first commit

vk_api/audio_url_decoder.py

@@ -0,0 +1,141 @@
+# -*- coding: utf-8 -*-
+from .exceptions import VkAudioUrlDecodeError
+
+VK_STR = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMN0PQRSTUVWXYZO123456789+/="
+
+
+def splice(l, a, b, c):
+    """ JS's Array.prototype.splice
+
+    var x = [1, 2, 3],
+        y = x.splice(0, 2, 1337);
+
+    eq
+
+    x = [1, 2, 3]
+    x, y = splice(x, 0, 2, 1337)
+    """
+
+    return l[:a] + [c] + l[a + b:], l[a:a + b]
+
+
+def decode_audio_url(string, user_id):
+    vals = string.split("?extra=", 1)[1].split("#")
+
+    tstr = vk_o(vals[0])
+    ops_list = vk_o(vals[1]).split('\x09')[::-1]
+
+    for op_data in ops_list:
+
+        split_op_data = op_data.split('\x0b')
+        cmd = split_op_data[0]
+        if len(split_op_data) > 1:
+            arg = split_op_data[1]
+        else:
+            arg = None
+
+        if cmd == 'v':
+            tstr = tstr[::-1]
+
+        elif cmd == 'r':
+            tstr = vk_r(tstr, arg)
+
+        elif cmd == 'x':
+            tstr = vk_xor(tstr, arg)
+        elif cmd == 's':
+            tstr = vk_s(tstr, arg)
+        elif cmd == 'i':
+            tstr = vk_i(tstr, arg, user_id)
+        else:
+            raise VkAudioUrlDecodeError(
+                'Unknown decode cmd: "{}"; Please send bugreport'.format(cmd)
+            )
+
+    return tstr
+
+
+def vk_o(string):
+    result = []
+    index2 = 0
+
+    for s in string:
+        sym_index = VK_STR.find(s)
+
+        if sym_index != -1:
+            if index2 % 4 != 0:
+                i = (i << 6) + sym_index
+            else:
+                i = sym_index
+
+            if index2 % 4 != 0:
+                index2 += 1
+                shift = -2 * index2 & 6
+                result += [chr(0xFF & (i >> shift))]
+            else:
+                index2 += 1
+
+    return ''.join(result)
+
+
+def vk_r(string, i):
+    vk_str2 = VK_STR + VK_STR
+    vk_str2_len = len(vk_str2)
+
+    result = []
+
+    for s in string:
+        index = vk_str2.find(s)
+
+        if index != -1:
+            offset = index - int(i)
+
+            if offset < 0:
+                offset += vk_str2_len
+
+            result += [vk_str2[offset]]
+        else:
+            result += [s]
+
+    return ''.join(result)
+
+
+def vk_xor(string, i):
+    xor_val = ord(i[0])
+
+    return ''.join(chr(ord(s) ^ xor_val) for s in string)
+
+
+def vk_s_child(t, e):
+    i = len(t)
+
+    if not i:
+        return []
+
+    o = []
+    e = int(e)
+
+    for a in range(i - 1, -1, -1):
+        e = (i * (a + 1) ^ e + a) % i
+        o.append(e)
+
+    return o[::-1]
+
+
+def vk_s(t, e):
+    i = len(t)
+
+    if not i:
+        return t
+
+    o = vk_s_child(t, e)
+    t = list(t)
+
+    for a in range(1, i):
+        t, y = splice(t, o[i - 1 - a], 1, t[a])
+        t[a] = y[0]
+
+    return ''.join(t)
+
+
+def vk_i(t, e, user_id):
+    return vk_s(t, int(e) ^ user_id)