Move lookup-related functions from RoomMemberHandler to IdentityHandler (#5978)

Just to have all the methods that make calls to identity services in one place.

2 files changed, 359 insertions, 364 deletions

diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index 6d42a1aed8..ba99ddf76d 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -21,11 +21,15 @@ import logging
 import urllib
 
 from canonicaljson import json
+from signedjson.key import decode_verify_key_bytes
+from signedjson.sign import verify_signed_json
+from unpaddedbase64 import decode_base64
 
 from twisted.internet import defer
 from twisted.internet.error import TimeoutError
 
 from synapse.api.errors import (
+    AuthError,
     CodeMessageException,
     Codes,
     HttpResponseException,
@@ -33,12 +37,15 @@ from synapse.api.errors import (
 )
 from synapse.config.emailconfig import ThreepidBehaviour
 from synapse.http.client import SimpleHttpClient
+from synapse.util.hash import sha256_and_url_safe_base64
 from synapse.util.stringutils import random_string
 
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
+id_server_scheme = "https://"
+
 
 class IdentityHandler(BaseHandler):
     def __init__(self, hs):
@@ -557,6 +564,352 @@ class IdentityHandler(BaseHandler):
             logger.warning("Error contacting msisdn account_threepid_delegate: %s", e)
             raise SynapseError(400, "Error contacting the identity server")
 
