001/*
002 * Copyright 2002-2020 the original author or authors.
003 *
004 * Licensed under the Apache License, Version 2.0 (the "License");
005 * you may not use this file except in compliance with the License.
006 * You may obtain a copy of the License at
007 *
008 *      https://www.apache.org/licenses/LICENSE-2.0
009 *
010 * Unless required by applicable law or agreed to in writing, software
011 * distributed under the License is distributed on an "AS IS" BASIS,
012 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
013 * See the License for the specific language governing permissions and
014 * limitations under the License.
015 */
016
017package org.springframework.http.server.reactive;
018
019import org.reactivestreams.Publisher;
020import reactor.core.publisher.Flux;
021import reactor.core.publisher.Mono;
022
023import org.springframework.core.io.buffer.DataBuffer;
024import org.springframework.core.io.buffer.DataBufferUtils;
025import org.springframework.http.HttpHeaders;
026
027/**
028 * {@link ServerHttpResponse} decorator for HTTP HEAD requests.
029 *
030 * @author Rossen Stoyanchev
031 * @since 5.0
032 */
033public class HttpHeadResponseDecorator extends ServerHttpResponseDecorator {
034
035
036        public HttpHeadResponseDecorator(ServerHttpResponse delegate) {
037                super(delegate);
038        }
039
040
041        /**
042         * Consume and release the body without writing.
043         * <p>If the headers contain neither Content-Length nor Transfer-Encoding,
044         * count the bytes and set Content-Length.
045         */
046        @Override
047        public final Mono<Void> writeWith(Publisher<? extends DataBuffer> body) {
048                if (shouldSetContentLength()) {
049                        return Flux.from(body)
050                                        .reduce(0, (current, buffer) -> {
051                                                int next = current + buffer.readableByteCount();
052                                                DataBufferUtils.release(buffer);
053                                                return next;
054                                        })
055                                        .doOnNext(length -> getHeaders().setContentLength(length))
056                                        .then();
057                }
058                else {
059                        return Flux.from(body)
060                                        .doOnNext(DataBufferUtils::release)
061                                        .then();
062                }
063        }
064
065        private boolean shouldSetContentLength() {
066                return (getHeaders().getFirst(HttpHeaders.CONTENT_LENGTH) == null &&
067                                getHeaders().getFirst(HttpHeaders.TRANSFER_ENCODING) == null);
068        }
069
070        /**
071         * Invoke {@link #setComplete()} without writing.
072         * <p>RFC 7302 allows HTTP HEAD response without content-length and it's not
073         * something that can be computed on a streaming response.
074         */
075        @Override
076        public final Mono<Void> writeAndFlushWith(Publisher<? extends Publisher<? extends DataBuffer>> body) {
077                // Not feasible to count bytes on potentially streaming response.
078                // RFC 7302 allows HEAD without content-length.
079                return setComplete();
080        }
081
082}