From 538717cfc9b88b80495004a64674e926659491fa Mon Sep 17 00:00:00 2001
From: hippoz <10706925-hippoz@users.noreply.gitlab.com>
Date: Thu, 14 Apr 2022 21:29:46 +0300
Subject: [PATCH] backend/gateway: block comically large string payloads

---
 src/errors.ts        | 1 +
 src/gateway/index.ts | 7 ++++++-
 2 files changed, 7 insertions(+), 1 deletion(-)

diff --git a/src/errors.ts b/src/errors.ts
index 1e7e259..c2b8000 100644
--- a/src/errors.ts
+++ b/src/errors.ts
@@ -14,4 +14,5 @@ export const gatewayErrors = {
     NO_PING: { code: 4004, message: "No ping" },
     FLOODING: { code: 4005, message: "Flooding (exceeded maximum messages per batch)" },
     ALREADY_AUTHENTICATED: { code: 4006, message: "Already authenticated" },
+    PAYLOAD_TOO_LARGE: { code: 4007, message: "Payload too large" },
 };
diff --git a/src/gateway/index.ts b/src/gateway/index.ts
index a2eb33e..c3e5a5e 100644
--- a/src/gateway/index.ts
+++ b/src/gateway/index.ts
@@ -170,8 +170,13 @@ export default function(server: Server) {
             if (ws.state.messagesSinceLastCheck > MAX_CLIENT_MESSAGES_PER_BATCH) {
                 return closeWithError(ws, gatewayErrors.FLOODING);
             }
+            
+            const stringData = rawData.toString();
+            if (stringData.length > 2048) {
+                return closeWithError(ws, gatewayErrors.PAYLOAD_TOO_LARGE);
+            }
 
-            const payload = ensureFormattedGatewayPayload(parseJsonOrNull(rawData.toString()));
+            const payload = ensureFormattedGatewayPayload(parseJsonOrNull(stringData));
             if (!payload) {
                 return closeWithBadPayload(ws, "Invalid JSON or message does not match schema");
             }