void PerformLookup ( PCHAR pAddr )
Definition at line 233 of file nslookup.c.
{
    /* Needed to issue DNS packets and parse them. */
    PCHAR Buffer = NULL, RecBuffer = NULL;
    CHAR pResolve[256];
    CHAR pResult[256];
    ULONG BufferLength = 0, RecBufferLength = 512;
    int i = 0, j = 0, k = 0, d = 0;
    BOOL bOk = FALSE;

    /* Makes things easier when parsing the response packet. */
    UCHAR Header2;
    USHORT NumQuestions;
    USHORT NumAnswers;
    USHORT NumAuthority;
    USHORT Type;

    if( (strlen( pAddr ) + 1) > 255 ) return;

    _tprintf( _T("Server:  %s\n"), State.DefaultServer );
    _tprintf( _T("Address:  %s\n\n"), State.DefaultServerAddress );

    if( !strcmp( TypeA, State.type )
        || !strcmp( TypeAAAA, State.type )
        || !strcmp( TypeBoth, State.type ) )
    {
        Type = TYPE_A;
        if( IsValidIP( pAddr ) ) Type = TYPE_PTR;
    }
    else
        Type = TypeNametoTypeID( State.type );

    /* If it's a PTR lookup then append the ARPA sig to the end. */
    if( (Type == TYPE_PTR) && IsValidIP( pAddr ) )
    {
        ReverseIP( pAddr, pResolve );
        strcat( pResolve, ARPA_SIG );
    }
    else
    {
        strcpy( pResolve, pAddr );
    }

    /* Base header length + length of QNAME + length of QTYPE and QCLASS */
    BufferLength = 12 + (strlen( pResolve ) + 2) + 4;

    /* Allocate memory for the buffer. */
    Buffer = HeapAlloc( ProcessHeap, 0, BufferLength );
    if( !Buffer )
    {
        _tprintf( _T("ERROR: Out of memory\n") );
        goto cleanup;
    }

    /* Allocate memory for the return buffer. */
    RecBuffer = HeapAlloc( ProcessHeap, 0, RecBufferLength );
    if( !RecBuffer )
    {
        _tprintf( _T("ERROR: Out of memory\n") );
        goto cleanup;
    }

    /* Insert the ID field. */
    ((PSHORT)&Buffer[i])[0] = htons( RequestID );
    i += 2;

    /* Bits 0-7 of the second 16 are all 0, except for when recursion is
    desired. */
    Buffer[i] = 0x00;
    if( State.recurse) Buffer[i] |= 0x01;
    i += 1;

    /* Bits 8-15 of the second 16 are 0 for a query. */
    Buffer[i] = 0x00;
    i += 1;

    /* Only 1 question. */
    ((PSHORT)&Buffer[i])[0] = htons( 1 );
    i += 2;

    /* We aren't sending a response, so 0 out the rest of the header. */
    Buffer[i] = 0x00;
    Buffer[i + 1] = 0x00;
    Buffer[i + 2] = 0x00;
    Buffer[i + 3] = 0x00;
    Buffer[i + 4] = 0x00;
    Buffer[i + 5] = 0x00;
    i += 6;

    /* Walk through the query address. Split each section delimited by '.'.
       Format of the QNAME section is length|data, etc. Last one is null */
    j = i;
    i += 1;

    for( k = 0; k < strlen( pResolve ); k += 1 )
    {
        if( pResolve[k] != '.' )
        {
            Buffer[i] = pResolve[k];
            i += 1;
        }
        else
        {
            Buffer[j] = (i - j) - 1;
            j = i;
            i += 1;
        }
    }

    Buffer[j] = (i - j) - 1;
    Buffer[i] = 0x00;
    i += 1;

    /* QTYPE */
    ((PSHORT)&Buffer[i])[0] = htons( Type );
    i += 2;

    /* QCLASS */
    ((PSHORT)&Buffer[i])[0] = htons( ClassNametoClassID( State.Class ) );

    /* Ship off the request to the DNS server. */
    bOk = SendRequest( Buffer,
                       BufferLength,
                       RecBuffer,
                       &RecBufferLength );
    if( !bOk ) goto cleanup;

    /* Start parsing the received packet. */
    Header2 = RecBuffer[3];
    NumQuestions = ntohs( ((PSHORT)&RecBuffer[4])[0] );
    NumAnswers = ntohs( ((PSHORT)&RecBuffer[6])[0] );
    NumAuthority = ntohs( ((PUSHORT)&RecBuffer[8])[0] );
    Type = 0;

    /* Check the RCODE for failure. */
    d = Header2 & 0x0F;
    if( d != RCODE_NOERROR )
    {
        switch( d )
        {
        case RCODE_NXDOMAIN:
            _tprintf( _T("*** %s can't find %s: Non-existant domain\n"), State.DefaultServer, pAddr );
            break;
            
        case RCODE_REFUSED:
            _tprintf( _T("*** %s can't find %s: Query refused\n"), State.DefaultServer, pAddr );
            break;

        default:
            _tprintf( _T("*** %s can't find %s: Unknown RCODE\n"), State.DefaultServer, pAddr );
        }
            
        goto cleanup;
    }

    k = 12;

    if( NumQuestions )
    {
        /* Blow through the questions section since we don't care about it. */
        for( i = 0; i < NumQuestions; i += 1 )
        {
            k += ExtractName( RecBuffer, pResult, k, 0 );
            k += 4;
        }
    }

    if( NumAnswers )
    {
        /* Skip the name. */
        k += ExtractName( RecBuffer, pResult, k, 0 );

        Type = ntohs( ((PUSHORT)&RecBuffer[k])[0] );
        k += 8;

        d = ntohs( ((PUSHORT)&RecBuffer[k])[0] );
        k += 2;

        if( TYPE_PTR == Type )
        {
            k += ExtractName( RecBuffer, pResult, k, d );
        }
        else if( TYPE_A == Type )
        {
            k += ExtractIP( RecBuffer, pResult, k );
        }
    }

    /* FIXME: This'll need to support more than PTR and A at some point. */
    if( !strcmp( State.type, TypePTR ) )
    {
        if( TYPE_PTR == Type )
        {
            _tprintf( _T("%s     name = %s\n"), pResolve, pResult );
        }
        else
        {
        }
    }
    else if( !strcmp( State.type, TypeA )
          || !strcmp( State.type, TypeAAAA )
          || !strcmp( State.type, TypeBoth ) )
    {
        if( (TYPE_A == Type) /*|| (TYPE_AAAA == Type)*/ )
        {
            if( 0 == NumAuthority )
                _tprintf( _T("Non-authoritative answer:\n") );

            _tprintf( _T("Name:    %s\n"), pAddr );
            _tprintf( _T("Address:  %s\n\n"), pResult );
        }
        else
        {
            _tprintf( _T("Name:    %s\n"), pResult );
            _tprintf( _T("Address:  %s\n\n"), pAddr );
        }
    }

cleanup:
    /* Free memory. */
    if( Buffer ) HeapFree( ProcessHeap, 0, Buffer );
    if( RecBuffer ) HeapFree( ProcessHeap, 0, RecBuffer );

    RequestID += 1;
}
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