Add support for icons for identity providers

Author: richvdh

docs/sample_config.yaml

@@ -1723,6 +1723,10 @@ saml2_config:
 #   idp_name: A user-facing name for this identity provider, which is used to
 #       offer the user a choice of login mechanisms.
 #
+#   idp_icon: An optional icon for this identity provider, which is presented
+#       by identity picker pages. If given, must be an MXC URI of the format
+#       mxc://<server-name>/<media-id>
+#
 #   discover: set to 'false' to disable the use of the OIDC discovery mechanism
 #       to discover endpoints. Defaults to true.
 #

synapse/config/oidc_config.py

@@ -23,6 +23,7 @@
 from synapse.python_dependencies import DependencyException, check_requirements
 from synapse.types import Collection, JsonDict
 from synapse.util.module_loader import load_module
+from synapse.util.stringutils import parse_and_validate_mxc_uri
 
 from ._base import Config, ConfigError
 
@@ -68,6 +69,10 @@ def generate_config_section(self, config_dir_path, server_name, **kwargs):
         #   idp_name: A user-facing name for this identity provider, which is used to
         #       offer the user a choice of login mechanisms.
         #
+        #   idp_icon: An optional icon for this identity provider, which is presented
+        #       by identity picker pages. If given, must be an MXC URI of the format
+        #       mxc://<server-name>/<media-id>
+        #
         #   discover: set to 'false' to disable the use of the OIDC discovery mechanism
         #       to discover endpoints. Defaults to true.
         #
@@ -209,6 +214,7 @@ def generate_config_section(self, config_dir_path, server_name, **kwargs):
     "properties": {
         "idp_id": {"type": "string", "minLength": 1, "maxLength": 128},
         "idp_name": {"type": "string"},
+        "idp_icon": {"type": "string"},
         "discover": {"type": "boolean"},
         "issuer": {"type": "string"},
         "client_id": {"type": "string"},
@@ -338,9 +344,20 @@ def _parse_oidc_config_dict(
             config_path + ("idp_id",),
         )
 
+    # MSC2858 also specifies that the idp_icon must be a valid MXC uri
+    idp_icon = oidc_config.get("idp_icon")
+    if idp_icon is not None:
+        try:
+            parse_and_validate_mxc_uri(idp_icon)
+        except ValueError as e:
+            raise ConfigError(
+                "idp_icon must be a valid MXC URI", config_path + ("idp_icon",)
+            ) from e
+
     return OidcProviderConfig(
         idp_id=idp_id,
         idp_name=oidc_config.get("idp_name", "OIDC"),
+        idp_icon=idp_icon,
         discover=oidc_config.get("discover", True),
         issuer=oidc_config["issuer"],
         client_id=oidc_config["client_id"],
@@ -368,6 +385,9 @@ class OidcProviderConfig:
     # user-facing name for this identity provider.
     idp_name = attr.ib(type=str)
 
+    # Optional MXC URI for icon for this IdP.
+    idp_icon = attr.ib(type=Optional[str])
+
     # whether the OIDC discovery mechanism is used to discover endpoints
     discover = attr.ib(type=bool)
 

synapse/handlers/oidc_handler.py

@@ -271,6 +271,9 @@ def __init__(
         # user-facing name of this auth provider
         self.idp_name = provider.idp_name
 
+        # MXC URI for icon for this auth provider
+        self.idp_icon = provider.idp_icon
+
         self._sso_handler = hs.get_sso_handler()
 
         self._sso_handler.register_identity_provider(self)

synapse/handlers/sso.py

@@ -75,6 +75,11 @@ def idp_id(self) -> str:
     def idp_name(self) -> str:
         """User-facing name for this provider"""
 
+    @property
+    def idp_icon(self) -> Optional[str]:
+        """Optional MXC URI for user-facing icon"""
+        return None
+
     @abc.abstractmethod
     async def handle_redirect_request(
         self,

synapse/res/templates/sso_login_idp_picker.html

@@ -17,6 +17,9 @@ <h1 id="title">{{server_name | e}} Login</h1>
                     <li>
                         <input type="radio" name="idp" id="prov{{loop.index}}" value="{{p.idp_id}}">
                         <label for="prov{{loop.index}}">{{p.idp_name | e}}</label>
+{% if p.idp_icon %}
+                        <img src="{{p.idp_icon | mxc_to_http(32, 32)}}"/>
+{% endif %}
                     </li>
 {% endfor %}
                 </ul>

synapse/util/stringutils.py

@@ -130,6 +130,27 @@ def parse_and_validate_server_name(server_name: str) -> Tuple[str, Optional[int]
     return host, port
 
 
+def parse_and_validate_mxc_uri(mxc: str) -> Tuple[str, Optional[int], str]:
+    """Parse the given string as an MXC URI
+
+    Checks that the "server name" part is a valid server name
+
+    Args:
+        mxc: the (alleged) MXC URI to be checked
+    Returns:
+        hostname, port, media id
+    Raises:
+        ValueError if the URI cannot be parsed
+    """
+    m = mxc_re.match(mxc)
+    if not m:
+        raise ValueError("mxc URI %r did not match expected format" % (mxc,))
+    server_name = m.group(1)
+    media_id = m.group(2)
+    host, port = parse_and_validate_server_name(server_name)
+    return host, port, media_id
+
+
 def shortstr(iterable: Iterable, maxitems: int = 5) -> str:
     """If iterable has maxitems or fewer, return the stringification of a list
     containing those items.