Package org.apache.coyote.ajp

Class AjpMessage

java.lang.Object

org.apache.coyote.ajp.AjpMessage

public class AjpMessage
extends java.lang.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 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 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(java.nio.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 java.lang.String	hex(int x)	Convert an integer to a two-character hex string.
protected static java.lang.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 java.lang.Object

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

Field Detail

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 Detail

AjpMessage

public AjpMessage(int packetSize)

Constructs a new AjpMessage with the specified packet size.

Parameters:

packetSize - The size of the packet buffer

Method Detail

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(java.nio.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 java.lang.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 java.lang.String hex(int x)

Convert an integer to a two-character hex string.

Parameters:

x - the integer to convert

Returns:

the hex string