Subsystem support

session.go

@@ -44,6 +44,9 @@ type Session interface {
 	// which considers quoting not just whitespace.
 	Command() []string
 
+	// Subsystem returns subsystem name if one was asked for, else empty string.
+	Subsystem() string
+
 	// RawCommand returns the exact command that was provided by the user.
 	RawCommand() string
 
@@ -108,6 +111,7 @@ type session struct {
 	winch     chan Window
 	env       []string
 	ptyCb     PtyCallback
+	subsystem string
 	sessReqCb SessionRequestCallback
 	rawCmd    string
 	ctx       Context
@@ -191,6 +195,10 @@ func (sess *session) Command() []string {
 	return append([]string(nil), cmd...)
 }
 
+func (sess *session) Subsystem() string {
+	return sess.subsystem
+}
+
 func (sess *session) Pty() (Pty, <-chan Window, bool) {
 	if sess.pty != nil {
 		return *sess.pty, sess.winch, true
@@ -235,6 +243,21 @@ func (sess *session) handleRequests(reqs <-chan *gossh.Request) {
 			sess.handled = true
 			req.Reply(true, nil)
 
+			go func() {
+				sess.handler(sess)
+				sess.Exit(0)
+			}()
+		case "subsystem":
+			if sess.handled {
+				req.Reply(false, nil)
+				continue
+			}
+			sess.handled = true
+			req.Reply(true, nil)
+
+			var payload = struct{ Value string }{}
+			gossh.Unmarshal(req.Payload, &payload)
+			sess.subsystem = payload.Value
 			go func() {
 				sess.handler(sess)
 				sess.Exit(0)