view tests/svnxml.py @ 33492:14af04391fb9

win32: add a method to trigger the Crypto API to complete a certificate chain

I started a thread[1] on the mailing list awhile ago, but the short version is
that Windows doesn't ship with a full list of certificates[2].  Even if the
server sends the whole chain, if Windows doesn't have the appropriate
certificate pre-installed in its "Third-Party Root Certification Authorities"
store, connections mysteriously fail with:

  abort: error: [SSL: CERTIFICATE_VERIFY_FAILED] certificate verify failed (_ssl.c:661)

Windows expects the application to call the methods invoked here as part of the
certificate verification, triggering a call out to Windows update if necessary,
to complete the trust chain.  The python bug to add this support[3] hasn't had
any recent activity, and isn't targeting py27 anyway.

The only work around that I could find (besides figuring out the certificate and
walking through the import wizard) is to browse to the site in Internet
Explorer.  Opening the page with FireFox or Chrome didn't work.  That's a pretty
obscure way to fix a pretty obscure problem.  We go to great lengths to
demystify various SSL errors, but this case is clearly lacking.  Let's try to
make things easier to diagnose and fix.

When I had trouble figuring out how to get ctypes to work with all of the API
pointers, I found that there are other python projects[4] using this API to
achieve the same thing.

[1] https://www.mercurial-scm.org/pipermail/mercurial-devel/2017-April/096501.html
[2] https://support.microsoft.com/en-us/help/931125/how-to-get-a-root-certificate-update-for-windows
[3] https://bugs.python.org/issue20916
[4] https://github.com/nvaccess/nvda/blob/3b86bce2066b1934df14b96f2e83369900860ecf/source/updateCheck.py#L511

# Read the output of a "svn log --xml" command on stdin, parse it and
# print a subset of attributes common to all svn versions tested by
# hg.
from __future__ import absolute_import
import sys
import xml.dom.minidom

def xmltext(e):
    return ''.join(c.data for c
                   in e.childNodes
                   if c.nodeType == c.TEXT_NODE)

def parseentry(entry):
    e = {}
    e['revision'] = entry.getAttribute('revision')
    e['author'] = xmltext(entry.getElementsByTagName('author')[0])
    e['msg'] = xmltext(entry.getElementsByTagName('msg')[0])
    e['paths'] = []
    paths = entry.getElementsByTagName('paths')
    if paths:
        paths = paths[0]
        for p in paths.getElementsByTagName('path'):
            action = p.getAttribute('action')
            path = xmltext(p)
            frompath = p.getAttribute('copyfrom-path')
            fromrev = p.getAttribute('copyfrom-rev')
            e['paths'].append((path, action, frompath, fromrev))
    return e

def parselog(data):
    entries = []
    doc = xml.dom.minidom.parseString(data)
    for e in doc.getElementsByTagName('logentry'):
        entries.append(parseentry(e))
    return entries

def printentries(entries):
    fp = sys.stdout
    for e in entries:
        for k in ('revision', 'author', 'msg'):
            fp.write(('%s: %s\n' % (k, e[k])).encode('utf-8'))
        for path, action, fpath, frev in sorted(e['paths']):
            frominfo = ''
            if frev:
                frominfo = ' (from %s@%s)' % (fpath, frev)
            p = ' %s %s%s\n' % (action, path, frominfo)
            fp.write(p.encode('utf-8'))

if __name__ == '__main__':
    data = sys.stdin.read()
    entries = parselog(data)
    printentries(entries)