C++实现ping程序实例

 //2.创建并初始化ICMP封包
 char buff[sizeof(ICMP_HDR)+32] = {0};
 ICMP_HDR* pIcmp = (ICMP_HDR*)buff;
 pIcmp->icmp_type = 8;
 pIcmp->icmp_code = 0;
 pIcmp->icmp_checksum = 0;
 pIcmp->icmp_id = (USHORT)::GetCurrentProcessId();
 pIcmp->icmp_sequence = 0;
 pIcmp->icmp_timestamp = 0;
 //填充数据
 memset(&buff[sizeof(ICMP_HDR)], 'E', 32);

 //开始发送和接收封包
 USHORT nSeq = 0;
 SOCKADDR_IN dest;
 dest.sin_family = AF_INET;
 dest.sin_port = htons(0);
 dest.sin_addr.S_un.S_addr = inet_addr(szIp); //inet_addr("192.168.19.63"); //inet_addr(szIp);220.181.111.147
 CString strToShow="";
 char* pszRevBuf = new char[1024]; //[1024] = {0};
 memset(pszRevBuf, 0, 1024);
 SOCKADDR_IN from;
 int nFromLen= sizeof(from);
 while (TRUE)
 {
  //3. 调用sendto发送ICMP请求
  static int nCount=0;
  if (nCount++==4)
  {
   break;
  }
  pIcmp->icmp_checksum = checksum((USHORT*)buff, sizeof(ICMP_HDR)+32);
  pIcmp->icmp_sequence = ++nSeq;
  pIcmp->icmp_timestamp = ::GetTickCount();
  int nRet;
  nRet = ::sendto(sRaw, buff, sizeof(ICMP_HDR)+32, 0, (SOCKADDR*)&dest, sizeof(dest));
  if (nRet == SOCKET_ERROR)
  {
   int nError = ::WSAGetLastError();
   strToShow += "sendto error\r\n";
   return -1;
  }
  
  //4. 调用recvfrom接受ICMP响应
  nRet = ::recvfrom(sRaw, pszRevBuf, 1024, 0, (sockaddr*)&from, &nFromLen);
  if (nRet == SOCKET_ERROR)
  {
   if (::WSAGetLastError() == WSAETIMEDOUT)
   {
    strToShow += "timeout\r\n";
    continue;
   }
   strToShow += "recvfrom error\r\n";
   return -1;
  }
  //解析接收到的ICMP包
  int nTick = ::GetTickCount();
  if (nRet < sizeof(ICMP_HDR)+sizeof(IPHeader))
  {
   strToShow += "less byte recved..\r\n";
  }
  ICMP_HDR* pRecvIcmp = (ICMP_HDR*)(pszRevBuf + sizeof(IPHeader));// 跳过IP头
  if (pRecvIcmp->icmp_type != 0)
  {
   strToShow += "不是回显类型";
   return -1;
  }
  if (pRecvIcmp->icmp_id != ::GetCurrentProcessId())
  {
   strToShow += "不是本进程的回显包\r\n";
   return -1;
  }
  CString strTemp;
  strTemp.Format("收到来自于[%s]IP的%04d字节\r\n", inet_ntoa(from.sin_addr), nRet);
  strToShow += strTemp;

  strTemp = "";
  strTemp.Format("序列号:%d\r\n", pRecvIcmp->icmp_sequence);
  strToShow += strTemp;

  strTemp = "";
  strTemp.Format("花费时间:%d\r\n", nTick - pRecvIcmp->icmp_timestamp);
 }
 strToShow += "**********************************";
 ::SetDlgItemTextA(hWnd, IDC_DATA, strToShow);
 return 0;
}

 //如果为奇数, 将最后一个字扩展到双字，再累加
 if (nSize)
 {
  cksum += *(UCHAR*)buff;
 }
 //将cksum的高16位与低16位相加，取反后得到校验和
 cksum = (cksum>>16) + (cksum & 0xffff);
 cksum += (cksum>>16);
 return (USHORT)(~cksum);
}
BOOL SetTimeOut(SOCKET s, int nTime, BOOL bRecv)
{
 int ret = ::setsockopt(s, SOL_SOCKET, bRecv?SO_RCVTIMEO:SO_SNDTIMEO, (char*)&nTime, sizeof(nTime));
 return ret!=SOCKET_ERROR;
}
typedef struct icmp_hdr
{
 unsigned char icmp_type;
 unsigned char icmp_code;
 unsigned short icmp_checksum;
 //下面是回显头
 unsigned short icmp_id;
 unsigned short icmp_sequence;
 unsigned long icmp_timestamp;
}ICMP_HDR, *PICMP_HDR;

typedef struct _IPHeader
{
 UCHAR iphVerLen;
 UCHAR ipTOS;
 USHORT ipLength;
 USHORT ipID;
 USHORT ipFlag;
 UCHAR ipTTL;
 UCHAR ipProtocol;
 USHORT ipCheckSum;
 ULONG ipSource;
 ULONG ipDestination;
}IPHeader, *PIPHeader;