wangyu-udp2raw/network.cpp

/*
 * network.cpp
 *
 *  Created on: Jul 29, 2017
 *      Author: wangyu
 */
#include "common.h"
#include "network.h"
#include "log.h"

int raw_recv_fd=-1;
int raw_send_fd=-1;
uint32_t link_level_header_len=0;//set it to 14 if SOCK_RAW is used in socket(PF_PACKET, SOCK_RAW, htons(ETH_P_IP));

int seq_mode=2;

int filter_port=-1;

int disable_bpf_filter=0;  //for test only,most time no need to disable this

uint32_t bind_address_uint32=0;



struct sock_filter code_tcp_old[] = {
		{ 0x28, 0, 0, 0x0000000c },//0
		{ 0x15, 0, 10, 0x00000800 },//1
		{ 0x30, 0, 0, 0x00000017 },//2
		{ 0x15, 0, 8, 0x00000006 },//3
		{ 0x28, 0, 0, 0x00000014 },//4
		{ 0x45, 6, 0, 0x00001fff },//5
		{ 0xb1, 0, 0, 0x0000000e },//6
		{ 0x48, 0, 0, 0x0000000e },//7
		{ 0x15, 2, 0, 0x0000ef32 },//8
		{ 0x48, 0, 0, 0x00000010 },//9
		{ 0x15, 0, 1, 0x0000ef32 },//10
		{ 0x6, 0, 0, 0x0000ffff },//11
		{ 0x6, 0, 0, 0x00000000 },//12
};
struct sock_filter code_tcp[] = {
{ 0x5, 0, 0, 0x00000001 },//0    //jump to 2,dirty hack from tcpdump -d's output
{ 0x5, 0, 0, 0x00000000 },//1
{ 0x30, 0, 0, 0x00000009 },//2
{ 0x15, 0, 6, 0x00000006 },//3
{ 0x28, 0, 0, 0x00000006 },//4
{ 0x45, 4, 0, 0x00001fff },//5
{ 0xb1, 0, 0, 0x00000000 },//6
{ 0x48, 0, 0, 0x00000002 },//7
{ 0x15, 0, 1, 0x0000fffe },//8
{ 0x6, 0, 0, 0x0000ffff },//9
{ 0x6, 0, 0, 0x00000000 },//10
};
int code_tcp_port_index=8;

struct sock_filter code_udp[] = {
{ 0x5, 0, 0, 0x00000001 },
{ 0x5, 0, 0, 0x00000000 },
{ 0x30, 0, 0, 0x00000009 },
{ 0x15, 0, 6, 0x00000011 },
{ 0x28, 0, 0, 0x00000006 },
{ 0x45, 4, 0, 0x00001fff },
{ 0xb1, 0, 0, 0x00000000 },
{ 0x48, 0, 0, 0x00000002 },
{ 0x15, 0, 1, 0x0000fffe },
{ 0x6, 0, 0, 0x0000ffff },
{ 0x6, 0, 0, 0x00000000 },
};
int code_udp_port_index=8;
struct sock_filter code_icmp[] = {
{ 0x5, 0, 0, 0x00000001 },
{ 0x5, 0, 0, 0x00000000 },
{ 0x30, 0, 0, 0x00000009 },
{ 0x15, 0, 1, 0x00000001 },
{ 0x6, 0, 0, 0x0000ffff },
{ 0x6, 0, 0, 0x00000000 },
};

/*

tcpdump -i eth1  ip and icmp -d
(000) ldh      [12]
(001) jeq      #0x800           jt 2    jf 5
(002) ldb      [23]
(003) jeq      #0x1             jt 4    jf 5
(004) ret      #65535
(005) ret      #0

tcpdump -i eth1  ip and icmp -dd
{ 0x28, 0, 0, 0x0000000c },
{ 0x15, 0, 3, 0x00000800 },
{ 0x30, 0, 0, 0x00000017 },
{ 0x15, 0, 1, 0x00000001 },
{ 0x6, 0, 0, 0x0000ffff },
{ 0x6, 0, 0, 0x00000000 },


 */
/*
  tcpdump -i eth1 ip and tcp and dst port 65534 -dd

{ 0x28, 0, 0, 0x0000000c },
{ 0x15, 0, 8, 0x00000800 },
{ 0x30, 0, 0, 0x00000017 },
{ 0x15, 0, 6, 0x00000006 },
{ 0x28, 0, 0, 0x00000014 },
{ 0x45, 4, 0, 0x00001fff },
{ 0xb1, 0, 0, 0x0000000e },
{ 0x48, 0, 0, 0x00000010 },
{ 0x15, 0, 1, 0x0000fffe },
{ 0x6, 0, 0, 0x0000ffff },
{ 0x6, 0, 0, 0x00000000 },

 (000) ldh      [12]
(001) jeq      #0x800           jt 2    jf 10
(002) ldb      [23]
(003) jeq      #0x6             jt 4    jf 10
(004) ldh      [20]
(005) jset     #0x1fff          jt 10   jf 6
(006) ldxb     4*([14]&0xf)
(007) ldh      [x + 16]
(008) jeq      #0xfffe          jt 9    jf 10
(009) ret      #65535
(010) ret      #0

 */

packet_info_t::packet_info_t()
{
	src_port=0;
	dst_port=0;
	if (raw_mode == mode_faketcp)
	{
		protocol = IPPROTO_TCP;
		ack_seq = get_true_random_number();
		seq = get_true_random_number();
	}
	else if (raw_mode == mode_udp)
	{
		protocol = IPPROTO_UDP;
	}
	else if (raw_mode == mode_icmp)
	{
		protocol = IPPROTO_ICMP;
	}

