Package org.acplt.oncrpc.web

Class HttpClientConnection

java.lang.Object
org.acplt.oncrpc.web.HttpClientConnection
public class HttpClientConnection extends Object
The class HttpClientConnection provides a simple HTTP/1.1 compliant connection from a client to an HTTP server. This class does not provide a full-blown HTTP connection, but it is rather optimized for what ONC/RPC clients need in order to tunnel ONC remote procedure calls through ordinary HTTP connections, thus penetrating firewalls.

A HttpClientConnection is not that clever as you would first expect. Rather you have to do some things for yourself, like reconnecting dropped connections, and so on. While this sometimes result in more labour on the caller's shoulders, this keeps resource wasting at a minimum, and gives you full control over redirections and other mess -- you do want full control, right?.

For this reason, for instance, an HttpClientConnection does not buffer the whole request before sending it to the server but rather relies on the caller to supply the right content-length information. This avoids unnecessary double buffering but instead creates the bas64 encoded content on-the-fly.

Of course, this client connection object does not touch the content, it just suplies the pipe to swallow the data.

Version:
$Revision: 1.1.1.1 $ $Date: 2003/08/13 12:03:45 $ $State: Exp $ $Locker: $
Author:
Harald Albrecht

  • Nested Class Summary

    Nested Classes
    Modifier and Type
    Class
    Description
    (package private) class 
    HttpClientConnection.GetPropertyPrivilegedAction
     

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    private byte[]
    asciiBuffer
    Buffer receiving ASCII characters from Unicode strings when sending (header) strings to the HTTP server.
    private String
    cachedProxyHost
    Address of proxy host to contact instead of real HTTP server.
    private int
    cachedProxyPort
    Port number of proxy HTTP server.
    private boolean
    chunkedTransfer
    Indicates whether the HTTP server send its reply using the chunked transfer encoding.
    private String
    contentType
    Type of content sent by HTTP server.
    static final byte[]
    CRLF
     
    private boolean
    finalChunkSeen
    Indicates whether the end-of-chunks chunk has been read (whow, another one for the Purlitzer price).
    private char[]
    headerLine
    Dynamically growing buffer used during header parsing.
    private String
    hostname
    Host name of HTTP server to contact in the form of www.acplt.org.
    private static final int
    HTTP_DEAD
     
    static final int
    HTTP_DEFAULTPORT
    Default port where HTTP servers listen for incomming requests.
    private static final int
    HTTP_IDLE
     
    private static final int
    HTTP_RECEIVING
     
    private static final int
    HTTP_SENDING
     
    private InputStream
    in
     
    private boolean
    keepAlive
     
    private int
    mode
    Indicates sending/receiving mode of the HTTP connection.
    private OutputStream
    out
    Buffered output stream used for sending the HTTP headers.
    private int
    port
    Port number where to contact the HTTP server.
    private int
    remainingChunkLength
    Contains the amount of data still to be read for the current chunk.
    private int
    remainingContentLength
    Indicates the amount of content data which still has to be sent or received.
    private int
    responseCode
    Contains the HTTP response code from the last request sent to the HTTP server.
    private Socket
    socket
    TCP/IP socket for communication with the HTTP server.
    private int
    timeout
    Timeout (in milliseconds) for communication with an HTTP server.
    private boolean
    useProxy
    Indicates whether a proxy HTTP server needs to be contacted in order to reach the real HTTP server.
    private String
    userAgentId
     

  • Constructor Summary

    Constructors
    Constructor
    Description
    HttpClientConnection(String hostname)
    Constructs a new HttpClientConnection.
    HttpClientConnection(String hostname, int port)
    Constructs a new HttpClientConnection.

