1 files changed, 123 insertions, 3 deletions

diff --git a/src/util/time.c b/src/util/time.c
index b02c43c1b..46d3a2b65 100644
--- a/src/util/time.c
+++ b/src/util/time.c
@@ -1,6 +1,6 @@
 /*
      This file is part of GNUnet.
-     Copyright (C) 2001-2013 GNUnet e.V.
+     Copyright (C) 2001-2013, 2018 GNUnet e.V.
 
      GNUnet is free software: you can redistribute it and/or modify it
      under the terms of the GNU Affero General Public License as published
@@ -22,8 +22,7 @@
  * @brief functions for handling time and time arithmetic
  */
 #include "platform.h"
-#include "gnunet_crypto_lib.h"
-#include "gnunet_time_lib.h"
+#include "gnunet_util_lib.h"
 
 #define LOG(kind,...) GNUNET_log_from (kind, "util-time", __VA_ARGS__)
 
@@ -757,6 +756,127 @@ GNUNET_TIME_randomized_backoff(struct GNUNET_TIME_Relative rt, struct GNUNET_TIM
 }
 
 
+/**
+ * Obtain the current time and make sure it is monotonically
+ * increasing.  Guards against systems without an RTC or
+ * clocks running backwards and other nasty surprises. Does
+ * not guarantee that the returned time is near the current
+ * time returned by #GNUNET_TIME_absolute_get().  Two 
+ * subsequent calls (within a short time period) may return the
+ * same value. Persists the last returned time on disk to
+ * ensure that time never goes backwards. As a result, the
+ * resulting value can be used to check if a message is the 
+ * "most recent" value and replays of older messages (from
+ * the same origin) would be discarded.
+ * 
+ * @param cfg configuration, used to determine where to 
+ *   store the time; user can also insist RTC is working
+ *   nicely and disable the feature
+ * @return monotonically increasing time
+ */
+struct GNUNET_TIME_Absolute
+GNUNET_TIME_absolute_get_monotonic (const struct GNUNET_CONFIGURATION_Handle *cfg)
+{
+  static const struct GNUNET_CONFIGURATION_Handle *last_cfg;
+  static struct GNUNET_TIME_Absolute last_time;
+  static struct GNUNET_DISK_MapHandle *map_handle;
+  static struct GNUNET_TIME_AbsoluteNBO *map;
+  struct GNUNET_TIME_Absolute now;
+
+  now = GNUNET_TIME_absolute_get ();
+  if (last_cfg != cfg)
+  {
+    char *filename;
+
+    if (NULL != map_handle)
+    {
+      GNUNET_DISK_file_unmap (map_handle);
+      map_handle = NULL;
+    }
+    map = NULL;
+    
+    last_cfg = cfg;
+    if ( (NULL != cfg) &&
+         (GNUNET_OK ==
+          GNUNET_CONFIGURATION_get_value_filename (cfg,
+                                                   "util",
+                                                   "MONOTONIC_TIME_FILENAME",
+                                                   &filename)) )
+    {
+      struct GNUNET_DISK_FileHandle *fh;
+
+      fh = GNUNET_DISK_file_open (filename,
+                                  GNUNET_DISK_OPEN_READWRITE | GNUNET_DISK_OPEN_CREATE,
+                                  GNUNET_DISK_PERM_USER_WRITE | GNUNET_DISK_PERM_GROUP_WRITE |
+                                  GNUNET_DISK_PERM_USER_READ  | GNUNET_DISK_PERM_GROUP_READ);
+      if (NULL == fh)
+      {
+        GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                    _("Failed to map `%s', cannot assure monotonic time!\n"),
+                    filename);
+      }
+      else
+      { 
+        off_t size;
+
+        size = 0;
+        GNUNET_break (GNUNET_OK ==
+                      GNUNET_DISK_file_handle_size (fh,
+                                                    &size));
+        if (size < sizeof (*map))
+        {
+          struct GNUNET_TIME_AbsoluteNBO o;
+
+          o = GNUNET_TIME_absolute_hton (now);
+          if (sizeof (o) !=
+              GNUNET_DISK_file_write (fh,
+                                      &o,
+                                      sizeof (o)))
+            size = 0;
+          else
+            size = sizeof (o);
+        }
+        if (size == sizeof (*map))
+        {
+          map = GNUNET_DISK_file_map (fh,
+                                      &map_handle,
+                                      GNUNET_DISK_MAP_TYPE_READWRITE,
+                                      sizeof (*map));
+          if (NULL == map)
+            GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                        _("Failed to map `%s', cannot assure monotonic time!\n"),
+                        filename);
+        }
+        else
+        {
+          GNUNET_log (GNUNET_ERROR_TYPE_WARNING,
+                      _("Failed to setup monotonic time file `%s', cannot assure monotonic time!\n"),
+                      filename);
+        }
+      }
+      GNUNET_DISK_file_close (fh);
+      GNUNET_free (filename);
+    }
+  }
+  if (NULL != map)
+    last_time = GNUNET_TIME_absolute_max (GNUNET_TIME_absolute_ntoh (*map),
+                                          last_time);
+  if (now.abs_value_us <= last_time.abs_value_us)
+    now.abs_value_us = last_time.abs_value_us+1;
+  last_time = now;
+  if (NULL != map)
+    *map = GNUNET_TIME_absolute_hton (now);
+  return now;
+}
+
 
+/**
+ * Destructor
+ */
+void __attribute__ ((destructor))
+GNUNET_util_time_fini ()
+{
+  (void) GNUNET_TIME_absolute_get_monotonic (NULL);
+}
 
 /* end of time.c */