void reply_payload(tw_rx_t * handle, tw_buf_t * buffer) {
struct ether_addr * dst_eth_addr;
struct ether_hdr * eth = buffer->data;
struct arp_hdr * arp_pkt =buffer->data + sizeof(struct ether_hdr);
switch (tw_be_to_cpu_16(eth->ether_type)) {
case ETHER_TYPE_ARP:
if (arp_flag == 1) {
tw_arp_parser(buffer, "tw0");
struct ether_addr * mac_addr = tw_search_arp_entry(ip);
if (mac_addr != NULL) {
dst_eth_addr = mac_addr;
printf("MAC address: %02X:%02X:%02X:%02X:%02X:%02X\n",
dst_eth_addr->addr_bytes[0],
dst_eth_addr->addr_bytes[1],
dst_eth_addr->addr_bytes[2],
dst_eth_addr->addr_bytes[3],
dst_eth_addr->addr_bytes[4],
dst_eth_addr->addr_bytes[5]);
arp_flag = -1;
exit(0);
}
}
}
tw_free_pkt(buffer);
}
void reply_udp_payload(tw_rx_t * handle, tw_buf_t * buffer) {
eth = buffer->data;
eth_type = tw_be_to_cpu_16(eth->ether_type);
switch (eth_type) {
case ETHER_TYPE_ARP:
tw_arp_parser(buffer, "tw0");
break;
case ETHER_TYPE_IPv4:
ipHdr_d = buffer->data + sizeof(struct ether_hdr);
dst_ip = (ipHdr_d->dst_addr);
src_ip = (ipHdr_d->src_addr);
ipHdr_d->dst_addr = (src_ip);
ipHdr_d->src_addr = (dst_ip);
ipHdr_d->hdr_checksum = tw_ipv4_cksum(ipHdr_d);
udp_hdr_d = (struct udp_hdr *)ipHdr_d + sizeof(struct ipv4_hdr);
dst_port = (udp_hdr_d->dst_port);
src_port = (udp_hdr_d->src_port);
udp_hdr_d->dst_port = (src_port);
udp_hdr_d->src_port = (dst_port);
udp_hdr_d->dgram_cksum = 0;
tw_copy_ether_addr(&(eth->s_addr), &(eth->d_addr));
tw_copy_ether_addr(dst_eth, &(eth->s_addr));
tw_send_pkt(buffer, "tw0");
break;
}
}
void pkt_rx(tw_rx_t * handle, tw_buf_t * buffer) {
eth = buffer->data;
if(tw_be_to_cpu_16(eth->ether_type) == ETHER_TYPE_ARP) {
global_stats_option.pkts_rx--;
tw_arp_parser(buffer, "tw0");
}
tw_free_pkt(buffer);
return;
}
/* reply_udp_payload acts as udp server; switches the IP and ports, mac addresses and echoes back the packet to sender*/
void reply_udp_payload(tw_rx_t * handle, tw_buf_t * buffer)
{
test_stats.datagrams_recv++;
eth = buffer->data;
eth_type = tw_be_to_cpu_16(eth->ether_type);
ipHdr_d = buffer->data + sizeof(struct ether_hdr);
dst_ip = (ipHdr_d->dst_addr);
src_ip = (ipHdr_d->src_addr);
ipHdr_d->dst_addr = (src_ip);
ipHdr_d->src_addr = (dst_ip);
ipHdr_d->hdr_checksum = tw_ipv4_cksum(ipHdr_d);
udp_hdr_d = (struct udp_hdr *) ipHdr_d + sizeof(struct ipv4_hdr);
dst_port = (udp_hdr_d->dst_port);
src_port = (udp_hdr_d->src_port);
udp_hdr_d->dst_port = (src_port);
udp_hdr_d->src_port = (dst_port);
udp_hdr_d->dgram_cksum = 0;
tw_copy_ether_addr(&(eth->s_addr), &(eth->d_addr));
tw_copy_ether_addr(test.server_mac, &(eth->s_addr));
tw_send_pkt(buffer, "tw0");
test_stats.datagrams_sent++;
}
