Implement remote key lookup api

synapse/rest/key/v2/remote_key_resource.py

@@ -0,0 +1,174 @@
+from synapse.http.server import request_handler, respond_with_json_bytes
+from synapse.api.errors import SynapseError, Codes
+
+from twisted.web.resource import Resource
+from twisted.web.server import NOT_DONE_YET
+from twisted.internet import defer
+
+
+from io import BytesIO
+import json
+import logging
+logger = logging.getLogger(__name__)
+
+
+class RemoteKey(Resource):
+    """HTTP resource for retreiving the TLS certificate and NACL signature
+    verification keys for a collection of servers. Checks that the reported
+    X.509 TLS certificate matches the one used in the HTTPS connection. Checks
+    that the NACL signature for the remote server is valid. Returns a dict of
+    JSON signed by both the remote server and by this server.
+
+    Supports individual GET APIs and a bulk query POST API.
+
+    Requsts:
+
+    GET /_matrix/key/v2/query/remote.server.example.com HTTP/1.1
+
+    GET /_matrix/key/v2/query/remote.server.example.com/a.key.id HTTP/1.1
+
+    POST /_matrix/v2/query HTTP/1.1
+    Content-Type: application/json
+    {
+        "server_keys": { "remote.server.example.com": ["a.key.id"] }
+    }
+
+    Response:
+
+    HTTP/1.1 200 OK
+    Content-Type: application/json
+    {
+        "server_keys": [
+            {
+                "server_name": "remote.server.example.com"
+                "valid_until": # posix timestamp
+                "verify_keys": {
+                    "a.key.id": { # The identifier for a key.
+                        key: "" # base64 encoded verification key.
+                    }
+                }
+                "old_verify_keys": {
+                    "an.old.key.id": { # The identifier for an old key.
+                        key: "", # base64 encoded key
+                        expired: 0, # when th e
+                    }
+                }
+                "tls_fingerprints": [
+                    { "sha256": # fingerprint }
+                ]
+                "signatures": {
+                    "remote.server.example.com": {...}
+                    "this.server.example.com": {...}
+                }
+            }
+        ]
+    }
+    """
+
+    isLeaf = True
+
+    def __init__(self, hs):
+        self.keyring = hs.get_keyring()
+        self.store = hs.get_datastore()
+        self.version_string = hs.version_string
+        self.clock = hs.get_clock()
+
+    def render_GET(self, request):
+        self.async_render_GET(request)
+        return NOT_DONE_YET
+
+    @request_handler
+    @defer.inlineCallbacks
+    def async_render_GET(self, request):
+        if len(request.postpath) == 1:
+            server, = request.postpath
+            query = {server: [None]}
+        elif len(request.postpath) == 2:
+            server, key_id = request.postpath
+            query = {server: [key_id]}
+        else:
+            raise SynapseError(
+                404, "Not found %r" % request.postpath, Codes.NOT_FOUND
+            )
+        yield self.query_keys(request, query, query_remote_on_cache_miss=True)
+
+    def render_POST(self, request):
+        self.async_render_POST(request)
+        return NOT_DONE_YET
+
+    @request_handler
+    @defer.inlineCallbacks
+    def async_render_POST(self, request):
+        try:
+            content = json.loads(request.content.read())
+            if type(content) != dict:
+                raise ValueError()
+        except ValueError:
+            raise SynapseError(
+                400, "Content must be JSON object.", errcode=Codes.NOT_JSON
+            )
+
+        query = content["server_keys"]
+
+        yield self.query_keys(request, query, query_remote_on_cache_miss=True)
+
+    @defer.inlineCallbacks
+    def query_keys(self, request, query, query_remote_on_cache_miss=False):
+        store_queries = []
+        for server_name, key_ids in query.items():
+            for key_id in key_ids:
+                store_queries.append((server_name, key_id, None))
+
+        cached = yield self.store.get_server_keys_json(store_queries)
+
+        json_results = []
+
+        time_now_ms = self.clock.time_msec()
+
+        cache_misses = dict()
+        for (server_name, key_id, from_server), results in cached.items():
+            results = [
+                (result["ts_added_ms"], result) for result in results
+                if result["ts_valid_until_ms"] > time_now_ms
+            ]
+
+            if not results:
+                if key_id is not None:
+                    cache_misses.setdefault(server_name, set()).add(key_id)
+                continue
+
+            if key_id is not None:
+                most_recent_result = max(results)
+                json_results.append(most_recent_result[-1]["key_json"])
+            else:
+                for result in results:
+                    json_results.append(result[-1]["key_json"])
+
+        if cache_misses and query_remote_on_cache_miss:
+            for server_name, key_ids in cache_misses.items():
+                try:
+                    yield self.keyring.get_server_verify_key_v2_direct(
+                        server_name, key_ids
+                    )
+                except:
+                    logger.exception("Failed to get key for %r", server_name)
+                    pass
+            yield self.query_keys(
+                request, query, query_remote_on_cache_miss=False
+            )
+        else:
+            result_io = BytesIO()
+            result_io.write(b"{\"server_keys\":")
+            sep = b"["
+            for json_bytes in json_results:
+                result_io.write(sep)
+                result_io.write(json_bytes)
+                sep = b","
+            if sep == b"[":
+                result_io.write(sep)
+            result_io.write(b"]}")
+
+            respond_with_json_bytes(
+                request, 200, result_io.getvalue(),
+                version_string=self.version_string
+            )