Revert "Use the v2 lookup API for 3PID invites (#5897)" (#5937)

This reverts commit 71fc04069a5770a204c3514e0237d7374df257a8.

This broke 3PID invites as #5892 was required for it to work correctly.

4 files changed, 9 insertions, 166 deletions

diff --git a/changelog.d/5897.feature b/changelog.d/5897.feature
deleted file mode 100644
index 7b10774c96..0000000000
--- a/changelog.d/5897.feature
+++ /dev/null
@@ -1 +0,0 @@
-Switch to the v2 lookup API for 3PID invites.
\ No newline at end of file
diff --git a/synapse/handlers/identity.py b/synapse/handlers/identity.py
index 97daca5fee..d199521b58 100644
--- a/synapse/handlers/identity.py
+++ b/synapse/handlers/identity.py
@@ -282,16 +282,3 @@ class IdentityHandler(BaseHandler):
         except HttpResponseException as e:
             logger.info("Proxied requestToken failed: %r", e)
             raise e.to_synapse_error()
-
-
-class LookupAlgorithm:
-    """
-    Supported hashing algorithms when performing a 3PID lookup.
-
-    SHA256 - Hashing an (address, medium, pepper) combo with sha256, then url-safe base64
-        encoding
-    NONE - Not performing any hashing. Simply sending an (address, medium) combo in plaintext
-    """
-
-    SHA256 = "sha256"
-    NONE = "none"
diff --git a/synapse/handlers/room_member.py b/synapse/handlers/room_member.py
index 4605cb9c0b..249a6d9c5d 100644
--- a/synapse/handlers/room_member.py
+++ b/synapse/handlers/room_member.py
@@ -29,11 +29,9 @@ from twisted.internet import defer
 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
 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
 
@@ -525,7 +523,7 @@ class RoomMemberHandler(object):
             event (SynapseEvent): The membership event.
             context: The context of the event.
             is_guest (bool): Whether the sender is a guest.
-            remote_room_hosts (list[str]|None): Homeservers which are likely to already be in
+            room_hosts ([str]): Homeservers which are likely to already be in
                 the room, and could be danced with in order to join this
                 homeserver for the first time.
             ratelimit (bool): Whether to rate limit this request.
@@ -636,7 +634,7 @@ class RoomMemberHandler(object):
             servers.remove(room_alias.domain)
         servers.insert(0, room_alias.domain)
 
-        return RoomID.from_string(room_id), servers
+        return (RoomID.from_string(room_id), servers)
 
     @defer.inlineCallbacks
     def _get_inviter(self, user_id, room_id):
@@ -699,44 +697,6 @@ class RoomMemberHandler(object):
             raise SynapseError(
                 403, "Looking up third-party identifiers is denied from this server"
             )
-
-        # Check what hashing details are supported by this identity server
-        use_v1 = False
-        hash_details = None
-        try:
-            hash_details = yield self.simple_http_client.get_json(
-                "%s%s/_matrix/identity/v2/hash_details" % (id_server_scheme, id_server)
-            )
-        except (HttpResponseException, ValueError) as e:
-            # Catch HttpResponseExcept for a non-200 response code
-            # Catch ValueError for non-JSON response body
-
-            # Check if this identity server does not know about v2 lookups
-            if e.code == 404:
-                # This is an old identity server that does not yet support v2 lookups
-                use_v1 = True
-            else:
-                logger.warn("Error when looking up hashing details: %s" % (e,))
-                return None
-
-        if use_v1:
-            return (yield self._lookup_3pid_v1(id_server, medium, address))
-
-        return (yield self._lookup_3pid_v2(id_server, medium, address, hash_details))
-
-    @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),
@@ -751,83 +711,8 @@ class RoomMemberHandler(object):
 
         except IOError as e:
             logger.warn("Error from identity server lookup: %s" % (e,))
-
-        return None
-
-    @defer.inlineCallbacks
-    def _lookup_3pid_v2(self, id_server, medium, address, hash_details):
-        """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.
-            medium (str): The type of the third party identifier (e.g. "email").
-            address (str): The third party identifier (e.g. "foo@example.com").
-            hash_details (dict[str, str|list]): A dictionary containing hashing information
-                provided by an identity server.
-
-        Returns:
-            Deferred[str|None]: the matrix ID of the 3pid, or None if it is not recognised.
-        """
-        # Extract information from hash_details
-        supported_lookup_algorithms = hash_details["algorithms"]
-        lookup_pepper = hash_details["lookup_pepper"]
-
-        # 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.warn(
-                "None of the provided lookup algorithms of %s%s are supported: %s",
-                id_server_scheme,
-                id_server,
-                hash_details["algorithms"],
-            )
-            raise SynapseError(
-                400,
-                "Provided identity server does not support any v2 lookup "
-                "algorithms that this homeserver supports.",
-            )
-
-        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,
-                },
-            )
-        except (HttpResponseException, ValueError) as e:
-            # Catch HttpResponseExcept for a non-200 response code
-            # Catch ValueError for non-JSON response body
-            logger.warn("Error when performing a 3pid lookup: %s" % (e,))
-            return None
-
-        # 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.debug("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"]:
@@ -1077,7 +962,9 @@ class RoomMemberMasterHandler(RoomMemberHandler):
         )
 
         if complexity:
-            return complexity["v1"] > max_complexity
+            if complexity["v1"] > max_complexity:
+                return True
+            return False
         return None
 
     @defer.inlineCallbacks
@@ -1093,7 +980,10 @@ class RoomMemberMasterHandler(RoomMemberHandler):
         max_complexity = self.hs.config.limit_remote_rooms.complexity
         complexity = yield self.store.get_room_complexity(room_id)
 
-        return complexity["v1"] > max_complexity
+        if complexity["v1"] > max_complexity:
+            return True
+
+        return False
 
     @defer.inlineCallbacks
     def _remote_join(self, requester, remote_room_hosts, room_id, user, content):
diff --git a/synapse/util/hash.py b/synapse/util/hash.py
deleted file mode 100644
index 359168704e..0000000000
--- a/synapse/util/hash.py
+++ /dev/null
@@ -1,33 +0,0 @@
-# -*- coding: utf-8 -*-
-
-# Copyright 2019 The Matrix.org Foundation C.I.C.
-#
-# 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.
-
-import hashlib
-
-import unpaddedbase64
-
-
-def sha256_and_url_safe_base64(input_text):
-    """SHA256 hash an input string, encode the digest as url-safe base64, and
-    return
-
-    :param input_text: string to hash
-    :type input_text: str
-
-    :returns a sha256 hashed and url-safe base64 encoded digest
-    :rtype: str
-    """
-    digest = hashlib.sha256(input_text.encode()).digest()
-    return unpaddedbase64.encode_base64(digest, urlsafe=True)