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/*
 * Copyright 2012 The Netty Project
 *
 * The Netty Project 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.jboss.netty.handler.codec.http;

import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
import org.jboss.netty.channel.Channel;
import org.jboss.netty.channel.ChannelHandlerContext;
import org.jboss.netty.channel.ChannelPipeline;
import org.jboss.netty.handler.codec.frame.TooLongFrameException;
import org.jboss.netty.handler.codec.replay.ReplayingDecoder;

import java.util.List;

/**
 * Decodes {@link ChannelBuffer}s into {@link HttpMessage}s and
 * {@link HttpChunk}s.
 *
 * 

Parameters that prevents excessive memory consumption

* * * * * * * * * * * * * * * * *
NameMeaning
{@code maxInitialLineLength}The maximum length of the initial line * (e.g. {@code "GET / HTTP/1.0"} or {@code "HTTP/1.0 200 OK"}) * If the length of the initial line exceeds this value, a * {@link TooLongFrameException} will be raised.
{@code maxHeaderSize}The maximum length of all headers. If the sum of the length of each * header exceeds this value, a {@link TooLongFrameException} will be raised.
{@code maxChunkSize}The maximum length of the content or each chunk. If the content length * (or the length of each chunk) exceeds this value, the content or chunk * will be split into multiple {@link HttpChunk}s whose length is * {@code maxChunkSize} at maximum.
* *

Chunked Content

* * If the content of an HTTP message is greater than {@code maxChunkSize} or * the transfer encoding of the HTTP message is 'chunked', this decoder * generates one {@link HttpMessage} instance and its following * {@link HttpChunk}s per single HTTP message to avoid excessive memory * consumption. For example, the following HTTP message: *
 * GET / HTTP/1.1
 * Transfer-Encoding: chunked
 *
 * 1a
 * abcdefghijklmnopqrstuvwxyz
 * 10
 * 1234567890abcdef
 * 0
 * Content-MD5: ...
 * [blank line]
 * 
* triggers {@link HttpRequestDecoder} to generate 4 objects: *
    *
  1. An {@link HttpRequest} whose {@link HttpMessage#isChunked() chunked} * property is {@code true},
  2. *
  3. The first {@link HttpChunk} whose content is {@code 'abcdefghijklmnopqrstuvwxyz'},
  4. *
  5. The second {@link HttpChunk} whose content is {@code '1234567890abcdef'}, and
  6. *
  7. An {@link HttpChunkTrailer} which marks the end of the content.
  8. *
* * If you prefer not to handle {@link HttpChunk}s by yourself for your * convenience, insert {@link HttpChunkAggregator} after this decoder in the * {@link ChannelPipeline}. However, please note that your server might not * be as memory efficient as without the aggregator. * *

