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Allow configuration of the oEmbed URLs. (#10714)

Browse Source 
This adds configuration options (under an `oembed` section) to
configure which URLs are matched to use oEmbed for URL
previews.
This commit is contained in:
Patrick Cloke 2021-08-31 18:37:07 -04:00 committed by GitHub
parent 287918e2d4
commit e2481dbe93
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8 changed files with 458 additions and 247 deletions
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1
changelog.d/10714.feature Normal file
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@ -0,0 +1 @@
Allow configuration of the oEmbed URLs used for URL previews.

21
docs/sample_config.yaml
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@ -1075,6 +1075,27 @@ url_preview_accept_language:
# - en
# oEmbed allows for easier embedding content from a website. It can be
# used for generating URLs previews of services which support it.
#
oembed:
# A default list of oEmbed providers is included with Synapse.
#
# Uncomment the following to disable using these default oEmbed URLs.
# Defaults to 'false'.
#
#disable_default_providers: true
# Additional files with oEmbed configuration (each should be in the
# form of providers.json).
#
# By default, this list is empty (so only the default providers.json
# is used).
#
#additional_providers:
# - oembed/my_providers.json
## Captcha ##
# See docs/CAPTCHA_SETUP.md for full details of configuring this.

2
synapse/config/homeserver.py
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@ -30,6 +30,7 @@ from .key import KeyConfig
from .logger import LoggingConfig
from .metrics import MetricsConfig
from .modules import ModulesConfig
from .oembed import OembedConfig
from .oidc import OIDCConfig
from .password_auth_providers import PasswordAuthProviderConfig
from .push import PushConfig
@ -65,6 +66,7 @@ class HomeServerConfig(RootConfig):
LoggingConfig,
RatelimitConfig,
ContentRepositoryConfig,
OembedConfig,
CaptchaConfig,
VoipConfig,
RegistrationConfig,

180
synapse/config/oembed.py Normal file
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@ -0,0 +1,180 @@
# 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 json
import re
from typing import Any, Dict, Iterable, List, Pattern
from urllib import parse as urlparse
import attr
import pkg_resources
from synapse.types import JsonDict
from ._base import Config, ConfigError
from ._util import validate_config
@attr.s(slots=True, frozen=True, auto_attribs=True)
class OEmbedEndpointConfig:
# The API endpoint to fetch.
api_endpoint: str
# The patterns to match.
url_patterns: List[Pattern]
class OembedConfig(Config):
"""oEmbed Configuration"""
section = "oembed"
def read_config(self, config, **kwargs):
oembed_config: Dict[str, Any] = config.get("oembed") or {}
# A list of patterns which will be used.
self.oembed_patterns: List[OEmbedEndpointConfig] = list(
self._parse_and_validate_providers(oembed_config)
)
def _parse_and_validate_providers(
self, oembed_config: dict
) -> Iterable[OEmbedEndpointConfig]:
"""Extract and parse the oEmbed providers from the given JSON file.
Returns a generator which yields the OidcProviderConfig objects
"""
# Whether to use the packaged providers.json file.
if not oembed_config.get("disable_default_providers") or False:
providers = json.load(
pkg_resources.resource_stream("synapse", "res/providers.json")
)
yield from self._parse_and_validate_provider(
providers, config_path=("oembed",)
)
# The JSON files which includes additional provider information.
for i, file in enumerate(oembed_config.get("additional_providers") or []):
# TODO Error checking.
with open(file) as f:
providers = json.load(f)
yield from self._parse_and_validate_provider(
providers,
config_path=(
"oembed",
"additional_providers",
f"<item {i}>",
),
)
def _parse_and_validate_provider(
self, providers: List[JsonDict], config_path: Iterable[str]
) -> Iterable[OEmbedEndpointConfig]:
# Ensure it is the proper form.
validate_config(
_OEMBED_PROVIDER_SCHEMA,
providers,
config_path=config_path,
)
# Parse it and yield each result.
for provider in providers:
# Each provider might have multiple API endpoints, each which
# might have multiple patterns to match.
for endpoint in provider["endpoints"]:
api_endpoint = endpoint["url"]
patterns = [
self._glob_to_pattern(glob, config_path)
for glob in endpoint["schemes"]
]
yield OEmbedEndpointConfig(api_endpoint, patterns)
def _glob_to_pattern(self, glob: str, config_path: Iterable[str]) -> Pattern:
"""
Convert the glob into a sane regular expression to match against. The
rules followed will be slightly different for the domain portion vs.
the rest.
1. The scheme must be one of HTTP / HTTPS (and have no globs).
2. The domain can have globs, but we limit it to characters that can
reasonably be a domain part.
TODO: This does not attempt to handle Unicode domain names.
TODO: The domain should not allow wildcard TLDs.
3. Other parts allow a glob to be any one, or more, characters.
"""
results = urlparse.urlparse(glob)
# Ensure the scheme does not have wildcards (and is a sane scheme).
if results.scheme not in {"http", "https"}:
raise ConfigError(f"Insecure oEmbed scheme: {results.scheme}", config_path)
pattern = urlparse.urlunparse(
[
results.scheme,
re.escape(results.netloc).replace("\\*", "[a-zA-Z0-9_-]+"),
]
+ [re.escape(part).replace("\\*", ".+") for part in results[2:]]
)
return re.compile(pattern)
def generate_config_section(self, **kwargs):
return """\
# oEmbed allows for easier embedding content from a website. It can be
# used for generating URLs previews of services which support it.
#
oembed:
# A default list of oEmbed providers is included with Synapse.
#
# Uncomment the following to disable using these default oEmbed URLs.
# Defaults to 'false'.
#
#disable_default_providers: true
# Additional files with oEmbed configuration (each should be in the
# form of providers.json).
#
# By default, this list is empty (so only the default providers.json
# is used).
#
#additional_providers:
# - oembed/my_providers.json
"""
_OEMBED_PROVIDER_SCHEMA = {
"type": "array",
"items": {
"type": "object",
"properties": {
"provider_name": {"type": "string"},
"provider_url": {"type": "string"},
"endpoints": {
"type": "array",
"items": {
"type": "object",
"properties": {
"schemes": {
"type": "array",
"items": {"type": "string"},
},
"url": {"type": "string"},
"formats": {"type": "array", "items": {"type": "string"}},
"discovery": {"type": "boolean"},
},
"required": ["schemes", "url"],
},
},
},
"required": ["provider_name", "provider_url", "endpoints"],
},
}

17
synapse/res/providers.json Normal file
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@ -0,0 +1,17 @@
[
{
"provider_name": "Twitter",
"provider_url": "http://www.twitter.com/",
"endpoints": [
{
"schemes": [
"https://twitter.com/*/status/*",
"https://*.twitter.com/*/status/*",
"https://twitter.com/*/moments/*",
"https://*.twitter.com/*/moments/*"
],
"url": "https://publish.twitter.com/oembed"
}
]
}
]

135
synapse/rest/media/v1/oembed.py Normal file
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@ -0,0 +1,135 @@
# 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 logging
from typing import TYPE_CHECKING, Optional
import attr
from synapse.http.client import SimpleHttpClient
if TYPE_CHECKING:
from synapse.server import HomeServer
logger = logging.getLogger(__name__)
@attr.s(slots=True, auto_attribs=True)
class OEmbedResult:
# Either HTML content or URL must be provided.
html: Optional[str]
url: Optional[str]
title: Optional[str]
# Number of seconds to cache the content.
cache_age: int
class OEmbedError(Exception):
"""An error occurred processing the oEmbed object."""
class OEmbedProvider:
"""
A helper for accessing oEmbed content.
It can be used to check if a URL should be accessed via oEmbed and for
requesting/parsing oEmbed content.
"""
def __init__(self, hs: "HomeServer", client: SimpleHttpClient):
self._oembed_patterns = {}
for oembed_endpoint in hs.config.oembed.oembed_patterns:
for pattern in oembed_endpoint.url_patterns:
self._oembed_patterns[pattern] = oembed_endpoint.api_endpoint
self._client = client
def get_oembed_url(self, url: str) -> Optional[str]:
"""
Check whether the URL should be downloaded as oEmbed content instead.
Args:
url: The URL to check.
Returns:
A URL to use instead or None if the original URL should be used.
"""
for url_pattern, endpoint in self._oembed_patterns.items():
if url_pattern.fullmatch(url):
return endpoint
# No match.
return None
async def get_oembed_content(self, endpoint: str, url: str) -> OEmbedResult:
"""
Request content from an oEmbed endpoint.
Args:
endpoint: The oEmbed API endpoint.
url: The URL to pass to the API.
Returns:
An object representing the metadata returned.
Raises:
OEmbedError if fetching or parsing of the oEmbed information fails.
"""
try:
logger.debug("Trying to get oEmbed content for url '%s'", url)
result = await self._client.get_json(
endpoint,
# TODO Specify max height / width.
# Note that only the JSON format is supported.
args={"url": url},
)
# Ensure there's a version of 1.0.
if result.get("version") != "1.0":
raise OEmbedError("Invalid version: %s" % (result.get("version"),))
oembed_type = result.get("type")
# Ensure the cache age is None or an int.
cache_age = result.get("cache_age")
if cache_age:
cache_age = int(cache_age)
oembed_result = OEmbedResult(None, None, result.get("title"), cache_age)
# HTML content.
if oembed_type == "rich":
oembed_result.html = result.get("html")
return oembed_result
if oembed_type == "photo":
oembed_result.url = result.get("url")
return oembed_result
# TODO Handle link and video types.
if "thumbnail_url" in result:
oembed_result.url = result.get("thumbnail_url")
return oembed_result
raise OEmbedError("Incompatible oEmbed information.")
except OEmbedError as e:
# Trap OEmbedErrors first so we can directly re-raise them.
logger.warning("Error parsing oEmbed metadata from %s: %r", url, e)
raise
except Exception as e:
# Trap any exception and let the code follow as usual.
# FIXME: pass through 404s and other error messages nicely
logger.warning("Error downloading oEmbed metadata from %s: %r", url, e)
raise OEmbedError() from e

