text: # Copyright 2018 New Vector Ltd
  # Copyright 2021 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 base64
  import json
  import os
  import re
  from typing import Any, Dict, Optional, Sequence, Tuple, Type
  from urllib.parse import quote, urlencode
  
  from twisted.internet._resolver import HostResolution
  from twisted.internet.address import IPv4Address, IPv6Address
  from twisted.internet.error import DNSLookupError
  from twisted.internet.interfaces import IAddress, IResolutionReceiver
  from twisted.test.proto_helpers import AccumulatingProtocol, MemoryReactor
  
  from synapse.config.oembed import OEmbedEndpointConfig
  from synapse.rest.media.v1.media_repository import MediaRepositoryResource
  from synapse.rest.media.v1.preview_url_resource import IMAGE_CACHE_EXPIRY_MS
  from synapse.server import HomeServer
  from synapse.types import JsonDict
  from synapse.util import Clock
  from synapse.util.stringutils import parse_and_validate_mxc_uri
  
  from tests import unittest
  from tests.server import FakeTransport
  from tests.test_utils import SMALL_PNG
  from tests.utils import MockClock
  
  try:
      import lxml
  except ImportError:
      lxml = None
  
  
  class URLPreviewTests(unittest.HomeserverTestCase):
      if not lxml:
          skip = "url preview feature requires lxml"
  
      hijack_auth = True
      user_id = "@test:user"
      end_content = (
          b"<html><head>"
          b'<meta property="og:title" content="~matrix~" />'
          b'<meta property="og:description" content="hi" />'
          b"</head></html>"
      )
  
      def make_homeserver(self, reactor: MemoryReactor, clock: Clock) -> HomeServer:
  
          config = self.default_config()
          config["url_preview_enabled"] = True
          config["max_spider_size"] = 9999999
          config["url_preview_ip_range_blacklist"] = (
              "192.168.1.1",
              "1.0.0.0/8",
              "3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff",
              "2001:800::/21",
          )
          config["url_preview_ip_range_whitelist"] = ("1.1.1.1",)
          config["url_preview_accept_language"] = [
              "en-UK",
              "en-US;q=0.9",
              "fr;q=0.8",
              "*;q=0.7",
          ]
  
          self.storage_path = self.mktemp()
          self.media_store_path = self.mktemp()
          os.mkdir(self.storage_path)
          os.mkdir(self.media_store_path)
          config["media_store_path"] = self.media_store_path
  
          provider_config = {
              "module": "synapse.rest.media.v1.storage_provider.FileStorageProviderBackend",
              "store_local": True,
              "store_synchronous": False,
              "store_remote": True,
              "config": {"directory": self.storage_path},
          }
  
          config["media_storage_providers"] = [provider_config]
  
          hs = self.setup_test_homeserver(config=config)
  
          # After the hs is created, modify the parsed oEmbed config (to avoid
          # messing with files).
          #
          # Note that HTTP URLs are used to avoid having to deal with TLS in tests.
          hs.config.oembed.oembed_patterns = [
              OEmbedEndpointConfig(
                  api_endpoint="http://publish.twitter.com/oembed",
                  url_patterns=[
                      re.compile(r"http://twitter\.com/.+/status/.+"),
                  ],
                  formats=None,
              ),
              OEmbedEndpointConfig(
                  api_endpoint="http://www.hulu.com/api/oembed.{format}",
                  url_patterns=[
                      re.compile(r"http://www\.hulu\.com/watch/.+"),
                  ],
                  formats=["json"],
              ),
          ]
  
          return hs
  
      def prepare(self, reactor: MemoryReactor, clock: Clock, hs: HomeServer) -> None:
  
          self.media_repo = hs.get_media_repository_resource()
          self.preview_url = self.media_repo.children[b"preview_url"]
  
          self.lookups: Dict[str, Any] = {}
  
          class Resolver:
              def resolveHostName(
                  _self,
                  resolutionReceiver: IResolutionReceiver,
                  hostName: str,
                  portNumber: int = 0,
                  addressTypes: Optional[Sequence[Type[IAddress]]] = None,
                  transportSemantics: str = "TCP",
              ) -> IResolutionReceiver:
  