}


int init_raw_socket()
{

	raw_send_fd = socket(AF_INET , SOCK_RAW , IPPROTO_TCP);


    if(raw_send_fd == -1) {
    	mylog(log_fatal,"Failed to create raw_send_fd\n");
        //perror("Failed to create raw_send_fd");
        exit(1);
    }

    if(setsockopt(raw_send_fd, SOL_SOCKET, SO_SNDBUFFORCE, &socket_buf_size, sizeof(socket_buf_size))<0)
    {
    	mylog(log_fatal,"SO_SNDBUFFORCE fail\n");
    	exit(1);
    }
	//raw_fd = socket(AF_PACKET, SOCK_DGRAM, htons(ETH_P_ALL));

	raw_recv_fd= socket(PF_PACKET, SOCK_DGRAM, htons(ETH_P_IP));

    if(raw_recv_fd == -1) {
    	mylog(log_fatal,"Failed to create raw_recv_fd\n");
        //perror("");
        exit(1);
    }

    if(setsockopt(raw_recv_fd, SOL_SOCKET, SO_RCVBUFFORCE, &socket_buf_size, sizeof(socket_buf_size))<0)
    {
    	mylog(log_fatal,"SO_RCVBUFFORCE fail\n");
    	exit(1);
    }

    //IP_HDRINCL to tell the kernel that headers are included in the packet

    int one = 1;
    const int *val = &one;
    if (setsockopt (raw_send_fd, IPPROTO_IP, IP_HDRINCL, val, sizeof (one)) < 0) {
    	mylog(log_fatal,"Error setting IP_HDRINCL %d\n",errno);
        //perror("Error setting IP_HDRINCL");
        exit(2);
    }

    setnonblocking(raw_send_fd); //not really necessary
    setnonblocking(raw_recv_fd);

	return 0;
}
void init_filter(int port)
{
	sock_fprog bpf;
	if(raw_mode==mode_faketcp||raw_mode==mode_udp)
	{
		filter_port=port;
	}
	if(disable_bpf_filter) return;
	//if(raw_mode==mode_icmp) return ;
	//code_tcp[8].k=code_tcp[10].k=port;
	if(raw_mode==mode_faketcp)
	{
		bpf.len = sizeof(code_tcp)/sizeof(code_tcp[0]);
		code_tcp[code_tcp_port_index].k=port;
		bpf.filter = code_tcp;
	}
	else if(raw_mode==mode_udp)
	{
		bpf.len = sizeof(code_udp)/sizeof(code_udp[0]);
		code_udp[code_udp_port_index].k=port;
		bpf.filter = code_udp;
	}
	else if(raw_mode==mode_icmp)
	{
		bpf.len = sizeof(code_icmp)/sizeof(code_icmp[0]);
		bpf.filter = code_icmp;
	}

	int dummy;

	int ret=setsockopt(raw_recv_fd, SOL_SOCKET, SO_DETACH_FILTER, &dummy, sizeof(dummy)); //in case i forgot to remove
	if (ret != 0)
	{
		mylog(log_debug,"error remove fiter\n");
		//perror("filter");
		//exit(-1);
	}
	ret = setsockopt(raw_recv_fd, SOL_SOCKET, SO_ATTACH_FILTER, &bpf, sizeof(bpf));
	if (ret != 0)
	{
		mylog(log_fatal,"error set fiter\n");
		//perror("filter");
		exit(-1);
	}
}
void remove_filter()
{
	filter_port=0;
	int dummy;
	int ret=setsockopt(raw_recv_fd, SOL_SOCKET, SO_DETACH_FILTER, &dummy, sizeof(dummy));
	if (ret != 0)
	{
		mylog(log_debug,"error remove fiter\n");
		//perror("filter");
		//exit(-1);
	}
}




int send_raw_ip(raw_info_t &raw_info,const char * payload,int payloadlen)
{
	const packet_info_t &send_info=raw_info.send_info;
	const packet_info_t &recv_info=raw_info.recv_info;
	char send_raw_ip_buf[buf_len];

	struct iphdr *iph = (struct iphdr *) send_raw_ip_buf;
    memset(iph,0,sizeof(iphdr));

	struct sockaddr_in sin;
    sin.sin_family = AF_INET;
    //sin.sin_port = htons(info.dst_port); //dont need this
    sin.sin_addr.s_addr = send_info.dst_ip;

    iph->ihl = sizeof(iphdr)/4;  //we dont use ip options,so the length is just sizeof(iphdr)
    iph->version = 4;
    iph->tos = 0;

   // iph->id = htonl (ip_id++); //Id of this packet
    // iph->id = 0; //Id of this packet  ,kernel will auto fill this if id is zero
    iph->frag_off = htons(0x4000); //DF set,others are zero
   // iph->frag_off = htons(0x0000); //DF set,others are zero
    iph->ttl = 64;
    iph->protocol = send_info.protocol;
    iph->check = 0; //Set to 0 before calculating checksum
    iph->saddr = send_info.src_ip;    //Spoof the source ip address
    iph->daddr = send_info.dst_ip;

    uint16_t ip_tot_len=sizeof (struct iphdr)+payloadlen;
   // iph->tot_len = htons(ip_tot_len);            //this is not necessary ,kernel will always auto fill this  //http://man7.org/linux/man-pages/man7/raw.7.html
    //iph->tot_len = ip_tot_len;
    memcpy(send_raw_ip_buf+sizeof(iphdr) , payload, payloadlen);

