From 709d6710d047566c71f03e579a02c3d99fe15a3e Mon Sep 17 00:00:00 2001
From: Patrik Flykt <patrik.flykt@linux.intel.com>
Date: Wed, 25 Jun 2014 15:37:58 +0300
Subject: [PATCH] sd-dhcp6-lease: Add helper function to compute remaining
 expiry time

Create a helper function to compute the remaining time in seconds from
time T2 to the IPv6 address with the longest lifetime. The computed
time is used as the Maximum Retransmission Duration in Rebinding state.
See RFC 3315, section 18.1.4. for details.
---
 src/libsystemd-network/dhcp6-lease-internal.h |  1 +
 src/libsystemd-network/sd-dhcp6-lease.c       | 22 +++++++++++++++++++
 2 files changed, 23 insertions(+)

diff --git a/src/libsystemd-network/dhcp6-lease-internal.h b/src/libsystemd-network/dhcp6-lease-internal.h
index 295c2232075..62c16c5b6d2 100644
--- a/src/libsystemd-network/dhcp6-lease-internal.h
+++ b/src/libsystemd-network/dhcp6-lease-internal.h
@@ -42,6 +42,7 @@ struct sd_dhcp6_lease {
 };
 
 int dhcp6_lease_clear_timers(DHCP6IA *ia);
+int dhcp6_lease_ia_rebind_expire(const DHCP6IA *ia, uint32_t *expire);
 DHCP6IA *dhcp6_lease_free_ia(DHCP6IA *ia);
 
 int dhcp6_lease_set_serverid(sd_dhcp6_lease *lease, const uint8_t *id,
diff --git a/src/libsystemd-network/sd-dhcp6-lease.c b/src/libsystemd-network/sd-dhcp6-lease.c
index cbda7d8c84b..17a4b640631 100644
--- a/src/libsystemd-network/sd-dhcp6-lease.c
+++ b/src/libsystemd-network/sd-dhcp6-lease.c
@@ -33,6 +33,28 @@ int dhcp6_lease_clear_timers(DHCP6IA *ia) {
         return 0;
 }
 
+int dhcp6_lease_ia_rebind_expire(const DHCP6IA *ia, uint32_t *expire) {
+        DHCP6Address *addr;
+        uint32_t valid = 0, t;
+
+        assert_return(ia, -EINVAL);
+        assert_return(expire, -EINVAL);
+
+        LIST_FOREACH(addresses, addr, ia->addresses) {
+                t = be32toh(addr->lifetime_valid);
+                if (valid < t)
+                        valid = t;
+        }
+
+        t = be32toh(ia->lifetime_t2);
+        if (t > valid)
+                return -EINVAL;
+
+        *expire = valid - t;
+
+        return 0;
+}
+
 DHCP6IA *dhcp6_lease_free_ia(DHCP6IA *ia) {
         DHCP6Address *address;