RFCOMM: Slightly refactor and correct constants

bumble/rfcomm.py

@@ -19,6 +19,7 @@
 
 import logging
 import asyncio
+import dataclasses
 import enum
 from typing import Callable, Dict, List, Optional, Tuple, Union, TYPE_CHECKING
 
@@ -60,27 +61,18 @@
 
 RFCOMM_PSM = 0x0003
 
+class FrameType(enum.IntEnum):
+    SABM = 0x2F  # Control field [1,1,1,1,_,1,0,0] LSB-first
+    UA   = 0x63  # Control field [0,1,1,0,_,0,1,1] LSB-first
+    DM   = 0x0F  # Control field [1,1,1,1,_,0,0,0] LSB-first
+    DISC = 0x43  # Control field [0,1,0,_,0,0,1,1] LSB-first
+    UIH  = 0xEF  # Control field [1,1,1,_,1,1,1,1] LSB-first
+    UI   = 0x03  # Control field [0,0,0,_,0,0,1,1] LSB-first
 
-# Frame types
-RFCOMM_SABM_FRAME = 0x2F  # Control field [1,1,1,1,_,1,0,0] LSB-first
-RFCOMM_UA_FRAME   = 0x63  # Control field [0,1,1,0,_,0,1,1] LSB-first
-RFCOMM_DM_FRAME   = 0x0F  # Control field [1,1,1,1,_,0,0,0] LSB-first
-RFCOMM_DISC_FRAME = 0x43  # Control field [0,1,0,_,0,0,1,1] LSB-first
-RFCOMM_UIH_FRAME  = 0xEF  # Control field [1,1,1,_,1,1,1,1] LSB-first
-RFCOMM_UI_FRAME   = 0x03  # Control field [0,0,0,_,0,0,1,1] LSB-first
+class MccType(enum.IntEnum):
+    PN  = 0x20
+    MSC = 0x38
 
-RFCOMM_FRAME_TYPE_NAMES = {
-    RFCOMM_SABM_FRAME: 'SABM',
-    RFCOMM_UA_FRAME:   'UA',
-    RFCOMM_DM_FRAME:   'DM',
-    RFCOMM_DISC_FRAME: 'DISC',
-    RFCOMM_UIH_FRAME:  'UIH',
-    RFCOMM_UI_FRAME:   'UI'
-}
-
-# MCC Types
-RFCOMM_MCC_PN_TYPE  = 0x20
-RFCOMM_MCC_MSC_TYPE = 0x38
 
 # FCS CRC
 CRC_TABLE = bytes([
@@ -118,7 +110,7 @@
     0XBA, 0X2B, 0X59, 0XC8, 0XBD, 0X2C, 0X5E, 0XCF
 ])
 
-RFCOMM_DEFAULT_WINDOW_SIZE    = 16
+RFCOMM_DEFAULT_WINDOW_SIZE    = 7
 RFCOMM_DEFAULT_MAX_FRAME_SIZE = 2000
 
 RFCOMM_DYNAMIC_CHANNEL_NUMBER_START = 1
@@ -183,7 +175,7 @@ def compute_fcs(buffer: bytes) -> int:
 class RFCOMM_Frame:
     def __init__(
         self,
-        frame_type: int,
+        frame_type: FrameType,
         c_r: int,
         dlci: int,
         p_f: int,
@@ -206,14 +198,11 @@ def __init__(
             self.length = bytes([(length << 1) | 1])
         self.address = (dlci << 2) | (c_r << 1) | 1
         self.control = frame_type | (p_f << 4)
-        if frame_type == RFCOMM_UIH_FRAME:
+        if frame_type == FrameType.UIH:
             self.fcs = compute_fcs(bytes([self.address, self.control]))
         else:
             self.fcs = compute_fcs(bytes([self.address, self.control]) + self.length)
 
-    def type_name(self) -> str:
-        return RFCOMM_FRAME_TYPE_NAMES[self.type]
-
     @staticmethod
     def parse_mcc(data) -> Tuple[int, bool, bytes]:
         mcc_type = data[0] >> 2
@@ -237,32 +226,32 @@ def make_mcc(mcc_type: int, c_r: int, data: bytes) -> bytes:
 
     @staticmethod
     def sabm(c_r: int, dlci: int):
-        return RFCOMM_Frame(RFCOMM_SABM_FRAME, c_r, dlci, 1)
+        return RFCOMM_Frame(FrameType.SABM, c_r, dlci, 1)
 
