[dhcp] Reset start time when deferring discovery

If we detect (via STP) that a switch port is in a non-forwarding state, then the link is marked as being temporarily blocked and DHCP discovery will be deferred until the link becomes unblocked. The timer used to decide when to give up waiting for ProxyDHCPOFFERs is currently based on the time that DHCP discovery was started, and makes no allowances for any time spent waiting for the link to become unblocked. Consequently, if STP is used then the timeout for ProxyDHCPOFFERs becomes essentially zero. Fix by resetting the recorded start time whenever DHCP discovery is deferred due to a blocked link. Debugged-by: Sebastian Roth <sebastian.roth@zoho.com> Signed-off-by: Michael Brown <mcb30@ipxe.org>
ipxe · Oct 30, 2015 · 7cc7e0e · 7cc7e0e
1 parent 6847232
commit 7cc7e0e
Showing 1 changed file with 1 addition and 0 deletions.
diff --git a/src/net/udp/dhcp.c b/src/net/udp/dhcp.c
@@ -446,6 +446,7 @@ static void dhcp_discovery_expired ( struct dhcp_session *dhcp ) {
 	/* If link is blocked, defer DHCP discovery (and reset timeout) */
 	if ( netdev_link_blocked ( dhcp->netdev ) ) {
 		DBGC ( dhcp, "DHCP %p deferring discovery\n", dhcp );
+		dhcp->start = currticks();
 		start_timer_fixed ( &dhcp->timer,
 				    ( DHCP_DISC_START_TIMEOUT_SEC *
 				      TICKS_PER_SEC ) );