winsockdnsclient.cpp

This zip file contain tow TDI client samples.

     pPort = pArgv[3];                                // Get port.
     if (0==strcmp(pPort, "."))                       // Dot given?
       pPort = dfltPort;                              // Point to default port.
    }
  else
    pPort = dfltPort;                                 // Get port.

  port = atoi(pPort);                                 // Convert ascii to integer.

  printf("   Using IP address = %s, port = %d\n", pIPAddr, port);

  // Initialize Winsocket. 
  if (0!=WSAStartup(MAKEWORD(2, 0), &WSAData))        // Accept up to Winsock 2.0.
  {
    printf(JAProgNm ":  WSAStartup failed.  Error = %d\n", WSAGetLastError());
    return 1;
  }

  // Create a UDP/IP socket that is bound to the server.
  if (INVALID_SOCKET==(ServerSock = socket(AF_INET, SOCK_DGRAM, 0)))
  {
    printf(JAProgNm ":  Allocating socket failed.  Error = %d\n", WSAGetLastError());
    return 1;
  }

  // Fill out the server socket's address information.
  destination_sin.sin_family = AF_INET;

  // Retrieve the host information corresponding to the host name.
  if (NULL==(pHostEnt = gethostbyname(pIPAddr))) 
  {
    printf(JAProgNm ":  Unable to get the host name.  Error = %d\n", WSAGetLastError ());
    closesocket (ServerSock);
    return 1;
  }

  // Assign the socket IP address.
  memcpy((char FAR *)&(destination_sin.sin_addr), 
         pHostEnt->h_addr, 
         pHostEnt->h_length
        );

  // Convert to network ordering.
  destination_sin.sin_port = htons(port);

  // Establish a connection to the server socket.
  if (SOCKET_ERROR==connect(ServerSock, 
                            (PSOCKADDR)&destination_sin, 
                            sizeof(destination_sin)
                           )
     )
  {
    ULONG error = WSAGetLastError();
    printf(JAProgNm ":  Connecting to the server failed.  Error = %d%s\n", error, WSAECONNREFUSED==error ? " (connection refused)" : "");
    closesocket(ServerSock);
    return 1;
  }

  // Send data to the server.

  #define UDPBfrSz 128

  sendLn = UDPBfrSz;

  pBuffer = (char *)malloc(sendLn);                   // Get a buffer.

  if (NULL==pBuffer)                                  // No good?
    {
     printf(JAProgNm ":  Couldn't allocate buffer, quitting\n");
     goto CloseSocket;
    }

  pQryData = (pMyDNSQuery)pBuffer;                    // Point to query.

  memset(pQryData, 0, UDPBfrSz);                      // Zero area.

  pQryData->QueryId = GetNetwkPort(2);                // Set query id (nominal).

  pQryData->RecursDesired = TRUE;                     // Show recursion OK.

  pQryData->QuestionCount = GetNetwkPort(1);          // Set number of queries.

  pQuestData = ((char *)pQryData) +                   // Point to question area.
               FIELD_OFFSET(myDNSQuery, Question);

  *(PUCHAR)pQuestData = 3;                            // Set length of first piece.

  memcpy(pQuestData+1, "www", strlen("www"));
                                                      
  *(PUCHAR)(pQuestData+4) = 3;                        // Set length of second piece.

  memcpy(pQuestData+5, "ibm", strlen("ibm"));

  *(PUCHAR)(pQuestData+8) = 3;                        // Set length of third piece.

  memcpy(pQuestData+9, "com", strlen("com"));

  pShort = (PUSHORT)((PUCHAR)pQuestData + 13);        // Point past question area.

  *pShort = GetNetwkPort(1);                          // Set QNAME.
   
  *(pShort+1) = GetNetwkPort(1);                      // Set QTYPE.
   
  sendLn = FIELD_OFFSET(myDNSQuery, Question) +       // Get total length.
           strlen(pQuestData) + 1             +
           2                                  +
           2;

  printf(JAProgNm ":  Sending %d bytes\n", sendLn);

  lclStatus = send(ServerSock,                        // Send datagram.
                   pBuffer,
                   sendLn,
                   0
                  );

  if (SOCKET_ERROR==lclStatus)
    {
     printf(JAProgNm ":  Sending data to the server failed.  Error = %d\n", WSAGetLastError());
     goto CloseSocket;
    }

  pRspData = (pMyDNSQuery)szClientA;                  // Point to response area.

  // Receive data from the server socket.
  rcRecv = recv(ServerSock, (char *)pRspData, sizeof(szClientA), 0);

  // Check if there is any data received. If there is, display it.
  if (SOCKET_ERROR==rcRecv)
  {
    printf(JAProgNm ":  No data is received, recv failed.  Error = %d\n", WSAGetLastError());
  }
  else if (0==rcRecv)
  {
    printf(JAProgNm ":  Finished receiving data\n");
  }
  else
  {
    printf("\n\n" JAProgNm ":  Total received from server = %d\n", rcRecv);

    UCHAR FullName[64];

    USHORT NameOffset =                               // Get name offset, including 2 high-order bits.
             GetNetwkPort(* (PUSHORT) (((PUCHAR)pRspData)+sendLn) );

    NameOffset &= ~0xc000;                            // Turn off high-order 2 bits.

    PUCHAR pNameFd =                                  // Point to name.
             ((PUCHAR)pQryData) + FIELD_OFFSET(myDNSQuery, QueryId) + NameOffset,
           pPartName;

    pRRData =                                         // Point to RR field.
      (pMyDNSRR)(((PUCHAR)pRspData) + sendLn + 2);

    USHORT nbrAnswers =                               // Get number of RR fields.
             GetNetwkPort(pRspData->AnswerCount);

    for (                                             // Go through RR fields.
         ULONG i = 0;
         i < nbrAnswers;
         i ++
        )
      {
       FullName[0] = 0;

       pPartName = pNameFd;

       do
         {
          pPartName =                                 // Build name, piece by piece.
            CopyNextStanza(pPartName, FullName);
         }
           while(NULL!=pPartName);

       FullName[strlen((const char *)FullName)-1] = 0;// Replace final '.' with null terminator.

       char IPAddr[16],
            Octet1[4],
            Octet2[4],
            Octet3[4],
            Octet4[4];

       ULONG addr =                                   // Get IP address, converting it from network form.
               GetNetwkAddrDw(*(PULONG)pRRData->RRData);

       _ultoa(addr>>24,              Octet1, 10);       
       _ultoa((0x00ff0000&addr)>>16, Octet2, 10);
       _ultoa((0x0000ff00&addr)>>8,  Octet3, 10);
       _ultoa(0x000000ff&addr,       Octet4, 10);

       strcpy(IPAddr, Octet1);
       strcat(IPAddr, ".");
       strcat(IPAddr, Octet2);
       strcat(IPAddr, ".");
       strcat(IPAddr, Octet3);
       strcat(IPAddr, ".");
       strcat(IPAddr, Octet4);

       printf("Name = %s, IP addr = %s\n", FullName, IPAddr);

       pRRData =                                      // Point to next RR field.
         (pMyDNSRR) ( ((PUCHAR)pRRData) + FIELD_OFFSET(myDNSRR, RRData) +
                      4 +
                      2
                    );
      }

  }

CloseSocket:
  // Close the socket.
  closesocket(ServerSock);

  WSACleanup();

  if (NULL!=pBuffer)
    free(pBuffer);                                    // Free buffer.

ExitPoint:
  return 0;
}