Merge pull request #92 from glassechidna/master

Added Server.KeyboardInteractiveHandler

Author: belak

server.go

@@ -24,6 +24,7 @@ type Server struct {
 	HostSigners []Signer // private keys for the host key, must have at least one
 	Version     string   // server version to be sent before the initial handshake
 
+	KeyboardInteractiveHandler    KeyboardInteractiveHandler    // keyboard-interactive authentication handler
 	PasswordHandler               PasswordHandler               // password authentication handler
 	PublicKeyHandler              PublicKeyHandler              // public key authentication handler
 	PtyCallback                   PtyCallback                   // callback for allowing PTY sessions, allows all if nil
@@ -105,6 +106,14 @@ func (srv *Server) config(ctx Context) *gossh.ServerConfig {
 			return ctx.Permissions().Permissions, nil
 		}
 	}
+	if srv.KeyboardInteractiveHandler != nil {
+		config.KeyboardInteractiveCallback = func(conn gossh.ConnMetadata, challenger gossh.KeyboardInteractiveChallenge) (*gossh.Permissions, error) {
+			if ok := srv.KeyboardInteractiveHandler(ctx, challenger); !ok {
+				return ctx.Permissions().Permissions, fmt.Errorf("permission denied")
+			}
+			return ctx.Permissions().Permissions, nil
+		}
+	}
 	return config
 }
 

ssh.go

@@ -2,6 +2,7 @@ package ssh
 
 import (
 	"crypto/subtle"
+	gossh "golang.org/x/crypto/ssh"
 	"net"
 )
 
@@ -39,6 +40,9 @@ type PublicKeyHandler func(ctx Context, key PublicKey) bool
 // PasswordHandler is a callback for performing password authentication.
 type PasswordHandler func(ctx Context, password string) bool
 
+// KeyboardInteractiveHandler is a callback for performing keyboard-interactive authentication.
+type KeyboardInteractiveHandler func(ctx Context, challenger gossh.KeyboardInteractiveChallenge) bool
+
 // PtyCallback is a hook for allowing PTY sessions.
 type PtyCallback func(ctx Context, pty Pty) bool