                  resolution = HostResolution(hostName)
                  resolutionReceiver.resolutionBegan(resolution)
                  if hostName not in self.lookups:
                      raise DNSLookupError("OH NO")
  
                  for i in self.lookups[hostName]:
                      resolutionReceiver.addressResolved(i[0]("TCP", i[1], portNumber))
                  resolutionReceiver.resolutionComplete()
                  return resolutionReceiver
  
          self.reactor.nameResolver = Resolver()  # type: ignore[assignment]
  
      def create_test_resource(self) -> MediaRepositoryResource:
          return self.hs.get_media_repository_resource()
  
      def _assert_small_png(self, json_body: JsonDict) -> None:
          """Assert properties from the SMALL_PNG test image."""
          self.assertTrue(json_body["og:image"].startswith("mxc://"))
          self.assertEqual(json_body["og:image:height"], 1)
          self.assertEqual(json_body["og:image:width"], 1)
          self.assertEqual(json_body["og:image:type"], "image/png")
          self.assertEqual(json_body["matrix:image:size"], 67)
  
      def test_cache_returns_correct_type(self) -> None:
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://matrix.org",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
              % (len(self.end_content),)
              + self.end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
          self.assertEqual(
              channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
          )
  
          # Check the cache returns the correct response
          channel = self.make_request(
              "GET", "preview_url?url=http://matrix.org", shorthand=False
          )
  
          # Check the cache response has the same content
          self.assertEqual(channel.code, 200)
          self.assertEqual(
              channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
          )
  
          # Clear the in-memory cache
          self.assertIn("http://matrix.org", self.preview_url._cache)
          self.preview_url._cache.pop("http://matrix.org")
          self.assertNotIn("http://matrix.org", self.preview_url._cache)
  
          # Check the database cache returns the correct response
          channel = self.make_request(
              "GET", "preview_url?url=http://matrix.org", shorthand=False
          )
  
          # Check the cache response has the same content
          self.assertEqual(channel.code, 200)
          self.assertEqual(
              channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
          )
  
      def test_non_ascii_preview_httpequiv(self) -> None:
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          end_content = (
              b"<html><head>"
              b'<meta http-equiv="Content-Type" content="text/html; charset=windows-1251"/>'
              b'<meta property="og:title" content="\xe4\xea\xe0" />'
              b'<meta property="og:description" content="hi" />'
              b"</head></html>"
          )
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://matrix.org",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: text/html; charset="utf8"\r\n\r\n'
              )
              % (len(end_content),)
              + end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
          self.assertEqual(channel.json_body["og:title"], "\u0434\u043a\u0430")
  
      def test_video_rejected(self) -> None:
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          end_content = b"anything"
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://matrix.org",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b"Content-Type: video/mp4\r\n\r\n"
              )
              % (len(end_content))
              + end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 502)
          self.assertEqual(
              channel.json_body,
              {
                  "errcode": "M_UNKNOWN",
                  "error": "Requested file's content type not allowed for this operation: video/mp4",
              },
          )
  
      def test_audio_rejected(self) -> None:
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          end_content = b"anything"
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://matrix.org",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b"Content-Type: audio/aac\r\n\r\n"
              )
              % (len(end_content))
              + end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 502)
          self.assertEqual(
              channel.json_body,
              {
                  "errcode": "M_UNKNOWN",
                  "error": "Requested file's content type not allowed for this operation: audio/aac",
              },
          )
  
      def test_non_ascii_preview_content_type(self) -> None:
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          end_content = (
              b"<html><head>"
              b'<meta property="og:title" content="\xe4\xea\xe0" />'
              b'<meta property="og:description" content="hi" />'
              b"</head></html>"
          )
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://matrix.org",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: text/html; charset="windows-1251"\r\n\r\n'
              )
              % (len(end_content),)
              + end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
          self.assertEqual(channel.json_body["og:title"], "\u0434\u043a\u0430")
  
