Implements REMOTE_USER authentication support.

Adds support for non-identity authentication via REMOTE_USER environ
context variable thereby permitting external services (paste pipeline,
web fronting or other) to authenticate a request.

Also fixes a pep8 issue.

This change is in support for blueprint
pluggable-identity-authentication-handlers

Change-Id: Ib0a36b14f135dd87601e3c6d28f7874193d66b34

3 files changed, 116 insertions, 12 deletions

diff --git a/keystone/common/wsgi.py b/keystone/common/wsgi.py
index 9b42491d..39529bc9 100644
--- a/keystone/common/wsgi.py
+++ b/keystone/common/wsgi.py
@@ -199,6 +199,10 @@ class Application(BaseApplication):
         context = req.environ.get(CONTEXT_ENV, {})
         context['query_string'] = dict(req.params.iteritems())
         params = req.environ.get(PARAMS_ENV, {})
+        if 'REMOTE_USER' in req.environ:
+            context['REMOTE_USER'] = req.environ['REMOTE_USER']
+        elif context.get('REMOTE_USER', None) is not None:
+            del context['REMOTE_USER']
         params.update(arg_dict)
 
         # TODO(termie): do some basic normalization on methods
diff --git a/keystone/service.py b/keystone/service.py
index 4cc4ad26..b6443a70 100644
--- a/keystone/service.py
+++ b/keystone/service.py
@@ -289,6 +289,18 @@ class TokenController(wsgi.Application):
             raise exception.ValidationError(attribute='auth',
                                             target='request body')
 
+        if auth is None:
+            auth = {}
+        remote_auth = False
+        if 'REMOTE_USER' in context and not 'token' in auth:
+            # authenticated external request
+            remote_auth = True
+
+            if 'passwordCredentials' not in auth:
+                auth['passwordCredentials'] = {}
+            auth['passwordCredentials']['username'] = context.get(
+                'REMOTE_USER', None)
+
         if 'passwordCredentials' in auth:
             user_id = auth['passwordCredentials'].get('userId', None)
             username = auth['passwordCredentials'].get('username', '')
@@ -300,6 +312,10 @@ class TokenController(wsgi.Application):
                     attribute='username or userId',
                     target='passwordCredentials')
 
+            tenant_ref = None
+            user_ref = None
+            metadata_ref = {}
+
             if username:
                 try:
                     user_ref = self.identity_api.get_user_by_name(
@@ -308,7 +324,7 @@ class TokenController(wsgi.Application):
                 except exception.UserNotFound:
                     raise exception.Unauthorized()
 
-            if not password:
+            if not password and not remote_auth:
                 raise exception.ValidationError(
                     attribute='password',
                     target='passwordCredentials')
@@ -324,11 +340,30 @@ class TokenController(wsgi.Application):
                     raise exception.Unauthorized()
 
             try:
-                auth_info = self.identity_api.authenticate(context=context,
-                                                           user_id=user_id,
-                                                           password=password,
-                                                           tenant_id=tenant_id)
-                (user_ref, tenant_ref, metadata_ref) = auth_info
+                if not remote_auth:
+                    # local identity authentication required
+                    auth_info = self.identity_api.authenticate(
+                        context=context,
+                        user_id=user_id,
+                        password=password,
+                        tenant_id=tenant_id)
+                    (user_ref, tenant_ref, metadata_ref) = auth_info
+                else:
+                    # remote authentication already performed
+                    if not user_ref:
+                        user_ref = self.identity_api.get_user(
+                            self.identity_api,
+                            user_id)
+                    if tenant_id:
+                        if not tenant_ref:
+                            tenant_ref = self.identity_api.get_tenant(
+                                self.identity_api,
+                                tenant_id)
+                        metadata_ref = self.identity_api.get_metadata(
+                            self.identity_api,
+                            user_id,
+                            tenant_id)
+                    auth_info = (user_ref, tenant_ref, metadata_ref)
 
                 # If the user is disabled don't allow them to authenticate
                 if not user_ref.get('enabled', True):
diff --git a/tests/test_service.py b/tests/test_service.py
index 979e9472..775b2ca7 100644
--- a/tests/test_service.py
+++ b/tests/test_service.py
@@ -12,10 +12,13 @@
 # License for the specific language governing permissions and limitations
 # under the License.
 
