void sr_handleARPpacket(struct sr_instance *sr, uint8_t* packet, unsigned int len, struct sr_if * iface) {
assert(packet);
sr_ethernet_hdr_t* ethHeader = (sr_ethernet_hdr_t*) packet;
sr_arp_hdr_t * arpHeader = (sr_arp_hdr_t *) (packet+14);
enum sr_arp_opcode request = arp_op_request;
enum sr_arp_opcode reply = arp_op_reply;
struct sr_if *interface = sr_get_interface_from_ip(sr, htonl(arpHeader->ar_tip));
/* handle an arp request.*/
if (ntohs(arpHeader->ar_op) == request) {
/* found an ip->mac mapping. send a reply to the requester's MAC addr */
if (interface){
arpHeader->ar_op = ntohs(reply);
uint32_t temp = arpHeader->ar_sip;
arpHeader->ar_sip = arpHeader->ar_tip;
arpHeader->ar_tip = temp;
memcpy(arpHeader->ar_tha, arpHeader->ar_sha,6);
memcpy(arpHeader->ar_sha, iface->addr,6);
/*swapping outgoing and incoming addr*/
set_addr(ethHeader, iface->addr, ethHeader->ether_shost);
sr_send_packet(sr,(uint8_t*)ethHeader,len,iface->name);
}
}
/* handle an arp reply */
else {
struct sr_packet *req_packet = NULL;
struct sr_arpreq *req = NULL;
pthread_mutex_lock(&(sr->cache.lock));
for (req = sr->cache.requests; req != NULL; req = req->next){
if(req->ip == arpHeader->ar_sip){
/* find the interface the packets should be sent out of */
struct sr_rt * rt = (struct sr_rt *)sr_find_routing_entry_int(sr, req->ip);
if (rt) {
iface = sr_get_interface(sr, rt->interface);
/* send all packets waiting on the request that was replied to */
for (req_packet = req->packets; req_packet != NULL; req_packet = req_packet->next) {
sr_ethernet_hdr_t * outEther = (sr_ethernet_hdr_t *)req_packet->buf;
memcpy(outEther->ether_shost, iface->addr,6);
memcpy(outEther->ether_dhost, ethHeader->ether_shost,6);
sr_ip_hdr_t * outIP = (sr_ip_hdr_t *)(req_packet->buf+14);
outIP->ip_ttl = outIP->ip_ttl-1;
outIP->ip_sum = 0;
outIP->ip_sum = cksum((uint8_t *)outIP,20);
sr_send_packet(sr,req_packet->buf,req_packet->len,iface->name);
}
sr_arpreq_destroy(&(sr->cache), req);
}
break;
}
}
pthread_mutex_unlock(&(sr->cache.lock));
sr_arpcache_insert(&(sr->cache),arpHeader->ar_sha,arpHeader->ar_sip);
}
}
void handle_arp_reply(struct sr_instance *sr, uint8_t* ethernet_data_addr, struct sr_if* in_f){
printf("in handle arp reply\n");
/*
The ARP reply processing code should move entries from the ARP request
queue to the ARP cache:
# When servicing an arp reply that gives us an IP->MAC mapping
req = arpcache_insert(ip, mac)
if req:
send all packets on the req->packets linked list
arpreq_destroy(req)
*/
/*Loop through sr_cache requests and look for an IP match to the ARP header source IP*/
sr_arp_hdr_t *arp_header = (sr_arp_hdr_t *) ethernet_data_addr;
struct sr_arpreq *req_ptr = sr_arpcache_insert(&(sr->cache), arp_header->ar_sha, arp_header->ar_sip);
/*If the IP in the reply matched something in our request queue*/
if (req_ptr) {
struct sr_packet *req_pkts = req_ptr->packets;
struct sr_packet *req_pkt_ptr = req_pkts;
for (; req_pkt_ptr; req_pkt_ptr = req_pkt_ptr->next) {
sr_ethernet_hdr_t *packet_eth_hdr = (sr_ethernet_hdr_t *) req_pkts->buf;
sr_ip_hdr_t *packet_ip_hdr = (sr_ip_hdr_t *) (req_pkts->buf + sizeof(sr_ethernet_hdr_t));
/*ret_if will be populated if this was originally an echo request, else 0*/
