发出SYN包，收不到回复

Tom199818 2015-11-20 10:39:49

#include <stdio.h>



#include <stdlib.h>



#include <string.h>



#include <unistd.h>



#include <errno.h>



#include <sys/socket.h>



#include <sys/ioctl.h>



#include <sys/types.h>



#include <netinet/in.h>



#include <netinet/ip.h>



#include <netinet/if_ether.h>



#include <net/if_arp.h>



#include <netpacket/packet.h>



#include <net/if.h>



#include <net/ethernet.h>



#include <linux/tcp.h>



#define BUFLEN 54



//CRC校验和的计算



unsigned short check_sum(unsigned short *addr,int len){



        register int nleft=len;



        register int sum=0;



        register short *w=addr;



        short answer=0;







        while(nleft>1)



        {



                sum+=*w++;



                nleft-=2;



        }



        if(nleft==1)



        {



                *(unsigned char *)(&answer)=*(unsigned char *)w;



                sum+=answer;



        }







        sum=(sum>>16)+(sum&0xffff);



        sum+=(sum>>16);



        answer=~sum;



        return(answer);



}



int main(int argc,char** argv)

{



    int skfd,n;



    char buf[BUFLEN]={0};



    struct ether_header *eth;



    struct sockaddr_ll toaddr;



    struct in_addr targetIP,srcIP;

	

		 struct ip *ip;



    struct tcphdr *tcp;



    struct ifreq ifr;







    unsigned char src_mac[ETH_ALEN]={0};



    unsigned char dst_mac[ETH_ALEN]={0}; 



		unsigned char src_ip[15]={0};



		unsigned char dst_ip[15]={0};



		unsigned srcport, dstport;

	

		printf("源MAC:");

		scanf("%x:%x:%x:%x:%x:%x",

		      &src_mac[0],&src_mac[1],&src_mac[2],

		      &src_mac[3],&src_mac[4],&src_mac[5]);

	

		printf("目标MAC:");

		scanf("%x:%x:%x:%x:%x:%x",

		      &dst_mac[0],&dst_mac[1],&dst_mac[2],

		      &dst_mac[3],&dst_mac[4],&dst_mac[5]);

	

		printf("源IP:");

		scanf("%s",&src_ip);



		printf("目标IP:");

		scanf("%s", &dst_ip);

	

	  printf("目标端口:");

		scanf("%d", &dstport);

	

		printf("源端口:");

		scanf("%d", &srcport);



	

    if((skfd=socket(PF_PACKET,SOCK_RAW,htons(ETH_P_ALL)))<0)

			{



         perror("Create Error");



         exit(1);



			}







    bzero(&toaddr,sizeof(toaddr));



    bzero(&ifr,sizeof(ifr));



    strcpy(ifr.ifr_name,argv[1]);





	



    //获取接口索引



    if(-1 == ioctl(skfd,SIOCGIFINDEX,&ifr)){



           perror("get dev index error:");



           exit(1);



    }



    toaddr.sll_ifindex = ifr.ifr_ifindex;



    printf("interface Index:%d\n",ifr.ifr_ifindex);







    //开始填充，构造以太头部



    eth=(struct ether_header*)buf;



    memcpy(eth->ether_dhost,dst_mac,ETH_ALEN); 



    memcpy(eth->ether_shost,src_mac,ETH_ALEN);



    eth->ether_type = htons(ETHERTYPE_IP);



	

//开始填充IP首部



     ip=(struct ip*)(buf+sizeof(struct ether_header));







     ip->ip_v = IPVERSION;



     ip->ip_hl = sizeof(struct ip)>>2;



     ip->ip_tos = 0;



      ip->ip_len = htons(sizeof(struct ip)+sizeof(struct tcphdr));



      ip->ip_id=0;



      ip->ip_off=0;



      ip->ip_ttl=MAXTTL;



      ip->ip_p=IPPROTO_TCP;



    //  ip->ip_sum=check_sum((unsigned short*)ip,sizeof(struct ip));

	

			ip->ip_sum = 0;

			

			inet_pton(AF_INET,dst_ip,&targetIP);



			ip->ip_dst = targetIP;



			inet_pton(AF_INET,src_ip,&srcIP);

	

			ip->ip_src = srcIP;

			

        //开始填充TCP首部



      tcp = (struct tcphdr*)(buf+sizeof(struct ip)+sizeof(struct ether_header));

	

      tcp->source = htons(srcport);

	

     tcp->dest = htons(dstport);



     tcp->seq = 0;



			tcp->ack = 0;

	

			tcp->window = htons(8192);



     tcp->doff = 5;



     tcp->syn = 1;



			tcp->check = 0;

	

			toaddr.sll_family = PF_PACKET;

		   

 			tcp->check=check_sum((unsigned short*)tcp,sizeof(struct tcphdr));

			ip->ip_sum=check_sum((unsigned short*)ip,sizeof(struct ip));



			



			n=sendto(skfd,buf,BUFLEN,0,(struct sockaddr*)&toaddr,sizeof(toaddr));





    close(skfd);



    return 0;



}