ok2c commented on code in PR #387: URL: https://github.com/apache/httpcomponents-core/pull/387#discussion_r1102694216
########## httpcore5/src/main/java/org/apache/hc/core5/http/protocol/ViaRequest.java: ########## @@ -0,0 +1,127 @@ +/* + * ==================================================================== + * 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.http.protocol; + +import java.io.IOException; + +import org.apache.hc.core5.annotation.Contract; +import org.apache.hc.core5.annotation.ThreadingBehavior; +import org.apache.hc.core5.http.EntityDetails; +import org.apache.hc.core5.http.HttpHeaders; +import org.apache.hc.core5.http.HttpRequest; +import org.apache.hc.core5.http.HttpRequestInterceptor; +import org.apache.hc.core5.http.HttpVersion; +import org.apache.hc.core5.http.ProtocolException; +import org.apache.hc.core5.http.ProtocolVersion; +import org.apache.hc.core5.net.URIAuthority; +import org.apache.hc.core5.util.Args; + + +/** + * An Apache HttpComponents {@link HttpRequestInterceptor} to add the {@link HttpHeaders#VIA} HTTP + * header to requests. + * <p>The {@link HttpHeaders#VIA} header is used to indicate intermediate protocols and recipients + * between the user agent and the server (on requests) or between the origin server and the client + * (on responses). It can be used for tracking message forwards, avoiding request loops, and + * identifying the protocol capabilities of senders along the request/response chain. Each member of + * the {@link HttpHeaders#VIA} header field value represents a proxy or gateway that has forwarded + * the message. + * <p>A proxy <b>MUST</b> send an appropriate {@link HttpHeaders#VIA} header field, as described + * in + * the HTTP specification, in each message that it forwards. An HTTP-to-HTTP gateway <b>MUST</b> + * send an appropriate {@link HttpHeaders#VIA} header field in each inbound request message and + * <b>MAY</b> send a {@link HttpHeaders#VIA} header field in forwarded response messages. + * <p>This interceptor ensures that the {@link HttpHeaders#VIA} header is added to the request + * only + * if it has not been added previously, as per the HTTP specification. Additionally, it updates the + * values in the {@link HttpHeaders#VIA} header correctly in case of multiple intermediate protocols + * or recipients, by appending its own information about how the message was received to the end of + * the header field value. + * + * @since 5.3 + */ +@Contract(threading = ThreadingBehavior.IMMUTABLE) +public class ViaRequest implements HttpRequestInterceptor { + + + /** + * Singleton instance. + */ + public static final HttpRequestInterceptor INSTANCE = new ViaRequest(); + + /** + * Constructs a new {@code ViaRequest}. + */ + public ViaRequest() { + } + + /** + * Adds the HTTP {@link HttpHeaders#VIA} header to the request if it does not already exist. + * + * <p>This method ensures that the version of the request is HTTP/1.1 or higher, and adds the + * Via header in the format {@code <protocol> <version> <host>}, where {@code <protocol>} is the protocol name, + * {@code <version>} is the major and minor version of the request, and {@code <host>} is the value of the Host header. + * + * <p>In case the {@link HttpHeaders#VIA} header already exists, this method updates its value by appending + * the new protocol information in the same format. + * + * <p>If the version of the request is lower than {@code HTTP/1.1} or the request authority not being specified, + * this method throws a {@link ProtocolException}. + * + * @param request the request object to modify + * @param entity the entity for the request, may be {@code null} + * @param context the context for the request + * @throws ProtocolException if there was a protocol error, such as the request version being lower than {@code HTTP/1.1}, + * or the request authority not being specified + * @throws IOException if there was an I/O error + */ + @Override + public void process(final HttpRequest request, final EntityDetails entity, final HttpContext context) throws ProtocolException, IOException { + Args.notNull(request, "HTTP request"); + Args.notNull(context, "HTTP context"); + final ProtocolVersion ver = context.getProtocolVersion() != null ? context.getProtocolVersion() : HttpVersion.HTTP_1_1; + + final URIAuthority authority = request.getAuthority(); + if (authority == null) { + throw new ProtocolException("Request authority not specified"); + } + + + if (!ver.greaterEquals(HttpVersion.HTTP_1_1)) { + throw new ProtocolException("Invalid protocol version: %s", ver); + } + String viaHeaderValue = ver.getProtocol() + " " + ver.getMajor() + "." + ver.getMinor() + " " + authority.getHostName(); + final int port = authority.getPort(); + if (port != -1) { + viaHeaderValue += ":" + port; + } + if (!request.containsHeader(HttpHeaders.VIA)) { Review Comment: @arturobernalg One last thing. Please move the `Via` header value generation into this if statement. There is not point going through the whole process just to find out the value is not needed after all. -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected] --------------------------------------------------------------------- To unsubscribe, e-mail: [email protected] For additional commands, e-mail: [email protected]
