Return back audio url decoder; Refactor audio url decoder

Author: python273

vk_api/audio.py

@@ -3,6 +3,7 @@
 
 from bs4 import BeautifulSoup
 
+from .audio_url_decoder import decode_audio_url
 from .exceptions import AccessDenied
 
 RE_AUDIO = re.compile(r'audio\d+_\d+_audios\d+')
@@ -94,6 +95,9 @@ def scrap_data(html):
         artist = ai_artist[0].text
         link = audio.select('.ai_body')[0].input['value']
 
+        if 'audio_api_unavailable' in link:
+            link = decode_audio_url(link)
+
         tracks.append({
             'artist': artist,
             'title': audio.select('.ai_title')[0].text,

vk_api/audio_url_decoder.py

@@ -0,0 +1,75 @@
+# -*- coding: utf-8 -*-
+
+VK_STR = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMN0PQRSTUVWXYZO123456789+/="
+
+
+def decode_audio_url(string):
+    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:
+        cmd, *arg = op_data.split('\x0b')
+
+        if cmd == 'v':
+            tstr = tstr[::-1]
+
+        elif cmd == 'r':
+            tstr = vk_r(tstr, arg[0])
+
+        elif cmd == 'x':
+            tstr = vk_xor(tstr, arg[0])
+
+    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)