147
synapse/rest/media/v1/preview_url_resource.py
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@ -25,8 +25,6 @@ import traceback
from typing import TYPE_CHECKING, Any, Dict, Generator, Iterable, Optional, Union
from urllib import parse as urlparse
import attr
from twisted.internet.error import DNSLookupError
from twisted.web.server import Request
@ -43,6 +41,7 @@ from synapse.logging.context import make_deferred_yieldable, run_in_background
from synapse.metrics.background_process_metrics import run_as_background_process
from synapse.rest.media.v1._base import get_filename_from_headers
from synapse.rest.media.v1.media_storage import MediaStorage
from synapse.rest.media.v1.oembed import OEmbedError, OEmbedProvider
from synapse.util import json_encoder
from synapse.util.async_helpers import ObservableDeferred
from synapse.util.caches.expiringcache import ExpiringCache
@ -71,63 +70,6 @@ OG_TAG_VALUE_MAXLEN = 1000
ONE_HOUR = 60 * 60 * 1000
# A map of globs to API endpoints.
_oembed_globs = {
# Twitter.
"https://publish.twitter.com/oembed": [
"https://twitter.com/*/status/*",
"https://*.twitter.com/*/status/*",
"https://twitter.com/*/moments/*",
"https://*.twitter.com/*/moments/*",
# Include the HTTP versions too.
"http://twitter.com/*/status/*",
"http://*.twitter.com/*/status/*",
"http://twitter.com/*/moments/*",
"http://*.twitter.com/*/moments/*",
],
}
# Convert the globs to regular expressions.
_oembed_patterns = {}
for endpoint, globs in _oembed_globs.items():
for glob in globs:
# Convert the glob into a sane regular expression to match against. The
# rules followed will be slightly different for the domain portion vs.
# the rest.
#
# 1. The scheme must be one of HTTP / HTTPS (and have no globs).
# 2. The domain can have globs, but we limit it to characters that can
# reasonably be a domain part.
# TODO: This does not attempt to handle Unicode domain names.
# 3. Other parts allow a glob to be any one, or more, characters.
results = urlparse.urlparse(glob)
# Ensure the scheme does not have wildcards (and is a sane scheme).
if results.scheme not in {"http", "https"}:
raise ValueError("Insecure oEmbed glob scheme: %s" % (results.scheme,))
pattern = urlparse.urlunparse(
[
results.scheme,
re.escape(results.netloc).replace("\\*", "[a-zA-Z0-9_-]+"),
]
+ [re.escape(part).replace("\\*", ".+") for part in results[2:]]
)
_oembed_patterns[re.compile(pattern)] = endpoint
@attr.s(slots=True)
class OEmbedResult:
# Either HTML content or URL must be provided.
html = attr.ib(type=Optional[str])
url = attr.ib(type=Optional[str])
title = attr.ib(type=Optional[str])
# Number of seconds to cache the content.
cache_age = attr.ib(type=int)
class OEmbedError(Exception):
"""An error occurred processing the oEmbed object."""
class PreviewUrlResource(DirectServeJsonResource):
isLeaf = True
@ -157,6 +99,8 @@ class PreviewUrlResource(DirectServeJsonResource):
self.primary_base_path = media_repo.primary_base_path
self.media_storage = media_storage
self._oembed = OEmbedProvider(hs, self.client)
# We run the background jobs if we're the instance specified (or no
# instance is specified, where we assume there is only one instance
# serving media).
@ -367,87 +311,6 @@ class PreviewUrlResource(DirectServeJsonResource):
return jsonog.encode("utf8")
def _get_oembed_url(self, url: str) -> Optional[str]:
"""
Check whether the URL should be downloaded as oEmbed content instead.
Args:
url: The URL to check.
Returns:
A URL to use instead or None if the original URL should be used.
"""
for url_pattern, endpoint in _oembed_patterns.items():
if url_pattern.fullmatch(url):
return endpoint
# No match.
return None
async def _get_oembed_content(self, endpoint: str, url: str) -> OEmbedResult:
"""
Request content from an oEmbed endpoint.
Args:
endpoint: The oEmbed API endpoint.
url: The URL to pass to the API.
Returns:
An object representing the metadata returned.
Raises:
OEmbedError if fetching or parsing of the oEmbed information fails.
"""
try:
logger.debug("Trying to get oEmbed content for url '%s'", url)
result = await self.client.get_json(
endpoint,
# TODO Specify max height / width.
# Note that only the JSON format is supported.
args={"url": url},
)
# Ensure there's a version of 1.0.
if result.get("version") != "1.0":
raise OEmbedError("Invalid version: %s" % (result.get("version"),))
oembed_type = result.get("type")
# Ensure the cache age is None or an int.
cache_age = result.get("cache_age")
if cache_age:
cache_age = int(cache_age)
oembed_result = OEmbedResult(None, None, result.get("title"), cache_age)
# HTML content.
if oembed_type == "rich":
oembed_result.html = result.get("html")
return oembed_result
if oembed_type == "photo":
oembed_result.url = result.get("url")
return oembed_result
# TODO Handle link and video types.
if "thumbnail_url" in result:
oembed_result.url = result.get("thumbnail_url")
return oembed_result
raise OEmbedError("Incompatible oEmbed information.")
except OEmbedError as e:
# Trap OEmbedErrors first so we can directly re-raise them.
logger.warning("Error parsing oEmbed metadata from %s: %r", url, e)
raise
except Exception as e:
# Trap any exception and let the code follow as usual.
# FIXME: pass through 404s and other error messages nicely
logger.warning("Error downloading oEmbed metadata from %s: %r", url, e)
raise OEmbedError() from e
async def _download_url(self, url: str, user: str) -> Dict[str, Any]:
# TODO: we should probably honour robots.txt... except in practice
# we're most likely being explicitly triggered by a human rather than a
@ -459,11 +322,11 @@ class PreviewUrlResource(DirectServeJsonResource):
# If this URL can be accessed via oEmbed, use that instead.
url_to_download: Optional[str] = url
oembed_url = self._get_oembed_url(url)
oembed_url = self._oembed.get_oembed_url(url)
if oembed_url:
# The result might be a new URL to download, or it might be HTML content.
try:
oembed_result = await self._get_oembed_content(oembed_url, url)
oembed_result = await self._oembed.get_oembed_content(oembed_url, url)
if oembed_result.url:
url_to_download = oembed_result.url
elif oembed_result.html:

