* Update cli callbacks to work with libcli 1.6.
[l2tpns.git] / arp.c
1 // L2TPNS: arp
2
3 char const *cvs_id_arp = "$Id: arp.c,v 1.3 2004-06-28 02:43:13 fred_nerk Exp $";
4
5 #include <string.h>
6 #include <unistd.h>
7 #include <net/ethernet.h>
8 #include <net/if_arp.h>
9 #include <linux/if_packet.h>
10
11 #include "l2tpns.h"
12
13 /* Most of this code is based on keepalived:vrrp_arp.c */
14
15 struct arp_buf {
16 struct ether_header eth;
17 struct arphdr arp;
18
19 /* Data bit - variably sized, so not present in |struct arphdr| */
20 unsigned char ar_sha[ETH_ALEN]; /* Sender hardware address */
21 ipt ar_sip; /* Sender IP address. */
22 unsigned char ar_tha[ETH_ALEN]; /* Target hardware address */
23 ipt ar_tip; /* Target ip */
24 } __attribute__((packed));
25
26 void sendarp(int ifr_idx, const unsigned char* mac, ipt ip)
27 {
28 int fd;
29 struct sockaddr_ll sll;
30 struct arp_buf buf;
31
32 /* Ethernet */
33 memset(buf.eth.ether_dhost, 0xFF, ETH_ALEN);
34 memcpy(buf.eth.ether_shost, mac, ETH_ALEN);
35 buf.eth.ether_type = htons(ETHERTYPE_ARP);
36
37 /* ARP */
38 buf.arp.ar_hrd = htons(ARPHRD_ETHER);
39 buf.arp.ar_pro = htons(ETHERTYPE_IP);
40 buf.arp.ar_hln = ETH_ALEN;
41 buf.arp.ar_pln = 4; //IPPROTO_ADDR_LEN;
42 buf.arp.ar_op = htons(ARPOP_REQUEST);
43
44 /* Data */
45 memcpy(buf.ar_sha, mac, ETH_ALEN);
46 memcpy(&buf.ar_sip, &ip, sizeof(ip));
47 memcpy(buf.ar_tha, mac, ETH_ALEN);
48 memcpy(&buf.ar_tip, &ip, sizeof(ip));
49
50 /* Now actually send the thing */
51 fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_RARP));
52
53 memset(&sll, 0, sizeof(sll));
54 sll.sll_family = AF_PACKET;
55 strncpy(sll.sll_addr, mac, sizeof(sll.sll_addr) - 1);
56 sll.sll_halen = ETH_ALEN;
57 sll.sll_ifindex = ifr_idx;
58
59 sendto(fd, &buf, sizeof(buf), 0, (struct sockaddr*)&sll, sizeof(sll));
60 close(fd);
61 }