[eapol] Limit number of EAPoL-Start packets transmitted per attempt

Signed-off-by: Michael Brown <mcb30@ipxe.org>

2 files changed, 13 insertions, 0 deletions

diff --git a/src/include/ipxe/eapol.h b/src/include/ipxe/eapol.h
index d4ea392..dcf3929 100644
--- a/src/include/ipxe/eapol.h
+++ b/src/include/ipxe/eapol.h
@@ -42,11 +42,16 @@ struct eapol_supplicant {
 	struct eap_supplicant eap;
 	/** EAPoL-Start retransmission timer */
 	struct retry_timer timer;
+	/** EAPoL-Start transmission count */
+	unsigned int count;
 };
 
 /** Delay between EAPoL-Start packets */
 #define EAPOL_START_INTERVAL ( 2 * TICKS_PER_SEC )
 
+/** Maximum number of EAPoL-Start packets to transmit */
+#define EAPOL_START_COUNT 3
+
 /** An EAPoL handler */
 struct eapol_handler {
 	/** Type */
diff --git a/src/net/eapol.c b/src/net/eapol.c
index ce7be55..8b09ca2 100644
--- a/src/net/eapol.c
+++ b/src/net/eapol.c
@@ -167,6 +167,7 @@ static int eapol_eap_rx ( struct eapol_supplicant *supplicant,
 		/* Delay EAPoL-Start until after next expected packet */
 		DBGC ( netdev, "EAPOL %s deferring Start\n", netdev->name );
 		start_timer_fixed ( &supplicant->timer, EAP_WAIT_TIMEOUT );
+		supplicant->count = 0;
 	}
 
  drop:
@@ -250,6 +251,12 @@ static void eapol_expired ( struct retry_timer *timer, int fail __unused ) {
 		container_of ( timer, struct eapol_supplicant, timer );
 	struct net_device *netdev = supplicant->eap.netdev;
 
+	/* Stop transmitting after maximum number of attempts */
+	if ( supplicant->count++ >= EAPOL_START_COUNT ) {
+		DBGC ( netdev, "EAPOL %s giving up\n", netdev->name );
+		return;
+	}
+
 	/* Schedule next transmission */
 	start_timer_fixed ( timer, EAPOL_START_INTERVAL );
 
@@ -317,6 +324,7 @@ static void eapol_notify ( struct net_device *netdev, void *priv ) {
 
 	/* Otherwise, start sending EAPoL-Start */
 	start_timer_nodelay ( &supplicant->timer );
+	supplicant->count = 0;
 	DBGC ( netdev, "EAPOL %s starting up\n", netdev->name );
 }