qtls: protect the tls.ClientSessionCache implementation with a mutex #4319
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This prevents a race condition when the underlying ClientSessionCache provided by the application returns the same session ticket for multiple connections. Reusing session tickets is explicitly recommended against by both RFC 8446 and RFC 9001, but it's not forbidden. This fix only benefits applications that compromise their users' privacy by reusing session tickets.
Codecov ReportAll modified and coverable lines are covered by tests ✅
Additional details and impacted files@@ Coverage Diff @@
## master #4319 +/- ##
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+ Coverage 84.15% 84.16% +0.01%
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Files 150 150
Lines 15368 15374 +6
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+ Hits 12932 12938 +6
+ Misses 1938 1937 -1
- Partials 498 499 +1 ☔ View full report in Codecov by Sentry. |
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As mentioned in #4318, we weren't able to reproduce the race in our code reliably yet. As far as I can see, the original code is not explicitly reusing any session tickets. It essentially is trying to establish both an HTTP/2 and an HTTP/3 connection to the same endpoint at the same time to see which protocol is faster. The code in the PR looks good to me, but I wonder if I should file an issue about the unclear documentation in the Go repo? |
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Not sure what documentation you want to improve. Warn against the reuse of session tickets? That sounds like a worthwhile change. |
…uic-go#4319) This prevents a race condition when the underlying ClientSessionCache provided by the application returns the same session ticket for multiple connections. Reusing session tickets is explicitly recommended against by both RFC 8446 and RFC 9001, but it's not forbidden. This fix only benefits applications that compromise their users' privacy by reusing session tickets.
This prevents a race condition when the underlying ClientSessionCache provided by the application returns the same session ticket for multiple connections. Reusing session tickets is explicitly recommended against by both RFC 8446 and RFC 9001, but it's not forbidden. This fix only benefits applications that compromise their users' privacy by reusing session tickets.
@ainar-g Could you give this PR a try? As a permanent fix, I'd recommend not reusing session tickets though.