Monkeypatch SocketWrapper, to survive but report if we do hit the WS bug

Hopefully this'll be fixed by the WS changes, but if not, this ensures
we handle issues cleanly and can keep track of them. Hopefully later on
we'll be able to remove this, if it never triggers.

Author: pimterry

custom-typings/node-extensions.d.ts

@@ -0,0 +1,13 @@
+// Undocumented module that allows us to turn a stream into a usable net.Socket.
+// Deprecated in Node 12+, but useful in the meantime.
+declare module "_stream_wrap" {
+    import * as net from 'net';
+    import * as streams from 'stream';
+
+    class SocketWrapper extends net.Socket {
+        constructor(stream: streams.Duplex);
+        stream?: streams.Duplex & Partial<net.Socket>;
+    }
+
+    export = SocketWrapper;
+}

src/index.ts

@@ -127,3 +127,35 @@ export async function runHTK(options: {
     console.log('Server started in', Date.now() - certSetupTime, 'ms');
     console.log('Total startup took', Date.now() - startTime, 'ms');
 }
+
+import SocketWrapper = require('_stream_wrap');
+
+// Quick monkey-patches to guard against a bug in SocketWrapper that can break
+// some of the Mockttp internals in certain WS-based cases:
+const originalFinishShutdown = (<any>SocketWrapper.prototype).finishShutdown;
+(<any>SocketWrapper.prototype).finishShutdown = function (handle: any) {
+    if (!handle) {
+        // We still run the code anyway (since there are cases where it
+        // might be fine, and we can't check them externally), but we
+        // report issues, so we can work out how widespread this is.
+        try {
+            return originalFinishShutdown.apply(this, arguments);
+        } catch (e) {
+            reportError(e);
+            return;
+        }
+    }
+    else return originalFinishShutdown.apply(this, arguments);
+}
+const originalFinishWrite = (<any>SocketWrapper.prototype).finishWrite;
+(<any>SocketWrapper.prototype).finishWrite = function (handle: any) {
+    if (!handle) {
+        try {
+            return originalFinishWrite.apply(this, arguments);
+        } catch (e) {
+            reportError(e);
+            return;
+        }
+    }
+    else return originalFinishWrite.apply(this, arguments);
+}