81 lines
2.5 KiB
Python
81 lines
2.5 KiB
Python
from __future__ import annotations
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from collections.abc import Callable
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from contextlib import suppress
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import re
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from urllib.parse import quote, unquote, urlparse, urlunparse # noqa: F401
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import mdurl
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from .. import _punycode
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RECODE_HOSTNAME_FOR = ("http:", "https:", "mailto:")
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def normalizeLink(url: str) -> str:
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"""Normalize destination URLs in links
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::
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[label]: destination 'title'
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^^^^^^^^^^^
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"""
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parsed = mdurl.parse(url, slashes_denote_host=True)
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# Encode hostnames in urls like:
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# `http://host/`, `https://host/`, `mailto:user@host`, `//host/`
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#
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# We don't encode unknown schemas, because it's likely that we encode
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# something we shouldn't (e.g. `skype:name` treated as `skype:host`)
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#
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if parsed.hostname and (
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not parsed.protocol or parsed.protocol in RECODE_HOSTNAME_FOR
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):
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with suppress(Exception):
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parsed = parsed._replace(hostname=_punycode.to_ascii(parsed.hostname))
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return mdurl.encode(mdurl.format(parsed))
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def normalizeLinkText(url: str) -> str:
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"""Normalize autolink content
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::
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<destination>
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~~~~~~~~~~~
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"""
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parsed = mdurl.parse(url, slashes_denote_host=True)
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# Encode hostnames in urls like:
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# `http://host/`, `https://host/`, `mailto:user@host`, `//host/`
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#
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# We don't encode unknown schemas, because it's likely that we encode
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# something we shouldn't (e.g. `skype:name` treated as `skype:host`)
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#
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if parsed.hostname and (
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not parsed.protocol or parsed.protocol in RECODE_HOSTNAME_FOR
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):
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with suppress(Exception):
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parsed = parsed._replace(hostname=_punycode.to_unicode(parsed.hostname))
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# add '%' to exclude list because of https://github.com/markdown-it/markdown-it/issues/720
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return mdurl.decode(mdurl.format(parsed), mdurl.DECODE_DEFAULT_CHARS + "%")
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BAD_PROTO_RE = re.compile(r"^(vbscript|javascript|file|data):")
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GOOD_DATA_RE = re.compile(r"^data:image\/(gif|png|jpeg|webp);")
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def validateLink(url: str, validator: Callable[[str], bool] | None = None) -> bool:
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"""Validate URL link is allowed in output.
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This validator can prohibit more than really needed to prevent XSS.
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It's a tradeoff to keep code simple and to be secure by default.
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Note: url should be normalized at this point, and existing entities decoded.
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"""
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if validator is not None:
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return validator(url)
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url = url.strip().lower()
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return bool(GOOD_DATA_RE.search(url)) if BAD_PROTO_RE.search(url) else True
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