Suck it hard and use gettimeofday for Linux. Lets just hope that the clock works under Linux during ARP floods.

ChangeLog

@@ -1,6 +1,6 @@
 dhcpcd-3.1.5
 Fix the flushing of addresses on BSD systems.
-Rework the arp code again so that we don't link to librt on Linux.
+Rework get_time so that we don't link to librt on Linux.
 Thanks to regenrecht for reporting the below three overflows:-
  Fix a potential buffer overflow in hwaddr_ntoa if length > 42.
  Fix a potential heap overflow in decode_CSR when CIDR > 32.

arp.c

@@ -104,11 +104,6 @@ int arp_claim (interface_t *iface, struct in_addr address)
 	int nclaims = 0;
 	struct in_addr null_address;
 
-#ifdef HAVE_GET_TIME
-	struct timeval stopat;
-	struct timeval now;
-#endif
-
 	if (! iface)
 		return (-1);
 
@@ -135,6 +130,8 @@ int arp_claim (interface_t *iface, struct in_addr address)
 		fd_set rset;
 		int bytes;
 		int s = 0;
+		struct timeval stopat;
+		struct timeval now;
 
 		/* Only select if we have a timeout */
 		if (timeout > 0) {
@@ -170,32 +167,21 @@ int arp_claim (interface_t *iface, struct in_addr address)
 				break;
 			}
 
-
-#ifdef HAVE_GET_TIME
 			/* Setup our stop time */
 			if (get_time (&stopat) != 0)
 				break;
 			stopat.tv_usec += timeout;
-#endif
 
 			continue;
 		}
 
-		/* Check for ARP floods */
-#ifdef __linux__
-		/* Linux does modify the tv struct, otherwise we would have to link
-		 * into librt to use get get_time function */
-		timeout = tv.tv_usec;
-		if (timeout <= 0)
-			continue;
-#else
+		/* We maybe ARP flooded, so check our time */
 		if (get_time (&now) != 0)
 			break;
 		if (timercmp (&now, &stopat, >)) {
 			timeout = 0;
 			continue;
 		}
-#endif
 
 		if (! FD_ISSET (iface->fd, &rset))
 			continue;

common.c

@@ -79,6 +79,8 @@ size_t strlcpy (char *dst, const char *src, size_t size)
 /* This requires us to link to rt on glibc, so we use sysinfo instead */
 #ifdef __linux__
 #include <sys/sysinfo.h>
+/* Avoid clock_gettime as it requires librt on Linux */
+#undef CLOCK_MONOTONIC
 long uptime (void)
 {
 	struct sysinfo info;
@@ -86,7 +88,19 @@ long uptime (void)
 	sysinfo (&info);
 	return info.uptime;
 }
-#elif __APPLE__
+#elif CLOCK_MONOTONIC
+long uptime (void)
+{
+	struct timespec tp;
+
+	if (clock_gettime (CLOCK_MONOTONIC, &tp) == -1) {
+		logger (LOG_ERR, "clock_gettime: %s", strerror (errno));
+		return -1;
+	}
+
+	return tp.tv_sec;
+}
+#else
 /* Darwin doesn't appear to have an uptime, so try and make one ourselves */
 long uptime (void)
 {
@@ -103,27 +117,14 @@ long uptime (void)
 
 	return tv.tv_sec - start;
 }
-#else
-long uptime (void)
-{
-	struct timespec tp;
-
-	if (clock_gettime (CLOCK_MONOTONIC, &tp) == -1) {
-		logger (LOG_ERR, "clock_gettime: %s", strerror (errno));
-		return -1;
-	}
-
-	return tp.tv_sec;
-}
 #endif
 
 /* Handy function to get the time.
  * We only care about time advancements, not the actual time itself
  * Which is why we use CLOCK_MONOTONIC, but it is not available on all
- * platforms
+ * platforms.
  */
-#ifdef HAVE_GET_TIME 
-# ifdef CLOCK_MONOTONIC
+#ifdef CLOCK_MONOTONIC 
 int get_time (struct timeval *tp)
 {
 	struct timespec ts;
@@ -137,16 +138,15 @@ int get_time (struct timeval *tp)
 	tp->tv_usec = ts.tv_nsec / 1000;
 	return (0);
 }
-# else
+#else
 int get_time (struct timeval *tp)
 {
-	if (gettimeofday (&tp, NULL) == -1) {
+	if (gettimeofday (tp, NULL) == -1) {
 		logger (LOG_ERR, "gettimeofday: %s", strerror (errno));
 		return (-1);
 	}
 	return (0);
 }
-# endif
 #endif
 
 void *xmalloc (size_t s)

common.h

@@ -35,11 +35,9 @@ size_t strlcpy (char *dst, const char *src, size_t size);
 
 #ifdef __linux__
 void srandomdev (void);
-#else
-#define HAVE_GET_TIME
-int get_time (struct timeval *tp);
 #endif
 
+int get_time (struct timeval *tp);
 long uptime (void);
 void *xmalloc (size_t size);
 char *xstrdup (const char *str);