Port rest/ to Python 3 (#3823)

17 files changed, 112 insertions, 100 deletions

diff --git a/synapse/rest/client/v1/admin.py b/synapse/rest/client/v1/admin.py
index ad536ab570..41534b8c2a 100644
--- a/synapse/rest/client/v1/admin.py
+++ b/synapse/rest/client/v1/admin.py
@@ -101,7 +101,7 @@ class UserRegisterServlet(ClientV1RestServlet):
 
         nonce = self.hs.get_secrets().token_hex(64)
         self.nonces[nonce] = int(self.reactor.seconds())
-        return (200, {"nonce": nonce.encode('ascii')})
+        return (200, {"nonce": nonce})
 
     @defer.inlineCallbacks
     def on_POST(self, request):
@@ -164,7 +164,7 @@ class UserRegisterServlet(ClientV1RestServlet):
             key=self.hs.config.registration_shared_secret.encode(),
             digestmod=hashlib.sha1,
         )
-        want_mac.update(nonce)
+        want_mac.update(nonce.encode('utf8'))
         want_mac.update(b"\x00")
         want_mac.update(username)
         want_mac.update(b"\x00")
@@ -173,7 +173,10 @@ class UserRegisterServlet(ClientV1RestServlet):
         want_mac.update(b"admin" if admin else b"notadmin")
         want_mac = want_mac.hexdigest()
 
-        if not hmac.compare_digest(want_mac, got_mac.encode('ascii')):
+        if not hmac.compare_digest(
+                want_mac.encode('ascii'),
+                got_mac.encode('ascii')
+        ):
             raise SynapseError(403, "HMAC incorrect")
 
         # Reuse the parts of RegisterRestServlet to reduce code duplication
diff --git a/synapse/rest/client/v1/events.py b/synapse/rest/client/v1/events.py
index 0f3a2e8b51..cd9b3bdbd1 100644
--- a/synapse/rest/client/v1/events.py
+++ b/synapse/rest/client/v1/events.py
@@ -45,20 +45,20 @@ class EventStreamRestServlet(ClientV1RestServlet):
         is_guest = requester.is_guest
         room_id = None
         if is_guest:
-            if "room_id" not in request.args:
+            if b"room_id" not in request.args:
                 raise SynapseError(400, "Guest users must specify room_id param")
-        if "room_id" in request.args:
-            room_id = request.args["room_id"][0]
+        if b"room_id" in request.args:
+            room_id = request.args[b"room_id"][0].decode('ascii')
 
         pagin_config = PaginationConfig.from_request(request)
         timeout = EventStreamRestServlet.DEFAULT_LONGPOLL_TIME_MS
-        if "timeout" in request.args:
+        if b"timeout" in request.args:
             try:
-                timeout = int(request.args["timeout"][0])
+                timeout = int(request.args[b"timeout"][0])
             except ValueError:
                 raise SynapseError(400, "timeout must be in milliseconds.")
 
-        as_client_event = "raw" not in request.args
+        as_client_event = b"raw" not in request.args
 
         chunk = yield self.event_stream_handler.get_stream(
             requester.user.to_string(),
diff --git a/synapse/rest/client/v1/initial_sync.py b/synapse/rest/client/v1/initial_sync.py
index fd5f85b53e..3ead75cb77 100644
--- a/synapse/rest/client/v1/initial_sync.py
+++ b/synapse/rest/client/v1/initial_sync.py
@@ -32,7 +32,7 @@ class InitialSyncRestServlet(ClientV1RestServlet):
     @defer.inlineCallbacks
     def on_GET(self, request):
         requester = yield self.auth.get_user_by_req(request)
-        as_client_event = "raw" not in request.args
+        as_client_event = b"raw" not in request.args
         pagination_config = PaginationConfig.from_request(request)
         include_archived = parse_boolean(request, "archived", default=False)
         content = yield self.initial_sync_handler.snapshot_all_rooms(
diff --git a/synapse/rest/client/v1/login.py b/synapse/rest/client/v1/login.py
index cb85fa1436..0010699d31 100644
--- a/synapse/rest/client/v1/login.py
+++ b/synapse/rest/client/v1/login.py
@@ -14,10 +14,9 @@
 # limitations under the License.
 
