eloop: Allow for for timeouts greater than time_t and time wrapping

On some systems time_t is int32_t.
However, on wire timeouts are generally uint32_t.
As such, we need to avoid using timespec internally except to
record when the timeout was created. Instead, record the timeout
as unsigned int seconds and long nanoseconds.

On long running systems using time_t as int32_t, monotonic time
would wrap after approximately 68 years. It's highly unlikely dhcpcd
would be running for so long, but just incase it does, the code
should now cope.

1 files changed, 24 insertions, 33 deletions

diff --git a/src/ipv6nd.c b/src/ipv6nd.c
index f3899b83..ae057795 100644
--- a/src/ipv6nd.c
+++ b/src/ipv6nd.c
@@ -1594,7 +1594,7 @@ ipv6nd_expirera(void *arg)
 {
 	struct interface *ifp;
 	struct ra *rap, *ran;
-	struct timespec now, lt, expire, next;
+	struct timespec now, expire;
 	bool expired, valid;
 	struct ipv6_addr *ia;
 	size_t len, olen;
@@ -1605,23 +1605,20 @@ ipv6nd_expirera(void *arg)
 #endif
 	struct nd_opt_dnssl dnssl;
 	struct nd_opt_rdnss rdnss;
-	uint32_t ltime;
+	unsigned int next = 0, ltime;
 	size_t nexpired = 0;
 
 	ifp = arg;
 	clock_gettime(CLOCK_MONOTONIC, &now);
 	expired = false;
-	timespecclear(&next);
 
 	TAILQ_FOREACH_SAFE(rap, ifp->ctx->ra_routers, next, ran) {
 		if (rap->iface != ifp || rap->expired)
 			continue;
 		valid = false;
 		if (rap->lifetime) {
-			lt.tv_sec = (time_t)rap->lifetime;
-			lt.tv_nsec = 0;
-			timespecadd(&rap->acquired, &lt, &expire);
-			if (timespeccmp(&now, &expire, >)) {
+			timespecsub(&now, &rap->acquired, &expire);
+			if (expire.tv_sec > rap->lifetime) {
 				if (!rap->expired) {
 					logwarnx("%s: %s: router expired",
 					    ifp->name, rap->sfrom);
@@ -1630,10 +1627,10 @@ ipv6nd_expirera(void *arg)
 				}
 			} else {
 				valid = true;
-				timespecsub(&expire, &now, &lt);
-				if (!timespecisset(&next) ||
-				    timespeccmp(&next, &lt, >))
-					next = lt;
+				ltime = (unsigned int)
+				    (rap->lifetime - expire.tv_sec);
+				if (next == 0 || ltime < next)
+					next = ltime;
 			}
 		}
 
@@ -1647,10 +1644,8 @@ ipv6nd_expirera(void *arg)
 				valid = true;
 				continue;
 			}
-			lt.tv_sec = (time_t)ia->prefix_vltime;
-			lt.tv_nsec = 0;
-			timespecadd(&ia->acquired, &lt, &expire);
-			if (timespeccmp(&now, &expire, >)) {
+			timespecsub(&now, &ia->acquired, &expire);
+			if (expire.tv_sec > ia->prefix_vltime) {
 				if (ia->flags & IPV6_AF_ADDED) {
 					logwarnx("%s: expired address %s",
 					    ia->iface->name, ia->saddr);
@@ -1664,15 +1659,16 @@ ipv6nd_expirera(void *arg)
 				    ~(IPV6_AF_ADDED | IPV6_AF_DADCOMPLETED);
 				expired = true;
 			} else {
-				timespecsub(&expire, &now, &lt);
-				if (!timespecisset(&next) ||
-				    timespeccmp(&next, &lt, >))
-					next = lt;
 				valid = true;
+				ltime = (unsigned int)
+				    (ia->prefix_vltime - expire.tv_sec);
+				if (next == 0 || ltime < next)
+					next = ltime;
 			}
 		}
 
 		/* Work out expiry for ND options */
+		timespecsub(&now, &rap->acquired, &expire);
 		len = rap->data_len - sizeof(struct nd_router_advert);
 		for (p = rap->data + sizeof(struct nd_router_advert);
 		    len >= sizeof(ndo);
@@ -1722,21 +1718,16 @@ ipv6nd_expirera(void *arg)
 				continue;
 			}
 
-			lt.tv_sec = (time_t)ntohl(ltime);
-			lt.tv_nsec = 0;
-			timespecadd(&rap->acquired, &lt, &expire);
-			if (timespeccmp(&now, &expire, >)) {
+			ltime = ntohl(ltime);
+			if (expire.tv_sec > ltime) {
 				expired = true;
 				continue;
 			}
 
-			timespecsub(&expire, &now, &lt);
-			if (!timespecisset(&next) ||
-			    timespeccmp(&next, &lt, >))
-			{
-				next = lt;
-				valid = true;
-			}
+			valid = true;
+			ltime = (unsigned int)(ltime - expire.tv_sec);
+			if (next == 0 || ltime < next)
+				next = ltime;
 		}
 
 		if (valid)
@@ -1748,9 +1739,9 @@ ipv6nd_expirera(void *arg)
 			ipv6nd_free_ra(rap);
 	}
 
-	if (timespecisset(&next))
-		eloop_timeout_add_tv(ifp->ctx->eloop,
-		    &next, ipv6nd_expirera, ifp);
+	if (next != 0)
+		eloop_timeout_add_sec(ifp->ctx->eloop,
+		    next, ipv6nd_expirera, ifp);
 	if (expired) {
 		logwarnx("%s: part of Router Advertisement expired", ifp->name);
 		rt_build(ifp->ctx, AF_INET6);