[#1418] Checkpoint: small improvements

5 files changed, 112 insertions, 24 deletions

diff --git a/src/bin/dhcp6/dhcp6_srv.cc b/src/bin/dhcp6/dhcp6_srv.cc
index 656d291c04..cbae8670f3 100644
--- a/src/bin/dhcp6/dhcp6_srv.cc
+++ b/src/bin/dhcp6/dhcp6_srv.cc
@@ -2072,9 +2072,8 @@ Dhcpv6Srv::assignIA_NA(const Pkt6Ptr& query, const Pkt6Ptr& answer,
                 .arg(ia->getIAID())
                 .arg(Lease::lifetimeToText(lease->valid_lft_));
         } else {
-            auto age = lease->valid_lft_ - lease->remaining_valid_lft_;
             lease->valid_lft_ = lease->remaining_valid_lft_;
-            lease->preferred_lft_ -= age;
+            lease->preferred_lft_ = lease->remaining_preferred_lft_;
             LOG_INFO(lease6_logger, DHCP6_LEASE_REUSE)
                 .arg(query->getLabel())
                 .arg(lease->addr_.toText())
@@ -2198,9 +2197,8 @@ Dhcpv6Srv::assignIA_PD(const Pkt6Ptr& query, const Pkt6Ptr& /*answer*/,
                     .arg(ia->getIAID())
                     .arg(Lease::lifetimeToText((*l)->valid_lft_));
             } else {
-                auto age = (*l)->valid_lft_ - (*l)->remaining_valid_lft_;
                 (*l)->valid_lft_ = (*l)->remaining_valid_lft_;
-                (*l)->preferred_lft_ -= age;
+                (*l)->preferred_lft_ = (*l)->remaining_preferred_lft_;
                 LOG_INFO(lease6_logger, DHCP6_PD_LEASE_REUSE)
                     .arg(query->getLabel())
                     .arg((*l)->addr_.toText())
@@ -2357,9 +2355,8 @@ Dhcpv6Srv::extendIA_NA(const Pkt6Ptr& query, const Pkt6Ptr& answer,
                 .arg((*l)->addr_.toText())
                 .arg(ia->getIAID());
         } else {
-            auto age = (*l)->valid_lft_ - (*l)->remaining_valid_lft_;
             (*l)->valid_lft_ = (*l)->remaining_valid_lft_;
-            (*l)->preferred_lft_ -= age;
+            (*l)->preferred_lft_ = (*l)->remaining_preferred_lft_;
             LOG_INFO(lease6_logger, DHCP6_LEASE_REUSE)
                 .arg(query->getLabel())
                 .arg((*l)->addr_.toText())
@@ -2563,9 +2560,8 @@ Dhcpv6Srv::extendIA_PD(const Pkt6Ptr& query,
                 .arg(static_cast<int>((*l)->prefixlen_))
                 .arg(ia->getIAID());
         } else {
-            auto age = (*l)->valid_lft_ - (*l)->remaining_valid_lft_;
             (*l)->valid_lft_ = (*l)->remaining_valid_lft_;
-            (*l)->preferred_lft_ -= age;
+            (*l)->preferred_lft_ = (*l)->remaining_preferred_lft_;
             LOG_INFO(lease6_logger, DHCP6_PD_LEASE_REUSE)
                 .arg(query->getLabel())
                 .arg((*l)->addr_.toText())
diff --git a/src/lib/dhcpsrv/alloc_engine.cc b/src/lib/dhcpsrv/alloc_engine.cc
index 9718d10580..53b5456047 100644
--- a/src/lib/dhcpsrv/alloc_engine.cc
+++ b/src/lib/dhcpsrv/alloc_engine.cc
@@ -4362,25 +4362,29 @@ AllocEngine::updateLease6ExtendedInfo(const Lease6Ptr& lease,
 }
 
 void
-AllocEngine::setLeaseRemainingLife(Lease& lease, const SubnetPtr& subnet) const {
+AllocEngine::setLeaseRemainingLife(const Lease4Ptr& lease,
+                                   const ClientContext4& ctx) const {
     // Sanity.
-    lease.remaining_valid_lft_ = 0;
+    lease->remaining_valid_lft_ = 0;
+    const Subnet4Ptr& subnet = ctx.subnet_;
     if (!subnet) {
         return;
     }
 
