ip tcp options使用

#include <sys/socket.h>
#include <arpa/inet.h>
#include <netinet/in.h>
#include <netinet/ip.h>
#include <netinet/tcp.h>
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <stdio.h>
#include <netdb.h>
#include <string.h>

#define DESTPORT 80
#define LOCALPORT 1716

#define SIP "192.168.198.129"

#if 0
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);
}
#endif

/******* send tcp *********/
void send_tcp(int sockfd,struct sockaddr_in *addr)
{
 char options[] = {0x02,0x04,0x05,0xb4,0x01,0x01,0x04,0x02};
     
 char buffer[100]; /**** save the data to send ****/
 struct ip *ip;
 struct tcphdr *tcp;
 int head_len;

 head_len=sizeof(struct ip)+sizeof(struct tcphdr)+8;

 bzero(buffer,100);

 /******** iphdr ******/
 ip=(struct ip *)buffer;
 ip->ip_v=IPVERSION;
 ip->ip_hl=sizeof(struct ip)>>2;
 ip->ip_tos=0;
 ip->ip_len=htons(head_len); /** IP data len**/
 ip->ip_id=0;
 ip->ip_off=0;
 ip->ip_ttl=MAXTTL;
 ip->ip_p=IPPROTO_TCP;
 ip->ip_sum=0;
 ip->ip_dst=addr->sin_addr;

 /******* tcp packet *****/
 tcp=(struct tcphdr *)(buffer +sizeof(struct ip));
 tcp->source=htons(LOCALPORT);
 tcp->dest=addr->sin_port; /** desctination port **/
 tcp->seq=0;
 tcp->ack_seq=0;
 tcp->doff=7;
 tcp->syn=1;
 tcp->window=htons(16384);
 tcp->check=0;

 /*options*/
 memcpy(buffer+sizeof(struct ip)+sizeof(struct tcphdr),options,8);
 
  ip->ip_src.s_addr=inet_addr(SIP);

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

  tcp->check=0;
  sendto(sockfd,buffer,head_len,0,(const struct sockaddr*)addr,sizeof(struct sockaddr_in));
}

int main(int argc,char **argv)
{
 int sockfd;
 struct sockaddr_in addr;
 struct hostent *host;
 int on=1;

 if(argc!=2)
 {
  fprintf(stderr,"Usage:%s hostname\n\a",argv[0]);
  exit(1);
 }

 bzero(&addr,sizeof(struct sockaddr_in));
 addr.sin_family=AF_INET;
 addr.sin_port=htons(DESTPORT);


 if(inet_aton(argv[1],&addr.sin_addr)==0)
 {
  host=gethostbyname(argv[1]);
  if(host==NULL)
  {
   fprintf(stderr,"HostName Error:%s\n\a",hstrerror(h_errno));
    exit(1);
  }
  addr.sin_addr=*(struct in_addr *)(host->h_addr_list[0]);
 }

 sockfd=socket(AF_INET,SOCK_RAW,IPPROTO_TCP);
 if(sockfd<0)
 {
  fprintf(stderr,"Socket Error:%s\n\a",strerror(errno));
  exit(1);
 }

 setsockopt(sockfd,IPPROTO_IP,IP_HDRINCL,&on,sizeof(on));
 setuid(getpid());

 send_tcp(sockfd,&addr);
 
 return 0;
}