From d6e7f411518a43bd8bd629a0f1db5ca747319979 Mon Sep 17 00:00:00 2001
From: mattn <mattn.jp@gmail.com>
Date: Sun, 26 Jun 2022 14:26:21 +0900
Subject: [PATCH] cmd/tailscale: make ssh command prefer Windows ssh.exe over
 PATH

use C:\Windows\System32\OpenSSH\ssh.exe (#4933)

Change-Id: Iad73b27b23b746de2c7e994572a54e7e1c370588
Signed-off-by: Yasuhiro Matsumoto <mattn.jp@gmail.com>
(cherry picked from commit 1d04e01d1e62e0f83a24c0e2963c1b74db33c00d)
---
 cmd/tailscale/cli/ssh.go              |  3 +--
 cmd/tailscale/cli/ssh_exec.go         |  5 +++++
 cmd/tailscale/cli/ssh_exec_js.go      |  4 ++++
 cmd/tailscale/cli/ssh_exec_windows.go | 13 +++++++++++++
 4 files changed, 23 insertions(+), 2 deletions(-)

diff --git a/cmd/tailscale/cli/ssh.go b/cmd/tailscale/cli/ssh.go
index 92bd42a10..0db6ebd51 100644
--- a/cmd/tailscale/cli/ssh.go
+++ b/cmd/tailscale/cli/ssh.go
@@ -11,7 +11,6 @@
 	"fmt"
 	"log"
 	"os"
-	"os/exec"
 	"os/user"
 	"path/filepath"
 	"runtime"
@@ -63,7 +62,7 @@ func runSSH(ctx context.Context, args []string) error {
 		hostForSSH = v
 	}
 
-	ssh, err := exec.LookPath("ssh")
+	ssh, err := findSSH()
 	if err != nil {
 		// TODO(bradfitz): use Go's crypto/ssh client instead
 		// of failing. But for now:
diff --git a/cmd/tailscale/cli/ssh_exec.go b/cmd/tailscale/cli/ssh_exec.go
index 02fbde61f..bee4d3242 100644
--- a/cmd/tailscale/cli/ssh_exec.go
+++ b/cmd/tailscale/cli/ssh_exec.go
@@ -10,9 +10,14 @@
 import (
 	"errors"
 	"os"
+	"os/exec"
 	"syscall"
 )
 
+func findSSH() (string, error) {
+	return exec.LookPath("ssh")
+}
+
 func execSSH(ssh string, argv []string) error {
 	if err := syscall.Exec(ssh, argv, os.Environ()); err != nil {
 		return err
diff --git a/cmd/tailscale/cli/ssh_exec_js.go b/cmd/tailscale/cli/ssh_exec_js.go
index bc1a97e7c..3dbbea6a2 100644
--- a/cmd/tailscale/cli/ssh_exec_js.go
+++ b/cmd/tailscale/cli/ssh_exec_js.go
@@ -8,6 +8,10 @@
 	"errors"
 )
 
+func findSSH() (string, error) {
+	return "", errors.New("Not implemented")
+}
+
 func execSSH(ssh string, argv []string) error {
 	return errors.New("Not implemented")
 }
diff --git a/cmd/tailscale/cli/ssh_exec_windows.go b/cmd/tailscale/cli/ssh_exec_windows.go
index 1905fff39..88722734f 100644
--- a/cmd/tailscale/cli/ssh_exec_windows.go
+++ b/cmd/tailscale/cli/ssh_exec_windows.go
@@ -8,8 +8,21 @@
 	"errors"
 	"os"
 	"os/exec"
+	"path/filepath"
 )
 
+func findSSH() (string, error) {
+	// use C:\Windows\System32\OpenSSH\ssh.exe since unexpected behavior
+	// occured with ssh.exe provided by msys2/cygwin and other environments.
+	if systemRoot := os.Getenv("SystemRoot"); systemRoot != "" {
+		exe := filepath.Join(systemRoot, "System32", "OpenSSH", "ssh.exe")
+		if st, err := os.Stat(exe); err == nil && !st.IsDir() {
+			return exe, nil
+		}
+	}
+	return exec.LookPath("ssh")
+}
+
 func execSSH(ssh string, argv []string) error {
 	// Don't use syscall.Exec on Windows, it's not fully implemented.
 	cmd := exec.Command(ssh, argv[1:]...)