 import logging
-import urllib
 import xml.etree.ElementTree as ET
 
-from six.moves.urllib import parse as urlparse
+from six.moves import urllib
 
 from canonicaljson import json
 from saml2 import BINDING_HTTP_POST, config
@@ -134,7 +133,7 @@ class LoginRestServlet(ClientV1RestServlet):
                                        LoginRestServlet.SAML2_TYPE):
                 relay_state = ""
                 if "relay_state" in login_submission:
-                    relay_state = "&RelayState=" + urllib.quote(
+                    relay_state = "&RelayState=" + urllib.parse.quote(
                                   login_submission["relay_state"])
                 result = {
                     "uri": "%s%s" % (self.idp_redirect_url, relay_state)
@@ -366,7 +365,7 @@ class SAML2RestServlet(ClientV1RestServlet):
             (user_id, token) = yield handler.register_saml2(username)
             # Forward to the RelayState callback along with ava
             if 'RelayState' in request.args:
-                request.redirect(urllib.unquote(
+                request.redirect(urllib.parse.unquote(
                                  request.args['RelayState'][0]) +
                                  '?status=authenticated&access_token=' +
                                  token + '&user_id=' + user_id + '&ava=' +
@@ -377,7 +376,7 @@ class SAML2RestServlet(ClientV1RestServlet):
                                      "user_id": user_id, "token": token,
                                      "ava": saml2_auth.ava}))
         elif 'RelayState' in request.args:
-            request.redirect(urllib.unquote(
+            request.redirect(urllib.parse.unquote(
                              request.args['RelayState'][0]) +
                              '?status=not_authenticated')
             finish_request(request)
@@ -390,21 +389,22 @@ class CasRedirectServlet(ClientV1RestServlet):
 
     def __init__(self, hs):
         super(CasRedirectServlet, self).__init__(hs)
-        self.cas_server_url = hs.config.cas_server_url
-        self.cas_service_url = hs.config.cas_service_url
+        self.cas_server_url = hs.config.cas_server_url.encode('ascii')
+        self.cas_service_url = hs.config.cas_service_url.encode('ascii')
 
     def on_GET(self, request):
         args = request.args
-        if "redirectUrl" not in args:
+        if b"redirectUrl" not in args:
             return (400, "Redirect URL not specified for CAS auth")
-        client_redirect_url_param = urllib.urlencode({
-            "redirectUrl": args["redirectUrl"][0]
-        })
-        hs_redirect_url = self.cas_service_url + "/_matrix/client/api/v1/login/cas/ticket"
-        service_param = urllib.urlencode({
-            "service": "%s?%s" % (hs_redirect_url, client_redirect_url_param)
-        })
-        request.redirect("%s/login?%s" % (self.cas_server_url, service_param))
+        client_redirect_url_param = urllib.parse.urlencode({
+            b"redirectUrl": args[b"redirectUrl"][0]
+        }).encode('ascii')
+        hs_redirect_url = (self.cas_service_url +
+                           b"/_matrix/client/api/v1/login/cas/ticket")
+        service_param = urllib.parse.urlencode({
+            b"service": b"%s?%s" % (hs_redirect_url, client_redirect_url_param)
+        }).encode('ascii')
+        request.redirect(b"%s/login?%s" % (self.cas_server_url, service_param))
         finish_request(request)
 
 
@@ -422,11 +422,11 @@ class CasTicketServlet(ClientV1RestServlet):
 
