[tor-bugs] #25353 [Core Tor/Tor]: Configure fails with some OpenSSL 1.1.0

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#25353: Configure fails with some OpenSSL 1.1.0
-------------------------+-------------------------------------------------
     Reporter:           |      Owner:  (none)
  laomaiweng             |
         Type:  defect   |     Status:  new
     Priority:  Medium   |  Milestone:  Tor: unspecified
    Component:  Core     |    Version:
  Tor/Tor                |   Keywords:  openssl, 1.1.0, tlsv1_1_method,
     Severity:  Minor    |  deprecated
Actual Points:           |  Parent ID:
       Points:           |   Reviewer:
      Sponsor:           |
-------------------------+-------------------------------------------------
 On my machine with OpenSSL 1.1.0, Tor's `configure` script fails to detect
 OpenSSL and gives me the following error:

 {{{
 configure: Now, we'll look for OpenSSL >= 1.0.1
 checking for openssl directory... configure: WARNING: Could not find a
 linkable openssl.  If you have it installed somewhere unusual, you can
 specify an explicit path using --with-openssl-dir
 configure: error: Missing libraries; unable to proceed.
 }}}

 This seems to be due to the fact that `configure` checks for OpenSSL >=
 1.0.1 with `TLSv1_1_method()`, which is deprecated in favor of
 `TLS_method()` in OpenSSL 1.1.0.
 On my configuration of OpenSSL 1.1.0, deprecated functions are not
 available by default (not without first enabling the `OPENSSL_API_COMPAT`
 compatibility #define), hence the failure.

 I'd gladly provide a patch, but I'm not sure how this would best be fixed:
 explicitly check for `TLS_method()` in case the check for
 `TLSv1_1_method()` fails? Replace this test with a test on
 `OPENSSL_VERSION_NUMBER`? Find some other function introduced in 1.0.1 and
 neither removed nor deprecated in 1.1.0?

--
Ticket URL: <https://trac.torproject.org/projects/tor/ticket/25353>
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