Specific Exceptions: Adapting udp_multicast interface (hardbyte#1089)

* Adjust exceptions in udp_multicast interface

* Format code with black

Author: felixdivo

can/interfaces/udp_multicast/bus.py

@@ -92,7 +92,9 @@ def __init__(
         check_msgpack_installed()
 
         if receive_own_messages:
-            raise NotImplementedError("receiving own messages is not yet implemented")
+            raise can.CanInterfaceNotImplementedError(
+                "receiving own messages is not yet implemented"
+            )
 
         super().__init__(channel, **kwargs)
 
@@ -105,7 +107,14 @@ def _recv_internal(self, timeout: Optional[float]):
             return None, False
 
         data, _, timestamp = result
-        can_message = unpack_message(data, replace={"timestamp": timestamp})
+        try:
+            can_message = unpack_message(
+                data, replace={"timestamp": timestamp}, check=True
+            )
+        except Exception as exception:
+            raise can.CanOperationError(
+                "could not unpack received message"
+            ) from exception
 
         if not self.is_fd and can_message.is_fd:
             return None, False
@@ -114,7 +123,9 @@ def _recv_internal(self, timeout: Optional[float]):
 
     def send(self, message: can.Message, timeout: Optional[float] = None) -> None:
         if not self.is_fd and message.is_fd:
-            raise RuntimeError("cannot send FD message over bus with CAN FD disabled")
+            raise can.CanOperationError(
+                "cannot send FD message over bus with CAN FD disabled"
+            )
 
         data = pack_message(message)
         self._multicast.send(data, timeout)
@@ -149,7 +160,10 @@ def _detect_available_configs() -> List[AutoDetectedConfig]:
 
 
 class GeneralPurposeUdpMulticastBus:
-    """A general purpose send and receive handler for multicast over IP/UDP."""
+    """A general purpose send and receive handler for multicast over IP/UDP.
+
+    However, it raises CAN-specific exceptions for convenience.
+    """
 
     def __init__(
         self, group: str, port: int, hop_limit: int, max_buffer: int = 4096
@@ -178,7 +192,9 @@ def __init__(
         if sock is not None:
             self._socket = sock
         else:
-            raise RuntimeError("could not connect to a multicast IP network")
+            raise can.CanInitializationError(
+                "could not connect to a multicast IP network"
+            )
 
         # used in recv()
         self.received_timestamp_struct = "@ll"
@@ -193,8 +209,10 @@ def _create_socket(self, address_family: socket.AddressFamily) -> socket.socket:
         """Creates a new socket. This might fail and raise an exception!
 
         :param address_family: whether this is of type `socket.AF_INET` or `socket.AF_INET6`
-        :raises OSError: if the socket could not be opened or configured correctly; in this case, it is
-                         guaranteed to be closed/cleaned up
+
+        :raises can.CanInitializationError:
+            if the socket could not be opened or configured correctly; in this case, it is
+            guaranteed to be closed/cleaned up
         """
         # create the UDP socket
         # this might already fail but then there is nothing to clean up
@@ -243,7 +261,9 @@ def _create_socket(self, address_family: socket.AddressFamily) -> socket.socket:
                 log.warning("Could not close partly configured socket: %s", close_error)
 
             # still raise the error
-            raise error
+            raise can.CanInitializationError(
+                "could not create or configure socket"
+            ) from error
 
     def send(self, data: bytes, timeout: Optional[float] = None) -> None:
         """Send data to all group members. This call blocks.
@@ -283,7 +303,9 @@ def recv(
             ready_receive_sockets, _, _ = select.select([self._socket], [], [], timeout)
         except socket.error as exc:
             # something bad (not a timeout) happened (e.g. the interface went down)
-            raise can.CanError(f"Failed to wait for IP/UDP socket: {exc}")
+            raise can.CanOperationError(
+                f"Failed to wait for IP/UDP socket: {exc}"
+            ) from exc
 
         if ready_receive_sockets:  # not empty
             # fetch data & source address

can/interfaces/udp_multicast/utils.py

@@ -7,6 +7,7 @@
 from typing import Optional
 
 from can import Message
+from can import CanInterfaceNotImplementedError
 from can.typechecking import ReadableBytesLike
 
 try:
@@ -16,9 +17,9 @@
 
 
 def check_msgpack_installed() -> None:
-    """Raises a `RuntimeError` if `msgpack` is not installed."""
+    """Raises a :class:`can.CanInterfaceNotImplementedError` if `msgpack` is not installed."""
     if msgpack is None:
-        raise RuntimeError("msgpack not installed")
+        raise CanInterfaceNotImplementedError("msgpack not installed")
 
 
 def pack_message(message: Message) -> bytes: