sao: add decoder helpers, hash checks

example_config/sao.yaml

@@ -7,3 +7,7 @@ crypt:
   enable: False
   key: ""
   iv: ""
+
+hash:
+  verify_hash: False
+  hash_base: ""

titles/sao/config.py

@@ -51,8 +51,25 @@ class SaoCryptConfig:
             self.__config, "sao", "crypt", "iv", default=""
         )
 
+class SaoHashConfig:
+    def __init__(self, parent_config: "SaoConfig"):
+        self.__config = parent_config
+        
+    @property
+    def verify_hash(self) -> bool:
+        return CoreConfig.get_config_field(
+            self.__config, "sao", "hash", "verify_hash", default=False
+        )
+    
+    @property
+    def hash_base(self) -> str:
+        return CoreConfig.get_config_field(
+            self.__config, "sao", "hash", "hash_base", default=""
+        )
+
 
 class SaoConfig(dict):
     def __init__(self) -> None:
         self.server = SaoServerConfig(self)
         self.crypt = SaoCryptConfig(self)
+        self.hash = SaoHashConfig(self)

titles/sao/handlers/__init__.py

@@ -1 +1,2 @@
-from titles.sao.handlers.base import *
+from .base import *
+from .helpers import *

titles/sao/handlers/base.py

@@ -1,22 +1,26 @@
 import struct
 from datetime import datetime
 from construct import *
-import sys
+from .helpers import *
 import csv
 from csv import *
 
 class SaoRequestHeader:
     def __init__(self, data: bytes) -> None:
-        collection = struct.unpack_from("!H6xIII16s", data)
+        collection = struct.unpack_from("!H6xIII16sI", data)
         self.cmd: int = collection[0]
         self.vendor_id: int = collection[1]
         self.game_id: int = collection[2]
         self.version_id: int = collection[3]
-        self.checksum: str = collection[4]
+        self.hash: str = collection[4]
+        self.data_len: str = collection[5]
 
 class SaoBaseRequest:
     def __init__(self, header: SaoRequestHeader, data: bytes) -> None:
         self.header = header
+        if self.header.data_len != len(data):
+            logging.getLogger('sao').error(f"Expected {self.header.data_len} data bytes byt got {len(data)}!")
+            # TODO: Raise an error here
 
 class SaoBaseResponse:
     def __init__(self, cmd_id: int) -> None:
@@ -2750,3 +2754,25 @@ class SaoScanQrQuestProfileCardResponse(SaoBaseResponse):
 
         self.length = len(resp_data)
         return super().make() + resp_data
+    
+class SaoConsumeCreditGuestRequest(SaoBaseRequest):
+    def __init__(self, header: SaoRequestHeader, data: bytes) -> None:
+        super().__init__(header, data)
+        off = 0
+        shop_id = decode_str(data, off)
+        self.shop_id = shop_id[0]
+        off += shop_id[1]
+        
+        serial_num = decode_str(data, off)
+        self.serial_num = serial_num[0]
+        off += serial_num[1]
+        
+        self.cab_type = decode_byte(data, off)
+        off += BYTE_OFF
+        
+        self.act_type = decode_byte(data, off)
+        off += BYTE_OFF
+        
+        self.consume_num = decode_byte(data, off)
+        off += BYTE_OFF
+        

titles/sao/handlers/helpers.py

@@ -0,0 +1,50 @@
+from typing import Tuple
+import struct
+import logging
+
+BIGINT_OFF = 16
+LONG_OFF = 8
+INT_OFF = 4
+SHORT_OFF = 2
+BYTE_OFF = 1
+
+def decode_num(data: bytes, offset: int, size: int) -> int:
+    try:
+        return int.from_bytes(data[offset:offset + size], 'big')
+    except:
+        logging.getLogger('sao').error(f"Failed to parse {data[offset:offset + size]} as BE number of width {size}")
+        return 0
+
+def decode_byte(data: bytes, offset: int) -> int:
+    return decode_num(data, offset, BYTE_OFF)
+
+def decode_short(data: bytes, offset: int) -> int:
+    return decode_num(data, offset, SHORT_OFF)
+
+def decode_int(data: bytes, offset: int) -> int:
+    return decode_num(data, offset, INT_OFF)
+
+def decode_long(data: bytes, offset: int) -> int:
+    return decode_num(data, offset, LONG_OFF)
+
+def decode_bigint(data: bytes, offset: int) -> int:
+    return decode_num(data, offset, BIGINT_OFF)
+
+def decode_str(data: bytes, offset: int) -> Tuple[str, int]:
+    try:
+        str_len = decode_int(data, offset)
+        num_bytes_decoded = INT_OFF + str_len
+        str_out = data[offset + INT_OFF:offset + num_bytes_decoded].decode("utf-16-le", errors="replace")
+        return (str_out, num_bytes_decoded)
+    except:
+        logging.getLogger('sao').error(f"Failed to parse {data[offset:]} as string!")
+        return ("", 0)
+
+def encode_str(s: str) -> bytes:
+    try:
+        str_bytes = s.encode("utf-16-le", errors="replace")
+        str_len_bytes = struct.pack("!I", len(str_bytes))
+        return str_len_bytes + str_bytes
+    except:
+        logging.getLogger('sao').error(f"Failed to encode {s} as bytes!")
+        return b""

titles/sao/index.py

@@ -5,6 +5,7 @@ import logging, coloredlogs
 from logging.handlers import TimedRotatingFileHandler
 from os import path
 from Crypto.Cipher import Blowfish
+from hashlib import md5
 
 from core import CoreConfig, Utils
 from core.title import BaseServlet
@@ -48,6 +49,10 @@ class SaoServlet(BaseServlet):
             self.logger.inited = True
 
         self.base = SaoBase(core_cfg, self.game_cfg)
+        self.static_hash = None
+        
+        if self.game_cfg.hash.verify_hash:
+            self.static_hash = md5(self.game_cfg.hash.hash_base) # Greate hashing guys, really validates the data
     
     def get_endpoint_matchers(self) -> Tuple[List[Tuple[str, str, Dict]], List[Tuple[str, str, Dict]]]:
         return (
@@ -93,14 +98,20 @@ class SaoServlet(BaseServlet):
         
         cmd_str = f"{req_header.cmd:04x}"
         
+        if self.game_cfg.hash.verify_hash and self.static_hash != req_header.hash:
+            self.logger.error(f"Hash mismatch! Expecting {self.static_hash} but recieved {req_header.hash}")
+            return b""
+        
         if self.game_cfg.crypt.enable:
-            iv = req_raw[30:38]
+            
+            iv = req_raw[40:48]
             cipher = Blowfish.new(self.game_cfg.crypt.key, Blowfish.MODE_CBC, iv)
-            crypt_data = req_raw[38:]
+            crypt_data = req_raw[48:]
             req_data = cipher.decrypt(crypt_data)
+            self.logger.debug(f"Decrypted {req_data.hex()} with IV {iv.hex()}")
             
         else:
-            req_data = req_raw[30:]
+            req_data = req_raw[40:]
 
         handler = getattr(self.base, f"handle_{cmd_str}", None)
         if handler is None: