Create mega.py

tools/mega.py

@@ -0,0 +1,122 @@
+import os
+import re
+import json
+import codecs
+import random
+import base64
+import struct
+import shutil
+import requests
+import tempfile
+
+from Crypto.Cipher import AES
+from Crypto.Util import Counter
+
+def makebyte(x):
+    return codecs.latin_1_encode(x)[0]
+
+def a32_to_str(a):
+    return struct.pack('>%dI' % len(a), *a)
+
+def get_chunks(size):
+    p, s = 0, 0x20000
+
+    while p + s < size:
+        yield(p, s)
+        p += s
+
+        if s < 0x100000: s += 0x20000
+
+    yield(p, size - p)
+
+def aes_cbc_decrypt(data, key):
+    aes_cipher = AES.new(key, AES.MODE_CBC, makebyte('\0' * 16))
+    return aes_cipher.decrypt(data)
+
+def decrypt_attr(attr, key):
+    attr = codecs.latin_1_decode(aes_cbc_decrypt(attr, a32_to_str(key)))[0].rstrip('\0')
+    return json.loads(attr[4:]) if attr[:6] == 'MEGA{"' else False
+
+def _api_request(data):
+    sequence_num = random.randint(0, 0xFFFFFFFF)
+    params = {'id': sequence_num}
+    sequence_num += 1
+
+    if not isinstance(data, list): data = [data]
+    json_resp = json.loads(requests.post('{0}://g.api.{1}/cs'.format('https', 'mega.co.nz'), params=params, data=json.dumps(data), timeout=160).text)
+    if isinstance(json_resp, int): raise Exception(json_resp)
+
+    return json_resp[0]
+
+def base64_url_decode(data):
+    data += '=='[(2 - len(data) * 3) % 4:]
+
+    for search, replace in (('-', '+'), ('_', '/'), (',', '')):
+        data = data.replace(search, replace)
+
+    return base64.b64decode(data)
+
+def str_to_a32(b):
+    if isinstance(b, str): b = makebyte(b)
+    if len(b) % 4: b += b'\0' * (4 - len(b) % 4)
+    return struct.unpack('>%dI' % (len(b) / 4), b)
+
+def base64_to_a32(s):
+    return str_to_a32(base64_url_decode(s))
+
+def mega_download_file(file_handle, file_key, dest_path=None):
+    file_key = base64_to_a32(file_key)
+    file_data = _api_request({'a': 'g', 'g': 1, 'p': file_handle})
+
+    k = (file_key[0] ^ file_key[4], file_key[1] ^ file_key[5], file_key[2] ^ file_key[6], file_key[3] ^ file_key[7])
+    iv = file_key[4:6] + (0, 0)
+
+    if 'g' not in file_data: raise Exception
+
+    file_size = file_data['s']
+    attribs = decrypt_attr(base64_url_decode(file_data['at']), k)
+    input_file = requests.get(file_data['g'], stream=True).raw
+
+    temp_output_file = tempfile.NamedTemporaryFile(mode='w+b', prefix='megapy_', delete=False)
+    k_str = a32_to_str(k)
+    aes = AES.new(k_str, AES.MODE_CTR, counter=Counter.new(128, initial_value=((iv[0] << 32) + iv[1]) << 64))
+
+    mac_str = b'\0' * 16
+    mac_encryptor = AES.new(k_str, AES.MODE_CBC, mac_str)
+    iv_str = a32_to_str([iv[0], iv[1], iv[0], iv[1]])
+
+    for _, chunk_size in get_chunks(file_size):
+        chunk = aes.decrypt(input_file.read(chunk_size))
+        temp_output_file.write(chunk)
+
+        encryptor = AES.new(k_str, AES.MODE_CBC, iv_str)
+
+        for i in range(0, len(chunk) - 16, 16):
+            block = chunk[i:i + 16]
+            encryptor.encrypt(block)
+
+        i = (i + 16) if file_size > 16 else 0
+        block = chunk[i:i + 16]
+        if len(block) % 16: block += b'\0' * (16 - (len(block) % 16))
+
+        mac_str = mac_encryptor.encrypt(encryptor.encrypt(block))
+
+    file_mac = str_to_a32(mac_str)
+    temp_output_file.close()
+
+    if (file_mac[0] ^ file_mac[1], file_mac[2] ^ file_mac[3]) != file_key[6:8]: raise ValueError
+
+    file_path = os.path.join(dest_path, attribs['n'])
+    if os.path.exists(file_path): os.remove(file_path)
+
+    shutil.move(temp_output_file.name, file_path)
+
+def mega_download_url(url, dest_path=None):
+    if '/file/' in url:
+        url = url.replace(' ', '')
+        file_id = re.findall(r'\W\w\w\w\w\w\w\w\w\W', url)[0][1:-1]
+        path = f'{file_id}!{url[re.search(file_id, url).end() + 1:]}'.split('!')
+    elif '!' in url: path = re.findall(r'/#!(.*)', url)[0].split('!')
+    else: raise Exception
+
+    return mega_download_file(path[0], path[1], dest_path)