struct sr_if* ret_if = sr_get_interface_from_ip(sr, packet_ip_hdr->ip_dst);
if (ret_if) {
/*Doesn't have a code so just passing 0 as code*/
send_icmp_echo_reply(sr, (uint8_t *) packet_eth_hdr, req_pkt_ptr->len, in_f, arp_header->ar_sha, echo_reply_type, 0);
}
else {
memcpy(packet_eth_hdr->ether_dhost, arp_header->ar_sha, ETHER_ADDR_LEN);
sr_send_packet(sr, (uint8_t *) packet_eth_hdr, req_pkt_ptr->len, in_f->name);
}
}
sr_arpreq_destroy(&(sr->cache), req_ptr);
}
/*Otherwise do nothing, the reply wasn't about anything in our queue*/
}
/*Returns 0 on success and error code on fail*/
int sr_handlearp(struct sr_instance** sr, uint8_t** ethernet_data_addr, struct sr_if* in_f, unsigned int len){
uint8_t *eth_pkt_buf;
uint8_t *arp_pkt_buf; /* ARP packet buffer */
struct sr_if* ret_if; /* return interface */
printf("sr_handlearp");
sr_arp_hdr_t* arp_header_buffer = (sr_arp_hdr_t*)*ethernet_data_addr;
ntoh_arp_hdr(&arp_header_buffer); /* converts header members into host byte order where appropriate */
/* Recieved ARP request! Reply to request. */
if(arp_header_buffer->ar_op == arp_op_request) {
if ((ret_if = sr_get_interface_from_ip(*sr, arp_header_buffer->ar_tip))) { /* Target IP is IP of a Router Interface*/
/* Send an ARP reply (uint8_t*) */
/* Create reply frame */
eth_pkt_buf = (uint8_t *) malloc(sizeof(sr_ethernet_hdr_t) + sizeof(sr_arp_hdr_t)); /* Allocate mem for reply packet buffer */
sr_ethernet_hdr_t *req_reply_eth_header = (sr_ethernet_hdr_t *) eth_pkt_buf;
/* Build Ethernet Header */
memcpy(req_reply_eth_header->ether_dhost, arp_header_buffer->ar_sha, ETHER_ADDR_LEN);
memcpy(req_reply_eth_header->ether_shost, in_f->addr, ETHER_ADDR_LEN);
req_reply_eth_header->ether_type = ethertype_arp;
/* Convert to network byte ordering */
hton_eth_hdr(&req_reply_eth_header);
/* Get the Arp Buffer and Build the Arp packet*/
arp_pkt_buf = eth_pkt_buf + sizeof(sr_ethernet_hdr_t);
sr_create_arp_packet(&arp_pkt_buf, arp_header_buffer, ret_if); /* Create arp packet to be sent as ARP reply, fill arp_pkt_buf with ARP reply header data */
/* Send the ARP reply packet */
sr_send_packet(*sr, eth_pkt_buf, sizeof(sr_ethernet_hdr_t) + sizeof(sr_arp_hdr_t), in_f->name);
free(eth_pkt_buf);
} else { /* Target IP is *NOT* IP of a Router Interface */
/* I'm not sure what to do here yet MAYBE NOTHING?!*/
}
}
else if (arp_header_buffer->ar_op == arp_op_reply) {
handle_arp_reply(*sr, *ethernet_data_addr, in_f);
}
return 0;
}
void sr_handle_ip(struct sr_instance *sr, uint8_t *packet, unsigned int len, struct sr_if *iface)
{
assert(sr);
assert(packet);
assert(iface);
if (len < sizeof(sr_ethernet_hdr_t) + sizeof(sr_ip_hdr_t)) {
fprintf(stderr, "Failed to process IP header, insufficient length\n");
return;
}
sr_ip_hdr_t *ip_hdr = (sr_ip_hdr_t *)(packet + sizeof(sr_ethernet_hdr_t));
if (len < sizeof(sr_ethernet_hdr_t) + (ip_hdr->ip_hl * 4)) {
fprintf(stderr, "Failed to process IP header, insufficient length\n");
return;
}
/* verify checksum */
uint16_t received_cksum = ip_hdr->ip_sum;
ip_hdr->ip_sum = 0;
uint16_t computed_cksum = cksum(ip_hdr, ip_hdr->ip_hl * 4);
ip_hdr->ip_sum = received_cksum;
if (received_cksum != computed_cksum) {
