/*
* Copyright (C) 2014 Square, Inc.
*
* Licensed 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 okhttp3.internal.ws;
import java.io.IOException;
import java.util.Random;
import okio.Buffer;
import okio.BufferedSink;
import okio.ByteString;
import okio.Sink;
import okio.Timeout;
import static okhttp3.internal.ws.WebSocketProtocol.B0_FLAG_FIN;
import static okhttp3.internal.ws.WebSocketProtocol.B1_FLAG_MASK;
import static okhttp3.internal.ws.WebSocketProtocol.OPCODE_CONTINUATION;
import static okhttp3.internal.ws.WebSocketProtocol.OPCODE_CONTROL_CLOSE;
import static okhttp3.internal.ws.WebSocketProtocol.OPCODE_CONTROL_PING;
import static okhttp3.internal.ws.WebSocketProtocol.OPCODE_CONTROL_PONG;
import static okhttp3.internal.ws.WebSocketProtocol.PAYLOAD_BYTE_MAX;
import static okhttp3.internal.ws.WebSocketProtocol.PAYLOAD_LONG;
import static okhttp3.internal.ws.WebSocketProtocol.PAYLOAD_SHORT;
import static okhttp3.internal.ws.WebSocketProtocol.PAYLOAD_SHORT_MAX;
import static okhttp3.internal.ws.WebSocketProtocol.toggleMask;
import static okhttp3.internal.ws.WebSocketProtocol.validateCloseCode;
/**
* An <a href="http://tools.ietf.org/html/rfc6455">RFC 6455</a>-compatible WebSocket frame writer.
*
* <p>This class is partially thread safe. Only a single "main" thread should be sending messages
* via calls to {@link #newMessageSink}, {@link #writePing}, or {@link #writeClose}. Other threads
* may call {@link #writePing}, {@link #writePong}, or {@link #writeClose} which will interleave on
* the wire with frames from the "main" sending thread.
*/
final class WebSocketWriter {
final boolean isClient;
final Random random;
/** Writes must be guarded by synchronizing on 'this'. */
final BufferedSink sink;
/** Access must be guarded by synchronizing on 'this'. */
boolean writerClosed;
final Buffer buffer = new Buffer();
final FrameSink frameSink = new FrameSink();
boolean activeWriter;
final byte[] maskKey;
final byte[] maskBuffer;
WebSocketWriter(boolean isClient, BufferedSink sink, Random random) {
if (sink == null) throw new NullPointerException("sink == null");
if (random == null) throw new NullPointerException("random == null");
this.isClient = isClient;
this.sink = sink;
this.random = random;
// Masks are only a concern for client writers.
maskKey = isClient ? new byte[4] : null;
maskBuffer = isClient ? new byte[8192] : null;
}
/** Send a ping with the supplied {@code payload}. */
void writePing(ByteString payload) throws IOException {
synchronized (this) {
writeControlFrameSynchronized(OPCODE_CONTROL_PING, payload);
}
}
/** Send a pong with the supplied {@code payload}. */
void writePong(ByteString payload) throws IOException {
synchronized (this) {
writeControlFrameSynchronized(OPCODE_CONTROL_PONG, payload);
}
}
/**
* Send a close frame with optional code and reason.
*
* @param code Status code as defined by <a
* href="http://tools.ietf.org/html/rfc6455#section-7.4">Section 7.4 of RFC 6455</a> or {@code 0}.
* @param reason Reason for shutting down or {@code null}.
