/*
* 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 io.netty.handler.codec.http;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.ByteBufProcessor;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPipeline;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.handler.codec.DecoderResult;
import io.netty.handler.codec.TooLongFrameException;
import io.netty.util.internal.AppendableCharSequence;
import java.util.List;
/**
* Decodes {@link ByteBuf}s into {@link HttpMessage}s and
* {@link HttpContent}s.
*
* <h3>Parameters that prevents excessive memory consumption</h3>
* <table border="1">
* <tr>
* <th>Name</th><th>Meaning</th>
* </tr>
* <tr>
* <td>{@code maxInitialLineLength}</td>
* <td>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.</td>
* </tr>
* <tr>
* <td>{@code maxHeaderSize}</td>
* <td>The maximum length of all headers. If the sum of the length of each
* header exceeds this value, a {@link TooLongFrameException} will be raised.</td>
* </tr>
* <tr>
* <td>{@code maxChunkSize}</td>
* <td>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 HttpContent}s whose length is
* {@code maxChunkSize} at maximum.</td>
* </tr>
* </table>
*
* <h3>Chunked Content</h3>
*
* 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 HttpContent}s per single HTTP message to avoid excessive memory
* consumption. For example, the following HTTP message:
* <pre>
* GET / HTTP/1.1
* Transfer-Encoding: chunked
*
* 1a
* abcdefghijklmnopqrstuvwxyz
* 10
* 1234567890abcdef
* 0
* Content-MD5: ...
* <i>[blank line]</i>
* </pre>
* triggers {@link HttpRequestDecoder} to generate 3 objects:
* <ol>
* <li>An {@link HttpRequest},</li>
* <li>The first {@link HttpContent} whose content is {@code 'abcdefghijklmnopqrstuvwxyz'},</li>
* <li>The second {@link LastHttpContent} whose content is {@code '1234567890abcdef'}, which marks
* the end of the content.</li>
* </ol>
*
* If you prefer not to handle {@link HttpContent}s by yourself for your
* convenience, insert {@link HttpObjectAggregator} after this decoder in the
* {@link ChannelPipeline}. However, please note that your server might not
* be as memory efficient as without the aggregator.
*
* <h3>Extensibility</h3>
*
* Please note that this decoder is designed to be extended to implement
* a protocol derived from HTTP, such as
* <a href="http://en.wikipedia.org/wiki/Real_Time_Streaming_Protocol">RTSP</a> and
* <a href="http://en.wikipedia.org/wiki/Internet_Content_Adaptation_Protocol">ICAP</a>.
* To implement the decoder of such a derived protocol, extend this class and
* implement all abstract methods properly.
*/
public abstract class HttpObjectDecoder extends ByteToMessageDecoder {
private static final String EMPTY_VALUE = "";
private final int maxChunkSize;
private final boolean chunkedSupported;
protected final boolean validateHeaders;
private final HeaderParser headerParser;
private final LineParser lineParser;
private HttpMessage message;
private long chunkSize;
private long contentLength = Long.MIN_VALUE;
private volatile boolean resetRequested;
// These will be updated by splitHeader(...)
private CharSequence name;
private CharSequence value;
private LastHttpContent trailer;
/**
* The internal state of {@link HttpObjectDecoder}.
* <em>Internal use only</em>.
*/
private enum State {
SKIP_CONTROL_CHARS,
READ_INITIAL,
READ_HEADER,
READ_VARIABLE_LENGTH_CONTENT,
READ_FIXED_LENGTH_CONTENT,
READ_CHUNK_SIZE,
READ_CHUNKED_CONTENT,
READ_CHUNK_DELIMITER,
READ_CHUNK_FOOTER,
BAD_MESSAGE,
UPGRADED
}
private State currentState = State.SKIP_CONTROL_CHARS;
/**
* Creates a new instance with the default
* {@code maxInitialLineLength (4096}}, {@code maxHeaderSize (8192)}, and
* {@code maxChunkSize (8192)}.
