Merge from Master
[l2tpns.git] / arp.c
1 // L2TPNS: arp
2
3 #include <string.h>
4 #include <unistd.h>
5 #include <net/ethernet.h>
6 #include <net/if_arp.h>
7 #include <linux/if_packet.h>
8 #include <linux/rtnetlink.h>
9 #include <netinet/ip6.h>
10
11 #include "dhcp6.h"
12 #include "l2tpns.h"
13
14 /* Most of this code is based on keepalived:vrrp_arp.c */
15
16 struct arp_buf {
17 struct ether_header eth;
18 struct arphdr arp;
19
20 /* Data bit - variably sized, so not present in |struct arphdr| */
21 unsigned char ar_sha[ETH_ALEN]; /* Sender hardware address */
22 in_addr_t ar_sip; /* Sender IP address. */
23 unsigned char ar_tha[ETH_ALEN]; /* Target hardware address */
24 in_addr_t ar_tip; /* Target ip */
25 } __attribute__((packed));
26
27 void sendarp(int ifr_idx, const unsigned char* mac, in_addr_t ip)
28 {
29 int fd;
30 struct sockaddr_ll sll;
31 struct arp_buf buf;
32
33 CSTAT(sendarp);
34 STAT(arp_sent);
35
36 /* Ethernet */
37 memset(buf.eth.ether_dhost, 0xFF, ETH_ALEN);
38 memcpy(buf.eth.ether_shost, mac, ETH_ALEN);
39 buf.eth.ether_type = htons(ETHERTYPE_ARP);
40
41 /* ARP */
42 buf.arp.ar_hrd = htons(ARPHRD_ETHER);
43 buf.arp.ar_pro = htons(ETHERTYPE_IP);
44 buf.arp.ar_hln = ETH_ALEN;
45 buf.arp.ar_pln = 4; //IPPROTO_ADDR_LEN;
46 buf.arp.ar_op = htons(ARPOP_REQUEST);
47
48 /* Data */
49 memcpy(buf.ar_sha, mac, ETH_ALEN);
50 memcpy(&buf.ar_sip, &ip, sizeof(ip));
51 memcpy(buf.ar_tha, mac, ETH_ALEN);
52 memcpy(&buf.ar_tip, &ip, sizeof(ip));
53
54 /* Now actually send the thing */
55 fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_RARP));
56
57 memset(&sll, 0, sizeof(sll));
58 sll.sll_family = AF_PACKET;
59 memcpy(sll.sll_addr, mac, sizeof(sll.sll_addr) - 1);
60 sll.sll_halen = ETH_ALEN;
61 sll.sll_ifindex = ifr_idx;
62
63 sendto(fd, &buf, sizeof(buf), 0, (struct sockaddr*)&sll, sizeof(sll));
64 close(fd);
65 }