Run remote hosts on Windows over direct SSH

apps/review-desktop/code-oss/src/vs/review/electron-main/remote/reviewRemoteHost.ts

@@ -93,8 +93,12 @@ const SSH_SENTENCES: [RegExp, (alias: string) => string][] = [
 	[/(Operation|Connection) timed out/, (alias) => `The SSH connection to ${alias} timed out. Check that it is on and reachable from this network.`],
 ];
 
-function sshFailureSentence(stderr: string, alias: string): string | undefined {
-	return SSH_SENTENCES.find(([pattern]) => pattern.test(stderr))?.[1](alias);
+/** A direct session cannot prompt, so a key with a passphrase only works through ssh-agent. */
+const DIRECT_PERMISSION_HINT = 'Whiteboard cannot ask for a password or passphrase here: if your key has one, add it to ssh-agent with "ssh-add", then retry.';
+
+function sshFailureSentence(stderr: string, alias: string, direct = false): string | undefined {
+	const sentence = SSH_SENTENCES.find(([pattern]) => pattern.test(stderr))?.[1](alias);
+	return direct && sentence && /Permission denied/.test(stderr) ? `${sentence} ${DIRECT_PERMISSION_HINT}` : sentence;
 }
 
 const SSH_DROPS: [RegExp, (alias: string) => string][] = [
@@ -599,7 +603,7 @@ export class ReviewRemoteHost {
 				detail: sshDropSentence(last, this.alias) ?? `The SSH connection to ${this.alias} ended: ${last || exited}`,
 			});
 		}
-		const sentence = sshFailureSentence(this.masterStderr, this.alias);
+		const sentence = sshFailureSentence(this.masterStderr, this.alias, this.direct);
 		if (sentence) this.options.log(`${this.alias}: ${exited} ${firstLines(this.masterStderr)}`);
 		this.fail({
 			state: classifySshFailure(this.masterStderr, this.promptCancelled),

apps/review-desktop/code-oss/src/vs/review/electron-main/remote/reviewSshCommand.ts

@@ -4,9 +4,10 @@
  *--------------------------------------------------------------------------------------------*/
 
 import { createHash } from "node:crypto";
+import { existsSync } from "node:fs";
 import { chmod, lstat, mkdir } from "node:fs/promises";
 import { homedir, tmpdir } from "node:os";
-import { join } from "node:path";
+import { join, win32 } from "node:path";
 
 import { validateSshAlias } from "../../common/reviewSshAlias.js";
 
@@ -32,6 +33,13 @@ export function reviewSshSharesConnections(env: NodeJS.ProcessEnv = process.env,
 	return platform !== "win32" && !(env.VSCODE_DEV && env[REVIEW_SSH_DIRECT_ENV] === "1");
 }
 
+/** On Windows, the inbox Win32-OpenSSH rather than an MSYS ssh, such as Git for Windows', earlier on PATH. */
+export function reviewSshBinary(env: NodeJS.ProcessEnv = process.env, platform = process.platform, exists = existsSync): string {
+	if (platform !== "win32") return "ssh";
+	const inbox = win32.join(env.SystemRoot ?? "C:\\Windows", "System32", "OpenSSH", "ssh.exe");
+	return exists(inbox) ? inbox : "ssh";
+}
+
 /** Connection sharing needs Unix sockets and a uid; Windows has neither. */
 function currentUid(): number {
 	if (!process.getuid) throw new Error("SSH connection sharing is not supported on this platform.");

apps/review-desktop/code-oss/src/vs/review/electron-main/remote/reviewSshConfigAliases.ts

@@ -54,7 +54,8 @@ async function expand(pattern: string, includeDir: string): Promise<string[]> {
 	const path = pattern.startsWith("~/") ? join(homedir(), pattern.slice(2)) : isAbsolute(pattern) ? pattern : join(includeDir, pattern);
 	const files: string[] = [];
 	try {
-		for await (const file of glob(path)) files.push(file);
+		// A glob pattern escapes with backslashes; Windows paths take forward slashes too.
+		for await (const file of glob(process.platform === "win32" ? path.replaceAll("\\", "/") : path)) files.push(file);
 	} catch {
 		return [];
 	}

apps/review-desktop/code-oss/src/vs/review/electron-main/reviewDesktopHost.ts

@@ -63,6 +63,7 @@ import { installRemote } from "./remote/reviewRemoteInstaller.js";
 import { readRemoteInstallScript } from "./remote/reviewRemoteInstallScript.js";
 import { createSshAskpass } from "./remote/reviewSshAskpass.js";
 import {
+  reviewSshBinary,
   reviewSshConfigPath,
   reviewSshControlDirectory,
   reviewSshSharesConnections,
@@ -357,11 +358,19 @@ export class ReviewDesktopHost extends Disposable {
   private startRemoteHosts(
     shellEnvironment: () => Promise<NodeJS.ProcessEnv>,
   ): void {
-    // SSH hosts need ControlMaster sockets, which Windows OpenSSH lacks.
-    if (this.disposed || process.platform === "win32") return;
+    if (this.disposed) return;
     let version: Promise<string> | undefined;
+    const ssh = reviewSshBinary();
     const manager = new ReviewRemoteHosts({
-      spawn: (args, options) => spawn("ssh", args, options),
+      // A detached ssh gets a console window on Windows; direct sessions never prompt there.
+      spawn: (args, options) =>
+        spawn(
+          ssh,
+          args,
+          process.platform === "win32"
+            ? { ...options, detached: false, windowsHide: true }
+            : options,
+        ),
       controlDirectory: reviewSshSharesConnections()
         ? reviewSshControlDirectory()
         : undefined,

docs/remote-hosts.md

@@ -27,8 +27,20 @@ config apply to Whiteboard's connections too.
 - An OpenSSH server that allows TCP forwarding. See
   [TCP forwarding](#tcp-forwarding).
 
-Your laptop needs macOS or Linux with the OpenSSH client. A Windows laptop is
-not supported yet.
+Your laptop needs the OpenSSH client. On Windows, that is the built-in
+OpenSSH Client, with two limits:
+
+- Whiteboard cannot show SSH prompts there. Use a key without a passphrase, or
+  load it into the `ssh-agent` service:
+
+  ```powershell
+  Get-Service ssh-agent | Set-Service -StartupType Automatic -PassThru | Start-Service
+  ssh-add
+  ```
+
+- Run `ssh <alias>` once in a terminal to verify and accept the host's key.
+
+Each command Desktop runs on a Windows laptop opens its own SSH connection.
 
 ## Add a host
 
@@ -50,8 +62,8 @@ remote is deleted unless you check
 The hosts are kept in the setting `review.remote.hosts`, a list of aliases.
 Only you can change it: a repository or a remote never adds a host.
 
-If `ssh` asks for a password, a passphrase or a host key confirmation,
-Whiteboard shows the prompt in its window. Your answer goes to `ssh` and is
+On macOS and Linux, if `ssh` asks for a password, a passphrase or a host key
+confirmation, Whiteboard shows the prompt in its window. Your answer goes to `ssh` and is
 never stored.
 
 ## How Desktop installs Whiteboard