*/
protected HttpObjectDecoder() {
this(4096, 8192, 8192, true);
}
/**
* Creates a new instance with the specified parameters.
*/
protected HttpObjectDecoder(
int maxInitialLineLength, int maxHeaderSize, int maxChunkSize, boolean chunkedSupported) {
this(maxInitialLineLength, maxHeaderSize, maxChunkSize, chunkedSupported, true);
}
/**
* Creates a new instance with the specified parameters.
*/
protected HttpObjectDecoder(
int maxInitialLineLength, int maxHeaderSize, int maxChunkSize,
boolean chunkedSupported, boolean validateHeaders) {
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.maxChunkSize = maxChunkSize;
this.chunkedSupported = chunkedSupported;
this.validateHeaders = validateHeaders;
AppendableCharSequence seq = new AppendableCharSequence(128);
lineParser = new LineParser(seq, maxInitialLineLength);
headerParser = new HeaderParser(seq, maxHeaderSize);
}
@Override
protected void decode(ChannelHandlerContext ctx, ByteBuf buffer, List<Object> out) throws Exception {
if (resetRequested) {
resetNow();
}
switch (currentState) {
case SKIP_CONTROL_CHARS: {
if (!skipControlCharacters(buffer)) {
return;
}
currentState = State.READ_INITIAL;
}
case READ_INITIAL: try {
AppendableCharSequence line = lineParser.parse(buffer);
if (line == null) {
return;
}
String[] initialLine = splitInitialLine(line);
if (initialLine.length < 3) {
// Invalid initial line - ignore.
currentState = State.SKIP_CONTROL_CHARS;
return;
}
message = createMessage(initialLine);
currentState = State.READ_HEADER;
// fall-through
} catch (Exception e) {
out.add(invalidMessage(buffer, e));
return;
}
case READ_HEADER: try {
State nextState = readHeaders(buffer);
if (nextState == null) {
return;
}
currentState = nextState;
switch (nextState) {
case SKIP_CONTROL_CHARS:
// fast-path
// No content is expected.
out.add(message);
out.add(LastHttpContent.EMPTY_LAST_CONTENT);
resetNow();
return;
case READ_CHUNK_SIZE:
if (!chunkedSupported) {
throw new IllegalArgumentException("Chunked messages not supported");
}
// Chunked encoding - generate HttpMessage first. HttpChunks will follow.
out.add(message);
return;
default:
long contentLength = contentLength();
if (contentLength == 0 || contentLength == -1 && isDecodingRequest()) {
out.add(message);
out.add(LastHttpContent.EMPTY_LAST_CONTENT);
resetNow();
return;
}
assert nextState == State.READ_FIXED_LENGTH_CONTENT ||
nextState == State.READ_VARIABLE_LENGTH_CONTENT;
out.add(message);
if (nextState == State.READ_FIXED_LENGTH_CONTENT) {
// chunkSize will be decreased as the READ_FIXED_LENGTH_CONTENT state reads data chunk by
// chunk.
chunkSize = contentLength;
}
// We return here, this forces decode to be called again where we will decode the content
return;
}
} catch (Exception e) {
out.add(invalidMessage(buffer, e));
return;
}
case READ_VARIABLE_LENGTH_CONTENT: {
// Keep reading data as a chunk until the end of connection is reached.
int toRead = Math.min(buffer.readableBytes(), maxChunkSize);
if (toRead > 0) {
ByteBuf content = buffer.readSlice(toRead).retain();
out.add(new DefaultHttpContent(content));
}
return;
}
case READ_FIXED_LENGTH_CONTENT: {
int readLimit = buffer.readableBytes();
// 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;
}
int toRead = Math.min(readLimit, maxChunkSize);
if (toRead > chunkSize) {
toRead = (int) chunkSize;
}
ByteBuf content = buffer.readSlice(toRead).retain();
chunkSize -= toRead;
if (chunkSize == 0) {
// Read all content.
