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authorAlberto Gonzalez Iniesta <agi@inittab.org>2012-02-21 15:53:40 +0100
committerAlberto Gonzalez Iniesta <agi@inittab.org>2012-02-21 15:53:40 +0100
commit349cfa7acb95abe865209a28e417ec74b56f9bba (patch)
treead65334821b587c4ecdd461be84c94305ffdb888 /otime.c
Imported Upstream version 2.2.1upstream/2.2.1
Diffstat (limited to 'otime.c')
-rw-r--r--otime.c273
1 files changed, 273 insertions, 0 deletions
diff --git a/otime.c b/otime.c
new file mode 100644
index 0000000..b295646
--- /dev/null
+++ b/otime.c
@@ -0,0 +1,273 @@
+/*
+ * OpenVPN -- An application to securely tunnel IP networks
+ * over a single TCP/UDP port, with support for SSL/TLS-based
+ * session authentication and key exchange,
+ * packet encryption, packet authentication, and
+ * packet compression.
+ *
+ * Copyright (C) 2002-2010 OpenVPN Technologies, Inc. <sales@openvpn.net>
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 2
+ * as published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program (see the file COPYING included with this
+ * distribution); if not, write to the Free Software Foundation, Inc.,
+ * 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ */
+
+#include "syshead.h"
+
+#include "otime.h"
+
+#include "memdbg.h"
+
+time_t now = 0; /* GLOBAL */
+
+#if TIME_BACKTRACK_PROTECTION && defined(HAVE_GETTIMEOFDAY)
+
+static time_t now_adj = 0; /* GLOBAL */
+time_t now_usec = 0; /* GLOBAL */
+
+/*
+ * Try to filter out time instability caused by the system
+ * clock backtracking or jumping forward.
+ */
+
+void
+update_now (const time_t system_time)
+{
+ const int forward_threshold = 86400; /* threshold at which to dampen forward jumps */
+ const int backward_trigger = 10; /* backward jump must be >= this many seconds before we adjust */
+ time_t real_time = system_time + now_adj;
+
+ if (real_time > now)
+ {
+ const time_t overshoot = real_time - now - 1;
+ if (overshoot > forward_threshold && now_adj >= overshoot)
+ {
+ now_adj -= overshoot;
+ real_time -= overshoot;
+ }
+ now = real_time;
+ }
+ else if (real_time < now - backward_trigger)
+ now_adj += (now - real_time);
+}
+
+void
+update_now_usec (struct timeval *tv)
+{
+ const time_t last = now;
+ update_now (tv->tv_sec);
+ if (now > last || (now == last && tv->tv_usec > now_usec))
+ now_usec = tv->tv_usec;
+}
+
+#endif /* TIME_BACKTRACK_PROTECTION && defined(HAVE_GETTIMEOFDAY) */
+
+/*
+ * Return a numerical string describing a struct timeval.
+ */
+const char *
+tv_string (const struct timeval *tv, struct gc_arena *gc)
+{
+ struct buffer out = alloc_buf_gc (64, gc);
+ buf_printf (&out, "[%d/%d]",
+ (int) tv->tv_sec,
+ (int )tv->tv_usec);
+ return BSTR (&out);
+}
+
+/*
+ * Return an ascii string describing an absolute
+ * date/time in a struct timeval.
+ *
+ */
+const char *
+tv_string_abs (const struct timeval *tv, struct gc_arena *gc)
+{
+ return time_string ((time_t) tv->tv_sec,
+ (int) tv->tv_usec,
+ true,
+ gc);
+}
+
+/* format a time_t as ascii, or use current time if 0 */
+
+const char *
+time_string (time_t t, int usec, bool show_usec, struct gc_arena *gc)
+{
+ struct buffer out = alloc_buf_gc (64, gc);
+ struct timeval tv;
+
+ if (t)
+ {
+ tv.tv_sec = t;
+ tv.tv_usec = usec;
+ }
+ else
+ {
+#ifdef HAVE_GETTIMEOFDAY
+ if (gettimeofday (&tv, NULL))
+#endif
+ {
+ tv.tv_sec = time (NULL);
+ tv.tv_usec = 0;
+ }
+ }
+
+ t = tv.tv_sec;
+ buf_printf (&out, "%s", ctime(&t));
+ buf_rmtail (&out, '\n');
+
+ if (show_usec && tv.tv_usec)
+ buf_printf (&out, " us=%d", (int)tv.tv_usec);
+
+ return BSTR (&out);
+}
+
+/*
+ * Limit the frequency of an event stream.
