mirror of
https://github.com/mikf/gallery-dl.git
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128 lines
3.7 KiB
Python
128 lines
3.7 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2015-2018 Mike Fährmann
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License version 2 as
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# published by the Free Software Foundation.
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"""Methods to access sites behind Cloudflare protection"""
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import re
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import time
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import operator
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import urllib.parse
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from . import text
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from .cache import cache
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def request_func(self, *args, **kwargs):
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cookies = _cookiecache(self.root)
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if cookies:
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self.session.cookies.update(cookies)
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response = self.session.get(*args, **kwargs)
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if response.status_code == 503:
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_cookiecache.invalidate(self.root)
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self.log.info("Solving Cloudflare challenge")
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response = solve_challenge(self.session, response)
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_cookiecache(self.root, self.session.cookies)
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return response
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def solve_challenge(session, response):
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session.headers["Referer"] = response.url
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page = response.text
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params = text.extract_all(page, (
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('jschl_vc', 'name="jschl_vc" value="', '"'),
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('pass' , 'name="pass" value="', '"'),
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))[0]
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params["jschl_answer"] = solve_jschl(response.url, page)
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time.sleep(4)
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url = text.urljoin(response.url, "/cdn-cgi/l/chk_jschl")
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return session.get(url, params=params)
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def solve_jschl(url, page):
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"""Solve challenge to get 'jschl_answer' value"""
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# build variable name
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# e.g. '...f, wqnVscP={"DERKbJk":+(...' --> wqnVscP.DERKbJk
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data, pos = text.extract_all(page, (
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('var' , ',f, ', '='),
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('key' , '"', '"'),
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('expr', ':', '}'),
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))
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variable = "{}.{}".format(data["var"], data["key"])
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vlength = len(variable)
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# evaluate the initial expression
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solution = evaluate_expression(data["expr"])
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# iterator over all remaining expressions
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# and combine their values in 'solution'
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expressions = text.extract(
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page, "'challenge-form');", "f.submit();", pos)[0]
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for expr in expressions.split(";")[1:]:
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if expr.startswith(variable):
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# select arithmetc function based on operator (+, -, *)
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func = operator_functions[expr[vlength]]
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# evaluate the rest of the expression
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value = evaluate_expression(expr[vlength+2:])
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# combine the expression value with our current solution
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solution = func(solution, value)
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elif expr.startswith("a.value"):
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# add length of the hostname, i.e. add 11 for 'example.org'
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solution += len(urllib.parse.urlsplit(url).netloc)
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if ".toFixed(" in expr:
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# trim the solution to 10 decimal places
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# and strip trailing zeros
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solution = "{:.10f}".format(solution).rstrip("0")
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return solution
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def evaluate_expression(expr, split_re=re.compile(r"\(+([^)]*)\)")):
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"""Evaluate a Javascript expression for the challenge"""
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if "/" in expr:
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# split the expression in numerator and denominator subexpressions,
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# evaluate them separately,
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# and return their fraction-result
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num, _, denom = expr.partition("/")
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return evaluate_expression(num) / evaluate_expression(denom)
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# iterate over all subexpressions,
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# evaluate them,
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# and accumulate their values in 'result'
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result = ""
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for subexpr in split_re.findall(expr):
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result += str(sum(
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expression_values[part]
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for part in subexpr.split("[]")
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))
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return int(result)
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operator_functions = {
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"+": operator.add,
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"-": operator.sub,
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"*": operator.mul,
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}
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expression_values = {
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"": 0,
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"+": 0,
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"!+": 1,
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"+!!": 1,
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}
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@cache(maxage=365*24*60*60, keyarg=0)
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def _cookiecache(key, item=None):
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return item
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