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gallery-dl/gallery_dl/cloudflare.py
2018-01-11 18:49:19 +01:00

104 lines
2.9 KiB
Python

# -*- coding: utf-8 -*-
# Copyright 2015-2017 Mike Fährmann
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License version 2 as
# published by the Free Software Foundation.
"""Methods to access sites behind Cloudflare protection"""
import time
import operator
import urllib.parse
from . import text
from .cache import cache
def request_func(self, *args, **kwargs):
cookies = _cookiecache(self.root)
if cookies:
self.session.cookies.update(cookies)
response = self.session.get(*args, **kwargs)
if response.status_code == 503:
_cookiecache.invalidate(self.root)
self.log.debug(response.text)
self.log.info("Solving Cloudflare challenge")
response = solve_challenge(self.session, response)
_cookiecache(self.root, self.session.cookies)
return response
def solve_challenge(session, response):
session.headers["Referer"] = response.url
page = response.text
params = text.extract_all(page, (
('jschl_vc', 'name="jschl_vc" value="', '"'),
('pass' , 'name="pass" value="', '"'),
))[0]
params["jschl_answer"] = solve_jschl(response.url, page)
time.sleep(4)
url = urllib.parse.urljoin(response.url, "/cdn-cgi/l/chk_jschl")
return session.get(url, params=params)
def solve_jschl(url, page):
"""Solve challenge to get 'jschl_answer' value"""
data, pos = text.extract_all(page, (
('var' , ',f, ', '='),
('key' , '"', '"'),
('expr', ':', '}'),
))
solution = evaluate_expression(data["expr"])
variable = "{}.{}".format(data["var"], data["key"])
vlength = len(variable)
expressions = text.extract(
page, "'challenge-form');", "f.submit();", pos
)[0]
for expr in expressions.split(";")[1:]:
if expr.startswith(variable):
func = operator_functions[expr[vlength]]
value = evaluate_expression(expr[vlength+2:])
solution = func(solution, value)
elif expr.startswith("a.value"):
return solution + len(urllib.parse.urlsplit(url).netloc)
def evaluate_expression(expr):
"""Evaluate a Javascript expression for the challenge"""
stack = []
ranges = []
value = ""
for index, char in enumerate(expr):
if char == "(":
stack.append(index+1)
elif char == ")":
begin = stack.pop()
if stack:
ranges.append((begin, index))
for subexpr in [expr[begin:end] for begin, end in ranges] or (expr,):
num = 0
for part in subexpr.split("[]"):
num += expression_values[part]
value += str(num)
return int(value)
operator_functions = {
"+": operator.add,
"-": operator.sub,
"*": operator.mul,
}
expression_values = {
"": 0,
"+": 0,
"!+": 1,
"+!!": 1,
}
@cache(maxage=365*24*60*60, keyarg=0)
def _cookiecache(key, item=None):
return item