0433c61674
Motivation: Sometimes it is useful to detect if a ByteBuf contains a HAProxy header, for example if you want to write something like the PortUnification example. Modifications: - Add ProtocolDetectionResult which can be used as a return type for detecting different protocol. - Add new method which allows to detect HA Proxy messages. Result: Easier to detect protocol.
403 lines
14 KiB
Java
403 lines
14 KiB
Java
/*
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* Copyright 2014 The Netty Project
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*
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* The Netty Project licenses this file to you under the Apache License,
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* version 2.0 (the "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at:
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
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* WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
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* License for the specific language governing permissions and limitations
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* under the License.
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*/
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package io.netty.handler.codec.haproxy;
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import io.netty.buffer.ByteBuf;
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import io.netty.channel.ChannelHandlerContext;
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import io.netty.handler.codec.ByteToMessageDecoder;
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import io.netty.handler.codec.LineBasedFrameDecoder;
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import io.netty.handler.codec.ProtocolDetectionResult;
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import io.netty.util.CharsetUtil;
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import java.util.List;
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/**
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* Decodes an HAProxy proxy protocol header
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*
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* @see <a href="http://haproxy.1wt.eu/download/1.5/doc/proxy-protocol.txt">Proxy Protocol Specification</a>
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*/
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public class HAProxyMessageDecoder extends ByteToMessageDecoder {
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/**
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* Maximum possible length of a v1 proxy protocol header per spec
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*/
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private static final int V1_MAX_LENGTH = 108;
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/**
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* Maximum possible length of a v2 proxy protocol header (fixed 16 bytes + max unsigned short)
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*/
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private static final int V2_MAX_LENGTH = 16 + 65535;
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/**
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* Minimum possible length of a fully functioning v2 proxy protocol header (fixed 16 bytes + v2 address info space)
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*/
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private static final int V2_MIN_LENGTH = 16 + 216;
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/**
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* Maximum possible length for v2 additional TLV data (max unsigned short - max v2 address info space)
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*/
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private static final int V2_MAX_TLV = 65535 - 216;
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/**
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* Version 1 header delimiter is always '\r\n' per spec
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*/
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private static final int DELIMITER_LENGTH = 2;
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/**
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* Binary header prefix
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*/
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private static final byte[] BINARY_PREFIX = {
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(byte) 0x0D,
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(byte) 0x0A,
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(byte) 0x0D,
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(byte) 0x0A,
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(byte) 0x00,
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(byte) 0x0D,
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(byte) 0x0A,
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(byte) 0x51,
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(byte) 0x55,
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(byte) 0x49,
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(byte) 0x54,
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(byte) 0x0A
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};
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private static final byte[] TEXT_PREFIX = {
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(byte) 'P',
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(byte) 'R',
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(byte) 'O',
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(byte) 'X',
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(byte) 'Y',
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};
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/**
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* Binary header prefix length
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*/
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private static final int BINARY_PREFIX_LENGTH = BINARY_PREFIX.length;
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/**
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* {@link ProtocolDetectionResult} for {@link HAProxyProtocolVersion#V1}.
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*/
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private static final ProtocolDetectionResult<HAProxyProtocolVersion> DETECTION_RESULT_V1 =
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ProtocolDetectionResult.detected(HAProxyProtocolVersion.V1);
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/**
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* {@link ProtocolDetectionResult} for {@link HAProxyProtocolVersion#V2}.
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*/
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private static final ProtocolDetectionResult<HAProxyProtocolVersion> DETECTION_RESULT_V2 =
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ProtocolDetectionResult.detected(HAProxyProtocolVersion.V2);
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/**
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* {@code true} if we're discarding input because we're already over maxLength
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*/
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private boolean discarding;
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/**
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* Number of discarded bytes
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*/
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private int discardedBytes;
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/**
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* {@code true} if we're finished decoding the proxy protocol header
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*/
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private boolean finished;
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/**
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* Protocol specification version
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*/
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private int version = -1;
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/**
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* The latest v2 spec (2014/05/18) allows for additional data to be sent in the proxy protocol header beyond the
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* address information block so now we need a configurable max header size
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*/
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private final int v2MaxHeaderSize;
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/**
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* Creates a new decoder with no additional data (TLV) restrictions
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*/
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public HAProxyMessageDecoder() {
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v2MaxHeaderSize = V2_MAX_LENGTH;
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}
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/**
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* Creates a new decoder with restricted additional data (TLV) size
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* <p>
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* <b>Note:</b> limiting TLV size only affects processing of v2, binary headers. Also, as allowed by the 1.5 spec
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* TLV data is currently ignored. For maximum performance it would be best to configure your upstream proxy host to
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* <b>NOT</b> send TLV data and instantiate with a max TLV size of {@code 0}.
