Add HTTP/2 CONNECT tunnel support over HTTP/2 proxy connections. Implements multiplexing-safe CONNECT tunneling by adapting a single HTTP/2 proxy stream to a ProtocolIOSession that can be upgraded with TLS and an optional protocol handler. T

Author: arturobernalg

httpcore5-h2/src/main/java/org/apache/hc/core5/http2/nio/support/H2OverH2TunnelExchangeHandler.java

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+/*
+ * ====================================================================
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF 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.
+ * ====================================================================
+ *
+ * This software consists of voluntary contributions made by many
+ * individuals on behalf of the Apache Software Foundation.  For more
+ * information on the Apache Software Foundation, please see
+ * <http://www.apache.org/>.
+ *
+ */
+package org.apache.hc.core5.http2.nio.support;
+
+import java.io.IOException;
+import java.nio.ByteBuffer;
+import java.util.List;
+import java.util.concurrent.atomic.AtomicBoolean;
+
+import org.apache.hc.core5.concurrent.FutureCallback;
+import org.apache.hc.core5.http.ConnectionClosedException;
+import org.apache.hc.core5.http.EntityDetails;
+import org.apache.hc.core5.http.Header;
+import org.apache.hc.core5.http.HttpException;
+import org.apache.hc.core5.http.HttpRequest;
+import org.apache.hc.core5.http.HttpResponse;
+import org.apache.hc.core5.http.Method;
+import org.apache.hc.core5.http.StreamControl;
+import org.apache.hc.core5.http.impl.BasicEntityDetails;
+import org.apache.hc.core5.http.message.BasicHttpRequest;
+import org.apache.hc.core5.http.message.StatusLine;
+import org.apache.hc.core5.http.nio.AsyncClientExchangeHandler;
+import org.apache.hc.core5.http.nio.CapacityChannel;
+import org.apache.hc.core5.http.nio.DataStreamChannel;
+import org.apache.hc.core5.http.nio.RequestChannel;
+import org.apache.hc.core5.http.nio.ssl.TlsStrategy;
+import org.apache.hc.core5.http.protocol.HttpContext;
+import org.apache.hc.core5.io.CloseMode;
+import org.apache.hc.core5.net.NamedEndpoint;
+import org.apache.hc.core5.net.URIAuthority;
+import org.apache.hc.core5.reactor.IOEventHandler;
+import org.apache.hc.core5.reactor.IOEventHandlerFactory;
+import org.apache.hc.core5.reactor.IOSession;
+import org.apache.hc.core5.reactor.ProtocolIOSession;
+import org.apache.hc.core5.reactor.ssl.TransportSecurityLayer;
+import org.apache.hc.core5.util.Timeout;
+
+/**
+ * Exchange handler that establishes CONNECT and then exposes the tunnel stream as a ProtocolIOSession.
+ */
+final class H2OverH2TunnelExchangeHandler implements AsyncClientExchangeHandler {
+
+    private final IOSession physicalSession;
+    private final NamedEndpoint targetEndpoint;
+    private final Timeout connectTimeout;
+    private final boolean secure;
+    private final TlsStrategy tlsStrategy;
+    private final IOEventHandlerFactory protocolStarter;
+    private final FutureCallback<ProtocolIOSession> callback;
+
+    private final AtomicBoolean done;
+
+    private volatile DataStreamChannel dataChannel;
+    private volatile CapacityChannel capacityChannel;
+    private volatile StreamControl streamControl;
+    private volatile H2TunnelProtocolIOSession tunnelSession;
+
+    H2OverH2TunnelExchangeHandler(
+            final IOSession physicalSession,
+            final NamedEndpoint targetEndpoint,
+            final Timeout connectTimeout,
+            final boolean secure,
+            final TlsStrategy tlsStrategy,
+            final IOEventHandlerFactory protocolStarter,
+            final FutureCallback<ProtocolIOSession> callback) {
+        this.physicalSession = physicalSession;
+        this.targetEndpoint = targetEndpoint;
+        this.connectTimeout = connectTimeout;
+        this.secure = secure;
+        this.tlsStrategy = tlsStrategy;
+        this.protocolStarter = protocolStarter;
+        this.callback = callback;
+        this.done = new AtomicBoolean(false);
+    }
+
+    void initiated(final StreamControl streamControl) {
+        this.streamControl = streamControl;
+        final H2TunnelProtocolIOSession tunnel = this.tunnelSession;
+        if (tunnel != null) {
+            tunnel.bindStreamControl(streamControl);
+        }
+    }
+
+    @Override
+    public void releaseResources() {
+    }
+
+    @Override
+    public void failed(final Exception cause) {
+        fail(cause);
+    }
+
+    @Override
+    public void cancel() {
+        fail(new ConnectionClosedException("Tunnel setup cancelled"));
+    }
+
+    @Override
+    public void produceRequest(final RequestChannel requestChannel, final HttpContext context) throws HttpException, IOException {
+        final HttpRequest connectRequest = new BasicHttpRequest(Method.CONNECT.name(), (String) null);
+        connectRequest.setAuthority(new URIAuthority(targetEndpoint));
+        requestChannel.sendRequest(connectRequest, new BasicEntityDetails(-1, null), context);
+    }
+
+    @Override
+    public int available() {
+        final H2TunnelProtocolIOSession tunnel = this.tunnelSession;
+        return tunnel != null ? tunnel.available() : 0;
+    }
+
+    @Override
+    public void produce(final DataStreamChannel channel) throws IOException {
+        this.dataChannel = channel;
+        final H2TunnelProtocolIOSession tunnel = this.tunnelSession;
+        if (tunnel != null) {
+            tunnel.attachChannel(channel);
+            tunnel.onOutputReady();
+        }
+    }
+
+    @Override
+    public void consumeInformation(final HttpResponse response, final HttpContext context) {
+    }
+
+    @Override
+    public void consumeResponse(
+            final HttpResponse response,
+            final EntityDetails entityDetails,
+            final HttpContext context) throws HttpException, IOException {
+
+        final int status = response.getCode();
+        if (status < 200 || status >= 300) {
+            throw new HttpException("Tunnel refused: " + new StatusLine(response));
+        }
+
+        if (entityDetails == null) {
+            throw new HttpException("CONNECT response does not provide a tunneled data stream");
+        }
+
+        if (this.tunnelSession != null) {
+            return;
+        }
+
+        final H2TunnelProtocolIOSession tunnel =
+                new H2TunnelProtocolIOSession(physicalSession, targetEndpoint, connectTimeout, streamControl);
+
+        final DataStreamChannel currentChannel = this.dataChannel;
+        if (currentChannel != null) {
+            tunnel.attachChannel(currentChannel);
+        }
+        final CapacityChannel currentCapacity = this.capacityChannel;
+        if (currentCapacity != null) {
+            tunnel.updateCapacityChannel(currentCapacity);
+        }
+        this.tunnelSession = tunnel;
+
+        if (secure) {
+            tlsStrategy.upgrade(
+                    tunnel,
+                    targetEndpoint,
+                    null,
+                    connectTimeout,
+                    new FutureCallback<TransportSecurityLayer>() {
+
+                        @Override
+                        public void completed(final TransportSecurityLayer transportSecurityLayer) {
+                            try {
+                                startProtocol(tunnel);
+                                complete(tunnel);
+                            } catch (final Exception ex) {
+                                fail(ex);
+                            }
+                        }
+
+                        @Override
+                        public void failed(final Exception ex) {
+                            fail(ex);
+                        }
+
+                        @Override
+                        public void cancelled() {
+                            fail(new ConnectionClosedException("Tunnel TLS upgrade cancelled"));
+                        }
+                    });
+        } else {
+            startProtocol(tunnel);
+            complete(tunnel);
+        }
+    }
+
+    private void startProtocol(final H2TunnelProtocolIOSession tunnel) throws IOException {
+        if (protocolStarter == null) {
+            return;
+        }
+        final IOEventHandler protocolHandler = protocolStarter.createHandler(tunnel, null);
+        tunnel.upgrade(protocolHandler);
+        protocolHandler.connected(tunnel);
+    }
+
+    @Override
+    public void updateCapacity(final CapacityChannel capacityChannel) throws IOException {
+        this.capacityChannel = capacityChannel;
+        final H2TunnelProtocolIOSession tunnel = this.tunnelSession;
+        if (tunnel != null) {
+            tunnel.updateCapacityChannel(capacityChannel);
+        }
+    }
+
+    @Override
+    public void consume(final ByteBuffer src) throws IOException {
+        final H2TunnelProtocolIOSession tunnel = this.tunnelSession;
+        if (tunnel != null && src != null && src.hasRemaining()) {
+            tunnel.onInput(src);
+        }
+    }
+
+    @Override
+    public void streamEnd(final List<? extends Header> trailers) {
+        final H2TunnelProtocolIOSession tunnel = this.tunnelSession;
+        if (tunnel != null) {
+            tunnel.onRemoteStreamEnd();
+        } else {
+            closeTransport(CloseMode.GRACEFUL);
+        }
+        if (done.compareAndSet(false, true) && callback != null) {
+            callback.failed(new ConnectionClosedException("Tunnel stream closed"));
+        }
+    }
+
+    private void closeTransport(final CloseMode closeMode) {
+        final H2TunnelProtocolIOSession tunnel = this.tunnelSession;
+        if (tunnel != null) {
+            tunnel.close(closeMode);
+            return;
+        }
+        final StreamControl currentStreamControl = this.streamControl;
+        if (currentStreamControl != null) {
+            currentStreamControl.cancel();
+        }
+    }
+
+    private void fail(final Exception cause) {
+        closeTransport(CloseMode.IMMEDIATE);
+        if (done.compareAndSet(false, true) && callback != null) {
+            callback.failed(cause);
+        }
+    }
+
+    private void complete(final H2TunnelProtocolIOSession tunnel) {
+        if (done.compareAndSet(false, true) && callback != null) {
+            callback.completed(tunnel);
+        }
+    }
+}