[tor-bugs] #12646 [Ooni]: Make `requirements.txt` version constraints identical to hash constraints.

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#12646: Make `requirements.txt` version constraints identical to hash constraints.
-----------------------------+-------------------------
 Reporter:  nathan-at-least  |          Owner:  hellais
     Type:  enhancement      |         Status:  new
 Priority:  normal           |      Milestone:
Component:  Ooni             |        Version:
 Keywords:                   |  Actual Points:
Parent ID:                   |         Points:
-----------------------------+-------------------------
 Currently the `requirements.txt` for Ooni has lines like this:

 {{{
 Twisted>=12.2.0
 #https://pypi.python.org/packages/source/T/Twisted/Twisted-13.0.0.tar.bz2#md5=68afff4e1efd3757d934e39f70c99f57#egg=Twisted
 }}}

 If the first quoted line is fulfilled, many different versions may be
 installed, including `14.0`.  If the second quoted line is fulfilled then
 only a very specific (as per `md5`) dependency is used.

 If users neglect to tell the error prone and confusing python packaging
 ecosystem tools to respect the second line, and those tools only rely on
 the first version constraint, the result has two problems:

 * The process is likely to be vulnerable to an interception attack where
 the attacker replaces the to-be-installed dependency with code of their
 choice, and
 * The process, even when not attacked, will install an unsupported
 dependency version.

 A simple way to fix the second item **without addressing the security
 vulnerability** is to ensure the version constraints match the secure
 specifications.  So the above snippet would be rewritten as:

 {{{
 twisted==13.0.0
 #https://pypi.python.org/packages/source/T/Twisted/Twisted-13.0.0.tar.bz2#md5=68afff4e1efd3757d934e39f70c99f57#egg=Twisted
 }}}

 Then in a nice happy world where there are not meanies injecting malicious
 code into the install process, the vulnerable users will not encounter
 functional bugs based on version skew.

 Maybe it's a bad idea to cater to a vulnerable install, but something
 about the inconsistency here rubs me the wrong way.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/12646>
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