8358942: HttpClient adds Content-Length: 0 for a GET request with a BodyPublishers.noBody() #27727

djelinski · 2025-10-09T13:27:42Z

Do not send the Content-Length header on HTTP/1.1 requests when the content length is known to be zero and the method does not expect content or is unknown.

This brings the HTTP/1.1 implementation in line with the recommendations from RFC 9110.

The existing ContentLengthHeaderTest was extended to cover the modified scenarios.

Tier1-3 tests continue to pass.

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Change must be properly reviewed (1 review required, with at least 1 Reviewer)
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Change requires CSR request JDK-8369533 to be approved
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Issues

JDK-8358942: HttpClient adds Content-Length: 0 for a GET request with a BodyPublishers.noBody() (Bug - P4)
JDK-8369533: HttpClient adds Content-Length: 0 for a GET request with a BodyPublishers.noBody() (CSR)

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Daniel Fuchs (@dfuch - Reviewer)
Volkan Yazici (@vy - Committer)

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Update a local copy of the PR:
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$ git pull https://git.openjdk.org/jdk.git pull/27727/head

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bridgekeeper · 2025-10-09T13:30:01Z

👋 Welcome back djelinski! A progress list of the required criteria for merging this PR into master will be added to the body of your pull request. There are additional pull request commands available for use with this pull request.

openjdk · 2025-10-09T13:32:48Z

@djelinski This change now passes all automated pre-integration checks.

ℹ️ This project also has non-automated pre-integration requirements. Please see the file CONTRIBUTING.md for details.

After integration, the commit message for the final commit will be:

8358942: HttpClient adds Content-Length: 0 for a GET request with a BodyPublishers.noBody()

Reviewed-by: dfuchs, vyazici

You can use pull request commands such as /summary, /contributor and /issue to adjust it as needed.

At the time when this comment was updated there had been 118 new commits pushed to the master branch:

a7a3a66: 8354469: Keytool exposes the password in plain text when command is piped using | grep
c9cbd31: 8307495: Specialize atomic bitset functions for aix-ppc
bfe6937: 8369444: JavaFrameAnchor on PPC64 has unnecessary barriers
... and 115 more: https://git.openjdk.org/jdk/compare/d27649fe22a5bed9db72ac6c2595ac91f1fa28f8...master

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openjdk · 2025-10-09T13:34:25Z

@djelinski The following label will be automatically applied to this pull request:

net

When this pull request is ready to be reviewed, an "RFR" email will be sent to the corresponding mailing list. If you would like to change these labels, use the /label pull request command.

mlbridge · 2025-10-10T10:22:00Z

Webrevs

test/jdk/java/net/httpclient/ContentLengthHeaderTest.java

vy · 2025-10-13T07:31:40Z

test/jdk/java/net/httpclient/ContentLengthHeaderTest.java

+        HttpResponse<String> resp = hc.send(req, HttpResponse.BodyHandlers.ofString(UTF_8));
+        assertEquals(resp.statusCode(), 200, resp.body());
+        assertEquals(resp.version(), version);
+        assertEquals(resp.body(), "Request completed");


If possible, you may consider verifying the response body in other test methods too, since, in particular, OptionalContentLengthHandler responds with 200 in two different scenarios.

That's not possible in most cases: in HTTP/2 and HTTP/3 we don't send the content-length:0 header, we only send content-length when it's known up front and non-zero.
In cases where it is possible it's usually not necessary - most of the time we don't really care if the content length was sent or not, as long as the server is able to figure it out.

I'll add a check for the HTTP/1 + PUT/POST case, since that's special-cased by this PR.

If I'm not mistaken in case of H2/H3 you could verify that:

assertTrue(List.of("Request completed, no content length", "Request completed").contains(resp.body()), "Unexpected response: " + resp.body());

I ended up removing the OptionalContentLengthHandler. It didn't feel right anyway.

OptionalContentLengthHandler gone feels better. This also implies that the check is stricter: we either expect the Content-Length, or not.

vy · 2025-10-13T10:08:35Z

Why is this an HTTP/1.1-only problem?

