converted processIncomingPacket.

pymodbus/framer/rtu_framer.py

@@ -64,6 +64,7 @@ def __init__(self, decoder, client=None):
         self._hsize = 0x01
         self._end = b"\x0d\x0a"
         self._min_frame_size = 4
+        self.function_codes = set(self.decoder.lookup) if self.decoder else {}
 
     # ----------------------------------------------------------------------- #
     # Private Helper Functions
@@ -191,6 +192,23 @@ def populateResult(self, result):
         result.slave_id = self._header["uid"]
         result.transaction_id = self._header["uid"]
 
+    def getFrameStart(self, slaves, broadcast, skip_cur_frame):
+        """Scan buffer for a relevant frame start."""
+        start = 1 if skip_cur_frame else 0
+        if (buf_len := len(self._buffer)) < 4:
+            return False
+        for i in range(start, buf_len - 3):  # <slave id><function code><crc 2 bytes>
+            if not broadcast and self._buffer[i] not in slaves:
+                continue
+            if self._buffer[i + 1] not in self.function_codes:
+                continue
+            if i:
+                self._buffer = self._buffer[i:]  # remove preceding trash.
+            return True
+        if buf_len > 3:
+            self._buffer = self._buffer[-3:]
+        return False
+
     # ----------------------------------------------------------------------- #
     # Public Member Functions
     # ----------------------------------------------------------------------- #
@@ -214,25 +232,25 @@ def processIncomingPacket(self, data, callback, slave, **kwargs):
         """
         if not isinstance(slave, (list, tuple)):
             slave = [slave]
+        broadcast = not slave[0]
         self.addToFrame(data)
         single = kwargs.get("single", False)
-        while True:
-            if self.isFrameReady():
-                if self.checkFrame():
-                    if self._validate_slave_id(slave, single):
-                        self._process(callback)
-                    else:
-                        header_txt = self._header["uid"]
-                        Log.debug("Not a valid slave id - {}, ignoring!!", header_txt)
-                        self.resetFrame()
-                        break
-                else:
-                    Log.debug("Frame check failed, ignoring!!")
-                    self.resetFrame()
-                    break
-            else:
+        skip_cur_frame = False
+        while self.getFrameStart(slave, broadcast, skip_cur_frame):
+            skip_cur_frame = True
+            if not self.isFrameReady():
                 Log.debug("Frame - [{}] not ready", data)
                 break
+            if not self.checkFrame():
+                Log.debug("Frame check failed, ignoring!!")
+                self.resetFrame()
+                break
+            if not self._validate_slave_id(slave, single):
+                header_txt = self._header["uid"]
+                Log.debug("Not a valid slave id - {}, ignoring!!", header_txt)
+                self.resetFrame()
+                break
+            self._process(callback)
 
     def buildPacket(self, message):
         """Create a ready to send modbus packet.

test/test_client_multidrop.py

@@ -63,15 +63,13 @@ def test_big_split_response_frame_from_other_unit(self, framer, callback):
             framer.processIncomingPacket(serial_event, callback, self.slaves)
         callback.assert_not_called()
 
-    @pytest.mark.skip
     def test_split_frame(self, framer, callback):
         """Test split frame."""
         serial_events = [self.good_frame[:5], self.good_frame[5:]]
         for serial_event in serial_events:
             framer.processIncomingPacket(serial_event, callback, self.slaves)
         callback.assert_called_once()
 
-    @pytest.mark.skip
     def test_complete_frame_trailing_data_without_unit_id(self, framer, callback):
         """Test trailing data."""
         garbage = b"\x05\x04\x03"  # Note the garbage doesn't contain our unit id
@@ -138,13 +136,29 @@ def test_frame_with_trailing_data(self, framer, callback):
         # We should not respond in this case for identical reasons as test_wrapped_frame
         callback.assert_not_called()
 
-    @pytest.mark.skip
-    def test_getFrameStart(self, framer, callback):
+    def test_getFrameStart(self, framer):
         """Test getFrameStart."""
         framer_ok = b"\x02\x03\x00\x01\x00}\xd4\x18"
-        framer._buffer = framer_ok + framer_ok
-        assert framer.getFrameStart(self.slaves, False)
-        assert framer_ok + framer_ok == framer._buffer
-        assert framer.getFrameStart(self.slaves, True)
-        assert framer_ok == framer._buffer
-        assert not framer.getFrameStart(self.slaves, True)
+        framer._buffer = framer_ok  # pylint: disable=protected-access
+        assert framer.getFrameStart(self.slaves, False, False)
+        assert framer_ok == framer._buffer  # pylint: disable=protected-access
+
+        framer_2ok = framer_ok + framer_ok
+        framer._buffer = framer_2ok  # pylint: disable=protected-access
+        assert framer.getFrameStart(self.slaves, False, False)
+        assert framer_2ok == framer._buffer  # pylint: disable=protected-access
+        assert framer.getFrameStart(self.slaves, False, True)
+        assert framer_ok == framer._buffer  # pylint: disable=protected-access
+
+        framer._buffer = framer_ok[:2]  # pylint: disable=protected-access
+        assert not framer.getFrameStart(self.slaves, False, False)
+        assert framer_ok[:2] == framer._buffer  # pylint: disable=protected-access
+
+        framer._buffer = framer_ok[:3]  # pylint: disable=protected-access
+        assert not framer.getFrameStart(self.slaves, False, False)
+        assert framer_ok[:3] == framer._buffer  # pylint: disable=protected-access
+
+        framer_ok = b"\xF0\x03\x00\x01\x00}\xd4\x18"
+        framer._buffer = framer_ok  # pylint: disable=protected-access
+        assert not framer.getFrameStart(self.slaves, False, False)
+        assert framer._buffer == framer_ok[-3:]  # pylint: disable=protected-access

test/test_framers.py

@@ -255,10 +255,10 @@ def test_populate_result(rtu_framer):  # pylint: disable=redefined-outer-name
         (
             b"\x11\x03\x06\xAE\x41\x56\x52\x43\x40\x49\xAD",
             16,
-            True,
+            False,
             False,
         ),  # incorrect slave id
-        (b"\x11\x03\x06\xAE\x41\x56\x52\x43\x40\x49\xAD\x11\x03", 17, True, False),
+        (b"\x11\x03\x06\xAE\x41\x56\x52\x43\x40\x49\xAD\x11\x03", 17, False, True),
         # good frame + part of next frame
     ],
 )