     @defer.inlineCallbacks
     def on_GET(self, request):
-        client_redirect_url = request.args["redirectUrl"][0]
+        client_redirect_url = request.args[b"redirectUrl"][0]
         http_client = self.hs.get_simple_http_client()
         uri = self.cas_server_url + "/proxyValidate"
         args = {
-            "ticket": request.args["ticket"],
+            "ticket": request.args[b"ticket"][0].decode('ascii'),
             "service": self.cas_service_url
         }
         try:
@@ -471,11 +471,11 @@ class CasTicketServlet(ClientV1RestServlet):
         finish_request(request)
 
     def add_login_token_to_redirect_url(self, url, token):
-        url_parts = list(urlparse.urlparse(url))
-        query = dict(urlparse.parse_qsl(url_parts[4]))
+        url_parts = list(urllib.parse.urlparse(url))
+        query = dict(urllib.parse.parse_qsl(url_parts[4]))
         query.update({"loginToken": token})
-        url_parts[4] = urllib.urlencode(query)
-        return urlparse.urlunparse(url_parts)
+        url_parts[4] = urllib.parse.urlencode(query).encode('ascii')
+        return urllib.parse.urlunparse(url_parts)
 
     def parse_cas_response(self, cas_response_body):
         user = None
diff --git a/synapse/rest/client/v1/push_rule.py b/synapse/rest/client/v1/push_rule.py
index 6e95d9bec2..9382b1f124 100644
--- a/synapse/rest/client/v1/push_rule.py
+++ b/synapse/rest/client/v1/push_rule.py
@@ -46,7 +46,7 @@ class PushRuleRestServlet(ClientV1RestServlet):
         try:
             priority_class = _priority_class_from_spec(spec)
         except InvalidRuleException as e:
-            raise SynapseError(400, e.message)
+            raise SynapseError(400, str(e))
 
         requester = yield self.auth.get_user_by_req(request)
 
@@ -73,7 +73,7 @@ class PushRuleRestServlet(ClientV1RestServlet):
                 content,
             )
         except InvalidRuleException as e:
-            raise SynapseError(400, e.message)
+            raise SynapseError(400, str(e))
 
         before = parse_string(request, "before")
         if before:
@@ -95,9 +95,9 @@ class PushRuleRestServlet(ClientV1RestServlet):
             )
             self.notify_user(user_id)
         except InconsistentRuleException as e:
-            raise SynapseError(400, e.message)
+            raise SynapseError(400, str(e))
         except RuleNotFoundException as e:
-            raise SynapseError(400, e.message)
+            raise SynapseError(400, str(e))
 
         defer.returnValue((200, {}))
 
@@ -142,10 +142,10 @@ class PushRuleRestServlet(ClientV1RestServlet):
                 PushRuleRestServlet.SLIGHTLY_PEDANTIC_TRAILING_SLASH_ERROR
             )
 
-        if path[0] == '':
+        if path[0] == b'':
             defer.returnValue((200, rules))
-        elif path[0] == 'global':
-            path = path[1:]
+        elif path[0] == b'global':
+            path = [x.decode('ascii') for x in path[1:]]
             result = _filter_ruleset_with_path(rules['global'], path)
             defer.returnValue((200, result))
         else:
@@ -192,10 +192,10 @@ class PushRuleRestServlet(ClientV1RestServlet):
 def _rule_spec_from_path(path):
     if len(path) < 2:
         raise UnrecognizedRequestError()
-    if path[0] != 'pushrules':
+    if path[0] != b'pushrules':
         raise UnrecognizedRequestError()
 
-    scope = path[1]
+    scope = path[1].decode('ascii')
     path = path[2:]
     if scope != 'global':
         raise UnrecognizedRequestError()
@@ -203,13 +203,13 @@ def _rule_spec_from_path(path):
     if len(path) == 0:
         raise UnrecognizedRequestError()
 
-    template = path[0]
+    template = path[0].decode('ascii')
     path = path[1:]
 
     if len(path) == 0 or len(path[0]) == 0:
         raise UnrecognizedRequestError()
 
-    rule_id = path[0]
+    rule_id = path[0].decode('ascii')
 
     spec = {
         'scope': scope,
@@ -220,7 +220,7 @@ def _rule_spec_from_path(path):
     path = path[1:]
 
     if len(path) > 0 and len(path[0]) > 0:
-        spec['attr'] = path[0]
+        spec['attr'] = path[0].decode('ascii')
 
     return spec
 
diff --git a/synapse/rest/client/v1/pusher.py b/synapse/rest/client/v1/pusher.py
index 182a68b1e2..b84f0260f2 100644
--- a/synapse/rest/client/v1/pusher.py
+++ b/synapse/rest/client/v1/pusher.py
@@ -59,7 +59,7 @@ class PushersRestServlet(ClientV1RestServlet):
         ]
 
         for p in pushers:
-            for k, v in p.items():
+            for k, v in list(p.items()):
                 if k not in allowed_keys:
                     del p[k]
 
@@ -126,7 +126,7 @@ class PushersSetRestServlet(ClientV1RestServlet):
                 profile_tag=content.get('profile_tag', ""),
             )
         except PusherConfigException as pce:
-            raise SynapseError(400, "Config Error: " + pce.message,
+            raise SynapseError(400, "Config Error: " + str(pce),
                                errcode=Codes.MISSING_PARAM)
 
         self.notifier.on_new_replication_data()
diff --git a/synapse/rest/client/v1/room.py b/synapse/rest/client/v1/room.py
index 976d98387d..663934efd0 100644
--- a/synapse/rest/client/v1/room.py
+++ b/synapse/rest/client/v1/room.py
@@ -207,7 +207,7 @@ class RoomSendEventRestServlet(ClientV1RestServlet):
             "sender": requester.user.to_string(),
         }
 
-        if 'ts' in request.args and requester.app_service:
+        if b'ts' in request.args and requester.app_service:
             event_dict['origin_server_ts'] = parse_integer(request, "ts", 0)
 
         event = yield self.event_creation_hander.create_and_send_nonmember_event(
@@ -255,7 +255,9 @@ class JoinRoomAliasServlet(ClientV1RestServlet):
         if RoomID.is_valid(room_identifier):
             room_id = room_identifier
             try:
-                remote_room_hosts = request.args["server_name"]
+                remote_room_hosts = [
+                    x.decode('ascii') for x in request.args[b"server_name"]
+                ]
             except Exception:
                 remote_room_hosts = None
         elif RoomAlias.is_valid(room_identifier):
@@ -461,10 +463,10 @@ class RoomMessageListRestServlet(ClientV1RestServlet):
         pagination_config = PaginationConfig.from_request(
             request, default_limit=10,
         )
-        as_client_event = "raw" not in request.args
-        filter_bytes = parse_string(request, "filter")
+        as_client_event = b"raw" not in request.args
+        filter_bytes = parse_string(request, b"filter", encoding=None)
         if filter_bytes:
-            filter_json = urlparse.unquote(filter_bytes).decode("UTF-8")
+            filter_json = urlparse.unquote(filter_bytes.decode("UTF-8"))
             event_filter = Filter(json.loads(filter_json))
         else:
             event_filter = None
@@ -560,7 +562,7 @@ class RoomEventContextServlet(ClientV1RestServlet):
         # picking the API shape for symmetry with /messages
         filter_bytes = parse_string(request, "filter")
         if filter_bytes:
-            filter_json = urlparse.unquote(filter_bytes).decode("UTF-8")
+            filter_json = urlparse.unquote(filter_bytes)
             event_filter = Filter(json.loads(filter_json))
         else:
             event_filter = None
diff --git a/synapse/rest/client/v2_alpha/sync.py b/synapse/rest/client/v2_alpha/sync.py
index 263d8eb73e..0251146722 100644
--- a/synapse/rest/client/v2_alpha/sync.py
+++ b/synapse/rest/client/v2_alpha/sync.py
@@ -89,7 +89,7 @@ class SyncRestServlet(RestServlet):
 
