Stop a mesh STA from flooding with peer frames.

This problem happens when using ACL policy to filter mesh STA
but two nodes have different policy. Then one of them will try to
peer all the time. This can also help if for any reason one of the
peering mesh STA have problems sending/receiving peer frames.

* Modified struct ieee80211_node to include two new fields:
    + struct callout ni_mlhtimer /* link mesh backoff timer */
    + uint8_t ni_mlhcnt /* link mesh holding counter */
* Added two new sysctl (check sysctl -d for more info):
    + net.wlan.mesh.backofftimeout=5000
    + net.wlan.mesh.maxholding=2;
* When receiving a beacon and we are in IEEE80211_NODE_MESH_IDLE
  check if ni_mlhcnt >= ieee80211_mesh_maxholding, if so do not do anything;
* In mesh_peer_timeout_cb when transitioning from IEEE80211_NODE_MESH_HOLDING
  to IEEE80211_NODE_MESH_IDLE increment ni_mlhcnt, and eventually start
  ieee80211_mesh_backofftimeout;

Approved by:	adrian (mentor)

1 files changed, 31 insertions, 1 deletions

diff --git a/sys/net80211/ieee80211_mesh.c b/sys/net80211/ieee80211_mesh.c
index 6ab76d9..d2f63e5 100644
--- a/sys/net80211/ieee80211_mesh.c
+++ b/sys/net80211/ieee80211_mesh.c
@@ -111,10 +111,20 @@ static int ieee80211_mesh_confirmtimeout = -1;
 SYSCTL_PROC(_net_wlan_mesh, OID_AUTO, confirmtimeout, CTLTYPE_INT | CTLFLAG_RW,
     &ieee80211_mesh_confirmtimeout, 0, ieee80211_sysctl_msecs_ticks, "I",
     "Confirm state timeout (msec)");
+static int ieee80211_mesh_backofftimeout = -1;
+SYSCTL_PROC(_net_wlan_mesh, OID_AUTO, backofftimeout, CTLTYPE_INT | CTLFLAG_RW,
+    &ieee80211_mesh_backofftimeout, 0, ieee80211_sysctl_msecs_ticks, "I",
+    "Backoff timeout (msec). This is to throutles peering forever when "
+    "not receving answer or is rejected by a neighbor");
 static int ieee80211_mesh_maxretries = 2;
 SYSCTL_INT(_net_wlan_mesh, OID_AUTO, maxretries, CTLTYPE_INT | CTLFLAG_RW,
     &ieee80211_mesh_maxretries, 0,
     "Maximum retries during peer link establishment");
+static int ieee80211_mesh_maxholding = 2;
+SYSCTL_INT(_net_wlan_mesh, OID_AUTO, maxholding, CTLTYPE_INT | CTLFLAG_RW,
+    &ieee80211_mesh_maxholding, 0,
+    "Maximum times we are allowed to transition to HOLDING state before "
+    "backinoff during peer link establishment");
 
 static const uint8_t broadcastaddr[IEEE80211_ADDR_LEN] =
 	{ 0xff, 0xff, 0xff, 0xff, 0xff, 0xff };
@@ -500,6 +510,7 @@ ieee80211_mesh_init(void)
 	ieee80211_mesh_retrytimeout = msecs_to_ticks(40);
 	ieee80211_mesh_holdingtimeout = msecs_to_ticks(40);
 	ieee80211_mesh_confirmtimeout = msecs_to_ticks(40);
+	ieee80211_mesh_backofftimeout = msecs_to_ticks(5000);
 
 	/*
 	 * Register action frame handlers.
@@ -1696,7 +1707,6 @@ mesh_recv_mgmt(struct ieee80211_node *ni, struct mbuf *m0, int subtype,
 		}
 		/*
 		 * Automatically peer with discovered nodes if possible.
-		 * XXX backoff on repeated failure
 		 */
 		if (ni != vap->iv_bss &&
 		    (ms->ms_flags & IEEE80211_MESHFLAGS_AP)) {
@@ -1705,6 +1715,10 @@ mesh_recv_mgmt(struct ieee80211_node *ni, struct mbuf *m0, int subtype,
 			{
 				uint16_t args[1];
 
+				/* Wait for backoff callout to reset counter */
+				if (ni->ni_mlhcnt >= ieee80211_mesh_maxholding)
+					return;
+
 				ni->ni_mlpid = mesh_generateid(vap);
 				if (ni->ni_mlpid == 0)
 					return;
@@ -2578,6 +2592,15 @@ mesh_peer_timeout_stop(struct ieee80211_node *ni)
 	callout_drain(&ni->ni_mltimer);
 }
 
+static void
+mesh_peer_backoff_cb(void *arg)
+{
+	struct ieee80211_node *ni = (struct ieee80211_node *)arg;
+
+	/* After backoff timeout, try to peer automatically again. */
+	ni->ni_mlhcnt = 0;
+}
+
 /*
  * Mesh Peer Link Management FSM timeout handling.
  */
@@ -2625,6 +2648,11 @@ mesh_peer_timeout_cb(void *arg)
 		mesh_peer_timeout_setup(ni);
 		break;
 	case IEEE80211_NODE_MESH_HOLDING:
+		ni->ni_mlhcnt++;
+		if (ni->ni_mlhcnt >= ieee80211_mesh_maxholding)
+			callout_reset(&ni->ni_mlhtimer,
+			    ieee80211_mesh_backofftimeout,
+			    mesh_peer_backoff_cb, ni);
 		mesh_linkchange(ni, IEEE80211_NODE_MESH_IDLE);
 		break;
 	}
@@ -2889,6 +2917,7 @@ ieee80211_mesh_node_init(struct ieee80211vap *vap, struct ieee80211_node *ni)
 {
 	ni->ni_flags |= IEEE80211_NODE_QOS;
 	callout_init(&ni->ni_mltimer, CALLOUT_MPSAFE);
+	callout_init(&ni->ni_mlhtimer, CALLOUT_MPSAFE);
 }
 
 /*
@@ -2901,6 +2930,7 @@ ieee80211_mesh_node_cleanup(struct ieee80211_node *ni)
 	struct ieee80211_mesh_state *ms = vap->iv_mesh;
 
 	callout_drain(&ni->ni_mltimer);
+	callout_drain(&ni->ni_mlhtimer);
 	/* NB: short-circuit callbacks after mesh_vdetach */
 	if (vap->iv_mesh != NULL)
 		ms->ms_ppath->mpp_peerdown(ni);