AjpMessage.java
/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.coyote.ajp;
import java.nio.ByteBuffer;
import org.apache.juli.logging.Log;
import org.apache.juli.logging.LogFactory;
import org.apache.tomcat.util.buf.ByteChunk;
import org.apache.tomcat.util.buf.HexUtils;
import org.apache.tomcat.util.buf.MessageBytes;
import org.apache.tomcat.util.res.StringManager;
/**
* 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.
*
* @author Henri Gomez
* @author Dan Milstein
* @author Keith Wannamaker
* @author Kevin Seguin
* @author Costin Manolache
*/
public class AjpMessage {
private static final Log log = LogFactory.getLog(AjpMessage.class);
/**
* The string manager for this package.
*/
protected static final StringManager sm = StringManager.getManager(AjpMessage.class);
// ------------------------------------------------------------ Constructor
public AjpMessage(int packetSize) {
buf = new byte[packetSize];
}
// ----------------------------------------------------- Instance Variables
/**
* Fixed size buffer.
*/
protected final byte buf[];
/**
* The current read or write position in the buffer.
*/
protected int pos;
/**
* 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.
*/
protected int len;
// --------------------------------------------------------- Public Methods
/**
* 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).
*/
public void reset() {
len = 4;
pos = 4;
}
/**
* 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.
*/
public void end() {
len = pos;
int dLen = len - 4;
buf[0] = (byte) 0x41;
buf[1] = (byte) 0x42;
buf[2] = (byte) ((dLen >>> 8) & 0xFF);
buf[3] = (byte) (dLen & 0xFF);
}
/**
* Return the underlying byte buffer.
*
* @return The buffer
*/
public byte[] getBuffer() {
return buf;
}
/**
* Return the current message length.
*
* @return 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).
*/
public int getLen() {
return len;
}
/**
* Add a short integer (2 bytes) to the message.
*
* @param val The integer to append
*/
public void appendInt(int val) {
buf[pos++] = (byte) ((val >>> 8) & 0xFF);
buf[pos++] = (byte) (val & 0xFF);
}
/**
* Append a byte (1 byte) to the message.
*
* @param val The byte value to append
*/
public void appendByte(int val) {
buf[pos++] = (byte) val;
}
/**
* Write a MessageBytes out at the current write position. A null MessageBytes is encoded as a string with length 0.
*
* @param mb The data to write
*/
public void appendBytes(MessageBytes mb) {
if (mb == null) {
log.error(sm.getString("ajpmessage.null"), new NullPointerException());
appendInt(0);
appendByte(0);
return;
}
if (mb.getType() != MessageBytes.T_BYTES) {
mb.toBytes();
ByteChunk bc = mb.getByteChunk();
// Need to filter out CTLs excluding TAB. ISO-8859-1 and UTF-8
// values will be OK. Strings using other encodings may be
// corrupted.
byte[] buffer = bc.getBuffer();
for (int i = bc.getOffset(); i < bc.getLength(); i++) {
// byte values are signed i.e. -128 to 127
// The values are used unsigned. 0 to 31 are CTLs so they are
// filtered (apart from TAB which is 9). 127 is a control (DEL).
// The values 128 to 255 are all OK. Converting those to signed
// gives -128 to -1.
if ((buffer[i] > -1 && buffer[i] <= 31 && buffer[i] != 9) || buffer[i] == 127) {
buffer[i] = ' ';
}
}
}
appendByteChunk(mb.getByteChunk());
}
/**
* Write a ByteChunk out at the current write position. A null ByteChunk is encoded as a string with length 0.
*
* @param bc The data to write
*/
public void appendByteChunk(ByteChunk bc) {
if (bc == null) {
log.error(sm.getString("ajpmessage.null"), new NullPointerException());
appendInt(0);
appendByte(0);
return;
}
appendBytes(bc.getBytes(), bc.getStart(), bc.getLength());
}
/**
* 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 <B>not</B> included
* in the encoded length).
*
* @param b The array from which to copy bytes.
* @param off The offset into the array at which to start copying
* @param numBytes The number of bytes to copy.
*/
public void appendBytes(byte[] b, int off, int numBytes) {
if (checkOverflow(numBytes)) {
return;
}
appendInt(numBytes);
System.arraycopy(b, off, buf, pos, numBytes);
pos += numBytes;
appendByte(0);
}
/**
* 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 <B>not</B> included
* in the encoded length).
*
* @param b The ByteBuffer from which to copy bytes.
*/
public void appendBytes(ByteBuffer b) {
int numBytes = b.remaining();
if (checkOverflow(numBytes)) {
return;
}
appendInt(numBytes);
b.get(buf, pos, numBytes);
pos += numBytes;
appendByte(0);
}
private boolean checkOverflow(int numBytes) {
if (pos + numBytes + 3 > buf.length) {
log.error(sm.getString("ajpmessage.overflow", "" + numBytes, "" + pos),
new ArrayIndexOutOfBoundsException());
if (log.isDebugEnabled()) {
dump("Overflow/coBytes");
}
return true;
}
return false;
}
/**
* 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.
*
* @return The integer value read from the message
*/
public int getInt() {
int b1 = buf[pos++] & 0xFF;
int b2 = buf[pos++] & 0xFF;
validatePos(pos);
return (b1 << 8) + b2;
}
public int peekInt() {
validatePos(pos + 2);
int b1 = buf[pos] & 0xFF;
int b2 = buf[pos + 1] & 0xFF;
return (b1 << 8) + b2;
}
public byte getByte() {
byte res = buf[pos++];
validatePos(pos);
return res;
}
public void getBytes(MessageBytes mb) {
doGetBytes(mb, true);
}
public void getBodyBytes(MessageBytes mb) {
doGetBytes(mb, false);
}
private void doGetBytes(MessageBytes mb, boolean terminated) {
int length = getInt();
if (length == 0xFFFF || length == -1) {
mb.recycle();
return;
}
if (terminated) {
validatePos(pos + length + 1);
} else {
validatePos(pos + length);
}
mb.setBytes(buf, pos, length);
mb.getCharChunk().recycle(); // not valid anymore
pos += length;
if (terminated) {
pos++; // Skip the terminating \0
}
}
/**
* 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.
*
* @return The long value read from the message
*/
public int getLongInt() {
int b1 = buf[pos++] & 0xFF; // No swap, Java order
b1 <<= 8;
b1 |= (buf[pos++] & 0xFF);
b1 <<= 8;
b1 |= (buf[pos++] & 0xFF);
b1 <<= 8;
b1 |= (buf[pos++] & 0xFF);
validatePos(pos);
return b1;
}
public int processHeader(boolean toContainer) {
pos = 0;
int mark = getInt();
len = getInt();
// Verify message signature
if ((toContainer && mark != 0x1234) || (!toContainer && mark != 0x4142)) {
log.error(sm.getString("ajpmessage.invalid", "" + mark));
if (log.isTraceEnabled()) {
dump("In");
}
return -1;
}
if (log.isTraceEnabled()) {
log.trace("Received " + len + " " + buf[0]);
}
return len;
}
private void dump(String prefix) {
if (log.isTraceEnabled()) {
log.trace(prefix + ": " + HexUtils.toHexString(buf) + " " + pos + "/" + (len + 4));
}
int max = pos;
if (len + 4 > pos) {
max = len + 4;
}
if (max > 1000) {
max = 1000;
}
if (log.isTraceEnabled()) {
for (int j = 0; j < max; j += 16) {
log.trace(hexLine(buf, j, len));
}
}
}
private void validatePos(int posToTest) {
if (posToTest > len + 4) {
// Trying to read data beyond the end of the AJP message
throw new ArrayIndexOutOfBoundsException(sm.getString("ajpMessage.invalidPos", Integer.valueOf(posToTest)));
}
}
// ------------------------------------------------------ Protected Methods
protected static String hexLine(byte buf[], int start, int len) {
StringBuilder sb = new StringBuilder();
for (int i = start; i < start + 16; i++) {
if (i < len + 4) {
sb.append(hex(buf[i])).append(' ');
} else {
sb.append(" ");
}
}
sb.append(" | ");
for (int i = start; i < start + 16 && i < len + 4; i++) {
if (!Character.isISOControl((char) buf[i])) {
sb.append(Character.valueOf((char) buf[i]));
} else {
sb.append('.');
}
}
return sb.toString();
}
protected static String hex(int x) {
String h = Integer.toHexString(x);
if (h.length() == 1) {
h = "0" + h;
}
return h.substring(h.length() - 2);
}
}