void processIP(struct sr_instance* sr,
uint8_t * packet,
unsigned int len,
char* interface) {
struct sr_ip_hdr *ipHeader = (struct sr_ip_hdr *) (packet + sizeof(struct sr_ethernet_hdr));
ipHeader->ip_ttl--;
if (ipHeader->ip_p == ip_protocol_icmp) {
/* ICMP request */
/* Ignore invalid packets */
if (!is_sane_icmp_packet(packet, len)) {
return;
}
/* Process ICMP only if echo*/
struct sr_icmp_hdr *icmpHeader = (struct sr_icmp_hdr *)(packet + sizeof(struct sr_ethernet_hdr) + sizeof(struct sr_ip_hdr));
if (icmpHeader->icmp_type == icmp_echo_req_type) {
icmp_send_echo_reply(sr, packet, len, interface);
}
} else if (ipHeader->ip_p == ip_protocol_tcp || ipHeader->ip_p == ip_protocol_udp) {
/* TCP or UDP Payload */
icmp_send_port_unreachable(sr, packet, len, interface);
}
}
void ip_handle_incoming_packet(struct sr_packet * packet)
{
struct ip * ip_hdr = IP_HDR(packet);
if(ip_hdr->ip_sum != checksum_ipheader(ip_hdr))
{
printf("\nchecksums differ %x, %x\n", ip_hdr->ip_sum, checksum_ipheader(ip_hdr));
}
else if(ip_hdr->ip_v != 4)
{
printf("\nip version is %d; only accepting 4\n",ip_hdr->ip_v);
}
else
{
if(dhcp_packet(packet))
{
dhcp_handle_incoming(packet);
}
/* if packet is not for one of our interfaces then forward */
else if(!interface_list_ip_exists(ROUTER(packet->sr)->iflist, ip_hdr->ip_dst.s_addr) &&
ntohl(ip_hdr->ip_dst.s_addr) != OSPF_AllSPFRouters)
{
if(ip_hdr->ip_ttl <= 1)
{
icmp_send_time_exceeded(packet);
}
else
{
if(ip_hdr->ip_p == IP_P_TCP || ip_hdr->ip_p == IP_P_UDP)
{
tcp_handle_incoming_not_for_us(packet);
}
else
{
ip_forward(packet);
}
}
}
else
{
switch(ip_hdr->ip_p)
{
case IP_P_ICMP:
icmp_handle_incoming_packet(packet);
break;
case IP_P_TCP: case IP_P_UDP:
tcp_handle_incoming_for_us(packet);
break;
case IP_P_OSPF:
ospf_handle_incoming_packet(packet);
break;
default:
icmp_send_port_unreachable(packet);
}
}
}
}
