/*
* Copyright 2014 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.haproxy;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.handler.codec.ByteToMessageDecoder;
import io.netty.handler.codec.LineBasedFrameDecoder;
import io.netty.handler.codec.ProtocolDetectionResult;
import io.netty.util.CharsetUtil;
import java.util.List;
/**
* Decodes an HAProxy proxy protocol header
*
* @see <a href="http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt">Proxy Protocol Specification</a>
*/
public class HAProxyMessageDecoder extends ByteToMessageDecoder {
/**
* Maximum possible length of a v1 proxy protocol header per spec
*/
private static final int V1_MAX_LENGTH = 108;
/**
* Maximum possible length of a v2 proxy protocol header (fixed 16 bytes + max unsigned short)
*/
private static final int V2_MAX_LENGTH = 16 + 65535;
/**
* Minimum possible length of a fully functioning v2 proxy protocol header (fixed 16 bytes + v2 address info space)
*/
private static final int V2_MIN_LENGTH = 16 + 216;
/**
* Maximum possible length for v2 additional TLV data (max unsigned short - max v2 address info space)
*/
private static final int V2_MAX_TLV = 65535 - 216;
/**
* Version 1 header delimiter is always '\r\n' per spec
*/
private static final int DELIMITER_LENGTH = 2;
/**
* Binary header prefix
*/
private static final byte[] BINARY_PREFIX = {
(byte) 0x0D,
(byte) 0x0A,
(byte) 0x0D,
(byte) 0x0A,
(byte) 0x00,
(byte) 0x0D,
(byte) 0x0A,
(byte) 0x51,
(byte) 0x55,
(byte) 0x49,
(byte) 0x54,
(byte) 0x0A
};
private static final byte[] TEXT_PREFIX = {
(byte) 'P',
(byte) 'R',
(byte) 'O',
(byte) 'X',
(byte) 'Y',
};
/**
* Binary header prefix length
*/
private static final int BINARY_PREFIX_LENGTH = BINARY_PREFIX.length;
/**
* {@link ProtocolDetectionResult} for {@link HAProxyProtocolVersion#V1}.
*/
private static final ProtocolDetectionResult<HAProxyProtocolVersion> DETECTION_RESULT_V1 =
ProtocolDetectionResult.detected(HAProxyProtocolVersion.V1);
/**
* {@link ProtocolDetectionResult} for {@link HAProxyProtocolVersion#V2}.
*/
private static final ProtocolDetectionResult<HAProxyProtocolVersion> DETECTION_RESULT_V2 =
ProtocolDetectionResult.detected(HAProxyProtocolVersion.V2);
/**
* {@code true} if we're discarding input because we're already over maxLength
*/
private boolean discarding;
/**
* Number of discarded bytes
*/
private int discardedBytes;
/**
* {@code true} if we're finished decoding the proxy protocol header
*/
private boolean finished;
/**
* Protocol specification version
*/
private int version = -1;
/**
* The latest v2 spec (2014/05/18) allows for additional data to be sent in the proxy protocol header beyond the
* address information block so now we need a configurable max header size
*/
private final int v2MaxHeaderSize;
/**
* Creates a new decoder with no additional data (TLV) restrictions
*/
public HAProxyMessageDecoder() {
v2MaxHeaderSize = V2_MAX_LENGTH;
}
/**
* Creates a new decoder with restricted additional data (TLV) size
* <p>
* <b>Note:</b> limiting TLV size only affects processing of v2, binary headers. Also, as allowed by the 1.5 spec
* TLV data is currently ignored. For maximum performance it would be best to configure your upstream proxy host to
* <b>NOT</b> send TLV data and instantiate with a max TLV size of {@code 0}.
* </p>
*
* @param maxTlvSize maximum number of bytes allowed for additional data (Type-Length-Value vectors) in a v2 header
*/
public HAProxyMessageDecoder(int maxTlvSize) {
if (maxTlvSize < 1) {
v2MaxHeaderSize = V2_MIN_LENGTH;
} else if (maxTlvSize > V2_MAX_TLV) {
v2MaxHeaderSize = V2_MAX_LENGTH;
} else {
int calcMax = maxTlvSize + V2_MIN_LENGTH;
if (calcMax > V2_MAX_LENGTH) {
v2MaxHeaderSize = V2_MAX_LENGTH;
} else {
v2MaxHeaderSize = calcMax;
}
}
}
/**
* Returns the proxy protocol specification version in the buffer if the version is found.
* Returns -1 if no version was found in the buffer.
*/
private static int findVersion(final ByteBuf buffer) {
final int n = buffer.readableBytes();
// per spec, the version number is found in the 13th byte
if (n < 13) {
return -1;
}
int idx = buffer.readerIndex();
return match(BINARY_PREFIX, buffer, idx) ? buffer.getByte(idx + BINARY_PREFIX_LENGTH) : 1;
}
/**
* Returns the index in the buffer of the end of header if found.
* Returns -1 if no end of header was found in the buffer.
*/
private static int findEndOfHeader(final ByteBuf buffer) {
final int n = buffer.readableBytes();
// per spec, the 15th and 16th bytes contain the address length in bytes
if (n < 16) {
return -1;
}
int offset = buffer.readerIndex() + 14;
// the total header length will be a fixed 16 byte sequence + the dynamic address information block
int totalHeaderBytes = 16 + buffer.getUnsignedShort(offset);
// ensure we actually have the full header available
if (n >= totalHeaderBytes) {
return totalHeaderBytes;
} else {
return -1;
}
}
/**
* Returns the index in the buffer of the end of line found.
* Returns -1 if no end of line was found in the buffer.
*/
private static int findEndOfLine(final ByteBuf buffer) {
final int n = buffer.writerIndex();
for (int i = buffer.readerIndex(); i < n; i++) {
final byte b = buffer.getByte(i);
if (b == '\r' && i < n - 1 && buffer.getByte(i + 1) == '\n') {
return i; // \r\n
}
}
return -1; // Not found.
}
@Override
public boolean isSingleDecode() {
// ByteToMessageDecoder uses this method to optionally break out of the decoding loop after each unit of work.
// Since we only ever want to decode a single header we always return true to save a bit of work here.
return true;
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
super.channelRead(ctx, msg);
if (finished) {
ctx.pipeline().remove(this);
}
}
@Override
protected final void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
// determine the specification version
if (version == -1) {
if ((version = findVersion(in)) == -1) {
return;
}
}
ByteBuf decoded;
if (version == 1) {
decoded = decodeLine(ctx, in);
} else {
decoded = decodeStruct(ctx, in);
}
if (decoded != null) {
finished = true;
try {
if (version == 1) {
out.add(HAProxyMessage.decodeHeader(decoded.toString(CharsetUtil.US_ASCII)));
} else {
out.add(HAProxyMessage.decodeHeader(decoded));
}
} catch (HAProxyProtocolException e) {
fail(ctx, null, e);
}
}
}
/**
* Create a frame out of the {@link ByteBuf} and return it.
* Based on code from {@link LineBasedFrameDecoder#decode(ChannelHandlerContext, ByteBuf)}.
*
* @param ctx the {@link ChannelHandlerContext} which this {@link HAProxyMessageDecoder} belongs to
* @param buffer the {@link ByteBuf} from which to read data
* @return frame the {@link ByteBuf} which represent the frame or {@code null} if no frame could
* be created
*/
private ByteBuf decodeStruct(ChannelHandlerContext ctx, ByteBuf buffer) throws Exception {
final int eoh = findEndOfHeader(buffer);
if (!discarding) {
if (eoh >= 0) {
final int length = eoh - buffer.readerIndex();
if (length > v2MaxHeaderSize) {
buffer.readerIndex(eoh);
failOverLimit(ctx, length);
return null;
}
return buffer.readSlice(length);
} else {
final int length = buffer.readableBytes();
if (length > v2MaxHeaderSize) {
discardedBytes = length;
buffer.skipBytes(length);
discarding = true;
failOverLimit(ctx, "over " + discardedBytes);
}
return null;
}
} else {
if (eoh >= 0) {
buffer.readerIndex(eoh);
discardedBytes = 0;
discarding = false;
} else {
discardedBytes = buffer.readableBytes();
buffer.skipBytes(discardedBytes);
}
return null;
}
}
/**
* Create a frame out of the {@link ByteBuf} and return it.
* Based on code from {@link LineBasedFrameDecoder#decode(ChannelHandlerContext, ByteBuf)}.
*
* @param ctx the {@link ChannelHandlerContext} which this {@link HAProxyMessageDecoder} belongs to
* @param buffer the {@link ByteBuf} from which to read data
* @return frame the {@link ByteBuf} which represent the frame or {@code null} if no frame could
* be created
*/
private ByteBuf decodeLine(ChannelHandlerContext ctx, ByteBuf buffer) throws Exception {
final int eol = findEndOfLine(buffer);
if (!discarding) {
if (eol >= 0) {
final int length = eol - buffer.readerIndex();
if (length > V1_MAX_LENGTH) {
buffer.readerIndex(eol + DELIMITER_LENGTH);
failOverLimit(ctx, length);
return null;
}
ByteBuf frame = buffer.readSlice(length);
buffer.skipBytes(DELIMITER_LENGTH);
return frame;
} else {
final int length = buffer.readableBytes();
if (length > V1_MAX_LENGTH) {
discardedBytes = length;
buffer.skipBytes(length);
discarding = true;
failOverLimit(ctx, "over " + discardedBytes);
}
return null;
}
} else {
if (eol >= 0) {
final int delimLength = buffer.getByte(eol) == '\r' ? 2 : 1;
buffer.readerIndex(eol + delimLength);
discardedBytes = 0;
discarding = false;
} else {
discardedBytes = buffer.readableBytes();
buffer.skipBytes(discardedBytes);
}
return null;
}
}
private void failOverLimit(final ChannelHandlerContext ctx, int length) {
failOverLimit(ctx, String.valueOf(length));
}
private void failOverLimit(final ChannelHandlerContext ctx, String length) {
int maxLength = version == 1 ? V1_MAX_LENGTH : v2MaxHeaderSize;
fail(ctx, "header length (" + length + ") exceeds the allowed maximum (" + maxLength + ')', null);
}
private void fail(final ChannelHandlerContext ctx, String errMsg, Throwable t) {
finished = true;
ctx.close(); // drop connection immediately per spec
HAProxyProtocolException ppex;
if (errMsg != null && t != null) {
ppex = new HAProxyProtocolException(errMsg, t);
} else if (errMsg != null) {
ppex = new HAProxyProtocolException(errMsg);
} else if (t != null) {
ppex = new HAProxyProtocolException(t);
} else {
ppex = new HAProxyProtocolException();
}
throw ppex;
}
/**
* Returns the {@link ProtocolDetectionResult} for the given {@link ByteBuf}.
*/
public static ProtocolDetectionResult<HAProxyProtocolVersion> detectProtocol(ByteBuf buffer) {
if (buffer.readableBytes() < 12) {
return ProtocolDetectionResult.needsMoreData();
}
int idx = buffer.readerIndex();
if (match(BINARY_PREFIX, buffer, idx)) {
return DETECTION_RESULT_V2;
}
if (match(TEXT_PREFIX, buffer, idx)) {
return DETECTION_RESULT_V1;
}
return ProtocolDetectionResult.invalid();
}
private static boolean match(byte[] prefix, ByteBuf buffer, int idx) {
for (int i = 0; i < prefix.length; i++) {
final byte b = buffer.getByte(idx + i);
if (b != prefix[i]) {
return false;
}
}
return true;
}
}