#include <sys/types.h>
#define __FAVOR_BSD
#include <sys/socket.h>
#include <stdio.h>
#include <netdb.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <arpa/inet.h>
#include <string.h>
char data[1024] = "";
 
 
 
unsigned short csum(unsigned short *buf,int nwords)
{
	//this function returns the checksum of a buffer
	unsigned long sum;
	for (sum = 0; nwords > 0; nwords--){sum += *buf++;}
	sum = (sum >> 16) + (sum & 0xffff);
	sum += (sum >> 16);
	return (unsigned short) (~sum);
}
 
int createRaw(int protocol_to_sniff)
{
	int raw_fd = socket(AF_INET, SOCK_RAW, protocol_to_sniff);
	if (raw_fd < 0)
	{
		printf("ERROR creating raw socket\n");
		return(1);
	}else{
		printf( "Raw Socket Created!		:-D\n");
		return raw_fd;
	}
}
int bindRaw(int socketToBind,struct sockaddr_in *sin)
{
	int err = bind(socketToBind,(struct sockaddr *)sin,sizeof(*sin));
	if (err < 0)
	{
		printf("ERROR binding socket.\n");
		return(1);
	}else{
		printf("Bound socket!			:-D\n");
		return 0;
	}
}
 
int main(int argc,char* argv[])
{
	//create raw socket for binding
	int bindSocket = createRaw(6);
 
	//create structures
	struct sockaddr_in sin;
	unsigned char packetBuf[4096];
 
	//specify port to bind to
	bzero((char *)&sin,sizeof(sin));
	sin.sin_port = htons(55000);
 
	//bind socket
	bindRaw(bindSocket,&sin);
 
	//inform os of recieving raw ip packet
	{
		int tmp = 1;
		setsockopt(bindSocket, 0, IP_HDRINCL,&tmp,sizeof(tmp));
	}
 
	//re-use socket structure
	//Details about where this custom packet is going:
	bzero((char *)& sin, sizeof(sin));
	sin.sin_family = AF_INET;
	sin.sin_port = htons(55000);	//port to send packet to
	sin.sin_addr.s_addr = inet_addr("173.194.34.215");	//IP to send packet to
 
 
	unsigned short buffer_size = sizeof(struct ip) + sizeof(struct tcphdr);//+ sizeof(data);
	//cout << "Buffer size: " << buffer_size << endl;
 
	struct ip *IPheader = (struct ip *) packetBuf;
	struct tcphdr *TCPheader = (struct tcphdr *) (packetBuf + sizeof (struct ip));
 
	//Fill out IP Header information:
	IPheader->ip_hl = 5;
	IPheader->ip_v = 4;		//IPv4
	IPheader->ip_tos = 0;		//type of service
	IPheader->ip_len = htons(buffer_size);	//length
	IPheader->ip_id = htonl(54321);
	IPheader->ip_off = 0;
	IPheader->ip_ttl = 255;	//max routers to pass through
	IPheader->ip_p = 6;		//tcp
	IPheader->ip_sum = 0;	//Set to 0 before calulating later
	IPheader->ip_src.s_addr = inet_addr("11.11.11.11");	//source IP address
	IPheader->ip_dst.s_addr = inet_addr("173.194.34.215");	//destination IP address
 
	//Fill out TCP Header information:
	TCPheader->th_sport = htons(55000);	//source port
	TCPheader->th_dport = htons(55000);			//destination port
	TCPheader->th_seq = 0;
	TCPheader->th_ack = 0;	//Only 0 on initial SYN 
	TCPheader->th_off = 0;
	TCPheader->th_flags = TH_SYN;	//SYN flag set
	TCPheader->th_win = htonl(65535);	//used for segmentation
	TCPheader->th_sum = 0;				//Kernel fill this out
	TCPheader->th_urp = 0;
 
	//Now fill out the checksum for the IPheader
	IPheader->ip_sum = csum((unsigned short *) packetBuf, IPheader->ip_len >> 1);
	//cout << "IP Checksum: " << IPheader->ip_sum << endl;
	//create raw socket for sending ip packet
	int sendRaw = createRaw(6);
	if (sendRaw < 0)
	{
		printf( "ERROR creating raw socket for sending.\n");
		return(1);
	}else{
		printf( "Raw socket created for sending!	:-D\n");
	}
	int sendErr = sendto(sendRaw,packetBuf,
		sizeof(packetBuf),0,(struct sockaddr *)&sin,sizeof(sin));
 
	if (sendErr < sizeof(packetBuf))
	{
		//cout << sendErr << " out of " << sizeof(packetBuf) << " were sent.\n";
		return(1);
	}else{
		//cout << "<" << sendErr << "> Sent message!!!		:-D\n";
	}
 
	printf( "Sleeping for 2 seconds");
	sleep(1);
	printf(".");
	sleep(1);
	printf(".\n");
	char recvPacket[4096] = "";
	int newData = recv(bindSocket,recvPacket,sizeof(recvPacket),0);
	if (newData <=0)
	{
		//cout << newData << " returned by recv! :(\n";
		return(1);
	}else{
		//cout << "<" << newData << "> RECIEVE SUCCESSFULL!!	:-D\n";
	}
 
	return 0;	
}