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/***
This file is part of systemd.
Copyright (C) 2014 Axis Communications AB. All rights reserved.
systemd is free software; you can redistribute it and/or modify it
under the terms of the GNU Lesser General Public License as published by
the Free Software Foundation; either version 2.1 of the License, or
(at your option) any later version.
systemd is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/
#include <linux/filter.h>
#include "util.h"
#include "ipv4ll-internal.h"
int arp_network_send_raw_socket(int fd, const union sockaddr_union *link,
const struct ether_arp *arp) {
int r;
assert(arp);
assert(link);
assert(fd >= 0);
r = sendto(fd, arp, sizeof(struct ether_arp), 0, &link->sa, sizeof(link->ll));
if (r < 0)
return -errno;
return 0;
}
int arp_network_bind_raw_socket(int ifindex, union sockaddr_union *link) {
static const struct sock_filter filter[] = {
BPF_STMT(BPF_LD + BPF_W + BPF_LEN, 0), /* A <- packet length */
BPF_JUMP(BPF_JMP + BPF_JGE + BPF_K, sizeof(struct ether_arp), 1, 0), /* packet >= arp packet ? */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_hrd)), /* A <- header */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPHRD_ETHER, 1, 0), /* header == ethernet ? */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_pro)), /* A <- protocol */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ETHERTYPE_IP, 1, 0), /* protocol == IP ? */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
BPF_STMT(BPF_LD + BPF_H + BPF_ABS, offsetof(struct ether_arp, ea_hdr.ar_op)), /* A <- operation */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REQUEST, 0, 1), /* protocol == request ? */
BPF_STMT(BPF_RET + BPF_K, 65535), /* return all */
BPF_JUMP(BPF_JMP + BPF_JEQ + BPF_K, ARPOP_REPLY, 0, 1), /* protocol == reply ? */
BPF_STMT(BPF_RET + BPF_K, 65535), /* return all */
BPF_STMT(BPF_RET + BPF_K, 0), /* ignore */
};
struct sock_fprog fprog = {
.len = ELEMENTSOF(filter),
.filter = (struct sock_filter*) filter
};
_cleanup_close_ int s = -1;
int r;
assert(ifindex > 0);
assert(link);
s = socket(PF_PACKET, SOCK_DGRAM | SOCK_CLOEXEC | SOCK_NONBLOCK, 0);
if (s < 0)
return -errno;
r = setsockopt(s, SOL_SOCKET, SO_ATTACH_FILTER, &fprog, sizeof(fprog));
if (r < 0)
return -errno;
link->ll.sll_family = AF_PACKET;
link->ll.sll_protocol = htons(ETH_P_ARP);
link->ll.sll_ifindex = ifindex;
link->ll.sll_halen = ETH_ALEN;
memset(link->ll.sll_addr, 0xff, ETH_ALEN);
r = bind(s, &link->sa, sizeof(link->ll));
if (r < 0)
return -errno;
r = s;
s = -1;
return r;
}
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