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* </p>
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*
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* @param maxTlvSize maximum number of bytes allowed for additional data (Type-Length-Value vectors) in a v2 header
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*/
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public HAProxyMessageDecoder(int maxTlvSize) {
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if (maxTlvSize < 1) {
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v2MaxHeaderSize = V2_MIN_LENGTH;
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} else if (maxTlvSize > V2_MAX_TLV) {
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v2MaxHeaderSize = V2_MAX_LENGTH;
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} else {
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int calcMax = maxTlvSize + V2_MIN_LENGTH;
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if (calcMax > V2_MAX_LENGTH) {
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v2MaxHeaderSize = V2_MAX_LENGTH;
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} else {
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v2MaxHeaderSize = calcMax;
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}
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}
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}
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/**
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* Returns the proxy protocol specification version in the buffer if the version is found.
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* Returns -1 if no version was found in the buffer.
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*/
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private static int findVersion(final ByteBuf buffer) {
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final int n = buffer.readableBytes();
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// per spec, the version number is found in the 13th byte
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if (n < 13) {
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return -1;
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}
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int idx = buffer.readerIndex();
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return match(BINARY_PREFIX, buffer, idx) ? buffer.getByte(idx + BINARY_PREFIX_LENGTH) : 1;
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}
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/**
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* Returns the index in the buffer of the end of header if found.
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* Returns -1 if no end of header was found in the buffer.
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*/
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private static int findEndOfHeader(final ByteBuf buffer) {
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final int n = buffer.readableBytes();
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// per spec, the 15th and 16th bytes contain the address length in bytes
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if (n < 16) {
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return -1;
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}
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int offset = buffer.readerIndex() + 14;
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// the total header length will be a fixed 16 byte sequence + the dynamic address information block
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int totalHeaderBytes = 16 + buffer.getUnsignedShort(offset);
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// ensure we actually have the full header available
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if (n >= totalHeaderBytes) {
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return totalHeaderBytes;
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} else {
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return -1;
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}
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}
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/**
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* Returns the index in the buffer of the end of line found.
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* Returns -1 if no end of line was found in the buffer.
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*/
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private static int findEndOfLine(final ByteBuf buffer) {
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final int n = buffer.writerIndex();
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for (int i = buffer.readerIndex(); i < n; i++) {
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final byte b = buffer.getByte(i);
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if (b == '\r' && i < n - 1 && buffer.getByte(i + 1) == '\n') {
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return i; // \r\n
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}
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}
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return -1; // Not found.
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}
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@Override
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public boolean isSingleDecode() {
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// ByteToMessageDecoder uses this method to optionally break out of the decoding loop after each unit of work.
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// Since we only ever want to decode a single header we always return true to save a bit of work here.
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return true;
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}
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@Override
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public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
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super.channelRead(ctx, msg);
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if (finished) {
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ctx.pipeline().remove(this);
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}
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}
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@Override
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protected final void decode(ChannelHandlerContext ctx, ByteBuf in, List<Object> out) throws Exception {
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// determine the specification version
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if (version == -1) {
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if ((version = findVersion(in)) == -1) {
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return;
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}
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}
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ByteBuf decoded;
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if (version == 1) {
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decoded = decodeLine(ctx, in);
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} else {
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decoded = decodeStruct(ctx, in);
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}
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if (decoded != null) {
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finished = true;
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try {
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if (version == 1) {
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out.add(HAProxyMessage.decodeHeader(decoded.toString(CharsetUtil.US_ASCII)));
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} else {
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out.add(HAProxyMessage.decodeHeader(decoded));
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}
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} catch (HAProxyProtocolException e) {
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fail(ctx, null, e);
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}
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}
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}
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/**
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* Create a frame out of the {@link ByteBuf} and return it.
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* Based on code from {@link LineBasedFrameDecoder#decode(ChannelHandlerContext, ByteBuf)}.