out.add(new DefaultLastHttpContent(content, validateHeaders));
resetNow();
} else {
out.add(new DefaultHttpContent(content));
}
return;
}
/**
* 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: try {
AppendableCharSequence line = lineParser.parse(buffer);
if (line == null) {
return;
}
int chunkSize = getChunkSize(line.toString());
this.chunkSize = chunkSize;
if (chunkSize == 0) {
currentState = State.READ_CHUNK_FOOTER;
return;
}
currentState = State.READ_CHUNKED_CONTENT;
// fall-through
} catch (Exception e) {
out.add(invalidChunk(buffer, e));
return;
}
case READ_CHUNKED_CONTENT: {
assert chunkSize <= Integer.MAX_VALUE;
int toRead = Math.min((int) chunkSize, maxChunkSize);
toRead = Math.min(toRead, buffer.readableBytes());
if (toRead == 0) {
return;
}
HttpContent chunk = new DefaultHttpContent(buffer.readSlice(toRead).retain());
chunkSize -= toRead;
out.add(chunk);
if (chunkSize != 0) {
return;
}
currentState = State.READ_CHUNK_DELIMITER;
// fall-through
}
case READ_CHUNK_DELIMITER: {
final int wIdx = buffer.writerIndex();
int rIdx = buffer.readerIndex();
while (wIdx > rIdx) {
byte next = buffer.getByte(rIdx++);
if (next == HttpConstants.LF) {
currentState = State.READ_CHUNK_SIZE;
break;
}
}
buffer.readerIndex(rIdx);
return;
}
case READ_CHUNK_FOOTER: try {
LastHttpContent trailer = readTrailingHeaders(buffer);
if (trailer == null) {
return;
}
out.add(trailer);
resetNow();
return;
} catch (Exception e) {
out.add(invalidChunk(buffer, e));
return;
}
case BAD_MESSAGE: {
// Keep discarding until disconnection.
buffer.skipBytes(buffer.readableBytes());
break;
}
case UPGRADED: {
int readableBytes = buffer.readableBytes();
if (readableBytes > 0) {
// Keep on consuming as otherwise we may trigger an DecoderException,
// other handler will replace this codec with the upgraded protocol codec to
// take the traffic over at some point then.
// See https://github.com/netty/netty/issues/2173
out.add(buffer.readBytes(readableBytes));
}
break;
}
}
}
@Override
protected void decodeLast(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
decode(ctx, in, out);
// Handle the last unfinished message.
if (message != null) {
boolean chunked = HttpHeaders.isTransferEncodingChunked(message);
if (currentState == State.READ_VARIABLE_LENGTH_CONTENT && !in.isReadable() && !chunked) {
// End of connection.
out.add(LastHttpContent.EMPTY_LAST_CONTENT);
reset();
return;
}
// Check if the closure of the connection signifies the end of the content.
boolean prematureClosure;
if (isDecodingRequest() || chunked) {
// The last request did not wait for a response.
prematureClosure = true;
} else {
// Compare the length of the received content and the 'Content-Length' header.
// If the 'Content-Length' header is absent, the length of the content is determined by the end of the
// connection, so it is perfectly fine.
prematureClosure = contentLength() > 0;
}
resetNow();
if (!prematureClosure) {
out.add(LastHttpContent.EMPTY_LAST_CONTENT);
}
}
}
protected boolean isContentAlwaysEmpty(HttpMessage msg) {
if (msg instanceof HttpResponse) {
HttpResponse res = (HttpResponse) msg;
int code = res.getStatus().code();
// 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) {
// One exception: Hixie 76 websocket handshake response
return !(code == 101 && !res.headers().contains(HttpHeaders.Names.SEC_WEBSOCKET_ACCEPT));
}
switch (code) {
case 204: case 205: case 304:
return true;
}
}
return false;
}
/**
* Resets the state of the decoder so that it is ready to decode a new message.
