Merge tag 'v0.33.9' 0.34.0rc2

Features
--------

- Include flags to optionally add `m.login.terms` to the registration flow when consent tracking is enabled.
([\#4004](https://github.com/matrix-org/synapse/issues/4004), [\#4133](https://github.com/matrix-org/synapse/issues/4133),
[\#4142](https://github.com/matrix-org/synapse/issues/4142), [\#4184](https://github.com/matrix-org/synapse/issues/4184))
- Support for replacing rooms with new ones ([\#4091](https://github.com/matrix-org/synapse/issues/4091), [\#4099](https://github.com/matrix-org/synapse/issues/4099),
[\#4100](https://github.com/matrix-org/synapse/issues/4100), [\#4101](https://github.com/matrix-org/synapse/issues/4101))

Bugfixes
--------

- Fix exceptions when using the email mailer on Python 3. ([\#4095](https://github.com/matrix-org/synapse/issues/4095))
- Fix e2e key backup with more than 9 backup versions ([\#4113](https://github.com/matrix-org/synapse/issues/4113))
- Searches that request profile info now no longer fail with a 500. ([\#4122](https://github.com/matrix-org/synapse/issues/4122))
- fix return code of empty key backups ([\#4123](https://github.com/matrix-org/synapse/issues/4123))
- If the typing stream ID goes backwards (as on a worker when the master restarts), the worker's typing handler will no longer erroneously report rooms containing new
typing events. ([\#4127](https://github.com/matrix-org/synapse/issues/4127))
- Fix table lock of device_lists_remote_cache which could freeze the application ([\#4132](https://github.com/matrix-org/synapse/issues/4132))
- Fix exception when using state res v2 algorithm ([\#4135](https://github.com/matrix-org/synapse/issues/4135))
- Generating the user consent URI no longer fails on Python 3. ([\#4140](https://github.com/matrix-org/synapse/issues/4140),
[\#4163](https://github.com/matrix-org/synapse/issues/4163))
- Loading URL previews from the DB cache on Postgres will no longer cause Unicode type errors when responding to the request, and URL previews will no longer fail if
the remote server returns a Content-Type header with the chartype in quotes. ([\#4157](https://github.com/matrix-org/synapse/issues/4157))
- The hash_password script now works on Python 3. ([\#4161](https://github.com/matrix-org/synapse/issues/4161))
- Fix noop checks when updating device keys, reducing spurious device list update notifications. ([\#4164](https://github.com/matrix-org/synapse/issues/4164))

Deprecations and Removals
-------------------------

- The disused and un-specced identicon generator has been removed. ([\#4106](https://github.com/matrix-org/synapse/issues/4106))
- The obsolete and non-functional /pull federation endpoint has been removed. ([\#4118](https://github.com/matrix-org/synapse/issues/4118))
- The deprecated v1 key exchange endpoints have been removed. ([\#4119](https://github.com/matrix-org/synapse/issues/4119))
- Synapse will no longer fetch keys using the fallback deprecated v1 key exchange method and will now always use v2.
([\#4120](https://github.com/matrix-org/synapse/issues/4120))

Internal Changes
----------------

- Fix build of Docker image with docker-compose ([\#3778](https://github.com/matrix-org/synapse/issues/3778))
- Delete unreferenced state groups during history purge ([\#4006](https://github.com/matrix-org/synapse/issues/4006))
- The "Received rdata" log messages on workers is now logged at DEBUG, not INFO. ([\#4108](https://github.com/matrix-org/synapse/issues/4108))
- Reduce replication traffic for device lists ([\#4109](https://github.com/matrix-org/synapse/issues/4109))
- Fix `synapse_replication_tcp_protocol_*_commands` metric label to be full command name, rather than just the first character
([\#4110](https://github.com/matrix-org/synapse/issues/4110))
- Log some bits about room creation ([\#4121](https://github.com/matrix-org/synapse/issues/4121))
- Fix `tox` failure on old systems ([\#4124](https://github.com/matrix-org/synapse/issues/4124))
- Add STATE_V2_TEST room version ([\#4128](https://github.com/matrix-org/synapse/issues/4128))
- Clean up event accesses and tests ([\#4137](https://github.com/matrix-org/synapse/issues/4137))
- The default logging config will now set an explicit log file encoding of UTF-8. ([\#4138](https://github.com/matrix-org/synapse/issues/4138))
- Add helpers functions for getting prev and auth events of an event ([\#4139](https://github.com/matrix-org/synapse/issues/4139))
- Add some tests for the HTTP pusher. ([\#4149](https://github.com/matrix-org/synapse/issues/4149))
- add purge_history.sh and purge_remote_media.sh scripts to contrib/ ([\#4155](https://github.com/matrix-org/synapse/issues/4155))
- HTTP tests have been refactored to contain less boilerplate. ([\#4156](https://github.com/matrix-org/synapse/issues/4156))
- Drop incoming events from federation for unknown rooms ([\#4165](https://github.com/matrix-org/synapse/issues/4165))