    //iph->check = csum ((unsigned short *) send_raw_ip_buf, ip_tot_len); //this is not necessary ,kernel will always auto fill this

    int ret = sendto(raw_send_fd, send_raw_ip_buf, ip_tot_len ,  0, (struct sockaddr *) &sin, sizeof (sin));

    if(ret==-1)
    {
    	mylog(log_debug,"sendto failed\n");
    	//perror("why?");
    	return -1;
    }
    return 0;
}
int peek_raw(uint32_t &ip,uint16_t &port)
{	static char peek_raw_buf[buf_len];
	char *ip_begin=peek_raw_buf+link_level_header_len;
	struct sockaddr saddr;
	socklen_t saddr_size;
	int recv_len = recvfrom(raw_recv_fd, peek_raw_buf,buf_len, MSG_PEEK ,&saddr , &saddr_size);//change buf_len to something smaller,we only need header here
	iphdr * iph = (struct iphdr *) (ip_begin);
	//mylog(log_info,"recv_len %d\n",recv_len);
	if(recv_len<int(sizeof(iphdr)))
	{
		return -1;
	}
	ip=iph->saddr;
    unsigned short iphdrlen =iph->ihl*4;
    char *payload=ip_begin+iphdrlen;

	//mylog(log_info,"protocol %d\n",iph->protocol);
    switch(raw_mode)
    {
    	case mode_faketcp:
    	{
    		if(iph->protocol!=IPPROTO_TCP) return -1;
    		struct tcphdr *tcph=(tcphdr *)payload;
    		if(recv_len<int( iphdrlen+sizeof(tcphdr) ))
    			return -1;
    		port=ntohs(tcph->source);
			break;
    	}
    	case mode_udp:
    	{
    		if(iph->protocol!=IPPROTO_UDP) return -1;
    		struct udphdr *udph=(udphdr *)payload;
    		if(recv_len<int(iphdrlen+sizeof(udphdr)))
    			return -1;
    		port=ntohs(udph->source);
			break;
    	}
    	case mode_icmp:
    	{
    		if(iph->protocol!=IPPROTO_ICMP) return -1;
    		struct icmphdr *icmph=(icmphdr *)payload;
    		if(recv_len<int( iphdrlen+sizeof(icmphdr) ))
    			return -1;
    		port=ntohs(icmph->id);
			break;
    	}
    	default:return -1;
    }
    return 0;
}
int recv_raw_ip(raw_info_t &raw_info,char * &payload,int &payloadlen)
{
	const packet_info_t &send_info=raw_info.send_info;
	packet_info_t &recv_info=raw_info.recv_info;

	static char recv_raw_ip_buf[buf_len];

	iphdr *  iph;
	struct sockaddr saddr;
	socklen_t saddr_size;
	saddr_size = sizeof(saddr);
	int flag=0;

	int recv_len = recvfrom(raw_recv_fd, recv_raw_ip_buf, buf_len, flag ,&saddr , &saddr_size);

	if(recv_len<0)
	{
		mylog(log_trace,"recv_len %d\n",recv_len);
		return -1;
	}
	if(recv_len<int(link_level_header_len))
	{
		mylog(log_trace,"length error\n");
	}

	if(link_level_header_len ==14&&(recv_raw_ip_buf[12]!=8||recv_raw_ip_buf[13]!=0))
	{
		mylog(log_trace,"not an ipv4 packet!\n");
		return -1;
	}


	char *ip_begin=recv_raw_ip_buf+link_level_header_len;  //14 is eth net header

	iph = (struct iphdr *) (ip_begin);

	recv_info.src_ip=iph->saddr;
	recv_info.dst_ip=iph->daddr;
	recv_info.protocol=iph->protocol;



	if(bind_address_uint32!=0 &&recv_info.dst_ip!=bind_address_uint32)
	{
		//printf(" bind adress doenst match, dropped\n");
		return -1;
	}


    if (!(iph->ihl > 0 && iph->ihl <=60)) {
    	mylog(log_trace,"iph ihl error\n");
        return -1;
    }

	int ip_len=ntohs(iph->tot_len);

	if(recv_len-int(link_level_header_len) <ip_len)
	{
		mylog(log_debug,"incomplete packet\n");
		return -1;
	}

    unsigned short iphdrlen =iph->ihl*4;

    uint32_t ip_chk=csum ((unsigned short *) ip_begin, iphdrlen);

    if(ip_chk!=0)
     {
    	mylog(log_debug,"ip header error %d\n",ip_chk);
     	return -1;
     }

    payload=ip_begin+iphdrlen;

    payloadlen=ip_len-iphdrlen;

    if(payloadlen<0)
    {
    	mylog(log_warn,"error payload len\n");
    	return -1;
    }

	return 0;
}


int send_raw_icmp(raw_info_t &raw_info, const char * payload, int payloadlen)
{
	packet_info_t &send_info=raw_info.send_info;
	const packet_info_t &recv_info=raw_info.recv_info;

	char send_raw_icmp_buf[buf_len];
	icmphdr *icmph=(struct icmphdr *) (send_raw_icmp_buf);
	memset(icmph,0,sizeof(icmphdr));
	if(program_mode==client_mode)
	{
		icmph->type=8;
	}
	else
	{
		icmph->type=0;
	}
	icmph->code=0;
	icmph->id=htons(send_info.src_port);


	icmph->seq=htons(send_info.icmp_seq);   /////////////modify

	memcpy(send_raw_icmp_buf+sizeof(icmphdr),payload,payloadlen);