+import default_fixtures
+
 from keystone import exception
 from keystone import identity
 from keystone import service
 from keystone import test
+from keystone.identity.backends import kvs as kvs_identity
 
 
 class FakeIdentityManager(object):
@@ -34,33 +37,95 @@ class TokenControllerTest(test.TestCase):
         right exception."""
         body_dict = {'passwordCredentials': {}, 'tenantName': 'demo'}
         self.assertRaises(exception.ValidationError, self.api.authenticate,
-                          None, body_dict)
+                          {}, body_dict)
 
     def test_authenticate_no_username(self):
         """Verify skipping username raises the right exception."""
         body_dict = {'passwordCredentials': {'password': 'pass'},
                      'tenantName': 'demo'}
         self.assertRaises(exception.ValidationError, self.api.authenticate,
-                          None, body_dict)
+                          {}, body_dict)
 
     def test_authenticate_no_password(self):
         """Verify skipping password raises the right exception."""
         body_dict = {'passwordCredentials': {'username': 'user1'},
                      'tenantName': 'demo'}
         self.assertRaises(exception.ValidationError, self.api.authenticate,
-                          None, body_dict)
+                          {}, body_dict)
 
     def test_authenticate_blank_request_body(self):
         """Verify sending empty json dict raises the right exception."""
         self.assertRaises(exception.ValidationError, self.api.authenticate,
-                          None, {})
+                          {}, {})
 
     def test_authenticate_blank_auth(self):
         """Verify sending blank 'auth' raises the right exception."""
         self.assertRaises(exception.ValidationError, self.api.authenticate,
-                          None, {'auth': {}})
+                          {}, {'auth': {}})
 
     def test_authenticate_invalid_auth_content(self):
         """Verify sending invalid 'auth' raises the right exception."""
         self.assertRaises(exception.ValidationError, self.api.authenticate,
-                          None, {'auth': 'abcd'})
+                          {}, {'auth': 'abcd'})
+
+
+class RemoteUserTest(test.TestCase):
+    def setUp(self):
+        super(RemoteUserTest, self).setUp()
+        self.identity_api = kvs_identity.Identity()
+        self.load_fixtures(default_fixtures)
+        self.api = service.TokenController()
+
+    def _build_user_auth(self, username, passwd, tenant):
+        auth_json = {'passwordCredentials': {}}
+        if username is not None:
+            auth_json['passwordCredentials']['username'] = username
+        if passwd is not None:
+            auth_json['passwordCredentials']['password'] = passwd
+        if tenant is not None:
+            auth_json['tenantName'] = tenant
+        return auth_json
+
+    def assertEqualTokens(self, a, b):
+        def normalize(token):
+            token['access']['token']['id'] = 'dummy'
+            # truncate to eliminate timing problems
+            issued = token['access']['token']['issued_at']
+            token['access']['token']['issued_at'] = issued[:-8]
+            # truncate to eliminate timing problems
+            expires = token['access']['token']['expires']
+            token['access']['token']['expires'] = expires[:-3]
+            return token
+        return self.assertDictEqual(normalize(a), normalize(b))
+
+    def test_unscoped_remote_authn(self):
+        local_token = self.api.authenticate(
+            {},
+            self._build_user_auth('FOO', 'foo2', None))
+        remote_token = self.api.authenticate(
+            {'REMOTE_USER': 'FOO'},
+            self._build_user_auth('FOO', 'nosir', None))
+        self.assertEqualTokens(local_token, remote_token)
+
+    def test_unscoped_remote_authn_jsonless(self):
+        self.assertRaises(
+            exception.ValidationError,
+            self.api.authenticate,
+            {'REMOTE_USER': 'FOO'},
+            None)
+
+    def test_scoped_remote_authn(self):
+        local_token = self.api.authenticate(
+            {},
+            self._build_user_auth('FOO', 'foo2', 'BAR'))
+        remote_token = self.api.authenticate(
+            {'REMOTE_USER': 'FOO'},
+            self._build_user_auth('FOO', 'nosir', 'BAR'))
+        self.assertEqualTokens(local_token, remote_token)
+
+    def test_scoped_remote_authn_invalid_user(self):
+        self.assertRaises(
+            exception.Unauthorized,
+            self.api.authenticate,
+            {'REMOTE_USER': 'FOOZBALL'},
+            self._build_user_auth('FOO', 'nosir', 'BAR'))