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Add RFC 7639 ALPN header codec; emit ALPN on CONNECT tunnels
Encode protocol IDs with core's PercentCodec.HTTP_TOKEN (canonical RFC 7230 tchar form, uppercase hex) and decode strictly, rejecting malformed percent-encoding with ProtocolException. Configure via ConnectAlpnProvider through setConnectAlpnProvider on the classic and async builders; ConnectExec/AsyncConnectExec emit the header when a provider is set. Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
1 parent afba680 commit 36079e1

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Lines changed: 695 additions & 37 deletions

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‎httpclient5/src/main/java/org/apache/hc/client5/http/ConnectAlpnProvider.java‎

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/*
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* ====================================================================
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*
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*/
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package org.apache.hc.client5.http;
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import java.util.List;
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import org.apache.hc.core5.http.HttpHost;
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/**
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* Supplies the Application-Layer Protocol Negotiation (ALPN) protocol IDs
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* to advertise in the HTTP {@code ALPN} header on a {@code CONNECT} request
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* (RFC 7639).
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*
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* <p>If this method returns {@code null} or an empty list, the client will
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* not add the {@code ALPN} header.</p>
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*
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* <p>Implementations should be fast and side-effect free; it may be invoked
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* for each CONNECT attempt.</p>
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*
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* @since 5.6
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*/
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@FunctionalInterface
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public interface ConnectAlpnProvider {
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/**
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* Returns the ALPN protocol IDs to advertise for a tunnel to {@code target}
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* over the given {@code route}.
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*
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* @param target the origin server the tunnel will connect to (non-null)
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* @param route the planned connection route, including proxy info (non-null)
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* @return list of protocol IDs (e.g., {@code "h2"}, {@code "http/1.1"});
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* {@code null} or empty to omit the header
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*/
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List<String> getAlpnForTunnel(HttpHost target, HttpRoute route);
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}

‎httpclient5/src/main/java/org/apache/hc/client5/http/impl/AlpnHeaderSupport.java‎

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/*
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* ====================================================================
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* Licensed to the Apache Software Foundation (ASF) under one
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* or more contributor license agreements. See the NOTICE file
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* distributed with this work for additional information
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* regarding copyright ownership. The ASF licenses this file
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* to you under the Apache License, Version 2.0 (the
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* "License"); you may not use this file except in compliance
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* with the License. You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing,
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* software distributed under the License is distributed on an
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* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
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* KIND, either express or implied. See the License for the
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* specific language governing permissions and limitations
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* under the License.
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* ====================================================================
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*
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* This software consists of voluntary contributions made by many
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* individuals on behalf of the Apache Software Foundation. For more
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* information on the Apache Software Foundation, please see
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* <http://www.apache.org/>.
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*
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*/
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package org.apache.hc.client5.http.impl;
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import java.nio.charset.StandardCharsets;
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import java.util.ArrayList;
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import java.util.List;
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import org.apache.hc.core5.annotation.Contract;
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import org.apache.hc.core5.annotation.Internal;
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import org.apache.hc.core5.annotation.ThreadingBehavior;
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import org.apache.hc.core5.http.Header;
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import org.apache.hc.core5.http.HttpHeaders;
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import org.apache.hc.core5.http.ProtocolException;
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import org.apache.hc.core5.http.message.MessageSupport;
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import org.apache.hc.core5.net.PercentCodec;
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import org.apache.hc.core5.util.Args;
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/**
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* Codec for the HTTP {@code ALPN} header field (RFC 7639).
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*
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* @since 5.7
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*/
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@Contract(threading = ThreadingBehavior.IMMUTABLE)
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@Internal
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public final class AlpnHeaderSupport {
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private AlpnHeaderSupport() {
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}
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/**
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* Formats a list of raw ALPN protocol IDs into a single {@code ALPN} header.
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*/
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public static Header formatValue(final List<String> protocolIds) {
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Args.notEmpty(protocolIds, "protocolIds");
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return MessageSupport.headerOfTokens(HttpHeaders.ALPN, protocolIds, AlpnHeaderSupport::encodeId);
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}
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/**
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* Parses an {@code ALPN} header into decoded protocol IDs.
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*
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* @throws ProtocolException if a token is not a well-formed percent-encoded protocol ID.
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*/
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public static List<String> parseValue(final Header header) throws ProtocolException {
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final List<String> tokens = new ArrayList<>();
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MessageSupport.parseTokens(header, tokens::add);
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final List<String> out = new ArrayList<>(tokens.size());
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for (final String token : tokens) {
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out.add(decodeId(token));
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}
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return out;
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}
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/**
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* Encodes a single raw protocol ID to canonical token form using the HTTP token codec
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* from core, which keeps RFC 7230 {@code tchar} octets literal and percent-encodes the
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* rest (including {@code '%'}) with uppercase hexadecimal.
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*/
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public static String encodeId(final String id) {
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Args.notBlank(id, "id");
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return PercentCodec.HTTP_TOKEN.encode(id);
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}
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/**
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* Decodes a percent-encoded token to a raw protocol ID using UTF-8.
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* <p>
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* A {@code '%'} that is not followed by two hexadecimal digits is a malformed
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* token and is rejected as a protocol error.
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*
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* @throws ProtocolException if the token contains malformed percent-encoding.
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*/
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public static String decodeId(final String token) throws ProtocolException {
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Args.notBlank(token, "token");
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for (int i = 0; i < token.length(); i++) {
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if (token.charAt(i) == '%') {
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if (i + 2 >= token.length()
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|| Character.digit(token.charAt(i + 1), 16) < 0
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|| Character.digit(token.charAt(i + 2), 16) < 0) {
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throw new ProtocolException("Malformed percent-encoding in ALPN protocol id: " + token);
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}
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i += 2;
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}
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}
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return PercentCodec.decode(token, StandardCharsets.UTF_8);
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}
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}

‎httpclient5/src/main/java/org/apache/hc/client5/http/impl/async/AsyncConnectExec.java‎

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import java.util.concurrent.atomic.AtomicReference;
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import org.apache.hc.client5.http.AuthenticationStrategy;
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import org.apache.hc.client5.http.ConnectAlpnProvider;
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import org.apache.hc.client5.http.EndpointInfo;
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import org.apache.hc.client5.http.HttpRoute;
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import org.apache.hc.client5.http.RouteTracker;
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import org.apache.hc.client5.http.auth.ChallengeType;
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import org.apache.hc.client5.http.auth.MalformedChallengeException;
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import org.apache.hc.client5.http.config.RequestConfig;
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import org.apache.hc.client5.http.impl.AlpnHeaderSupport;
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import org.apache.hc.client5.http.impl.auth.AuthCacheKeeper;
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import org.apache.hc.client5.http.impl.auth.AuthenticationHandler;
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import org.apache.hc.client5.http.impl.routing.BasicRouteDirector;
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private final AuthCacheKeeper authCacheKeeper;
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private final HttpRouteDirector routeDirector;
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private final ConnectAlpnProvider alpnProvider;
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public AsyncConnectExec(
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final HttpProcessor proxyHttpProcessor,
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final AuthenticationStrategy proxyAuthStrategy,
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final SchemePortResolver schemePortResolver,
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final boolean authCachingDisabled) {
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this(proxyHttpProcessor, proxyAuthStrategy, schemePortResolver, authCachingDisabled, null);
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}
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public AsyncConnectExec(
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final HttpProcessor proxyHttpProcessor,
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final AuthenticationStrategy proxyAuthStrategy,
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final SchemePortResolver schemePortResolver,
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final boolean authCachingDisabled,
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final ConnectAlpnProvider alpnProvider) {
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Args.notNull(proxyHttpProcessor, "Proxy HTTP processor");
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Args.notNull(proxyAuthStrategy, "Proxy authentication strategy");
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this.proxyHttpProcessor = proxyHttpProcessor;
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this.proxyAuthStrategy = proxyAuthStrategy;
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this.authenticator = new AuthenticationHandler();
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this.authCacheKeeper = authCachingDisabled ? null : new AuthCacheKeeper(schemePortResolver);
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this.routeDirector = BasicRouteDirector.INSTANCE;
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this.alpnProvider = alpnProvider;
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}
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static class State {
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if (LOG.isDebugEnabled()) {
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LOG.debug("{} create tunnel", exchangeId);
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}
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createTunnel(state, proxy, target, scope, new AsyncExecCallback() {
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createTunnel(state, proxy, target, route, scope, new AsyncExecCallback() {
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@Override
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public AsyncDataConsumer handleResponse(final HttpResponse response, final EntityDetails entityDetails) throws HttpException, IOException {
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final State state,
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final HttpHost proxy,
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final HttpHost nextHop,
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final HttpRoute route,
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final AsyncExecChain.Scope scope,
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final AsyncExecCallback asyncExecCallback) {
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final HttpRequest connect = new BasicHttpRequest(Method.CONNECT, nextHop, nextHop.toHostString());
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connect.setVersion(HttpVersion.HTTP_1_1);
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// --- RFC 7639: inject ALPN header (if provided) ----------------
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if (alpnProvider != null) {
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final List<String> alpn = alpnProvider.getAlpnForTunnel(nextHop, route);
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if (alpn != null && !alpn.isEmpty()) {
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connect.setHeader(AlpnHeaderSupport.formatValue(alpn));
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}
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}
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proxyHttpProcessor.process(connect, null, clientContext);
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authenticator.addAuthResponse(proxy, ChallengeType.PROXY, connect, proxyAuthExchange, clientContext);
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‎httpclient5/src/main/java/org/apache/hc/client5/http/impl/async/HttpAsyncClientBuilder.java‎

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import java.util.function.UnaryOperator;
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import org.apache.hc.client5.http.AuthenticationStrategy;
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import org.apache.hc.client5.http.ConnectAlpnProvider;
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import org.apache.hc.client5.http.ConnectionKeepAliveStrategy;
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import org.apache.hc.client5.http.EarlyHintsListener;
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import org.apache.hc.client5.http.HttpRequestRetryStrategy;
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private boolean tlsRequired;
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private ConnectAlpnProvider connectAlpnProvider;
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/**
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* Maps {@code Content-Encoding} tokens to decoder factories in insertion order.
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*/
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return this;
937940
}
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/**
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* Sets the {@link ConnectAlpnProvider} used to populate the {@code ALPN} header
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* (RFC 7639) on {@code CONNECT} requests when establishing an HTTP tunnel through a proxy.
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*
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* @param connectAlpnProvider the provider, or {@code null} to not send an {@code ALPN} header.
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* @return this builder.
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* @since 5.7
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*/
950+
public HttpAsyncClientBuilder setConnectAlpnProvider(final ConnectAlpnProvider connectAlpnProvider) {
951+
this.connectAlpnProvider = connectAlpnProvider;
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return this;
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}
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/**
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* Registers a global {@link org.apache.hc.client5.http.EarlyHintsListener}
941957
* that will be notified when the client receives {@code 103 Early Hints}
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new DefaultHttpProcessor(new RequestTargetHost(), new RequestUserAgent(userAgentCopy)),
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proxyAuthStrategyCopy,
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schemePortResolver != null ? schemePortResolver : DefaultSchemePortResolver.INSTANCE,
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authCachingDisabled),
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authCachingDisabled,
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connectAlpnProvider),
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ChainElement.CONNECT.name());
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if (earlyHintsListener != null) {

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