Further work on term resizing platform support for Linux and Windows/mintty

hkexsh/hkexsh.go

@@ -32,19 +32,21 @@ type cmdSpec struct {
 	status     int
 }
 
-// get terminal size using 'stty' command
-// (Most portable btwn Linux and MSYS/win32, but
-//  TODO: remove external dep on 'stty' utility)
-func getTermSize() (rows int, cols int, err error) {
+var (
+	wg sync.WaitGroup
+)
+
+// Get terminal size using 'stty' command
+func GetSize() (cols, rows int, err error) {
 	cmd := exec.Command("stty", "size")
 	cmd.Stdin = os.Stdin
 	out, err := cmd.Output()
-	//fmt.Printf("out: %#v\n", string(out))
-	//fmt.Printf("err: %#v\n", err)
 
-	fmt.Sscanf(string(out), "%d %d\n", &rows, &cols)
 	if err != nil {
-		log.Fatal(err)
+		log.Println(err)
+		cols, rows = 80, 24  //failsafe
+	} else {
+		fmt.Sscanf(string(out), "%d %d\n", &rows, &cols)
 	}
 	return
 }
@@ -62,8 +64,6 @@ func getTermSize() (rows int, cols int, err error) {
 // connection (app-specific, passed through to the server to use or
 // ignore at its discretion).
 func main() {
-	var wg sync.WaitGroup
-
 	version := "0.1pre (NO WARRANTY)"
 	var vopt bool
 	var dbg bool
@@ -73,6 +73,7 @@ func main() {
 	var cmdStr string
 	var altUser string
 	var authCookie string
+	var chaffEnabled bool
 	var chaffFreqMin uint
 	var chaffFreqMax uint
 	var chaffBytesMax uint
@@ -86,6 +87,7 @@ func main() {
 	flag.StringVar(&cmdStr, "x", "", "command to run (default empty - interactive shell)")
 	flag.StringVar(&altUser, "u", "", "specify alternate user")
 	flag.StringVar(&authCookie, "a", "", "auth cookie")
+	flag.BoolVar(&chaffEnabled, "cE", true, "enabled chaff pkts (default true)")
 	flag.UintVar(&chaffFreqMin, "cfm", 100, "chaff pkt freq min (msecs)")
 	flag.UintVar(&chaffFreqMax, "cfM", 5000, "chaff pkt freq max (msecs)")
 	flag.UintVar(&chaffBytesMax, "cbM", 64, "chaff pkt size max (bytes)")
@@ -183,7 +185,9 @@ func main() {
 
 	// Set up chaffing to server
 	conn.Chaff(chaffFreqMin, chaffFreqMax, chaffBytesMax) // enable client->server chaffing
-	conn.EnableChaff()
+	if chaffEnabled {
+		conn.EnableChaff()
+	}
 
 	//client reader (from server) goroutine
 	wg.Add(1)
@@ -218,7 +222,7 @@ func main() {
 	}()
 
 	if isInteractive {
-		handleTermResizes()
+		handleTermResizes(conn)
 
 		// client writer (to server) goroutine
 		wg.Add(1)

hkexsh/termsize_linux.go

@@ -12,7 +12,7 @@ import (
 )
 
 // Handle pty resizes (notify server side)
-func handleTermResizes() {
+func handleTermResizes(conn *hkexsh.Conn) {
 	rows := 0
 	cols := 0
 
@@ -25,10 +25,10 @@ func handleTermResizes() {
 		for range ch {
 			// Query client's term size so we can communicate it to server
 			// pty after interactive session starts
-			rows, cols, err = getTermSize()
+			cols, rows, err = GetSize()
 			log.Printf("[rows %v cols %v]\n", rows, cols)
 			if err != nil {
-				panic(err)
+				log.Println(err)
 			}
 			termSzPacket := fmt.Sprintf("%d %d", rows, cols)
 			conn.WritePacket([]byte(termSzPacket), hkexsh.CSOTermSize)

