void handle_arpreq(struct sr_instance *sr, struct sr_arpreq *req) {
time_t now = time(NULL);
if (difftime(now, req->sent) >= 0.9) {
if (req->times_sent >= 5) {
struct sr_packet *pkt_pending = req->packets;
struct sr_if *interface = sr_get_interface(sr, pkt_pending->iface);
while (pkt_pending) {
icmp_handler(sr, pkt_pending->buf, 0, interface->ip, HOST_UNREACHABLE);
pkt_pending = pkt_pending->next;
}
sr_arpreq_destroy(&(sr->cache), req);
}
else {
int packet_len = sizeof(sr_ethernet_hdr_t) + sizeof(sr_arp_hdr_t);
uint8_t *pkt = malloc(packet_len);
struct sr_ethernet_hdr *eth_hdr = (struct sr_ethernet_hdr *)pkt;
struct sr_if *interface = sr_get_interface(sr, req->packets->iface);
uint8_t hrd_addr[ETHER_ADDR_LEN] = {0xFF, 0xFF, 0xFF, 0xFF, 0xFF, 0xFF};
enum sr_ethertype eth_arp = ethertype_arp;
enum sr_ethertype eth_ip = ethertype_ip;
memcpy(eth_hdr->ether_dhost, hrd_addr, ETHER_ADDR_LEN);
memcpy(eth_hdr->ether_shost, interface->addr, ETHER_ADDR_LEN);
eth_hdr->ether_type = htons(eth_arp);
struct sr_arp_hdr *arp_hdr = (struct sr_arp_hdr *)(sizeof(sr_ethernet_hdr_t) + pkt);
enum sr_arp_hrd_fmt hrd_eth = arp_hrd_ethernet;
enum sr_arp_opcode arp_op_req = arp_op_request;
arp_hdr->ar_hrd = htons(hrd_eth);
arp_hdr->ar_pro = htons(eth_ip);
arp_hdr->ar_hln = ETHER_ADDR_LEN;
arp_hdr->ar_pln = 4;
arp_hdr->ar_op = htons(arp_op_req);
arp_hdr->ar_sip = interface->ip;
arp_hdr->ar_tip = req->ip;
memcpy(arp_hdr->ar_sha, interface->addr, ETHER_ADDR_LEN);
memcpy(arp_hdr->ar_tha, hrd_addr, ETHER_ADDR_LEN);
printf("Sending Packets.. [3].\n");
sr_send_packet(sr, pkt, packet_len, interface->name);
free(pkt);
req->sent = now;
req->times_sent++;
}
}
}
/*
* @brief Handles ip packets
* @param skb Pointer to the skb, whose data pointer must be set to ip header.
* @return 0 on success. -1 on failure. The packet is freed in both cases
*/
int ip_handler(struct sk_buff *skb)
{
int ret = -1;
struct ip_hdr *iph;
struct pal_dip *dip;
if (!skb_ip_csum_ok(skb)) {
PAL_DEBUG("skb ip csum error\n");
pal_cur_thread_conf()->stats.ip.csum_err++;
goto free_out;
}
iph = skb_ip_header(skb);
if ((unsigned)iph->ihl < 5 || skb_len(skb) < (unsigned)iph->ihl * 4) {
pal_cur_thread_conf()->stats.ip.trunc_pkts++;
goto free_out;
}
dip = pal_ipg_find_ip(iph->daddr);
if (dip == NULL) {
pal_cur_thread_conf()->stats.ip.unknown_dst++;
/* TODO: use default ip group. */
PAL_DEBUG("dip "NIPQUAD_FMT" not found\n", NIPQUAD(iph->daddr));
goto free_out;
}
switch (dip->type) {
case PAL_DIP_USER:
skb_pull(skb, iph->ihl * 4);
skb_reset_l4_header(skb);
switch (iph->protocol) {
case PAL_IPPROTO_TCP:
ret = tcp_dispatch(skb, dip);
break;
case PAL_IPPROTO_UDP:
ret = udp_dispatch(skb, dip);
break;
case PAL_IPPROTO_ICMP:
if (dip->ipg->flags & PAL_IPG_F_HANDLEICMP) {
ret = icmp_dispatch(skb, dip);
} else {
ret = icmp_handler(skb);
}
break;
default:
pal_cur_thread_conf()->stats.ip.unknown_proto_pkts++;
pal_cur_thread_conf()->stats.ip.unknown_proto_bytes += skb_l2_len(skb);
PAL_DEBUG("UNKNOWN IP PKTS\n");
if (dip->ipg->flags & PAL_IPG_F_HANDLEUNKNOWIPPROTO) {
ret = dispatch_pkt(skb, dip);
} else {
ret = -1;
}
break;
}
if (ret >= 0) {
pal_ipg_put_ip(dip->ip);
return 0;
}
goto putdip_out;
case PAL_DIP_VNIC:
if (dip->port != skb->recv_if) {
pal_cur_thread_conf()->stats.tap.port_err++;
PAL_DEBUG("got a packet for wrong vnic\n");
goto putdip_out;
}
/* push the data pointer to include the ethernet header */
skb_push(skb, sizeof(struct eth_hdr));
if (pal_send_to_vnic(dip->port, skb) == 0) {
pal_skb_free(skb);
pal_ipg_put_ip(dip->ip);
return 0;
}
goto putdip_out;
default:
pal_cur_thread_conf()->stats.ip.unknown_dst++;
PAL_DEBUG("unknown\n");
goto putdip_out;
}
putdip_out:
pal_ipg_put_ip(dip->ip);
free_out:
pal_skb_free(skb);
return ret;
}