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/*
* Copyright 2011 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 io.netty.handler.codec.http;
import java.util.List;
import io.netty.buffer.ChannelBuffer;
import io.netty.buffer.ChannelBuffers;
import io.netty.channel.Channel;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.frame.TooLongFrameException;
import io.netty.handler.codec.replay.ReplayingDecoder;
/**
* Decodes {@link ChannelBuffer}s into {@link HttpMessage}s and
* {@link HttpChunk}s.
*
*
Parameters that prevents excessive memory consumption
*
*
*
Name
Meaning
*
*
*
{@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:
*
* triggers {@link HttpRequestDecoder} to generate 4 objects:
*
*
An {@link HttpRequest} whose {@link HttpMessage#isChunked() chunked}
* property is {@code true},
*
The first {@link HttpChunk} whose content is {@code 'abcdefghijklmnopqrstuvwxyz'},
*
The second {@link HttpChunk} whose content is {@code '1234567890abcdef'}, and
*
An {@link HttpChunkTrailer} which marks the end of the content.
*
*
* 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;
/**
* 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;
} else 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;
} else {
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: {
if (content == null) {
content = ChannelBuffers.dynamicBuffer(channel.getConfig().getBufferFactory());
}
//this will cause a replay error until the channel is closed where this will read what's left in the buffer
content.writeBytes(buffer.readBytes(buffer.readableBytes()));
return reset();
}
case READ_VARIABLE_LENGTH_CONTENT_AS_CHUNKS: {
// Keep reading data as a chunk until the end of connection is reached.
int chunkSize = Math.min(maxChunkSize, buffer.readableBytes());
HttpChunk chunk = new DefaultHttpChunk(buffer.readBytes(chunkSize));
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: {
//we have a content-length so we just read the correct number of bytes
readFixedLengthContent(buffer);
return reset();
}
case READ_FIXED_LENGTH_CONTENT_AS_CHUNKS: {
long chunkSize = this.chunkSize;
HttpChunk chunk;
if (chunkSize > maxChunkSize) {
chunk = new DefaultHttpChunk(buffer.readBytes(maxChunkSize));
chunkSize -= maxChunkSize;
} else {
assert chunkSize <= Integer.MAX_VALUE;
chunk = new DefaultHttpChunk(buffer.readBytes((int) chunkSize));
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: {
long chunkSize = this.chunkSize;
HttpChunk chunk;
if (chunkSize > maxChunkSize) {
chunk = new DefaultHttpChunk(buffer.readBytes(maxChunkSize));
chunkSize -= maxChunkSize;
} else {
assert chunkSize <= Integer.MAX_VALUE;
chunk = new DefaultHttpChunk(buffer.readBytes((int) chunkSize));
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 == HttpCodecUtil.CR) {
if (buffer.readByte() == HttpCodecUtil.LF) {
checkpoint(State.READ_CHUNK_SIZE);
return null;
}
} else if (next == HttpCodecUtil.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();
if (code < 200) {
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 void skipControlCharacters(ChannelBuffer buffer) {
for (;;) {
char c = (char) buffer.readUnsignedByte();
if (!Character.isISOControl(c) &&
!Character.isWhitespace(c)) {
buffer.readerIndex(buffer.readerIndex() - 1);
break;
}
}
}
private void readFixedLengthContent(ChannelBuffer buffer) {
long length = HttpHeaders.getContentLength(message, -1);
assert length <= Integer.MAX_VALUE;
if (content == null) {
content = buffer.readBytes((int) length);
} else {
content.writeBytes(buffer.readBytes((int) length));
}
}
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.size() != 0) {
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 HttpCodecUtil.CR:
nextByte = (char) buffer.readByte();
headerSize ++;
if (nextByte == HttpCodecUtil.LF) {
break loop;
}
break;
case HttpCodecUtil.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 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 String readLine(ChannelBuffer buffer, int maxLineLength) throws TooLongFrameException {
StringBuilder sb = new StringBuilder(64);
int lineLength = 0;
while (true) {
byte nextByte = buffer.readByte();
if (nextByte == HttpCodecUtil.CR) {
nextByte = buffer.readByte();
if (nextByte == HttpCodecUtil.LF) {
return sb.toString();
}
} else if (nextByte == HttpCodecUtil.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 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 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 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 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 int findEndOfString(String sb) {
int result;
for (result = sb.length(); result > 0; result --) {
if (!Character.isWhitespace(sb.charAt(result - 1))) {
break;
}
}
return result;
}
}
