cmd/tsconnect: enable web links addon in the terminal

More user friendly, and as a side-effect we handle SSH check mode better,
since the URL that's output is now clickable.

Fixes #5247

Signed-off-by: Mihai Parparita <mihai@tailscale.com>

cmd/tsconnect/src/app/app.tsx

@@ -92,6 +92,12 @@ class App extends Component<{}, AppState> {
   }
 
   handleBrowseToURL = (url: string) => {
+    if (this.state.ipnState === "Running") {
+      // Ignore URL requests if we're already running -- it's most likely an
+      // SSH check mode trigger and we already linkify the displayed URL
+      // in the terminal.
+      return
+    }
     this.setState({ browseToURL: url })
   }
 

cmd/tsconnect/src/lib/ssh.ts

@@ -1,5 +1,6 @@
 import { Terminal } from "xterm"
 import { FitAddon } from "xterm-addon-fit"
+import { WebLinksAddon } from "xterm-addon-web-links"
 
 export type SSHSessionDef = {
   username: string
@@ -14,12 +15,17 @@ export function runSSHSession(
 ) {
   const term = new Terminal({
     cursorBlink: true,
+    allowProposedApi: true,
   })
+
   const fitAddon = new FitAddon()
   term.loadAddon(fitAddon)
   term.open(termContainerNode)
   fitAddon.fit()
 
+  const webLinksAddon = new WebLinksAddon()
+  term.loadAddon(webLinksAddon)
+
   let onDataHook: ((data: string) => void) | undefined
   term.onData((e) => {
     onDataHook?.(e)