com.undefinedlabs.scope.deps.okhttp3.internal.ws.WebSocketWriter Maven / Gradle / Ivy

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Scope is a APM for tests to give engineering teams unprecedented visibility into their CI process to quickly identify, troubleshoot and fix failed builds. This artifact contains dependencies for Scope.
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package com.undefinedlabs.scope.deps.okhttp3.internal.ws;

import com.undefinedlabs.scope.deps.okio.*;

import java.io.IOException;
import java.util.Random;

import static com.undefinedlabs.scope.deps.okhttp3.internal.ws.WebSocketProtocol.*;

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 Section 7.4 of RFC 6455 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;
        }
    }
}