Update route if acquired time changes

src/if-linux.c

@@ -752,11 +752,34 @@ if_copyrt(struct dhcpcd_ctx *ctx, struct rt *rt, struct nlmsghdr *nlm)
 			}
 			break;
 		}
-		case RTA_EXPIRES:
+#ifdef HAVE_ROUTE_LIFETIME
+		case RTA_CACHEINFO:
 		{
-			rt->rt_expires = *(uint32_t *)RTA_DATA(rta);
+			struct rta_cacheinfo ci;
+			static long hz;
+
+			if (hz == 0) {
+				hz = sysconf(_SC_CLK_TCK);
+				if (hz == -1)
+					hz = CLOCKS_PER_SEC;
+			}
+
+			memcpy(&ci, RTA_DATA(rta), sizeof(ci));
+			rt->rt_lifetime = (uint32_t)(ci.rta_expires / hz);
 			break;
 		}
+#endif
+#if 0
+		case RTA_EXPIRES:
+			/* Reading the kernel source, this is only
+			 * emitted by IPv4 multicast routes as a UINT64.
+			 * Although we can set it for IPv6 routes as a UINT32,
+			 * the kernel will massage the value to HZ and put it
+			 * into RTA_CACHINFO as read above.
+			 * Gotta love that consistency! */
+			rt->rt_lifetime = (uint32_t)*(uint64_t *)RTA_DATA(rta);
+			break;
+#endif
 		}
 
 		if (sa != NULL) {
@@ -1740,9 +1763,10 @@ if_route(unsigned char cmd, const struct rt *rt)
 	if (!sa_is_loopback(&rt->rt_gateway))
 		add_attr_32(&nlm.hdr, sizeof(nlm), RTA_OIF, rt->rt_ifp->index);
 
-	/* add route lifetime */
-	if (rt->rt_expires != 0)
-		add_attr_32(&nlm.hdr, sizeof(nlm), RTA_EXPIRES, rt->rt_expires);
+#ifdef HAVE_ROUTE_LIFETIME
+	if (rt->rt_lifetime != 0)
+		add_attr_32(&nlm.hdr, sizeof(nlm), RTA_EXPIRES,rt->rt_lifetime);
+#endif
 
 	if (rt->rt_metric != 0)
 		add_attr_32(&nlm.hdr, sizeof(nlm), RTA_PRIORITY,

src/ipv6.c

@@ -2301,9 +2301,10 @@ inet6_raroutes(rb_tree_t *routes, struct dhcpcd_ctx *ctx)
 #ifdef HAVE_ROUTE_PREF
 			rt->rt_pref = ipv6nd_rtpref(rinfo->flags);
 #endif
-			rt->rt_expires = lifetime_left(rinfo->lifetime,
+#ifdef HAVE_ROUTE_LIFETIME
+			rt->rt_lifetime = lifetime_left(rinfo->lifetime,
 			    &rinfo->acquired, &now);
-
+#endif
 			rt_proto_add(routes, rt);
 		}
 
@@ -2317,9 +2318,11 @@ inet6_raroutes(rb_tree_t *routes, struct dhcpcd_ctx *ctx)
 #ifdef HAVE_ROUTE_PREF
 				rt->rt_pref = ipv6nd_rtpref(rap->flags);
 #endif
-				rt->rt_expires =
+#ifdef HAVE_ROUTE_LIFETIME
+				rt->rt_lifetime =
 				    lifetime_left(addr->prefix_vltime,
 				    &addr->acquired, &now);
+#endif
 
 				rt_proto_add(routes, rt);
 			}
@@ -2352,8 +2355,10 @@ inet6_raroutes(rb_tree_t *routes, struct dhcpcd_ctx *ctx)
 #ifdef HAVE_ROUTE_PREF
 		rt->rt_pref = ipv6nd_rtpref(rap->flags);
 #endif
-		rt->rt_expires = lifetime_left(rap->lifetime,
+#ifdef HAVE_ROUTE_LIFETIME
+		rt->rt_lifetime = lifetime_left(rap->lifetime,
 		    &rap->acquired, &now);
+#endif
 
 		rt_proto_add(routes, rt);
 	}

src/route.c

@@ -502,6 +502,32 @@ rt_recvrt(int cmd, const struct rt *rt, pid_t pid)
 #endif
 }
 
