Skip 'Expect: 100-continue' header for zero-length S3 streaming requests

.changes/next-release/bugfix-AmazonS3-bb097c9.json

@@ -0,0 +1,6 @@
+{
+    "type": "bugfix",
+    "category": "Amazon S3",
+    "contributor": "",
+    "description": "Fix StreamingRequestInterceptor to skip Expect: 100-continue header when PutObject or UploadPart requests have zero content length."
+}

services/s3/src/main/java/software/amazon/awssdk/services/s3/internal/handlers/StreamingRequestInterceptor.java

@@ -15,6 +15,7 @@
 
 package software.amazon.awssdk.services.s3.internal.handlers;
 
+import java.util.Optional;
 import software.amazon.awssdk.annotations.SdkInternalApi;
 import software.amazon.awssdk.core.interceptor.Context;
 import software.amazon.awssdk.core.interceptor.ExecutionAttributes;
@@ -29,12 +30,42 @@
 @SdkInternalApi
 //TODO: This should be generalized for all streaming requests
 public final class StreamingRequestInterceptor implements ExecutionInterceptor {
+
+    private static final String DECODED_CONTENT_LENGTH_HEADER = "x-amz-decoded-content-length";
+    private static final String CONTENT_LENGTH_HEADER = "Content-Length";
+
     @Override
     public SdkHttpRequest modifyHttpRequest(Context.ModifyHttpRequest context,
                                             ExecutionAttributes executionAttributes) {
-        if (context.request() instanceof PutObjectRequest || context.request() instanceof UploadPartRequest) {
+        if (shouldAddExpectContinueHeader(context)) {
             return context.httpRequest().toBuilder().putHeader("Expect", "100-continue").build();
         }
         return context.httpRequest();
     }
+
+    private boolean shouldAddExpectContinueHeader(Context.ModifyHttpRequest context) {
+        // Only applies to streaming operations
+        if (!(context.request() instanceof PutObjectRequest
+              || context.request() instanceof UploadPartRequest)) {
+            return false;
+        }
+        return getContentLengthHeader(context.httpRequest())
+            .map(Long::parseLong)
+            .map(length -> length != 0L)
+            .orElse(true);
+    }
+
+    /**
+     * Retrieves content length header value.
+     * Checks x-amz-decoded-content-length first, then falls back to Content-Length.
+     *
+     * @param httpRequest the HTTP request
+     * @return Optional containing the content length header value, or empty if not present
+     */
+    private Optional<String> getContentLengthHeader(SdkHttpRequest httpRequest) {
+        Optional<String> decodedLength = httpRequest.firstMatchingHeader(DECODED_CONTENT_LENGTH_HEADER);
+        return decodedLength.isPresent()
+               ? decodedLength
+               : httpRequest.firstMatchingHeader(CONTENT_LENGTH_HEADER);
+    }
 }

services/s3/src/test/java/software/amazon/awssdk/services/s3/functionaltests/Expect100ContinueHeaderTest.java

