Adds oauth checking to acceptance tests

lms/djangoapps/courseware/mock_lti_server/mock_lti_server.py

 from BaseHTTPServer import HTTPServer, BaseHTTPRequestHandler
-import json
-import urllib
 import urlparse
-import threading
-
+from requests.packages.oauthlib.oauth1.rfc5849 import signature
+import mock
 from logging import getLogger
 logger = getLogger(__name__)
 
 
-# todo - implement oauth
-
 class MockLTIRequestHandler(BaseHTTPRequestHandler):
     '''
     A handler for LTI POST requests.
@@ -28,34 +24,41 @@ class MockLTIRequestHandler(BaseHTTPRequestHandler):
 
         post_dict = self._post_dict()  # Retrieve the POST data
 
-        # Log the request
         logger.debug("LTI provider received POST request {} to path {}".format(
             str(post_dict),
             self.path)
-        )
+        )  # Log the request
+
         # Respond only to requests with correct lti endpoint:
         if self._is_correct_lti_request():
-            correct_dict = {
-                'user_id': 'default_user_id',
-                'oauth_nonce': '22990037033121997701377766132',
-                'oauth_timestamp': '1377766132',
-                'oauth_consumer_key': 'client_key',
-                'lti_version': 'LTI-1p0',
-                'oauth_signature_method': 'HMAC-SHA1',
-                'oauth_version': '1.0',
-                'oauth_signature': 'HGYMAU/G5EMxd0CDOvWubsqxLIY=',
-                'lti_message_type': 'basic-lti-launch-request',
-                'oauth_callback': 'about:blank'
-            }
-
-            if sorted(correct_dict.keys()) != sorted(post_dict.keys()):
-                error_message = "Incorrect LTI header"
+            correct_keys = [
+                'user_id',
+                'oauth_nonce',
+                'oauth_timestamp',
+                'oauth_consumer_key',
+                'lti_version',
+                'oauth_signature_method',
+                'oauth_version',
+                'oauth_signature',
+                'lti_message_type',
+                'oauth_callback',
+                'lis_outcome_service_url',
+                'lis_result_sourcedid',
+                'launch_presentation_return_url'
+            ]
+
+            if sorted(correct_keys) != sorted(post_dict.keys()):
+                status_message = "Incorrect LTI header"
             else:
-                error_message = "This is LTI tool."
+                params = {k: v for k, v in post_dict.items() if k != 'oauth_signature'}
+                if self.server.check_oauth_signature(params, post_dict['oauth_signature']):
+                    status_message = "This is LTI tool."
+                else:
+                    status_message = "Wrong LTI signature"
         else:
-            error_message = "Invalid request URL"
+            status_message = "Invalid request URL"
 
-        self._send_response(error_message)
+        self._send_response(status_message)
 
     def _send_head(self):
         '''
@@ -75,7 +78,7 @@ class MockLTIRequestHandler(BaseHTTPRequestHandler):
         '''
         try:
             length = int(self.headers.getheader('content-length'))
-            post_dict = urlparse.parse_qs(self.rfile.read(length))
+            post_dict = urlparse.parse_qs(self.rfile.read(length), keep_blank_values=True)
             # The POST dict will contain a list of values for each key.
             # None of our parameters are lists, however, so we map [val] --> val.
             #I f the list contains multiple entries, we pick the first one
@@ -110,8 +113,8 @@ class MockLTIRequestHandler(BaseHTTPRequestHandler):
         self.wfile.write(response_str)
 
     def _is_correct_lti_request(self):
-        '''If url to get LTI is correct.'''
-        return 'correct_lti_endpoint' in self.path
+        '''If url to LTI tool is correct.'''
+        return self.server.oauth_settings['lti_endpoint'] in self.path
 
 
 class MockLTIServer(HTTPServer):
@@ -120,22 +123,13 @@ class MockLTIServer(HTTPServer):
     to POST requests to localhost.
     '''
 
-    def __init__(self, port_num, oauth={}):
+    def __init__(self, address):
         '''
         Initialize the mock XQueue server instance.
 
-        *port_num* is the localhost port to listen to
-
-        *grade_response_dict* is a dictionary that will be JSON-serialized
-            and sent in response to XQueue grading requests.
+        *address* is the (host, host's port to listen to) tuple.
         '''
-
-        self.clent_key = oauth.get('client_key', '')
-        self.clent_secret = oauth.get('client_secret', '')
-        self.check_oauth()
-
         handler = MockLTIRequestHandler
-        address = ('', port_num)
         HTTPServer.__init__(self, address, handler)
 
     def shutdown(self):
@@ -144,15 +138,34 @@ class MockLTIServer(HTTPServer):
         '''
         # First call superclass shutdown()
         HTTPServer.shutdown(self)
-
         # We also need to manually close the socket
         self.socket.close()
 
-    def get_oauth_signature(self):
-        '''test'''
-        return self._signature
+    def check_oauth_signature(self, params, client_signature):
+        '''
+        Checks oauth signature from client.
+
+        `params` are params from post request except signature,
+        `client_signature` is signature from request.
+
+        Builds mocked request and verifies hmac-sha1 signing::
+            1. builds string to sign from `params`, `url` and `http_method`.
+            2. signs it with `client_secret` which comes from server settings.
+            3. obtains signature after sign and then compares it with request.signature
+            (request signature comes form client in request)
+
+        Returns `True` if signatures are correct, otherwise `False`.
+
+        '''
+        client_secret = unicode(self.oauth_settings['client_secret'])
+        url = self.oauth_settings['lti_base'] + self.oauth_settings['lti_endpoint']
+
+        request = mock.Mock()
+
+        request.params = [(unicode(k), unicode(v)) for k, v in params.items()]
+        request.uri = unicode(url)
+        request.http_method = u'POST'
+        request.signature = unicode(client_signature)
 
-    def check_oauth(self):
-        ''' generate oauth signature '''
-        self._signature = '12345'
+        return signature.verify_hmac_sha1(request, client_secret)