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/*
* 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 org.jboss.netty.handler.codec.spdy;
import static org.jboss.netty.handler.codec.spdy.SpdyCodecUtil.*;
import org.jboss.netty.buffer.ChannelBuffer;
import org.jboss.netty.buffer.ChannelBuffers;
/**
* Decodes {@link ChannelBuffer}s into SPDY Frames.
*/
public class SpdyFrameDecoder {
private final int spdyVersion;
private final int maxChunkSize;
private final SpdyFrameDecoderDelegate delegate;
private State state;
// SPDY common header fields
private byte flags;
private int length;
private int streamId;
private int numSettings;
private enum State {
READ_COMMON_HEADER,
READ_DATA_FRAME,
READ_SYN_STREAM_FRAME,
READ_SYN_REPLY_FRAME,
READ_RST_STREAM_FRAME,
READ_SETTINGS_FRAME,
READ_SETTING,
READ_PING_FRAME,
READ_GOAWAY_FRAME,
READ_HEADERS_FRAME,
READ_WINDOW_UPDATE_FRAME,
READ_HEADER_BLOCK,
DISCARD_FRAME,
FRAME_ERROR
}
/**
* Creates a new instance with the specified {@code version}
* and the default {@code maxChunkSize (8192)}.
*/
public SpdyFrameDecoder(SpdyVersion spdyVersion, SpdyFrameDecoderDelegate delegate) {
this(spdyVersion, delegate, 8192);
}
/**
* Creates a new instance with the specified parameters.
*/
public SpdyFrameDecoder(SpdyVersion spdyVersion, SpdyFrameDecoderDelegate delegate, int maxChunkSize) {
if (spdyVersion == null) {
throw new NullPointerException("spdyVersion");
}
if (delegate == null) {
throw new NullPointerException("delegate");
}
if (maxChunkSize <= 0) {
throw new IllegalArgumentException(
"maxChunkSize must be a positive integer: " + maxChunkSize);
}
this.spdyVersion = spdyVersion.getVersion();
this.delegate = delegate;
this.maxChunkSize = maxChunkSize;
state = State.READ_COMMON_HEADER;
}
public void decode(ChannelBuffer buffer) {
boolean last;
int statusCode;
while (true) {
switch(state) {
case READ_COMMON_HEADER:
if (buffer.readableBytes() < SPDY_HEADER_SIZE) {
return;
}
int frameOffset = buffer.readerIndex();
int flagsOffset = frameOffset + SPDY_HEADER_FLAGS_OFFSET;
int lengthOffset = frameOffset + SPDY_HEADER_LENGTH_OFFSET;
buffer.skipBytes(SPDY_HEADER_SIZE);
boolean control = (buffer.getByte(frameOffset) & 0x80) != 0;
int version;
int type;
if (control) {
// Decode control frame common header
version = getUnsignedShort(buffer, frameOffset) & 0x7FFF;
type = getUnsignedShort(buffer, frameOffset + SPDY_HEADER_TYPE_OFFSET);
streamId = 0; // Default to session Stream-ID
} else {
// Decode data frame common header
version = spdyVersion; // Default to expected version
type = SPDY_DATA_FRAME;
streamId = getUnsignedInt(buffer, frameOffset);
}
flags = buffer.getByte(flagsOffset);
length = getUnsignedMedium(buffer, lengthOffset);
// Check version first then validity
if (version != spdyVersion) {
state = State.FRAME_ERROR;
delegate.readFrameError("Invalid SPDY Version");
} else if (!isValidFrameHeader(streamId, type, flags, length)) {
state = State.FRAME_ERROR;
delegate.readFrameError("Invalid Frame Error");
} else {
state = getNextState(type, length);
}
break;
case READ_DATA_FRAME:
if (length == 0) {
state = State.READ_COMMON_HEADER;
delegate.readDataFrame(streamId, hasFlag(flags, SPDY_DATA_FLAG_FIN), ChannelBuffers.EMPTY_BUFFER);
break;