     @staticmethod
     def ua(c_r: int, dlci: int):
-        return RFCOMM_Frame(RFCOMM_UA_FRAME, c_r, dlci, 1)
+        return RFCOMM_Frame(FrameType.UA, c_r, dlci, 1)
 
     @staticmethod
     def dm(c_r: int, dlci: int):
-        return RFCOMM_Frame(RFCOMM_DM_FRAME, c_r, dlci, 1)
+        return RFCOMM_Frame(FrameType.DM, c_r, dlci, 1)
 
     @staticmethod
     def disc(c_r: int, dlci: int):
-        return RFCOMM_Frame(RFCOMM_DISC_FRAME, c_r, dlci, 1)
+        return RFCOMM_Frame(FrameType.DISC, c_r, dlci, 1)
 
     @staticmethod
     def uih(c_r: int, dlci: int, information: bytes, p_f: int = 0):
         return RFCOMM_Frame(
-            RFCOMM_UIH_FRAME, c_r, dlci, p_f, information, with_credits=(p_f == 1)
+            FrameType.UIH, c_r, dlci, p_f, information, with_credits=(p_f == 1)
         )
 
     @staticmethod
     def from_bytes(data: bytes) -> RFCOMM_Frame:
         # Extract fields
         dlci = (data[0] >> 2) & 0x3F
         c_r = (data[0] >> 1) & 0x01
-        frame_type = data[1] & 0xEF
+        frame_type = FrameType(data[1] & 0xEF)
         p_f = (data[1] >> 4) & 0x01
         length = data[2]
         if length & 0x01:
@@ -291,7 +280,7 @@ def __bytes__(self) -> bytes:
 
     def __str__(self) -> str:
         return (
-            f'{color(self.type_name(), "yellow")}'
+            f'{color(self.type.name, "yellow")}'
             f'(c/r={self.c_r},'
             f'dlci={self.dlci},'
             f'p/f={self.p_f},'
@@ -301,6 +290,7 @@ def __str__(self) -> str:
 
 
 # -----------------------------------------------------------------------------
+@dataclasses.dataclass
 class RFCOMM_MCC_PN:
     dlci: int
     cl: int
@@ -310,23 +300,11 @@ class RFCOMM_MCC_PN:
     max_retransmissions: int
     window_size: int
 
-    def __init__(
-        self,
-        dlci: int,
-        cl: int,
-        priority: int,
-        ack_timer: int,
-        max_frame_size: int,
-        max_retransmissions: int,
-        window_size: int,
-    ) -> None:
-        self.dlci = dlci
-        self.cl = cl
-        self.priority = priority
-        self.ack_timer = ack_timer
-        self.max_frame_size = max_frame_size
-        self.max_retransmissions = max_retransmissions
-        self.window_size = window_size
+    def __post_init__(self) -> None:
+        if self.window_size < 1 or self.window_size > 7:
+            logger.warning(
+                f'Error Recovery Window size {self.window_size} is out of range [1, 7].'
+            )
 
     @staticmethod
     def from_bytes(data: bytes) -> RFCOMM_MCC_PN:
@@ -337,7 +315,7 @@ def from_bytes(data: bytes) -> RFCOMM_MCC_PN:
             ack_timer=data[3],
             max_frame_size=data[4] | data[5] << 8,
             max_retransmissions=data[6],
-            window_size=data[7],
+            window_size=data[7] & 0x07,
         )
 
     def __bytes__(self) -> bytes:
@@ -350,23 +328,14 @@ def __bytes__(self) -> bytes:
                 self.max_frame_size & 0xFF,
                 (self.max_frame_size >> 8) & 0xFF,
                 self.max_retransmissions & 0xFF,
-                self.window_size & 0xFF,
+                # Only 3 bits are meaningful.
+                self.window_size & 0x07,
             ]
         )
 
-    def __str__(self) -> str:
-        return (
-            f'PN(dlci={self.dlci},'
-            f'cl={self.cl},'
-            f'priority={self.priority},'
-            f'ack_timer={self.ack_timer},'
-            f'max_frame_size={self.max_frame_size},'
-            f'max_retransmissions={self.max_retransmissions},'
-            f'window_size={self.window_size})'
-        )
-
 