     @defer.inlineCallbacks
     def on_GET(self, request):
-        if "from" in request.args:
+        if b"from" in request.args:
             # /events used to use 'from', but /sync uses 'since'.
             # Lets be helpful and whine if we see a 'from'.
             raise SynapseError(
diff --git a/synapse/rest/client/v2_alpha/thirdparty.py b/synapse/rest/client/v2_alpha/thirdparty.py
index d9d379182e..b9b5d07677 100644
--- a/synapse/rest/client/v2_alpha/thirdparty.py
+++ b/synapse/rest/client/v2_alpha/thirdparty.py
@@ -79,7 +79,7 @@ class ThirdPartyUserServlet(RestServlet):
         yield self.auth.get_user_by_req(request, allow_guest=True)
 
         fields = request.args
-        fields.pop("access_token", None)
+        fields.pop(b"access_token", None)
 
         results = yield self.appservice_handler.query_3pe(
             ThirdPartyEntityKind.USER, protocol, fields
@@ -102,7 +102,7 @@ class ThirdPartyLocationServlet(RestServlet):
         yield self.auth.get_user_by_req(request, allow_guest=True)
 
         fields = request.args
-        fields.pop("access_token", None)
+        fields.pop(b"access_token", None)
 
         results = yield self.appservice_handler.query_3pe(
             ThirdPartyEntityKind.LOCATION, protocol, fields
diff --git a/synapse/rest/key/v1/server_key_resource.py b/synapse/rest/key/v1/server_key_resource.py
index b9ee6e1c13..38eb2ee23f 100644
--- a/synapse/rest/key/v1/server_key_resource.py
+++ b/synapse/rest/key/v1/server_key_resource.py
@@ -88,5 +88,5 @@ class LocalKey(Resource):
         )
 
     def getChild(self, name, request):
-        if name == '':
+        if name == b'':
             return self
diff --git a/synapse/rest/key/v2/__init__.py b/synapse/rest/key/v2/__init__.py
index 3491fd2118..cb5abcf826 100644
--- a/synapse/rest/key/v2/__init__.py
+++ b/synapse/rest/key/v2/__init__.py
@@ -22,5 +22,5 @@ from .remote_key_resource import RemoteKey
 class KeyApiV2Resource(Resource):
     def __init__(self, hs):
         Resource.__init__(self)
-        self.putChild("server", LocalKey(hs))
-        self.putChild("query", RemoteKey(hs))
+        self.putChild(b"server", LocalKey(hs))
+        self.putChild(b"query", RemoteKey(hs))
diff --git a/synapse/rest/key/v2/remote_key_resource.py b/synapse/rest/key/v2/remote_key_resource.py
index 7d67e4b064..eb8782aa6e 100644
--- a/synapse/rest/key/v2/remote_key_resource.py
+++ b/synapse/rest/key/v2/remote_key_resource.py
@@ -103,7 +103,7 @@ class RemoteKey(Resource):
     def async_render_GET(self, request):
         if len(request.postpath) == 1:
             server, = request.postpath
-            query = {server: {}}
+            query = {server.decode('ascii'): {}}
         elif len(request.postpath) == 2:
             server, key_id = request.postpath
             minimum_valid_until_ts = parse_integer(
@@ -112,11 +112,12 @@ class RemoteKey(Resource):
             arguments = {}
             if minimum_valid_until_ts is not None:
                 arguments["minimum_valid_until_ts"] = minimum_valid_until_ts
-            query = {server: {key_id: arguments}}
+            query = {server.decode('ascii'): {key_id.decode('ascii'): arguments}}
         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):
@@ -135,6 +136,7 @@ class RemoteKey(Resource):
     @defer.inlineCallbacks
     def query_keys(self, request, query, query_remote_on_cache_miss=False):
         logger.info("Handling query for keys %r", query)
+
         store_queries = []
         for server_name, key_ids in query.items():
             if (
diff --git a/synapse/rest/media/v0/content_repository.py b/synapse/rest/media/v0/content_repository.py
index f255f2883f..5a426ff2f6 100644
--- a/synapse/rest/media/v0/content_repository.py
+++ b/synapse/rest/media/v0/content_repository.py
@@ -56,7 +56,7 @@ class ContentRepoResource(resource.Resource):
         # servers.
 
