Add module API callbacks for adding and deleting local 3PID associations

changelog.d/15044.feature

@@ -0,0 +1 @@
+Add two new Third Party Rules module API callbacks: [`on_add_user_third_party_identifier`](https://matrix-org.github.io/synapse/v1.78/modules/third_party_rules_callbacks.html#on_add_user_third_party_identifier) and [`on_remove_user_third_party_identifier`](https://matrix-org.github.io/synapse/v1.78/modules/third_party_rules_callbacks.html#on_remove_user_third_party_identifier).

docs/modules/third_party_rules_callbacks.md

@@ -251,6 +251,13 @@ If multiple modules implement this callback, Synapse runs them all in order.
 
 _First introduced in Synapse v1.56.0_
 
+**<span style="color:red">
+This callback is deprecated in favour of the `on_add_user_third_party_identifier` callback, which
+features nearly the same functionality. The only difference is that while `on_threepid_bind`
+was called *after* a third-party ID was associated with a user's account on the homeserver,
+`on_add_user_third_party_identifier` is called just *before* a third-party ID is associated.
+</span>**
+
 ```python
 async def on_threepid_bind(user_id: str, medium: str, address: str) -> None:
 ```
@@ -265,6 +272,44 @@ server_.
 
 If multiple modules implement this callback, Synapse runs them all in order.
 
+### `on_add_user_third_party_identifier`
+
+_First introduced in Synapse v1.78.0_
+
+```python
+async def on_add_user_third_party_identifier(user_id: str, medium: str, address: str) -> None:
+```
+
+Called just before creating an association between a user and a third-party identifier
+(email address, phone number). The module is given the Matrix ID of the user the
+association is for, as well as the medium (`email` or `msisdn`) and address of the
+third-party identifier (i.e. an email address).
+
+Note that this callback is _not_ called if a user attempts to bind their third-party identifier
+to an identity server (via a call to [`POST
+/_matrix/client/v3/account/3pid/bind`](https://spec.matrix.org/v1.5/client-server-api/#post_matrixclientv3account3pidbind)).
+
+If multiple modules implement this callback, Synapse runs them all in order.
+
+### `on_remove_user_third_party_identifier`
+
+_First introduced in Synapse v1.78.0_
+
+```python
+async def on_remove_user_third_party_identifier(user_id: str, medium: str, address: str) -> None:
+```
+
+Called just before removing an association between a user and a third-party identifier
+(email address, phone number). The module is given the Matrix ID of the user the
+association is for, as well as the medium (`email` or `msisdn`) and address of the
+third-party identifier (i.e. an email address).
+
+Note that this callback is _not_ called if a user attempts to unbind their third-party
+identifier from an identity server (via a call to [`POST
+/_matrix/client/v3/account/3pid/unbind`](https://spec.matrix.org/v1.5/client-server-api/#post_matrixclientv3account3pidunbind)).
+
+If multiple modules implement this callback, Synapse runs them all in order.
+
 ## Example
 
 The example below is a module that implements the third-party rules callback
@@ -297,4 +342,4 @@ class EventCensorer:
         )
         event_dict["content"] = new_event_content
         return event_dict
-```
+```

docs/upgrade.md

@@ -97,6 +97,32 @@ admin API with an identical endpoint at `/_synapse/admin/v1/media/delete`. Pleas
 update your tooling to use the new endpoint. The deprecated version will be removed
 in a future release.
 
