Class AjpMessage

java.lang.Object
org.apache.coyote.ajp.AjpMessage
public class AjpMessage extends Object
A single packet for communication between the web server and the container. Designed to be reused many times with no creation of garbage. Understands the format of data types for these packets. Can be used (somewhat confusingly) for both incoming and outgoing packets.

  • Field Summary

    Fields
    Modifier and Type
    Field
    Description
    protected final byte[]
    buf
    Fixed size buffer.
    protected int
    len
    This actually means different things depending on whether the packet is read or write.
    protected int
    pos
    The current read or write position in the buffer.
    protected static final StringManager
    sm
    The string manager for this package.

  • Constructor Summary

    Constructors
    Constructor
    Description
    AjpMessage(int packetSize)
    Constructs a new AjpMessage with the specified packet size.

  • Method Summary

    Modifier and Type
    Method
    Description
    void
    appendByte(int val)
    Append a byte (1 byte) to the message.
    void
    appendByteChunk(ByteChunk bc)
    Write a ByteChunk out at the current write position.
    void
    appendBytes(byte[] b, int off, int numBytes)
    Copy a chunk of bytes into the packet, starting at the current write position.
    void
    appendBytes(ByteBuffer b)
    Copy a chunk of bytes into the packet, starting at the current write position.
    void
    appendBytes(MessageBytes mb)
    Write a MessageBytes out at the current write position.
    void
    appendInt(int val)
    Add a short integer (2 bytes) to the message.
    void
    end()
    For a packet to be sent to the web server, finish the process of accumulating data and write the length of the data payload into the header.
    void
    getBodyBytes(MessageBytes mb)
    Read a non-terminated string of bytes from the packet.
    byte[]
    getBuffer()
    Return the underlying byte buffer.
    byte
    getByte()
    Read a single byte from the packet and advance the read position.
    void
    getBytes(MessageBytes mb)
    Read a null-terminated string of bytes from the packet.
    int
    getInt()
    Read an integer from packet, and advance the read position past it.
    int
    getLen()
    Return the current message length.
    int
    getLongInt()
    Read a 32 bits integer from packet, and advance the read position past it.
    protected static String
    hex(int x)
    Convert an integer to a two-character hex string.
    protected static String
    hexLine(byte[] buf, int start, int len)
    Generate a hex dump line for debugging.
    int
    peekInt()
    Peek at the next integer without advancing the read position.
    int
    processHeader(boolean toContainer)
    Process the AJP message header, validating the message signature.
    void
    reset()
    Prepare this packet for accumulating a message from the container to the web server.

    Methods inherited from class Object

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

  • Field Details

    • sm

      protected static final StringManager sm
      The string manager for this package.

    • buf

      protected final byte[] buf
      Fixed size buffer.

    • pos

      protected int pos
      The current read or write position in the buffer.

    • len

      protected int len
      This actually means different things depending on whether the packet is read or write. For read, it's the length of the payload (excluding the header). For write, it's the length of the packet as a whole (counting the header). Oh, well.

  • Constructor Details

    • AjpMessage

      public AjpMessage(int packetSize)
      Constructs a new AjpMessage with the specified packet size.
      Parameters:
      packetSize - The size of the packet buffer

  • Method Details

    • reset

      public void reset()
      Prepare this packet for accumulating a message from the container to the web server. Set the write position to just after the header (but leave the length unwritten, because it is as yet unknown).

    • end

      public void end()
      For a packet to be sent to the web server, finish the process of accumulating data and write the length of the data payload into the header.

    • getBuffer

      public byte[] getBuffer()
      Return the underlying byte buffer.
      Returns:
      The buffer

    • getLen

      public int getLen()
      Return the current message length.
      Returns:
      For read, it's the length of the payload (excluding the header). For write, it's the length of the packet as a whole (counting the header).

    • appendInt

      public void appendInt(int val)
      Add a short integer (2 bytes) to the message.
      Parameters:
      val - The integer to append

    • appendByte

      public void appendByte(int val)
      Append a byte (1 byte) to the message.
      Parameters:
      val - The byte value to append

    • appendBytes

      public void appendBytes(MessageBytes mb)
      Write a MessageBytes out at the current write position. A null MessageBytes is encoded as a string with length 0.
      Parameters:
      mb - The data to write

    • appendByteChunk

      public void appendByteChunk(ByteChunk bc)
      Write a ByteChunk out at the current write position. A null ByteChunk is encoded as a string with length 0.
      Parameters:
      bc - The data to write

    • appendBytes

      public void appendBytes(byte[] b, int off, int numBytes)
      Copy a chunk of bytes into the packet, starting at the current write position. The chunk of bytes is encoded with the length in two bytes first, then the data itself, and finally a terminating \0 (which is not included in the encoded length).
      Parameters:
      b - The array from which to copy bytes.
      off - The offset into the array at which to start copying
      numBytes - The number of bytes to copy.

    • appendBytes

      public void appendBytes(ByteBuffer b)
      Copy a chunk of bytes into the packet, starting at the current write position. The chunk of bytes is encoded with the length in two bytes first, then the data itself, and finally a terminating \0 (which is not included in the encoded length).
      Parameters:
      b - The ByteBuffer from which to copy bytes.

    • getInt

      public int getInt()
      Read an integer from packet, and advance the read position past it. Integers are encoded as two unsigned bytes with the high-order byte first, and, as far as I can tell, in little-endian order within each byte.
      Returns:
      The integer value read from the message

    • peekInt

      public int peekInt()
      Peek at the next integer without advancing the read position.
      Returns:
      The integer value at the current read position

    • getByte

      public byte getByte()
      Read a single byte from the packet and advance the read position.
      Returns:
      The byte value read from the message

    • getBytes

      public void getBytes(MessageBytes mb)
      Read a null-terminated string of bytes from the packet.
      Parameters:
      mb - The MessageBytes to populate with the read bytes

    • getBodyBytes

      public void getBodyBytes(MessageBytes mb)
      Read a non-terminated string of bytes from the packet.
      Parameters:
      mb - The MessageBytes to populate with the read bytes

    • getLongInt

      public int getLongInt()
      Read a 32 bits integer from packet, and advance the read position past it. Integers are encoded as four unsigned bytes with the high-order byte first, and, as far as I can tell, in little-endian order within each byte.
      Returns:
      The long value read from the message

    • processHeader

      public int processHeader(boolean toContainer)
      Process the AJP message header, validating the message signature.
      Parameters:
      toContainer - true if the message is from the web server to the container, false if from the container to the web server
      Returns:
      The length of the payload, or -1 if the message signature is invalid

    • hexLine

      protected static String hexLine(byte[] buf, int start, int len)
      Generate a hex dump line for debugging.
      Parameters:
      buf - The byte buffer
      start - The starting offset
      len - The current message length
      Returns:
      A string representation of the hex dump line

    • hex

      protected static String hex(int x)
      Convert an integer to a two-character hex string.
      Parameters:
      x - the integer to convert
      Returns:
      the hex string