         # TODO: A little crude here, we could do this better.
-        filename = request.path.split('/')[-1]
+        filename = request.path.decode('ascii').split('/')[-1]
         # be paranoid
         filename = re.sub("[^0-9A-z.-_]", "", filename)
 
@@ -78,7 +78,7 @@ class ContentRepoResource(resource.Resource):
             # select private. don't bother setting Expires as all our matrix
             # clients are smart enough to be happy with Cache-Control (right?)
             request.setHeader(
-                "Cache-Control", "public,max-age=86400,s-maxage=86400"
+                b"Cache-Control", b"public,max-age=86400,s-maxage=86400"
             )
 
             d = FileSender().beginFileTransfer(f, request)
diff --git a/synapse/rest/media/v1/_base.py b/synapse/rest/media/v1/_base.py
index 65f4bd2910..76e479afa3 100644
--- a/synapse/rest/media/v1/_base.py
+++ b/synapse/rest/media/v1/_base.py
@@ -15,9 +15,8 @@
 
 import logging
 import os
-import urllib
 
-from six.moves.urllib import parse as urlparse
+from six.moves import urllib
 
 from twisted.internet import defer
 from twisted.protocols.basic import FileSender
@@ -35,10 +34,15 @@ def parse_media_id(request):
         # This allows users to append e.g. /test.png to the URL. Useful for
         # clients that parse the URL to see content type.
         server_name, media_id = request.postpath[:2]
+
+        if isinstance(server_name, bytes):
+            server_name = server_name.decode('utf-8')
+            media_id = media_id.decode('utf8')
+
         file_name = None
         if len(request.postpath) > 2:
             try:
-                file_name = urlparse.unquote(request.postpath[-1]).decode("utf-8")
+                file_name = urllib.parse.unquote(request.postpath[-1].decode("utf-8"))
             except UnicodeDecodeError:
                 pass
         return server_name, media_id, file_name
@@ -93,22 +97,18 @@ def add_file_headers(request, media_type, file_size, upload_name):
         file_size (int): Size in bytes of the media, if known.
         upload_name (str): The name of the requested file, if any.
     """
+    def _quote(x):
+        return urllib.parse.quote(x.encode("utf-8"))
+
     request.setHeader(b"Content-Type", media_type.encode("UTF-8"))
     if upload_name:
         if is_ascii(upload_name):
-            request.setHeader(
-                b"Content-Disposition",
-                b"inline; filename=%s" % (
-                    urllib.quote(upload_name.encode("utf-8")),
-                ),
-            )
+            disposition = ("inline; filename=%s" % (_quote(upload_name),)).encode("ascii")
         else:
-            request.setHeader(
-                b"Content-Disposition",
-                b"inline; filename*=utf-8''%s" % (
-                    urllib.quote(upload_name.encode("utf-8")),
-                ),
-            )
+            disposition = (
+                "inline; filename*=utf-8''%s" % (_quote(upload_name),)).encode("ascii")
+
+        request.setHeader(b"Content-Disposition", disposition)
 
     # cache for at least a day.
     # XXX: we might want to turn this off for data we don't want to
diff --git a/synapse/rest/media/v1/download_resource.py b/synapse/rest/media/v1/download_resource.py
index fbfa85f74f..ca90964d1d 100644
--- a/synapse/rest/media/v1/download_resource.py
+++ b/synapse/rest/media/v1/download_resource.py
@@ -47,12 +47,12 @@ class DownloadResource(Resource):
     def _async_render_GET(self, request):
         set_cors_headers(request)
         request.setHeader(
-            "Content-Security-Policy",
-            "default-src 'none';"
-            " script-src 'none';"
-            " plugin-types application/pdf;"
-            " style-src 'unsafe-inline';"
-            " object-src 'self';"
+            b"Content-Security-Policy",
+            b"default-src 'none';"
+            b" script-src 'none';"
+            b" plugin-types application/pdf;"
+            b" style-src 'unsafe-inline';"
+            b" object-src 'self';"
         )
         server_name, media_id, name = parse_media_id(request)
         if server_name == self.server_name:
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index 241c972070..a828ff4438 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -20,7 +20,7 @@ import logging
 import os
 import shutil
 