11 files changed, 242 insertions, 201 deletions

diff --git a/synapse/rest/__init__.py b/synapse/rest/__init__.py
index 4856822a5d..5f35c2d1be 100644
--- a/synapse/rest/__init__.py
+++ b/synapse/rest/__init__.py
@@ -47,6 +47,7 @@ from synapse.rest.client.v2_alpha import (
     register,
     report_event,
     room_keys,
+    room_upgrade_rest_servlet,
     sendtodevice,
     sync,
     tags,
@@ -116,3 +117,4 @@ class ClientRestResource(JsonResource):
         sendtodevice.register_servlets(hs, client_resource)
         user_directory.register_servlets(hs, client_resource)
         groups.register_servlets(hs, client_resource)
+        room_upgrade_rest_servlet.register_servlets(hs, client_resource)
diff --git a/synapse/rest/client/v2_alpha/auth.py b/synapse/rest/client/v2_alpha/auth.py
index 693b303881..a8d8ed6590 100644
--- a/synapse/rest/client/v2_alpha/auth.py
+++ b/synapse/rest/client/v2_alpha/auth.py
@@ -68,6 +68,29 @@ function captchaDone() {
 </html>
 """
 
+TERMS_TEMPLATE = """
+<html>
+<head>
+<title>Authentication</title>
+<meta name='viewport' content='width=device-width, initial-scale=1,
+    user-scalable=no, minimum-scale=1.0, maximum-scale=1.0'>
+<link rel="stylesheet" href="/_matrix/static/client/register/style.css">
+</head>
+<body>
+<form id="registrationForm" method="post" action="%(myurl)s">
+    <div>
+        <p>
+            Please click the button below if you agree to the
+            <a href="%(terms_url)s">privacy policy of this homeserver.</a>
+        </p>
+        <input type="hidden" name="session" value="%(session)s" />
+        <input type="submit" value="Agree" />
+    </div>
+</form>
+</body>
+</html>
+"""
+
 SUCCESS_TEMPLATE = """
 <html>
 <head>
@@ -133,13 +156,34 @@ class AuthRestServlet(RestServlet):
             request.write(html_bytes)
             finish_request(request)
             defer.returnValue(None)
+        elif stagetype == LoginType.TERMS:
+            session = request.args['session'][0]
+
+            html = TERMS_TEMPLATE % {
+                'session': session,
+                'terms_url': "%s/_matrix/consent?v=%s" % (
+                    self.hs.config.public_baseurl,
+                    self.hs.config.user_consent_version,
+                ),
+                'myurl': "%s/auth/%s/fallback/web" % (
+                    CLIENT_V2_ALPHA_PREFIX, LoginType.TERMS
+                ),
+            }
+            html_bytes = html.encode("utf8")
+            request.setResponseCode(200)
+            request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
+            request.setHeader(b"Content-Length", b"%d" % (len(html_bytes),))
+
+            request.write(html_bytes)
+            finish_request(request)
+            defer.returnValue(None)
         else:
             raise SynapseError(404, "Unknown auth stage type")
 
     @defer.inlineCallbacks
     def on_POST(self, request, stagetype):
         yield
-        if stagetype == "m.login.recaptcha":
+        if stagetype == LoginType.RECAPTCHA:
             if ('g-recaptcha-response' not in request.args or
                     len(request.args['g-recaptcha-response'])) == 0:
                 raise SynapseError(400, "No captcha response supplied")
@@ -179,6 +223,41 @@ class AuthRestServlet(RestServlet):
             finish_request(request)
 
