Adding inform reader

2 files changed, 132 insertions, 0 deletions

diff --git a/inform.py b/inform.py
new file mode 100644
index 0000000..8c4b3e0
--- /dev/null
+++ b/inform.py
@@ -0,0 +1,102 @@
+import struct
+import binascii
+from Crypto.Cipher import AES
+
+
+class BinaryDataStream(object):
+
+    def __init__(self, data):
+        self.data = data
+
+    def read_int(self):
+        return struct.unpack(">i", self.data.read(4))[0]
+
+    def read_short(self):
+        return struct.unpack(">h", self.data.read(2))[0]
+
+    def read_string(self, length):
+        return self.data.read(length)
+
+
+class Cryptor(object):
+
+    def __init__(self, key, iv):
+        self.iv = iv
+        self.key = key
+        self.cipher = AES.new(key.decode("hex"), AES.MODE_CBC, iv)
+
+    @staticmethod
+    def unpad(s):
+        return s[0:-ord(s[-1])]
+
+    @staticmethod
+    def pad(s, BS=16):
+        return s + (BS - len(s) % BS) * chr(BS - len(s) % BS) 
+
+    def decrypt(self, payload):
+        return self.unpad(self.cipher.decrypt(payload))
+
+
+class InformParser(object):
+
+    PROTOCOL_MAGIC = 1414414933
+    MAX_VERSION = 1
+
+    ENCRYPTED_FLAG = 0x1
+    COMPRESSED_FLAG = 0x2
+
+    def __init__(self, input_stream, key):
+        self.input_stream = input_stream
+        self.key = key
+
+        self.magic_number = None
+        self.version = None
+        self.mac_addr = None
+        self.flags = None
+        self.iv = None
+        self.data_version = None
+        self.data_length = None
+        self.payload = None
+
+    @classmethod
+    def open(cls, filename, key):
+        return cls(BinaryDataStream(open(filename, "rb")), key)
+
+    @staticmethod
+    def _format_mac_addr(mac_bytes):
+        return "-".join([binascii.hexlify(i) for i in mac_bytes])
+
+    def _has_flag(self, flag):
+        return self.flags & flag != 0
+
+    @property
+    def formatted_mac_addr(self):
+        return self._format_mac_addr(self.mac_addr)
+
+    @property
+    def is_encrypted(self):
+        return self._has_flag(self.ENCRYPTED_FLAG)
+
+    @property
+    def is_compressed(self):
+        return self._has_flag(self.COMPRESSED_FLAG)
+
+    @property
+    def decrypted_payload(self):
+        return Cryptor(self.key, self.iv).decrypt(self.payload)
+
+    def parse(self):
+        self.magic = self.input_stream.read_int()
+        assert self.magic == self.PROTOCOL_MAGIC
+
+        self.version = self.input_stream.read_int()
+        assert self.version < self.MAX_VERSION
+
+        self.mac_addr = self.input_stream.read_string(6)
+        self.flags = self.input_stream.read_short()
+        self.iv = self.input_stream.read_string(16)
+        self.data_version = self.input_stream.read_int()
+        self.data_length = self.input_stream.read_int()
+        self.payload = self.input_stream.read_string(self.data_length)
+
+        return self
diff --git a/inform_protocol.txt b/inform_protocol.txt
new file mode 100644
index 0000000..f4d9c41
--- /dev/null
+++ b/inform_protocol.txt
@@ -0,0 +1,30 @@
+Ubiquiti Inform Protocol
+========================
+
+These are just some unstructured notes about the inform protocol at this point.
+
+Packet Structure
+----------------
+4 bytes          magic number            integer
+4 bytes          version                 integer
+6 bytes          hwaddr                  string
+2 bytes          flags                   short
+16 bytes         initialization vector   string
+4 bytes          data version            integer
+4 bytes          data length             integer
+n bytes          encrypted payload       string
+
+
+magic must == 1414414933
+data version must < 1
+flags & 0x1 != 0 means encrypted
+flags & 0x2 != 0 means compressed
+
+
+The payload is AES encrypted in CBC mode using PKCS5 padding. They key is the
+device auth key from the database or a master key that is hard coded if the
+device hasn't been provisioned yet. The master key is hard coded in the
+controller code in the DeviceManager class and pretty easy to find.
+
+
+MASTER_KEY = "ba86f2bbe107c7c57eb5f2690775c712"