On Fri, 27 Feb 2026 16:03:00 GMT, Daniel Fuchs <[email protected]> wrote:

>> PeerConnectionId has a constructor that takes a ByteBuffer containing the 
>> peer connection id bytes. This constructor extracts the connection id bytes 
>> from the given byte buffer and makes a private copy for itself. However, 
>> while doing so, it uses a relative bulk get instead of an absolute bulk get, 
>> which causes the original byte buffer position to move to the limit.
>> 
>> This is causing trouble on the server side, this is the only place where 
>> that constructor is used without making a slice of the original buffer 
>> first. In some circumstances (if the connection id is not found) it can 
>> cause the first initial packet to get dropped after creating the connection. 
>> This went unnoticed because the client will then retransmit that packet, and 
>> the connection id will be found the next time around.
>> 
>> Though the issue is in product source code it only affects the server side 
>> used by httpclient tests. 
>> 
>> The proposed change first adds some assert statements to 
>> `QuicConnectionImpl::internalProcessIncoming` and ensure that the connection 
>> will get closed if the assert fires. This made it possible to reproduce and 
>> surface the issue quite easily using existing httpclient tests: a lot of 
>> tests started failing with that change ([this is done by the first commit in 
>> this 
>> PR](https://github.com/openjdk/jdk/pull/29956/changes/b81ce5d405054b06afdf70738119916bba08ce72)).
>> The [second 
>> commit](https://github.com/openjdk/jdk/pull/29956/changes/108660362d4fa78e61c784931fe6d45e002381dc)
>>  fixes the issue by making `PeerConnectionId::cloneBuffer` use an absolute 
>> bulk get instead of a relative bulk get. The absolute bulk get ensures that 
>> the position of the input buffer is not moved while copying it.
>> 
>> I am marking the issue as `noreg-hard` - though it could be very easily 
>> verified by undoing the second commit, recompiling the JDK, and running the 
>> test with that. Then add the second commit, recompile, and see that all 
>> tests are passing.
>
> Daniel Fuchs has updated the pull request incrementally with one additional 
> commit since the last revision:
> 
>   Review feedback: add comment

Marked as reviewed by vyazici (Reviewer).

-------------

PR Review: https://git.openjdk.org/jdk/pull/29956#pullrequestreview-3867751498

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