	icmph->check_sum = csum( (unsigned short*) send_raw_icmp_buf, sizeof(icmphdr)+payloadlen);

	if(send_raw_ip(raw_info,send_raw_icmp_buf,sizeof(icmphdr)+payloadlen)!=0)
	{
		return -1;
	}

	if(program_mode==client_mode)
	{
		send_info.icmp_seq++;
	}

	return 0;
}

int send_raw_udp(raw_info_t &raw_info, const char * payload, int payloadlen)
{
	const packet_info_t &send_info=raw_info.send_info;
	const packet_info_t &recv_info=raw_info.recv_info;

	char send_raw_udp_buf[buf_len];

	udphdr *udph=(struct udphdr *) (send_raw_udp_buf
			+ sizeof(struct pseudo_header));

	memset(udph,0,sizeof(udphdr));
	struct pseudo_header *psh = (struct pseudo_header *) (send_raw_udp_buf);

	udph->source = htons(send_info.src_port);
	udph->dest = htons(send_info.dst_port);

	int udp_tot_len=payloadlen+sizeof(udphdr);

	if(udp_tot_len>65535)
	{
		mylog(log_debug,"invalid len\n");
		return -1;
	}
	mylog(log_debug,"udp_len:%d %d\n",udp_tot_len,udph->len);
	udph->len=htons(uint16_t(udp_tot_len));

	memcpy(send_raw_udp_buf+sizeof(struct pseudo_header)+sizeof(udphdr),payload,payloadlen);

	psh->source_address = send_info.src_ip;
	psh->dest_address = send_info.dst_ip;
	psh->placeholder = 0;
	psh->protocol = IPPROTO_UDP;
	psh->tcp_length = htons(uint16_t(udp_tot_len));

	int csum_size = sizeof(struct pseudo_header) +udp_tot_len  ;

	udph->check = csum( (unsigned short*) send_raw_udp_buf, csum_size);

	if(send_raw_ip(raw_info,send_raw_udp_buf+ sizeof(struct pseudo_header),udp_tot_len)!=0)
	{
		return -1;
	}
	return 0;
}

int send_raw_tcp(raw_info_t &raw_info,const char * payload, int payloadlen) {  	//TODO seq increase


	packet_info_t &send_info=raw_info.send_info;
	packet_info_t &recv_info=raw_info.recv_info;

	//mylog(log_debug,"syn %d\n",send_info.syn);

	char send_raw_tcp_buf0[buf_len];
	char *send_raw_tcp_buf=send_raw_tcp_buf0;

	struct tcphdr *tcph = (struct tcphdr *) (send_raw_tcp_buf
			+ sizeof(struct pseudo_header));


	memset(tcph,0,sizeof(tcphdr));

	struct pseudo_header *psh = (struct pseudo_header *) (send_raw_tcp_buf);

	//TCP Header
	tcph->source = htons(send_info.src_port);
	tcph->dest = htons(send_info.dst_port);

	tcph->seq = htonl(send_info.seq);
	tcph->ack_seq = htonl(send_info.ack_seq);

	tcph->fin = 0;
	tcph->syn = send_info.syn;
	tcph->rst = 0;
	tcph->psh = send_info.psh;
	tcph->ack = send_info.ack;

	if (tcph->syn == 1) {
		tcph->doff = 10;  //tcp header size
		int i = sizeof(pseudo_header)+sizeof(tcphdr);
		send_raw_tcp_buf[i++] = 0x02;  //mss
		send_raw_tcp_buf[i++] = 0x04;
		send_raw_tcp_buf[i++] = 0x05;
		send_raw_tcp_buf[i++] = (char)0xb4;

		//raw_send_buf[i++]=0x01;
		//raw_send_buf[i++]=0x01;
		send_raw_tcp_buf[i++] = 0x04; //sack ok
		send_raw_tcp_buf[i++] = 0x02; //sack ok

		send_raw_tcp_buf[i++] = 0x08;   //ts
		send_raw_tcp_buf[i++] = 0x0a;

		*(uint32_t*) (&send_raw_tcp_buf[i]) = htonl(
				(uint32_t) get_current_time());

		i += 4;

		*(uint32_t*) (&send_raw_tcp_buf[i]) = htonl(send_info.ts_ack);
		i += 4;

		send_raw_tcp_buf[i++] = 0x01;
		send_raw_tcp_buf[i++] = 0x03;
		send_raw_tcp_buf[i++] = 0x03;
		send_raw_tcp_buf[i++] = 0x05;
	} else {
		tcph->doff = 8;
		int i = sizeof(pseudo_header)+sizeof(tcphdr);

		send_raw_tcp_buf[i++] = 0x01;
		send_raw_tcp_buf[i++] = 0x01;

		send_raw_tcp_buf[i++] = 0x08;  //ts
		send_raw_tcp_buf[i++] = 0x0a;

		*(uint32_t*) (&send_raw_tcp_buf[i]) = htonl(
				(uint32_t) get_current_time());

		i += 4;

