import html
import re
from typing import Callable, Optional
from urllib.parse import urlparse, urlunparse, quote, unquote # noqa: F401
from .utils import ESCAPABLE
# TODO below we port the use of the JS packages:
# var mdurl = require('mdurl')
# var punycode = require('punycode')
#
# e.g. mdurl: parsed = mdurl.parse(url, True)
#
# but need to check these fixes from https://www.npmjs.com/package/mdurl:
#
# Parse url string. Similar to node's url.parse,
# but without any normalizations and query string parse.
# url - input url (string)
# slashesDenoteHost - if url starts with //, expect a hostname after it. Optional, false.
# Difference with node's url:
# No leading slash in paths, e.g. in url.parse('http://foo?bar') pathname is ``, not /
# Backslashes are not replaced with slashes, so http:\\example.org\ is treated like a relative path
# Trailing colon is treated like a part of the path, i.e. in http://example.org:foo pathname is :foo
# Nothing is URL-encoded in the resulting object,
# (in joyent/node some chars in auth and paths are encoded)
# url.parse() does not have parseQueryString argument
# Removed extraneous result properties: host, path, query, etc.,
# which can be constructed using other parts of the url.
# ################# Copied from Commonmark.py #################
ENTITY = "&(?:#x[a-f0-9]{1,6}|#[0-9]{1,7}|[a-z][a-z0-9]{1,31});"
reBackslashOrAmp = re.compile(r"[\\&]")
reEntityOrEscapedChar = re.compile(
"\\\\" + "[" + ESCAPABLE + "]|" + ENTITY, re.IGNORECASE
)
[docs]def unescape_char(s: str) -> str:
if s[0] == "\\":
return s[1]
else:
return html.unescape(s)
[docs]def unescape_string(s: str) -> str:
"""Replace entities and backslash escapes with literal characters."""
if re.search(reBackslashOrAmp, s):
return re.sub(reEntityOrEscapedChar, lambda m: unescape_char(m.group()), s)
else:
return s
[docs]def normalize_uri(uri: str) -> str:
return quote(uri, safe="/@:+?=&()%#*,")
##################
RECODE_HOSTNAME_FOR = ("http", "https", "mailto")
[docs]def unescape_normalize_uri(x: str) -> str:
return normalize_uri(unescape_string(x))
[docs]def normalizeLink(url: str) -> str:
"""Normalize destination URLs in links
::
[label]: destination 'title'
^^^^^^^^^^^
"""
(scheme, netloc, path, params, query, fragment) = urlparse(url)
if scheme in RECODE_HOSTNAME_FOR:
url = urlunparse(
(
scheme,
unescape_normalize_uri(netloc),
normalize_uri(path),
unescape_normalize_uri(params),
normalize_uri(query),
unescape_normalize_uri(fragment),
)
)
else:
url = unescape_normalize_uri(url)
return url
# TODO the selective encoding below should probably be done here,
# something like:
# url_check = urllib.parse.urlparse(destination)
# if url_check.scheme in RECODE_HOSTNAME_FOR: ...
# parsed = urlparse(url)
# if parsed.hostname:
# # Encode hostnames in urls like:
# # `http:#host/`, `https:#host/`, `mailto:user@host`, `#host/`
# #
# # We don't encode unknown schemas, because it's likely that we encode
# # something we shouldn't (e.g. `skype:name` treated as `skype:host`)
# #
# if (not parsed.scheme) or parsed.scheme in RECODE_HOSTNAME_FOR:
# try:
# parsed.hostname = punycode.toASCII(parsed.hostname)
# except Exception:
# pass
# return quote(urlunparse(parsed))
[docs]def unescape_unquote(x: str) -> str:
return unquote(unescape_string(x))
[docs]def normalizeLinkText(link: str) -> str:
"""Normalize autolink content
::
<destination>
~~~~~~~~~~~
"""
(scheme, netloc, path, params, query, fragment) = urlparse(link)
if scheme in RECODE_HOSTNAME_FOR:
url = urlunparse(
(
scheme,
unescape_unquote(netloc),
unquote(path),
unescape_unquote(params),
unquote(query),
unescape_unquote(fragment),
)
)
else:
url = unescape_unquote(link)
return url
# TODO the selective encoding below should probably be done here,
# something like:
# url_check = urllib.parse.urlparse(destination)
# if url_check.scheme in RECODE_HOSTNAME_FOR: ...
# parsed = urlparse(url)
# if parsed.hostname:
# # Encode hostnames in urls like:
# # `http:#host/`, `https:#host/`, `mailto:user@host`, `#host/`
# #
# # We don't encode unknown schemas, because it's likely that we encode
# # something we shouldn't (e.g. `skype:name` treated as `skype:host`)
# #
# if (not parsed.protocol) or parsed.protocol in RECODE_HOSTNAME_FOR:
# try:
# parsed.hostname = punycode.toUnicode(parsed.hostname)
# except Exception:
# pass
# return unquote(urlunparse(parsed))
BAD_PROTO_RE = re.compile(r"^(vbscript|javascript|file|data):")
GOOD_DATA_RE = re.compile(r"^data:image\/(gif|png|jpeg|webp);")
[docs]def validateLink(url: str, validator: Optional[Callable] = None) -> bool:
"""Validate URL link is allowed in output.
This validator can prohibit more than really needed to prevent XSS.
It's a tradeoff to keep code simple and to be secure by default.
Note: url should be normalized at this point, and existing entities decoded.
"""
if validator is not None:
return validator(url)
url = url.strip().lower()
return bool(GOOD_DATA_RE.search(url)) if BAD_PROTO_RE.search(url) else True