 # -----------------------------------------------------------------------------
+@dataclasses.dataclass
 class RFCOMM_MCC_MSC:
     dlci: int
     fc: int
@@ -375,16 +344,6 @@ class RFCOMM_MCC_MSC:
     ic: int
     dv: int
 
-    def __init__(
-        self, dlci: int, fc: int, rtc: int, rtr: int, ic: int, dv: int
-    ) -> None:
-        self.dlci = dlci
-        self.fc = fc
-        self.rtc = rtc
-        self.rtr = rtr
-        self.ic = ic
-        self.dv = dv
-
     @staticmethod
     def from_bytes(data: bytes) -> RFCOMM_MCC_MSC:
         return RFCOMM_MCC_MSC(
@@ -409,16 +368,6 @@ def __bytes__(self) -> bytes:
             ]
         )
 
-    def __str__(self) -> str:
-        return (
-            f'MSC(dlci={self.dlci},'
-            f'fc={self.fc},'
-            f'rtc={self.rtc},'
-            f'rtr={self.rtr},'
-            f'ic={self.ic},'
-            f'dv={self.dv})'
-        )
-
 
 # -----------------------------------------------------------------------------
 class DLC(EventEmitter):
@@ -471,7 +420,7 @@ def send_frame(self, frame: RFCOMM_Frame) -> None:
         self.multiplexer.send_frame(frame)
 
     def on_frame(self, frame: RFCOMM_Frame) -> None:
-        handler = getattr(self, f'on_{frame.type_name()}_frame'.lower())
+        handler = getattr(self, f'on_{frame.type.name}_frame'.lower())
         handler(frame)
 
     def on_sabm_frame(self, _frame: RFCOMM_Frame) -> None:
@@ -485,9 +434,7 @@ def on_sabm_frame(self, _frame: RFCOMM_Frame) -> None:
 
         # Exchange the modem status with the peer
         msc = RFCOMM_MCC_MSC(dlci=self.dlci, fc=0, rtc=1, rtr=1, ic=0, dv=1)
-        mcc = RFCOMM_Frame.make_mcc(
-            mcc_type=RFCOMM_MCC_MSC_TYPE, c_r=1, data=bytes(msc)
-        )
+        mcc = RFCOMM_Frame.make_mcc(mcc_type=MccType.MSC, c_r=1, data=bytes(msc))
         logger.debug(f'>>> MCC MSC Command: {msc}')
         self.send_frame(RFCOMM_Frame.uih(c_r=self.c_r, dlci=0, information=mcc))
 
@@ -503,9 +450,7 @@ def on_ua_frame(self, _frame: RFCOMM_Frame) -> None:
 
         # Exchange the modem status with the peer
         msc = RFCOMM_MCC_MSC(dlci=self.dlci, fc=0, rtc=1, rtr=1, ic=0, dv=1)
-        mcc = RFCOMM_Frame.make_mcc(
-            mcc_type=RFCOMM_MCC_MSC_TYPE, c_r=1, data=bytes(msc)
-        )
+        mcc = RFCOMM_Frame.make_mcc(mcc_type=MccType.MSC, c_r=1, data=bytes(msc))
         logger.debug(f'>>> MCC MSC Command: {msc}')
         self.send_frame(RFCOMM_Frame.uih(c_r=self.c_r, dlci=0, information=mcc))
 
@@ -559,9 +504,7 @@ def on_mcc_msc(self, c_r: bool, msc: RFCOMM_MCC_MSC) -> None:
             # Command
             logger.debug(f'<<< MCC MSC Command: {msc}')
             msc = RFCOMM_MCC_MSC(dlci=self.dlci, fc=0, rtc=1, rtr=1, ic=0, dv=1)
-            mcc = RFCOMM_Frame.make_mcc(
-                mcc_type=RFCOMM_MCC_MSC_TYPE, c_r=0, data=bytes(msc)
-            )
+            mcc = RFCOMM_Frame.make_mcc(mcc_type=MccType.MSC, c_r=0, data=bytes(msc))
             logger.debug(f'>>> MCC MSC Response: {msc}')
             self.send_frame(RFCOMM_Frame.uih(c_r=self.c_r, dlci=0, information=mcc))
         else:
@@ -589,7 +532,7 @@ def accept(self) -> None:
             max_retransmissions=0,
             window_size=self.window_size,
         )
-        mcc = RFCOMM_Frame.make_mcc(mcc_type=RFCOMM_MCC_PN_TYPE, c_r=0, data=bytes(pn))
+        mcc = RFCOMM_Frame.make_mcc(mcc_type=MccType.PN, c_r=0, data=bytes(pn))
         logger.debug(f'>>> PN Response: {pn}')
         self.send_frame(RFCOMM_Frame.uih(c_r=self.c_r, dlci=0, information=mcc))
         self.change_state(DLC.State.CONNECTING)
@@ -711,7 +654,7 @@ def on_pdu(self, pdu: bytes) -> None:
         if frame.dlci == 0:
             self.on_frame(frame)
         else:
-            if frame.type == RFCOMM_DM_FRAME:
+            if frame.type == FrameType.DM:
                 # DM responses are for a DLCI, but since we only create the dlc when we
                 # receive a PN response (because we need the parameters), we handle DM
                 # frames at the Multiplexer level
@@ -724,7 +667,7 @@ def on_pdu(self, pdu: bytes) -> None:
                 dlc.on_frame(frame)
 
