clean up SSHException subclass args and string methods

Setting "self.args" is equivalent to calling the parent class
__init__() method with those args, and also overrides the only
thing that parent class __init__() method did. It is confused.

What is actually desired is to override the __str__() method with
a custom formatted exception message. The default for Exception
with zero args is blank, with one arg is the str of that arg,
with multiple args is just the repr of the args tuple.
(That never includes the class name. So, we want custom str.)

1 files changed, 28 insertions, 31 deletions

diff --git a/paramiko/ssh_exception.py b/paramiko/ssh_exception.py
index 52bb23be..fc71ae2a 100644
--- a/paramiko/ssh_exception.py
+++ b/paramiko/ssh_exception.py
@@ -56,20 +56,16 @@ class BadAuthenticationType(AuthenticationException):
     .. versionadded:: 1.1
     """
 
-    #: list of allowed authentication types provided by the server (possible
-    #: values are: ``"none"``, ``"password"``, and ``"publickey"``).
     allowed_types = []
 
     def __init__(self, explanation, types):
-        AuthenticationException.__init__(self, explanation)
+        AuthenticationException.__init__(self, explanation, types)
         self.allowed_types = types
-        # for unpickling
-        self.args = (explanation, types)
 
     def __str__(self):
-        return "{} (allowed_types={!r})".format(
-            SSHException.__str__(self), self.allowed_types
-        )
+        msg = "Bad authentication type, allowed types: "
+        msg += ",".join(self.allowed_types)
+        return msg
 
 
 class PartialAuthentication(AuthenticationException):
@@ -80,10 +76,13 @@ class PartialAuthentication(AuthenticationException):
     allowed_types = []
 
     def __init__(self, types):
-        AuthenticationException.__init__(self, "partial authentication")
+        AuthenticationException.__init__(self, types)
         self.allowed_types = types
-        # for unpickling
-        self.args = (types,)
+
+    def __str__(self):
+        msg = "Partial authentication, allowed types: "
+        msg += ",".join(self.allowed_types)
+        return msg
 
 
 class ChannelException(SSHException):
@@ -96,10 +95,11 @@ class ChannelException(SSHException):
     """
 
     def __init__(self, code, text):
-        SSHException.__init__(self, text)
+        SSHException.__init__(self, code, text)
         self.code = code
-        # for unpickling
-        self.args = (code, text)
+
+    def __str__(self):
+        return "ChannelException: %s, %s" % self.args
 
 
 class BadHostKeyException(SSHException):
@@ -114,18 +114,17 @@ class BadHostKeyException(SSHException):
     """
 
     def __init__(self, hostname, got_key, expected_key):
-        message = (
-            "Host key for server {} does not match: got {}, expected {}"
-        )  # noqa
-        message = message.format(
-            hostname, got_key.get_base64(), expected_key.get_base64()
-        )
-        SSHException.__init__(self, message)
+        SSHException.__init__(self, hostname, got_key, expected_key)
         self.hostname = hostname
         self.key = got_key
         self.expected_key = expected_key
-        # for unpickling
-        self.args = (hostname, got_key, expected_key)
+
+    def __str__(self):
+        return "Host key for server %s does not match: got %s, expected %s" % (
+            self.hostname,
+            self.got_key.get_base64(),
+            self.expected_key.get_base64(),
+        )
 
 
 class ProxyCommandFailure(SSHException):
@@ -137,15 +136,13 @@ class ProxyCommandFailure(SSHException):
     """
 
     def __init__(self, command, error):
-        SSHException.__init__(
-            self,
-            '"ProxyCommand ({})" returned non-zero exit status: {}'.format(
-                command, error
-            ),
-        )
+        SSHException.__init__(self, command, error)
         self.error = error
-        # for unpickling
-        self.args = (command, error)
+
+    def __str__(self):
+        return (
+            "ProxyCommand (%s) returned non-zero exit status: %s" % self.args
+        )
 
 
 class NoValidConnectionsError(socket.error):