sshpeer: move URL validation out of sshpeer.__init__

We will soon have another SSH peer class to support the new version
of the SSH protocol. However, we won't know which peer class to
instantiate until we perform a handshake on an active connection.
This means that we need to move connection establishment and handshake
code out of sshpeer.__init__.

This commit starts the process of migrating peer creation code
out of sshpeer.__init__ into instance(), which is the API for
creating peers.

The moved code no longer calls _abort(). _abort() runs _cleanup() and
raises. _cleanup() only performs actions on self._pipe*. These objects
aren't instantiated until we actually connect to the peer. So _abort()
was not necessary in the old code.

To keep the API the same, __init__() now makes a redundant call to
util.url(). This will be fixed in subsequent commits.

Differential Revision: https://phab.mercurial-scm.org/D2027

mercurial/sshpeer.py

@@ -121,13 +121,6 b' class sshpeer(wireproto.wirepeer):'
         self._pipeo = self._pipei = self._pipee = None
 
         u = util.url(path, parsequery=False, parsefragment=False)
-        if u.scheme != 'ssh' or not u.host or u.path is None:
-            self._abort(error.RepoError(_("couldn't parse location %s") % path))
-
-        util.checksafessh(path)
-
-        if u.passwd is not None:
-            self._abort(error.RepoError(_("password in URL not supported")))
 
         self._user = u.user
         self._host = u.host
@@ -371,4 +364,17 b' class sshpeer(wireproto.wirepeer):'
         self._readerr()
 
 def instance(ui, path, create):
+    """Create an SSH peer.
+
+    The returned object conforms to the ``wireproto.wirepeer`` interface.
+    """
+    u = util.url(path, parsequery=False, parsefragment=False)
+    if u.scheme != 'ssh' or not u.host or u.path is None:
+        raise error.RepoError(_("couldn't parse location %s") % path)
+
+    util.checksafessh(path)
+
+    if u.passwd is not None:
+        raise error.RepoError(_('password in URL not supported'))
+
     return sshpeer(ui, path, create=create)