Skip 'Expect: 100-continue' header for zero-length S3 streaming requests #6465
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zoewangg
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| return context.requestBody() | ||
| .flatMap(RequestBody::optionalContentLength) | ||
| .map(length -> length != 0L) | ||
| .orElse(true); |
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What about async request body? The length could also be sourced from the request itself, i.e, putObjectRequest.contentLength(). Should we check header instead? It could be content-length or x-amz-decoded-content-length
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+1, we should probably give priority to x-amz-decoded-content-length and just fall back to content-length. If the decoded length is present and 0, then it's just the trailer and I don't think we need to use expect: 100-continue for that.
L-Applin
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Oct 8, 2025
...n/java/software/amazon/awssdk/services/s3/internal/handlers/StreamingRequestInterceptor.java
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dagnir
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Motivation and Context
Fix for #6459
Per RFC 9110 Section 10.1.1, clients MUST NOT generate a 100-continue expectation in requests that do not include content. Currently, the SDK adds the
Expect: 100-continueheader to all S3 PutObject and UploadPart requests, including those with zero-length content.This causes issues with sync HTTP clients (e.g., Apache HttpClient) that reuse connections. When a zero-length request is sent with the Expect header, the server may close the connection after receiving the empty content, but the client attempts to reuse it, leading to connection errors.
RFC 9110 Reference:
Modifications
Updated
StreamingRequestInterceptorto skip adding theExpect: 100-continueheader when:Key Changes:
shouldAddExpectContinueHeader()method to check for zero-length contentBehavior:
Optional.empty()0L> 0LTesting
Added test coverage in
StreamingRequestInterceptorTest:Screenshots (if appropriate)
N/A - Code-only change
Types of changes
License
Notes
Apache 5.x
https://github.com/arturobernalg/httpcomponents-client/blob/237b5f85f743c94d9be2d26d396130bc2053f2ef/httpclient5/src/main/java/org/apache/hc/client5/http/protocol/RequestExpectContinue.java#L85-L88
Apache 4.5.x
https://github.com/apache/httpcomponents-client/blob/54900db4653d7f207477e6ee40135b88e9bcf832/httpclient/src/main/java/org/apache/http/client/protocol/RequestExpectContinue.java#L73-L75