		*(uint32_t*) (&send_raw_tcp_buf[i]) = htonl(send_info.ts_ack);
		i += 4;
	}

	tcph->urg = 0;
	//tcph->window = htons((uint16_t)(1024));
	tcph->window = htons((uint16_t) (10240 + random() % 100));

	tcph->check = 0; //leave checksum 0 now, filled later by pseudo header
	tcph->urg_ptr = 0;

	char *tcp_data = send_raw_tcp_buf+sizeof(struct pseudo_header) + tcph->doff * 4;

	memcpy(tcp_data, payload, payloadlen);

	psh->source_address = send_info.src_ip;
	psh->dest_address = send_info.dst_ip;
	psh->placeholder = 0;
	psh->protocol = IPPROTO_TCP;
	psh->tcp_length = htons(tcph->doff * 4 + payloadlen);

	int csum_size = sizeof(struct pseudo_header) + tcph->doff*4 + payloadlen;

	tcph->check = csum( (unsigned short*) send_raw_tcp_buf, csum_size);

	int tcp_totlen=tcph->doff*4 + payloadlen;

	if(send_raw_ip(raw_info,send_raw_tcp_buf+ sizeof(struct pseudo_header),tcp_totlen)!=0)
	{
		return -1;
	}
	if (send_info.syn == 0 && send_info.ack == 1&& payloadlen != 0)   //only modify   send_info when the packet is not part of handshake
	{
		if (seq_mode == 0)
		{

		} else if (seq_mode == 1)
		{
			send_info.seq += payloadlen;    //////////////////modify
		} else if (seq_mode == 2)
		{
			if (random() % 5 == 3)
				send_info.seq += payloadlen; //////////////////modify
		}
	}

	return 0;
}
/*
int send_raw_tcp_deprecated(const packet_info_t &info,const char * payload,int payloadlen)
{
	static uint16_t ip_id=1;
	char raw_send_buf[buf_len];
	char raw_send_buf2[buf_len];

	//if((prog_mode==client_mode&& payloadlen!=9)  ||(prog_mode==server_mode&& payloadlen!=5 )  )
	mylog(log_trace,"send raw from to %d %d %d %d\n",info.src_ip,info.src_port,info.dst_ip,info.dst_port);

	char *data;

    memset(raw_send_buf,0,payloadlen+100);

    struct iphdr *iph = (struct iphdr *) raw_send_buf;

    //TCP header
    struct tcphdr *tcph = (struct tcphdr *) (raw_send_buf + sizeof (struct ip));

    struct sockaddr_in sin;
    struct pseudo_header psh;

    //some address resolution
    sin.sin_family = AF_INET;
    sin.sin_port = htons(info.dst_port);
    sin.sin_addr.s_addr = info.dst_ip;

    //Fill in the IP Header
    iph->ihl = 5;
    iph->version = 4;
    iph->tos = 0;

    iph->id = htonl (ip_id++); //Id of this packet
    iph->frag_off = htons(0x4000); //DF set,others are zero
    iph->ttl = 64;
    iph->protocol = IPPROTO_TCP;
    iph->check = 0; //Set to 0 before calculating checksum
    iph->saddr = info.src_ip;    //Spoof the source ip address
    iph->daddr = info.dst_ip;

    //TCP Header
    tcph->source = htons(info.src_port);
    tcph->dest = htons(info.dst_port);

    tcph->seq =htonl(info.seq);
    tcph->ack_seq = htonl(info.ack_seq);

    tcph->fin=0;
    tcph->syn=info.syn;
    tcph->rst=0;
    tcph->psh=info.psh;
    tcph->ack=info.ack;

    if(tcph->syn==1)
    {
    	tcph->doff = 10;  //tcp header size
    	int i=sizeof (struct iphdr)+20;
    	raw_send_buf[i++]=0x02;//mss
    	raw_send_buf[i++]=0x04;
    	raw_send_buf[i++]=0x05;
    	raw_send_buf[i++]=0xb4;

    	//raw_send_buf[i++]=0x01;
    	//raw_send_buf[i++]=0x01;
    	raw_send_buf[i++]=0x04; //sack ok
    	raw_send_buf[i++]=0x02; //sack ok


    	raw_send_buf[i++]=0x08;   //i=6;
    	raw_send_buf[i++]=0x0a;

    	*(uint32_t*)(& raw_send_buf[i])=htonl((uint32_t)get_current_time());

    	i+=4;

    	*(uint32_t*)(& raw_send_buf[i])=htonl(info.ts_ack);
    	i+=4;

    	raw_send_buf[i++]=0x01;
    	raw_send_buf[i++]=0x03;
    	raw_send_buf[i++]=0x03;
    	raw_send_buf[i++]=0x05;
    }
    else
    {
    	tcph->doff=8;
    	int i=sizeof (struct iphdr)+20;

    	raw_send_buf[i++]=0x01;
    	raw_send_buf[i++]=0x01;

    	raw_send_buf[i++]=0x08;   //i=0;
    	raw_send_buf[i++]=0x0a;

    	*(uint32_t*)(& raw_send_buf[i])=htonl((uint32_t)get_current_time());

    	i+=4;

    	*(uint32_t*)(& raw_send_buf[i])=htonl(info.ts_ack);
    	i+=4;


    }



    tcph->urg=0;
    //tcph->window = htons((uint16_t)(1024));
    tcph->window = htons((uint16_t)(10240+random()%100));


    tcph->check = 0; //leave checksum 0 now, filled later by pseudo header
    tcph->urg_ptr = 0;


    //Data part
    data = raw_send_buf + sizeof(struct iphdr) + tcph->doff*4;

    iph->tot_len = sizeof (struct iphdr) + tcph->doff*4 + payloadlen;

    memcpy(data , payload, payloadlen);

    psh.source_address = info.src_ip;
    psh.dest_address = sin.sin_addr.s_addr;
    psh.placeholder = 0;
    psh.protocol = IPPROTO_TCP;
    psh.tcp_length = htons(tcph->doff*4 + payloadlen );

    int psize = sizeof(struct pseudo_header) + tcph->doff*4 + payloadlen;

     memcpy(raw_send_buf2 , (char*) &psh , sizeof (struct pseudo_header));
     memcpy(raw_send_buf2 + sizeof(struct pseudo_header) , tcph , tcph->doff*4 + payloadlen);

     tcph->check = csum( (unsigned short*) raw_send_buf2, psize);