      def test_overlong_title(self) -> None:
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          end_content = (
              b"<html><head>"
              b"<title>" + b"x" * 2000 + b"</title>"
              b'<meta property="og:description" content="hi" />'
              b"</head></html>"
          )
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://matrix.org",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: text/html; charset="windows-1251"\r\n\r\n'
              )
              % (len(end_content),)
              + end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
          res = channel.json_body
          # We should only see the `og:description` field, as `title` is too long and should be stripped out
          self.assertCountEqual(["og:description"], res.keys())
  
      def test_ipaddr(self) -> None:
          """
          IP addresses can be previewed directly.
          """
          self.lookups["example.com"] = [(IPv4Address, "10.1.2.3")]
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://example.com",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
              % (len(self.end_content),)
              + self.end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
          self.assertEqual(
              channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
          )
  
      def test_blacklisted_ip_specific(self) -> None:
          """
          Blacklisted IP addresses, found via DNS, are not spidered.
          """
          self.lookups["example.com"] = [(IPv4Address, "192.168.1.1")]
  
          channel = self.make_request(
              "GET", "preview_url?url=http://example.com", shorthand=False
          )
  
          # No requests made.
          self.assertEqual(len(self.reactor.tcpClients), 0)
          self.assertEqual(channel.code, 502)
          self.assertEqual(
              channel.json_body,
              {
                  "errcode": "M_UNKNOWN",
                  "error": "DNS resolution failure during URL preview generation",
              },
          )
  
      def test_blacklisted_ip_range(self) -> None:
          """
          Blacklisted IP ranges, IPs found over DNS, are not spidered.
          """
          self.lookups["example.com"] = [(IPv4Address, "1.1.1.2")]
  
          channel = self.make_request(
              "GET", "preview_url?url=http://example.com", shorthand=False
          )
  
          self.assertEqual(channel.code, 502)
          self.assertEqual(
              channel.json_body,
              {
                  "errcode": "M_UNKNOWN",
                  "error": "DNS resolution failure during URL preview generation",
              },
          )
  
      def test_blacklisted_ip_specific_direct(self) -> None:
          """
          Blacklisted IP addresses, accessed directly, are not spidered.
          """
          channel = self.make_request(
              "GET", "preview_url?url=http://192.168.1.1", shorthand=False
          )
  
          # No requests made.
          self.assertEqual(len(self.reactor.tcpClients), 0)
          self.assertEqual(
              channel.json_body,
              {
                  "errcode": "M_UNKNOWN",
                  "error": "IP address blocked by IP blacklist entry",
              },
          )
          self.assertEqual(channel.code, 403)
  
      def test_blacklisted_ip_range_direct(self) -> None:
          """
          Blacklisted IP ranges, accessed directly, are not spidered.
          """
          channel = self.make_request(
              "GET", "preview_url?url=http://1.1.1.2", shorthand=False
          )
  
          self.assertEqual(channel.code, 403)
          self.assertEqual(
              channel.json_body,
              {
                  "errcode": "M_UNKNOWN",
                  "error": "IP address blocked by IP blacklist entry",
              },
          )
  
      def test_blacklisted_ip_range_whitelisted_ip(self) -> None:
          """
          Blacklisted but then subsequently whitelisted IP addresses can be
          spidered.
          """
          self.lookups["example.com"] = [(IPv4Address, "1.1.1.1")]
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://example.com",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
  
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
  
          client.dataReceived(
              b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
              % (len(self.end_content),)
              + self.end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
          self.assertEqual(
              channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
          )
  
      def test_blacklisted_ip_with_external_ip(self) -> None:
          """
          If a hostname resolves a blacklisted IP, even if there's a
          non-blacklisted one, it will be rejected.
          """
          # Hardcode the URL resolving to the IP we want.
          self.lookups["example.com"] = [
              (IPv4Address, "1.1.1.2"),
              (IPv4Address, "10.1.2.3"),
          ]
  
          channel = self.make_request(
              "GET", "preview_url?url=http://example.com", shorthand=False
          )
          self.assertEqual(channel.code, 502)
          self.assertEqual(
              channel.json_body,
              {
                  "errcode": "M_UNKNOWN",
                  "error": "DNS resolution failure during URL preview generation",
              },
          )
  
      def test_blacklisted_ipv6_specific(self) -> None:
          """
          Blacklisted IP addresses, found via DNS, are not spidered.
          """
          self.lookups["example.com"] = [
              (IPv6Address, "3fff:ffff:ffff:ffff:ffff:ffff:ffff:ffff")
          ]
  
          channel = self.make_request(
              "GET", "preview_url?url=http://example.com", shorthand=False
          )
  
          # No requests made.
          self.assertEqual(len(self.reactor.tcpClients), 0)
          self.assertEqual(channel.code, 502)
          self.assertEqual(
              channel.json_body,
              {
                  "errcode": "M_UNKNOWN",
                  "error": "DNS resolution failure during URL preview generation",
              },
          )
  
      def test_blacklisted_ipv6_range(self) -> None:
          """
          Blacklisted IP ranges, IPs found over DNS, are not spidered.
          """
          self.lookups["example.com"] = [(IPv6Address, "2001:800::1")]
  
          channel = self.make_request(
              "GET", "preview_url?url=http://example.com", shorthand=False
          )
  
          self.assertEqual(channel.code, 502)
          self.assertEqual(
              channel.json_body,
              {
                  "errcode": "M_UNKNOWN",
                  "error": "DNS resolution failure during URL preview generation",
              },
          )
  
      def test_OPTIONS(self) -> None:
          """
          OPTIONS returns the OPTIONS.
          """
          channel = self.make_request(
              "OPTIONS", "preview_url?url=http://example.com", shorthand=False
          )
          self.assertEqual(channel.code, 200)
          self.assertEqual(channel.json_body, {})
  
      def test_accept_language_config_option(self) -> None:
          """
          Accept-Language header is sent to the remote server
          """
          self.lookups["example.com"] = [(IPv4Address, "10.1.2.3")]
  
          # Build and make a request to the server
          channel = self.make_request(
              "GET",
              "preview_url?url=http://example.com",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          # Extract Synapse's tcp client
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
  
          # Build a fake remote server to reply with
          server = AccumulatingProtocol()
  
          # Connect the two together
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
  
          # Tell Synapse that it has received some data from the remote server
          client.dataReceived(
              b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
              % (len(self.end_content),)
              + self.end_content
          )
  
          # Move the reactor along until we get a response on our original channel
          self.pump()
          self.assertEqual(channel.code, 200)
          self.assertEqual(
              channel.json_body, {"og:title": "~matrix~", "og:description": "hi"}
          )
  
          # Check that the server received the Accept-Language header as part
          # of the request from Synapse
          self.assertIn(
              (
                  b"Accept-Language: en-UK\r\n"
                  b"Accept-Language: en-US;q=0.9\r\n"
                  b"Accept-Language: fr;q=0.8\r\n"
                  b"Accept-Language: *;q=0.7"
              ),
              server.data,
          )
  
      def test_nonexistent_image(self) -> None:
          """If the preview image doesn't exist, ensure some data is returned."""
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          end_content = (
              b"""<html><body><img src="http://cdn.matrix.org/foo.jpg"></body></html>"""
          )
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://matrix.org",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: text/html; charset="utf8"\r\n\r\n'
              )
              % (len(end_content),)
              + end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
  
          # The image should not be in the result.
          self.assertNotIn("og:image", channel.json_body)
  
      def test_data_url(self) -> None:
          """
          Requesting to preview a data URL is not supported.
          """
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          data = base64.b64encode(SMALL_PNG).decode()
  
          query_params = urlencode(
              {
                  "url": f'<html><head><img src="data:image/png;base64,{data}" /></head></html>'
              }
          )
  
          channel = self.make_request(
              "GET",
              f"preview_url?{query_params}",
              shorthand=False,
          )
          self.pump()
  
          self.assertEqual(channel.code, 500)
  
      def test_inline_data_url(self) -> None:
          """
          An inline image (as a data URL) should be parsed properly.
          """
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          data = base64.b64encode(SMALL_PNG)
  
          end_content = (
              b"<html><head>" b'<img src="data:image/png;base64,%s" />' b"</head></html>"
          ) % (data,)
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://matrix.org",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: text/html; charset="utf8"\r\n\r\n'
              )
              % (len(end_content),)
              + end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
          self._assert_small_png(channel.json_body)
  
      def test_oembed_photo(self) -> None:
          """Test an oEmbed endpoint which returns a 'photo' type which redirects the preview to a new URL."""
          self.lookups["publish.twitter.com"] = [(IPv4Address, "10.1.2.3")]
          self.lookups["cdn.twitter.com"] = [(IPv4Address, "10.1.2.3")]
  
          result = {
              "version": "1.0",
              "type": "photo",
              "url": "http://cdn.twitter.com/matrixdotorg",
          }
          oembed_content = json.dumps(result).encode("utf-8")
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://twitter.com/matrixdotorg/status/12345",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: application/json; charset="utf8"\r\n\r\n'
              )
              % (len(oembed_content),)
              + oembed_content
          )
  
          self.pump()
  
          # Ensure a second request is made to the photo URL.
          client = self.reactor.tcpClients[1][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b"Content-Type: image/png\r\n\r\n"
              )
              % (len(SMALL_PNG),)
              + SMALL_PNG
          )
  
          self.pump()
  
          # Ensure the URL is what was requested.
          self.assertIn(b"/matrixdotorg", server.data)
  
          self.assertEqual(channel.code, 200)
          body = channel.json_body
          self.assertEqual(body["og:url"], "http://twitter.com/matrixdotorg/status/12345")
          self._assert_small_png(body)
  
      def test_oembed_rich(self) -> None:
          """Test an oEmbed endpoint which returns HTML content via the 'rich' type."""
          self.lookups["publish.twitter.com"] = [(IPv4Address, "10.1.2.3")]
  
          result = {
              "version": "1.0",
              "type": "rich",
              # Note that this provides the author, not the title.
              "author_name": "Alice",
              "html": "<div>Content Preview</div>",
          }
          end_content = json.dumps(result).encode("utf-8")
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://twitter.com/matrixdotorg/status/12345",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: application/json; charset="utf8"\r\n\r\n'
              )
              % (len(end_content),)
              + end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
          body = channel.json_body
          self.assertEqual(
              body,
              {
                  "og:url": "http://twitter.com/matrixdotorg/status/12345",
                  "og:title": "Alice",
                  "og:description": "Content Preview",
              },
          )
  
      def test_oembed_format(self) -> None:
          """Test an oEmbed endpoint which requires the format in the URL."""
          self.lookups["www.hulu.com"] = [(IPv4Address, "10.1.2.3")]
  
          result = {
              "version": "1.0",
              "type": "rich",
              "html": "<div>Content Preview</div>",
          }
          end_content = json.dumps(result).encode("utf-8")
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://www.hulu.com/watch/12345",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: application/json; charset="utf8"\r\n\r\n'
              )
              % (len(end_content),)
              + end_content
          )
  
          self.pump()
  
          # The {format} should have been turned into json.
          self.assertIn(b"/api/oembed.json", server.data)
          # A URL parameter of format=json should be provided.
          self.assertIn(b"format=json", server.data)
  
          self.assertEqual(channel.code, 200)
          body = channel.json_body
          self.assertEqual(
              body,
              {
                  "og:url": "http://www.hulu.com/watch/12345",
                  "og:description": "Content Preview",
              },
          )
  
      def test_oembed_autodiscovery(self) -> None:
          """
          Autodiscovery works by finding the link in the HTML response and then requesting an oEmbed URL.
          1. Request a preview of a URL which is not known to the oEmbed code.
          2. It returns HTML including a link to an oEmbed preview.
          3. The oEmbed preview is requested and returns a URL for an image.
          4. The image is requested for thumbnailing.
          """
          # This is a little cheesy in that we use the www subdomain (which isn't the
          # list of oEmbed patterns) to get "raw" HTML response.
          self.lookups["www.twitter.com"] = [(IPv4Address, "10.1.2.3")]
          self.lookups["publish.twitter.com"] = [(IPv4Address, "10.1.2.3")]
          self.lookups["cdn.twitter.com"] = [(IPv4Address, "10.1.2.3")]
  
          result = b"""
          <link rel="alternate" type="application/json+oembed"
              href="http://publish.twitter.com/oembed?url=http%3A%2F%2Fcdn.twitter.com%2Fmatrixdotorg%2Fstatus%2F12345&format=json"
              title="matrixdotorg" />
          """
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://www.twitter.com/matrixdotorg/status/12345",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: text/html; charset="utf8"\r\n\r\n'
              )
              % (len(result),)
              + result
          )
  
          self.pump()
  
          # The oEmbed response.
          result2 = {
              "version": "1.0",
              "type": "photo",
              "url": "http://cdn.twitter.com/matrixdotorg",
          }
          oembed_content = json.dumps(result2).encode("utf-8")
  
          # Ensure a second request is made to the oEmbed URL.
          client = self.reactor.tcpClients[1][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b'Content-Type: application/json; charset="utf8"\r\n\r\n'
              )
              % (len(oembed_content),)
              + oembed_content
          )
  
          self.pump()
  
          # Ensure the URL is what was requested.
          self.assertIn(b"/oembed?", server.data)
  
          # Ensure a third request is made to the photo URL.
          client = self.reactor.tcpClients[2][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              (
                  b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\n"
                  b"Content-Type: image/png\r\n\r\n"
              )
              % (len(SMALL_PNG),)
              + SMALL_PNG
          )
  
          self.pump()
  
          # Ensure the URL is what was requested.
          self.assertIn(b"/matrixdotorg", server.data)
  
          self.assertEqual(channel.code, 200)
          body = channel.json_body
          self.assertEqual(
              body["og:url"], "http://www.twitter.com/matrixdotorg/status/12345"
          )
          self._assert_small_png(body)
  
      def _download_image(self) -> Tuple[str, str]:
          """Downloads an image into the URL cache.
          Returns:
              A (host, media_id) tuple representing the MXC URI of the image.
          """
          self.lookups["cdn.twitter.com"] = [(IPv4Address, "10.1.2.3")]
  
          channel = self.make_request(
              "GET",
              "preview_url?url=http://cdn.twitter.com/matrixdotorg",
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: image/png\r\n\r\n"
              % (len(SMALL_PNG),)
              + SMALL_PNG
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
          body = channel.json_body
          mxc_uri = body["og:image"]
          host, _port, media_id = parse_and_validate_mxc_uri(mxc_uri)
          self.assertIsNone(_port)
          return host, media_id
  
      def test_storage_providers_exclude_files(self) -> None:
          """Test that files are not stored in or fetched from storage providers."""
          host, media_id = self._download_image()
  
          rel_file_path = self.preview_url.filepaths.url_cache_filepath_rel(media_id)
          media_store_path = os.path.join(self.media_store_path, rel_file_path)
          storage_provider_path = os.path.join(self.storage_path, rel_file_path)
  
          # Check storage
          self.assertTrue(os.path.isfile(media_store_path))
          self.assertFalse(
              os.path.isfile(storage_provider_path),
              "URL cache file was unexpectedly stored in a storage provider",
          )
  
          # Check fetching
          channel = self.make_request(
              "GET",
              f"download/{host}/{media_id}",
              shorthand=False,
              await_result=False,
          )
          self.pump()
          self.assertEqual(channel.code, 200)
  
          # Move cached file into the storage provider
          os.makedirs(os.path.dirname(storage_provider_path), exist_ok=True)
          os.rename(media_store_path, storage_provider_path)
  
          channel = self.make_request(
              "GET",
              f"download/{host}/{media_id}",
              shorthand=False,
              await_result=False,
          )
          self.pump()
          self.assertEqual(
              channel.code,
              404,
              "URL cache file was unexpectedly retrieved from a storage provider",
          )
  
      def test_storage_providers_exclude_thumbnails(self) -> None:
          """Test that thumbnails are not stored in or fetched from storage providers."""
          host, media_id = self._download_image()
  
          rel_thumbnail_path = (
              self.preview_url.filepaths.url_cache_thumbnail_directory_rel(media_id)
          )
          media_store_thumbnail_path = os.path.join(
              self.media_store_path, rel_thumbnail_path
          )
          storage_provider_thumbnail_path = os.path.join(
              self.storage_path, rel_thumbnail_path
          )
  
