Add an optional "persistent" flag to ng_hub and ng_bridge, which if set,

disables automatic node shutdown when the last hook gets disconnected.

Reviewed by:	julian

share/man/man4/ng_bridge.4

@@ -34,7 +34,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd August 31, 2000
+.Dd May 5, 2010
 .Dt NG_BRIDGE 4
 .Os
 .Sh NAME
@@ -181,11 +181,17 @@ but also atomically clears the statistics as well.
 .It Dv NGM_BRIDGE_GET_TABLE
 Returns the current host mapping table used to direct packets, in a
 .Dv "struct ng_bridge_host_ary" .
+.It Dv NGM_BRIDGE_SET_PERSISTENT
+This command sets the persistent flag on the node, and takes no arguments.
 .El
 .Sh SHUTDOWN
 This node shuts down upon receipt of a
 .Dv NGM_SHUTDOWN
-control message, or when all hooks have been disconnected.
+control message, or when all hooks have been disconnected.  Setting the
+persistent flag via a
+.Dv NGM_BRIDGE_SET_PERSISTENT
+control message disables automatic node shutdown when the last hook gets
+disconnected.
 .Sh FILES
 .Bl -tag -width XXXXXXXX -compact
 .It Pa /usr/share/examples/netgraph/ether.bridge

share/man/man4/ng_hub.4

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd April 17, 2004
+.Dd May 5, 2010
 .Dt NG_HUB 4
 .Os
 .Sh NAME
@@ -45,11 +45,20 @@ A
 node accepts any request to connect, regardless of the hook name,
 as long as the name is unique.
 .Sh CONTROL MESSAGES
-This node type supports only the generic control messages.
+This node type supports the generic control messages, plus the
+following:
+.Bl -tag -width foo
+.It Dv NGM_HUB_SET_PERSISTENT
+This command sets the persistent flag on the node, and takes no arguments.
+.El
 .Sh SHUTDOWN
 This node shuts down upon receipt of a
 .Dv NGM_SHUTDOWN
-control message, or when all hooks have been disconnected.
+control message, or when all hooks have been disconnected.  Setting the
+persistent flag via a
+.Dv NGM_HUB_SET_PERSISTENT
+control message disables automatic node shutdown when the last hook gets
+disconnected.
 .Sh SEE ALSO
 .Xr netgraph 4 ,
 .Xr ng_bridge 4 ,

sys/netgraph/ng_bridge.c

@@ -84,7 +84,7 @@
 #include <netgraph/ng_bridge.h>
 
 #ifdef NG_SEPARATE_MALLOC
-MALLOC_DEFINE(M_NETGRAPH_BRIDGE, "netgraph_bridge", "netgraph bridge node ");
+MALLOC_DEFINE(M_NETGRAPH_BRIDGE, "netgraph_bridge", "netgraph bridge node");
 #else
 #define M_NETGRAPH_BRIDGE M_NETGRAPH
 #endif
@@ -106,6 +106,7 @@ struct ng_bridge_private {
 	u_int			numBuckets;	/* num buckets in table */
 	u_int			hashMask;	/* numBuckets - 1 */
 	int			numLinks;	/* num connected links */
+	int			persistent;	/* can exist w/o hooks */
 	struct callout		timer;		/* one second periodic timer */
 };
 typedef struct ng_bridge_private *priv_p;
@@ -271,6 +272,13 @@ static const struct ng_cmdlist ng_bridge_cmdlist[] = {
 	  NULL,
 	  &ng_bridge_host_ary_type
 	},
+	{
+	  NGM_BRIDGE_COOKIE,
+	  NGM_BRIDGE_SET_PERSISTENT,
+	  "setpersistent",
+	  NULL,
+	  NULL
+	},
 	{ 0 }
 };
 
@@ -495,6 +503,11 @@ ng_bridge_rcvmsg(node_p node, item_p item, hook_p lasthook)
 			}
 			break;
 		    }
+		case NGM_BRIDGE_SET_PERSISTENT:
+		    {
+			priv->persistent = 1;
+			break;
+		    }
 		default:
 			error = EINVAL;
 			break;
@@ -800,7 +813,8 @@ ng_bridge_disconnect(hook_p hook)
 
 	/* If no more hooks, go away */
 	if ((NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0)
-	&& (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))) {
+	    && (NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))
+	    && !priv->persistent) {
 		ng_rmnode_self(NG_HOOK_NODE(hook));
 	}
 	return (0);

sys/netgraph/ng_bridge.h

@@ -149,6 +149,7 @@ enum {
 	NGM_BRIDGE_CLR_STATS,		/* clear link stats */
 	NGM_BRIDGE_GETCLR_STATS,	/* atomically get & clear link stats */
 	NGM_BRIDGE_GET_TABLE,		/* get link table */
+	NGM_BRIDGE_SET_PERSISTENT,	/* set persistent mode */
 };
 