     def on_frame(self, frame: RFCOMM_Frame) -> None:
-        handler = getattr(self, f'on_{frame.type_name()}_frame'.lower())
+        handler = getattr(self, f'on_{frame.type.name}_frame'.lower())
         handler(frame)
 
     def on_sabm_frame(self, _frame: RFCOMM_Frame) -> None:
@@ -772,10 +715,10 @@ def on_disc_frame(self, _frame: RFCOMM_Frame) -> None:
     def on_uih_frame(self, frame: RFCOMM_Frame) -> None:
         (mcc_type, c_r, value) = RFCOMM_Frame.parse_mcc(frame.information)
 
-        if mcc_type == RFCOMM_MCC_PN_TYPE:
+        if mcc_type == MccType.PN:
             pn = RFCOMM_MCC_PN.from_bytes(value)
             self.on_mcc_pn(c_r, pn)
-        elif mcc_type == RFCOMM_MCC_MSC_TYPE:
+        elif mcc_type == MccType.MSC:
             mcs = RFCOMM_MCC_MSC.from_bytes(value)
             self.on_mcc_msc(c_r, mcs)
 
@@ -871,7 +814,7 @@ async def open_dlc(
             max_retransmissions=0,
             window_size=window_size,
         )
-        mcc = RFCOMM_Frame.make_mcc(mcc_type=RFCOMM_MCC_PN_TYPE, c_r=1, data=bytes(pn))
+        mcc = RFCOMM_Frame.make_mcc(mcc_type=MccType.PN, c_r=1, data=bytes(pn))
         logger.debug(f'>>> Sending MCC: {pn}')
         self.open_result = asyncio.get_running_loop().create_future()
         self.change_state(Multiplexer.State.OPENING)

tests/rfcomm_test.py

@@ -15,7 +15,11 @@
 # -----------------------------------------------------------------------------
 # Imports
 # -----------------------------------------------------------------------------
-from bumble.rfcomm import RFCOMM_Frame
+import asyncio
+import pytest
+
+from . import test_utils
+from bumble.rfcomm import RFCOMM_Frame, Server, Client, DLC
 
 
 # -----------------------------------------------------------------------------
@@ -43,6 +47,29 @@ def test_frames():
     basic_frame_check(frame)
 
 
+# -----------------------------------------------------------------------------
+@pytest.mark.asyncio
+async def test_basic_connection():
+    devices = test_utils.TwoDevices()
+    await devices.setup_connection()
+
+    accept_future: asyncio.Future[DLC] = asyncio.get_running_loop().create_future()
+    channel = Server(devices[0]).listen(acceptor=accept_future.set_result)
+
+    multiplexer = await Client(devices.connections[1]).start()
+    dlcs = await asyncio.gather(accept_future, multiplexer.open_dlc(channel))
+
+    queues = [asyncio.Queue(), asyncio.Queue()]
+    for dlc, queue in zip(dlcs, queues):
+        dlc.sink = queue.put_nowait
+
+    dlcs[0].write(b'The quick brown fox jumps over the lazy dog')
+    assert await queues[1].get() == b'The quick brown fox jumps over the lazy dog'
+
+    dlcs[1].write(b'Lorem ipsum dolor sit amet')
+    assert await queues[0].get() == b'Lorem ipsum dolor sit amet'
+
+
 # -----------------------------------------------------------------------------
 if __name__ == '__main__':
     test_frames()