mirror of https://github.com/zulip/zulip.git
119 lines
4.3 KiB
Python
119 lines
4.3 KiB
Python
import re
|
|
from typing import Any, Callable, Dict, Match, Optional
|
|
|
|
import magic
|
|
import requests
|
|
from django.conf import settings
|
|
from django.utils.encoding import smart_text
|
|
|
|
from version import ZULIP_VERSION
|
|
from zerver.lib.cache import cache_with_key, get_cache_with_key, preview_url_cache_key
|
|
from zerver.lib.pysa import mark_sanitized
|
|
from zerver.lib.url_preview.oembed import get_oembed_data
|
|
from zerver.lib.url_preview.parsers import GenericParser, OpenGraphParser
|
|
|
|
# FIXME: Should we use a database cache or a memcached in production? What if
|
|
# opengraph data is changed for a site?
|
|
# Use an in-memory cache for development, to make it easy to develop this code
|
|
CACHE_NAME = "database" if not settings.DEVELOPMENT else "in-memory"
|
|
# Based on django.core.validators.URLValidator, with ftp support removed.
|
|
link_regex = re.compile(
|
|
r"^(?:http)s?://" # http:// or https://
|
|
r"(?:(?:[A-Z0-9](?:[A-Z0-9-]{0,61}[A-Z0-9])?\.)+(?:[A-Z]{2,6}\.?|[A-Z0-9-]{2,}\.?)|" # domain...
|
|
r"\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3})" # ...or ip
|
|
r"(?::\d+)?" # optional port
|
|
r"(?:/?|[/?]\S+)$",
|
|
re.IGNORECASE,
|
|
)
|
|
|
|
# Use Chrome User-Agent, since some sites refuse to work on old browsers
|
|
ZULIP_URL_PREVIEW_USER_AGENT = (
|
|
"Mozilla/5.0 (compatible; ZulipURLPreview/{version}; +{external_host})"
|
|
).format(version=ZULIP_VERSION, external_host=settings.ROOT_DOMAIN_URI)
|
|
|
|
# FIXME: This header and timeout are not used by pyoembed, when trying to autodiscover!
|
|
HEADERS = {"User-Agent": ZULIP_URL_PREVIEW_USER_AGENT}
|
|
TIMEOUT = 15
|
|
|
|
|
|
def is_link(url: str) -> Optional[Match[str]]:
|
|
return link_regex.match(smart_text(url))
|
|
|
|
|
|
def guess_mimetype_from_content(response: requests.Response) -> str:
|
|
mime_magic = magic.Magic(mime=True)
|
|
try:
|
|
content = next(response.iter_content(1000))
|
|
except StopIteration:
|
|
content = ""
|
|
return mime_magic.from_buffer(content)
|
|
|
|
|
|
def valid_content_type(url: str) -> bool:
|
|
try:
|
|
response = requests.get(url, stream=True, headers=HEADERS, timeout=TIMEOUT)
|
|
except requests.RequestException:
|
|
return False
|
|
|
|
if not response.ok:
|
|
return False
|
|
|
|
content_type = response.headers.get("content-type")
|
|
# Be accommodating of bad servers: assume content may be html if no content-type header
|
|
if not content_type or content_type.startswith("text/html"):
|
|
# Verify that the content is actually HTML if the server claims it is
|
|
content_type = guess_mimetype_from_content(response)
|
|
return content_type.startswith("text/html")
|
|
|
|
|
|
def catch_network_errors(func: Callable[..., Any]) -> Callable[..., Any]:
|
|
def wrapper(*args: Any, **kwargs: Any) -> Any:
|
|
try:
|
|
return func(*args, **kwargs)
|
|
except requests.exceptions.RequestException:
|
|
pass
|
|
|
|
return wrapper
|
|
|
|
|
|
@catch_network_errors
|
|
@cache_with_key(preview_url_cache_key, cache_name=CACHE_NAME, with_statsd_key="urlpreview_data")
|
|
def get_link_embed_data(
|
|
url: str, maxwidth: int = 640, maxheight: int = 480
|
|
) -> Optional[Dict[str, Any]]:
|
|
if not is_link(url):
|
|
return None
|
|
|
|
if not valid_content_type(url):
|
|
return None
|
|
|
|
# We are using two different mechanisms to get the embed data
|
|
# 1. Use OEmbed data, if found, for photo and video "type" sites
|
|
# 2. Otherwise, use a combination of Open Graph tags and Meta tags
|
|
data = get_oembed_data(url, maxwidth=maxwidth, maxheight=maxheight) or {}
|
|
if data.get("oembed"):
|
|
return data
|
|
|
|
response = requests.get(mark_sanitized(url), stream=True, headers=HEADERS, timeout=TIMEOUT)
|
|
if response.ok:
|
|
og_data = OpenGraphParser(
|
|
response.content, response.headers.get("Content-Type")
|
|
).extract_data()
|
|
for key in ["title", "description", "image"]:
|
|
if not data.get(key) and og_data.get(key):
|
|
data[key] = og_data[key]
|
|
|
|
generic_data = (
|
|
GenericParser(response.content, response.headers.get("Content-Type")).extract_data()
|
|
or {}
|
|
)
|
|
for key in ["title", "description", "image"]:
|
|
if not data.get(key) and generic_data.get(key):
|
|
data[key] = generic_data[key]
|
|
return data
|
|
|
|
|
|
@get_cache_with_key(preview_url_cache_key, cache_name=CACHE_NAME)
|
|
def link_embed_data_from_cache(url: str, maxwidth: int = 640, maxheight: int = 480) -> Any:
|
|
return
|