38
tests/rest/media/v1/test_url_preview.py
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@ -14,13 +14,14 @@
import json
import os
import re
from unittest.mock import patch
from twisted.internet._resolver import HostResolution
from twisted.internet.address import IPv4Address, IPv6Address
from twisted.internet.error import DNSLookupError
from twisted.test.proto_helpers import AccumulatingProtocol
from synapse.config.oembed import OEmbedEndpointConfig
from tests import unittest
from tests.server import FakeTransport
@ -81,6 +82,19 @@ class URLPreviewTests(unittest.HomeserverTestCase):
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/.+"),
],
)
]
return hs
def prepare(self, reactor, clock, hs):
@ -544,17 +558,6 @@ class URLPreviewTests(unittest.HomeserverTestCase):
def test_oembed_photo(self):
"""Test an oEmbed endpoint which returns a 'photo' type which redirects the preview to a new URL."""
# Route the HTTP version to an HTTP endpoint so that the tests work.
with patch.dict(
"synapse.rest.media.v1.preview_url_resource._oembed_patterns",
{
re.compile(
r"http://twitter\.com/.+/status/.+"
): "http://publish.twitter.com/oembed",
},
clear=True,
):
self.lookups["publish.twitter.com"] = [(IPv4Address, "10.1.2.3")]
self.lookups["cdn.twitter.com"] = [(IPv4Address, "10.1.2.3")]
@ -617,17 +620,6 @@ class URLPreviewTests(unittest.HomeserverTestCase):
def test_oembed_rich(self):
"""Test an oEmbed endpoint which returns HTML content via the 'rich' type."""
# Route the HTTP version to an HTTP endpoint so that the tests work.
with patch.dict(
"synapse.rest.media.v1.preview_url_resource._oembed_patterns",
{
re.compile(
r"http://twitter\.com/.+/status/.+"
): "http://publish.twitter.com/oembed",
},
clear=True,
):
self.lookups["publish.twitter.com"] = [(IPv4Address, "10.1.2.3")]
result = {