原始套接字透析之实现Ping

　　为了在Visual C++中更加方便地使用发送和接收ICMP报文，我们可以使用由Jay Wheeler编写的CIcmp（An ICMP Class For MFC）类，在著名的开发网站的如下地址可以下载。

　　这个类的简要框架如下：

class CIcmp: public CSocket { 　// Attributes 　public: 　　BOOL OpenNewSocket(HWND hWnd, unsigned int NotificationMessage, long NotifyEvents); 　　BOOL OpenNewSocket(HWND hWnd, unsigned int NotificationMessage, long NotifyEvents, int AFamily, int AType, int AProtocol); 　　int CloseIcmpSocket(void); 　　BOOL Connect(int ReceiveTimeout, int SendTimeout); 　　BOOL Connect(LPINT ReceiveTimeout, LPINT SendTimeout, int AFamily, int AType, int AProtocol); 　　int SetTTL(int TTL); 　　int SetAsynchNotification(HWND hWnd, unsigned int Message, long Events); 　　int Receive(LPSTR pIcmpBuffer, int IcmpBufferSize); 　　unsigned long GetIPAddress(LPSTR iHostName); 　　int Ping(LPSTR pIcmpBuffer, int IcmpBufferSize); 　　unsigned short IcmpChecksum(unsigned short FAR *lpBuf, int Len); 　　void DisplayError(CString ErrorType, CString FunctionName); 　　// Operations 　public: 　　CIcmp(void); 　　CIcmp(CIcmp &copy); 　　~CIcmp(void); 　public: 　　// I/O Buffer Pointers 　　LPIcmpHeader pIcmpHeader; 　　LPIpHeader pIpHeader; 　　SOCKET icmpSocket; 　　SOCKADDR_IN icmpSockAddr; 　　SOCKADDR_IN rcvSockAddr; 　　DWORD icmpRoundTripTime; 　　DWORD icmpPingSentAt; 　　DWORD icmpPingReceivedAt; 　　int icmpRcvLen; 　　int icmpHops; 　　int icmpMaxHops; 　　int icmpCurSeq; 　　int icmpCurId; 　　int icmpPingTimer; 　　int icmpSocketError; 　　int icmpSocketErrorMod; 　　unsigned long icmpHostAddress; 　protected: };

　　初始化网络连接的函数：

BOOL CIcmp::Connect(LPINT ReceiveTimeout, LPINT SendTimeout, int AFamily, int AType, int AProtocol) { 　int Result; 　icmpSocket = NULL; 　icmpSocket = socket(AFamily, AType, AProtocol); 　if (icmpSocket == INVALID_SOCKET) 　{ 　　icmpSocketError = WSAGetLastError(); 　　icmpSocketErrorMod = 1; 　　return FALSE; 　} 　// 　// Set receive timeout 　// 　Result = setsockopt(icmpSocket, SOL_SOCKET, SO_RCVTIMEO, (char*)ReceiveTimeout, sizeof(int)); 　if (Result == SOCKET_ERROR) 　{ 　　icmpSocketError = WSAGetLastError(); 　　icmpSocketErrorMod = 2; 　　closesocket(icmpSocket); 　　icmpSocket = INVALID_SOCKET; 　　return FALSE; 　} 　// 　// Set send timeout 　// 　Result = setsockopt(icmpSocket, SOL_SOCKET, SO_SNDTIMEO, (char*)SendTimeout,sizeof(int)); 　if (Result == SOCKET_ERROR) 　{ 　　icmpSocketError = WSAGetLastError(); 　　icmpSocketErrorMod = 3; 　　closesocket(icmpSocket); 　　icmpSocket = INVALID_SOCKET; 　　return FALSE; 　} 　icmpCurSeq = 0; 　icmpCurId = (USHORT)GetCurrentProcessId(); 　icmpHops = 0; 　return TRUE; }