Extensibility

* * Please note that this decoder is designed to be extended to implement * a protocol derived from HTTP, such as * RTSP and * ICAP. * To implement the decoder of such a derived protocol, extend this class and * implement all abstract methods properly. * @apiviz.landmark */ public abstract class HttpMessageDecoder extends ReplayingDecoder { private final int maxInitialLineLength; private final int maxHeaderSize; private final int maxChunkSize; private HttpMessage message; private ChannelBuffer content; private long chunkSize; private int headerSize; private int contentRead; /** * The internal state of {@link HttpMessageDecoder}. * Internal use only. * @apiviz.exclude */ protected enum State { SKIP_CONTROL_CHARS, READ_INITIAL, READ_HEADER, READ_VARIABLE_LENGTH_CONTENT, READ_VARIABLE_LENGTH_CONTENT_AS_CHUNKS, READ_FIXED_LENGTH_CONTENT, READ_FIXED_LENGTH_CONTENT_AS_CHUNKS, READ_CHUNK_SIZE, READ_CHUNKED_CONTENT, READ_CHUNKED_CONTENT_AS_CHUNKS, READ_CHUNK_DELIMITER, READ_CHUNK_FOOTER } /** * Creates a new instance with the default * {@code maxInitialLineLength (4096}}, {@code maxHeaderSize (8192)}, and * {@code maxChunkSize (8192)}. */ protected HttpMessageDecoder() { this(4096, 8192, 8192); } /** * Creates a new instance with the specified parameters. */ protected HttpMessageDecoder( int maxInitialLineLength, int maxHeaderSize, int maxChunkSize) { super(State.SKIP_CONTROL_CHARS, true); if (maxInitialLineLength <= 0) { throw new IllegalArgumentException( "maxInitialLineLength must be a positive integer: " + maxInitialLineLength); } if (maxHeaderSize <= 0) { throw new IllegalArgumentException( "maxHeaderSize must be a positive integer: " + maxHeaderSize); } if (maxChunkSize < 0) { throw new IllegalArgumentException( "maxChunkSize must be a positive integer: " + maxChunkSize); } this.maxInitialLineLength = maxInitialLineLength; this.maxHeaderSize = maxHeaderSize; this.maxChunkSize = maxChunkSize; } @Override protected Object decode( ChannelHandlerContext ctx, Channel channel, ChannelBuffer buffer, State state) throws Exception { switch (state) { case SKIP_CONTROL_CHARS: { try { skipControlCharacters(buffer); checkpoint(State.READ_INITIAL); } finally { checkpoint(); } } case READ_INITIAL: { String[] initialLine = splitInitialLine(readLine(buffer, maxInitialLineLength)); if (initialLine.length < 3) { // Invalid initial line - ignore. checkpoint(State.SKIP_CONTROL_CHARS); return null; } message = createMessage(initialLine); checkpoint(State.READ_HEADER); } case READ_HEADER: { State nextState = readHeaders(buffer); checkpoint(nextState); if (nextState == State.READ_CHUNK_SIZE) { // Chunked encoding message.setChunked(true); // Generate HttpMessage first. HttpChunks will follow. return message; } if (nextState == State.SKIP_CONTROL_CHARS) { // No content is expected. // Remove the headers which are not supposed to be present not // to confuse subsequent handlers. message.removeHeader(HttpHeaders.Names.TRANSFER_ENCODING); return message; } long contentLength = HttpHeaders.getContentLength(message, -1); if (contentLength == 0 || contentLength == -1 && isDecodingRequest()) { content = ChannelBuffers.EMPTY_BUFFER; return reset(); } switch (nextState) { case READ_FIXED_LENGTH_CONTENT: if (contentLength > maxChunkSize || HttpHeaders.is100ContinueExpected(message)) { // Generate HttpMessage first. HttpChunks will follow. checkpoint(State.READ_FIXED_LENGTH_CONTENT_AS_CHUNKS); message.setChunked(true); // chunkSize will be decreased as the READ_FIXED_LENGTH_CONTENT_AS_CHUNKS // state reads data chunk by chunk. chunkSize = HttpHeaders.getContentLength(message, -1); return message; } break; case READ_VARIABLE_LENGTH_CONTENT: if (buffer.readableBytes() > maxChunkSize || HttpHeaders.is100ContinueExpected(message)) { // Generate HttpMessage first. HttpChunks will follow. checkpoint(State.READ_VARIABLE_LENGTH_CONTENT_AS_CHUNKS); message.setChunked(true); return message; } break; default: throw new IllegalStateException("Unexpected state: " + nextState); } // We return null here, this forces decode to be called again where