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# SPDX-License-Identifier: GPL-3.0-or-later
# Data structure for querying URL patterns.
#
# This file is part of Hydrilla&Haketilo.
#
# Copyright (C) 2021, 2022 Wojtek Kosior
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see <https://www.gnu.org/licenses/>.
#
#
# I, Wojtek Kosior, thereby promise not to sue for violation of this
# file's license. Although I request that you do not make use of this
# code in a proprietary program, I am not going to enforce this in
# court.
"""
This module contains functions for deconstruction and construction of URLs and
Haketilo URL patterns.
Data structures for querying data using URL patterns are also defined there.
"""
# Enable using with Python 3.7.
from __future__ import annotations
import re
import urllib.parse as up
import typing as t
import dataclasses as dc
from immutables import Map
from .translations import smart_gettext as _
from .exceptions import HaketiloException
default_ports: t.Mapping[str, int] = Map(http=80, https=443, ftp=21)
ParsedUrlType = t.TypeVar('ParsedUrlType', bound='ParsedUrl')
@dc.dataclass(frozen=True, unsafe_hash=True, order=True)
class ParsedUrl:
"""...."""
orig_url: str # used in __hash__() and __lt__()
scheme: str = dc.field(hash=False, compare=False)
domain_labels: tuple[str, ...] = dc.field(hash=False, compare=False)
path_segments: tuple[str, ...] = dc.field(hash=False, compare=False)
query: str = dc.field(hash=False, compare=False)
has_trailing_slash: bool = dc.field(hash=False, compare=False)
port: t.Optional[int] = dc.field(hash=False, compare=False)
@property
def url_without_path(self) -> str:
"""...."""
scheme = self.scheme
netloc = '.'.join(reversed(self.domain_labels))
if self.port is not None and \
default_ports.get(scheme) != self.port:
netloc += f':{self.port}'
return f'{scheme}://{netloc}'
def reconstruct_url(self) -> str:
"""...."""
path = '/'.join(('', *self.path_segments))
if self.has_trailing_slash:
path += '/'
return self.url_without_path + path
def path_append(self: ParsedUrlType, *new_segments: str) -> ParsedUrlType:
"""...."""
new_url = self.reconstruct_url()
if not self.has_trailing_slash:
new_url += '/'
new_url += '/'.join(new_segments)
return dc.replace(
self,
orig_url = new_url,
path_segments = tuple((*self.path_segments, *new_segments)),
has_trailing_slash = False
)
ParsedPattern = t.NewType('ParsedPattern', ParsedUrl)
# # We sometimes need a dummy pattern that means "match everything".
# catchall_pattern = ParsedPattern(
# ParsedUrl(
# orig_url = '<dummy_catchall_url_pattern>'
# scheme = '<dummy_all-scheme>'
# domain_labels = ('***',)
# path_segments = ('***',)
# has_trailing_slash = False
# port = 0
# )
# )
# URLs with those schemes will be recognized but not all of them have to be
# actually supported by Hydrilla server and Haketilo proxy.
supported_schemes = 'http', 'https', 'ftp', 'file'
def _parse_pattern_or_url(
url: str,
orig_url: str,
is_pattern: bool = False
) -> ParsedUrl:
"""...."""
if not is_pattern:
assert orig_url == url
parse_result = up.urlparse(url)
# Verify the parsed URL is valid
has_hostname = parse_result.hostname is not None
if not parse_result.scheme or \
(parse_result.scheme == 'file' and parse_result.port is not None) or \
(parse_result.scheme == 'file' and has_hostname) or \
(parse_result.scheme != 'file' and not has_hostname):
if is_pattern:
msg = _('err.url_pattern_{}.bad').format(orig_url)
raise HaketiloException(msg)
else:
raise HaketiloException(_('err.url_{}.bad') .format(url))
# Verify the URL uses a known scheme and extract it.
scheme = parse_result.scheme
if parse_result.scheme not in supported_schemes:
if is_pattern:
msg = _('err.url_pattern_{}.bad_scheme').format(orig_url)
raise HaketiloException(msg)
else:
raise HaketiloException(_('err.url_{}.bad_scheme').format(url))
# Extract and keep information about special pattern schemas used.
if is_pattern and orig_url.startswith('http*:'):
if parse_result.port:
fmt = _('err.url_pattern_{}.special_scheme_port')
raise HaketiloException(fmt.format(orig_url))
# Extract URL's explicit port or deduce the port based on URL's protocol.
try:
explicit_port = parse_result.port
port_out_of_range = explicit_port == 0
except ValueError:
port_out_of_range = True
if port_out_of_range:
if is_pattern:
msg = _('err.url_pattern_{}.bad_port').format(orig_url)
raise HaketiloException(msg)
else:
raise HaketiloException(_('err.url_{}.bad_port').format(url))
port = explicit_port or default_ports.get(parse_result.scheme)
# Make URL's hostname into a list of labels in reverse order. E.g.
# 'https://a.bc..de.fg.com/h/i/' -> ['com', 'fg', 'de', 'bc', 'a']
hostname = parse_result.hostname or ''
domain_labels_with_empty = reversed(hostname.split('.'))
domain_labels = tuple(lbl for lbl in domain_labels_with_empty if lbl)
# Make URL's path into a list of segments. E.g.
# 'https://ab.cd/e//f/g/' -> ['e', 'f', 'g']
path_segments_with_empty = parse_result.path.split('/')
path_segments = tuple(sgmt for sgmt in path_segments_with_empty if sgmt)
# Record whether a trailing '/' is present in the URL.
has_trailing_slash = parse_result.path.endswith('/')
# Perform some additional sanity checks and return the result.
if is_pattern:
if parse_result.query:
msg = _('err.url_pattern_{}.has_query').format(orig_url)
raise HaketiloException(msg)
if parse_result.fragment:
msg = _('err.url_pattern_{}.has_frag').format(orig_url)
raise HaketiloException(msg)
query = parse_result.query
return ParsedUrl(
orig_url = orig_url,
scheme = scheme,
port = port,
domain_labels = domain_labels,
path_segments = path_segments,
query = query,
has_trailing_slash = has_trailing_slash
)
replace_scheme_regex = re.compile(r'^[^:]*')
def parse_pattern(url_pattern: str) -> t.Iterator[ParsedPattern]:
"""...."""
if url_pattern.startswith('http*:'):
patterns = [
replace_scheme_regex.sub('http', url_pattern),
replace_scheme_regex.sub('https', url_pattern)
]
else:
patterns = [url_pattern]
for pat in patterns:
yield ParsedPattern(
_parse_pattern_or_url(pat, url_pattern, True)
)
def parse_url(url: str) -> ParsedUrl:
"""...."""
return _parse_pattern_or_url(url, url)
def normalize_pattern(url_pattern: str) -> str:
parsed = next(parse_pattern(url_pattern))
reconstructed = parsed.reconstruct_url()
if url_pattern.startswith('http*'):
reconstructed = replace_scheme_regex.sub('http*', reconstructed)
return reconstructed
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