* This method is useful for handling a rejected request with {@code Expect: 100-continue} header.
*/
public void reset() {
resetRequested = true;
}
private void resetNow() {
HttpMessage message = this.message;
this.message = null;
name = null;
value = null;
contentLength = Long.MIN_VALUE;
lineParser.reset();
headerParser.reset();
trailer = null;
if (!isDecodingRequest()) {
HttpResponse res = (HttpResponse) message;
if (res != null && res.getStatus().code() == 101) {
currentState = State.UPGRADED;
return;
}
}
currentState = State.SKIP_CONTROL_CHARS;
}
private HttpMessage invalidMessage(ByteBuf in, Exception cause) {
currentState = State.BAD_MESSAGE;
// Advance the readerIndex so that ByteToMessageDecoder does not complain
// when we produced an invalid message without consuming anything.
in.skipBytes(in.readableBytes());
if (message != null) {
message.setDecoderResult(DecoderResult.failure(cause));
} else {
message = createInvalidMessage();
message.setDecoderResult(DecoderResult.failure(cause));
}
HttpMessage ret = message;
message = null;
return ret;
}
private HttpContent invalidChunk(ByteBuf in, Exception cause) {
currentState = State.BAD_MESSAGE;
// Advance the readerIndex so that ByteToMessageDecoder does not complain
// when we produced an invalid message without consuming anything.
in.skipBytes(in.readableBytes());
HttpContent chunk = new DefaultLastHttpContent(Unpooled.EMPTY_BUFFER);
chunk.setDecoderResult(DecoderResult.failure(cause));
message = null;
trailer = null;
return chunk;
}
private static boolean skipControlCharacters(ByteBuf buffer) {
boolean skiped = false;
final int wIdx = buffer.writerIndex();
int rIdx = buffer.readerIndex();
while (wIdx > rIdx) {
int c = buffer.getUnsignedByte(rIdx++);
if (!Character.isISOControl(c) && !Character.isWhitespace(c)) {
rIdx--;
skiped = true;
break;
}
}
buffer.readerIndex(rIdx);
return skiped;
}
private State readHeaders(ByteBuf buffer) {
final HttpMessage message = this.message;
final HttpHeaders headers = message.headers();
AppendableCharSequence line = headerParser.parse(buffer);
if (line == null) {
return null;
}
if (line.length() > 0) {
do {
char firstChar = line.charAt(0);
if (name != null && (firstChar == ' ' || firstChar == '\t')) {
StringBuilder buf = new StringBuilder(value.length() + line.length() + 1);
buf.append(value)
.append(' ')
.append(line.toString().trim());
value = buf.toString();
} else {
if (name != null) {
headers.add(name, value);
}
splitHeader(line);
}
line = headerParser.parse(buffer);
if (line == null) {
return null;
}
} while (line.length() > 0);
}
// Add the last header.
