Merge pull request #709 from ostjen/fix-ir-large-payload

Raise parse_header payload ceiling so large IR learn frames decode

Author: jasonacox

RELEASE.md

@@ -1,5 +1,9 @@
 # RELEASE NOTES
 
+## v1.18.1 - IR Learn Frame Fix
+
+* core: Added `MAX_PAYLOAD_LENGTH` constant (default 1440 bytes) in `tinytuya/core/const.py` to replace the hardcoded 1000-byte ceiling in `parse_header()`. Enables local IR learn frame capture from devices with larger payloads such as AC IR blasters. Fixes [#708](https://github.com/jasonacox/tinytuya/issues/708) via [#709](https://github.com/jasonacox/tinytuya/pull/709) by @ostjen.
+
 ## v1.18.0 - Format Handling and UX Improvements
 
 * `devices.json` format: All loading paths (library, CLI, scanner, wizard, API server) now support both a flat `[{...}]` list and the `{"devices": [{...}]}` wrapped-dict format via a new centralized `load_devicefile()` helper. Fixes [#532](https://github.com/jasonacox/tinytuya/issues/532) via [#700](https://github.com/jasonacox/tinytuya/pull/700) by @uzlonewolf and @jasonacox.

tests.py

@@ -20,6 +20,8 @@
 
 import tinytuya
 from tinytuya.Contrib.RFRemoteControlDevice import RFRemoteControlDevice
+from tinytuya.core import message_helper as mh
+from tinytuya.core.exceptions import DecodeError
 
 LOCAL_KEY = '0123456789abcdef'
 
@@ -384,5 +386,26 @@ def test_special_chars_in_key(self):
         self.assertEqual(result[0]['key'], ":|S'vf<MT6xhr{1~")
 
 
+class TestParseHeader(unittest.TestCase):
+    """parse_header must accept large IR/AC learn frames (>1000 bytes) while
+    still rejecting absurd sizes from a corrupt or desynced stream."""
+
+    def _header_6699(self, payload_len):
+        return struct.pack(
+            mh.H.MESSAGE_HEADER_FMT_6699,
+            mh.H.PREFIX_6699_VALUE, 0, 1, 8, payload_len,
+        )
+
+    def test_large_ir_payload_accepted(self):
+        # a 1038-byte frame is a real air-conditioner learn report; it must parse
+        header = mh.parse_header(self._header_6699(1038) + b'\x00' * 40)
+        self.assertEqual(header.length, 1038)
+
+    def test_oversized_payload_rejected(self):
+        oversized = self._header_6699(mh.MAX_PAYLOAD_LENGTH + 1)
+        with self.assertRaises(DecodeError):
+            mh.parse_header(oversized + b'\x00' * 40)
+
+
 if __name__ == '__main__':
     unittest.main()

tinytuya/core/const.py

@@ -12,6 +12,12 @@
 TCPTIMEOUT = 0.4    # Seconds to wait for socket open for scanning
 DEFAULT_NETWORK = '192.168.0.0/24'
 
+# Heuristic ceiling used to reject corrupt/desynced streams. Most devices only
+# have ~256 KiB of RAM and need 2x-3x the payload size for buffers, plus packets
+# over ~1440 bytes tend to fragment, so keep the default conservative. Override
+# at runtime if a particular device needs larger frames.
+MAX_PAYLOAD_LENGTH = 1440
+
 # Configuration Files
 CONFIGFILE = 'tinytuya.json'
 DEVICEFILE = 'devices.json'

tinytuya/core/core.py

@@ -101,7 +101,7 @@
 if HAVE_COLORAMA:
     init()
 
-version_tuple = (1, 18, 0)  # Major, Minor, Patch
+version_tuple = (1, 18, 1)  # Major, Minor, Patch
 version = __version__ = "%d.%d.%d" % version_tuple
 __author__ = "jasonacox"
 

tinytuya/core/message_helper.py

@@ -10,6 +10,7 @@
 
 from .crypto_helper import AESCipher
 from .exceptions import DecodeError
+from .const import MAX_PAYLOAD_LENGTH
 from . import header as H
 
 log = logging.getLogger(__name__)
@@ -91,9 +92,9 @@ def parse_header(data):
         #log.debug('Header prefix wrong! %08X != %08X', prefix, PREFIX_VALUE)
         raise DecodeError('Header prefix wrong! %08X is not %08X or %08X' % (prefix, H.PREFIX_55AA_VALUE, H.PREFIX_6699_VALUE))
 
-    # sanity check. currently the max payload length is somewhere around 300 bytes
-    if payload_len > 1000:
-        raise DecodeError('Header claims the packet size is over 1000 bytes!  It is most likely corrupt.  Claimed size: %d bytes. fmt:%s unpacked:%r' % (payload_len,fmt,unpacked))
+    # sanity check to catch a corrupt/desynced stream (see MAX_PAYLOAD_LENGTH)
+    if payload_len > MAX_PAYLOAD_LENGTH:
+        raise DecodeError('Header claims the packet size is over %d bytes!  It is most likely corrupt.  Claimed size: %d bytes. fmt:%s unpacked:%r' % (MAX_PAYLOAD_LENGTH,payload_len,fmt,unpacked))
 
     return TuyaHeader(prefix, seqno, cmd, payload_len, total_length)