 #endif /* _NETGRAPH_NG_BRIDGE_H_ */

sys/netgraph/ng_hub.c

@@ -36,16 +36,46 @@
 #include <netgraph/ng_hub.h>
 #include <netgraph/netgraph.h>
 
+#ifdef NG_SEPARATE_MALLOC
+MALLOC_DEFINE(M_NETGRAPH_HUB, "netgraph_hub", "netgraph hub node");
+#else
+#define M_NETGRAPH_HUB M_NETGRAPH
+#endif
+
+/* Per-node private data */
+struct ng_hub_private {
+	int		persistent;	/* can exist w/o hooks */
+};
+typedef struct ng_hub_private *priv_p;
+
+/* Netgraph node methods */
 static ng_constructor_t	ng_hub_constructor;
+static ng_rcvmsg_t	ng_hub_rcvmsg;
+static ng_shutdown_t	ng_hub_shutdown;
 static ng_rcvdata_t	ng_hub_rcvdata;
 static ng_disconnect_t	ng_hub_disconnect;
 
+/* List of commands and how to convert arguments to/from ASCII */
+static const struct ng_cmdlist ng_hub_cmdlist[] = {
+	{
+		NGM_HUB_COOKIE,
+		NGM_HUB_SET_PERSISTENT,
+		"setpersistent",
+		NULL,
+		NULL
+	},
+	{ 0 }
+};
+
 static struct ng_type ng_hub_typestruct = {
 	.version =	NG_ABI_VERSION,
 	.name =		NG_HUB_NODE_TYPE,
 	.constructor =	ng_hub_constructor,
+	.rcvmsg =	ng_hub_rcvmsg,
+	.shutdown =	ng_hub_shutdown,
 	.rcvdata =	ng_hub_rcvdata,
 	.disconnect =	ng_hub_disconnect,
+	.cmdlist =	ng_hub_cmdlist,
 };
 NETGRAPH_INIT(hub, &ng_hub_typestruct);
 
@@ -53,10 +83,39 @@ NETGRAPH_INIT(hub, &ng_hub_typestruct);
 static int
 ng_hub_constructor(node_p node)
 {
+	priv_p priv;
 
+	/* Allocate and initialize private info */
+	priv = malloc(sizeof(*priv), M_NETGRAPH_HUB, M_NOWAIT | M_ZERO);
+	if (priv == NULL)
+		return (ENOMEM);
+
+	NG_NODE_SET_PRIVATE(node, priv);
 	return (0);
 }
 
+/*
+ * Receive a control message
+ */
+static int
+ng_hub_rcvmsg(node_p node, item_p item, hook_p lasthook)
+{
+	const priv_p priv = NG_NODE_PRIVATE(node);
+	int error = 0;
+	struct ng_mesg *msg;
+
+	NGI_GET_MSG(item, msg);
+	if (msg->header.typecookie == NGM_HUB_COOKIE &&
+	    msg->header.cmd == NGM_HUB_SET_PERSISTENT) {
+		priv->persistent = 1;
+	} else {
+		error = EINVAL;
+	}
+
+	NG_FREE_MSG(msg);
+	return (error);
+}
+
 static int
 ng_hub_rcvdata(hook_p hook, item_p item)
 {
@@ -89,12 +148,25 @@ ng_hub_rcvdata(hook_p hook, item_p item)
 	return (error);
 }
 
+/*
+ * Shutdown node
+ */
+static int
+ng_hub_shutdown(node_p node)
+{
+	const priv_p priv = NG_NODE_PRIVATE(node);
+
+	free(priv, M_NETGRAPH_HUB);
+	return (0);
+}
+
 static int
 ng_hub_disconnect(hook_p hook)
 {
+	const priv_p priv = NG_NODE_PRIVATE(NG_HOOK_NODE(hook));
 
 	if (NG_NODE_NUMHOOKS(NG_HOOK_NODE(hook)) == 0 &&
-	    NG_NODE_IS_VALID(NG_HOOK_NODE(hook)))
+	    NG_NODE_IS_VALID(NG_HOOK_NODE(hook)) && !priv->persistent)
 		ng_rmnode_self(NG_HOOK_NODE(hook));
 	return (0);
 }

sys/netgraph/ng_hub.h

@@ -33,4 +33,9 @@
 #define	NG_HUB_NODE_TYPE	"hub"
 #define	NGM_HUB_COOKIE		1082189597
 
+/* Netgraph control messages */
+enum {
+	NGM_HUB_SET_PERSISTENT = 1,	/* set persistent mode */
+};
+
 #endif /* _NETGRAPH_NG_HUB_H_ */