  • Method Summary

    Modifier and Type
    Method
    Description
    int
    beginDecoding()
    Begin receiving the content sent by the HTTP server.
    void
    beginPostRequest(String path, String mimeType, int contentLength)
    Starts a new HTTP "POST" request and sends all necessary HTTP header fields.
    void
    close()
    Closes the connection to the HTTP server and frees up some resources.
    private void
    connect()
    Connects to the HTTP server.
    void
    endDecoding()
    This method silently discards any unread content, if the caller has yet not read all content.
    void
    endPostRequest()
    Ends the HTTP "POST" request.
    String
    getContentType()
    Returns the content type (MIME type, charset, etc.).
    boolean
    getKeepAlive()
     
    private String
    getProxyHost()
    Retrieves the host name where the HTTP proxy server resided from the system properties.
    private int
    getProxyPort()
    Retrieves the port number where the HTTP proxy server resides from the system properties.
    int
    getRemainingContentLength()
    Returns amount of content still available (to be read).
    int
    getResponseCode()
     
    int
    getTimeout()
    Retrieve the current timeout set for remote procedure calls.
    protected void
    handleOption(String option, String value)
    Handle options sent by the HTTP server.
    int
    readContentBytes(byte[] buffer, int offset, int length)
    Read content sent by the HTTP server.
    private boolean
    readHeaderLine(String[] keyvalue)
    Read in a header line coming over the HTTP connection from the server.
    private int
    readHeaders()
    Read the HTTP headers sent by the servers and also parse them at the same time.
    private String
    readLine()
    Read exactly one line, termined by CRLF or either CR or LF, and return it.
    void
    setTimeout(int milliseconds)
    Set the timout for sending or receiving information to/from the HTTP server.
    private void
    write(String s)
    Writes an ASCII string to the HTTP server (this is buffered first).
    void
    writeContentBytes(byte[] bytes, int offset, int length)
    Send (part) of the content to the HTTP server.
    private void
    writeln(String s)
    Writes an ASCII string and appends a line termination in the form of CR followed by LF.

    Methods inherited from class java.lang.Object

    clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

  • Field Details

    • HTTP_DEFAULTPORT

      public static final int HTTP_DEFAULTPORT
      Default port where HTTP servers listen for incomming requests. This is just a convenience definition to make the code more readable.
      See Also:

    • hostname

      private String hostname
      Host name of HTTP server to contact in the form of www.acplt.org.

    • port

      private int port
      Port number where to contact the HTTP server. This defaults to the standard port where HTTP servers are expected: port 80.

    • socket

      private Socket socket
      TCP/IP socket for communication with the HTTP server.

    • timeout

      private int timeout
      Timeout (in milliseconds) for communication with an HTTP server.

    • keepAlive

      private boolean keepAlive

    • chunkedTransfer

      private boolean chunkedTransfer
      Indicates whether the HTTP server send its reply using the chunked transfer encoding.

    • remainingChunkLength

      private int remainingChunkLength
      Contains the amount of data still to be read for the current chunk.

    • finalChunkSeen

      private boolean finalChunkSeen
      Indicates whether the end-of-chunks chunk has been read (whow, another one for the Purlitzer price).

    • contentType

      private String contentType
      Type of content sent by HTTP server.

    • out

      private OutputStream out
      Buffered output stream used for sending the HTTP headers. This stream is not used to send content in an HTTP request.

    • in

      private InputStream in

    • responseCode

      private int responseCode
      Contains the HTTP response code from the last request sent to the HTTP server.

    • asciiBuffer

      private byte[] asciiBuffer
      Buffer receiving ASCII characters from Unicode strings when sending (header) strings to the HTTP server.

    • headerLine

      private char[] headerLine
      Dynamically growing buffer used during header parsing.

    • userAgentId

      private String userAgentId

    • HTTP_DEAD

      private static final int HTTP_DEAD
      See Also:

    • HTTP_IDLE

      private static final int HTTP_IDLE
      See Also:

    • HTTP_SENDING

      private static final int HTTP_SENDING
      See Also:

    • HTTP_RECEIVING

      private static final int HTTP_RECEIVING
      See Also:

    • mode

      private int mode
      Indicates sending/receiving mode of the HTTP connection.

