Use the v2 lookup API for 3PID invites

changelog.d/5897.feature

@@ -0,0 +1 @@
+Switch to the v2 lookup API for 3PID invites.

synapse/handlers/identity.py

@@ -18,6 +18,7 @@
 """Utilities for interacting with Identity Servers"""
 
 import logging
+from enum import Enum
 
 from canonicaljson import json
 
@@ -282,3 +283,16 @@ def requestMsisdnToken(
         except HttpResponseException as e:
             logger.info("Proxied requestToken failed: %r", e)
             raise e.to_synapse_error()
+
+
+class LookupAlgorithm(Enum):
+    """
+    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"

synapse/handlers/room_member.py

@@ -29,9 +29,11 @@
 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
 
@@ -697,6 +699,37 @@ def _lookup_3pid(self, id_server, medium, address):
             raise SynapseError(
                 403, "Looking up third-party identifiers is denied from this server"
             )
+
+        # 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)
+            )
+        except (HttpResponseException, ValueError) as e:
+            # Check if this identity server does not know about v2 lookups
+            if HttpResponseException.code == 404:
+                # This is an old identity server that does not yet support v2 lookups
+                return self._lookup_3pid_v1(id_server, medium, address)
+
+            logger.warn("Error when looking up hashing details: %s" % (e,))
+            return None
+
+        res = yield self._lookup_3pid_v2(id_server, medium, address, hash_details)
+        return res
+
+    @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),
@@ -711,8 +744,78 @@ def _lookup_3pid(self, id_server, medium, address):
 
         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]): A dictionary containing hashing information
+                provided by an identity server.
+
+        Returns:
+            str: the matrix ID of the 3pid, or None if it is not recognized.
+        """
+        # Extract information from hash_details
+        supported_lookup_algorithms = hash_details["algorithms"]
+        lookup_pepper = hash_details["lookup_pepper"]
+
+        # Check if none of the supported lookup algorithms are present
+        if not any(
+            i in supported_lookup_algorithms
+            for i in [LookupAlgorithm.SHA256, LookupAlgorithm.NONE]
+        ):
+            logger.warn(
+                "No supported lookup algorithms found for %s%s"
+                % (id_server_scheme, id_server)
+            )
+
             return None
 
+        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)
+
+        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:
+            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
+        return lookup_results["mappings"].get(lookup_value)
+
     @defer.inlineCallbacks
     def _verify_any_signature(self, data, server_hostname):
         if server_hostname not in data["signatures"]:

synapse/util/hash.py

@@ -0,0 +1,33 @@
+# -*- 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)