     //Ip checksum
     iph->check = csum ((unsigned short *) raw_send_buf, iph->tot_len);

     mylog(log_trace,"sent seq  ack_seq len<%u %u %d>\n",g_packet_info_send.seq,g_packet_info_send.ack_seq,payloadlen);

     int ret = sendto(raw_send_fd, raw_send_buf, iph->tot_len ,  0, (struct sockaddr *) &sin, sizeof (sin));

     if(g_packet_info_send.syn==0&&g_packet_info_send.ack==1&&payloadlen!=0)
     {
    	 if(seq_mode==0)
    	 {


    	 }
    	 else if(seq_mode==1)
    	 {
    		 g_packet_info_send.seq+=payloadlen;
    	 }
    	 else if(seq_mode==2)
    	 {
    		 if(random()% 5==3 )
    			 g_packet_info_send.seq+=payloadlen;
    	 }
     }
     mylog(log_trace,"<ret:%d>\n",ret);
	 if(ret<0)
     {
	    	mylog(log_fatal,"");
    	 perror("raw send error\n");
    	 //printf("send error\n");
     }
     return 0;
}
*/

int recv_raw_icmp(raw_info_t &raw_info, char *&payload, int &payloadlen)
{
	packet_info_t &send_info=raw_info.send_info;
	packet_info_t &recv_info=raw_info.recv_info;
	static char recv_raw_icmp_buf[buf_len];

	char * ip_payload;
	int ip_payloadlen;

	if(recv_raw_ip(raw_info,ip_payload,ip_payloadlen)!=0)
	{
		mylog(log_debug,"recv_raw_ip error\n");
		return -1;
	}
	if(recv_info.protocol!=IPPROTO_ICMP)
	{
		//printf("not udp protocol\n");
		return -1;
	}

	icmphdr *icmph=(struct icmphdr *) (ip_payload);

	if(ntohs(icmph->id)!=send_info.src_port)
	{
		return -1;
	}

	recv_info.src_port=recv_info.dst_port=ntohs(icmph->id);



	if(program_mode==client_mode)
	{
		if(icmph->type!=0)
			return -1;
	}
	else
	{
		if(icmph->type!=8)
			return -1;

	}

	if(icmph->code!=0)
		return -1;

	unsigned short check = csum( (unsigned short*) ip_payload, ip_payloadlen);

	if(check!=0)
	{
		mylog(log_debug,"icmp checksum fail %x\n",check);
		return -1;
	}
	//mylog(log_info,"program_mode=%d\n",program_mode);

	if(program_mode==server_mode)
	{
		send_info.icmp_seq=ntohs(icmph->seq);
		//mylog(log_info,"send_info.seq=%d\n",send_info.seq);
	}

	payload=ip_payload+sizeof(icmphdr);
	payloadlen=ip_payloadlen-sizeof(icmphdr);
	mylog(log_debug,"get a packet len=%d\n",payloadlen);

    return 0;
}

int recv_raw_udp(raw_info_t &raw_info, char *&payload, int &payloadlen)
{
	const packet_info_t &send_info=raw_info.send_info;
	packet_info_t &recv_info=raw_info.recv_info;
	static char recv_raw_udp_buf[buf_len];
	char * ip_payload;
	int ip_payloadlen;

	if(recv_raw_ip(raw_info,ip_payload,ip_payloadlen)!=0)
	{
		mylog(log_debug,"recv_raw_ip error\n");
		return -1;
	}
	if(recv_info.protocol!=IPPROTO_UDP)
	{
		//printf("not udp protocol\n");
		return -1;
	}
	if(ip_payloadlen<int( sizeof(udphdr) ))
	{
		mylog(log_debug,"too short to hold udpheader\n");
		return -1;
	}
	udphdr *udph=(struct udphdr*)ip_payload;

	if(ntohs(udph->len)!=ip_payloadlen)
	{

		mylog(log_debug,"udp length error %d %d \n",ntohs(udph->len),ip_payloadlen);
		return -1;
	}

    if(udph->dest!=ntohs(uint16_t(filter_port)))
    {
    	//printf("%x %x",tcph->dest,);
    	return -1;
    }

    memcpy(recv_raw_udp_buf+ sizeof(struct pseudo_header) , ip_payload , ip_payloadlen);

    struct pseudo_header *psh=(pseudo_header *)recv_raw_udp_buf ;

    psh->source_address = recv_info.src_ip;
    psh->dest_address = recv_info.dst_ip;
    psh->placeholder = 0;
    psh->protocol = IPPROTO_UDP;
    psh->tcp_length = htons(ip_payloadlen);

    int csum_len=sizeof(struct pseudo_header)+ip_payloadlen;
    uint16_t udp_chk = csum( (unsigned short*) recv_raw_udp_buf, csum_len);

    if(udp_chk!=0)
    {
    	mylog(log_debug,"udp_chk:%x\n",udp_chk);
    	mylog(log_debug,"udp header error\n");
    	return -1;