             defer.returnValue(None)
+        elif stagetype == LoginType.TERMS:
+            if ('session' not in request.args or
+                    len(request.args['session'])) == 0:
+                raise SynapseError(400, "No session supplied")
+
+            session = request.args['session'][0]
+            authdict = {'session': session}
+
+            success = yield self.auth_handler.add_oob_auth(
+                LoginType.TERMS,
+                authdict,
+                self.hs.get_ip_from_request(request)
+            )
+
+            if success:
+                html = SUCCESS_TEMPLATE
+            else:
+                html = TERMS_TEMPLATE % {
+                    'session': session,
+                    'terms_url': "%s/_matrix/consent?v=%s" % (
+                        self.hs.config.public_baseurl,
+                        self.hs.config.user_consent_version,
+                    ),
+                    'myurl': "%s/auth/%s/fallback/web" % (
+                        CLIENT_V2_ALPHA_PREFIX, LoginType.TERMS
+                    ),
+                }
+            html_bytes = html.encode("utf8")
+            request.setResponseCode(200)
+            request.setHeader(b"Content-Type", b"text/html; charset=utf-8")
+            request.setHeader(b"Content-Length", b"%d" % (len(html_bytes),))
+
+            request.write(html_bytes)
+            finish_request(request)
+            defer.returnValue(None)
         else:
             raise SynapseError(404, "Unknown auth stage type")
 
diff --git a/synapse/rest/client/v2_alpha/register.py b/synapse/rest/client/v2_alpha/register.py
index 192f52e462..0515715f7c 100644
--- a/synapse/rest/client/v2_alpha/register.py
+++ b/synapse/rest/client/v2_alpha/register.py
@@ -359,6 +359,13 @@ class RegisterRestServlet(RestServlet):
                     [LoginType.MSISDN, LoginType.EMAIL_IDENTITY]
                 ])
 
+        # Append m.login.terms to all flows if we're requiring consent
+        if self.hs.config.user_consent_at_registration:
+            new_flows = []
+            for flow in flows:
+                flow.append(LoginType.TERMS)
+            flows.extend(new_flows)
+
         auth_result, params, session_id = yield self.auth_handler.check_auth(
             flows, body, self.hs.get_ip_from_request(request)
         )
@@ -445,6 +452,12 @@ class RegisterRestServlet(RestServlet):
                 params.get("bind_msisdn")
             )
 
+        if auth_result and LoginType.TERMS in auth_result:
+            logger.info("%s has consented to the privacy policy" % registered_user_id)
+            yield self.store.user_set_consent_version(
+                registered_user_id, self.hs.config.user_consent_version,
+            )
+
         defer.returnValue((200, return_dict))
 
     def on_OPTIONS(self, _):
diff --git a/synapse/rest/client/v2_alpha/room_keys.py b/synapse/rest/client/v2_alpha/room_keys.py
index 45b5817d8b..ab3f1bd21a 100644
--- a/synapse/rest/client/v2_alpha/room_keys.py
+++ b/synapse/rest/client/v2_alpha/room_keys.py
@@ -17,7 +17,7 @@ import logging
 
 from twisted.internet import defer
 
-from synapse.api.errors import Codes, SynapseError
+from synapse.api.errors import Codes, NotFoundError, SynapseError
 from synapse.http.servlet import (
     RestServlet,
     parse_json_object_from_request,
@@ -208,10 +208,25 @@ class RoomKeysServlet(RestServlet):
             user_id, version, room_id, session_id
         )
 
+        # Convert room_keys to the right format to return.
         if session_id:
-            room_keys = room_keys['rooms'][room_id]['sessions'][session_id]
+            # If the client requests a specific session, but that session was
+            # not backed up, then return an M_NOT_FOUND.
+            if room_keys['rooms'] == {}:
+                raise NotFoundError("No room_keys found")
+            else:
+                room_keys = room_keys['rooms'][room_id]['sessions'][session_id]
         elif room_id:
-            room_keys = room_keys['rooms'][room_id]
+            # If the client requests all sessions from a room, but no sessions
+            # are found, then return an empty result rather than an error, so
+            # that clients don't have to handle an error condition, and an
+            # empty result is valid.  (Similarly if the client requests all
+            # sessions from the backup, but in that case, room_keys is already
+            # in the right format, so we don't need to do anything about it.)
+            if room_keys['rooms'] == {}:
+                room_keys = {'sessions': {}}
+            else:
+                room_keys = room_keys['rooms'][room_id]
 
         defer.returnValue((200, room_keys))
 
