decorators.py

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+"""Offers decorators to make the use of django_xmlrpc a great deal simpler
+
+Authors::
+    Graham Binns,
+    Reza Mohammadi
+
+Credit must go to Brendan W. McAdams <brendan.mcadams@thewintergrp.com>, who
+posted the original SimpleXMLRPCDispatcher to the Django wiki:
+http://code.djangoproject.com/wiki/XML-RPC
+
+New BSD License
+===============
+Copyright (c) 2007, Graham Binns http://launchpad.net/~codedragon
+
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are met:
+
+    * Redistributions of source code must retain the above copyright notice,
+      this list of conditions and the following disclaimer.
+    * Redistributions in binary form must reproduce the above copyright notice,
+      this list of conditions and the following disclaimer in the documentation
+      and/or other materials provided with the distribution.
+    * Neither the name of the <ORGANIZATION> nor the names of its contributors
+      may be used to endorse or promote products derived from this software
+      without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
+LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
+A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR
+CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
+EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
+PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
+PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
+LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
+NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
+SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+"""
+from xmlrpclib import Fault
+from django.contrib.auth import authenticate
+from django.utils.translation import gettext as _
+
+
+# Some constants for your pleasure
+#XXX: Any standardization?
+AUTHENTICATION_FAILED_CODE = 81
+PERMISSION_DENIED_CODE = 82
+
+
+class AuthenticationFailedException(Fault):
+    """An XML-RPC fault to be raised when a permission_required authentication
+    check fails
+
+    Author
+    """
+    def __init__(self):
+        Fault.__init__(self, AUTHENTICATION_FAILED_CODE,
+            _('Username and/or password is incorrect'))
+
+
+class PermissionDeniedException(Fault):
+    """An XML-RPC fault to be raised when a permission_required permission
+    check fails
+    """
+    def __init__(self):
+        Fault.__init__(self, PERMISSION_DENIED_CODE, _('Permission denied'))
+
+
+def xmlrpc_method(returns='string', args=None, name=None):
+    """Adds a signature to an XML-RPC function and register
+    it with the dispatcher.
+
+    returns
+        The return type of the function. This can either be a string
+        description (e.g. 'string') or a type (e.g. str, bool) etc.
+
+    args
+        A list of the types of the arguments that the function accepts. These
+        can be strings or types or a mixture of the two e.g.
+        [str, bool, 'string']
+    """
+    # Args should be a list
+    if args is None:
+        args = []
+
+    def _xmlrpc_func(func):
+        """Inner function for XML-RPC method decoration. Adds a signature to
+        the method passed to it.
+
+        func
+            The function to add the signature to
+        """
+        # If name is not None, register the method with the dispatcher.
+        from django_xmlrpc.views import xmlrpcdispatcher
+        if name is not None:
+            xmlrpcdispatcher.register_function(func, name)
+
+        # Add a signature to the function
+        func._xmlrpc_signature = {
+            'returns': returns,
+            'args': args
+            }
+        return func
+
+    return _xmlrpc_func
+
+xmlrpc_func = xmlrpc_method
+
+
+# Don't use this decorator when your service is going to be
+# available in an unencrpted/untrusted network.
+# Configure HTTPS transport for your web server.
+def permission_required(perm=None):
+    """Decorator for authentication. Uses Django's built in authentication
+    framework to provide authenticated-only and permission-related access
+    to XML-RPC methods
+
+    perm
+        The permission (as a string) that the user must hold to be able to
+        call the function that is decorated with permission_required.
+    """
+    def _dec(func):
+        """An inner decorator. Adds the lookup code for the permission passed
+        in the outer method to the function passed to it.
+
+        func
+            The function to add the permission check to
+        """
+        def __authenticated_call(username, password, *args):
+            """Inner inner decorator. Adds username and password parameters to
+            a given XML-RPC function for authentication and permission
+            checking purposes and modifies the method signature appropriately
+
+            username
+                The username used for authentication
+
+            password
+                The password used for authentication
+            """
+            try:
+                user = authenticate(username=username, password=password)
+                if not user:
+                    raise AuthenticationFailedException
+                if perm and not user.has_perm(perm):
+                    raise PermissionDeniedException
+            except AuthenticationFailedException:
+                raise
+            except PermissionDeniedException:
+                raise
+            except:
+                raise AuthenticationFailedException
+            return func(user, *args)
+
+        # Update the function's XML-RPC signature, if the method has one
+        if hasattr(func, '_xmlrpc_signature'):
+            sig = func._xmlrpc_signature
+
+            # We just stick two string args on the front of sign['args'] to
+            # represent username and password
+            sig['args'] = (['string'] * 2) + sig['args']
+            __authenticated_call._xmlrpc_signature = sig
+
+        # Update the function's docstring
+        if func.__doc__:
+            __authenticated_call.__doc__ = func.__doc__ + \
+                "\nNote: Authentication is required."""
+            if perm:
+                __authenticated_call.__doc__ += ' this function requires ' \
+                                             + '"%s" permission.' % perm
+
+        return __authenticated_call
+
+    return _dec