hkexsh/termsize_win.go

@@ -1,8 +1,65 @@
 // +build windows
 package main
 
+import (
+	"fmt"
+	"log"
+	"time"
+
+	hkexsh "blitter.com/go/hkexsh"
+)
+
 // Handle pty resizes (notify server side)
-func handleTermResizes() {
+func handleTermResizes(conn *hkexsh.Conn) {
+	var hasStty bool
+	curCols, curRows := 0, 0
+	_, _, err := GetSize()
+	// The above may fail if user doesn't have msys 'stty' util
+	// in PATH. GetSize() will log.Error() once here
+	if err != nil {
+		fmt.Println("[1st GetSize:", err, "]")
+		hasStty = false
+	} else {
+		hasStty = true
+	}
+
+	ch := make(chan bool, 1)
+
+	if hasStty {
+		wg.Add(1)
+		go func() {
+			defer wg.Done()
+			for {
+				ch <- true
+				time.Sleep(1 * time.Second)
+			}
+		}()
+	}
+
+	wg.Add(1)
+	go func() {
+		defer wg.Done()
+
+		rows := 0
+		cols := 0
+		for range ch {
+			// Query client's term size so we can communicate it to server
+			// pty after interactive session starts
+			cols, rows, err = GetSize()
+			if err == nil {
+			} else {
+				fmt.Println("[GetSize:", err, "]")
+			}
+			if (curRows != rows) || (curCols != curCols) {
+				curRows = rows
+				curCols = cols
+				if err != nil {
+					log.Println(err)
+				}
+				termSzPacket := fmt.Sprintf("%d %d", curRows, curCols)
+				conn.WritePacket([]byte(termSzPacket), hkexsh.CSOTermSize)
+			}
+		}
+	}()
+	ch <- true // Initial resize
 }
-
-

hkexshd/hkexshd.go

@@ -79,7 +79,7 @@ func runCmdAs(who string, cmd string, conn hkex.Conn) (err error) {
 // Run a command (via default shell) as a specific user
 //
 // Uses ptys to support commands which expect a terminal.
-func runShellAs(who string, cmd string, interactive bool, conn hkexsh.Conn) (err error) {
+func runShellAs(who string, cmd string, interactive bool, conn hkexsh.Conn, chaffing bool) (err error) {
 	u, _ := user.Lookup(who)
 	var uid, gid uint32
 	fmt.Sscanf(u.Uid, "%d", &uid)
@@ -134,8 +134,10 @@ func runShellAs(who string, cmd string, interactive bool, conn hkexsh.Conn) (err
 		_, _ = io.Copy(ptmx, conn)
 	}()
 
-	conn.EnableChaff()
-
+	if chaffing {
+		conn.EnableChaff()
+	}
+	
 	// ..and the pty to stdout.
 	_, _ = io.Copy(conn, ptmx)
 
@@ -160,6 +162,7 @@ func rejectUserMsg() string {
 func main() {
 	version := "0.1pre (NO WARRANTY)"
 	var vopt bool
+	var chaffEnabled bool
 	var chaffFreqMin uint
 	var chaffFreqMax uint
 	var chaffBytesMax uint
@@ -168,6 +171,7 @@ func main() {
 
 	flag.BoolVar(&vopt, "v", false, "show version")
 	flag.StringVar(&laddr, "l", ":2000", "interface[:port] to listen")
+	flag.BoolVar(&chaffEnabled, "cE", true, "enabled chaff pkts (default true)")
 	flag.UintVar(&chaffFreqMin, "cfm", 100, "chaff pkt freq min (msecs)")
 	flag.UintVar(&chaffFreqMax, "cfM", 5000, "chaff pkt freq max (msecs)")
 	flag.UintVar(&chaffBytesMax, "cbM", 64, "chaff pkt size max (bytes)")
@@ -175,7 +179,7 @@ func main() {
 	flag.Parse()
 
 	if vopt {
-		fmt.Printf("version v%s\n",  version)
+		fmt.Printf("version v%s\n", version)
 		os.Exit(0)
 	}
 
@@ -205,7 +209,9 @@ func main() {
 			log.Println("Accepted client")
 
 			// Set up chaffing to client
-			conn.Chaff(chaffFreqMin, chaffFreqMax, chaffBytesMax) // enable client->server chaffing
+			// Will only start when runShellAs() is called
+			// after stdin/stdout are hooked up
+			conn.Chaff(chaffFreqMin, chaffFreqMax, chaffBytesMax) // configure server->client chaffing
 
 			// Handle the connection in a new goroutine.
 			// The loop then returns to accepting, so that
@@ -276,14 +282,14 @@ func main() {
 				if rec.op[0] == 'c' {
 					// Non-interactive command
 					log.Println("[Running command]")
-					runShellAs(string(rec.who), string(rec.cmd), false, conn)
+					runShellAs(string(rec.who), string(rec.cmd), false, conn, chaffEnabled)
 					// Returned hopefully via an EOF or exit/logout;
 					// Clear current op so user can enter next, or EOF
 					rec.op[0] = 0
 					log.Println("[Command complete]")
 				} else if rec.op[0] == 's' {
 					log.Println("[Running shell]")
-					runShellAs(string(rec.who), string(rec.cmd), true, conn)
+					runShellAs(string(rec.who), string(rec.cmd), true, conn, chaffEnabled)
 					// Returned hopefully via an EOF or exit/logout;
 					// Clear current op so user can enter next, or EOF
 					rec.op[0] = 0