@@ -0,0 +1,327 @@
+/*
+ * Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License").
+ * You may not use this file except in compliance with the License.
+ * A copy of the License is located at
+ *
+ *  http://aws.amazon.com/apache2.0
+ *
+ * or in the "license" file accompanying this file. This file 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 software.amazon.awssdk.services.s3.functionaltests;
+
+import static com.github.tomakehurst.wiremock.client.WireMock.aResponse;
+import static com.github.tomakehurst.wiremock.client.WireMock.anyUrl;
+import static com.github.tomakehurst.wiremock.client.WireMock.findAll;
+import static com.github.tomakehurst.wiremock.client.WireMock.put;
+import static com.github.tomakehurst.wiremock.client.WireMock.putRequestedFor;
+import static com.github.tomakehurst.wiremock.client.WireMock.stubFor;
+import static org.assertj.core.api.Assertions.assertThat;
+
+import com.github.tomakehurst.wiremock.junit5.WireMockRuntimeInfo;
+import com.github.tomakehurst.wiremock.junit5.WireMockTest;
+import com.github.tomakehurst.wiremock.verification.LoggedRequest;
+import java.io.ByteArrayInputStream;
+import java.net.URI;
+import java.nio.ByteBuffer;
+import java.nio.charset.StandardCharsets;
+import java.util.List;
+import java.util.concurrent.CompletableFuture;
+import java.util.function.Function;
+import java.util.stream.Stream;
+import org.junit.jupiter.api.AfterEach;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.TestInstance;
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.Arguments;
+import org.junit.jupiter.params.provider.MethodSource;
+import org.reactivestreams.Publisher;
+import org.reactivestreams.Subscription;
+import software.amazon.awssdk.auth.credentials.AwsBasicCredentials;
+import software.amazon.awssdk.auth.credentials.StaticCredentialsProvider;
+import software.amazon.awssdk.core.async.AsyncRequestBody;
+import software.amazon.awssdk.core.checksums.RequestChecksumCalculation;
+import software.amazon.awssdk.core.checksums.ResponseChecksumValidation;
+import software.amazon.awssdk.core.sync.RequestBody;
+import software.amazon.awssdk.http.ContentStreamProvider;
+import software.amazon.awssdk.http.SdkHttpClient;
+import software.amazon.awssdk.http.SdkHttpConfigurationOption;
+import software.amazon.awssdk.http.apache.ApacheHttpClient;
+import software.amazon.awssdk.http.async.SdkAsyncHttpClient;
+import software.amazon.awssdk.http.nio.netty.NettyNioAsyncHttpClient;
+import software.amazon.awssdk.regions.Region;
+import software.amazon.awssdk.services.s3.S3AsyncClient;
+import software.amazon.awssdk.services.s3.S3Client;
+import software.amazon.awssdk.services.s3.model.PutObjectRequest;
+import software.amazon.awssdk.services.s3.model.UploadPartRequest;
+import software.amazon.awssdk.utils.AttributeMap;
+
+/**
+ * Functional tests to verify RFC 9110 compliance for Expect: 100-continue header behavior.
+ * <p>
+ * Per RFC 9110 Section 10.1.1, clients MUST NOT send 100-continue for requests without content.
+ * These tests verify the header is correctly omitted for zero-length bodies and included for
+ * non-empty bodies in both sync and async S3 operations.
+ */
+@WireMockTest(httpsEnabled = true)
+@TestInstance(TestInstance.Lifecycle.PER_CLASS)
+public class Expect100ContinueHeaderTest {
+
+    private static final String BUCKET = "test-bucket";
+    private static final String KEY = "test-key";
+    private static final String UPLOAD_ID = "test-upload-id";
+
+    private S3Client syncClient;
+    private S3AsyncClient asyncClient;
+
+    @BeforeEach
+    void setup(WireMockRuntimeInfo wmRuntimeInfo) {
+        URI endpointOverride = URI.create(wmRuntimeInfo.getHttpsBaseUrl());
+        StaticCredentialsProvider credentialsProvider = StaticCredentialsProvider.create(
+            AwsBasicCredentials.create("akid", "skid"));
+
+        SdkHttpClient apacheHttpClient = ApacheHttpClient.builder()
+                                                         .buildWithDefaults(AttributeMap.builder()
+                                                                                        .put(SdkHttpConfigurationOption.TRUST_ALL_CERTIFICATES, Boolean.TRUE)
+                                                                                        .build());
+
+        syncClient = S3Client.builder()
+                             .httpClient(apacheHttpClient)
+                             .region(Region.US_EAST_1)
+                             .endpointOverride(endpointOverride)
+                             .requestChecksumCalculation(RequestChecksumCalculation.WHEN_REQUIRED)
+                             .responseChecksumValidation(ResponseChecksumValidation.WHEN_REQUIRED)
+                             .forcePathStyle(true)
+                             .credentialsProvider(credentialsProvider)
+                             .build();
+
+        SdkAsyncHttpClient nettyHttpClient = NettyNioAsyncHttpClient.builder()
+                                                                    .buildWithDefaults(AttributeMap.builder()
