From 6905b9d7682e85b3c56616dc49db74105df2d827 Mon Sep 17 00:00:00 2001
From: Simon Ser <contact@emersion.fr>
Date: Mon, 5 May 2025 18:35:20 +0200
Subject: [PATCH] lib/client: add human-readable messages for WebSocket error
 codes

---
 lib/client.js | 50 +++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 43 insertions(+), 7 deletions(-)

diff --git a/lib/client.js b/lib/client.js
index 1cd5e28..d959630 100644
--- a/lib/client.js
+++ b/lib/client.js
@@ -32,9 +32,33 @@ const RECONNECT_MAX_DELAY_MSEC = 10 * 60 * 1000; // 10min
 
 // WebSocket status codes
 // https://www.rfc-editor.org/rfc/rfc6455.html#section-7.4.1
-const NORMAL_CLOSURE = 1000;
-const GOING_AWAY = 1001;
-const UNSUPPORTED_DATA = 1003;
+const WEBSOCKET_CLOSE_CODES = {
+	NORMAL_CLOSURE: 1000,
+	GOING_AWAY: 1001,
+	PROTOCOL_ERROR: 1002,
+	UNSUPPORTED_DATA: 1003,
+	NO_STATUS_CODE: 1005,
+	ABNORMAL_CLOSURE: 1006,
+	INVALID_FRAME_PAYLOAD_DATA: 1007,
+	POLICY_VIOLATION: 1008,
+	MESSAGE_TOO_BIG: 1009,
+	MISSING_MANDATORY_EXT: 1010,
+	INTERNAL_SERVER_ERROR: 1011,
+	TLS_HANDSHAKE_FAILED: 1015,
+};
+const WEBSOCKET_CLOSE_CODE_NAMES = {
+	[WEBSOCKET_CLOSE_CODES.GOING_AWAY]: "going away",
+	[WEBSOCKET_CLOSE_CODES.PROTOCOL_ERROR]: "protocol error",
+	[WEBSOCKET_CLOSE_CODES.UNSUPPORTED_DATA]: "unsupported data",
+	[WEBSOCKET_CLOSE_CODES.NO_STATUS_CODE]: "no status code received",
+	[WEBSOCKET_CLOSE_CODES.ABNORMAL_CLOSURE]: "abnormal closure",
+	[WEBSOCKET_CLOSE_CODES.INVALID_FRAME_PAYLOAD_DATA]: "invalid frame payload data",
+	[WEBSOCKET_CLOSE_CODES.POLICY_VIOLATION]: "policy violation",
+	[WEBSOCKET_CLOSE_CODES.MESSAGE_TOO_BIG]: "message too big",
+	[WEBSOCKET_CLOSE_CODES.MISSING_MANDATORY_EXT]: "missing mandatory extension",
+	[WEBSOCKET_CLOSE_CODES.INTERNAL_SERVER_ERROR]: "internal server error",
+	[WEBSOCKET_CLOSE_CODES.TLS_HANDSHAKE_FAILED]: "TLS handshake failed",
+};
 
 // See https://github.com/quakenet/snircd/blob/master/doc/readme.who
 // Sorted by order of appearance in RPL_WHOSPCRPL
@@ -69,6 +93,18 @@ class IRCError extends Error {
 	}
 }
 
+class WebSocketError extends Error {
+	constructor(code) {
+		let text = "Connection error";
+		let name = WEBSOCKET_CLOSE_CODE_NAMES[code];
+		if (name) {
+			text += " (" + name + ")";
+		}
+
+		super(text);
+	}
+}
+
 /**
  * Implements a simple exponential backoff.
  */
@@ -189,8 +225,8 @@ export default class Client extends EventTarget {
 		this.ws.addEventListener("close", (event) => {
 			console.log("Connection closed (code: " + event.code + ")");
 
-			if (event.code !== NORMAL_CLOSURE && event.code !== GOING_AWAY) {
-				this.dispatchError(new Error("Connection error"));
+			if (event.code !== WEBSOCKET_CLOSE_CODES.NORMAL_CLOSURE && event.code !== WEBSOCKET_CLOSE_CODES.GOING_AWAY) {
+				this.dispatchError(new WebSocketError(event.code));
 			}
 
 			this.ws = null;
@@ -237,7 +273,7 @@ export default class Client extends EventTarget {
 		this.setPingInterval(0);
 
 		if (this.ws) {
-			this.ws.close(NORMAL_CLOSURE);
+			this.ws.close(WEBSOCKET_CLOSE_CODES.NORMAL_CLOSURE);
 		}
 	}
 
@@ -297,7 +333,7 @@ export default class Client extends EventTarget {
 	handleMessage(event) {
 		if (typeof event.data !== "string") {
 			console.error("Received unsupported data type:", event.data);
-			this.ws.close(UNSUPPORTED_DATA);
+			this.ws.close(WEBSOCKET_CLOSE_CODES.UNSUPPORTED_DATA);
 			return;
 		}