close proxied websockets when upstream sends a regular response

Author: minrk

lib/configproxy.js

@@ -176,6 +176,24 @@ export class ConfigurableProxy extends EventEmitter {
     }
     options.ws = true;
     this.proxy = httpProxy.createProxyServer(options);
+    this.proxy.on("proxyReqWs", (proxyReq, req, socket, options, head) => {
+      proxyReq.on("response", (res) => {
+        that.log.info(
+          "Client requested websocket at %s, proxy target %s responded with HTTP %s %s",
+          req.url,
+          proxyReq.host,
+          res.statusCode,
+          res.statusMessage
+        );
+        if (!socket.destroyed) {
+          socket.write(
+            `HTTP/1.1 ${res.statusCode} Upstream not a websocket\r\nConnection: close\r\n\r\n`
+          );
+          socket.end();
+        }
+        res.resume();
+      });
+    });
 
     // tornado-style regex routing,
     // because cross-language cargo-culting is always a good idea