Provide ability to login using CAS

4 files changed, 135 insertions, 2 deletions

diff --git a/synapse/config/cas.py b/synapse/config/cas.py
new file mode 100644
index 0000000000..81d034e8f0
--- /dev/null
+++ b/synapse/config/cas.py
@@ -0,0 +1,39 @@
+# -*- coding: utf-8 -*-
+# Copyright 2015 OpenMarket Ltd
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+
+from ._base import Config
+
+
+class CasConfig(Config):
+    """Cas Configuration
+
+    cas_server_url: URL of CAS server
+    """
+
+    def read_config(self, config):
+        cas_config = config.get("cas_config", None)
+        if cas_config:
+            self.cas_enabled = True
+            self.cas_server_url = cas_config["server_url"]
+        else:
+            self.cas_enabled = False
+            self.cas_server_url = None
+
+    def default_config(self, config_dir_path, server_name, **kwargs):
+        return """
+        # Enable CAS for registration and login.
+        #cas_config:
+        #   server_url: "https://cas-server.com"
+        """
diff --git a/synapse/config/homeserver.py b/synapse/config/homeserver.py
index d77f045406..3039f3c0bf 100644
--- a/synapse/config/homeserver.py
+++ b/synapse/config/homeserver.py
@@ -26,12 +26,13 @@ from .metrics import MetricsConfig
 from .appservice import AppServiceConfig
 from .key import KeyConfig
 from .saml2 import SAML2Config
+from .cas import CasConfig
 
 
 class HomeServerConfig(TlsConfig, ServerConfig, DatabaseConfig, LoggingConfig,
                        RatelimitConfig, ContentRepositoryConfig, CaptchaConfig,
                        VoipConfig, RegistrationConfig, MetricsConfig,
-                       AppServiceConfig, KeyConfig, SAML2Config, ):
+                       AppServiceConfig, KeyConfig, SAML2Config, CasConfig):
     pass
 
 
diff --git a/synapse/handlers/auth.py b/synapse/handlers/auth.py
index 793b3fcd8b..0ad28c4948 100644
--- a/synapse/handlers/auth.py
+++ b/synapse/handlers/auth.py
@@ -296,6 +296,37 @@ class AuthHandler(BaseHandler):
         defer.returnValue((user_id, access_token, refresh_token))
 
     @defer.inlineCallbacks
+    def login_with_cas_user_id(self, user_id):
+        """
+        Authenticates the user with the given user ID, intended to have been captured from a CAS response
+
+        Args:
+            user_id (str): User ID
+        Returns:
+            A tuple of:
+              The user's ID.
+              The access token for the user's session.
+              The refresh token for the user's session.
+        Raises:
+            StoreError if there was a problem storing the token.
+            LoginError if there was an authentication problem.
+        """
+        user_id, ignored = yield self._find_user_id_and_pwd_hash(user_id)
+
+        logger.info("Logging in user %s", user_id)
+        access_token = yield self.issue_access_token(user_id)
+        refresh_token = yield self.issue_refresh_token(user_id)
+        defer.returnValue((user_id, access_token, refresh_token))
+
+    @defer.inlineCallbacks
+    def does_user_exist(self, user_id):
+        try:
+            yield self._find_user_id_and_pwd_hash(user_id)
+            defer.returnValue(True)
+        except LoginError:
+            defer.returnValue(False)
+
+    @defer.inlineCallbacks
     def _find_user_id_and_pwd_hash(self, user_id):
         """Checks to see if a user with the given id exists. Will check case
         insensitively, but will throw if there are multiple inexact matches.
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
index e580f71964..56e5cf79fe 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -15,7 +15,7 @@
 
 from twisted.internet import defer
 
-from synapse.api.errors import SynapseError
+from synapse.api.errors import SynapseError, LoginError, Codes
 from synapse.types import UserID
 from base import ClientV1RestServlet, client_path_pattern
 
@@ -27,6 +27,9 @@ from saml2 import BINDING_HTTP_POST
 from saml2 import config
 from saml2.client import Saml2Client
 
+import xml.etree.ElementTree as ET
+import requests
+
 
 logger = logging.getLogger(__name__)
 
