implemented a monotonic timestamping function, unaffected from system time changes

configure.in

@@ -908,6 +908,12 @@ AC_SEARCH_LIBS(socket, socket, [SOCKLIB=$LIBS],
 )
 AC_SUBST(SOCKLIB)
 
+dnl FreeBSD has clock_gettime in libc, Linux needs librt
+LIBS=""
+AC_SEARCH_LIBS(clock_gettime, rt, [RTLIB=$LIBS])
+AC_CHECK_FUNCS(clock_gettime)
+AC_SUBST(RTLIB)
+
 LIBS=$saved_LIBS
 dnl ======================
 

src/libstrongswan/Makefile.am

@@ -49,7 +49,7 @@ utils/mutex.c utils/mutex.h \
 utils/backtrace.c utils/backtrace.h \
 plugins/plugin_loader.c plugins/plugin_loader.h plugins/plugin.h
 
-libstrongswan_la_LIBADD = -lpthread $(DLLIB) $(BTLIB) $(SOCKLIB)
+libstrongswan_la_LIBADD = -lpthread $(DLLIB) $(BTLIB) $(SOCKLIB) $(RTLIB)
 
 INCLUDES = -I$(top_srcdir)/src/libstrongswan
 AM_CFLAGS = \

src/libstrongswan/utils.c

@@ -162,6 +162,39 @@ bool mkdir_p(const char *path, mode_t mode)
 	return TRUE;
 }
 
+/**
+ * Return monotonic time
+ */
+time_t time_monotonic(timeval_t *tv)
+{
+#if defined(HAVE_CLOCK_GETTIME)
+	timespec_t ts;
+	
+	if (clock_gettime(CLOCK_MONOTONIC, &ts) == 0)
+	{
+		if (tv)
+		{
+			tv->tv_sec = ts.tv_sec;
+			tv->tv_usec = ts.tv_nsec / 1000;
+		}
+		return ts.tv_sec;
+	}
+#endif /* HAVE_CLOCK_MONOTONIC */
+	/* Fallback to non-monotonic timestamps:
+	 * On MAC OS X, creating monotonic timestamps is rather difficult. We
+	 * could use mach_absolute_time() and catch sleep/wakeup notifications.
+	 * We stick to the simpler (non-monotonic) gettimeofday() for now. */
+	if (!tv)
+	{
+		return time(NULL);
+	}
+	if (gettimeofday(tv, NULL) != 0)
+	{	/* should actually never fail if passed pointers are valid */
+		return -1;
+	}
+	return tv->tv_sec;
+}
+
 /**
  * return null
  */

src/libstrongswan/utils.h

@@ -25,6 +25,7 @@
 #include <sys/types.h>
 #include <stdlib.h>
 #include <stddef.h>
+#include <sys/time.h>
 
 #include <enum.h>
 
@@ -269,12 +270,24 @@ void *memstr(const void *haystack, const char *needle, size_t n);
 /**
  * Creates a directory and all required parent directories. 
  *
- * @param	path	path to the new directory
- * @param	mode	permissions of the new directory/directories 
+ * @param path		path to the new directory
+ * @param mode		permissions of the new directory/directories 
  * @return			TRUE on success
  */
 bool mkdir_p(const char *path, mode_t mode);
 
+/**
+ * Get a timestamp from a monotonic time source.
+ *
+ * While the time()/gettimeofday() functions are affected by leap seconds
+ * and system time changes, this function returns ever increasing monotonic
+ * time stamps.
+ *
+ * @param tv		timeval struct receiving monotonic timestamps, or NULL
+ * @return			monotonic timestamp in seconds
+ */
+time_t time_monotonic(timeval_t *tv);
+
 /**
  * returns null
  */