// raw_sock.c
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<netinet/ip.h>
#include<sys/socket.h>
#include<arpa/inet.h>

int main() {
	// Structs that contain source IP addresses
	struct sockaddr_in source_socket_address, dest_socket_address;

             int packet_size;

	// Allocate string buffer to hold incoming packet data
           unsigned char *buffer = (unsigned char *)malloc(65536);
	   // Open the raw socket
	   int sock = socket (PF_INET, SOCK_RAW, IPPROTO_TCP);
	   if(sock == -1)
	   {
             //socket creation failed, may be because of non-root privileges
             perror("Failed to create socket");
             exit(1);
           }
           while(1) {
             // recvfrom is used to read data from a socket
             packet_size = recvfrom(sock , buffer , 65536 , 0 , NULL, NULL);
             if (packet_size == -1) {
               printf("Failed to get packets\n");
               return 1;
             }

             struct iphdr *ip_packet = (struct iphdr *)buffer;

             memset(&source_socket_address, 0, sizeof(source_socket_address));
	     source_socket_address.sin_addr.s_addr = ip_packet->saddr;
             memset(&dest_socket_address, 0, sizeof(dest_socket_address));
             dest_socket_address.sin_addr.s_addr = ip_packet->daddr;

             printf("Incoming Packet: \n");
             printf("Packet Size (bytes): %d\n",ntohs(ip_packet->tot_len));
             printf("Source Address: %s\n", (char *)inet_ntoa(source_socket_address.sin_addr));
             printf("Destination Address: %s\n", (char *)inet_ntoa(dest_socket_address.sin_addr));
             printf("Identification: %d\n\n", ntohs(ip_packet->id));
           }

           return 0;
}