@@ -35,16 +38,23 @@ class LoginRestServlet(ClientV1RestServlet):
     PATTERN = client_path_pattern("/login$")
     PASS_TYPE = "m.login.password"
     SAML2_TYPE = "m.login.saml2"
+    CAS_TYPE = "m.login.cas"
 
     def __init__(self, hs):
         super(LoginRestServlet, self).__init__(hs)
         self.idp_redirect_url = hs.config.saml2_idp_redirect_url
         self.saml2_enabled = hs.config.saml2_enabled
+        self.cas_enabled = hs.config.cas_enabled
+
+        self.cas_server_url = hs.config.cas_server_url
+        self.servername = hs.config.server_name
 
     def on_GET(self, request):
         flows = [{"type": LoginRestServlet.PASS_TYPE}]
         if self.saml2_enabled:
             flows.append({"type": LoginRestServlet.SAML2_TYPE})
+        if self.cas_enabled:
+            flows.append({"type": LoginRestServlet.CAS_TYPE})
         return (200, {"flows": flows})
 
     def on_OPTIONS(self, request):
@@ -67,6 +77,12 @@ class LoginRestServlet(ClientV1RestServlet):
                     "uri": "%s%s" % (self.idp_redirect_url, relay_state)
                 }
                 defer.returnValue((200, result))
+            elif self.cas_enabled and (login_submission["type"] == LoginRestServlet.CAS_TYPE):
+                url = "%s/proxyValidate" % (self.cas_server_url)
+                parameters = {"ticket": login_submission["ticket"], "service": login_submission["service"]}
+                response = requests.get(url, verify=False, params=parameters)
+                result = yield self.do_cas_login(response.text)
+                defer.returnValue(result)
             else:
                 raise SynapseError(400, "Bad login type.")
         except KeyError:
@@ -100,6 +116,41 @@ class LoginRestServlet(ClientV1RestServlet):
 
         defer.returnValue((200, result))
 
+    @defer.inlineCallbacks
+    def do_cas_login(self, cas_response_body):
+        root = ET.fromstring(cas_response_body)
+        if not root.tag.endswith("serviceResponse"):
+            raise LoginError(401, "Invalid CAS response", errcode=Codes.UNAUTHORIZED)
+        if not root[0].tag.endswith("authenticationSuccess"):
+            raise LoginError(401, "Unsuccessful CAS response", errcode=Codes.UNAUTHORIZED)
+        for child in root[0]:
+            if child.tag.endswith("user"):
+                user = child.text
+                user_id = "@%s:%s" % (user, self.servername)
+                auth_handler = self.handlers.auth_handler
+                user_exists = yield auth_handler.does_user_exist(user_id)
+                if user_exists:
+                    user_id, access_token, refresh_token = yield auth_handler.login_with_cas_user_id(user_id)
+                    result = {
+                        "user_id": user_id,  # may have changed
+                        "access_token": access_token,
+                        "refresh_token": refresh_token,
+                        "home_server": self.hs.hostname,
+                    }
+
+                else:
+                    user_id, access_token = yield self.handlers.registration_handler.register(localpart=user)
+                    result = {
+                        "user_id": user_id,  # may have changed
+                        "access_token": access_token,
+                        "home_server": self.hs.hostname,
+                    }
+
+            defer.returnValue((200, result))
+
+
+        raise LoginError(401, "Invalid CAS response", errcode=Codes.UNAUTHORIZED)
+
 
 class LoginFallbackRestServlet(ClientV1RestServlet):
     PATTERN = client_path_pattern("/login/fallback$")
@@ -173,6 +224,15 @@ class SAML2RestServlet(ClientV1RestServlet):
             defer.returnValue(None)
         defer.returnValue((200, {"status": "not_authenticated"}))
 
+class CasRestServlet(ClientV1RestServlet):
+    PATTERN = client_path_pattern("/login/cas")
+
+    def __init__(self, hs):
+        super(CasRestServlet, self).__init__(hs)
+        self.cas_server_url = hs.config.cas_server_url
+
+    def on_GET(self, request):
+        return (200, {"serverUrl": self.cas_server_url})
 
 def _parse_json(request):
     try:
@@ -188,4 +248,6 @@ def register_servlets(hs, http_server):
     LoginRestServlet(hs).register(http_server)
     if hs.config.saml2_enabled:
         SAML2RestServlet(hs).register(http_server)
+    if hs.config.cas_enabled:
+        CasRestServlet(hs).register(http_server)
     # TODO PasswordResetRestServlet(hs).register(http_server)