          # Check storage
          self.assertTrue(os.path.isdir(media_store_thumbnail_path))
          self.assertFalse(
              os.path.isdir(storage_provider_thumbnail_path),
              "URL cache thumbnails were unexpectedly stored in a storage provider",
          )
  
          # Check fetching
          channel = self.make_request(
              "GET",
              f"thumbnail/{host}/{media_id}?width=32&height=32&method=scale",
              shorthand=False,
              await_result=False,
          )
          self.pump()
          self.assertEqual(channel.code, 200)
  
          # Remove the original, otherwise thumbnails will regenerate
          rel_file_path = self.preview_url.filepaths.url_cache_filepath_rel(media_id)
          media_store_path = os.path.join(self.media_store_path, rel_file_path)
          os.remove(media_store_path)
  
          # Move cached thumbnails into the storage provider
          os.makedirs(os.path.dirname(storage_provider_thumbnail_path), exist_ok=True)
          os.rename(media_store_thumbnail_path, storage_provider_thumbnail_path)
  
          channel = self.make_request(
              "GET",
              f"thumbnail/{host}/{media_id}?width=32&height=32&method=scale",
              shorthand=False,
              await_result=False,
          )
          self.pump()
          self.assertEqual(
              channel.code,
              404,
              "URL cache thumbnail was unexpectedly retrieved from a storage provider",
          )
  
      def test_cache_expiry(self) -> None:
          """Test that URL cache files and thumbnails are cleaned up properly on expiry."""
          self.preview_url.clock = MockClock()
  
          _host, media_id = self._download_image()
  
          file_path = self.preview_url.filepaths.url_cache_filepath(media_id)
          file_dirs = self.preview_url.filepaths.url_cache_filepath_dirs_to_delete(
              media_id
          )
          thumbnail_dir = self.preview_url.filepaths.url_cache_thumbnail_directory(
              media_id
          )
          thumbnail_dirs = self.preview_url.filepaths.url_cache_thumbnail_dirs_to_delete(
              media_id
          )
  
          self.assertTrue(os.path.isfile(file_path))
          self.assertTrue(os.path.isdir(thumbnail_dir))
  
          self.preview_url.clock.advance_time_msec(IMAGE_CACHE_EXPIRY_MS + 1)
          self.get_success(self.preview_url._expire_url_cache_data())
  
          for path in [file_path] + file_dirs + [thumbnail_dir] + thumbnail_dirs:
              self.assertFalse(
                  os.path.exists(path),
                  f"{os.path.relpath(path, self.media_store_path)} was not deleted",
              )
  
      @unittest.override_config({"url_preview_url_blacklist": [{"port": "*"}]})
      def test_blacklist_port(self) -> None:
          """Tests that blacklisting URLs with a port makes previewing such URLs
          fail with a 403 error and doesn't impact other previews.
          """
          self.lookups["matrix.org"] = [(IPv4Address, "10.1.2.3")]
  
          bad_url = quote("http://matrix.org:8888/foo")
          good_url = quote("http://matrix.org/foo")
  
          channel = self.make_request(
              "GET",
              "preview_url?url=" + bad_url,
              shorthand=False,
              await_result=False,
          )
          self.pump()
          self.assertEqual(channel.code, 403, channel.result)
  
          channel = self.make_request(
              "GET",
              "preview_url?url=" + good_url,
              shorthand=False,
              await_result=False,
          )
          self.pump()
  
          client = self.reactor.tcpClients[0][2].buildProtocol(None)
          server = AccumulatingProtocol()
          server.makeConnection(FakeTransport(client, self.reactor))
          client.makeConnection(FakeTransport(server, self.reactor))
          client.dataReceived(
              b"HTTP/1.0 200 OK\r\nContent-Length: %d\r\nContent-Type: text/html\r\n\r\n"
              % (len(self.end_content),)
              + self.end_content
          )
  
          self.pump()
          self.assertEqual(channel.code, 200)
  