    }

    char *udp_begin=recv_raw_udp_buf+sizeof(struct pseudo_header);

    recv_info.src_port=ntohs(udph->source);
    recv_info.dst_port=ntohs(udph->dest);

    payloadlen = ip_payloadlen-sizeof(udphdr);

    payload=udp_begin+sizeof(udphdr);

    return 0;
}

int recv_raw_tcp(raw_info_t &raw_info,char * &payload,int &payloadlen)
{
	packet_info_t &send_info=raw_info.send_info;
	packet_info_t &recv_info=raw_info.recv_info;

	static char recv_raw_tcp_buf[buf_len];

	char * ip_payload;
	int ip_payloadlen;


	if(recv_raw_ip(raw_info,ip_payload,ip_payloadlen)!=0)
	{
		mylog(log_debug,"recv_raw_ip error\n");
		return -1;
	}

	if(recv_info.protocol!=IPPROTO_TCP)
	{
		//printf("not tcp protocol\n");
		return -1;
	}


	tcphdr * tcph=(struct tcphdr*)ip_payload;

    unsigned short tcphdrlen = tcph->doff*4;

    if (!(tcph->doff > 0 && tcph->doff <=60)) {
    	mylog(log_debug,"tcph error\n");
    	return 0;
    }


    if(tcph->dest!=ntohs(uint16_t(filter_port)))
    {
    	//printf("%x %x",tcph->dest,);
    	return -1;
    }

    memcpy(recv_raw_tcp_buf+ sizeof(struct pseudo_header) , ip_payload , ip_payloadlen);

    struct pseudo_header *psh=(pseudo_header *)recv_raw_tcp_buf ;

    psh->source_address = recv_info.src_ip;
    psh->dest_address = recv_info.dst_ip;
    psh->placeholder = 0;
    psh->protocol = IPPROTO_TCP;
    psh->tcp_length = htons(ip_payloadlen);

    int csum_len=sizeof(struct pseudo_header)+ip_payloadlen;
    uint16_t tcp_chk = csum( (unsigned short*) recv_raw_tcp_buf, csum_len);

    if(tcp_chk!=0)
    {
    	mylog(log_debug,"tcp_chk:%x\n",tcp_chk);
    	mylog(log_debug,"tcp header error\n");
    	return -1;

    }

    char *tcp_begin=recv_raw_tcp_buf+sizeof(struct pseudo_header);  //ip packet's data part

    char *tcp_option=recv_raw_tcp_buf+sizeof(struct pseudo_header)+sizeof(tcphdr);

    recv_info.has_ts=0;
    if(tcph->doff==10)
    {
    	if(tcp_option[6]==0x08 &&tcp_option[7]==0x0a)
    	{
    		recv_info.has_ts=1;
    		recv_info.ts=ntohl(*(uint32_t*)(&tcp_option[8]));
    		recv_info.ts_ack=ntohl(*(uint32_t*)(&tcp_option[12]));
    		//g_packet_info_send.ts_ack= ntohl(*(uint32_t*)(&tcp_option[8]));
    	}
    }
    else if(tcph->doff==8)
    {
    	if(tcp_option[3]==0x08 &&tcp_option[4]==0x0a)
    	{
    		recv_info.has_ts=1;
    		recv_info.ts=ntohl(*(uint32_t*)(&tcp_option[0]));
    		recv_info.ts_ack=ntohl(*(uint32_t*)(&tcp_option[4]));
    		//g_packet_info_send.ts_ack= ntohl(*(uint32_t*)(&tcp_option[0]));
    	}
    }
    if(tcph->rst==1)
    {
    	mylog(log_warn,"%%%%%%%%%%%%%rst==1%%%%%%%%%%%%%\n");
    }

    recv_info.ack=tcph->ack;
    recv_info.syn=tcph->syn;
    recv_info.rst=tcph->rst;
    recv_info.src_port=ntohs(tcph->source);
    recv_info.dst_port=ntohs(tcph->dest);

    recv_info.seq=ntohl(tcph->seq);
    recv_info.ack_seq=ntohl(tcph->ack_seq);
    recv_info.psh=tcph->psh;

    if(recv_info.has_ts)
    {
    	send_info.ts_ack=recv_info.ts;   //////////////////////////////////////////////modify
    }

    payloadlen = ip_payloadlen-tcphdrlen;

    payload=tcp_begin+tcphdrlen;

	if (recv_info.syn == 0 && recv_info.ack == 1&& payloadlen != 0)   //only modify   send_info when the packet is not part of handshake
	{
		send_info.ack_seq=recv_info.seq;
	}
    return 0;
}
/*
int recv_raw_tcp_deprecated(packet_info_t &info,char * &payload,int &payloadlen)
{
	static char buf[buf_len];

	char raw_recv_buf[buf_len];
	char raw_recv_buf2[buf_len];
	char raw_recv_buf3[buf_len];

	iphdr *  iph;
	tcphdr * tcph;
	int size;
	struct sockaddr saddr;
	socklen_t saddr_size;
	saddr_size = sizeof(saddr);

	mylog(log_trace,"raw!\n");

	size = recvfrom(raw_recv_fd, buf, buf_len, 0 ,&saddr , &saddr_size);

	if(buf[12]!=8||buf[13]!=0)
	{
		mylog(log_debug,"not an ipv4 packet!\n");
		return -1;
	}

	char *ip_begin=buf+14;

	iph = (struct iphdr *) (ip_begin);


    if (!(iph->ihl > 0 && iph->ihl <=60)) {
    	mylog(log_debug,"iph ihl error");
        return -1;
    }

    if (iph->protocol != IPPROTO_TCP) {
    	mylog(log_debug,"iph protocal != tcp\n");
    	return -1;
    }


	int ip_len=ntohs(iph->tot_len);