+    @defer.inlineCallbacks
+    def lookup_3pid(self, id_server, medium, address, id_access_token=None):
+        """Looks up a 3pid in the passed identity server.
+
+        Args:
+            id_server (str): The server name (including port, if required)
+                of the identity server to use.
+            medium (str): The type of the third party identifier (e.g. "email").
+            address (str): The third party identifier (e.g. "foo@example.com").
+            id_access_token (str|None): The access token to authenticate to the identity
+                server with
+
+        Returns:
+            str|None: the matrix ID of the 3pid, or None if it is not recognized.
+        """
+        if id_access_token is not None:
+            try:
+                results = yield self._lookup_3pid_v2(
+                    id_server, id_access_token, medium, address
+                )
+                return results
+
+            except Exception as e:
+                # Catch HttpResponseExcept for a non-200 response code
+                # Check if this identity server does not know about v2 lookups
+                if isinstance(e, HttpResponseException) and e.code == 404:
+                    # This is an old identity server that does not yet support v2 lookups
+                    logger.warning(
+                        "Attempted v2 lookup on v1 identity server %s. Falling "
+                        "back to v1",
+                        id_server,
+                    )
+                else:
+                    logger.warning("Error when looking up hashing details: %s", e)
+                    return None
+
+        return (yield self._lookup_3pid_v1(id_server, medium, address))
+
+    @defer.inlineCallbacks
+    def _lookup_3pid_v1(self, id_server, medium, address):
+        """Looks up a 3pid in the passed identity server using v1 lookup.
+
+        Args:
+            id_server (str): The server name (including port, if required)
+                of the identity server to use.
+            medium (str): The type of the third party identifier (e.g. "email").
+            address (str): The third party identifier (e.g. "foo@example.com").
+
+        Returns:
+            str: the matrix ID of the 3pid, or None if it is not recognized.
+        """
+        try:
+            data = yield self.blacklisting_http_client.get_json(
+                "%s%s/_matrix/identity/api/v1/lookup" % (id_server_scheme, id_server),
+                {"medium": medium, "address": address},
+            )
+
+            if "mxid" in data:
+                if "signatures" not in data:
+                    raise AuthError(401, "No signatures on 3pid binding")
+                yield self._verify_any_signature(data, id_server)
+                return data["mxid"]
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
+        except IOError as e:
+            logger.warning("Error from v1 identity server lookup: %s" % (e,))
+
+        return None
+
+    @defer.inlineCallbacks
+    def _lookup_3pid_v2(self, id_server, id_access_token, medium, address):
+        """Looks up a 3pid in the passed identity server using v2 lookup.
+
+        Args:
+            id_server (str): The server name (including port, if required)
+                of the identity server to use.
+            id_access_token (str): The access token to authenticate to the identity server with
+            medium (str): The type of the third party identifier (e.g. "email").
+            address (str): The third party identifier (e.g. "foo@example.com").
+
+        Returns:
+            Deferred[str|None]: the matrix ID of the 3pid, or None if it is not recognised.
+        """
+        # Check what hashing details are supported by this identity server
+        try:
+            hash_details = yield self.blacklisting_http_client.get_json(
+                "%s%s/_matrix/identity/v2/hash_details" % (id_server_scheme, id_server),
+                {"access_token": id_access_token},
+            )
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
+
+        if not isinstance(hash_details, dict):
+            logger.warning(
+                "Got non-dict object when checking hash details of %s%s: %s",
+                id_server_scheme,
+                id_server,
+                hash_details,
+            )
+            raise SynapseError(
+                400,
+                "Non-dict object from %s%s during v2 hash_details request: %s"
+                % (id_server_scheme, id_server, hash_details),
+            )
+
+        # Extract information from hash_details
+        supported_lookup_algorithms = hash_details.get("algorithms")
+        lookup_pepper = hash_details.get("lookup_pepper")
+        if (
+            not supported_lookup_algorithms
+            or not isinstance(supported_lookup_algorithms, list)