we will decode the content return null; } case READ_VARIABLE_LENGTH_CONTENT: { int toRead = actualReadableBytes(); if (toRead > maxChunkSize) { toRead = maxChunkSize; } if (!message.isChunked()) { message.setChunked(true); return new Object[] {message, new DefaultHttpChunk(buffer.readBytes(toRead))}; } else { return new DefaultHttpChunk(buffer.readBytes(toRead)); } } case READ_VARIABLE_LENGTH_CONTENT_AS_CHUNKS: { // Keep reading data as a chunk until the end of connection is reached. int toRead = actualReadableBytes(); if (toRead > maxChunkSize) { toRead = maxChunkSize; } HttpChunk chunk = new DefaultHttpChunk(buffer.readBytes(toRead)); if (!buffer.readable()) { // Reached to the end of the connection. reset(); if (!chunk.isLast()) { // Append the last chunk. return new Object[] { chunk, HttpChunk.LAST_CHUNK }; } } return chunk; } case READ_FIXED_LENGTH_CONTENT: { return readFixedLengthContent(buffer); } case READ_FIXED_LENGTH_CONTENT_AS_CHUNKS: { long chunkSize = this.chunkSize; int readLimit = actualReadableBytes(); // Check if the buffer is readable first as we use the readable byte count // to create the HttpChunk. This is needed as otherwise we may end up with // create a HttpChunk instance that contains an empty buffer and so is // handled like it is the last HttpChunk. // // See https://github.com/netty/netty/issues/433 if (readLimit == 0) { return null; } int toRead = readLimit; if (toRead > maxChunkSize) { toRead = maxChunkSize; } if (toRead > chunkSize) { toRead = (int) chunkSize; } HttpChunk chunk = new DefaultHttpChunk(buffer.readBytes(toRead)); if (chunkSize > toRead) { chunkSize -= toRead; } else { chunkSize = 0; } this.chunkSize = chunkSize; if (chunkSize == 0) { // Read all content. reset(); if (!chunk.isLast()) { // Append the last chunk. return new Object[] { chunk, HttpChunk.LAST_CHUNK }; } } return chunk; } /** * everything else after this point takes care of reading chunked content. basically, read chunk size, * read chunk, read and ignore the CRLF and repeat until 0 */ case READ_CHUNK_SIZE: { String line = readLine(buffer, maxInitialLineLength); int chunkSize = getChunkSize(line); this.chunkSize = chunkSize; if (chunkSize == 0) { checkpoint(State.READ_CHUNK_FOOTER); return null; } else if (chunkSize > maxChunkSize) { // A chunk is too large. Split them into multiple chunks again. checkpoint(State.READ_CHUNKED_CONTENT_AS_CHUNKS); } else { checkpoint(State.READ_CHUNKED_CONTENT); } } case READ_CHUNKED_CONTENT: { assert chunkSize <= Integer.MAX_VALUE; HttpChunk chunk = new DefaultHttpChunk(buffer.readBytes((int) chunkSize)); checkpoint(State.READ_CHUNK_DELIMITER); return chunk; } case READ_CHUNKED_CONTENT_AS_CHUNKS: { assert chunkSize <= Integer.MAX_VALUE; int chunkSize = (int) this.chunkSize; int readLimit = actualReadableBytes(); // Check if the buffer is readable first as we use the readable byte count // to create the HttpChunk. This is needed as otherwise we may end up with // create a HttpChunk instance that contains an empty buffer and so is // handled like it is the last HttpChunk. // // See https://github.com/netty/netty/issues/433 if (readLimit == 0) { return null; } int toRead = chunkSize; if (toRead > maxChunkSize) { toRead = maxChunkSize; } if (toRead > readLimit) { toRead = readLimit; } HttpChunk chunk = new DefaultHttpChunk(buffer.readBytes(toRead)); if (chunkSize > toRead) { chunkSize -= toRead; } else { chunkSize = 0; } this.chunkSize = chunkSize; if (chunkSize == 0) { // Read all content. checkpoint(State.READ_CHUNK_DELIMITER); } if (!chunk.isLast()) { return chunk; } } case READ_CHUNK_DELIMITER: { for (;;) { byte next = buffer.readByte(); if (next == HttpConstants.CR) { if (buffer.readByte() == HttpConstants.LF) { checkpoint(State.READ_CHUNK_SIZE); return null; } } else if (next == HttpConstants.LF) { checkpoint(State.READ_CHUNK_SIZE); return null; } } } case READ_CHUNK_FOOTER: { HttpChunkTrailer trailer = readTrailingHeaders(buffer); if (maxChunkSize == 0) { // Chunked encoding disabled. return reset(); } else { reset(); // The last chunk, which is empty return