    unsigned short iphdrlen =iph->ihl*4;
    tcph=(struct tcphdr*)(ip_begin+ iphdrlen);
    unsigned short tcphdrlen = tcph->doff*4;

    if (!(tcph->doff > 0 && tcph->doff <=60)) {
    	mylog(log_debug,"tcph error");
    	return 0;
    }


    if(tcph->dest!=ntohs(uint16_t(filter_port)))
    {
    	//printf("%x %x",tcph->dest,);
    	return -1;
    }
    /////ip
    uint32_t ip_chk=csum ((unsigned short *) ip_begin, iphdrlen);

    int psize = sizeof(struct pseudo_header) + ip_len-iphdrlen;
    /////ip end


    ///tcp
    struct pseudo_header psh;

    psh.source_address = iph->saddr;
    psh.dest_address = iph->daddr;
    psh.placeholder = 0;
    psh.protocol = IPPROTO_TCP;
    psh.tcp_length = htons(ip_len-iphdrlen);

    memcpy(raw_recv_buf2 , (char*) &psh , sizeof (struct pseudo_header));
    memcpy(raw_recv_buf2 + sizeof(struct pseudo_header) , ip_begin+ iphdrlen , ip_len-iphdrlen);

    uint16_t tcp_chk = csum( (unsigned short*) raw_recv_buf2, psize);


   if(ip_chk!=0)
    {
	   mylog(log_debug,"ip header error %d\n",ip_chk);
    	return -1;
    }
    if(tcp_chk!=0)
    {
    	mylog(log_debug,"tcp_chk:%x\n",tcp_chk);
    	mylog(log_debug,"tcp header error\n");
    	return -1;

    }
    char *tcp_begin=raw_recv_buf2+sizeof(struct pseudo_header);  //ip packet's data part

    char *tcp_option=raw_recv_buf2+sizeof(struct pseudo_header)+sizeof(tcphdr);

    info.has_ts=0;

    if(tcph->doff==10)
    {
    	if(tcp_option[6]==0x08 &&tcp_option[7]==0x0a)
    	{
    		info.has_ts=1;
    		info.ts=ntohl(*(uint32_t*)(&tcp_option[8]));
    		info.ts_ack=ntohl(*(uint32_t*)(&tcp_option[12]));
    		//g_packet_info_send.ts_ack= ntohl(*(uint32_t*)(&tcp_option[8]));
    	}
    }
    else if(tcph->doff==8)
    {
    	if(tcp_option[3]==0x08 &&tcp_option[4]==0x0a)
    	{
    		info.has_ts=1;
    		info.ts=ntohl(*(uint32_t*)(&tcp_option[0]));
    		info.ts_ack=ntohl(*(uint32_t*)(&tcp_option[4]));
    		//g_packet_info_send.ts_ack= ntohl(*(uint32_t*)(&tcp_option[0]));
    	}
    }

    if(tcph->rst==1)
    {
    	mylog(log_warn,"%%%%%%%%%%rst==1%%%%%%%%%%%%%\n");
    }


    info.ack=tcph->ack;
    info.syn=tcph->syn;
    info.rst=tcph->rst;
    info.src_port=ntohs(tcph->source);
    info.src_ip=iph->saddr;
    info.seq=ntohl(tcph->seq);
    info.ack_seq=ntohl(tcph->ack_seq);
    info.psh=tcph->psh;
    if(info.has_ts)
    {
    	g_packet_info_send.ts_ack=info.ts;
    }
    ////tcp end


    payloadlen = ip_len-tcphdrlen-iphdrlen;

    payload=ip_begin+tcphdrlen+iphdrlen;

    if(payloadlen>0&&payload[0]=='h')
    {
    	mylog(log_debug,"recvd <%u %u %d>\n",ntohl(tcph->seq ),ntohl(tcph->ack_seq), payloadlen);
    }

    if(payloadlen>0&&tcph->syn==0&&tcph->ack==1)
    {
    	//if(seq_increse)
    		g_packet_info_send.ack_seq=ntohl(tcph->seq)+(uint32_t)payloadlen;
    }


    //printf("%d\n",ip_len);

    mylog(log_trace,"<%u,%u,%u,%u,%d>\n",(unsigned int)iphdrlen,(unsigned int)tcphdrlen,(unsigned int)tcph->syn,(unsigned int)tcph->ack,payloadlen);


	return 0;
}*/
int send_raw(raw_info_t &raw_info,const char * payload,int payloadlen)
{
	packet_info_t &send_info=raw_info.send_info;
	packet_info_t &recv_info=raw_info.recv_info;
	mylog(log_trace,"send_raw : from %x %d  to %x %d\n",send_info.src_ip,send_info.src_port,send_info.dst_ip,send_info.dst_port);
	switch(raw_mode)
	{
		case mode_faketcp:return send_raw_tcp(raw_info,payload,payloadlen);
		case mode_udp: return send_raw_udp(raw_info,payload,payloadlen);
		case mode_icmp: return send_raw_icmp(raw_info,payload,payloadlen);
		default:return -1;
	}

}
int recv_raw(raw_info_t &raw_info,char * &payload,int &payloadlen)
{
	packet_info_t &send_info=raw_info.send_info;
	packet_info_t &recv_info=raw_info.recv_info;
	switch(raw_mode)
	{
		case mode_faketcp:return recv_raw_tcp(raw_info,payload,payloadlen);
		case mode_udp: return recv_raw_udp(raw_info,payload,payloadlen);
		case mode_icmp: return recv_raw_icmp(raw_info,payload,payloadlen);
		default:	return -1;
	}

}