diff --git a/synapse/rest/client/v2_alpha/room_upgrade_rest_servlet.py b/synapse/rest/client/v2_alpha/room_upgrade_rest_servlet.py
new file mode 100644
index 0000000000..e6356101fd
--- /dev/null
+++ b/synapse/rest/client/v2_alpha/room_upgrade_rest_servlet.py
@@ -0,0 +1,89 @@
+# -*- coding: utf-8 -*-
+# Copyright 2016 OpenMarket Ltd
+#
+# 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 logging
+
+from twisted.internet import defer
+
+from synapse.api.constants import KNOWN_ROOM_VERSIONS
+from synapse.api.errors import Codes, SynapseError
+from synapse.http.servlet import (
+    RestServlet,
+    assert_params_in_dict,
+    parse_json_object_from_request,
+)
+
+from ._base import client_v2_patterns
+
+logger = logging.getLogger(__name__)
+
+
+class RoomUpgradeRestServlet(RestServlet):
+    """Handler for room uprade requests.
+
+    Handles requests of the form:
+
+        POST /_matrix/client/r0/rooms/$roomid/upgrade HTTP/1.1
+        Content-Type: application/json
+
+        {
+            "new_version": "2",
+        }
+
+    Creates a new room and shuts down the old one. Returns the ID of the new room.
+
+    Args:
+        hs (synapse.server.HomeServer):
+    """
+    PATTERNS = client_v2_patterns(
+        # /rooms/$roomid/upgrade
+        "/rooms/(?P<room_id>[^/]*)/upgrade$",
+        v2_alpha=False,
+    )
+
+    def __init__(self, hs):
+        super(RoomUpgradeRestServlet, self).__init__()
+        self._hs = hs
+        self._room_creation_handler = hs.get_room_creation_handler()
+        self._auth = hs.get_auth()
+
+    @defer.inlineCallbacks
+    def on_POST(self, request, room_id):
+        requester = yield self._auth.get_user_by_req(request)
+
+        content = parse_json_object_from_request(request)
+        assert_params_in_dict(content, ("new_version", ))
+        new_version = content["new_version"]
+
+        if new_version not in KNOWN_ROOM_VERSIONS:
+            raise SynapseError(
+                400,
+                "Your homeserver does not support this room version",
+                Codes.UNSUPPORTED_ROOM_VERSION,
+            )
+
+        new_room_id = yield self._room_creation_handler.upgrade_room(
+            requester, room_id, new_version
+        )
+
+        ret = {
+            "replacement_room": new_room_id,
+        }
+
+        defer.returnValue((200, ret))
+
+
+def register_servlets(hs, http_server):
+    RoomUpgradeRestServlet(hs).register(http_server)
diff --git a/synapse/rest/consent/consent_resource.py b/synapse/rest/consent/consent_resource.py
index 7362e1858d..ad525b22e1 100644
--- a/synapse/rest/consent/consent_resource.py
+++ b/synapse/rest/consent/consent_resource.py
@@ -137,27 +137,36 @@ class ConsentResource(Resource):
             request (twisted.web.http.Request):
         """
 
-        version = parse_string(request, "v",
-                               default=self._default_consent_version)
-        username = parse_string(request, "u", required=True)
-        userhmac = parse_string(request, "h", required=True, encoding=None)
+        version = parse_string(request, "v", default=self._default_consent_version)
+        username = parse_string(request, "u", required=False, default="")
+        userhmac = None
+        has_consented = False
+        public_version = username == ""
+        if not public_version:
+            userhmac_bytes = parse_string(request, "h", required=True, encoding=None)
 
-        self._check_hash(username, userhmac)
+            self._check_hash(username, userhmac_bytes)
 
-        if username.startswith('@'):
-            qualified_user_id = username
-        else:
-            qualified_user_id = UserID(username, self.hs.hostname).to_string()
+            if username.startswith('@'):
+                qualified_user_id = username
+            else:
+                qualified_user_id = UserID(username, self.hs.hostname).to_string()
 
-        u = yield self.store.get_user_by_id(qualified_user_id)
-        if u is None:
-            raise NotFoundError("Unknown user")
+            u = yield self.store.get_user_by_id(qualified_user_id)
+            if u is None:
+                raise NotFoundError("Unknown user")
+
+            has_consented = u["consent_version"] == version
+            userhmac = userhmac_bytes.decode("ascii")
 
         try:
             self._render_template(
                 request, "%s.html" % (version,),
-                user=username, userhmac=userhmac, version=version,
-                has_consented=(u["consent_version"] == version),
+                user=username,
+                userhmac=userhmac,
+                version=version,
+                has_consented=has_consented,
+                public_version=public_version,
             )
         except TemplateNotFound:
             raise NotFoundError("Unknown policy version")
@@ -223,7 +232,7 @@ class ConsentResource(Resource):
             key=self._hmac_secret,
             msg=userid.encode('utf-8'),
             digestmod=sha256,
-        ).hexdigest()
+        ).hexdigest().encode('ascii')
 
