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78 lines
2.4 KiB
Python
78 lines
2.4 KiB
Python
# -*- coding: utf-8 -*-
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# Copyright 2015 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 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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def bypass_ddos_protection(session, url):
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"""Prepare a requests.session to access 'url' behind Cloudflare protection"""
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session.headers["Referer"] = url
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page = session.get(url).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(url, page)
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time.sleep(4)
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session.get(urllib.parse.urljoin(url, "/cdn-cgi/l/chk_jschl"), 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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data, pos = text.extract_all(page, (
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('var' , 'var t,r,a,f, ', '='),
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('key' , '"', '"'),
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('expr', ':', '}')
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))
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solution = evaluate_expression(data["expr"])
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variable = "{}.{}".format(data["var"], data["key"])
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vlength = len(variable)
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expressions = text.extract(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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func = operator_functions[expr[vlength]]
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value = evaluate_expression(expr[vlength+2:])
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solution = func(solution, value)
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elif expr.startswith("a.value"):
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return solution + len(urllib.parse.urlparse(url).netloc)
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def evaluate_expression(expr):
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"""Evaluate a Javascript expression for the challange and return its value"""
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stack = []
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ranges = []
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value = ""
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for index, char in enumerate(expr):
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if char == "(":
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stack.append(index+1)
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elif char == ")":
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begin = stack.pop()
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if stack:
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ranges.append((begin, index))
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for subexpr in [expr[begin:end] for begin, end in ranges] or (expr,):
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num = 0
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for part in subexpr.split("[]"):
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num += expression_values[part]
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value += str(num)
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return int(value)
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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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