+            or not lookup_pepper
+            or not isinstance(lookup_pepper, str)
+        ):
+            raise SynapseError(
+                400,
+                "Invalid hash details received from identity server %s%s: %s"
+                % (id_server_scheme, id_server, hash_details),
+            )
+
+        # Check if any of the supported lookup algorithms are present
+        if LookupAlgorithm.SHA256 in supported_lookup_algorithms:
+            # Perform a hashed lookup
+            lookup_algorithm = LookupAlgorithm.SHA256
+
+            # Hash address, medium and the pepper with sha256
+            to_hash = "%s %s %s" % (address, medium, lookup_pepper)
+            lookup_value = sha256_and_url_safe_base64(to_hash)
+
+        elif LookupAlgorithm.NONE in supported_lookup_algorithms:
+            # Perform a non-hashed lookup
+            lookup_algorithm = LookupAlgorithm.NONE
+
+            # Combine together plaintext address and medium
+            lookup_value = "%s %s" % (address, medium)
+
+        else:
+            logger.warning(
+                "None of the provided lookup algorithms of %s are supported: %s",
+                id_server,
+                supported_lookup_algorithms,
+            )
+            raise SynapseError(
+                400,
+                "Provided identity server does not support any v2 lookup "
+                "algorithms that this homeserver supports.",
+            )
+
+        # Authenticate with identity server given the access token from the client
+        headers = {"Authorization": create_id_access_token_header(id_access_token)}
+
+        try:
+            lookup_results = yield self.blacklisting_http_client.post_json_get_json(
+                "%s%s/_matrix/identity/v2/lookup" % (id_server_scheme, id_server),
+                {
+                    "addresses": [lookup_value],
+                    "algorithm": lookup_algorithm,
+                    "pepper": lookup_pepper,
+                },
+                headers=headers,
+            )
+        except TimeoutError:
+            raise SynapseError(500, "Timed out contacting identity server")
+        except Exception as e:
+            logger.warning("Error when performing a v2 3pid lookup: %s", e)
+            raise SynapseError(
+                500, "Unknown error occurred during identity server lookup"
+            )
+
+        # Check for a mapping from what we looked up to an MXID
+        if "mappings" not in lookup_results or not isinstance(
+            lookup_results["mappings"], dict
+        ):
+            logger.warning("No results from 3pid lookup")
+            return None
+
+        # Return the MXID if it's available, or None otherwise
+        mxid = lookup_results["mappings"].get(lookup_value)
+        return mxid
+
+    @defer.inlineCallbacks
+    def _verify_any_signature(self, data, server_hostname):
+        if server_hostname not in data["signatures"]:
+            raise AuthError(401, "No signature from server %s" % (server_hostname,))
+        for key_name, signature in data["signatures"][server_hostname].items():
+            try:
+                key_data = yield self.blacklisting_http_client.get_json(
+                    "%s%s/_matrix/identity/api/v1/pubkey/%s"
+                    % (id_server_scheme, server_hostname, key_name)
+                )
+            except TimeoutError:
+                raise SynapseError(500, "Timed out contacting identity server")
+            if "public_key" not in key_data:
+                raise AuthError(
+                    401, "No public key named %s from %s" % (key_name, server_hostname)
+                )
+            verify_signed_json(
+                data,
+                server_hostname,
+                decode_verify_key_bytes(
+                    key_name, decode_base64(key_data["public_key"])
+                ),
+            )
+            return
+
+    @defer.inlineCallbacks
+    def ask_id_server_for_third_party_invite(
+        self,
+        requester,
+        id_server,
+        medium,
+        address,
+        room_id,
+        inviter_user_id,
+        room_alias,
+        room_avatar_url,
+        room_join_rules,
+        room_name,
+        inviter_display_name,
+        inviter_avatar_url,
+        id_access_token=None,
+    ):
+        """
+        Asks an identity server for a third party invite.
+
+        Args:
+            requester (Requester)
+            id_server (str): hostname + optional port for the identity server.
+            medium (str): The literal string "email".
+            address (str): The third party address being invited.
+            room_id (str): The ID of the room to which the user is invited.
+            inviter_user_id (str): The user ID of the inviter.