         if not compare_digest(want_mac, userhmac):
             raise SynapseError(http_client.FORBIDDEN, "HMAC incorrect")
diff --git a/synapse/rest/key/v1/__init__.py b/synapse/rest/key/v1/__init__.py
deleted file mode 100644
index fe0ac3f8e9..0000000000
--- a/synapse/rest/key/v1/__init__.py
+++ /dev/null
@@ -1,14 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2015, 2016 OpenMarket Ltd
-#
-# 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.
diff --git a/synapse/rest/key/v1/server_key_resource.py b/synapse/rest/key/v1/server_key_resource.py
deleted file mode 100644
index 38eb2ee23f..0000000000
--- a/synapse/rest/key/v1/server_key_resource.py
+++ /dev/null
@@ -1,92 +0,0 @@
-# -*- coding: utf-8 -*-
-# Copyright 2014-2016 OpenMarket Ltd
-#
-# 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 logging
-
-from canonicaljson import encode_canonical_json
-from signedjson.sign import sign_json
-from unpaddedbase64 import encode_base64
-
-from OpenSSL import crypto
-from twisted.web.resource import Resource
-
-from synapse.http.server import respond_with_json_bytes
-
-logger = logging.getLogger(__name__)
-
-
-class LocalKey(Resource):
-    """HTTP resource containing encoding the TLS X.509 certificate and NACL
-    signature verification keys for this server::
-
-        GET /key HTTP/1.1
-
-        HTTP/1.1 200 OK
-        Content-Type: application/json
-        {
-            "server_name": "this.server.example.com"
-            "verify_keys": {
-                "algorithm:version": # base64 encoded NACL verification key.
-            },
-            "tls_certificate": # base64 ASN.1 DER encoded X.509 tls cert.
-            "signatures": {
-                "this.server.example.com": {
-                   "algorithm:version": # NACL signature for this server.
-                }
-            }
-        }
-    """
-
-    def __init__(self, hs):
-        self.response_body = encode_canonical_json(
-            self.response_json_object(hs.config)
-        )
-        Resource.__init__(self)
-
-    @staticmethod
-    def response_json_object(server_config):
-        verify_keys = {}
-        for key in server_config.signing_key:
-            verify_key_bytes = key.verify_key.encode()
-            key_id = "%s:%s" % (key.alg, key.version)
-            verify_keys[key_id] = encode_base64(verify_key_bytes)
-
-        x509_certificate_bytes = crypto.dump_certificate(
-            crypto.FILETYPE_ASN1,
-            server_config.tls_certificate
-        )
-        json_object = {
-            u"server_name": server_config.server_name,
-            u"verify_keys": verify_keys,
-            u"tls_certificate": encode_base64(x509_certificate_bytes)
-        }
-        for key in server_config.signing_key:
-            json_object = sign_json(
-                json_object,
-                server_config.server_name,
-                key,
-            )
-
-        return json_object
-
-    def render_GET(self, request):
-        return respond_with_json_bytes(
-            request, 200, self.response_body,
-        )
-
-    def getChild(self, name, request):
-        if name == b'':
-            return self
diff --git a/synapse/rest/media/v1/identicon_resource.py b/synapse/rest/media/v1/identicon_resource.py
deleted file mode 100644
index bdbd8d50dd..0000000000
--- a/synapse/rest/media/v1/identicon_resource.py
+++ /dev/null
@@ -1,68 +0,0 @@
-# Copyright 2015, 2016 OpenMarket Ltd
-#
-# 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.
-
-from pydenticon import Generator
-
-from twisted.web.resource import Resource
-
-from synapse.http.servlet import parse_integer
-
-FOREGROUND = [
-    "rgb(45,79,255)",
-    "rgb(254,180,44)",
-    "rgb(226,121,234)",
-    "rgb(30,179,253)",
-    "rgb(232,77,65)",
-    "rgb(49,203,115)",
-    "rgb(141,69,170)"
-]
-
-BACKGROUND = "rgb(224,224,224)"
-SIZE = 5
-
-
-class IdenticonResource(Resource):
-    isLeaf = True
-
-    def __init__(self):
-        Resource.__init__(self)
-        self.generator = Generator(
-            SIZE, SIZE, foreground=FOREGROUND, background=BACKGROUND,
-        )
-
-    def generate_identicon(self, name, width, height):
-        v_padding = width % SIZE
-        h_padding = height % SIZE
-        top_padding = v_padding // 2
-        left_padding = h_padding // 2
-        bottom_padding = v_padding - top_padding
-        right_padding = h_padding - left_padding
-        width -= v_padding
-        height -= h_padding
-        padding = (top_padding, bottom_padding, left_padding, right_padding)
-        identicon = self.generator.generate(
-            name, width, height, padding=padding
-        )
-        return identicon
-
-    def render_GET(self, request):
-        name = "/".join(request.postpath)
-        width = parse_integer(request, "width", default=96)
-        height = parse_integer(request, "height", default=96)
-        identicon_bytes = self.generate_identicon(name, width, height)
-        request.setHeader(b"Content-Type", b"image/png")
-        request.setHeader(
-            b"Cache-Control", b"public,max-age=86400,s-maxage=86400"
-        )
-        return identicon_bytes
diff --git a/synapse/rest/media/v1/media_repository.py b/synapse/rest/media/v1/media_repository.py
index 08b1867fab..d6c5f07af0 100644
--- a/synapse/rest/media/v1/media_repository.py
+++ b/synapse/rest/media/v1/media_repository.py
@@ -45,7 +45,6 @@ from ._base import FileInfo, respond_404, respond_with_responder
 from .config_resource import MediaConfigResource
 from .download_resource import DownloadResource
 from .filepath import MediaFilePaths
-from .identicon_resource import IdenticonResource
 from .media_storage import MediaStorage
 from .preview_url_resource import PreviewUrlResource
 from .storage_provider import StorageProviderWrapper
@@ -769,7 +768,6 @@ class MediaRepositoryResource(Resource):
         self.putChild(b"thumbnail", ThumbnailResource(
             hs, media_repo, media_repo.media_storage,
         ))
-        self.putChild(b"identicon", IdenticonResource())
         if hs.config.url_preview_enabled:
             self.putChild(b"preview_url", PreviewUrlResource(
                 hs, media_repo, media_repo.media_storage,
diff --git a/synapse/rest/media/v1/preview_url_resource.py b/synapse/rest/media/v1/preview_url_resource.py
index 1a7bfd6b56..91d1dafe64 100644
--- a/synapse/rest/media/v1/preview_url_resource.py
+++ b/synapse/rest/media/v1/preview_url_resource.py
@@ -12,6 +12,7 @@
 # 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 cgi
 import datetime
 import errno
@@ -24,6 +25,7 @@ import shutil
 import sys
 import traceback
 