+                                                                                                   .put(SdkHttpConfigurationOption.TRUST_ALL_CERTIFICATES, Boolean.TRUE)
+                                                                                                   .build());
+
+        asyncClient = S3AsyncClient.builder()
+                                   .httpClient(nettyHttpClient)
+                                   .region(Region.US_EAST_1)
+                                   .endpointOverride(endpointOverride)
+                                   .requestChecksumCalculation(RequestChecksumCalculation.WHEN_REQUIRED)
+                                   .responseChecksumValidation(ResponseChecksumValidation.WHEN_REQUIRED)
+                                   .forcePathStyle(true)
+                                   .credentialsProvider(credentialsProvider)
+                                   .build();
+    }
+
+    @AfterEach
+    void teardown() {
+        if (syncClient != null) {
+            syncClient.close();
+        }
+        if (asyncClient != null) {
+            asyncClient.close();
+        }
+    }
+
+    @ParameterizedTest(name = "{0}_withEmptyBody_doesNotSendExpectHeader")
+    @MethodSource("syncRequestProvider")
+    void syncOperation_withEmptyBody_doesNotSendExpectHeader(String operationType,
+                                                             Function<RequestBody, Void> executeRequest) {
+        stubAnyPutRequest();
+        executeRequest.apply(RequestBody.empty());
+        assertExpectHeaderNotPresent();
+    }
+
+    @ParameterizedTest(name = "{0}_withEmptyStringBody_doesNotSendExpectHeader")
+    @MethodSource("syncRequestProvider")
+    void syncOperation_withEmptyStringBody_doesNotSendExpectHeader(String operationType,
+                                                                   Function<RequestBody, Void> executeRequest) {
+        stubAnyPutRequest();
+        executeRequest.apply(RequestBody.fromString(""));
+        assertExpectHeaderNotPresent();
+    }
+
+    @ParameterizedTest(name = "{0}_withNonEmptyBody_sendsExpectHeader")
+    @MethodSource("syncRequestProvider")
+    void syncOperation_withNonEmptyBody_sendsExpectHeader(String operationType,
+                                                          Function<RequestBody, Void> executeRequest) {
+        stubAnyPutRequest();
+        executeRequest.apply(RequestBody.fromString("test content"));
+        assertExpectHeaderPresent();
+    }
+
+    @ParameterizedTest(name = "{0}_withContentProviderEmptyBody_sendsExpectHeader")
+    @MethodSource("syncRequestProvider")
+    void syncOperation_withContentProviderEmptyBody_sendsExpectHeader(String operationType,
+                                                                      Function<RequestBody, Void> executeRequest) {
+        stubAnyPutRequest();
+        ContentStreamProvider emptyProvider = () -> new ByteArrayInputStream(new byte[0]);
+        RequestBody emptyBody = RequestBody.fromContentProvider(emptyProvider, "application/octet-stream");
+        executeRequest.apply(emptyBody);
+        assertExpectHeaderPresent();
+    }
+
+    @ParameterizedTest(name = "{0}_withContentProviderNonEmptyBody_sendsExpectHeader")
+    @MethodSource("syncRequestProvider")
+    void syncOperation_withContentProviderNonEmptyBody_sendsExpectHeader(String operationType,
+                                                                         Function<RequestBody, Void> executeRequest) {
+        stubAnyPutRequest();
+        byte[] content = "test content".getBytes(StandardCharsets.UTF_8);
+        ContentStreamProvider contentProvider = () -> new ByteArrayInputStream(content);
+        RequestBody providerBody = RequestBody.fromContentProvider(contentProvider, "application/octet-stream");
+        executeRequest.apply(providerBody);
+        assertExpectHeaderPresent();
+    }
+
+    @ParameterizedTest(name = "{0}_withEmptyBody_doesNotSendExpectHeader")
+    @MethodSource("asyncRequestProvider")
+    void asyncOperation_withEmptyBody_doesNotSendExpectHeader(String operationType,
+                                                              Function<AsyncRequestBody, CompletableFuture<?>> executeRequest) {
+        stubAnyPutRequest();
+        executeRequest.apply(AsyncRequestBody.empty()).join();
+        assertExpectHeaderNotPresent();
+    }
+
+    @ParameterizedTest(name = "{0}_withEmptyStringBody_doesNotSendExpectHeader")
+    @MethodSource("asyncRequestProvider")
+    void asyncOperation_withEmptyStringBody_doesNotSendExpectHeader(String operationType,
+                                                                    Function<AsyncRequestBody, CompletableFuture<?>> executeRequest) {
+        stubAnyPutRequest();
+        executeRequest.apply(AsyncRequestBody.fromString("")).join();
+        assertExpectHeaderNotPresent();
+    }
+
+    @ParameterizedTest(name = "{0}_withNonEmptyBody_sendsExpectHeader")
+    @MethodSource("asyncRequestProvider")
+    void asyncOperation_withNonEmptyBody_sendsExpectHeader(String operationType,
+                                                           Function<AsyncRequestBody, CompletableFuture<?>> executeRequest) {