}
// Generate data frames that do not exceed maxChunkSize
int dataLength = Math.min(maxChunkSize, length);
// Wait until entire frame is readable
if (buffer.readableBytes() < dataLength) {
return;
}
ChannelBuffer data = buffer.readBytes(dataLength);
length -= dataLength;
if (length == 0) {
state = State.READ_COMMON_HEADER;
}
last = length == 0 && hasFlag(flags, SPDY_DATA_FLAG_FIN);
delegate.readDataFrame(streamId, last, data);
break;
case READ_SYN_STREAM_FRAME:
if (buffer.readableBytes() < 10) {
return;
}
int offset = buffer.readerIndex();
streamId = getUnsignedInt(buffer, offset);
int associatedToStreamId = getUnsignedInt(buffer, offset + 4);
byte priority = (byte) (buffer.getByte(offset + 8) >> 5 & 0x07);
last = hasFlag(flags, SPDY_FLAG_FIN);
boolean unidirectional = hasFlag(flags, SPDY_FLAG_UNIDIRECTIONAL);
buffer.skipBytes(10);
length -= 10;
if (streamId == 0) {
state = State.FRAME_ERROR;
delegate.readFrameError("Invalid SYN_STREAM Frame");
} else {
state = State.READ_HEADER_BLOCK;
delegate.readSynStreamFrame(streamId, associatedToStreamId, priority, last, unidirectional);
}
break;
case READ_SYN_REPLY_FRAME:
if (buffer.readableBytes() < 4) {
return;
}
streamId = getUnsignedInt(buffer, buffer.readerIndex());
last = hasFlag(flags, SPDY_FLAG_FIN);
buffer.skipBytes(4);
length -= 4;
if (streamId == 0) {
state = State.FRAME_ERROR;
delegate.readFrameError("Invalid SYN_REPLY Frame");
} else {
state = State.READ_HEADER_BLOCK;
delegate.readSynReplyFrame(streamId, last);
}
break;
case READ_RST_STREAM_FRAME:
if (buffer.readableBytes() < 8) {
return;
}
streamId = getUnsignedInt(buffer, buffer.readerIndex());
statusCode = getSignedInt(buffer, buffer.readerIndex() + 4);
buffer.skipBytes(8);
if (streamId == 0 || statusCode == 0) {
state = State.FRAME_ERROR;
delegate.readFrameError("Invalid RST_STREAM Frame");
} else {
state = State.READ_COMMON_HEADER;
delegate.readRstStreamFrame(streamId, statusCode);
}
break;
case READ_SETTINGS_FRAME:
if (buffer.readableBytes() < 4) {
return;
}
boolean clear = hasFlag(flags, SPDY_SETTINGS_CLEAR);
numSettings = getUnsignedInt(buffer, buffer.readerIndex());
buffer.skipBytes(4);
length -= 4;
// Validate frame length against number of entries. Each ID/Value entry is 8 bytes.
if ((length & 0x07) != 0 || length >> 3 != numSettings) {
state = State.FRAME_ERROR;
delegate.readFrameError("Invalid SETTINGS Frame");
} else {
state = State.READ_SETTING;
delegate.readSettingsFrame(clear);
}
break;
case READ_SETTING:
if (numSettings == 0) {
state = State.READ_COMMON_HEADER;
delegate.readSettingsEnd();
break;
}
if (buffer.readableBytes() < 8) {
return;
}
byte settingsFlags = buffer.getByte(buffer.readerIndex());
int id = getUnsignedMedium(buffer, buffer.readerIndex() + 1);
int value = getSignedInt(buffer, buffer.readerIndex() + 4);
boolean persistValue = hasFlag(settingsFlags, SPDY_SETTINGS_PERSIST_VALUE);
boolean persisted = hasFlag(settingsFlags, SPDY_SETTINGS_PERSISTED);
buffer.skipBytes(8);
--numSettings;
delegate.readSetting(id, value, persistValue, persisted);
break;
case READ_PING_FRAME:
if (buffer.readableBytes() < 4) {
return;
}
int pingId = getSignedInt(buffer, buffer.readerIndex());
buffer.skipBytes(4);
state = State.READ_COMMON_HEADER;
