("/dev/bpf", O_RDWR);
if (fd < 0) {
goto error;
}
rv = ioctl(fd, BIOCVERSION, &pv);
if (rv != 0 || pv.bv_major != BPF_MAJOR_VERSION ||
pv.bv_minor < BPF_MINOR_VERSION) {
goto error;
}
memset(&ifr, 0, sizeof(ifr));
strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name));
rv = ioctl(fd, BIOCSETIF, &ifr);
if (rv != 0) {
goto error;
}
rv = ioctl(fd, BIOCGBLEN, &buf_len);
if (rv != 0 || buf_len <= 0) {
goto error;
}
buf_size = (size_t) buf_len;
flags = 1;
rv = ioctl(fd, BIOCIMMEDIATE, &flags);
if (rv != 0) {
goto error;
}
pf.bf_insns = __DECONST(struct bpf_insn *, arp_bpf_filter);
pf.bf_len = arp_bpf_filter_len;
rv = ioctl(fd, BIOCSETF, &pf);
if (rv != 0) {
goto error;
}
ctx = malloc(sizeof(*ctx) + buf_size);
if (ctx == NULL) {
goto error;
}
rv = rtems_bsd_get_ethernet_addr(ifname, &ctx->eaddr[0]);
if (rv != 0) {
goto error;
}
ctx->fd = fd;
ctx->buf_size = buf_size;
return ctx;
error:
close(fd);
free(ctx);
return NULL;
}
int
rtems_bsd_arp_processor_get_file_descriptor(
const rtems_bsd_arp_processor_context *ctx)
{
return ctx->fd;
}
int
rtems_bsd_arp_processor_process(
rtems_bsd_arp_processor_context *ctx,
rtems_bsd_arp_processor processor, void *arg)
{
ssize_t n;
size_t buf_avail;
size_t buf_pos;
n = read(ctx->fd, &ctx->buf[0], ctx->buf_size);
if (n < 0) {
return -1;
}
buf_avail = (size_t) n;
buf_pos = 0;
while (buf_pos < buf_avail) {
const uint8_t *pkt = &ctx->buf[0] + buf_pos;
struct bpf_hdr bp;
memcpy(&bp, pkt, sizeof(bp));
if (bp.bh_caplen == bp.bh_datalen &&
buf_pos + bp.bh_caplen + bp.bh_hdrlen <= buf_avail) {
const uint8_t *payload = pkt + bp.bh_hdrlen +
ETHER_HDR_LEN;
size_t payload_size = bp.bh_caplen - ETHER_HDR_LEN;
process_arp_packet(payload, payload_size, ctx->fd, ctx->eaddr,
processor, NULL);
}
buf_pos += BPF_WORDALIGN(bp.bh_hdrlen + bp.bh_caplen);
}
return 0;
}