fprintf(stderr, "Failed to process IP header, incorrect checksum\n");
return;
}
struct sr_if *diface = sr_get_interface_from_ip(sr, ip_hdr->ip_dst);
if (!diface) {
sr_forward_ip(sr, packet, len);
} else {
if (ip_hdr->ip_p == ip_protocol_icmp) {
sr_handle_icmp(sr, packet, len);
} else if (ip_hdr->ip_p == 0x0006 || ip_hdr->ip_p == 0x0011) {
sr_send_icmp(sr, packet, len, 3, 3);
}
}
}
void sr_natHandleIP(struct sr_instance* sr, uint8_t* packet,unsigned int len, struct sr_if * iface){
assert(packet);
sr_ethernet_hdr_t* ethHeader = (sr_ethernet_hdr_t*) packet;
uint8_t* ip_packet = packet+sizeof(sr_ethernet_hdr_t);
sr_ip_hdr_t * ipHeader = (sr_ip_hdr_t *) (ip_packet);
uint16_t incm_cksum = ipHeader->ip_sum;
ipHeader->ip_sum = 0;
uint16_t currentChecksum = cksum(ip_packet,20);
ipHeader->ip_sum = incm_cksum;
uint8_t* icmp_packet;
/* if the destination address is one of my interfaces */
if (currentChecksum==incm_cksum && sr_get_interface_from_ip(sr,ntohl(ipHeader->ip_dst)) != NULL){
/* check cache for ip->mac mapping for next hop */
/*struct sr_arpentry *entry;
entry = sr_arpcache_lookup(&sr->cache, ipHeader->ip_dst);
struct sr_rt * rt = (struct sr_rt *)sr_find_routing_entry_int(sr, ipHeader->ip_dst);
*/
/* found next hop. send packet */
if (ipHeader->ip_ttl <= 1){ /* IP TTL died. send ICMP type 11, code 0 */
icmp_packet = createICMP(11, 0, ip_packet,len-14);
memcpy(ip_packet+20,icmp_packet,sizeof(sr_icmp_t3_hdr_t));
ipHeader->ip_p = 1;
ipHeader->ip_len = htons(20+8+(len-34<28?len-34:28));
free(icmp_packet);
} else if(ipHeader->ip_p==6){ /* IP TCP */
icmp_packet = createICMP(3,3,ip_packet,len-14);
memcpy(ip_packet+20,icmp_packet,sizeof(sr_icmp_t3_hdr_t));
ipHeader->ip_p = 1;
ipHeader->ip_len = htons(20+8+(len-34<28?len-34:28));
free(icmp_packet);
}else if(ipHeader->ip_tos==0 && ipHeader->ip_p==1){ /* IP ping */
sr_icmp_hdr_t * icmp_header = (sr_icmp_hdr_t *) (packet + sizeof(sr_ethernet_hdr_t) + sizeof(sr_ip_hdr_t));
incm_cksum = icmp_header->icmp_sum;
icmp_header->icmp_sum = 0;
currentChecksum = cksum(icmp_header,len - sizeof(sr_ethernet_hdr_t) - sizeof(sr_ip_hdr_t));
if(currentChecksum == incm_cksum && icmp_header->icmp_type == 8 && icmp_header->icmp_code == 0) {
icmp_header->icmp_type = 0;
ipHeader->ip_sum = 0;
icmp_header->icmp_sum = cksum(icmp_header,len - sizeof(sr_ethernet_hdr_t) - sizeof(sr_ip_hdr_t));
}
else{
printf("ICMP INVALID\n");
printf("%d != %d OR %d != %d\n",currentChecksum,incm_cksum, icmp_header->icmp_type, 8);
}
} else {
printf("IP Bad\n");
ip_packet = NULL;
}
}
else{
printf("IP INVALID\n");
ip_packet = NULL;
}
if(ip_packet){ /* send ICMP packet */
ipHeader->ip_dst = ipHeader->ip_src;
ipHeader->ip_src = iface->ip;
ipHeader->ip_ttl = 64;
ipHeader->ip_sum = 0;
ipHeader->ip_sum = cksum(ip_packet,20);
struct sr_arpentry *entry;
entry = sr_arpcache_lookup(&sr->cache, ipHeader->ip_dst);
struct sr_rt * rt = (struct sr_rt *)sr_find_routing_entry_int(sr, ipHeader->ip_dst);
if (entry && rt) { /* found next hop. send packet */
iface = sr_get_interface(sr, rt->interface);
set_addr(ethHeader, iface->addr, entry->mac);
sr_send_packet(sr,packet,len,iface->name);
free(entry);
ip_packet = NULL;