+            room_alias (str): An alias for the room, for cosmetic notifications.
+            room_avatar_url (str): The URL of the room's avatar, for cosmetic
+                notifications.
+            room_join_rules (str): The join rules of the email (e.g. "public").
+            room_name (str): The m.room.name of the room.
+            inviter_display_name (str): The current display name of the
+                inviter.
+            inviter_avatar_url (str): The URL of the inviter's avatar.
+            id_access_token (str|None): The access token to authenticate to the identity
+                server with
+
+        Returns:
+            A deferred tuple containing:
+                token (str): The token which must be signed to prove authenticity.
+                public_keys ([{"public_key": str, "key_validity_url": str}]):
+                    public_key is a base64-encoded ed25519 public key.
+                fallback_public_key: One element from public_keys.
+                display_name (str): A user-friendly name to represent the invited
+                    user.
+        """
+        invite_config = {
+            "medium": medium,
+            "address": address,
+            "room_id": room_id,
+            "room_alias": room_alias,
+            "room_avatar_url": room_avatar_url,
+            "room_join_rules": room_join_rules,
+            "room_name": room_name,
+            "sender": inviter_user_id,
+            "sender_display_name": inviter_display_name,
+            "sender_avatar_url": inviter_avatar_url,
+        }
+
+        # Add the identity service access token to the JSON body and use the v2
+        # Identity Service endpoints if id_access_token is present
+        data = None
+        base_url = "%s%s/_matrix/identity" % (id_server_scheme, id_server)
+
+        if id_access_token:
+            key_validity_url = "%s%s/_matrix/identity/v2/pubkey/isvalid" % (
+                id_server_scheme,
+                id_server,
+            )
+
+            # Attempt a v2 lookup
+            url = base_url + "/v2/store-invite"
+            try:
+                data = yield self.blacklisting_http_client.post_json_get_json(
+                    url,
+                    invite_config,
+                    {"Authorization": create_id_access_token_header(id_access_token)},
+                )
+            except TimeoutError:
+                raise SynapseError(500, "Timed out contacting identity server")
+            except HttpResponseException as e:
+                if e.code != 404:
+                    logger.info("Failed to POST %s with JSON: %s", url, e)
+                    raise e
+
+        if data is None:
+            key_validity_url = "%s%s/_matrix/identity/api/v1/pubkey/isvalid" % (
+                id_server_scheme,
+                id_server,
+            )
+            url = base_url + "/api/v1/store-invite"
+
+            try:
+                data = yield self.blacklisting_http_client.post_json_get_json(
+                    url, invite_config
+                )
+            except TimeoutError:
+                raise SynapseError(500, "Timed out contacting identity server")
+            except HttpResponseException as e:
+                logger.warning(
+                    "Error trying to call /store-invite on %s%s: %s",
+                    id_server_scheme,
+                    id_server,
+                    e,
+                )
+
+            if data is None:
+                # Some identity servers may only support application/x-www-form-urlencoded
+                # types. This is especially true with old instances of Sydent, see
+                # https://github.com/matrix-org/sydent/pull/170
+                try:
+                    data = yield self.blacklisting_http_client.post_urlencoded_get_json(
+                        url, invite_config
+                    )
+                except HttpResponseException as e:
+                    logger.warning(
+                        "Error calling /store-invite on %s%s with fallback "
+                        "encoding: %s",
+                        id_server_scheme,
+                        id_server,
+                        e,
+                    )
+                    raise e
+
+        # TODO: Check for success
+        token = data["token"]
+        public_keys = data.get("public_keys", [])
+        if "public_key" in data:
+            fallback_public_key = {
+                "public_key": data["public_key"],
+                "key_validity_url": key_validity_url,
+            }
+        else:
+            fallback_public_key = public_keys[0]
+
+        if not public_keys:
+            public_keys.append(fallback_public_key)
+        display_name = data["display_name"]
+        return token, public_keys, fallback_public_key, display_name
+
 