+ *
+ * Used to control maximum rate of new
+ * incoming connections.
+ */
+
+struct frequency_limit *
+frequency_limit_init (int max, int per)
+{
+ struct frequency_limit *f;
+
+ ASSERT (max >= 0 && per >= 0);
+
+ ALLOC_OBJ (f, struct frequency_limit);
+ f->max = max;
+ f->per = per;
+ f->n = 0;
+ f->reset = 0;
+ return f;
+}
+
+void
+frequency_limit_free (struct frequency_limit *f)
+{
+ free (f);
+}
+
+bool
+frequency_limit_event_allowed (struct frequency_limit *f)
+{
+ if (f->per)
+ {
+ bool ret;
+ if (now >= f->reset + f->per)
+ {
+ f->reset = now;
+ f->n = 0;
+ }
+ ret = (++f->n <= f->max);
+ return ret;
+ }
+ else
+ return true;
+}
+
+#ifdef WIN32
+
+static time_t gtc_base = 0;
+static DWORD gtc_last = 0;
+static time_t last_sec = 0;
+static unsigned int last_msec = 0;
+static bool bt_last = false;
+
+static void
+gettimeofday_calibrate (void)
+{
+ const time_t t = time(NULL);
+ const DWORD gtc = GetTickCount();
+ gtc_base = t - gtc/1000;
+ gtc_last = gtc;
+}
+
+/*
+ * Rewritten by JY for OpenVPN 2.1, after I realized that
+ * QueryPerformanceCounter takes nearly 2 orders of magnitude
+ * more processor cycles than GetTickCount.
+ */
+int
+gettimeofday (struct timeval *tv, void *tz)
+{
+ const DWORD gtc = GetTickCount();
+ bool bt = false;
+ time_t sec;
+ unsigned int msec;
+ const int backtrack_hold_seconds = 10;
+
+ /* recalibrate at the dreaded 49.7 day mark */
+ if (!gtc_base || gtc < gtc_last)
+ gettimeofday_calibrate ();
+ gtc_last = gtc;
+
+ sec = gtc_base + gtc / 1000;
+ msec = gtc % 1000;
+
+ if (sec == last_sec)
+ {
+ if (msec < last_msec)
+ {
+ msec = last_msec;
+ bt = true;
+ }
+ }
+ else if (sec < last_sec)
+ {
+ /* We try to dampen out backtracks of less than backtrack_hold_seconds.
+ Larger backtracks will be passed through and dealt with by the
+ TIME_BACKTRACK_PROTECTION code (if enabled) */
+ if (sec > last_sec - backtrack_hold_seconds)
+ {
+ sec = last_sec;
+ msec = last_msec;
+ }
+ bt = true;
+ }
+
+ tv->tv_sec = last_sec = sec;
+ tv->tv_usec = (last_msec = msec) * 1000;
+
+ if (bt && !bt_last)
+ gettimeofday_calibrate ();
+ bt_last = bt;
+
+ return 0;
+}
+
+#endif /* WIN32 */
+
+#ifdef TIME_TEST
+void
+time_test (void)
+{
+ struct timeval tv;
+ time_t t;
+ int i;
+ for (i = 0; i < 10000; ++i)
+ {
+ t = time(NULL);
+ gettimeofday (&tv, NULL);
+#if 1
+ msg (M_INFO, "t=%u s=%u us=%u",
+ (unsigned int)t,
+ (unsigned int)tv.tv_sec,
+ (unsigned int)tv.tv_usec);
+#endif
+ }
+}
+#endif