} else if (rt) { /* send an arp request to find out what the next hop should be */
struct sr_arpreq *req;
sr_arpcache_insert(&(sr->cache), ethHeader->ether_shost, ipHeader->ip_src);
req = sr_arpcache_queuereq(&(sr->cache), ipHeader->ip_dst, packet, len, iface->name);
/*handle_arpreq(sr, req);*/
ip_packet = NULL;
}
}
}
/*Returns 0 on success and error code on fail*/
int sr_handleip(struct sr_instance* sr,
uint8_t* packet,
unsigned int len,
struct sr_if* in_f,
uint8_t** ethernet_data_addr){
sr_ip_hdr_t* ip_header_buffer = (sr_ip_hdr_t*) *ethernet_data_addr;
/* Get headers from packet */
/*sr_ethernet_hdr_t* eth_hdr = (sr_ethernet_hdr_t*) packet;
uint8_t * ip_pkt_buf = packet + sizeof(sr_ethernet_hdr_t);
sr_ip_hdr_t* ip_hdr = (sr_ip_hdr_t*) (packet + sizeof(sr_ethernet_hdr_t)); */
uint8_t * icmp_pkt_buf = packet + sizeof(sr_ethernet_hdr_t) + sizeof(sr_ip_hdr_t);
sr_icmp_hdr_t* icmp_hdr = (sr_icmp_hdr_t*) icmp_pkt_buf;
struct sr_if* ret_if; /* return interface */
if (check_ip_sum(ip_header_buffer) == 0) { /*Pass Checksum*/
printf("Checksum Pass\n");
}
else { /*Fail Checksum*/
printf("Checksum Fail\n");
return -1;
}
/*If the TTL went to 0*/
if (decrement_ttl(ip_header_buffer) == -1) {
/*Send ICMP with the proper TTL decrease type and icmp code*/
printf("TTL reached 0\n");
send_icmp(sr, packet, len, in_f, time_exceed_type, time_exceed_code);
return -1;
}
/*Check if the IP packet is for us and not a echo request*/
ret_if = sr_get_interface_from_ip(sr, ip_header_buffer->ip_dst);
if(ret_if && !(ip_header_buffer->ip_p == ip_protocol_icmp &&
icmp_hdr->icmp_type == echo_req_type && icmp_hdr->icmp_code == echo_req_code)) {
/* The IP packet is FOR US */
printf("FOR US, NOT ECHO REQ");
/* Check if it is an echo request */
if (ip_header_buffer->ip_p == ip_protocol_tcp ||
ip_header_buffer->ip_p == ip_protocol_udp) {
/* It is TCP/UDP send ICMP port unreachable
SEND: an ICMP port unreachable to sending host*/
send_icmp(sr, packet, len, in_f, port_unreach_type, port_unreach_code);
} else {
;
/* According to the Assignment: IGNORE THE PACKET*/
}
} else {
/*If it's not in the routing table, send ICMP net unreachable*/
struct sr_rt * routing_node;
uint32_t ip_dest;
/*If it's for us, we want to send back to the source, so check for the source in the routing table*/
if (ret_if) {
/* The IP packet is FOR US */
printf("FOR US\n");
ip_dest = ip_header_buffer->ip_src;
}
/*If not for us, we want to keep forwarding to the destination so check for that in the routing table*/
else {
/* The IP packet is NOT FOR US */
printf("NOT FOR US\n");
ip_dest = ip_header_buffer->ip_dst;
}
if ((routing_node = check_routing_table(sr, ip_dest)) == NULL) {
printf("NOT in routing table\n");
send_icmp(sr, packet, len, in_f, dest_net_unreach_type, dest_net_unreach_code);
}
else {
printf("In routing table\n");
/*Got the routing table node in routing_node */
/*Next hop IP address is in gateway
*Look it up in arpcache_lookup to see if we know the MAC address
*/
uint32_t nexthopIP = routing_node->gw.s_addr;
struct sr_arpentry *arp_dest = sr_arpcache_lookup(&(sr->cache), nexthopIP);
struct sr_if* nexthopInterface = sr_get_interface(sr, routing_node->interface);
