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Use SSL_sendfile() from OpenSSL 3.0 in SSLSocket.sendfile when available. #99813

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Use SSL_sendfile() from OpenSSL 3.0 in SSLSocket.sendfile when available.#99813
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stdlibStandard Library Python modules in the Lib/ directorytopic-SSLtype-featureA feature request or enhancement

Description

@moonsikpark
moonsikpark
opened on Nov 27, 2022

Feature or enhancement

SSL_sendfile() is a function added in OpenSSL 3.0. If we use this function, we can offload TLS to the kernel, which can hugely improve performance. However, both the kernel and OpenSSL must be built with kTLS support.

I would like to prepare a PR that enables SSL_sendfile() use in SSLSocket.sendfile.

Pitch

This would enable use of kernel TLS, which will yield significant increase of TLS performance in systems with kTLS support.

Previous discussion

https://discuss.python.org/t/sslsocket-sendfile-and-kernel-tls/18886

Linked PRs

Activity

  1. moonsikpark
    added
    type-featureA feature request or enhancement
    on Nov 27, 2022
  2. moonsikpark
    changed the title [-]Use `SSL_sendfile()` from OpenSSL 3.0 when avalible.[/-] [+]Use `SSL_sendfile()` from OpenSSL 3.0 in `SSLSocket.sendfile` when available.[/+] on Nov 27, 2022
  3. hugovk
    added
    topic-SSL
    stdlibStandard Library Python modules in the Lib/ directory
    on Nov 27, 2022

  4. illia-v commented on Nov 29, 2022

    @illia-v
    illia-v
    on Nov 29, 2022
    Contributor

    @moonsikpark thanks for opening the issue. I want to let you know that I made some progress in integrating the function in September and a little bit after #96830 was merged. It will be inefficient if we spend time solving the same problem. Let me open a PR with what I have tomorrow, then we can cooperate on finalizing this.

  5. moonsikpark commented on Nov 30, 2022

    @moonsikpark
    moonsikpark
    on Nov 30, 2022
    ContributorAuthor

    @illia-v I've finished basic PoC of using SSL_sendfile() in this branch. If your progress is beyond what I've been working on, It'd be nice if you open the PR with yours :)

  6. illia-v commented on Nov 30, 2022

    @illia-v
    illia-v
    on Nov 30, 2022
    Contributor

    @illia-v I've finished basic PoC of using SSL_sendfile() in this branch. If your progress is beyond what I've been working on, It'd be nice if you open the PR with yours :)

    Cool! I created #99907, please leave your feedback about it.

    Comparing to your branch, my version:

    • incorporates some sendfile usage experience moved to socket.socket._sendfile_zerocopy;
    • falls back to _sendfile_use_send;
    • follows _ssl__SSLSocket_write_impl error handling;
    • does not define _ssl._SSLSocket.sendfile at all if it unavailable similarly to how os.sendfile is not always defined.
  7. picnixz
    added a commit that references this issue on Jul 12, 2025

    gh-99813: Start using `SSL_sendfile` when available (#99907)

    5a20e79
  8. Pranjal095
    added a commit that references this issue on Jul 12, 2025

    pythongh-99813: Start using `SSL_sendfile` when available (python#99907)

    34467b4
  9. picnixz
    added a commit that references this issue on Jul 13, 2025

    pythongh-99813: Start using `SSL_sendfile` when available (python#99907)

    613e3b9
  10. taegyunkim
    added a commit that references this issue on Aug 4, 2025

    pythongh-99813: Start using `SSL_sendfile` when available (python#99907)

    d2d1edd
  11. Agent-Hellboy
    added a commit that references this issue on Aug 19, 2025

    pythongh-99813: Start using `SSL_sendfile` when available (python#99907)

    e46a963

  12. StanFromIreland commented on Oct 13, 2025

    @StanFromIreland
    StanFromIreland
    on Oct 13, 2025
    Member

    @picnixz can this be closed as completed?

  13. StanFromIreland
    added
    pendingThe issue will be closed if no feedback is provided
    on Oct 13, 2025
  14. picnixz
    removed
    pendingThe issue will be closed if no feedback is provided
    on Oct 13, 2025

  15. picnixz commented on Oct 13, 2025

    @picnixz
    picnixz
    on Oct 13, 2025
    Member

    Yes

  16. picnixz
    closed this as completedon Oct 13, 2025
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