HTTP/2 and HTTP/3 implementations of HttpClient already add the Content-Length header iff it is greater than zero:

jdk/src/java.net.http/share/classes/jdk/internal/net/http/Stream.java

Lines 906 to 908 in 4728f74

    
           if (contentLength > 0) { 
        
               h.setHeader("content-length", Long.toString(contentLength)); 
        
           }

jdk/src/java.net.http/share/classes/jdk/internal/net/http/Http3ExchangeImpl.java

Lines 388 to 390 in 4728f74

    
           if (requestContentLen > 0) { 
        
               h.setHeader("content-length", Long.toString(requestContentLen)); 
        
           }

They do this, unlike the POST and PUT exemption for HTTP/1.1 in the proposed PR, for all methods.
This behavior difference between HTTP/1 and HTTP/{2,3} is not a problem because

HTTP/2 and HTTP/3 are implicitly chunked when Content-Length is missing.
Content-Length is always optional for HTTP/2 and HTTP/3, for all methods. A user agent may add it, in which case it must match the total number of bytes sent in the body request.

Credits: Thanks to @dfuch and @djelinski for patiently answering my questions.

test/jdk/java/net/httpclient/ContentLengthHeaderTest.java

vy · 2025-10-15T08:13:20Z

test/jdk/java/net/httpclient/ContentLengthHeaderTest.java

+        HttpResponse<String> resp = hc.send(req, HttpResponse.BodyHandlers.ofString(UTF_8));
+        assertEquals(resp.statusCode(), 200, resp.body());
+        assertEquals(resp.version(), version);
+        assertEquals(resp.body(), "Request completed");


OptionalContentLengthHandler gone feels better. This also implies that the check is stricter: we either expect the Content-Length, or not.

dfuch · 2025-10-15T10:07:42Z

@djelinski you should probably Finalize the CSR JDK-8369533 now.

djelinski · 2025-10-16T11:04:41Z

Thanks for the reviews!

/integrate

openjdk · 2025-10-16T11:05:18Z

Going to push as commit ead35a7.
Since your change was applied there have been 129 commits pushed to the master branch:

d6c122b: 8369982: ProblemList jdk/jfr/jvm/TestWaste.java
6e911d8: 8368205: [TESTBUG] VectorMaskCompareNotTest.java crashes when MaxVectorSize=8
b5b8324: 8369656: Calling CompletableFuture.join() could execute task in common pool
... and 126 more: https://git.openjdk.org/jdk/compare/d27649fe22a5bed9db72ac6c2595ac91f1fa28f8...master

Your commit was automatically rebased without conflicts.

openjdk · 2025-10-16T11:05:27Z

@djelinski Pushed as commit ead35a7.

💡 You may see a message that your pull request was closed with unmerged commits. This can be safely ignored.

Do not send content-length if body is empty and the method doesn't ex…

11892a7

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openjdk bot changed the title ~~8358942~~ 8358942: HttpClient adds Content-Length: 0 for a GET request with a BodyPublishers.noBody() Oct 9, 2025

openjdk bot added the net [email protected] label Oct 9, 2025

openjdk bot added the csr Pull request needs approved CSR before integration label Oct 10, 2025

djelinski marked this pull request as ready for review October 10, 2025 10:18

openjdk bot added the rfr Pull request is ready for review label Oct 10, 2025

dfuch reviewed Oct 10, 2025

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test/jdk/java/net/httpclient/ContentLengthHeaderTest.java Show resolved Hide resolved

Add test explicitly setting content length to zero

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vy reviewed Oct 13, 2025

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dfuch approved these changes Oct 13, 2025

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djelinski added 2 commits October 14, 2025 17:05

Check that content-length is sent on POST/PUT with empty body

da849bf

More strict verification of content-length handling

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dfuch reviewed Oct 14, 2025

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test/jdk/java/net/httpclient/ContentLengthHeaderTest.java Outdated Show resolved Hide resolved

Remove leftover check

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vy approved these changes Oct 15, 2025

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dfuch approved these changes Oct 15, 2025

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openjdk bot added ready Pull request is ready to be integrated and removed csr Pull request needs approved CSR before integration labels Oct 15, 2025

openjdk bot added the integrated Pull request has been integrated label Oct 16, 2025

openjdk bot closed this Oct 16, 2025

openjdk bot removed ready Pull request is ready to be integrated rfr Pull request is ready for review labels Oct 16, 2025

8358942: HttpClient adds Content-Length: 0 for a GET request with a BodyPublishers.noBody() #27727

8358942: HttpClient adds Content-Length: 0 for a GET request with a BodyPublishers.noBody() #27727

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Why is this an HTTP/1.1-only problem?

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