Ping命令的實現)

PING (Packet InterNet Groper) 是一個非常有用的命令,它可以用來測試兩個主機之間的連通性.PING使用了ICMP回送請求與回送回答報文.PING是應用程式層直接使用網路層ICMP的一個例子.它沒有通過運輸層的TCP或UDP.

     在Windows平台編程實現PING的最簡單方法是調用Iphlpapi.dll這個動態連結程式庫，引用以下幾個函數:

     1. IcmpCreateFile(); // opens a handle on which IPv4 ICMP echo requests can be issued.

     2. IcmpSendEcho(); // sends an IPv4 ICMP echo request and returns any echo response replies.

                                  // The call returns when the time-out has expired or the reply buffer is filled.

     3. IcmpCloseHandle(); // closes a handle opened by a call to the IcmpCreateFile or Icmp6CreateFile functions.

以下是實現代碼：

 

 //    Ping.c // //    利用ICMP回送請求與回答報文類比Ping命令 // //    Step: //    1. Open ICMP handle //    2. Sends an IPv4 ICMP echo request and returns any echo response replies. //    3. Display the infomation for response echo. //    4. Close ICMP handle // //    Configuration before Build Solution: //    Project->Properties->Linker->Input->Addtional Dependencies : Iphlpapi.lib Ws2_32.lib  #include <winsock2.h> #include <iphlpapi.h> #include <icmpapi.h> #include <stdio.h>  int main( int argc, char ** argv ) {     /* 聲明並初始設定變數 */     HANDLE hIcmp = INVALID_HANDLE_VALUE;     unsigned long ulDestIpAddr = INADDR_NONE;     char sendBuffer [] = "Send Buffer";     LPVOID lpReplyBuffer = NULL;     int iReplySize = 0;     DWORD dwTimeout = 1000;     DWORD dwRetVal = 0;      /* 開啟ICMP控制代碼    */     hIcmp = IcmpCreateFile ();     if ( INVALID_HANDLE_VALUE == hIcmp )     {         printf ( "Open ICMP failure!\n" );         return EXIT_FAILURE;     }      /* 驗證命令列參數 */     if ( argc != 2 )     {         printf ( "Usage : %s IP Address\n", argv[0] );         IcmpCloseHandle( hIcmp );         return EXIT_FAILURE;     }      ulDestIpAddr = inet_addr ( argv[1] );     if ( *argv[1] == INADDR_NONE )     {         printf ( "Usage : %s IP Address\n", argv[0] );         IcmpCloseHandle( hIcmp );         return EXIT_FAILURE;     }      iReplySize = sizeof ( ICMP_ECHO_REPLY ) + sizeof ( sendBuffer );     lpReplyBuffer = malloc ( iReplySize );      /* 發送ICMP報文並等待回送請求 */     dwRetVal = IcmpSendEcho ( hIcmp, ulDestIpAddr, sendBuffer, sizeof(sendBuffer),         NULL, lpReplyBuffer, iReplySize, dwTimeout );     if ( 0 != dwRetVal )     {         // 利用一指標擷取 Request Echo 的 ICMP_ECHO_REPLY 結構執行個體         PICMP_ECHO_REPLY pReplyEcho = (PICMP_ECHO_REPLY) lpReplyBuffer;          in_addr replyIpAddr;         replyIpAddr.S_un.S_addr = pReplyEcho->Address;         printf ( "Reply from : %s\n", inet_ntoa(replyIpAddr) );          if ( dwRetVal > 1 )         {             printf ( "Retrieved %d ICMP response message.\n", dwRetVal );             printf ( "----The infomation for the first message.----\n" );         }        else         {             printf ( "Retrieved %d ICMP reponse message.\n", dwRetVal );             printf ( "----The information for the message.----\n" );         }                  printf ( "The status : %ld\n", pReplyEcho->Status );         printf ( "The reply data : %s\n", pReplyEcho->Data );         printf ( "The Roundtrip time : %ld milliseconds.\n", pReplyEcho->RoundTripTime );     }     else     {         printf ( "ICMP send failure.\n" );         printf ( "The IcmpSendEcho call error : %ld\n", GetLastError() );         IcmpCloseHandle( hIcmp );         return EXIT_FAILURE;     }       /* 關閉ICMP控制代碼 */     IcmpCloseHandle( hIcmp );      return EXIT_SUCCESS; }