Add route lifetime from Router Advertisement (#429)

Currently this is only for Linux and is fairly cosmetic as dhcpcd will
clean up expired routes itself as other OS's don't support route lifetimes.

Author: ColinMcInnes

src/common.c

@@ -38,6 +38,7 @@
 
 #include "common.h"
 #include "dhcpcd.h"
+#include "eloop.h"
 #include "if-options.h"
 
 const char *
@@ -214,3 +215,18 @@ is_root_local(void)
 	return -1;
 #endif
 }
+
+uint32_t
+lifetime_left(uint32_t lifetime, const struct timespec *acquired, const struct timespec *now)
+{
+	uint32_t elapsed;
+
+	if (lifetime == INFINITE_LIFETIME)
+		return lifetime;
+
+	elapsed = (uint32_t)eloop_timespec_diff(now, acquired, NULL);
+	if (elapsed > lifetime)
+		return 0;
+
+	return lifetime - elapsed;
+}

src/common.h

@@ -141,11 +141,14 @@
 # endif
 #endif
 
+#define INFINITE_LIFETIME (~0U)
+
 const char *hwaddr_ntoa(const void *, size_t, char *, size_t);
 size_t hwaddr_aton(uint8_t *, const char *);
 ssize_t readfile(const char *, void *, size_t);
 ssize_t writefile(const char *, mode_t, const void *, size_t);
 int filemtime(const char *, time_t *);
 char *get_line(char ** __restrict, ssize_t * __restrict);
 int is_root_local(void);
+uint32_t lifetime_left(uint32_t, const struct timespec *, const struct timespec *);
 #endif

src/if-linux.c

@@ -752,6 +752,11 @@ if_copyrt(struct dhcpcd_ctx *ctx, struct rt *rt, struct nlmsghdr *nlm)
 			}
 			break;
 		}
+		case RTA_EXPIRES:
+		{
+			rt->rt_expires = *(uint32_t *)RTA_DATA(rta);
+			break;
+		}
 		}
 
 		if (sa != NULL) {
@@ -1735,6 +1740,10 @@ 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);
+
 	if (rt->rt_metric != 0)
 		add_attr_32(&nlm.hdr, sizeof(nlm), RTA_PRIORITY,
 		    rt->rt_metric);

src/ipv6.c

@@ -2301,10 +2301,13 @@ inet6_raroutes(rb_tree_t *routes, struct dhcpcd_ctx *ctx)
 	const struct routeinfo *rinfo;
 	const struct ipv6_addr *addr;
 	struct in6_addr netmask;
+	struct timespec now;
 
 	if (ctx->ra_routers == NULL)
 		return 0;
 
+	clock_gettime(CLOCK_MONOTONIC, &now);
+
 	TAILQ_FOREACH(rap, ctx->ra_routers, next) {
 		if (rap->expired)
 			continue;
@@ -2325,6 +2328,7 @@ 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, &rinfo->acquired, &now);
 
 			rt_proto_add(routes, rt);
 		}
@@ -2339,6 +2343,8 @@ 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(addr->prefix_vltime, &addr->acquired, &now);
+
 				rt_proto_add(routes, rt);
 			}
 		}
@@ -2370,6 +2376,8 @@ 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, &rap->acquired, &now);
+
 		rt_proto_add(routes, rt);
 	}
 	return 0;

src/route.h

@@ -120,6 +120,7 @@ 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 */
 };
 
 extern const rb_tree_ops_t rt_compare_list_ops;