trailer; } } default: { throw new Error("Shouldn't reach here."); } } } protected boolean isContentAlwaysEmpty(HttpMessage msg) { if (msg instanceof HttpResponse) { HttpResponse res = (HttpResponse) msg; int code = res.getStatus().getCode(); // Correctly handle return codes of 1xx. // // See: // - http://www.w3.org/Protocols/rfc2616/rfc2616-sec4.html Section 4.4 // - https://github.com/netty/netty/issues/222 if (code >= 100 && code < 200) { if (code == 101 && !res.containsHeader(HttpHeaders.Names.SEC_WEBSOCKET_ACCEPT)) { // It's Hixie 76 websocket handshake response return false; } return true; } switch (code) { case 204: case 205: case 304: return true; } } return false; } private Object reset() { HttpMessage message = this.message; ChannelBuffer content = this.content; if (content != null) { message.setContent(content); this.content = null; } this.message = null; checkpoint(State.SKIP_CONTROL_CHARS); return message; } private static void skipControlCharacters(ChannelBuffer buffer) { for (;;) { char c = (char) buffer.readUnsignedByte(); if (!Character.isISOControl(c) && !Character.isWhitespace(c)) { buffer.readerIndex(buffer.readerIndex() - 1); break; } } } private Object readFixedLengthContent(ChannelBuffer buffer) { //we have a content-length so we just read the correct number of bytes long length = HttpHeaders.getContentLength(message, -1); assert length <= Integer.MAX_VALUE; int toRead = (int) length - contentRead; if (toRead > actualReadableBytes()) { toRead = actualReadableBytes(); } contentRead += toRead; if (length < contentRead) { if (!message.isChunked()) { message.setChunked(true); return new Object[] {message, new DefaultHttpChunk(buffer.readBytes(toRead))}; } else { return new DefaultHttpChunk(buffer.readBytes(toRead)); } } if (content == null) { content = buffer.readBytes((int) length); } else { content.writeBytes(buffer, (int) length); } return reset(); } private State readHeaders(ChannelBuffer buffer) throws TooLongFrameException { headerSize = 0; final HttpMessage message = this.message; String line = readHeader(buffer); String name = null; String value = null; if (line.length() != 0) { message.clearHeaders(); do { char firstChar = line.charAt(0); if (name != null && (firstChar == ' ' || firstChar == '\t')) { value = value + ' ' + line.trim(); } else { if (name != null) { message.addHeader(name, value); } String[] header = splitHeader(line); name = header[0]; value = header[1]; } line = readHeader(buffer); } while (line.length() != 0); // Add the last header. if (name != null) { message.addHeader(name, value); } } State nextState; if (isContentAlwaysEmpty(message)) { nextState = State.SKIP_CONTROL_CHARS; } else if (message.isChunked()) { // HttpMessage.isChunked() returns true when either: // 1) HttpMessage.setChunked(true) was called or // 2) 'Transfer-Encoding' is 'chunked'. // Because this decoder did not call HttpMessage.setChunked(true) // yet, HttpMessage.isChunked() should return true only when // 'Transfer-Encoding' is 'chunked'. nextState = State.READ_CHUNK_SIZE; } else if (HttpHeaders.getContentLength(message, -1) >= 0) { nextState = State.READ_FIXED_LENGTH_CONTENT; } else { nextState = State.READ_VARIABLE_LENGTH_CONTENT; } return nextState; } private HttpChunkTrailer readTrailingHeaders(ChannelBuffer buffer) throws TooLongFrameException { headerSize = 0; String line = readHeader(buffer); String lastHeader = null; if (line.length() != 0) { HttpChunkTrailer trailer = new DefaultHttpChunkTrailer(); do { char firstChar = line.charAt(0); if (lastHeader != null && (firstChar == ' ' || firstChar == '\t')) { List current = trailer.getHeaders(lastHeader); if (!current.isEmpty()) { int lastPos = current.size() - 1; String newString = current.get(lastPos) + line.trim(); current.set(lastPos, newString); } else { // Content-Length, Transfer-Encoding, or Trailer } } else { String[] header = splitHeader(line); String name = header[0]; if (!name.equalsIgnoreCase(HttpHeaders.Names.CONTENT_LENGTH) && !name.equalsIgnoreCase(HttpHeaders.Names.TRANSFER_ENCODING) && !name.equalsIgnoreCase(HttpHeaders.Names.TRAILER)) { trailer.addHeader(name, header[1]); } lastHeader = name; } line = readHeader(buffer); } while (line.length() != 0); return trailer; } return HttpChunk.LAST_CHUNK; } private String readHeader(ChannelBuffer buffer) throws TooLongFrameException { StringBuilder sb = new StringBuilder(64); int headerSize = this.headerSize; loop: for (;;) { char nextByte = (char) buffer.readByte(); headerSize ++; switch (nextByte) { case HttpConstants.CR: nextByte = (char) buffer.readByte(); headerSize ++; if (nextByte == HttpConstants.LF) { break loop; } break; case HttpConstants.LF: break loop; } // Abort decoding if the header part is too large. if (headerSize >= maxHeaderSize) { // TODO: Respond with Bad Request and discard the traffic // or close the connection. // No need to notify the upstream handlers - just log. // If decoding a response, just throw an exception. throw new TooLongFrameException( "HTTP header is larger than " + maxHeaderSize + " bytes."); } sb.append(nextByte); } this.headerSize = headerSize; return sb.toString(); } protected abstract boolean isDecodingRequest(); protected abstract HttpMessage createMessage(String[] initialLine) throws Exception; private static int getChunkSize(String hex) { hex = hex.trim(); for (int i = 0; i < hex.length(); i ++) { char c = hex.charAt(i); if (c == ';' || Character.isWhitespace(c) || Character.isISOControl(c)) { hex = hex.substring(0, i); break; } } return Integer.parseInt(hex, 16); } private static String readLine(ChannelBuffer buffer, int maxLineLength) throws TooLongFrameException { StringBuilder sb = new StringBuilder(64); int lineLength = 0; while (true) { byte nextByte = buffer.readByte(); if (nextByte == HttpConstants.CR) { nextByte = buffer.readByte(); if (nextByte == HttpConstants.LF) { return sb.toString(); } } else if (nextByte == HttpConstants.LF) { return sb.toString(); } else { if (lineLength >= maxLineLength) { // TODO: Respond with Bad Request and discard the traffic // or close the connection. // No need to notify the upstream handlers - just log. // If decoding a response, just throw an exception. throw new TooLongFrameException( "An HTTP line is larger than " + maxLineLength + " bytes."); } lineLength ++; sb.append((char) nextByte); } } } private static String[] splitInitialLine(String sb) { int aStart; int aEnd; int bStart; int bEnd; int cStart; int cEnd; aStart = findNonWhitespace(sb, 0); aEnd = findWhitespace(sb, aStart); bStart = findNonWhitespace(sb, aEnd); bEnd = findWhitespace(sb, bStart); cStart = findNonWhitespace(sb, bEnd); cEnd = findEndOfString(sb); return new String[] { sb.substring(aStart, aEnd), sb.substring(bStart, bEnd), cStart < cEnd? sb.substring(cStart, cEnd) : "" }; } private static String[] splitHeader(String sb) { final int length = sb.length(); int nameStart; int nameEnd; int colonEnd; int valueStart; int valueEnd; nameStart = findNonWhitespace(sb, 0); for (nameEnd = nameStart; nameEnd < length; nameEnd ++) { char ch = sb.charAt(nameEnd); if (ch == ':' || Character.isWhitespace(ch)) { break; } } for (colonEnd = nameEnd; colonEnd < length; colonEnd ++) { if (sb.charAt(colonEnd) == ':') { colonEnd ++; break; } } valueStart = findNonWhitespace(sb, colonEnd); if (valueStart == length) { return new String[] { sb.substring(nameStart, nameEnd), "" }; } valueEnd = findEndOfString(sb); return new String[] { sb.substring(nameStart, nameEnd), sb.substring(valueStart, valueEnd) }; } private static int findNonWhitespace(String sb, int offset) { int result; for (result = offset; result < sb.length(); result ++) { if (!Character.isWhitespace(sb.charAt(result))) { break; } } return result; } private static int findWhitespace(String sb, int offset) { int result; for (result = offset; result < sb.length(); result ++) { if (Character.isWhitespace(sb.charAt(result))) { break; } } return result; } private static int findEndOfString(String sb) { int result; for (result = sb.length(); result > 0; result --) { if (!Character.isWhitespace(sb.charAt(result - 1))) { break; } } return result; } }




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