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标题:为什么recvfrom()收不到数据?
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jokkkkk
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注 册:2008-10-30
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为什么recvfrom()收不到数据?
int main(int argc, char* argv[])
{  
    sockaddr_in dest,local;
   int timeout=5000;
   char d_addr[]="127.0.0.1";
   WSADATA wsaData;
   int net=WSAStartup(MAKEWORD(2,2),&wsaData);
   if (net!=0)
       return 0;
   SOCKET s_icmp=socket(AF_INET,SOCK_RAW,IPPROTO_ICMP);
   if(s_icmp==INVALID_SOCKET)
       printf("origi socket error\n");
      

   setsockopt(s_icmp,SOL_SOCKET,SO_RCVTIMEO,(char *)&timeout,sizeof(timeout));
    unsigned long cmd=0;
   ioctlsocket(s_icmp,FIONBIO,&cmd);

   local.sin_family=AF_INET;
   local.sin_port=htons(0);
   local.sin_addr.s_addr=INADDR_ANY;
  //FILL UP THE RECEIVE ADDRESS STRUCT
   if(bind(s_icmp,(sockaddr*)&local,sizeof(local))!=0)
   {
      printf("%d",::GetLastError());
       return 0;
   }
   char buf[sizeof(ICMP_HDR)+32];//32为数据部分,icmp头+数据部分

   memset(buf,'a',sizeof(ICMP_HDR)+32);
   ICMP_HDR *picmp=(ICMP_HDR*)buf;
   //将一个icmp头结构的指针,指向buf
   
   dest.sin_family=AF_INET;
   dest.sin_port=htons(0);
   dest.sin_addr.s_addr=inet_addr(d_addr);
   //fill up the destation address struct


   picmp->icmp_type=8;
   picmp->icmp_code =0;
   picmp->icmp_id=(USHORT)::GetCurrentProcessId();
   picmp->checksum=0;
   picmp->icmp_seq=0;
   //INITIALIZE the protocol header

   int cou=0;
   char     recvbuf[512];
   sockaddr_in from;
   int fromlen=sizeof(from);
   while(cou<4)
   {
       picmp->checksum=0;
       
        picmp->icmp_timestamp=(USHORT)::GetTickCount();
        picmp->icmp_seq=cou;
         picmp->checksum=checksum((USHORT*)    buf,sizeof(ICMP_HDR)+32);
        //FILL UP THE PACKET THAT STANDBY
     int size=sendto(s_icmp,buf,sizeof(ICMP_HDR)+32,0,(sockaddr*)&dest,sizeof(dest));
     //send icmp packet to dest


       if(size==SOCKET_ERROR)
       {
           printf("sendto() failed\n");
        
           return 0;
       };

      
      int rsize=recvfrom(s_icmp,recvbuf,512,0,(sockaddr*)&from,&fromlen);
    
     //receive packet from the dest
       if(rsize==SOCKET_ERROR)
       {
          
           printf("recvfrom() failed  %d \n",::WSAGetLastError());
           getchar();
       }
       if (size<sizeof(ICMP_HDR)+20)
           printf("the packet too small\n");

       ICMP_HDR *p=(ICMP_HDR*)recvbuf+20;
       //pointer *p point to received packet and IP header


       if(p->icmp_type!=0)
       {
           printf("noneecho packet\n");
           return 0;
       }
       if(p->icmp_id!=GetCurrentProcessId())
       {
           printf("other process's packet\n");
            return 0;
       }


       printf("%d bytes form %s ,",size,inet_ntoa(from.sin_addr));
       printf("sequence: %d ,%d ms\n",4-cou,p->icmp_timestamp);
       ::Sleep(1000);
       cou++;
   }
   getchar();
   closesocket(s_icmp);
   //closesocket(s);
   WSACleanup();

   return 0;
}
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2008-10-30 18:21
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