+import six
 from six import string_types
 from six.moves import urllib_parse as urlparse
 
@@ -98,7 +100,7 @@ class PreviewUrlResource(Resource):
         # XXX: if get_user_by_req fails, what should we do in an async render?
         requester = yield self.auth.get_user_by_req(request)
         url = parse_string(request, "url")
-        if "ts" in request.args:
+        if b"ts" in request.args:
             ts = parse_integer(request, "ts")
         else:
             ts = self.clock.time_msec()
@@ -180,7 +182,12 @@ class PreviewUrlResource(Resource):
             cache_result["expires_ts"] > ts and
             cache_result["response_code"] / 100 == 2
         ):
-            defer.returnValue(cache_result["og"])
+            # It may be stored as text in the database, not as bytes (such as
+            # PostgreSQL). If so, encode it back before handing it on.
+            og = cache_result["og"]
+            if isinstance(og, six.text_type):
+                og = og.encode('utf8')
+            defer.returnValue(og)
             return
 
         media_info = yield self._download_url(url, user)
@@ -213,14 +220,17 @@ class PreviewUrlResource(Resource):
         elif _is_html(media_info['media_type']):
             # TODO: somehow stop a big HTML tree from exploding synapse's RAM
 
-            file = open(media_info['filename'])
-            body = file.read()
-            file.close()
+            with open(media_info['filename'], 'rb') as file:
+                body = file.read()
 
             # clobber the encoding from the content-type, or default to utf-8
             # XXX: this overrides any <meta/> or XML charset headers in the body
             # which may pose problems, but so far seems to work okay.
-            match = re.match(r'.*; *charset=(.*?)(;|$)', media_info['media_type'], re.I)
+            match = re.match(
+                r'.*; *charset="?(.*?)"?(;|$)',
+                media_info['media_type'],
+                re.I
+            )
             encoding = match.group(1) if match else "utf-8"
 
             og = decode_and_calc_og(body, media_info['uri'], encoding)