Use the v2 Identity Service API for lookups (MSC2134 + MSC2140)

changelog.d/5897.feature

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

synapse/handlers/identity.py

@@ -20,15 +20,20 @@
 import logging
 
 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 synapse.api.errors import (
+    AuthError,
     CodeMessageException,
     Codes,
     HttpResponseException,
     SynapseError,
 )
+from synapse.util.hash import sha256_and_url_safe_base64
 
 from ._base import BaseHandler
 
@@ -282,3 +287,192 @@ def requestMsisdnToken(
         except HttpResponseException as e:
             logger.info("Proxied requestToken failed: %r", e)
             raise e.to_synapse_error()
+
+    @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 protocol and 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. "[email protected]").
+            id_access_token (str|None): The access token to authenticate to the identity
+                server with
+
+        Returns:
+            str: the matrix ID of the 3pid, or None if it is not recognized.
+        """
+        # If an access token is present, add it to the query params of the hash_details request
+        query_params = {}
+        if id_access_token is not None:
+            query_params["id_access_token"] = id_access_token
+
+        # Check what hashing details are supported by this identity server
+        use_v1 = False
+        hash_details = None
+        try:
+            hash_details = yield self.http_client.get_json(
+                "%s/_matrix/identity/v2/hash_details" % id_server, query_params
+            )
+        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, id_access_token, 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 protocol and 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. "[email protected]").
+
+        Returns:
+            str: the matrix ID of the 3pid, or None if it is not recognized.
+        """
+        try:
+            data = yield self.http_client.get_json(
+                "%s/_matrix/identity/api/v1/lookup" % (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 IOError as e:
+            logger.warn("Error from identity server lookup: %s" % (e,))
+
+        return None
+
+    @defer.inlineCallbacks
+    def _lookup_3pid_v2(
+        self, id_server, id_access_token, medium, address, hash_details
+    ):
+        """Looks up a 3pid in the passed identity server using v2 lookup.
+
+        Args:
+            id_server (str): The server name (including protocol and 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. "[email protected]").
+            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 are supported: %s",
+                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.http_client.post_json_get_json(
+                "%s/_matrix/identity/v2/lookup" % id_server,
+                {
+                    "id_access_token": id_access_token,
+                    "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"]:
+            raise AuthError(401, "No signature from server %s" % (server_hostname,))
+        for key_name, signature in data["signatures"][server_hostname].items():
+            key_data = yield self.http_client.get_json(
+                "%s/_matrix/identity/api/v1/pubkey/%s" % (server_hostname, key_name)
+            )
+            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
+
+
+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"

synapse/handlers/room.py

@@ -579,8 +579,8 @@ def create_room(self, requester, config, ratelimit=True, creator_join_profile=No
 
         room_id = yield self._generate_room_id(creator_id=user_id, is_public=is_public)
 
+        directory_handler = self.hs.get_handlers().directory_handler
         if room_alias:
-            directory_handler = self.hs.get_handlers().directory_handler
             yield directory_handler.create_association(
                 requester=requester,
                 room_id=room_id,
@@ -665,6 +665,7 @@ def create_room(self, requester, config, ratelimit=True, creator_join_profile=No
 
         for invite_3pid in invite_3pid_list:
             id_server = invite_3pid["id_server"]
+            id_access_token = invite_3pid.get("id_access_token")  # optional
             address = invite_3pid["address"]
             medium = invite_3pid["medium"]
             yield self.hs.get_room_member_handler().do_3pid_invite(
@@ -675,6 +676,7 @@ def create_room(self, requester, config, ratelimit=True, creator_join_profile=No
                 id_server,
                 requester,
                 txn_id=None,
+                id_access_token=id_access_token,
             )
 
         result = {"room_id": room_id}