+/* Compare miscellaneous route details */
+static bool
+rt_cmp_misc(struct rt *nrt, struct rt *ort)
+{
+	/* MTU changed */
+	if (ort->rt_mtu != nrt->rt_mtu)
+		return false;
+
+#ifdef HAVE_ROUTE_LIFETIME
+	uint32_t deviation;
+
+	/* There might be a minor difference between kernel route
+	 * lifetime and our lifetime due to processing times.
+	 * We allow a small deviation to avoid needless route changes.
+	 * dhcpcd will expire the route regardless of route lifetime support. */
+	if (nrt->rt_lifetime > ort->rt_lifetime)
+		deviation = nrt->rt_lifetime - ort->rt_lifetime;
+	else
+		deviation = ort->rt_lifetime - nrt->rt_lifetime;
+	if (deviation > RTLIFETIME_DEV_MAX)
+		return false;
+#endif
+
+	return true;
+}
+
 static bool
 rt_add(rb_tree_t *kroutes, struct rt *nrt, struct rt *ort)
 {
@@ -540,7 +566,7 @@ rt_add(rb_tree_t *kroutes, struct rt *nrt, struct rt *ort)
 #endif
 		    sa_cmp(&ort->rt_gateway, &nrt->rt_gateway) == 0)))
 		{
-			if (ort->rt_mtu == nrt->rt_mtu)
+			if (rt_cmp_misc(nrt, ort))
 				return true;
 			change = true;
 			kroute = true;
@@ -555,7 +581,7 @@ rt_add(rb_tree_t *kroutes, struct rt *nrt, struct rt *ort)
 	    rt_cmp_netmask(ort, nrt) == 0 &&
 	    sa_cmp(&ort->rt_gateway, &nrt->rt_gateway) == 0)
 	{
-		if (ort->rt_mtu == nrt->rt_mtu)
+		if (rt_cmp_misc(nrt, ort))
 			return true;
 		change = true;
 	}
@@ -678,7 +704,7 @@ rt_doroute(rb_tree_t *kroutes, struct rt *rt)
 		    !rt_cmp(rt, or) ||
 		    (rt->rt_ifa.sa_family != AF_UNSPEC &&
 		    sa_cmp(&or->rt_ifa, &rt->rt_ifa) != 0) ||
-		    or->rt_mtu != rt->rt_mtu)
+		    !rt_cmp_misc(rt, or))
 		{
 			if (!rt_add(kroutes, rt, or))
 				return false;

src/route.h

@@ -59,6 +59,11 @@
 #  define HAVE_ROUTE_METRIC 1
 # endif
 #endif
+#ifndef HAVE_ROUTE_LIFETIME
+# if defined(__linux__)
+#  define HAVE_ROUTE_LIFETIME 1 /* For IPv6 routes only */
+# endif
+#endif
 
 #ifdef __linux__
 # include <linux/version.h> /* RTA_PREF is only an enum.... */
@@ -120,7 +125,10 @@ struct rt {
 #define	RTDF_GATELINK		0x40		/* Gateway is on link */
 	size_t			rt_order;
 	rb_node_t		rt_tree;
-	uint32_t		rt_expires;	/* current lifetime of route */
+#ifdef HAVE_ROUTE_LIFETIME
+	uint32_t		rt_lifetime;	/* current lifetime of route */
+#define	RTLIFETIME_DEV_MAX	2 		/* max deviation for cmp */
+#endif
 };
 
 extern const rb_tree_ops_t rt_compare_list_ops;