-from six import iteritems
+from six import PY3, iteritems
 from six.moves.urllib import parse as urlparse
 
 import twisted.internet.error
@@ -397,13 +397,13 @@ class MediaRepository(object):
 
             yield finish()
 
-        media_type = headers["Content-Type"][0]
+        media_type = headers[b"Content-Type"][0].decode('ascii')
 
         time_now_ms = self.clock.time_msec()
 
-        content_disposition = headers.get("Content-Disposition", None)
+        content_disposition = headers.get(b"Content-Disposition", None)
         if content_disposition:
-            _, params = cgi.parse_header(content_disposition[0],)
+            _, params = cgi.parse_header(content_disposition[0].decode('ascii'),)
             upload_name = None
 
             # First check if there is a valid UTF-8 filename
@@ -419,9 +419,13 @@ class MediaRepository(object):
                     upload_name = upload_name_ascii
 
             if upload_name:
-                upload_name = urlparse.unquote(upload_name)
+                if PY3:
+                    upload_name = urlparse.unquote(upload_name)
+                else:
+                    upload_name = urlparse.unquote(upload_name.encode('ascii'))
                 try:
-                    upload_name = upload_name.decode("utf-8")
+                    if isinstance(upload_name, bytes):
+                        upload_name = upload_name.decode("utf-8")
                 except UnicodeDecodeError:
                     upload_name = None
         else:
@@ -755,14 +759,15 @@ class MediaRepositoryResource(Resource):
         Resource.__init__(self)
 
         media_repo = hs.get_media_repository()
-        self.putChild("upload", UploadResource(hs, media_repo))
-        self.putChild("download", DownloadResource(hs, media_repo))
-        self.putChild("thumbnail", ThumbnailResource(
+
+        self.putChild(b"upload", UploadResource(hs, media_repo))
+        self.putChild(b"download", DownloadResource(hs, media_repo))
+        self.putChild(b"thumbnail", ThumbnailResource(
             hs, media_repo, media_repo.media_storage,
         ))
-        self.putChild("identicon", IdenticonResource())
+        self.putChild(b"identicon", IdenticonResource())
         if hs.config.url_preview_enabled:
-            self.putChild("preview_url", PreviewUrlResource(
+            self.putChild(b"preview_url", PreviewUrlResource(
                 hs, media_repo, media_repo.media_storage,
             ))
-        self.putChild("config", MediaConfigResource(hs))
+        self.putChild(b"config", MediaConfigResource(hs))
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
index 778ef97337..cad2dec33a 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -261,7 +261,7 @@ class PreviewUrlResource(Resource):
 
         logger.debug("Calculated OG for %s as %s" % (url, og))
 
-        jsonog = json.dumps(og)
+        jsonog = json.dumps(og).encode('utf8')
 
         # store OG in history-aware DB cache
         yield self.store.store_url_cache(
@@ -301,20 +301,20 @@ class PreviewUrlResource(Resource):
                 logger.warn("Error downloading %s: %r", url, e)
                 raise SynapseError(
                     500, "Failed to download content: %s" % (
-                        traceback.format_exception_only(sys.exc_type, e),
+                        traceback.format_exception_only(sys.exc_info()[0], e),
                     ),
                     Codes.UNKNOWN,
                 )
             yield finish()
 
         try:
-            if "Content-Type" in headers:
-                media_type = headers["Content-Type"][0]
+            if b"Content-Type" in headers:
+                media_type = headers[b"Content-Type"][0].decode('ascii')
             else:
                 media_type = "application/octet-stream"
             time_now_ms = self.clock.time_msec()
 
-            content_disposition = headers.get("Content-Disposition", None)
+            content_disposition = headers.get(b"Content-Disposition", None)
             if content_disposition:
                 _, params = cgi.parse_header(content_disposition[0],)
                 download_name = None