From 24dbc4b172166fe69d027ac0c438c5dae8dce694 Mon Sep 17 00:00:00 2001
From: Roy Marples <roy@marples.name>
Date: Fri, 29 Apr 2016 22:48:19 +0000
Subject: [PATCH] When the leaselease option is given, retain the lease when
 the DHCP lease expires, which mirrors how dhcpcd works when it starts up.
 However, if any ARP probe is for the address, drop the lease right away and
 continue discovery.

---
 dhcp.c | 66 +++++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 59 insertions(+), 7 deletions(-)

diff --git a/dhcp.c b/dhcp.c
index d2a9678a..e4baa03d 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -118,7 +118,8 @@ struct udp_dhcp_packet
 
 static const size_t udp_dhcp_len = sizeof(struct udp_dhcp_packet);
 
-static int dhcp_open(struct interface *ifp);
+static int dhcp_open(struct interface *);
+static void dhcp_arp_conflicted(struct arp_state *, const struct arp_msg *);
 
 void
 dhcp_printoptions(const struct dhcpcd_ctx *ctx,
@@ -1808,18 +1809,48 @@ dhcp_request(void *arg)
 	send_request(ifp);
 }
 
+static int
+dhcp_leaseextend(struct interface *ifp)
+{
+	struct arp_state *astate;
+
+	if ((astate = arp_new(ifp, NULL)) == NULL)
+		return -1;
+
+	if (arp_open(ifp) == -1)
+		return -1;
+
+	astate->conflicted_cb = dhcp_arp_conflicted;
+	logger(ifp->ctx, LOG_WARNING,
+	    "%s: keeping lease until DaD failure or DHCP", ifp->name);
+	return 0;
+}
+
 static void
-dhcp_expire(void *arg)
+dhcp_expire1(struct interface *ifp)
 {
-	struct interface *ifp = arg;
 	struct dhcp_state *state = D_STATE(ifp);
 
-	logger(ifp->ctx, LOG_ERR, "%s: DHCP lease expired", ifp->name);
 	eloop_timeout_delete(ifp->ctx->eloop, NULL, ifp);
 	dhcp_drop(ifp, "EXPIRE");
 	unlink(state->leasefile);
 	state->interval = 0;
 	dhcp_discover(ifp);
+
+}
+static void
+dhcp_expire(void *arg)
+{
+	struct interface *ifp = arg;
+
+	logger(ifp->ctx, LOG_ERR, "%s: DHCP lease expired", ifp->name);
+	if (ifp->options->options & DHCPCD_LASTLEASE) {
+		if (dhcp_leaseextend(ifp) == 0)
+			return;
+		logger(ifp->ctx, LOG_ERR, "%s: dhcp_leaseextend: %m",
+		    ifp->name);
+	}
+	dhcp_expire1(ifp);
 }
 
 static void
@@ -2003,6 +2034,21 @@ dhcp_arp_conflicted(struct arp_state *astate, const struct arp_msg *amsg)
 		eloop_timeout_add_sec(ifp->ctx->eloop,
 		    DHCP_RAND_MAX, dhcp_discover, ifp);
 	}
+
+	/* Bound address */
+	if (amsg &&
+	    (amsg->sip.s_addr == state->addr.s_addr ||
+	    (amsg->sip.s_addr == 0 && amsg->tip.s_addr == state->addr.s_addr)))
+	{
+		astate->failed = state->addr;
+		arp_report_conflicted(astate, amsg);
+		if (state->state == DHS_BOUND) {
+			/* For now, just report the duplicated address */
+		} else {
+			arp_free(astate);
+			dhcp_expire1(ifp);
+		}
+	}
 }
 
 void
@@ -2123,7 +2169,7 @@ dhcp_bind(struct interface *ifp)
 }
 
 static void
-dhcp_timeout(void *arg)
+dhcp_lastlease(void *arg)
 {
 	struct interface *ifp = arg;
 	struct dhcp_state *state = D_STATE(ifp);
@@ -2133,6 +2179,11 @@ dhcp_timeout(void *arg)
 	if (ifp->ctx->options & DHCPCD_FORKED)
 		return;
 	state->interval = 0;
+	if (dhcp_leaseextend(ifp) == -1) {
+		logger(ifp->ctx, LOG_ERR, "%s: dhcp_leaseextend: %m",
+		    ifp->name);
+		dhcp_expire(ifp);
+	}
 	dhcp_discover(ifp);
 }
 
@@ -2368,7 +2419,7 @@ dhcp_reboot(struct interface *ifp)
 
 	if (ifo->options & DHCPCD_LASTLEASE && state->lease.frominfo)
 		eloop_timeout_add_sec(ifp->ctx->eloop,
-		    ifo->reboot, dhcp_timeout, ifp);
+		    ifo->reboot, dhcp_lastlease, ifp);
 	else if (!(ifo->options & DHCPCD_INFORM))
 		eloop_timeout_add_sec(ifp->ctx->eloop,
 		    ifo->reboot, dhcp_expire, ifp);
@@ -3352,7 +3403,8 @@ dhcp_start1(void *arg)
 				free(state->offer);
 				state->offer = NULL;
 			}
-		} else if (state->lease.leasetime != ~0U &&
+		} else if (!(ifo->options & DHCPCD_LASTLEASE) &&
+		    state->lease.leasetime != ~0U &&
 		    stat(state->leasefile, &st) == 0)
 		{
 			time_t now;
-- 
2.47.3