add ssh tunnel

pkg/dialer/ssh/conn.go

@@ -0,0 +1,31 @@
+package ssh
+
+import (
+	"net"
+
+	"golang.org/x/crypto/ssh"
+)
+
+type sshSession struct {
+	addr   string
+	conn   net.Conn
+	client *ssh.Client
+	closed chan struct{}
+	dead   chan struct{}
+}
+
+func (s *sshSession) IsClosed() bool {
+	select {
+	case <-s.dead:
+		return true
+	case <-s.closed:
+		return true
+	default:
+	}
+	return false
+}
+
+func (s *sshSession) wait() error {
+	defer close(s.closed)
+	return s.client.Wait()
+}