From c33e40cce15c6cb3ea1892e678fa3acb3e808107 Mon Sep 17 00:00:00 2001
From: Martine Lenders <m.lenders@fu-berlin.de>
Date: Wed, 4 Aug 2021 12:36:10 +0200
Subject: [PATCH] gnrc_ipv6_nib: provide functions to get offset of public
 timestamps

---
 sys/include/net/gnrc/ipv6/nib/abr.h | 21 +++++++++++++++
 sys/include/net/gnrc/ipv6/nib/pl.h  | 42 +++++++++++++++++++++++++++++
 2 files changed, 63 insertions(+)

diff --git a/sys/include/net/gnrc/ipv6/nib/abr.h b/sys/include/net/gnrc/ipv6/nib/abr.h
index dd9dbd4e3b..3514912eb5 100644
--- a/sys/include/net/gnrc/ipv6/nib/abr.h
+++ b/sys/include/net/gnrc/ipv6/nib/abr.h
@@ -23,6 +23,11 @@
 
 #include <kernel_defines.h>
 
+/* prevent cascading include error to xtimer if it is not compiled in or not
+ * supported by board */
+#if IS_USED(MODULE_EVTIMER)
+#include "evtimer.h"
+#endif
 #include "net/ipv6/addr.h"
 #include "net/gnrc/ipv6/nib/conf.h"
 
@@ -99,6 +104,22 @@ void gnrc_ipv6_nib_abr_del(const ipv6_addr_t *addr);
  */
 bool gnrc_ipv6_nib_abr_iter(void **state, gnrc_ipv6_nib_abr_t *abr);
 
+#if IS_USED(MODULE_EVTIMER) || defined(DOXYGEN)
+/**
+ * @brief   Provides the time in minutes for which the authoritative border
+ *          router entry is valid
+ *
+ * @param[in] abr   An authoritative border router entry.
+ *
+ * @return  The time in minutes for which the authoritative border router entry
+ *          is valid.
+ */
+static inline uint32_t gnrc_ipv6_nib_abr_valid_offset(const gnrc_ipv6_nib_abr_t *abr)
+{
+    return abr->valid_until - evtimer_now_min();
+}
+#endif
+
 /**
  * @brief   Prints an authoritative border router list entry
  *
diff --git a/sys/include/net/gnrc/ipv6/nib/pl.h b/sys/include/net/gnrc/ipv6/nib/pl.h
index b18ba6fc55..aebc798d4f 100644
--- a/sys/include/net/gnrc/ipv6/nib/pl.h
+++ b/sys/include/net/gnrc/ipv6/nib/pl.h
@@ -22,6 +22,9 @@
 
 #include <stdint.h>
 
+#if IS_USED(MODULE_EVTIMER)
+#include "evtimer.h"
+#endif
 #include "net/ipv6/addr.h"
 
 #ifdef __cplusplus
@@ -122,6 +125,45 @@ void gnrc_ipv6_nib_pl_del(unsigned iface,
 bool gnrc_ipv6_nib_pl_iter(unsigned iface, void **state,
                            gnrc_ipv6_nib_pl_t *ple);
 
+#if IS_USED(MODULE_EVTIMER) || defined(DOXYGEN)
+/**
+ * @brief   Provides the time in milliseconds for which the prefix list
+ *          entry is valid
+ *
+ * @param[in] ple   A prefix list entry.
+ *
+ * @return  The time in milliseconds for which the prefix list entry is valid.
+ *          UINT32_MAX if it is valid forever.
+ */
+static inline uint32_t gnrc_ipv6_nib_pl_valid_offset(const gnrc_ipv6_nib_pl_t *ple)
+{
+
+    return (ple->valid_until == UINT32_MAX)
+        ? UINT32_MAX
+        : (ple->valid_until - evtimer_now_msec());
+}
+
+/**
+ * @brief   Provides the time in milliseconds for which the prefix list
+ *          entry is preferred
+ *
+ * A prefix for which the preference expired is deprecated (see [RFC 4862]
+ * (https://tools.ietf.org/html/rfc4862))
+ *
+ * @param[in] ple   A prefix list entry.
+ *
+ * @return  The time in milliseconds for which the prefix list entry is
+ *          preferred. UINT32_MAX if it is preferred forever.
+ */
+static inline uint32_t gnrc_ipv6_nib_pl_pref_offset(const gnrc_ipv6_nib_pl_t *ple)
+{
+
+    return (ple->pref_until == UINT32_MAX)
+        ? UINT32_MAX
+        : (ple->pref_until - evtimer_now_msec());
+}
+#endif
+
 /**
  * @brief   Prints a prefix list entry
  *