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import html
from typing import Iterable, Optional
from urllib.parse import quote, urlparse
def escape_url(raw: str) -> str:
"""
Escape urls to prevent code injection craziness. (Hopefully.)
"""
return html.escape(quote(html.unescape(raw), safe="/#:()*?=%@+,&"))
def is_external_url(
reference: str,
known_url_schemes: Optional[Iterable[str]],
match_fragment: bool = False,
) -> bool:
"""Return if a reference should be recognised as an external URL.
URLs are of the format: scheme://netloc/path;parameters?query#fragment
This checks if there is a url scheme (e.g. 'https') and, if so,
if the scheme is is the list of known_url_schemes (if supplied).
:param known_url_schemes: e.g. ["http", "https", "mailto"]
If None, match all schemes
:param match_fragment: If True and a fragment found, then True will be returned,
irrespective of a scheme match
"""
url_check = urlparse(reference)
if known_url_schemes is not None:
scheme_known = url_check.scheme in known_url_schemes
else:
scheme_known = bool(url_check.scheme)
return scheme_known or (match_fragment and url_check.fragment != "")
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