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// L2TPNS: arp
#include <string.h>
#include <unistd.h>
#include <net/ethernet.h>
#include <net/if_arp.h>
#include <linux/if_packet.h>
#include <netinet/ip6.h>
#include "dhcp6.h"
#include "l2tpns.h"
/* Most of this code is based on keepalived:vrrp_arp.c */
struct arp_buf {
struct ether_header eth;
struct arphdr arp;
/* Data bit - variably sized, so not present in |struct arphdr| */
unsigned char ar_sha[ETH_ALEN]; /* Sender hardware address */
in_addr_t ar_sip; /* Sender IP address. */
unsigned char ar_tha[ETH_ALEN]; /* Target hardware address */
in_addr_t ar_tip; /* Target ip */
} __attribute__((packed));
void sendarp(int ifr_idx, const unsigned char* mac, in_addr_t ip)
{
int fd;
struct sockaddr_ll sll;
struct arp_buf buf;
CSTAT(sendarp);
STAT(arp_sent);
/* Ethernet */
memset(buf.eth.ether_dhost, 0xFF, ETH_ALEN);
memcpy(buf.eth.ether_shost, mac, ETH_ALEN);
buf.eth.ether_type = htons(ETHERTYPE_ARP);
/* ARP */
buf.arp.ar_hrd = htons(ARPHRD_ETHER);
buf.arp.ar_pro = htons(ETHERTYPE_IP);
buf.arp.ar_hln = ETH_ALEN;
buf.arp.ar_pln = 4; //IPPROTO_ADDR_LEN;
buf.arp.ar_op = htons(ARPOP_REQUEST);
/* Data */
memcpy(buf.ar_sha, mac, ETH_ALEN);
memcpy(&buf.ar_sip, &ip, sizeof(ip));
memcpy(buf.ar_tha, mac, ETH_ALEN);
memcpy(&buf.ar_tip, &ip, sizeof(ip));
/* Now actually send the thing */
fd = socket(PF_PACKET, SOCK_RAW, htons(ETH_P_RARP));
memset(&sll, 0, sizeof(sll));
sll.sll_family = AF_PACKET;
memcpy(sll.sll_addr, mac, sizeof(sll.sll_addr) - 1);
sll.sll_halen = ETH_ALEN;
sll.sll_ifindex = ifr_idx;
sendto(fd, &buf, sizeof(buf), 0, (struct sockaddr*)&sll, sizeof(sll));
close(fd);
}
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