feat(gateway): add reasons to close event codes (#881)

Signed-off-by: Snipy7374 <davidecucci07@gmail.com>
Co-authored-by: shiftinv <8530778+shiftinv@users.noreply.github.com>

changelog/873.feature.rst

@@ -0,0 +1 @@
+Adds reasons/descriptions to :exc:`ConnectionClosed` errors.

disnake/errors.py

@@ -224,20 +224,56 @@ class ConnectionClosed(ClientException):
         The shard ID that got closed if applicable.
     """
 
+    # https://discord.com/developers/docs/topics/opcodes-and-status-codes#gateway-gateway-close-event-codes
+    GATEWAY_CLOSE_EVENT_REASONS: Dict[int, str] = {
+        4000: "Unknown error",
+        4001: "Unknown opcode",
+        4002: "Decode error",
+        4003: "Not authenticated",
+        4004: "Authentication failed",
+        4005: "Already authenticated",
+        4007: "Invalid sequence",
+        4008: "Rate limited",
+        4009: "Session timed out",
+        4010: "Invalid Shard",
+        4011: "Sharding required - you are required to shard your connection in order to connect.",
+        4012: "Invalid API version",
+        4013: "Invalid intents",
+        4014: "Disallowed intents - you tried to specify an intent that you have not enabled or are not approved for.",
+    }
+
+    # https://discord.com/developers/docs/topics/opcodes-and-status-codes#voice-voice-close-event-codes
+    GATEWAY_VOICE_CLOSE_EVENT_REASONS: Dict[int, str] = {
+        **GATEWAY_CLOSE_EVENT_REASONS,
+        4002: "Failed to decode payload",
+        4006: "Session no longer valid",
+        4011: "Server not found",
+        4012: "Unknown protocol",
+        4014: "Disconnected, channel was deleted, you were kicked, voice server changed, or the main gateway session was dropped.",
+        4015: "Voice server crashed",
+        4016: "Unknown encryption mode",
+    }
+
     def __init__(
         self,
         socket: ClientWebSocketResponse,
         *,
         shard_id: Optional[int],
         code: Optional[int] = None,
+        voice: bool = False,
     ) -> None:
         # This exception is just the same exception except
         # reconfigured to subclass ClientException for users
         self.code: int = code or socket.close_code or -1
         # aiohttp doesn't seem to consistently provide close reason
-        self.reason: str = ""
+        self.reason: str = self.GATEWAY_CLOSE_EVENT_REASONS.get(self.code, "Unknown reason")
+        if voice:
+            self.reason = self.GATEWAY_VOICE_CLOSE_EVENT_REASONS.get(self.code, "Unknown reason")
+
         self.shard_id: Optional[int] = shard_id
-        super().__init__(f"Shard ID {self.shard_id} WebSocket closed with {self.code}")
+        super().__init__(
+            f"Shard ID {self.shard_id} WebSocket closed with {self.code}: {self.reason}"
+        )
 
 
 class PrivilegedIntentsRequired(ClientException):

disnake/gateway.py

@@ -1076,14 +1076,14 @@ async def poll_event(self) -> None:
             await self.received_message(utils._from_json(msg.data))
         elif msg.type is aiohttp.WSMsgType.ERROR:
             _log.debug("Received %s", msg)
-            raise ConnectionClosed(self.ws, shard_id=None) from msg.data
+            raise ConnectionClosed(self.ws, shard_id=None, voice=True) from msg.data
         elif msg.type in (
             aiohttp.WSMsgType.CLOSED,
             aiohttp.WSMsgType.CLOSE,
             aiohttp.WSMsgType.CLOSING,
         ):
             _log.debug("Received %s", msg)
-            raise ConnectionClosed(self.ws, shard_id=None, code=self._close_code)
+            raise ConnectionClosed(self.ws, shard_id=None, code=self._close_code, voice=True)
 
     async def close(self, code: int = 1000) -> None:
         if self._keep_alive is not None: