Java tutorial
/* * ==================================================================== * * The Apache Software License, Version 1.1 * * Copyright (c) 1999 The Apache Software Foundation. All rights * reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in * the documentation and/or other materials provided with the * distribution. * * 3. The end-user documentation included with the redistribution, if * any, must include the following acknowlegement: * "This product includes software developed by the * Apache Software Foundation (http://www.apache.org/)." * Alternately, this acknowlegement may appear in the software itself, * if and wherever such third-party acknowlegements normally appear. * * 4. The names "The Jakarta Project", "Tomcat", and "Apache Software * Foundation" must not be used to endorse or promote products derived * from this software without prior written permission. For written * permission, please contact apache@apache.org. * * 5. Products derived from this software may not be called "Apache" * nor may "Apache" appear in their names without prior written * permission of the Apache Group. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESSED OR IMPLIED * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE * DISCLAIMED. IN NO EVENT SHALL THE APACHE SOFTWARE FOUNDATION OR * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF * USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * ==================================================================== * * This software consists of voluntary contributions made by many * individuals on behalf of the Apache Software Foundation. For more * information on the Apache Software Foundation, please see * <http://www.apache.org/>. * * [Additional notices, if required by prior licensing conditions] * */ package org.apache.jk.common; import java.io.IOException; import org.apache.jk.core.Msg; import org.apache.tomcat.util.buf.ByteChunk; import org.apache.tomcat.util.buf.MessageBytes; /** * 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. * * @see Ajp14/Ajp13Packet * * @author Henri Gomez [hgomez@apache.org] * @author Dan Milstein [danmil@shore.net] * @author Keith Wannamaker [Keith@Wannamaker.org] * @author Kevin Seguin * @author Costin Manolache */ public class MsgAjp extends Msg { private static org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory.getLog(MsgAjp.class); // that's the original buffer size in ajp13 - otherwise we'll get interoperability problems. private byte buf[] = new byte[8 * 1024]; // The current read or write position in the buffer private 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. */ private int len; /** * 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); } public byte[] getBuffer() { return buf; } public int getLen() { return len; } // ============ Data Writing Methods =================== /** * Add an int. * * @param val The integer to write. */ public void appendInt(int val) { buf[pos++] = (byte) ((val >>> 8) & 0xFF); buf[pos++] = (byte) (val & 0xFF); } public void appendByte(int val) { buf[pos++] = (byte) val; } public void appendLongInt(int val) { buf[pos++] = (byte) ((val >>> 24) & 0xFF); buf[pos++] = (byte) ((val >>> 16) & 0xFF); buf[pos++] = (byte) ((val >>> 8) & 0xFF); buf[pos++] = (byte) (val & 0xFF); } /** * Write a String out at the current write position. Strings are * encoded with the length in two bytes first, then the string, and * then a terminating \0 (which is <B>not</B> included in the * encoded length). The terminator is for the convenience of the C * code, where it saves a round of copying. A null string is * encoded as a string with length 0. */ public void appendBytes(MessageBytes mb) throws IOException { if (mb == null || mb.isNull()) { appendInt(0); appendByte(0); return; } // XXX Convert !! ByteChunk bc = mb.getByteChunk(); appendByteChunk(bc); } public void appendByteChunk(ByteChunk bc) throws IOException { if (bc == null) { log.error("appendByteChunk() null"); appendInt(0); appendByte(0); return; } byte[] bytes = bc.getBytes(); int start = bc.getStart(); appendInt(bc.getLength()); cpBytes(bytes, start, bc.getLength()); 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 array from which to copy bytes. * @param off The offset into the array at which to start copying * @param len The number of bytes to copy. */ public void appendBytes(byte b[], int off, int numBytes) { appendInt(numBytes); cpBytes(b, off, numBytes); appendByte(0); } private void cpBytes(byte b[], int off, int numBytes) { if (pos + numBytes >= buf.length) { log.error("Buffer overflow: buffer.len=" + buf.length + " pos=" + pos + " data=" + numBytes); dump("Overflow/coBytes"); log.error("Overflow ", new Throwable()); return; } System.arraycopy(b, off, buf, pos, numBytes); pos += numBytes; // buf[pos + numBytes] = 0; // Terminating \0 } // ============ Data Reading Methods =================== /** * 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. */ public int getInt() { int b1 = buf[pos++] & 0xFF; // No swap, Java order int b2 = buf[pos++] & 0xFF; return (b1 << 8) + b2; } public int peekInt() { int b1 = buf[pos] & 0xFF; // No swap, Java order int b2 = buf[pos + 1] & 0xFF; return (b1 << 8) + b2; } public byte getByte() { byte res = buf[pos++]; return res; } public byte peekByte() { byte res = buf[pos]; return res; } public void getBytes(MessageBytes mb) { int length = getInt(); if ((length == 0xFFFF) || (length == -1)) { mb.setString(null); return; } mb.setBytes(buf, pos, length); pos += length; pos++; // Skip the terminating \0 } /** * Copy a chunk of bytes from the packet into an array and advance * the read position past the chunk. See appendBytes() for details * on the encoding. * * @return The number of bytes copied. */ public int getBytes(byte dest[]) { int length = getInt(); if (length > buf.length) { // XXX Should be if(pos + length > buff.legth)? log.error("getBytes() buffer overflow " + length + " " + buf.length); } if ((length == 0xFFFF) || (length == -1)) { log.info("Null string " + length); return 0; } System.arraycopy(buf, pos, dest, 0, length); pos += length; pos++; // Skip terminating \0 XXX I believe this is wrong but harmless return length; } /** * 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. */ 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); return b1; } public int getHeaderLength() { return 4; } public int processHeader() { pos = 0; int mark = getInt(); len = getInt(); if (mark != 0x1234 && mark != 0x4142) { // XXX Logging log.error("BAD packet signature " + mark); dump("In: "); return -1; } if (log.isDebugEnabled()) log.debug("Received " + len + " " + buf[0]); return len; } public void dump(String msg) { log.debug(msg + ": " + buf + " " + pos + "/" + (len + 4)); int max = pos; if (len + 4 > pos) max = len + 4; if (max > 1000) max = 1000; for (int j = 0; j < max; j += 16) System.out.println(hexLine(buf, j, len)); } /* -------------------- Utilities -------------------- */ // XXX Move to util package public static String hexLine(byte buf[], int start, int len) { StringBuffer sb = new StringBuffer(); for (int i = start; i < start + 16; i++) { if (i < len + 4) sb.append(hex(buf[i]) + " "); else sb.append(" "); } sb.append(" | "); for (int i = start; i < start + 16 && i < len + 4; i++) { if (!Character.isISOControl((char) buf[i])) sb.append(new Character((char) buf[i])); else sb.append("."); } return sb.toString(); } private static String hex(int x) { // if( x < 0) x=256 + x; String h = Integer.toHexString(x); if (h.length() == 1) h = "0" + h; return h.substring(h.length() - 2); } }