New command 'auth' for password protection

src/comm.c

@@ -45,6 +45,7 @@ struct comm comms[RC_LAST + 1] =
   { "allpartial",	NEED_DISPLAY|ARGS_1,		{NULL} },
   { "altscreen",	ARGS_01,			{NULL} },
   { "at",		ARGS_2|ARGS_ORMORE,		{NULL} },
+  { "auth",		ARGS_1,                         {NULL} },
   { "autodetach",	ARGS_1,				{NULL} },
   { "autonuke",		NEED_DISPLAY|ARGS_1,		{NULL} },
   { "backtick",		ARGS_1|ARGS_ORMORE,		{NULL} },

src/doc/screen.1

@@ -1015,6 +1015,14 @@ attrcolor i "+b"
 Make bright colored text also bold.
 .RE
 .TP
+.BR "auth [ on | off ]"
+.RS 0
+.PP
+This command enables/disables password protection for the
+.I screen
+session. It is off by default (authentication is disabled).
+.RE
+.TP
 .BR "autodetach [ on | off ]"
 .RS 0
 .PP

src/doc/screen.texinfo

@@ -887,6 +887,9 @@ Enables support for the "alternate screen" terminal capability.  @xref{Redisplay
 Execute a command at other displays or windows.  @xref{At}.
 @item attrcolor @var{attrib} [@var{attribute/color-modifier}]
 Map attributes to colors.  @xref{Attrcolor}.
+@item auth @var{state}
+This command enables/disables password protection for the screen session.
+It is off by default (authentication is disabled).
 @item autodetach @var{state}
 Automatically detach the session on SIGHUP.  @xref{Detach}.
 @item autonuke @var{state}

src/process.c

@@ -4296,6 +4296,17 @@ static void DoCommandAltscreen(struct action *act)
 		OutputMsg(0, "Will %sdo alternate screen switching", use_altscreen ? "" : "not ");
 }
 
+
+static void DoCommandAuth(struct action *act)
+{
+        int msgok = display && !*rc_name;
+
+        (void)ParseSwitch(act, &do_auth);
+        if (msgok)
+                OutputMsg(0, "Authentication: %s" , do_auth ? "enabled" : "disabled");
+}
+
+
 static void DoCommandBacktick(struct action *act)
 {
 	char **args = act->args;
@@ -5229,6 +5240,9 @@ void DoAction(struct action *act)
 	case RC_ALTSCREEN:
 		DoCommandAltscreen(act);
 		break;
+	case RC_AUTH:
+		DoCommandAuth(act);
+		break;
 	case RC_BACKTICK:
 		DoCommandBacktick(act);
 		break;

src/screen.c

@@ -90,6 +90,7 @@ static void   SetTtyname(bool fatal, struct stat *st);
 int nversion;			/* numerical version, used for secondary DA */
 
 /* the attacher */
+bool      do_auth = false;
 struct    passwd *ppp;
 char     *attach_tty;
 int       attach_fd = -1;

src/screen.h

@@ -268,6 +268,7 @@ extern bool adaptflag;
 extern bool auto_detach;
 extern bool cjkwidth;
 extern bool default_startup;
+extern bool do_auth;
 extern bool hastruecolor;
 extern bool iflag;
 extern bool logtstamp_on;

src/socket.c

@@ -835,7 +835,10 @@ void ReceiveMsg(void)
 	case MSG_ATTACH:
 		if (CreateTempDisplay(&m, recvfd, win))
 			break;
-		AskPassword(&m);
+		if (do_auth)
+			AskPassword(&m);
+		else
+			FinishAttach(&m);
 		break;
 	case MSG_ERROR:
 		{
@@ -854,7 +857,10 @@ void ReceiveMsg(void)
 	case MSG_POW_DETACH:
 		if (CreateTempDisplay(&m, recvfd, NULL))
 			break;
-		AskPassword(&m);
+		if (do_auth)
+			AskPassword(&m);
+		else
+			FinishAttach(&m);
 		break;
 	case MSG_QUERY:
 		{