From 822527a2ceb70bb7b457153f42b163f0c1b04afb Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Mike=20F=C3=A4hrmann?= <mike_faehrmann@web.de>
Date: Sat, 7 Nov 2015 02:30:08 +0100
Subject: [PATCH] module to bypass cloudflare protection

---
 gallery_dl/cloudflare.py | 72 ++++++++++++++++++++++++++++++++++++++++
 1 file changed, 72 insertions(+)
 create mode 100644 gallery_dl/cloudflare.py

diff --git a/gallery_dl/cloudflare.py b/gallery_dl/cloudflare.py
new file mode 100644
index 00000000..0e92d2fa
--- /dev/null
+++ b/gallery_dl/cloudflare.py
@@ -0,0 +1,72 @@
+# -*- coding: utf-8 -*-
+
+# Copyright 2015 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.
+
+import time
+import operator
+from urllib.parse import urljoin
+from . import text
+
+def bypass_ddos_protection(session, url):
+    session.headers["Referer"] = url
+    page = session.get(url).text
+    params = text.extract_all(page, (
+        ('jschl_vc', 'name="jschl_vc" value="', '"'),
+        ('pass'    , 'name="pass" value="', '"'),
+    ))[0]
+    params["jschl_answer"] = solve_jschl(page)
+    time.sleep(4)
+    session.get(urljoin(url, "/cdn-cgi/l/chk_jschl"), params=params)
+
+def solve_jschl(page):
+    data, pos = text.extract_all(page, (
+        ('var' , 'var t,r,a,f, ', '='),
+        ('key' , '"', '"'),
+        ('expr', ':', '}')
+    ))
+    solution = evaluate_js_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_js_expression(expr[vlength+2:])
+            solution = func(solution, value)
+        elif expr.startswith("a.value"):
+            return solution + len("kissmanga.com")
+
+def evaluate_js_expression(expr):
+    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,
+}