sslutil: convert socket validation from a class to a function (API)

Now that the socket validator doesn't have any instance state,
we can make it a generic function.

The "validator" class has been converted into the "validatesocket"
function and all consumers have been updated.

mercurial/httpconnection.py

@@ -284,6 +284,6 b' class http2handler(urlreq.httphandler, u'
 
         con = HTTPConnection(host, port, use_ssl=True,
                              ssl_wrap_socket=sslutil.wrapsocket,
-                             ssl_validator=sslutil.validator(self.ui, host),
+                             ssl_validator=sslutil.validatesocket,
                              **kwargs)
         return con

mercurial/mail.py

@@ -139,7 +139,7 b' def _smtp(ui):'
         s.ehlo()
     if (starttls or smtps) and verifycert:
         ui.note(_('(verifying remote certificate)\n'))
-        sslutil.validator(ui, mailhost)(s.sock, verifycert == 'strict')
+        sslutil.validatesocket(s.sock, verifycert == 'strict')
     username = ui.config('smtp', 'username')
     password = ui.config('smtp', 'password')
     if username and not password:

mercurial/sslutil.py

@@ -291,11 +291,11 b' def sslkwargs(ui, host):'
 
     return kws
 
-class validator(object):
-    def __init__(self, ui=None, host=None):
-        pass
+def validatesocket(sock, strict=False):
+    """Validate a socket meets security requiremnets.
 
-    def __call__(self, sock, strict=False):
+    The passed socket must have been created with ``wrapsocket()``.
+    """
         host = sock._hgstate['hostname']
         ui = sock._hgstate['ui']
 

mercurial/url.py

@@ -356,7 +356,7 b' if has_https:'
             self.sock = sslutil.wrapsocket(
                 self.sock, self.key_file, self.cert_file, serverhostname=host,
                 **sslutil.sslkwargs(self.ui, host))
-            sslutil.validator(self.ui, host)(self.sock)
+            sslutil.validatesocket(self.sock)
 
     class httpshandler(keepalive.KeepAliveHandler, urlreq.httpshandler):
         def __init__(self, ui):