From 27f36f77c364562bc1ca660c241291e23606e54d Mon Sep 17 00:00:00 2001
From: Mihai Parparita <mihai@tailscale.com>
Date: Mon, 29 Aug 2022 18:12:52 -0700
Subject: [PATCH] cmd/tsconnect: output errors to the JS console too

We were just outputting them to the terminal, but that's hard to debug
because we immediately tear down the terminal when getting an error.

Signed-off-by: Mihai Parparita <mihai@tailscale.com>
---
 cmd/tsconnect/src/lib/ssh.ts         | 29 ++++++++++++++++++++--------
 cmd/tsconnect/src/types/wasm_js.d.ts |  1 +
 cmd/tsconnect/wasm/wasm_js.go        |  3 ++-
 3 files changed, 24 insertions(+), 9 deletions(-)

diff --git a/cmd/tsconnect/src/lib/ssh.ts b/cmd/tsconnect/src/lib/ssh.ts
index 424687909..c1308b3d5 100644
--- a/cmd/tsconnect/src/lib/ssh.ts
+++ b/cmd/tsconnect/src/lib/ssh.ts
@@ -27,26 +27,39 @@ export function runSSHSession(
 
   term.focus()
 
-  const sshSession = ipn.ssh(def.hostname, def.username, {
-    writeFn: (input) => term.write(input),
-    setReadFn: (hook) => (onDataHook = hook),
+  let resizeObserver: ResizeObserver | undefined
+  let handleBeforeUnload: ((e: BeforeUnloadEvent) => void) | undefined
+
+  const sshSession = ipn.ssh(def.hostname + "2", def.username, {
+    writeFn(input) {
+      term.write(input)
+    },
+    writeErrorFn(err) {
+      console.error(err)
+      term.write(err)
+    },
+    setReadFn(hook) {
+      onDataHook = hook
+    },
     rows: term.rows,
     cols: term.cols,
-    onDone: () => {
-      resizeObserver.disconnect()
+    onDone() {
+      resizeObserver?.disconnect()
       term.dispose()
-      window.removeEventListener("beforeunload", handleBeforeUnload)
+      if (handleBeforeUnload) {
+        window.removeEventListener("beforeunload", handleBeforeUnload)
+      }
       onDone()
     },
   })
 
   // Make terminal and SSH session track the size of the containing DOM node.
-  const resizeObserver = new ResizeObserver(() => fitAddon.fit())
+  resizeObserver = new ResizeObserver(() => fitAddon.fit())
   resizeObserver.observe(termContainerNode)
   term.onResize(({ rows, cols }) => sshSession.resize(rows, cols))
 
   // Close the session if the user closes the window without an explicit
   // exit.
-  const handleBeforeUnload = () => sshSession.close()
+  handleBeforeUnload = () => sshSession.close()
   window.addEventListener("beforeunload", handleBeforeUnload)
 }
diff --git a/cmd/tsconnect/src/types/wasm_js.d.ts b/cmd/tsconnect/src/types/wasm_js.d.ts
index 9d6622a7c..b7ae9c793 100644
--- a/cmd/tsconnect/src/types/wasm_js.d.ts
+++ b/cmd/tsconnect/src/types/wasm_js.d.ts
@@ -19,6 +19,7 @@ declare global {
       username: string,
       termConfig: {
         writeFn: (data: string) => void
+        writeErrorFn: (err: string) => void
         setReadFn: (readFn: (data: string) => void) => void
         rows: number
         cols: number
diff --git a/cmd/tsconnect/wasm/wasm_js.go b/cmd/tsconnect/wasm/wasm_js.go
index 18abef044..e4cf762bf 100644
--- a/cmd/tsconnect/wasm/wasm_js.go
+++ b/cmd/tsconnect/wasm/wasm_js.go
@@ -347,6 +347,7 @@ type jsSSHSession struct {
 
 func (s *jsSSHSession) Run() {
 	writeFn := s.termConfig.Get("writeFn")
+	writeErrorFn := s.termConfig.Get("writeErrorFn")
 	setReadFn := s.termConfig.Get("setReadFn")
 	rows := s.termConfig.Get("rows").Int()
 	cols := s.termConfig.Get("cols").Int()
@@ -357,7 +358,7 @@ func (s *jsSSHSession) Run() {
 		writeFn.Invoke(s)
 	}
 	writeError := func(label string, err error) {
-		write(fmt.Sprintf("%s Error: %v\r\n", label, err))
+		writeErrorFn.Invoke(fmt.Sprintf("%s Error: %v\r\n", label, err))
 	}
 
 	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)