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*
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* @param ctx the {@link ChannelHandlerContext} which this {@link HAProxyMessageDecoder} belongs to
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* @param buffer the {@link ByteBuf} from which to read data
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* @return frame the {@link ByteBuf} which represent the frame or {@code null} if no frame could
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* be created
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*/
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private ByteBuf decodeStruct(ChannelHandlerContext ctx, ByteBuf buffer) throws Exception {
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final int eoh = findEndOfHeader(buffer);
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if (!discarding) {
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if (eoh >= 0) {
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final int length = eoh - buffer.readerIndex();
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if (length > v2MaxHeaderSize) {
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buffer.readerIndex(eoh);
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failOverLimit(ctx, length);
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return null;
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}
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return buffer.readSlice(length);
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} else {
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final int length = buffer.readableBytes();
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if (length > v2MaxHeaderSize) {
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discardedBytes = length;
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buffer.skipBytes(length);
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discarding = true;
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failOverLimit(ctx, "over " + discardedBytes);
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}
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return null;
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}
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} else {
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if (eoh >= 0) {
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buffer.readerIndex(eoh);
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discardedBytes = 0;
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discarding = false;
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} else {
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discardedBytes = buffer.readableBytes();
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buffer.skipBytes(discardedBytes);
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}
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return null;
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}
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}
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/**
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* Create a frame out of the {@link ByteBuf} and return it.
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* Based on code from {@link LineBasedFrameDecoder#decode(ChannelHandlerContext, ByteBuf)}.
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*
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* @param ctx the {@link ChannelHandlerContext} which this {@link HAProxyMessageDecoder} belongs to
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* @param buffer the {@link ByteBuf} from which to read data
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* @return frame the {@link ByteBuf} which represent the frame or {@code null} if no frame could
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* be created
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*/
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private ByteBuf decodeLine(ChannelHandlerContext ctx, ByteBuf buffer) throws Exception {
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final int eol = findEndOfLine(buffer);
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if (!discarding) {
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if (eol >= 0) {
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final int length = eol - buffer.readerIndex();
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if (length > V1_MAX_LENGTH) {
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buffer.readerIndex(eol + DELIMITER_LENGTH);
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failOverLimit(ctx, length);
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return null;
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}
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ByteBuf frame = buffer.readSlice(length);
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buffer.skipBytes(DELIMITER_LENGTH);
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return frame;
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} else {
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final int length = buffer.readableBytes();
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if (length > V1_MAX_LENGTH) {
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discardedBytes = length;
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buffer.skipBytes(length);
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discarding = true;
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failOverLimit(ctx, "over " + discardedBytes);
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}
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return null;
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}
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} else {
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if (eol >= 0) {
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final int delimLength = buffer.getByte(eol) == '\r' ? 2 : 1;
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buffer.readerIndex(eol + delimLength);
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discardedBytes = 0;
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discarding = false;
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} else {
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discardedBytes = buffer.readableBytes();
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buffer.skipBytes(discardedBytes);
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}
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return null;
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}
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}
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private void failOverLimit(final ChannelHandlerContext ctx, int length) {
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failOverLimit(ctx, String.valueOf(length));
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}
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private void failOverLimit(final ChannelHandlerContext ctx, String length) {
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int maxLength = version == 1 ? V1_MAX_LENGTH : v2MaxHeaderSize;
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fail(ctx, "header length (" + length + ") exceeds the allowed maximum (" + maxLength + ')', null);
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}
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private void fail(final ChannelHandlerContext ctx, String errMsg, Throwable t) {
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finished = true;
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ctx.close(); // drop connection immediately per spec
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HAProxyProtocolException ppex;
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if (errMsg != null && t != null) {
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ppex = new HAProxyProtocolException(errMsg, t);
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} else if (errMsg != null) {
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ppex = new HAProxyProtocolException(errMsg);
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} else if (t != null) {
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ppex = new HAProxyProtocolException(t);
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} else {
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ppex = new HAProxyProtocolException();
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}
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throw ppex;
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}
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/**
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* Returns the {@link ProtocolDetectionResult} for the given {@link ByteBuf}.
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*/
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public static ProtocolDetectionResult<HAProxyProtocolVersion> detectProtocol(ByteBuf buffer) {
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if (buffer.readableBytes() < 12) {
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return ProtocolDetectionResult.needsMoreData();
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}
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int idx = buffer.readerIndex();
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if (match(BINARY_PREFIX, buffer, idx)) {
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return DETECTION_RESULT_V2;
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}
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if (match(TEXT_PREFIX, buffer, idx)) {
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return DETECTION_RESULT_V1;
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}
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return ProtocolDetectionResult.invalid();
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}
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private static boolean match(byte[] prefix, ByteBuf buffer, int idx) {
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for (int i = 0; i < prefix.length; i++) {
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final byte b = buffer.getByte(idx + i);
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if (b != prefix[i]) {
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return false;
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}
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}
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return true;
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}
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}
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