if (name != null) {
headers.add(name, value);
}
// reset name and value fields
name = null;
value = null;
State nextState;
if (isContentAlwaysEmpty(message)) {
HttpHeaders.removeTransferEncodingChunked(message);
nextState = State.SKIP_CONTROL_CHARS;
} else if (HttpHeaders.isTransferEncodingChunked(message)) {
nextState = State.READ_CHUNK_SIZE;
} else if (contentLength() >= 0) {
nextState = State.READ_FIXED_LENGTH_CONTENT;
} else {
nextState = State.READ_VARIABLE_LENGTH_CONTENT;
}
return nextState;
}
private long contentLength() {
if (contentLength == Long.MIN_VALUE) {
contentLength = HttpHeaders.getContentLength(message, -1);
}
return contentLength;
}
private LastHttpContent readTrailingHeaders(ByteBuf buffer) {
AppendableCharSequence line = headerParser.parse(buffer);
if (line == null) {
return null;
}
CharSequence lastHeader = null;
if (line.length() > 0) {
LastHttpContent trailer = this.trailer;
if (trailer == null) {
trailer = this.trailer = new DefaultLastHttpContent(Unpooled.EMPTY_BUFFER, validateHeaders);
}
do {
char firstChar = line.charAt(0);
if (lastHeader != null && (firstChar == ' ' || firstChar == '\t')) {
List<String> current = trailer.trailingHeaders().getAll(lastHeader);
if (!current.isEmpty()) {
int lastPos = current.size() - 1;
String lineTrimmed = line.toString().trim();
CharSequence currentLastPos = current.get(lastPos);
StringBuilder b = new StringBuilder(currentLastPos.length() + lineTrimmed.length());
b.append(currentLastPos)
.append(lineTrimmed);
current.set(lastPos, b.toString());
} else {
// Content-Length, Transfer-Encoding, or Trailer
}
} else {
splitHeader(line);
CharSequence headerName = name;
if (!HttpHeaders.equalsIgnoreCase(HttpHeaders.Names.CONTENT_LENGTH, headerName) &&
!HttpHeaders.equalsIgnoreCase(HttpHeaders.Names.TRANSFER_ENCODING, headerName) &&
!HttpHeaders.equalsIgnoreCase(HttpHeaders.Names.TRAILER, headerName)) {
trailer.trailingHeaders().add(headerName, value);
}
lastHeader = name;
// reset name and value fields
name = null;
value = null;
}
line = headerParser.parse(buffer);
if (line == null) {
return null;
}
} while (line.length() > 0);
this.trailer = null;
return trailer;
}
return LastHttpContent.EMPTY_LAST_CONTENT;
}
protected abstract boolean isDecodingRequest();
protected abstract HttpMessage createMessage(String[] initialLine) throws Exception;
protected abstract HttpMessage createInvalidMessage();
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[] splitInitialLine(AppendableCharSequence 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 void splitHeader(AppendableCharSequence 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;
}
}
name = sb.substring(nameStart, nameEnd);
valueStart = findNonWhitespace(sb, colonEnd);
if (valueStart == length) {
value = EMPTY_VALUE;
} else {
valueEnd = findEndOfString(sb);
value = sb.substring(valueStart, valueEnd);
}
}
private static int findNonWhitespace(CharSequence 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(CharSequence 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(CharSequence sb) {
int result;
for (result = sb.length(); result > 0; result --) {
if (!Character.isWhitespace(sb.charAt(result - 1))) {
break;
}
}
return result;
}
private static class HeaderParser implements ByteBufProcessor {
private final AppendableCharSequence seq;
private final int maxLength;
private int size;
HeaderParser(AppendableCharSequence seq, int maxLength) {
this.seq = seq;
this.maxLength = maxLength;
}
public AppendableCharSequence parse(ByteBuf buffer) {
final int oldSize = size;
seq.reset();
int i = buffer.forEachByte(this);
if (i == -1) {
size = oldSize;
return null;
}
buffer.readerIndex(i + 1);
return seq;
}
public void reset() {
size = 0;
}
@Override
public boolean process(byte value) throws Exception {
char nextByte = (char) value;
if (nextByte == HttpConstants.CR) {
return true;
}
if (nextByte == HttpConstants.LF) {
return false;
}
if (++ size > maxLength) {
// 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 newException(maxLength);
}
seq.append(nextByte);
return true;
}
protected TooLongFrameException newException(int maxLength) {
return new TooLongFrameException("HTTP header is larger than " + maxLength + " bytes.");
}
}
private static final class LineParser extends HeaderParser {
LineParser(AppendableCharSequence seq, int maxLength) {
super(seq, maxLength);
}
@Override
public AppendableCharSequence parse(ByteBuf buffer) {
reset();
return super.parse(buffer);
}
@Override
protected TooLongFrameException newException(int maxLength) {
return new TooLongFrameException("An HTTP line is larger than " + maxLength + " bytes.");
}
}
}