*/
void writeClose(int code, ByteString reason) throws IOException {
ByteString payload = ByteString.EMPTY;
if (code != 0 || reason != null) {
if (code != 0) {
validateCloseCode(code);
}
Buffer buffer = new Buffer();
buffer.writeShort(code);
if (reason != null) {
buffer.write(reason);
}
payload = buffer.readByteString();
}
synchronized (this) {
try {
writeControlFrameSynchronized(OPCODE_CONTROL_CLOSE, payload);
} finally {
writerClosed = true;
}
}
}
private void writeControlFrameSynchronized(int opcode, ByteString payload) throws IOException {
assert Thread.holdsLock(this);
if (writerClosed) throw new IOException("closed");
int length = payload.size();
if (length > PAYLOAD_BYTE_MAX) {
throw new IllegalArgumentException(
"Payload size must be less than or equal to " + PAYLOAD_BYTE_MAX);
}
int b0 = B0_FLAG_FIN | opcode;
sink.writeByte(b0);
int b1 = length;
if (isClient) {
b1 |= B1_FLAG_MASK;
sink.writeByte(b1);
random.nextBytes(maskKey);
sink.write(maskKey);
byte[] bytes = payload.toByteArray();
toggleMask(bytes, bytes.length, maskKey, 0);
sink.write(bytes);
} else {
sink.writeByte(b1);
sink.write(payload);
}
sink.flush();
}
/**
* Stream a message payload as a series of frames. This allows control frames to be interleaved
* between parts of the message.
*/
Sink newMessageSink(int formatOpcode, long contentLength) {
if (activeWriter) {
throw new IllegalStateException("Another message writer is active. Did you call close()?");
}
activeWriter = true;
// Reset FrameSink state for a new writer.
frameSink.formatOpcode = formatOpcode;
frameSink.contentLength = contentLength;
frameSink.isFirstFrame = true;
frameSink.closed = false;
return frameSink;
}
void writeMessageFrameSynchronized(int formatOpcode, long byteCount, boolean isFirstFrame,
boolean isFinal) throws IOException {
assert Thread.holdsLock(this);
if (writerClosed) throw new IOException("closed");
int b0 = isFirstFrame ? formatOpcode : OPCODE_CONTINUATION;
if (isFinal) {
b0 |= B0_FLAG_FIN;
}
sink.writeByte(b0);
int b1 = 0;
if (isClient) {
b1 |= B1_FLAG_MASK;
}
if (byteCount <= PAYLOAD_BYTE_MAX) {
b1 |= (int) byteCount;
sink.writeByte(b1);
} else if (byteCount <= PAYLOAD_SHORT_MAX) {
b1 |= PAYLOAD_SHORT;
sink.writeByte(b1);
sink.writeShort((int) byteCount);
} else {
b1 |= PAYLOAD_LONG;
sink.writeByte(b1);
sink.writeLong(byteCount);
}
if (isClient) {
random.nextBytes(maskKey);
sink.write(maskKey);
for (long written = 0; written < byteCount; ) {
int toRead = (int) Math.min(byteCount, maskBuffer.length);
int read = buffer.read(maskBuffer, 0, toRead);
if (read == -1) throw new AssertionError();
toggleMask(maskBuffer, read, maskKey, written);
sink.write(maskBuffer, 0, read);
written += read;
}
} else {
sink.write(buffer, byteCount);
}
sink.emit();
}
final class FrameSink implements Sink {
int formatOpcode;
long contentLength;
boolean isFirstFrame;
boolean closed;
@Override public void write(Buffer source, long byteCount) throws IOException {
if (closed) throw new IOException("closed");
buffer.write(source, byteCount);
// Determine if this is a buffered write which we can defer until close() flushes.
boolean deferWrite = isFirstFrame
&& contentLength != -1
&& buffer.size() > contentLength - 8192 /* segment size */;
long emitCount = buffer.completeSegmentByteCount();
if (emitCount > 0 && !deferWrite) {
synchronized (WebSocketWriter.this) {
writeMessageFrameSynchronized(formatOpcode, emitCount, isFirstFrame, false /* final */);
}
isFirstFrame = false;
}
}
@Override public void flush() throws IOException {
if (closed) throw new IOException("closed");
synchronized (WebSocketWriter.this) {
writeMessageFrameSynchronized(formatOpcode, buffer.size(), isFirstFrame, false /* final */);
}
isFirstFrame = false;
}
@Override public Timeout timeout() {
return sink.timeout();
}
@SuppressWarnings("PointlessBitwiseExpression")
@Override public void close() throws IOException {
if (closed) throw new IOException("closed");
synchronized (WebSocketWriter.this) {
writeMessageFrameSynchronized(formatOpcode, buffer.size(), isFirstFrame, true /* final */);
}
closed = true;
activeWriter = false;
}
}
}