From: Roy Marples <roy@marples.name>
Date: Sat, 30 Apr 2016 07:30:40 +0000 (+0000)
Subject: Move last last extending into it's own option so we can use the last lease
X-Git-Tag: v6.11.0~61
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=b1ad0d3926cc5ddcedfdeaf4ede5b86e5b983daf;p=thirdparty%2Fdhcpcd.git

Move last last extending into it's own option so we can use the last lease
in a RFC compliant or incompliant way by choice.
---

diff --git a/dhcp.c b/dhcp.c
index 15fba788..03f822d1 100644
--- a/dhcp.c
+++ b/dhcp.c
@@ -1850,7 +1850,7 @@ 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 (ifp->options->options & DHCPCD_LASTLEASE_EXTEND) {
 		if (dhcp_leaseextend(ifp) == 0)
 			return;
 		logger(ifp->ctx, LOG_ERR, "%s: dhcp_leaseextend: %m",
@@ -2185,7 +2185,9 @@ dhcp_lastlease(void *arg)
 	if (ifp->ctx->options & DHCPCD_FORKED)
 		return;
 	state->interval = 0;
-	if (dhcp_leaseextend(ifp) == -1) {
+	if (ifp->options->options & DHCPCD_LASTLEASE_EXTEND &&
+	    dhcp_leaseextend(ifp) == -1)
+	{
 		logger(ifp->ctx, LOG_ERR, "%s: dhcp_leaseextend: %m",
 		    ifp->name);
 		dhcp_expire(ifp);
@@ -3409,7 +3411,7 @@ dhcp_start1(void *arg)
 				free(state->offer);
 				state->offer = NULL;
 			}
-		} else if (!(ifo->options & DHCPCD_LASTLEASE) &&
+		} else if (!(ifo->options & DHCPCD_LASTLEASE_EXTEND) &&
 		    state->lease.leasetime != ~0U &&
 		    stat(state->leasefile, &st) == 0)
 		{
@@ -3470,6 +3472,11 @@ dhcp_start(struct interface *ifp)
 	if (!(ifp->options->options & DHCPCD_IPV4))
 		return;
 
+	/* If we violate RFC2131 section 3.7 then require ARP
+	 * to detect if any other client wants our address. */
+	if (ifp->options->options & DHCPCD_LASTLEASE_EXTEND)
+		ifp->options->options |= DHCPCD_ARP;
+
 	/* No point in delaying a static configuration */
 	if (ifp->options->options & DHCPCD_STATIC ||
 	    !(ifp->options->options & DHCPCD_INITIAL_DELAY))
diff --git a/dhcpcd.8.in b/dhcpcd.8.in
index a72502a5..6772968e 100644
--- a/dhcpcd.8.in
+++ b/dhcpcd.8.in
@@ -22,7 +22,7 @@
 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 .\" SUCH DAMAGE.
 .\"
-.Dd April 27, 2016
+.Dd April 30, 2016
 .Dt DHCPCD 8
 .Os
 .Sh NAME
@@ -268,9 +268,12 @@ If
 .Nm
 cannot obtain a lease, then try to use the last lease acquired for the
 interface.
-If the
-.Fl p, Fl Fl persistent
-option is not given then the lease is used if it hasn't expired.
+.It Fl Fl lastleaseextend
+Same as the above, but he lease will be retained even if it expires.
+.Nm
+will give it up if any other host tries to claim it for their own via ARP.
+This is does violate RFC2131 section 3.7 which states the lease should be
+dropped once it has expired.
 .It Fl e , Fl Fl env Ar value
 Push
 .Ar value
diff --git a/if-options.c b/if-options.c
index 75d381d8..6b2052bb 100644
--- a/if-options.c
+++ b/if-options.c
@@ -100,6 +100,7 @@
 #define O_DEFINEND		O_BASE + 43
 #define O_NODELAY		O_BASE + 44
 #define O_INFORM6		O_BASE + 45
+#define O_LASTLEASE_EXTEND	O_BASE + 46
 
 const struct option cf_options[] = {
 	{"background",      no_argument,       NULL, 'b'},
@@ -198,6 +199,7 @@ const struct option cf_options[] = {
 	{"bootp",           no_argument,       NULL, O_BOOTP},
 	{"nodelay",         no_argument,       NULL, O_NODELAY},
 	{"noup",            no_argument,       NULL, O_NOUP},
+	{"lastleaseextend", no_argument,       NULL, O_LASTLEASE_EXTEND},
 	{NULL,              0,                 NULL, '\0'}
 };
 
@@ -2086,6 +2088,9 @@ err_sla:
 	case O_NODELAY:
 		ifo->options &= ~DHCPCD_INITIAL_DELAY;
 		break;
+	case O_LASTLEASE_EXTEND:
+		ifo->options |= DHCPCD_LASTLEASE | DHCPCD_LASTLEASE_EXTEND;
+		break;
 	default:
 		return 0;
 	}
diff --git a/if-options.h b/if-options.h
index 9d825569..a0be326a 100644
--- a/if-options.h
+++ b/if-options.h
@@ -110,7 +110,7 @@
 #define DHCPCD_RTM_PPID			(1ULL << 53)
 #define DHCPCD_IPV6RA_AUTOCONF		(1ULL << 54)
 #define DHCPCD_ROUTER_HOST_ROUTE_WARNED	(1ULL << 55)
-// unassigned	(1ULL << 56)
+#define DHCPCD_LASTLEASE_EXTEND		(1ULL << 56)
 #define DHCPCD_BOOTP			(1ULL << 57)
 #define DHCPCD_INITIAL_DELAY		(1ULL << 58)
 #define DHCPCD_PRINT_PIDFILE		(1ULL << 59)