Prior to this change, we default to SSLv23, which is insecure because
it allows use of SSLv2. Unfortunately, there's no constant for OpenSSL
to let us use SSLv3 or TLS - we have to pick one or the other. We
expose a knob to revert to pre-TLS SSL for the user that has an
ancient server that lacks proper TLS support.
Python docs are a little unclear, but mpm reports reading the OpenSSL
source code shows that PROTOCOL_SSLv23 allows TLS whereas
PROTOCOL_SSLv3 does not.
We can't (easily) force SSL version on older Pythons, but on 2.6 and
later we can force SSLv3, which is safer and widely supported. This
also appears to work around a bug in IIS detailed in issue 3905.
Before this patch, "sslutil.validator" may returns successfully, even
if peer certificate is not verified because there is no information in
"[hostfingerprints]" and "[web] cacerts".
To prevent from sending authentication credential to untrustable SMTP
server, validation should be aborted if peer certificate is not
verified.
This patch introduces "strict" optional argument, and
"sslutil.validator" will abort if it is True and peer certificate is
not verified.
Some platforms, notably Plan 9 from Bell Labs are stuck on older
releases of Python. Due to restrictions in the platform, it is not
possible to backport the SSL library to the existing Python port.
This patch permits the UI to quiesce SSL verification warnings by
adding a configuration entry named reportoldssl to ui.
The previous workaround for correct handling of wrapping of failing connections
might be enough to prevent this from happening, but the check here makes this
function more robust.
This works around that ssl.wrap_socket silently skips ssl negotiation on
sockets that was connected but since then has been reset by the peer but not
yet closed at the Python level. That leaves the socket in a state where
.getpeercert() fails with an AttributeError on None. See
http://bugs.python.org/issue13721 .
A call to .cipher() is now used to verify that the wrapping really did succeed.
Otherwise it aborts with "ssl connection failed".
It is apparently possible to compile Python without SSL support or leave it out
when installing precompiled binaries.
Mercurial on such Pythons would crash if the user tried to use https. Now it
will be reported as "abort: Python SSL support not found" instead.
Any entries in subjectAltName would prevent fallback to using commonName, but
RFC 2818 says:
If a subjectAltName extension of type dNSName is present, that MUST
be used as the identity. Otherwise, the (most specific) Common Name
field in the Subject field of the certificate MUST be used.
We now only consider dNSNames in subjectAltName.
(dNSName is known as 'DNS' in OpenSSL/Python.)
Two imports were omitted in the restructure of the code creating
sslutil.py, socket and httplib are required when the 'ssl' module
cannot be imported, restoring these imports allows mercurial to run
on python2.4+2.5.