    • remainingContentLength

      private int remainingContentLength
      Indicates the amount of content data which still has to be sent or received.

    • CRLF

      public static final byte[] CRLF

    • useProxy

      private boolean useProxy
      Indicates whether a proxy HTTP server needs to be contacted in order to reach the real HTTP server.

    • cachedProxyHost

      private String cachedProxyHost
      Address of proxy host to contact instead of real HTTP server.

    • cachedProxyPort

      private int cachedProxyPort
      Port number of proxy HTTP server.

  • Constructor Details

    • HttpClientConnection

      public HttpClientConnection(String hostname)
      Constructs a new HttpClientConnection. The port used on the HTTP server side is the default HTTP port, 80.
      Parameters:
      hostname - name (DNS name or IP dotted address) of host running a HTTP server to which we want to connect to.

    • HttpClientConnection

      public HttpClientConnection(String hostname, int port)
      Constructs a new HttpClientConnection.
      Parameters:
      hostname - name (DNS name or IP dotted address) of host running a HTTP server to which we should connect to.
      port - Port number where the HTTP server can be contacted.

  • Method Details

    • close

      public void close()
      Closes the connection to the HTTP server and frees up some resources. After calling close it is still possible to open a new connection to the HTTP server once again.

    • beginPostRequest

      public void beginPostRequest(String path, String mimeType, int contentLength) throws IOException
      Starts a new HTTP "POST" request and sends all necessary HTTP header fields. Next, the caller can send lots of content using the writeContentBytes(byte[], int, int) method. Finally, to finish the request he has to call the endPostRequest() method.
      Parameters:
      path - Path to server object which handles the POST request. For instance, this can be a CGI script (although it better should not be one, except in the case of FAST CGI).
      mimeType - MIME-classified type of content to be sent.
      contentLength - Length of content to be sent. If negative, the length is not known in advance. In this case, keeping the connection alive is not possible, so callers should avoid this situation, if possible.
      Throws:
      IOException - if an I/O exception occurs when sending the HTTP headers. In this case the connection is closed automatically and the caller must not send any content. However, the caller is free to give the request another try by calling beginEncoding again, thus opening a new HTTP connection.

    • writeContentBytes

      public void writeContentBytes(byte[] bytes, int offset, int length) throws IOException
      Send (part) of the content to the HTTP server. Note that the output is done unbuffered, so callers should write their content in large chunks to avoid the calling overhead for sending data.
      Parameters:
      bytes - The data.
      offset - Start offset in the data.
      length - Number of bytes to write.
      Throws:
      RuntimeException - if too much content was sent.
      IOException - if an I/O error occurs.
      NullPointerException - if bytes is null.
      IndexOutOfBoundsException - if offset is negative, or length is negative, or offset + length is greater than the length of the array bytes.

    • endPostRequest

      public void endPostRequest() throws IOException
      Ends the HTTP "POST" request. The next logical step for a caller is then to call ... #FIXME
      Throws:
      IOException

    • handleOption

      protected void handleOption(String option, String value)
      Handle options sent by the HTTP server.

      Currently the following options are handled by this class:

      • Content-Length -- length of content following the header section
      • Content-Type -- type of content sent
      • Proxy-Connection -- handle keep-alive request
      • Connection -- handle keep-alive request
      • Transfer-Encoding -- transfer encoding choosen by HTTP server
      Parameters:
      option - Name of option sent by HTTP server.
      value - Value of option.

