RFR: 8359709: java.net.HttpURLConnection sends unexpected "Host" request header in some cases after JDK-8344190 [v3]

[Michael McMahon]

On Wed, 18 Jun 2025 01:51:36 GMT, Jaikiran Pai <jpai at openjdk.org> wrote:

>> Can I please get a review for this change which addresses a regression that was introduced in `HttpURLConnection` in Java 24 when we cleaned up the code by removing the references to SecurityManager APIs.
>> 
>> When a HTTP request is issued through `java.net.HttpURLConnection`, then the request URL is used to determine the `Host` header to set in the request. By default, the application cannot set a `Host` header to a different value. However the JDK allows a system property to be enabled to allow applications to explicitly set a `Host` request header when issuing the request.
>> 
>> Due to an oversight in the change that was done in https://bugs.openjdk.org/browse/JDK-8344190, the `Host` header that is set by the application, may not get used for that request causing this regression. Turns out we don't have tests in this area to catch this issue.
>> 
>> The commit in this PR fixes the regression and also introduces a new jtreg test which reproduces the issue and verifies the fix.
>> 
>> I've also checked the original change which introduced this regression https://github.com/openjdk/jdk/pull/22232 to see if there's anything else that needs attention. I haven't stopped anything else.
>
> Jaikiran Pai has updated the pull request incrementally with one additional commit since the last revision:
> 
>   Daniel's suggestion - use trailing slash for path registered for the handler

Marked as reviewed by michaelm (Reviewer).

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PR Review: https://git.openjdk.org/jdk/pull/25844#pullrequestreview-2938327484