void
arpModel() {
int n;
// puts("----->ARP: Ready for requests...");
while (1) {
// rset = allset;
FD_ZERO(&rset);
FD_SET(un_listenfd, &rset);
FD_SET(if_sockfd, &rset);
maxfd = max(un_listenfd, if_sockfd);
if (un_connfd != -1){
printf("Add un_connfd to fs_set %d\n", un_connfd);
FD_SET(un_connfd, &rset);
maxfd = (maxfd, un_connfd);
}
Select(maxfd + 1, &rset, NULL, NULL, NULL);
if (FD_ISSET(un_listenfd, &rset)) {
// puts("----->ARP: Request to establish domain socket connection.");
accept_conn(un_listenfd);
}
if (un_connfd != -1 && FD_ISSET(un_connfd, &rset)) {
struct hwaddr hwaddr_info;
bzero(&hwaddr_info, sizeof(struct hwaddr));
if ((n = recv_un(un_connfd, &hwaddr_info)) > 0) {
// puts("----->ARP: Incoming un_packet. Handing over...");
// printf("Requested IP is: %s\n", hwaddr_info.sll_ip);
process_un(un_connfd, &hwaddr_info);
} else if(n == 0) {
puts("----->ARP: Time out.");
close(un_connfd);
un_connfd = -1;
}
}
if (FD_ISSET(if_sockfd, &rset)) {
struct arp_msg msg;
bzero(&msg, sizeof(struct arp_msg));
if ((n = recv_arp(if_sockfd, &msg)) == 0) {
// puts("*********MSG received***********");
// print_msg(&msg);
if (msg.op == ARP_REQ) {
// puts("----->ARP: Incoming PF_PACKET: ARP request. Handing over...");
process_arp_request(if_sockfd, &msg);
} else if (msg.op == ARP_REP) {
// puts("----->ARP: Incoming PF_PACKET: ARP reply. Handing over...");
process_arp_reply(if_sockfd, &msg);
}
}
}
}
}
int get_remote_mac(pcap_t *cap_dev, const u_char *if_addr, u_long sip, u_long dip, u_char *remote_mac) {
u_char arp_packet[sizeof(struct ethhdr) + sizeof(arphdr_ether)];
struct pcap_pkthdr *header;
const u_char *pkt_data;
int res = 0;
/* In case we fail */
memset(remote_mac, 0, ETH_ALEN);
/* Build the ARP request packet */
generate_arp_request(arp_packet, if_addr, sip, dip);
/* Send the ARP request */
/* There's a race condition here because the reply might arrive before we capture it */
if (pcap_sendpacket(cap_dev, arp_packet, sizeof(arp_packet)) != 0)
return -1;
int timeouts = 0;
int packets = 0;
/* Start the capture */
while ((res = pcap_next_ex(cap_dev, &header, &pkt_data)) >= 0)
{
//static int timeouts = 0;
//static int packets = 0;
/* Timeout elapsed? */
if (res == 0) {
if (++timeouts > CAP_MAX_TIMEOUTS)
break;
}
else {
/* Look for the ARP reply (source and destination are reversed) */
if (process_arp_reply(header, pkt_data, dip, sip, remote_mac) == 0)
{
printf("t:%d, p:%d\t",timeouts,packets);
return 0;
}
/* Seen too many packets without finding ours? */
if (++packets >= CAP_MAX_PACKETS)
break;
}
}
/* Didn't receive the appropriate ARP reply */
return -2;
}
void process_arp_packet( struct sr_instance *sr, const uint8_t *packet, unsigned int len, const char *interface) {
assert(sr);
assert(packet);
assert(interface);
arp_hdr *arp_packet = get_arp_hdr(packet, len);
switch(ntohs(arp_packet->arp_op)) {
case ARP_OP_REQUEST:
process_arp_request(sr, packet, len, interface);
break;
case ARP_OP_REPLY:
process_arp_reply(sr, packet, len, interface);
break;
default: return;
}
}