    • readHeaders

      private int readHeaders() throws IOException
      Read the HTTP headers sent by the servers and also parse them at the same time.
      Returns:
      HTTP status code.
      Throws:
      IOException

    • readHeaderLine

      private boolean readHeaderLine(String[] keyvalue) throws IOException
      Read in a header line coming over the HTTP connection from the server.
      Parameters:
      keyvalue - An array with room for either exactly one or two strings, receiving the header option and optionally its value. If only room for a single return string is supplied, then readHeaderLine will only read in the header line (like the first HTTP header) without separating the options's value from its name. If a header option has no option, then null is returned as the value string.
      Returns:
      false if the end of the headers has been reached.
      Throws:
      IOException

    • readLine

      private String readLine() throws IOException
      Read exactly one line, termined by CRLF or either CR or LF, and return it.
      Returns:
      Line without the terminating CR, LF or CRLF.
      Throws:
      IOException

    • beginDecoding

      public int beginDecoding() throws IOException
      Begin receiving the content sent by the HTTP server. This method blocks until at least the HTTP header section has been received or until the connection times out.
      Returns:
      HTTP server response code (status code).
      Throws:
      IOException

    • getContentType

      public String getContentType()
      Returns the content type (MIME type, charset, etc.).
      Returns:
      content type

    • readContentBytes

      public int readContentBytes(byte[] buffer, int offset, int length) throws IOException
      Read content sent by the HTTP server. This method also handles the HTTP/1.1 chunked transfer encoding if the HTTP server insisted on using it. If only chunked transfer encoding has been introduced with the first official 0.9 protocol version of HTTP, it would have made sending ONC/RPC requests much easier, because we would not need to buffer the while request before sending it just to know its exact length. Unfortunately, chunking has only been introduced lately so we can not expect servers and especially proxies to handle it. Sigh.
      Parameters:
      buffer - Buffer to receive the content sent by the HTTP server.
      offset - Start offset in the buffer.
      length - Number of bytes to receive.
      Throws:
      ProtocolException - if not enough content was available (the caller attempted to read more data than available) or if we received junk information violating the HTTP protocol specification.
      IOException - if an I/O error occurs.
      NullPointerException - if bytes is null.
      IndexOutOfBoundsException - if offset is negative, or length is negative, or offset + length is greater than the length of the array bytes.

    • getRemainingContentLength

      public int getRemainingContentLength()
      Returns amount of content still available (to be read). This always shows the remaining amount and is updated whenever content is read using readContentBytes(byte[], int, int).
      Returns:
      Amount of content available.

    • endDecoding

      public void endDecoding() throws IOException

      This method silently discards any unread content, if the caller has yet not read all content.

      Throws:
      IOException

    • setTimeout

      public void setTimeout(int milliseconds)
      Set the timout for sending or receiving information to/from the HTTP server.
      Parameters:
      milliseconds - Timeout in milliseconds.

    • getTimeout

      public int getTimeout()
      Retrieve the current timeout set for remote procedure calls. A timeout of zero indicates batching calls (no reply message is expected).
      Returns:
      Current timeout.

    • getResponseCode

      public int getResponseCode()

    • getKeepAlive

      public boolean getKeepAlive()

    • connect

      private void connect() throws IOException
      Connects to the HTTP server. In case an HTTP proxy has been configured, this connects to the proxy instead.

      If the connection is in keep-alive mode and already open, then the connection is reused.

      Throws:
      SecurityException - if a security manager exists and its checkConnect method does not allow the connect operation.
      IOException

    • write

      private void write(String s) throws IOException
      Writes an ASCII string to the HTTP server (this is buffered first).
      Parameters:
      s - String to write.
      Throws:
      IOException

    • writeln

      private void writeln(String s) throws IOException
      Writes an ASCII string and appends a line termination in the form of CR followed by LF.
      Parameters:
      s - String to write.
      Throws:
      IOException

    • getProxyHost

      private String getProxyHost()
      Retrieves the host name where the HTTP proxy server resided from the system properties.
      Returns:
      Name of proxy host or null if no proxy has been configured.

    • getProxyPort

      private int getProxyPort()
      Retrieves the port number where the HTTP proxy server resides from the system properties. If no port number has been configured for the HTTP proxy, then the default http port number of 80 is returned.
      Returns:
      Port number of HTTP proxy server.