ControlPersist.

[David Woodhouse]

This is a better approach to persistent control masters than my previous
attempt. Instead of forking before we make the connection, do so only
when the original session has closed -- much like the code for '~&'
backgrounding already does. 

My earlier patch for 'ControlPath none' still applies and is required, btw.

--- openssh/clientloop.c~	2005-06-17 03:59:35.000000000 +0100
+++ openssh/clientloop.c	2005-06-23 11:05:11.000000000 +0100
@@ -1271,8 +1271,28 @@ static void
 client_channel_closed(int id, void *arg)
 {
 	channel_cancel_cleanup(id);
-	session_closed = 1;
 	leave_raw_mode();
+	if (options.control_persist && options.control_path != NULL && control_fd != -1) {
+		int pid = fork();
+
+		if (pid < 0) {
+			error("fork: %.100s", strerror(errno));
+			/* Just exit */
+			session_closed = 1;
+			return;
+		}
+		if (pid != 0) {
+			/* We are the parent. Exit, leaving the child to continue serving */
+			exit(exit_status);
+		}
+		session_ident = -1;
+		/* We _must_ lose our controlling tty, else subsequent control_client
+		   invocations from the same tty will cause us to get -EIO when reading
+		   from the tty */
+		setsid();
+		return;
+	}
+	session_closed = 1;
 }
 
 /*
--- openssh/readconf.c~	2005-06-16 04:19:42.000000000 +0100
+++ openssh/readconf.c	2005-06-23 11:05:11.000000000 +0100
@@ -106,7 +106,7 @@ typedef enum {
 	oEnableSSHKeysign, oRekeyLimit, oVerifyHostKeyDNS, oConnectTimeout,
 	oAddressFamily, oGssAuthentication, oGssDelegateCreds,
 	oServerAliveInterval, oServerAliveCountMax, oIdentitiesOnly,
-	oSendEnv, oControlPath, oControlMaster, oHashKnownHosts,
+	oSendEnv, oControlPath, oControlMaster, oControlPersist, oHashKnownHosts,
 	oDeprecated, oUnsupported
 } OpCodes;
 
@@ -197,6 +197,7 @@ static struct {
 	{ "sendenv", oSendEnv },
 	{ "controlpath", oControlPath },
 	{ "controlmaster", oControlMaster },
+	{ "controlpersist", oControlPersist },
 	{ "hashknownhosts", oHashKnownHosts },
 	{ NULL, oBadOption }
 };
@@ -818,6 +819,10 @@ parse_int:
 			*intptr = value;
 		break;
 
+	case oControlPersist:
+		intptr = &options->control_persist;
+		goto parse_flag;
+
 	case oHashKnownHosts:
 		intptr = &options->hash_known_hosts;
 		goto parse_flag;
--- openssh/readconf.h~	2005-06-16 04:19:42.000000000 +0100
+++ openssh/readconf.h	2005-06-23 11:02:01.000000000 +0100
@@ -112,6 +112,7 @@ typedef struct {
 
 	char	*control_path;
 	int	control_master;
+	int	control_persist;
 
 	int	hash_known_hosts;
 }       Options;


-- 
dwmw2