Package org.acplt.oncrpc

Class XdrHttpDecodingStream

java.lang.Object
org.acplt.oncrpc.XdrDecodingStream
org.acplt.oncrpc.XdrHttpDecodingStream
public class XdrHttpDecodingStream extends XdrDecodingStream
The XdrHttpDecodingStream class provides the necessary functionality to XdrDecodingStream to receive XDR data through HTTP tunnels.

Please note that there is currently no standard about how to tunnel XDR data over HTTP connections. There are a (quite a) few solutions out there, but they are more or less incompatible due to the lack of a RFC.

This class is responsible solely for receiving ONC/RPC replies. The reply data is base64 encoded and embedded within an ordinary plain ASCII page, as is shown in this example. 

     DEADBEEFDEADBEEFDEADBEEF...<CR><LF>
     B0D0EADSDEADBEEFB0D0EADS...<CR><LF>
     ...<CR><LF>
     DEADBE==<CR><LF>

Parsing is minimalistic to make the whole sucker as fast as possible (not looking at Java's performance at all).

Version:
$Revision: 1.3 $ $Date: 2005/11/11 21:23:44 $ $State: Exp $ $Locker: $
Author:
Harald Albrecht

  • Constructor Details

    • XdrHttpDecodingStream

      public XdrHttpDecodingStream(HttpClientConnection httpClient)
      Constructs a new XdrHttpDecodingStream.
      Parameters:
      httpClient - HTTP client connection from which to read the encoded and embedded ONC/RPC reply message.

  • Method Details

    • getSenderAddress

      public InetAddress getSenderAddress()
      Returns the Internet address of the sender of the current XDR data. This method should only be called after beginDecoding(), otherwise it might return stale information.
      Specified by:
      getSenderAddress in class XdrDecodingStream
      Returns:
      InetAddress of the sender of the current XDR data.

    • getSenderPort

      public int getSenderPort()
      Returns the port number of the sender of the current XDR data. This method should only be called after beginDecoding(), otherwise it might return stale information.
      Specified by:
      getSenderPort in class XdrDecodingStream
      Returns:
      Port number of the sender of the current XDR data.

    • beginDecoding

      public void beginDecoding() throws OncRpcException, IOException
      Initiates decoding of the next XDR record. For HTTP-based XDR we just read the content delivered with the answer to the POST command.
      Specified by:
      beginDecoding in class XdrDecodingStream
      Throws:
      OncRpcException - if an ONC/RPC error occurs.
      IOException - if an I/O error occurs.

    • endDecoding

      public void endDecoding() throws OncRpcException, IOException
      End decoding of the current XDR record. The general contract of endDecoding is that calling it is an indication that the current record is no more interesting to the caller and any allocated data for this record can be freed.

      To help the HTTP connection keeping alive, we swallow all data until we reach the end. If this is not possible, either because the server indicated that it can not keep the connection open, the content length was unknown in advance, or we got an I/O exception, we close the connection.

      Overrides:
      endDecoding in class XdrDecodingStream
      Throws:
      OncRpcException - if an ONC/RPC error occurs.
      IOException - if an I/O error occurs.

    • close

      public void close() throws OncRpcException, IOException
      Closes this decoding XDR stream and releases any system resources associated with this stream. A closed XDR stream cannot perform decoding operations and cannot be reopened.

      This implementation frees the allocated buffer but does not close the associated datagram socket. It only throws away the reference to this socket.

      Overrides:
      close in class XdrDecodingStream
      Throws:
      OncRpcException - if an ONC/RPC error occurs.
      IOException - if an I/O error occurs.

    • xdrDecodeInt

      public int xdrDecodeInt() throws OncRpcException, IOException
      Decodes (aka "deserializes") a "XDR int" value received from a XDR stream. A XDR int is 32 bits wide -- the same width Java's "int" data type has.
      Specified by:
      xdrDecodeInt in class XdrDecodingStream
      Returns:
      The decoded int value.
      Throws:
      OncRpcException - if an ONC/RPC error occurs.
      IOException - if an I/O error occurs.

    • xdrDecodeOpaque

      public byte[] xdrDecodeOpaque(int length) throws OncRpcException, IOException
      Decodes (aka "deserializes") an opaque value, which is nothing more than a series of octets (or 8 bits wide bytes). Because the length of the opaque value is given, we don't need to retrieve it from the XDR stream. This is different from xdrDecodeOpaque(byte[], int, int) where first the length of the opaque value is retrieved from the XDR stream.
      Specified by:
      xdrDecodeOpaque in class XdrDecodingStream
      Parameters:
      length - Length of opaque data to decode.
      Returns:
      Opaque data as a byte vector.
      Throws:
      OncRpcException - if an ONC/RPC error occurs.
      IOException - if an I/O error occurs.

    • xdrDecodeOpaque

      public void xdrDecodeOpaque(byte[] opaque, int offset, int length) throws OncRpcException, IOException
      Decodes (aka "deserializes") a XDR opaque value, which is represented by a vector of byte values, and starts at offset with a length of length. Only the opaque value is decoded, so the caller has to know how long the opaque value will be. The decoded data is always padded to be a multiple of four (because that's what the sender does).
      Specified by:
      xdrDecodeOpaque in class XdrDecodingStream
      Parameters:
      opaque - Byte vector which will receive the decoded opaque value.
      offset - Start offset in the byte vector.
      length - the number of bytes to decode.
      Throws:
      OncRpcException - if an ONC/RPC error occurs.
      IOException - if an I/O error occurs.