From 219a189993fc30e3b4dc98b27bf1f965a404ec6e Mon Sep 17 00:00:00 2001
From: Sander Declerck <sander@sdsoftware.be>
Date: Wed, 8 Oct 2025 19:32:25 +0200
Subject: [PATCH] Check if a socket is writable before writing to it

---
 .../src/registryProxy/tunnelRequestHandler.js | 20 ++++++++++++++-----
 1 file changed, 15 insertions(+), 5 deletions(-)

diff --git a/packages/safe-chain/src/registryProxy/tunnelRequestHandler.js b/packages/safe-chain/src/registryProxy/tunnelRequestHandler.js
index 95e2beb..fa12aee 100644
--- a/packages/safe-chain/src/registryProxy/tunnelRequestHandler.js
+++ b/packages/safe-chain/src/registryProxy/tunnelRequestHandler.js
@@ -35,7 +35,9 @@ function tunnelRequestToDestination(req, clientSocket, head) {
     ui.writeError(
       `Safe-chain: error connecting to ${hostname}:${port} - ${err.message}`
     );
-    clientSocket.end("HTTP/1.1 502 Bad Gateway\r\n\r\n");
+    if (clientSocket.writable) {
+      clientSocket.end("HTTP/1.1 502 Bad Gateway\r\n\r\n");
+    }
   });
 }
 
@@ -76,8 +78,12 @@ function tunnelRequestViaProxy(req, clientSocket, head, proxyUrl) {
       ui.writeError(
         `Safe-chain: proxy CONNECT failed: ${response.split("\r\n")[0]}`
       );
-      clientSocket.end("HTTP/1.1 502 Bad Gateway\r\n\r\n");
-      proxySocket.end();
+      if (clientSocket.writable) {
+        clientSocket.end("HTTP/1.1 502 Bad Gateway\r\n\r\n");
+      }
+      if (proxySocket.writable) {
+        proxySocket.end();
+      }
     }
   });
 
@@ -88,11 +94,15 @@ function tunnelRequestViaProxy(req, clientSocket, head, proxyUrl) {
           proxy.port || 8080
         } - ${err.message}`
       );
-      clientSocket.end("HTTP/1.1 502 Bad Gateway\r\n\r\n");
+      if (clientSocket.writable) {
+        clientSocket.end("HTTP/1.1 502 Bad Gateway\r\n\r\n");
+      }
     }
   });
 
   clientSocket.on("error", () => {
-    proxySocket.end();
+    if (proxySocket.writable) {
+      proxySocket.end();
+    }
   });
 }