 def create_id_access_token_header(id_access_token):
     """Create an Authorization header for passing to SimpleHttpClient as the header value
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 94cd0cf3ef..8abdb1b6e6 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -20,29 +20,19 @@ import logging
 
 from six.moves import http_client
 
-from signedjson.key import decode_verify_key_bytes
-from signedjson.sign import verify_signed_json
-from unpaddedbase64 import decode_base64
-
 from twisted.internet import defer
-from twisted.internet.error import TimeoutError
 
 from synapse import types
 from synapse.api.constants import EventTypes, Membership
-from synapse.api.errors import AuthError, Codes, HttpResponseException, SynapseError
-from synapse.handlers.identity import LookupAlgorithm, create_id_access_token_header
-from synapse.http.client import SimpleHttpClient
+from synapse.api.errors import AuthError, Codes, SynapseError
 from synapse.types import RoomID, UserID
 from synapse.util.async_helpers import Linearizer
 from synapse.util.distributor import user_joined_room, user_left_room
-from synapse.util.hash import sha256_and_url_safe_base64
 
 from ._base import BaseHandler
 
 logger = logging.getLogger(__name__)
 
-id_server_scheme = "https://"
-
 
 class RoomMemberHandler(object):
     # TODO(paul): This handler currently contains a messy conflation of
@@ -63,14 +53,10 @@ class RoomMemberHandler(object):
         self.auth = hs.get_auth()
         self.state_handler = hs.get_state_handler()
         self.config = hs.config
-        # We create a blacklisting instance of SimpleHttpClient for contacting identity
-        # servers specified by clients
-        self.simple_http_client = SimpleHttpClient(
-            hs, ip_blacklist=hs.config.federation_ip_range_blacklist
-        )
 
         self.federation_handler = hs.get_handlers().federation_handler
         self.directory_handler = hs.get_handlers().directory_handler
+        self.identity_handler = hs.get_handlers().identity_handler
         self.registration_handler = hs.get_registration_handler()
         self.profile_handler = hs.get_profile_handler()
         self.event_creation_handler = hs.get_event_creation_handler()
@@ -682,7 +668,9 @@ class RoomMemberHandler(object):
                 403, "Looking up third-party identifiers is denied from this server"
             )
 
-        invitee = yield self._lookup_3pid(id_server, medium, address, id_access_token)
+        invitee = yield self.identity_handler.lookup_3pid(
+            id_server, medium, address, id_access_token
+        )
 
         if invitee:
             yield self.update_membership(
@@ -701,211 +689,6 @@ class RoomMemberHandler(object):
             )
 
     @defer.inlineCallbacks
-    def _lookup_3pid(self, id_server, medium, address, id_access_token=None):
-        """Looks up a 3pid in the passed identity server.
-
-        Args:
-            id_server (str): The server name (including port, if required)
-                of the identity server to use.
-            medium (str): The type of the third party identifier (e.g. "email").
-            address (str): The third party identifier (e.g. "foo@example.com").
-            id_access_token (str|None): The access token to authenticate to the identity
-                server with
-
-        Returns:
-            str|None: the matrix ID of the 3pid, or None if it is not recognized.
-        """
-        if id_access_token is not None:
-            try:
-                results = yield self._lookup_3pid_v2(
-                    id_server, id_access_token, medium, address
-                )
-                return results
-
-            except Exception as e:
-                # Catch HttpResponseExcept for a non-200 response code
-                # Check if this identity server does not know about v2 lookups
-                if isinstance(e, HttpResponseException) and e.code == 404:
-                    # This is an old identity server that does not yet support v2 lookups
-                    logger.warning(
-                        "Attempted v2 lookup on v1 identity server %s. Falling "
-                        "back to v1",
-                        id_server,
-                    )
-                else:
-                    logger.warning("Error when looking up hashing details: %s", e)
-                    return None
-
-        return (yield self._lookup_3pid_v1(id_server, medium, address))
-
-    @defer.inlineCallbacks
-    def _lookup_3pid_v1(self, id_server, medium, address):
-        """Looks up a 3pid in the passed identity server using v1 lookup.
-
-        Args:
-            id_server (str): The server name (including port, if required)
-                of the identity server to use.
-            medium (str): The type of the third party identifier (e.g. "email").
-            address (str): The third party identifier (e.g. "foo@example.com").
-
-        Returns:
-            str: the matrix ID of the 3pid, or None if it is not recognized.
-        """
-        try:
-            data = yield self.simple_http_client.get_json(
-                "%s%s/_matrix/identity/api/v1/lookup" % (id_server_scheme, id_server),
-                {"medium": medium, "address": address},
-            )
-
-            if "mxid" in data:
-                if "signatures" not in data:
-                    raise AuthError(401, "No signatures on 3pid binding")
-                yield self._verify_any_signature(data, id_server)
-                return data["mxid"]
-        except TimeoutError:
-            raise SynapseError(500, "Timed out contacting identity server")
-        except IOError as e:
-            logger.warning("Error from v1 identity server lookup: %s" % (e,))
-
-        return None
-
-    @defer.inlineCallbacks
-    def _lookup_3pid_v2(self, id_server, id_access_token, medium, address):
-        """Looks up a 3pid in the passed identity server using v2 lookup.
-
-        Args:
-            id_server (str): The server name (including port, if required)
-                of the identity server to use.
-            id_access_token (str): The access token to authenticate to the identity server with
-            medium (str): The type of the third party identifier (e.g. "email").
-            address (str): The third party identifier (e.g. "foo@example.com").
-
-        Returns:
-            Deferred[str|None]: the matrix ID of the 3pid, or None if it is not recognised.
-        """
-        # Check what hashing details are supported by this identity server
-        try:
-            hash_details = yield self.simple_http_client.get_json(
-                "%s%s/_matrix/identity/v2/hash_details" % (id_server_scheme, id_server),
-                {"access_token": id_access_token},
-            )
-        except TimeoutError:
-            raise SynapseError(500, "Timed out contacting identity server")
-
-        if not isinstance(hash_details, dict):
-            logger.warning(
-                "Got non-dict object when checking hash details of %s%s: %s",
-                id_server_scheme,
-                id_server,
-                hash_details,
-            )
-            raise SynapseError(
-                400,
-                "Non-dict object from %s%s during v2 hash_details request: %s"
-                % (id_server_scheme, id_server, hash_details),
-            )
-
-        # Extract information from hash_details
-        supported_lookup_algorithms = hash_details.get("algorithms")
-        lookup_pepper = hash_details.get("lookup_pepper")
-        if (
-            not supported_lookup_algorithms
-            or not isinstance(supported_lookup_algorithms, list)
-            or not lookup_pepper
-            or not isinstance(lookup_pepper, str)
-        ):
-            raise SynapseError(
-                400,
-                "Invalid hash details received from identity server %s%s: %s"
-                % (id_server_scheme, id_server, hash_details),
-            )
-
-        # Check if any of the supported lookup algorithms are present
-        if LookupAlgorithm.SHA256 in supported_lookup_algorithms:
-            # Perform a hashed lookup
-            lookup_algorithm = LookupAlgorithm.SHA256
-
-            # Hash address, medium and the pepper with sha256
-            to_hash = "%s %s %s" % (address, medium, lookup_pepper)
-            lookup_value = sha256_and_url_safe_base64(to_hash)
-
-        elif LookupAlgorithm.NONE in supported_lookup_algorithms:
-            # Perform a non-hashed lookup
-            lookup_algorithm = LookupAlgorithm.NONE
-
-            # Combine together plaintext address and medium
-            lookup_value = "%s %s" % (address, medium)
-
-        else:
-            logger.warning(
-                "None of the provided lookup algorithms of %s are supported: %s",
-                id_server,
-                supported_lookup_algorithms,
-            )
-            raise SynapseError(
-                400,
-                "Provided identity server does not support any v2 lookup "
-                "algorithms that this homeserver supports.",
-            )
-
-        # Authenticate with identity server given the access token from the client
-        headers = {"Authorization": create_id_access_token_header(id_access_token)}
-
-        try:
-            lookup_results = yield self.simple_http_client.post_json_get_json(
-                "%s%s/_matrix/identity/v2/lookup" % (id_server_scheme, id_server),
-                {
-                    "addresses": [lookup_value],
-                    "algorithm": lookup_algorithm,
-                    "pepper": lookup_pepper,
-                },
-                headers=headers,
-            )
-        except TimeoutError:
-            raise SynapseError(500, "Timed out contacting identity server")
-        except Exception as e:
-            logger.warning("Error when performing a v2 3pid lookup: %s", e)
-            raise SynapseError(
-                500, "Unknown error occurred during identity server lookup"
-            )
-
-        # Check for a mapping from what we looked up to an MXID
-        if "mappings" not in lookup_results or not isinstance(
-            lookup_results["mappings"], dict
-        ):
-            logger.warning("No results from 3pid lookup")
-            return None
-
-        # Return the MXID if it's available, or None otherwise
-        mxid = lookup_results["mappings"].get(lookup_value)
-        return mxid
-
-    @defer.inlineCallbacks
-    def _verify_any_signature(self, data, server_hostname):
-        if server_hostname not in data["signatures"]:
-            raise AuthError(401, "No signature from server %s" % (server_hostname,))
-        for key_name, signature in data["signatures"][server_hostname].items():
-            try:
-                key_data = yield self.simple_http_client.get_json(
-                    "%s%s/_matrix/identity/api/v1/pubkey/%s"
-                    % (id_server_scheme, server_hostname, key_name)
-                )
-            except TimeoutError:
-                raise SynapseError(500, "Timed out contacting identity server")
-            if "public_key" not in key_data:
-                raise AuthError(
-                    401, "No public key named %s from %s" % (key_name, server_hostname)
-                )
-            verify_signed_json(
-                data,
-                server_hostname,
-                decode_verify_key_bytes(
-                    key_name, decode_base64(key_data["public_key"])
-                ),
-            )
-            return
-
-    @defer.inlineCallbacks
     def _make_and_store_3pid_invite(
         self,
         requester,
@@ -951,7 +734,7 @@ class RoomMemberHandler(object):
             room_avatar_url = room_avatar_event.content.get("url", "")
 
         token, public_keys, fallback_public_key, display_name = (
-            yield self._ask_id_server_for_third_party_invite(
+            yield self.identity_handler.ask_id_server_for_third_party_invite(
                 requester=requester,
                 id_server=id_server,
                 medium=medium,
@@ -988,147 +771,6 @@ class RoomMemberHandler(object):
         )
 
     @defer.inlineCallbacks
-    def _ask_id_server_for_third_party_invite(
-        self,
-        requester,
-        id_server,
-        medium,
-        address,
-        room_id,
-        inviter_user_id,
-        room_alias,
-        room_avatar_url,
-        room_join_rules,
-        room_name,
-        inviter_display_name,
-        inviter_avatar_url,
-        id_access_token=None,
-    ):
-        """
-        Asks an identity server for a third party invite.
-
-        Args:
-            requester (Requester)
-            id_server (str): hostname + optional port for the identity server.
-            medium (str): The literal string "email".
-            address (str): The third party address being invited.
-            room_id (str): The ID of the room to which the user is invited.
-            inviter_user_id (str): The user ID of the inviter.
-            room_alias (str): An alias for the room, for cosmetic notifications.
-            room_avatar_url (str): The URL of the room's avatar, for cosmetic
-                notifications.
-            room_join_rules (str): The join rules of the email (e.g. "public").
-            room_name (str): The m.room.name of the room.
-            inviter_display_name (str): The current display name of the
-                inviter.
-            inviter_avatar_url (str): The URL of the inviter's avatar.
-            id_access_token (str|None): The access token to authenticate to the identity
-                server with
-
-        Returns:
-            A deferred tuple containing:
-                token (str): The token which must be signed to prove authenticity.
-                public_keys ([{"public_key": str, "key_validity_url": str}]):
-                    public_key is a base64-encoded ed25519 public key.
-                fallback_public_key: One element from public_keys.
-                display_name (str): A user-friendly name to represent the invited
-                    user.
-        """
-        invite_config = {
-            "medium": medium,
-            "address": address,
-            "room_id": room_id,
-            "room_alias": room_alias,
-            "room_avatar_url": room_avatar_url,
-            "room_join_rules": room_join_rules,
-            "room_name": room_name,
-            "sender": inviter_user_id,
-            "sender_display_name": inviter_display_name,
-            "sender_avatar_url": inviter_avatar_url,
-        }
-
-        # Add the identity service access token to the JSON body and use the v2
-        # Identity Service endpoints if id_access_token is present
-        data = None
-        base_url = "%s%s/_matrix/identity" % (id_server_scheme, id_server)
-
-        if id_access_token:
-            key_validity_url = "%s%s/_matrix/identity/v2/pubkey/isvalid" % (
-                id_server_scheme,
-                id_server,
-            )
-
-            # Attempt a v2 lookup
-            url = base_url + "/v2/store-invite"
-            try:
-                data = yield self.simple_http_client.post_json_get_json(
-                    url,
-                    invite_config,
-                    {"Authorization": create_id_access_token_header(id_access_token)},
-                )
-            except TimeoutError:
-                raise SynapseError(500, "Timed out contacting identity server")
-            except HttpResponseException as e:
-                if e.code != 404:
-                    logger.info("Failed to POST %s with JSON: %s", url, e)
-                    raise e
-
-        if data is None:
-            key_validity_url = "%s%s/_matrix/identity/api/v1/pubkey/isvalid" % (
-                id_server_scheme,
-                id_server,
-            )
-            url = base_url + "/api/v1/store-invite"
-
-            try:
-                data = yield self.simple_http_client.post_json_get_json(
-                    url, invite_config
-                )
-            except TimeoutError:
-                raise SynapseError(500, "Timed out contacting identity server")
-            except HttpResponseException as e:
-                logger.warning(
-                    "Error trying to call /store-invite on %s%s: %s",
-                    id_server_scheme,
-                    id_server,
-                    e,
-                )
-
-            if data is None:
-                # Some identity servers may only support application/x-www-form-urlencoded
-                # types. This is especially true with old instances of Sydent, see
-                # https://github.com/matrix-org/sydent/pull/170
-                try:
-                    data = yield self.simple_http_client.post_urlencoded_get_json(
-                        url, invite_config
-                    )
-                except HttpResponseException as e:
-                    logger.warning(
-                        "Error calling /store-invite on %s%s with fallback "
-                        "encoding: %s",
-                        id_server_scheme,
-                        id_server,
-                        e,
-                    )
-                    raise e
-
-        # TODO: Check for success
-        token = data["token"]
-        public_keys = data.get("public_keys", [])
-        if "public_key" in data:
-            fallback_public_key = {
-                "public_key": data["public_key"],
-                "key_validity_url": key_validity_url,
-            }
-        else:
-            fallback_public_key = public_keys[0]
-
-        if not public_keys:
-            public_keys.append(fallback_public_key)
-        display_name = data["display_name"]
-        return token, public_keys, fallback_public_key, display_name
-
-    @defer.inlineCallbacks
     def _is_host_in_room(self, current_state_ids):
         # Have we just created the room, and is this about to be the very
         # first member event?