From b33e9de139ac9482b8518df47c4ee4ac234d33db Mon Sep 17 00:00:00 2001
From: Russ Magee <rmagee@gmail.com>
Date: Thu, 6 Sep 2018 16:23:57 -0700
Subject: [PATCH] -Moved taunting of failed logins to client-side -Added byte
 auth pass/fail stage prior to shell/copy session start

---
 hkexnet/hkexnet.go |  2 +-
 hkexsh/hkexsh.go   | 58 +++++++++++++++++++++++++---------------------
 hkexshd/hkexshd.go | 21 +++++------------
 3 files changed, 39 insertions(+), 42 deletions(-)

diff --git a/hkexnet/hkexnet.go b/hkexnet/hkexnet.go
index f88e5d8..15dedd4 100644
--- a/hkexnet/hkexnet.go
+++ b/hkexnet/hkexnet.go
@@ -37,7 +37,7 @@ import (
 // const CSExtendedCode - extended (>255 UNIX exit status) codes
 // This indicate channel-related or internal errors
 const (
-	CSEBadAuth     = 1024 // failed login
+	CSEBadAuth     = 1024 // Failed login password
 	CSETruncCSO           // No CSOExitStatus in payload
 	CSEStillOpen          // Channel closed unexpectedly
 	CSEExecFail           // cmd.Start() (exec) failed
diff --git a/hkexsh/hkexsh.go b/hkexsh/hkexsh.go
index 1e04624..4e42f86 100755
--- a/hkexsh/hkexsh.go
+++ b/hkexsh/hkexsh.go
@@ -27,6 +27,7 @@ import (
 
 	hkexsh "blitter.com/go/hkexsh"
 	"blitter.com/go/hkexsh/hkexnet"
+	"blitter.com/go/hkexsh/spinsult"
 	isatty "github.com/mattn/go-isatty"
 )
 
@@ -163,7 +164,7 @@ func doCopyMode(conn *hkexnet.Conn, remoteDest bool, files string, rec *cmdSpec)
 					// an ExitStatus() method with the same signature.
 					if status, ok := exiterr.Sys().(syscall.WaitStatus); ok {
 						exitStatus = uint32(status.ExitStatus())
-						log.Printf("Exit Status: %d", exitStatus)
+						log.Printf("Exit Status: %d", exitStatus) //#
 						fmt.Print(stdErrBuffer)
 					}
 				}
@@ -285,9 +286,9 @@ func doShellMode(isInteractive bool, conn *hkexnet.Conn, oldState *hkexsh.State,
 				log.Println(outerr)
 				fmt.Println(outerr)
 				_ = hkexsh.Restore(int(os.Stdin.Fd()), oldState) // Best effort.
-				os.Exit(254)
+				log.Println("[Hanging up]")
+				os.Exit(0)
 			}
-			log.Println("[Sent EOF]")
 		}()
 	}
 
@@ -309,6 +310,10 @@ func UsageCp() {
 	flag.PrintDefaults()
 }
 
+func rejectUserMsg() string {
+	return "Begone, " + spinsult.GetSentence() + "\r\n"
+}
+
 // hkexsh - a client for secure shell and file copy operations.
 //
 // While conforming to the basic net.Conn interface HKex.Conn has extra
@@ -533,34 +538,35 @@ func main() {
 	_, err = conn.Write(rec.cmd)
 	_, err = conn.Write(rec.authCookie)
 
-	// Set up chaffing to server
-	conn.SetupChaff(chaffFreqMin, chaffFreqMax, chaffBytesMax) // enable client->server chaffing
-	if chaffEnabled {
-		conn.EnableChaff()
-		defer conn.DisableChaff()
-		defer conn.ShutdownChaff()
-	}
-
-	if shellMode {
-		doShellMode(isInteractive, conn, oldState, rec)
+	// Read auth reply from server
+	authReply := make([]byte, 1) // bool: 0 = fail, 1 = pass
+	_, err = conn.Read(authReply)
+	if authReply[0] == 0 {
+		fmt.Fprintln(os.Stderr, rejectUserMsg())
+		rec.status = 255
 	} else {
-		_, rec.status = doCopyMode(conn, pathIsDest, fileArgs, rec)
+
+		// Set up chaffing to server
+		conn.SetupChaff(chaffFreqMin, chaffFreqMax, chaffBytesMax) // enable client->server chaffing
+		if chaffEnabled {
+			conn.EnableChaff()
+			defer conn.DisableChaff()
+			defer conn.ShutdownChaff()
+		}
+
+		if shellMode {
+			doShellMode(isInteractive, conn, oldState, rec)
+		} else { // copyMode
+			_, rec.status = doCopyMode(conn, pathIsDest, fileArgs, rec)
+		}
+		
+		if rec.status != 0 {
+			fmt.Fprintln(os.Stderr, "Remote end exited with status:", rec.status)
+		}
 	}
 
 	if oldState != nil {
 		_ = hkexsh.Restore(int(os.Stdin.Fd()), oldState) // Best effort.
 	}
-
-	if rec.status != 0 {
-		fmt.Fprint(os.Stderr, "Remote end ")
-		if rec.status == hkexnet.CSEBadAuth {
-				// shell exit status can't hold CSEBadAuth (uint32)
-				rec.status = 255
-				fmt.Fprintln(os.Stderr, "replied: bad auth")
-		} else {
-			fmt.Fprintln(os.Stderr, "exited with status:", rec.status)
-		}
-
-	}
 	os.Exit(int(rec.status))
 }
diff --git a/hkexshd/hkexshd.go b/hkexshd/hkexshd.go
index b9c8000..aa26764 100755
--- a/hkexshd/hkexshd.go
+++ b/hkexshd/hkexshd.go
@@ -27,7 +27,6 @@ import (
 	"blitter.com/go/goutmp"
 	hkexsh "blitter.com/go/hkexsh"
 	"blitter.com/go/hkexsh/hkexnet"
-	"blitter.com/go/hkexsh/spinsult"
 	"github.com/kr/pty"
 )
 
@@ -324,10 +323,6 @@ func runShellAs(who string, cmd string, interactive bool, conn hkexnet.Conn, cha
 	return
 }
 
-func rejectUserMsg() string {
-	return "Begone, " + spinsult.GetSentence() + "\r\n"
-}
-
 // Demo of a simple server that listens and spawns goroutines for each
 // connecting client. Note this code is identical to standard tcp
 // server code, save for declaring 'hkex' rather than 'net'
@@ -454,19 +449,15 @@ func main() {
 				}
 				runtime.GC()
 
-				if !valid {
+				// Tell client if auth was valid
+				if valid {
+					hc.Write([]byte{1})
+				} else {
 					log.Println("Invalid user", string(rec.who))
-
-					// Signal other end auth failed
-					rec.status = hkexnet.CSEBadAuth
-					hc.SetStatus(hkexnet.CSEBadAuth)
-					s := make([]byte, 4)
-					binary.BigEndian.PutUint32(s, hkexnet.CSEBadAuth)
-					hc.WritePacket(s, hkexnet.CSOExitStatus)
-
-					hc.Write([]byte(rejectUserMsg()))
+					hc.Write([]byte{0})
 					return
 				}
+
 				log.Printf("[allowedCmds:%s]\n", allowedCmds)
 
 				if rec.op[0] == 'c' {