server: add sftp support

.gitignore

@@ -1 +1,2 @@
 *~
+*.swp

server.go

@@ -2,9 +2,8 @@ package obfssh
 
 import (
 	"fmt"
+	"github.com/pkg/sftp"
 	"golang.org/x/crypto/ssh"
-	"golang.org/x/crypto/ssh/terminal"
-	//"log"
 	"net"
 )
 
@@ -73,22 +72,30 @@ func (sc *Server) close() {
 
 func (sc *Server) handleNewChannelRequest(ch <-chan ssh.NewChannel) {
 	for newch := range ch {
+
+		Log(DEBUG, "request channel %s", newch.ChannelType())
+
 		switch newch.ChannelType() {
 		case "session":
-			//go sc.handleSession(newch)
-			//continue
+			go sc.handleSession(newch)
+			continue
+
 		case "direct-tcpip":
 			go handleDirectTcpip(newch)
 			continue
 		}
+
 		Log(DEBUG, "reject channel request %s", newch.ChannelType())
+
 		newch.Reject(ssh.UnknownChannelType, "unknown channel type")
-		//channel, request, err := newch.Accept()
 	}
 }
 
 func (sc *Server) handleGlobalRequest(req <-chan *ssh.Request) {
 	for r := range req {
+
+		Log(DEBUG, "global request %s", r.Type)
+
 		switch r.Type {
 		case "tcpip-forward":
 			Log(DEBUG, "request port forward")
@@ -99,32 +106,26 @@ func (sc *Server) handleGlobalRequest(req <-chan *ssh.Request) {
 			go sc.handleCancelTcpipForward(r)
 			continue
 		}
-		Log(DEBUG, "global request %s", r.Type)
+
 		if r.WantReply {
 			r.Reply(false, nil)
 		}
 	}
 }
 
-func (sc *Server) handleChannelRequest(req <-chan *ssh.Request) {
-	ret := false
-	for r := range req {
-		switch r.Type {
-		case "shell":
-			ret = true
-		case "pty-req":
-			ret = true
-		case "env":
-			ret = true
-		case "exec":
-			ret = false
-		case "subsystem":
-		default:
-			ret = false
-		}
-		if r.WantReply {
-			r.Reply(ret, nil)
+func serveSFTP(ch ssh.Channel) {
+	defer ch.Close()
+
+	server, err := sftp.NewServer(ch)
+
+	if err != nil {
+		Log(DEBUG, "start sftp server failed: %s", err)
+		return
 	}
+
+	if err := server.Serve(); err != nil {
+		Log(DEBUG, "sftp server finished with error: %s", err)
+		return
 	}
 }
 
@@ -135,49 +136,81 @@ type directTcpipMsg struct {
 	Lport uint32
 }
 
+type args struct {
+	Arg string
+}
+
 func (sc *Server) handleSession(newch ssh.NewChannel) {
 	ch, req, err := newch.Accept()
 	if err != nil {
 		Log(ERROR, "%s", err.Error())
 		return
 	}
-	go sc.handleChannelRequest(req)
-	term := terminal.NewTerminal(ch, "shell>")
-	defer ch.Close()
-	for {
-		line, err := term.ReadLine()
-		if err != nil {
-			break
+
+	var cmd args
+
+	ret := false
+
+	for r := range req {
+		switch r.Type {
+		case "subsystem":
+			if err := ssh.Unmarshal(r.Payload, &cmd); err != nil {
+				ret = false
+			} else {
+				if cmd.Arg != "sftp" { // only support sftp
+					ret = false
+				} else {
+
+					ret = true
+
+					Log(DEBUG, "handle sftp request")
+
+					go serveSFTP(ch)
+				}
+			}
+		default:
+			ret = false
+		}
+
+		Log(DEBUG, "session request %s, reply %q", r.Type, ret)
+
+		if r.WantReply {
+			r.Reply(ret, nil)
 		}
-		term.Write([]byte(line))
-		term.Write([]byte("\n"))
 	}
 }
 
 func handleDirectTcpip(newch ssh.NewChannel) {
-	data := newch.ExtraData()
 	var r directTcpipMsg
+
+	data := newch.ExtraData()
+
 	err := ssh.Unmarshal(data, &r)
 	if err != nil {
 		Log(DEBUG, "invalid ssh parameter")
 		newch.Reject(ssh.ConnectionFailed, "invalid argument")
 		return
 	}
+
 	Log(DEBUG, "create connection to %s:%d", r.Raddr, r.Rport)
+
 	rconn, err := net.Dial("tcp", fmt.Sprintf("%s:%d", r.Raddr, r.Rport))
 	if err != nil {
 		Log(ERROR, "%s", err.Error())
 		newch.Reject(ssh.ConnectionFailed, "invalid argument")
 		return
 	}
+
 	channel, requests, err := newch.Accept()
 	if err != nil {
 		rconn.Close()
 		Log(ERROR, "%s", err.Error())
 		return
 	}
+
 	//log.Println("forward")
 	go ssh.DiscardRequests(requests)
+
 	PipeAndClose(channel, rconn)
 }