+## The `on_threepid_bind` module callback method has been deprecated
+
+The [`on_threepid_bind`](modules/third_party_rules_callbacks.md#on_threepid_bind) "third-party rules"
+Synapse module callback method has been deprecated
+in favour of a new module method,
+[`on_add_user_third_party_identifier`](modules/third_party_rules_callbacks.md#on_add_user_third_party_identifier).
+`on_threepid_bind` will be removed in a future version of Synapse. You should check whether any Synapse
+modules in use in your deployment are making use of `on_threepid_bind`, and update them where possible.
+
+The arguments and functionality of the new method are nearly the same; `on_threepid_bind` was called
+directly *after* a user adds a third-party identifier (email, phone number) to their account, while
+`on_add_user_third_party_identifier` is called just *before* a user adds a third-party identifier.
+
+The justification behind the swap in logical ordering is that `on_add_user_third_party_identifier`
+may be extended in the future to allow blocking a user from adding a third-party identifier to their
+account. The reason behind the name change is that the old method's name, `on_threepid_bind`, was
+misleading. A user is considered to "bind" their third-party ID to their Matrix ID only if they
+do so via an [identity server](https://spec.matrix.org/latest/identity-service-api/)
+(so that users on other homeservers may find them). But this method was not called in that case -
+it was only called when a user added a third-party identifier on the local homeserver.
+
+Module developers may also be interested in the related
+[`on_remove_user_third_party_identifier`](modules/third_party_rules_callbacks.md#on_remove_user_third_party_identifier)
+module callback method that was also added in Synapse v1.77.0. This new method is called when a
+user removes a third-party identifier from their account.
+
 # Upgrading to v1.76.0
 
 ## Faster joins are enabled by default

synapse/events/third_party_rules.py

@@ -45,6 +45,8 @@
 ON_PROFILE_UPDATE_CALLBACK = Callable[[str, ProfileInfo, bool, bool], Awaitable]
 ON_USER_DEACTIVATION_STATUS_CHANGED_CALLBACK = Callable[[str, bool, bool], Awaitable]
 ON_THREEPID_BIND_CALLBACK = Callable[[str, str, str], Awaitable]
+ON_ADD_USER_THIRD_PARTY_IDENTIFIER_CALLBACK = Callable[[str, str, str], Awaitable]
+ON_REMOVE_USER_THIRD_PARTY_IDENTIFIER_CALLBACK = Callable[[str, str, str], Awaitable]
 
 
 def load_legacy_third_party_event_rules(hs: "HomeServer") -> None:
@@ -174,6 +176,12 @@ def __init__(self, hs: "HomeServer"):
             ON_USER_DEACTIVATION_STATUS_CHANGED_CALLBACK
         ] = []
         self._on_threepid_bind_callbacks: List[ON_THREEPID_BIND_CALLBACK] = []
+        self._on_add_user_third_party_identifier_callbacks: List[
+            ON_ADD_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = []
+        self._on_remove_user_third_party_identifier_callbacks: List[
+            ON_REMOVE_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = []
 
     def register_third_party_rules_callbacks(
         self,
@@ -193,6 +201,12 @@ def register_third_party_rules_callbacks(
             ON_USER_DEACTIVATION_STATUS_CHANGED_CALLBACK
         ] = None,
         on_threepid_bind: Optional[ON_THREEPID_BIND_CALLBACK] = None,
+        on_add_user_third_party_identifier: Optional[
+            ON_ADD_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = None,
+        on_remove_user_third_party_identifier: Optional[
+            ON_REMOVE_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = None,
     ) -> None:
         """Register callbacks from modules for each hook."""
         if check_event_allowed is not None:
@@ -230,6 +244,11 @@ def register_third_party_rules_callbacks(
         if on_threepid_bind is not None:
             self._on_threepid_bind_callbacks.append(on_threepid_bind)
 
+        if on_add_user_third_party_identifier is not None:
+            self._on_add_user_third_party_identifier_callbacks.append(
+                on_add_user_third_party_identifier
+            )
+
     async def check_event_allowed(
         self,
         event: EventBase,
@@ -513,6 +532,9 @@ async def on_threepid_bind(self, user_id: str, medium: str, address: str) -> Non
         local homeserver, not when it's created on an identity server (and then kept track
         of so that it can be unbound on the same IS later on).
 
+        THIS MODULE CALLBACK METHOD HAS BEEN DEPRECATED. Please use the
+        `on_add_user_third_party_identifier` callback method instead.
+
         Args:
             user_id: the user being associated with the threepid.
             medium: the threepid's medium.
@@ -525,3 +547,43 @@ async def on_threepid_bind(self, user_id: str, medium: str, address: str) -> Non
                 logger.exception(
                     "Failed to run module API callback %s: %s", callback, e
                 )
+
+    async def on_add_user_third_party_identifier(
+        self, user_id: str, medium: str, address: str
+    ) -> None:
+        """Called when an association between a user's Matrix ID and a third-party ID
+        (email, phone number) is about to be registered on the homeserver.
+
+        Args:
+            user_id: The User ID to include in the association.
+            medium: The medium of the third-party ID (email, msisdn).
+            address: The address of the third-party ID (i.e. an email address).
+        """
+        for callback in self._on_add_user_third_party_identifier_callbacks:
+            try:
+                await callback(user_id, medium, address)
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )
+
+    async def on_remove_user_third_party_identifier(
+        self, user_id: str, medium: str, address: str
+    ) -> None:
+        """Called when an association between a user's Matrix ID and a third-party ID
+        (email, phone number) is about to be removed on the homeserver. This is called
+        *after* any known bindings on identity servers for this association have been
+        removed.
+
+        Args:
+            user_id: The User ID including in the association to remove.
+            medium: The medium of the third-party ID (email, msisdn).
+            address: The address of the third-party ID (i.e. an email address).
+        """
+        for callback in self._on_remove_user_third_party_identifier_callbacks:
+            try:
+                await callback(user_id, medium, address)
+            except Exception as e:
+                logger.exception(
+                    "Failed to run module API callback %s: %s", callback, e
+                )

synapse/handlers/auth.py

@@ -1543,6 +1543,17 @@ async def delete_access_tokens_for_user(
     async def add_threepid(
         self, user_id: str, medium: str, address: str, validated_at: int
     ) -> None:
+        """
+        Adds an association between a user's Matrix ID and a third-party ID (email,
+        phone number).
+
+        Args:
+            user_id: The ID of the user to associate.
+            medium: The medium of the third-party ID (email, msisdn).
+            address: The address of the third-party ID (i.e. an email address).
+            validated_at: The timestamp in ms of when the validation that the user owns
+                this third-party ID occurred.
+        """
         # check if medium has a valid value
         if medium not in ["email", "msisdn"]:
             raise SynapseError(
@@ -1563,46 +1574,64 @@ async def add_threepid(
         if medium == "email":
             address = canonicalise_email(address)
 
-        await self.store.user_add_threepid(
-            user_id, medium, address, validated_at, self.hs.get_clock().time_msec()
+        # Inform Synapse modules that a 3PID association is about to be created.
+        await self._third_party_rules.on_add_user_third_party_identifier(
+            user_id, medium, address
         )
 
+        try:
+            await self.store.user_add_threepid(
+                user_id, medium, address, validated_at, self.hs.get_clock().time_msec()
+            )
+        except Exception:
+            # We failed to store the association, but told Synapse modules otherwise.
+            # Tell them that the association was deleted.
+            await self._third_party_rules.on_remove_user_third_party_identifier(
+                user_id, medium, address
+            )
+            raise
+
+        # Deprecated method for informing Synapse modules that a 3PID association
+        # has successfully been created.
         await self._third_party_rules.on_threepid_bind(user_id, medium, address)
 
-    async def delete_threepid(
-        self, user_id: str, medium: str, address: str, id_server: Optional[str] = None
-    ) -> bool:
-        """Attempts to unbind the 3pid on the identity servers and deletes it
-        from the local database.
+    async def delete_local_threepid(
+        self, user_id: str, medium: str, address: str
+    ) -> None:
+        """Deletes an association between a third-party ID and a user ID from the local
+        database. This method does not unbind the association from any identity servers.
+
+        If `medium` is 'email' and a pusher is associated with this third-party ID, the
+        pusher will also be deleted.
 
         Args:
             user_id: ID of user to remove the 3pid from.
             medium: The medium of the 3pid being removed: "email" or "msisdn".
             address: The 3pid address to remove.
-            id_server: Use the given identity server when unbinding
-                any threepids. If None then will attempt to unbind using the
-                identity server specified when binding (if known).
-
-        Returns:
-            Returns True if successfully unbound the 3pid on
-            the identity server, False if identity server doesn't support the
-            unbind API.
         """
-
         # 'Canonicalise' email addresses as per above
         if medium == "email":
             address = canonicalise_email(address)
 
-        result = await self.hs.get_identity_handler().try_unbind_threepid(
-            user_id, medium, address, id_server
+        # Inform Synapse modules that a 3PID association is about to be deleted.
+        await self._third_party_rules.on_remove_user_third_party_identifier(
+            user_id, medium, address
         )
 
