FrameReader.java

/*
 * Copyright (C) 2011 The Android Open Source Project
 *
 * 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.framed;

import java.io.Closeable;
import java.io.IOException;
import java.util.List;
import okio.BufferedSource;
import okio.ByteString;

/** Reads transport frames for SPDY/3 or HTTP/2. */
public interface FrameReader extends Closeable {
  void readConnectionPreface() throws IOException;

  boolean nextFrame(Handler handler) throws IOException;

  interface Handler {
    void data(boolean inFinished, int streamId, BufferedSource source, int length)
        throws IOException;

    /**
     * Create or update incoming headers, creating the corresponding streams if necessary. Frames
     * that trigger this are SPDY SYN_STREAM, HEADERS, and SYN_REPLY, and HTTP/2 HEADERS and
     * PUSH_PROMISE.
     *
     * @param outFinished true if the receiver should not send further frames.
     * @param inFinished true if the sender will not send further frames.
     * @param streamId the stream owning these headers.
     * @param associatedStreamId the stream that triggered the sender to create this stream.
     */
    void headers(boolean outFinished, boolean inFinished, int streamId, int associatedStreamId,
                 List<Header> headerBlock, HeadersMode headersMode);

    void rstStream(int streamId, ErrorCode errorCode);

    void settings(boolean clearPrevious, Settings settings);

    /** HTTP/2 only. */
    void ackSettings();

    /**
     * Read a connection-level ping from the peer.  {@code ack} indicates this is a reply.  Payload
     * parameters are different between SPDY/3 and HTTP/2.
     *
     * <p>In SPDY/3, only the first {@code payload1} parameter is set.  If the reader is a client,
     * it is an unsigned even number. Likewise, a server will receive an odd number.
     *
     * <p>In HTTP/2, both {@code payload1} and {@code payload2} parameters are set. The data is
     * opaque binary, and there are no rules on the content.
     */
    void ping(boolean ack, int payload1, int payload2);

    /**
     * The peer tells us to stop creating streams.  It is safe to replay streams with {@code ID >
     * lastGoodStreamId} on a new connection.  In- flight streams with {@code ID <=
     * lastGoodStreamId} can only be replayed on a new connection if they are idempotent.
     *
     * @param lastGoodStreamId the last stream ID the peer processed before sending this message. If
     * {@code lastGoodStreamId} is zero, the peer processed no frames.
     * @param errorCode reason for closing the connection.
     * @param debugData only valid for HTTP/2; opaque debug data to send.
     */
    void goAway(int lastGoodStreamId, ErrorCode errorCode, ByteString debugData);

    /**
     * Notifies that an additional {@code windowSizeIncrement} bytes can be sent on {@code
     * streamId}, or the connection if {@code streamId} is zero.
     */
    void windowUpdate(int streamId, long windowSizeIncrement);

    /**
     * Called when reading a headers or priority frame. This may be used to change the stream's
     * weight from the default (16) to a new value.
     *
     * @param streamId stream which has a priority change.
     * @param streamDependency the stream ID this stream is dependent on.
     * @param weight relative proportion of priority in [1..256].
     * @param exclusive inserts this stream ID as the sole child of {@code streamDependency}.
     */
    void priority(int streamId, int streamDependency, int weight, boolean exclusive);

    /**
     * HTTP/2 only. Receive a push promise header block. <p> A push promise contains all the headers
     * that pertain to a server-initiated request, and a {@code promisedStreamId} to which response
     * frames will be delivered. Push promise frames are sent as a part of the response to {@code
     * streamId}.
     *
     * @param streamId client-initiated stream ID.  Must be an odd number.
     * @param promisedStreamId server-initiated stream ID.  Must be an even number.
     * @param requestHeaders minimally includes {@code :method}, {@code :scheme}, {@code
     * :authority}, and (@code :path}.
     */
    void pushPromise(int streamId, int promisedStreamId, List<Header> requestHeaders)
        throws IOException;

    /**
     * HTTP/2 only. Expresses that resources for the connection or a client- initiated stream are
     * available from a different network location or protocol configuration.
     *
     * <p>See <a href="http://tools.ietf.org/html/draft-ietf-httpbis-alt-svc-01">alt-svc</a>
     *
     * @param streamId when a client-initiated stream ID (odd number), the origin of this alternate
     * service is the origin of the stream. When zero, the origin is specified in the {@code origin}
     * parameter.
     * @param origin when present, the <a href="http://tools.ietf.org/html/rfc6454">origin</a> is
     * typically represented as a combination of scheme, host and port. When empty, the origin is
     * that of the {@code streamId}.
     * @param protocol an ALPN protocol, such as {@code h2}.
     * @param host an IP address or hostname.
     * @param port the IP port associated with the service.
     * @param maxAge time in seconds that this alternative is considered fresh.
     */
    void alternateService(int streamId, String origin, ByteString protocol, String host, int port,
                          long maxAge);
  }
}