+        stubAnyPutRequest();
+        executeRequest.apply(AsyncRequestBody.fromString("test content")).join();
+        assertExpectHeaderPresent();
+    }
+
+    @ParameterizedTest(name = "{0}_withPublisherEmptyBody_sendsExpectHeader")
+    @MethodSource("asyncRequestProvider")
+    void asyncOperation_withPublisherEmptyBody_sendsExpectHeader(String operationType,
+                                                                 Function<AsyncRequestBody, CompletableFuture<?>> executeRequest) {
+        stubAnyPutRequest();
+        Publisher<ByteBuffer> emptyPublisher = subscriber -> {
+            subscriber.onSubscribe(new Subscription() {
+                @Override
+                public void request(long n) {
+                    subscriber.onComplete();
+                }
+
+                @Override
+                public void cancel() {
+                }
+            });
+        };
+
+        AsyncRequestBody emptyBody = AsyncRequestBody.fromPublisher(emptyPublisher);
+        executeRequest.apply(emptyBody).join();
+        assertExpectHeaderPresent();
+    }
+
+    @ParameterizedTest(name = "{0}_withPublisherNonEmptyBody_sendsExpectHeader")
+    @MethodSource("asyncRequestProvider")
+    void asyncOperation_withPublisherNonEmptyBody_sendsExpectHeader(String operationType,
+                                                                    Function<AsyncRequestBody, CompletableFuture<?>> executeRequest) {
+        stubAnyPutRequest();
+        byte[] content = "test content".getBytes(StandardCharsets.UTF_8);
+        Publisher<ByteBuffer> contentPublisher = subscriber -> {
+            subscriber.onSubscribe(new Subscription() {
+                private boolean sent = false;
+
+                @Override
+                public void request(long n) {
+                    if (!sent && n > 0) {
+                        sent = true;
+                        subscriber.onNext(ByteBuffer.wrap(content));
+                        subscriber.onComplete();
+                    }
+                }
+
+                @Override
+                public void cancel() {
+                }
+            });
+        };
+
+        AsyncRequestBody publisherBody = AsyncRequestBody.fromPublisher(contentPublisher);
+        executeRequest.apply(publisherBody).join();
+        assertExpectHeaderPresent();
+    }
+
+    private Stream<Arguments> syncRequestProvider() {
+        return Stream.of(
+            Arguments.of("PutObject", (Function<RequestBody, Void>) body -> {
+                syncClient.putObject(basePutObjectRequest().build(), body);
+                return null;
+            }),
+            Arguments.of("UploadPart", (Function<RequestBody, Void>) body -> {
+                syncClient.uploadPart(baseUploadPartRequest().build(), body);
+                return null;
+            })
+        );
+    }
+
+    private Stream<Arguments> asyncRequestProvider() {
+        return Stream.of(
+            Arguments.of("PutObject", (Function<AsyncRequestBody, CompletableFuture<?>>) body ->
+                asyncClient.putObject(basePutObjectRequest().build(), body)),
+            Arguments.of("UploadPart", (Function<AsyncRequestBody, CompletableFuture<?>>) body ->
+                asyncClient.uploadPart(baseUploadPartRequest().build(), body))
+        );
+    }
+
+    private PutObjectRequest.Builder basePutObjectRequest() {
+        return PutObjectRequest.builder()
+                               .bucket(BUCKET)
+                               .key(KEY);
+    }
+
+    private UploadPartRequest.Builder baseUploadPartRequest() {
+        return UploadPartRequest.builder()
+                                .bucket(BUCKET)
+                                .key(KEY)
+                                .uploadId(UPLOAD_ID)
+                                .partNumber(1);
+    }
+
+    private void stubAnyPutRequest() {
+        stubFor(put(anyUrl())
+                    .willReturn(aResponse()
+                                    .withStatus(200)
+                                    .withHeader("ETag", "\"test-etag\"")));
+    }
+
+    private void assertExpectHeaderNotPresent() {
+        LoggedRequest request = getSingleCapturedRequest();
+
+        assertThat(request.header("Expect") == null || !request.header("Expect").isPresent())
+            .as("Expect header should not be present for empty body per RFC 9110 Section 10.1.1")
+            .isTrue();
+    }
+
+    private void assertExpectHeaderPresent() {
+        LoggedRequest request = getSingleCapturedRequest();
+
+        assertThat(request.header("Expect"))
+            .as("Expect: 100-continue header should be present for non-empty body")
+            .isNotNull()
+            .satisfies(header -> assertThat(header.firstValue()).isEqualTo("100-continue"));
+    }
+
+    private LoggedRequest getSingleCapturedRequest() {
+        List<LoggedRequest> requests = findAll(putRequestedFor(anyUrl()));
+
+        assertThat(requests)
+            .as("Expected exactly one HTTP request to be captured")
+            .hasSize(1);
+
+        return requests.get(0);
+    }
+}