-        await self.store.user_delete_threepid(user_id, medium, address)
+        try:
+            await self.store.user_delete_threepid(user_id, medium, address)
+        except Exception:
+            # We failed to store the association, but told Synapse modules otherwise.
+            # Tell them that the association has come back.
+            await self._third_party_rules.on_add_user_third_party_identifier(
+                user_id, medium, address
+            )
+            raise
+
         if medium == "email":
             await self.store.delete_pusher_by_app_id_pushkey_user_id(
                 app_id="m.email", pushkey=address, user_id=user_id
             )
-        return result
 
     async def hash(self, password: str) -> str:
         """Computes a secure hash of password.

synapse/handlers/deactivate_account.py

@@ -100,26 +100,28 @@ async def deactivate_account(
         # unbinding
         identity_server_supports_unbinding = True
 
-        # Retrieve the 3PIDs this user has bound to an identity server
-        threepids = await self.store.user_get_bound_threepids(user_id)
-
-        for threepid in threepids:
+        # Attempt to unbind any known bound threepids to this account from identity
+        # server(s).
+        bound_threepids = await self.store.user_get_bound_threepids(user_id)
+        for threepid in bound_threepids:
             try:
                 result = await self._identity_handler.try_unbind_threepid(
                     user_id, threepid["medium"], threepid["address"], id_server
                 )
-                identity_server_supports_unbinding &= result
             except Exception:
                 # Do we want this to be a fatal error or should we carry on?
                 logger.exception("Failed to remove threepid from ID server")
                 raise SynapseError(400, "Failed to remove threepid from ID server")
-            await self.store.user_delete_threepid(
+
+            identity_server_supports_unbinding &= result
+
+        # Remove any local threepid associations for this account.
+        local_threepids = await self.store.user_get_threepids(user_id)
+        for threepid in local_threepids:
+            await self._auth_handler.delete_local_threepid(
                 user_id, threepid["medium"], threepid["address"]
             )
 
-        # Remove all 3PIDs this user has bound to the homeserver
-        await self.store.user_delete_threepids(user_id)
-
         # delete any devices belonging to the user, which will also
         # delete corresponding access tokens.
         await self._device_handler.delete_all_devices_for_user(user_id)

synapse/module_api/__init__.py

@@ -64,9 +64,11 @@
     CHECK_EVENT_ALLOWED_CALLBACK,
     CHECK_THREEPID_CAN_BE_INVITED_CALLBACK,
     CHECK_VISIBILITY_CAN_BE_MODIFIED_CALLBACK,
+    ON_ADD_USER_THIRD_PARTY_IDENTIFIER_CALLBACK,
     ON_CREATE_ROOM_CALLBACK,
     ON_NEW_EVENT_CALLBACK,
     ON_PROFILE_UPDATE_CALLBACK,
+    ON_REMOVE_USER_THIRD_PARTY_IDENTIFIER_CALLBACK,
     ON_THREEPID_BIND_CALLBACK,
     ON_USER_DEACTIVATION_STATUS_CHANGED_CALLBACK,
 )
@@ -357,6 +359,12 @@ def register_third_party_rules_callbacks(
             ON_USER_DEACTIVATION_STATUS_CHANGED_CALLBACK
         ] = None,
         on_threepid_bind: Optional[ON_THREEPID_BIND_CALLBACK] = None,
+        on_add_user_third_party_identifier: Optional[
+            ON_ADD_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = None,
+        on_remove_user_third_party_identifier: Optional[
+            ON_REMOVE_USER_THIRD_PARTY_IDENTIFIER_CALLBACK
+        ] = None,
     ) -> None:
         """Registers callbacks for third party event rules capabilities.
 
@@ -373,6 +381,8 @@ def register_third_party_rules_callbacks(
             on_profile_update=on_profile_update,
             on_user_deactivation_status_changed=on_user_deactivation_status_changed,
             on_threepid_bind=on_threepid_bind,
+            on_add_user_third_party_identifier=on_add_user_third_party_identifier,
+            on_remove_user_third_party_identifier=on_remove_user_third_party_identifier,
         )
 
     def register_presence_router_callbacks(