delegate.readPingFrame(pingId);
break;
case READ_GOAWAY_FRAME:
if (buffer.readableBytes() < 8) {
return;
}
int lastGoodStreamId = getUnsignedInt(buffer, buffer.readerIndex());
statusCode = getSignedInt(buffer, buffer.readerIndex() + 4);
buffer.skipBytes(8);
state = State.READ_COMMON_HEADER;
delegate.readGoAwayFrame(lastGoodStreamId, statusCode);
break;
case READ_HEADERS_FRAME:
if (buffer.readableBytes() < 4) {
return;
}
streamId = getUnsignedInt(buffer, buffer.readerIndex());
last = hasFlag(flags, SPDY_FLAG_FIN);
buffer.skipBytes(4);
length -= 4;
if (streamId == 0) {
state = State.FRAME_ERROR;
delegate.readFrameError("Invalid HEADERS Frame");
} else {
state = State.READ_HEADER_BLOCK;
delegate.readHeadersFrame(streamId, last);
}
break;
case READ_WINDOW_UPDATE_FRAME:
if (buffer.readableBytes() < 8) {
return;
}
streamId = getUnsignedInt(buffer, buffer.readerIndex());
int deltaWindowSize = getUnsignedInt(buffer, buffer.readerIndex() + 4);
buffer.skipBytes(8);
if (deltaWindowSize == 0) {
state = State.FRAME_ERROR;
delegate.readFrameError("Invalid WINDOW_UPDATE Frame");
} else {
state = State.READ_COMMON_HEADER;
delegate.readWindowUpdateFrame(streamId, deltaWindowSize);
}
break;
case READ_HEADER_BLOCK:
if (length == 0) {
state = State.READ_COMMON_HEADER;
delegate.readHeaderBlockEnd();
break;
}
if (!buffer.readable()) {
return;
}
int compressedBytes = Math.min(buffer.readableBytes(), length);
ChannelBuffer headerBlock = buffer.readBytes(compressedBytes);
length -= compressedBytes;
delegate.readHeaderBlock(headerBlock);
break;
case DISCARD_FRAME:
int numBytes = Math.min(buffer.readableBytes(), length);
buffer.skipBytes(numBytes);
length -= numBytes;
if (length == 0) {
state = State.READ_COMMON_HEADER;
break;
}
return;
case FRAME_ERROR:
buffer.skipBytes(buffer.readableBytes());
return;
default:
throw new Error("Shouldn't reach here.");
}
}
}
private static boolean hasFlag(byte flags, byte flag) {
return (flags & flag) != 0;
}
private static State getNextState(int type, int length) {
switch (type) {
case SPDY_DATA_FRAME:
return State.READ_DATA_FRAME;
case SPDY_SYN_STREAM_FRAME:
return State.READ_SYN_STREAM_FRAME;
case SPDY_SYN_REPLY_FRAME:
return State.READ_SYN_REPLY_FRAME;
case SPDY_RST_STREAM_FRAME:
return State.READ_RST_STREAM_FRAME;
case SPDY_SETTINGS_FRAME:
return State.READ_SETTINGS_FRAME;
case SPDY_PING_FRAME:
return State.READ_PING_FRAME;
case SPDY_GOAWAY_FRAME:
return State.READ_GOAWAY_FRAME;
case SPDY_HEADERS_FRAME:
return State.READ_HEADERS_FRAME;
case SPDY_WINDOW_UPDATE_FRAME:
return State.READ_WINDOW_UPDATE_FRAME;
default:
if (length != 0) {
return State.DISCARD_FRAME;
} else {
return State.READ_COMMON_HEADER;
}
}
}
private static boolean isValidFrameHeader(int streamId, int type, byte flags, int length) {
switch (type) {
case SPDY_DATA_FRAME:
return streamId != 0;
case SPDY_SYN_STREAM_FRAME:
return length >= 10;
case SPDY_SYN_REPLY_FRAME:
return length >= 4;
case SPDY_RST_STREAM_FRAME:
return flags == 0 && length == 8;
case SPDY_SETTINGS_FRAME:
return length >= 4;
case SPDY_PING_FRAME:
return length == 4;
case SPDY_GOAWAY_FRAME:
return length == 8;
case SPDY_HEADERS_FRAME:
return length >= 4;
case SPDY_WINDOW_UPDATE_FRAME:
return length == 8;
default:
return true;
}
}
}