/*Create an ethernet header in front of the packet to forward regardless of
whether or not we've found the next hop IP: need it in both cases*/
/*Allocate space for ethernet header and packet, copy in contents of packet*/
uint8_t* eth_header_packet = malloc(len);
uint8_t* ip_header = eth_header_packet + sizeof(sr_ethernet_hdr_t);
uint8_t* only_packet = eth_header_packet + sizeof(sr_ethernet_hdr_t) + sizeof(sr_ip_hdr_t);
memcpy(ip_header, ip_header_buffer, sizeof(sr_ip_hdr_t));
memcpy(only_packet, (packet+sizeof(sr_ethernet_hdr_t)+sizeof(sr_ip_hdr_t)), len-sizeof(sr_ethernet_hdr_t)-sizeof(sr_ip_hdr_t));
/*Save it in struct form*/
sr_ethernet_hdr_t* packet_to_forward = (sr_ethernet_hdr_t*)eth_header_packet;
/*Now set the actual ethernet header for the packet*/
packet_to_forward->ether_type = htons(ethertype_ip);
memcpy(packet_to_forward->ether_shost, nexthopInterface->addr, ETHER_ADDR_LEN);
/*If NULL, send out the arp request*/
if(arp_dest == NULL){
printf("Not in arp cache: need to send an ARP request!\n");
broadcast_arp_req(sr, nexthopIP, packet_to_forward, len, routing_node, nexthopInterface);
}
/*Otherwise just forward the packet to arp_dest's MAC address*/
else {
/*It's for us, it must be an echo request*/
if (ret_if) {
/*Doesn't have a code so just passing 0 as code*/
struct sr_if *interface = sr_get_interface(sr, routing_node->interface);
send_icmp_echo_reply(sr, packet, len, interface, arp_dest->mac, echo_reply_type, 0);
}
else {
printf("In arp cache: just forwarding the packet\n");
memcpy(packet_to_forward->ether_dhost, arp_dest->mac, ETHER_ADDR_LEN);
sr_send_packet(sr, (uint8_t*)packet_to_forward, len, routing_node->interface);
/*Free the arp_dest that sr_arpcache_lookup created*/
free(arp_dest);
}
}
}
}
return 0;
}
void sr_handle_arp(struct sr_instance *sr, uint8_t *packet, unsigned int len, struct sr_if *iface)
{
assert(sr);
assert(packet);
assert(iface);
/* check length */
if (len < sizeof(sr_ethernet_hdr_t) + sizeof(sr_arp_hdr_t)) {
fprintf(stderr, "Failed to process ARP header, insufficient length\n");
return;
}
sr_arp_hdr_t *arp_hdr = (sr_arp_hdr_t *)(packet + sizeof(sr_ethernet_hdr_t));
/* print_hdr_arp((uint8_t *)arp_hdr); */
/* check hardware type */
if (ntohs(arp_hdr->ar_hrd) != arp_hrd_ethernet) {
return;
}
/* check protocol */
if (ntohs(arp_hdr->ar_pro) != ethertype_ip) {
return;
}
/* is it for me? */
struct sr_if *tiface = sr_get_interface_from_ip(sr, arp_hdr->ar_tip);
if (!tiface) {
return;
}
unsigned short arp_op = ntohs(arp_hdr->ar_op);
if (arp_op == arp_op_request) {
sr_send_arp_reply(sr, packet, iface, tiface);
} else if (arp_op == arp_op_reply) {
struct sr_arpreq *req = sr_arpcache_insert(&(sr->cache), arp_hdr->ar_sha, arp_hdr->ar_sip);
if (req) {
struct sr_packet *pkt = NULL;
struct sr_if *oiface = NULL;
sr_ethernet_hdr_t *eth_hdr = NULL;
pkt = req->packets;
while (pkt) {
oiface = sr_get_interface(sr, pkt->iface);
eth_hdr = (sr_ethernet_hdr_t *)(pkt->buf);
memcpy(eth_hdr->ether_dhost, arp_hdr->ar_sha, ETHER_ADDR_LEN);
memcpy(eth_hdr->ether_shost, oiface->addr, ETHER_ADDR_LEN);
sr_send_packet(sr, pkt->buf, pkt->len, pkt->iface);
pkt = pkt->next;
}
sr_arpreq_destroy(&(sr->cache), req);
}
}
} /* -- sr_handle_arp -- */
