Introduce DefaultMultipartMessageReader

This commit introduces the DefaultMultipartMessageReader, a fully
reactive multipart parser that does have any third party dependencies.

Closes gh-21659

spring-web/src/test/java/org/springframework/http/codec/multipart/DefaultMultipartMessageReaderTests.java

@@ -0,0 +1,177 @@
+/*
+ * Copyright 2002-2019 the original author or authors.
+ *
+ * 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
+ *
+ *      https://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 org.springframework.http.codec.multipart;
+
+import java.io.IOException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.concurrent.CountDownLatch;
+
+import org.junit.Test;
+import reactor.core.publisher.Flux;
+import reactor.test.StepVerifier;
+
+import org.springframework.core.io.ClassPathResource;
+import org.springframework.core.io.Resource;
+import org.springframework.core.io.buffer.AbstractDataBufferAllocatingTestCase;
+import org.springframework.core.io.buffer.DataBuffer;
+import org.springframework.core.io.buffer.DataBufferUtils;
+import org.springframework.http.MediaType;
+import org.springframework.mock.http.server.reactive.test.MockServerHttpRequest;
+
+import static java.util.Collections.emptyMap;
+import static java.util.Collections.singletonMap;
+import static org.junit.Assert.*;
+import static org.springframework.core.ResolvableType.forClass;
+
+/**
+ * @author Arjen Poutsma
+ */
+public class DefaultMultipartMessageReaderTests extends AbstractDataBufferAllocatingTestCase {
+
+	private static final String LOREM_IPSUM = "Lorem ipsum dolor sit amet, consectetur adipiscing elit. Integer iaculis metus id vestibulum nullam.";
+
+	private static final String MUSPI_MEROL = new StringBuilder(LOREM_IPSUM).reverse().toString();
+
+	private static final int BUFFER_SIZE = 16;
+
+	private final DefaultMultipartMessageReader reader = new DefaultMultipartMessageReader();
+
+	@Test
+	public void canRead() {
+		assertTrue(this.reader.canRead(forClass(Part.class), MediaType.MULTIPART_FORM_DATA));
+	}
+
+	@Test
+	public void partNoHeader() {
+		MockServerHttpRequest request = createRequest(
+				new ClassPathResource("part-no-header.multipart", getClass()), "boundary");
+
+		Flux<Part> result = this.reader.read(forClass(Part.class), request, emptyMap());
+
+		StepVerifier.create(result)
+				.consumeNextWith(part -> {
+					assertTrue(part.headers().isEmpty());
+					part.content().subscribe(DataBufferUtils::release);
+				})
+				.verifyComplete();
+	}
+
+	@Test
+	public void partNoEndBoundary() {
+		MockServerHttpRequest request = createRequest(
+				new ClassPathResource("part-no-end-boundary.multipart", getClass()), "boundary");
+
+		Flux<Part> result = this.reader.read(forClass(Part.class), request, emptyMap());
+
+		StepVerifier.create(result)
+				.consumeNextWith(part -> {
+					part.content().subscribe(DataBufferUtils::release);
+				})
+				.verifyComplete();
+	}
+
+	@Test
+	public void firefox() {
+		testBrowser(new ClassPathResource("firefox.multipart", getClass()),
+				"---------------------------18399284482060392383840973206");
+	}
+
+	@Test
+	public void chrome() {
+		testBrowser(new ClassPathResource("chrome.multipart", getClass()),
+				"----WebKitFormBoundaryEveBLvRT65n21fwU");
+	}
+
+	@Test
+	public void safari() {
+		testBrowser(new ClassPathResource("safari.multipart", getClass()),
+				"----WebKitFormBoundaryG8fJ50opQOML0oGD");
+	}
+
+	private void testBrowser(Resource resource, String boundary) {
+		MockServerHttpRequest request = createRequest(resource, boundary);
+
+		Flux<Part> result = this.reader.read(forClass(Part.class), request, emptyMap());
+
+		StepVerifier.create(result)
+				.consumeNextWith(part -> testBrowserFormField(part, "text1", "a"))
+				.consumeNextWith(part -> testBrowserFormField(part, "text2", "b"))
+				.consumeNextWith(part -> testBrowserFile(part, "file1", "a.txt", LOREM_IPSUM))
+				.consumeNextWith(part -> testBrowserFile(part, "file2", "a.txt", LOREM_IPSUM))
+				.consumeNextWith(part -> testBrowserFile(part, "file2", "b.txt", MUSPI_MEROL))
+				.verifyComplete();
+	}
+
+	private MockServerHttpRequest createRequest(Resource resource, String boundary) {
+		Flux<DataBuffer> body = DataBufferUtils
+				.readByteChannel(resource::readableChannel, this.bufferFactory, BUFFER_SIZE);
+
+		MediaType contentType = new MediaType("multipart", "form-data", singletonMap("boundary", boundary));
+		return MockServerHttpRequest.post("/")
+				.contentType(contentType)
+				.body(body);
+	}
+
+	private static void testBrowserFormField(Part part, String name, String value) {
+		assertTrue(part instanceof FormFieldPart);
+		assertEquals(name, part.name());
+		FormFieldPart formField = (FormFieldPart) part;
+		assertEquals(value, formField.value());
+	}
+
+	private static void testBrowserFile(Part part, String name, String filename, String contents) {
+		try {
+			assertTrue(part instanceof FilePart);
+			assertEquals(name, part.name());
+			FilePart file = (FilePart) part;
+			assertEquals(filename, file.filename());
+
+			Path tempFile = Files.createTempFile("DefaultMultipartMessageReaderTests", null);
+
+			CountDownLatch latch = new CountDownLatch(1);
+			file.transferTo(tempFile)
+					.subscribe(null,
+							throwable -> fail(throwable.getMessage()),
+							() -> {
+								try {
+									verifyContents(tempFile, contents);
+								}
+								finally {
+									latch.countDown();
+								}
+
+							});
+
+			latch.await();
+		}
+		catch (Exception ex) {
+			throw new AssertionError(ex);
+		}
+	}
+
+	private static void verifyContents(Path tempFile, String contents) {
+		try {
+			String result = String.join("", Files.readAllLines(tempFile));
+			assertEquals(contents, result);
+		}
+		catch (IOException ex) {
+			throw new AssertionError(ex);
+		}
+	}
+
+}