　　接收的函数：

int CIcmp::Receive(LPSTR pIcmpBuffer, int IcmpBufferSize) { LPSOCKADDR pRcvSockAddr = (LPSOCKADDR)&rcvSockAddr; int Result; int RcvIpHdrLen; icmpPingReceivedAt = GetTickCount(); icmpCurId = 0; rcvSockAddr.sin_family = AF_INET; rcvSockAddr.sin_addr.s_addr = INADDR_ANY; rcvSockAddr.sin_port = 0; RcvIpHdrLen = sizeof rcvSockAddr; Result = recvfrom (icmpSocket, pIcmpBuffer, IcmpBufferSize, 0, pRcvSockAddr, &RcvIpHdrLen); if (Result == SOCKET_ERROR) { icmpSocketError = WSAGetLastError(); icmpSocketErrorMod = 1; DisplayError ("Receive","CIcmp::Receive"); return Result; } icmpRcvLen = Result; pIpHeader = (LPIpHeader)pIcmpBuffer; RcvIpHdrLen = pIpHeader->HeaderLength * 4; if (Result < RcvIpHdrLen + ICMP_MIN) { // // Too few bytes received // MessageBox(NULL, "Short message!", "CIcmp::Receive", MB_OK|MB_SYSTEMMODAL); icmpSocketErrorMod = 2; return Result; } pIcmpHeader = (LPIcmpHeader)(pIcmpBuffer + RcvIpHdrLen); icmpCurId = pIcmpHeader->IcmpId; icmpRoundTripTime = icmpPingReceivedAt - pIcmpHeader->IcmpTimestamp; if (pIcmpHeader->IcmpType != ICMP_ECHOREPLY) { // // Not an echo response! // return Result; } icmpCurSeq = pIcmpHeader->IcmpSeq; return Result; }

　　异步通知主窗口：

int CIcmp::SetAsynchNotification(HWND hWnd, unsigned int Message, long Events) { 　int Result = WSAAsyncSelect (icmpSocket,hWnd, Message, Events); 　if (Result == SOCKET_ERROR) 　{ 　　icmpSocketError = WSAGetLastError(); 　　icmpSocketErrorMod = 1; 　　icmpSocket = INVALID_SOCKET; 　} 　return Result; }

　　设置TTL：

int CIcmp::SetTTL(int TTL) { 　int Result; 　Result = setsockopt (icmpSocket, IPPROTO_IP, IP_TTL, (LPSTR)&TTL, sizeof(int)); 　if (Result == SOCKET_ERROR) 　{ 　　icmpSocketErrorMod = 1; 　　icmpSocketError = WSAGetLastError(); 　} 　return Result; }

　　Ping命令的函数：

int CIcmp::Ping (LPSTR pIcmpBuffer, int DataLen) { 　int Result; 　int IcmpBufferSize = DataLen + IcmpHeaderLength; 　pIcmpHeader = (LPIcmpHeader)pIcmpBuffer; 　memset (pIcmpBuffer, 'E', IcmpBufferSize); 　memset (pIcmpHeader, 0, IcmpHeaderLength); 　pIcmpHeader->IcmpType = ICMP_ECHO; 　pIcmpHeader->IcmpCode = 0; 　pIcmpHeader->IcmpChecksum = 0; 　pIcmpHeader->IcmpId = icmpCurId; 　pIcmpHeader->IcmpSeq = icmpCurSeq; 　pIcmpHeader->IcmpTimestamp = GetCurrentTime(); 　pIcmpHeader->IcmpChecksum = IcmpChecksum ((USHORT FAR *)pIcmpBuffer,IcmpBufferSize); 　icmpPingSentAt = GetCurrentTime(); 　Result = sendto (icmpSocket, pIcmpBuffer, IcmpBufferSize, 0, (LPSOCKADDR)&icmpSockAddr, sizeof icmpSockAddr); 　if (Result == SOCKET_ERROR) 　{ 　　icmpSocketError = WSAGetLastError(); 　　icmpSocketErrorMod = 1; 　} 　return Result; }