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7c5837e792
Disable the CURLOPT_DNS_USE_GLOBAL_CACHE option and mark it for deprecation and complete removal in six months. Bug: https://curl.haxx.se/mail/lib-2018-09/0010.html Closes #2942
94 lines
3.7 KiB
Markdown
94 lines
3.7 KiB
Markdown
# Items to be removed from future curl releases
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If any of these deprecated features is a cause for concern for you, please
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email the curl-library mailing list as soon as possible and explain to us why
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this is a problem for you and how your use case can't be satisfied properly
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using a work around.
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## axTLS backend
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Here are some complaints on axTLS.
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- home page without HTTPS
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- [doesn't support modern TLS features like SNI](https://github.com/dsheets/axtls/issues/2)
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- [lacks support for modern ciphers](https://github.com/micropython/micropython/issues/3198)
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- [doesn't allow for outside bug report submissions](https://sourceforge.net/p/axtls/bugs/)
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- there's virtually no discussion about it in its [forum](https://sourceforge.net/p/axtls/discussion/)
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nor [mailing list](https://sourceforge.net/p/axtls/mailman/axtls-general/)
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Combined, this list hints that this is not a library and project we should
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recommend to users.
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### State
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Since June 1st, 2018 (curl 7.61.0) axTLS support is disabled in code and
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requires a small code change to build without errors. [See
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PR](https://github.com/curl/curl/pull/2628)
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### Removal
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Remove all axTLS related code from curl on December 1st, exactly six months
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after previously mentioned commit. To be shipped on December 26, 2018
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(possibly called version 7.64.0)
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## HTTP pipelining
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HTTP pipelining is badly supported by curl in the sense that we have bugs and
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it is a fragile feature without enough tests. Also, when something turns out
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to have problems it is really tricky to debug due to the timing sensitivity so
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very often enabling debug outputs or similar completely changes the nature of
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the behavior and things are not reproducing anymore!
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HTTP pipelining was never enabled by default by the large desktop browsers due
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to all the issues with it. Both Firefox and Chrome have also dropped
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pipelining support entirely since a long time back now. We are in fact over
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time becoming more and more lonely in supporting pipelining.
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The bad state of HTTP pipelining was a primary driving factor behind HTTP/2
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and its multiplexing feature. HTTP/2 multiplexing is truly and really
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"pipelining done right". It is way more solid, practical and solves the use
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case in a better way with better performance and fewer downsides and problems.
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In 2018, pipelining *should* be abandoned and HTTP/2 should be used instead.
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### State
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In 7.62.0, we will add code that ignores the "enable pipeline" option
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setting). The *setopt() function would still return "OK" though so the
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application couldn't tell that this is happening.
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Users who truly need pipelining from that version will need to modify the code
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(ever so slightly) and rebuild.
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### Removal
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Six months later, in sync with the planned release happen in April 2019,
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(might be 7.66.0), assuming no major riots have occurred due to this in the
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mean time, we rip out the pipelining code. It is in the order of 1000 lines of
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libcurl code.
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Left to answer: should the *setopt() function start to return error when these
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options are set to be able to tell when they're trying to use options that are
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no longer around or should we maintain behavior as much as possible?
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## CURLOPT_DNS_USE_GLOBAL_CACHE
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This option makes libcurl use a global non-thread-safe cache for DNS if
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enabled. The option has been marked as "obsolete" in the header file and in
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documentation for several years already.
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There's proper and safe method alternative provided since many years: the
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share API.
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### State
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In curl 7.62.0 setting this option to TRUE will not have any effect. The
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global cache will not be enabled. The code still remains so it is easy to
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revert if need be.
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### Removal
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Remove all global-cache related code from curl around April 2019 (might be
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7.66.0).
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