     // Always reuse infinite lifetime leases.
-    if (lease.valid_lft_ == Lease::INFINITY_LFT) {
-        lease.remaining_valid_lft_ = Lease::INFINITY_LFT;
+    if (lease->valid_lft_ == Lease::INFINITY_LFT) {
+        lease->remaining_valid_lft_ = Lease::INFINITY_LFT;
+        return;
     }
 
-    // Refuse time going backward.
-    if (lease.cltt_ > lease.current_cltt_) {
+    // Refuse time not going forward.
+    if (lease->cltt_ >= lease->current_cltt_) {
         return;
     }
-    uint32_t age = lease.current_cltt_ - lease.cltt_;
+
+    uint32_t age = lease->current_cltt_ - lease->cltt_;
     // Already expired.
-    if (age > lease.current_valid_lft_) {
+    if (age >= lease->current_valid_lft_) {
         return;
     }
 
@@ -4399,14 +4403,73 @@ AllocEngine::setLeaseRemainingLife(Lease& lease, const SubnetPtr& subnet) const
         if ((threshold <= 0.) || (threshold > 1.)) {
             return;
         }
-        max_age = lease.valid_lft_ * threshold;
+        max_age = lease->valid_lft_ * threshold;
         if (age > max_age) {
             return;
         }
     }
 
     // Seems to be reusable.
-    lease.remaining_valid_lft_ = lease.current_cltt_ - age;
+    lease->remaining_valid_lft_ = lease->current_valid_lft_ - age;
+}
+
+void
+AllocEngine::setLeaseRemainingLife(const Lease6Ptr& lease,
+                                   const ClientContext6& ctx) const {
+    // Sanity.
+    lease->remaining_valid_lft_ = 0;
+    const Subnet6Ptr& subnet = ctx.subnet_;
+    if (!subnet) {
+        return;
+    }
+
+    // Refuse time not going forward.
+    if (lease->cltt_ >= lease->current_cltt_) {
+        return;
+    }
+
+    uint32_t age = lease->current_cltt_ - lease->cltt_;
+    // Already expired.
+    if (age >= lease->current_valid_lft_) {
+        return;
+    }
+
+    // Try cache max age.
+    uint32_t max_age = 0;
+    if (!subnet->getCacheMaxAge().unspecified()) {
+        max_age = subnet->getCacheMaxAge().get();
+        if ((max_age == 0) || (age > max_age)) {
+            return;
+        }
+    }
+
+    // Try cache threshold.
+    if (!subnet->getCacheThreshold().unspecified()) {
+        double threshold = subnet->getCacheThreshold().get();
+        if ((threshold <= 0.) || (threshold > 1.)) {
+            return;
+        }
+        max_age = lease->valid_lft_ * threshold;
+        if (age > max_age) {
+            return;
+        }
+    }
+
+    // Seems to be reusable.
+    if ((lease->remaining_preferred_lft_ == Lease::INFINITY_LFT) ||
+        (lease->remaining_preferred_lft_ == 0)) {
+        // Keep these values.
+    } else if (lease->remaining_preferred_lft_ > age) {
+        lease->remaining_preferred_lft_ -= age;
+    } else {
+        // Can be a misconfiguration so stay safe...
+        return;
+    }
+    if (lease->current_valid_lft_ == Lease::INFINITY_LFT) {
+        lease->remaining_valid_lft_ = Lease::INFINITY_LFT;
+    } else {
+        lease->remaining_valid_lft_ = lease->current_valid_lft_ - age;
+    }
 }
 
 }  // namespace dhcp
diff --git a/src/lib/dhcpsrv/alloc_engine.h b/src/lib/dhcpsrv/alloc_engine.h
index de0046bcbe..6e1cdf903e 100644
--- a/src/lib/dhcpsrv/alloc_engine.h
+++ b/src/lib/dhcpsrv/alloc_engine.h
@@ -1858,9 +1858,31 @@ private:
     ///  - the lease is not updated in the lease database.
     ///  - the previous value of the lease can be returned to the client.
     ///
-    /// @param [in,out] lease The lease to be updated.
+    /// @param [in,out] lease A pointer to the lease to be updated.
     /// @param subnet A pointer to the lease subnet.
-    void setLeaseRemainingLife(Lease& lease, const SubnetPtr& subnet) const;
+    void setLeaseRemainingLife(const Lease4Ptr& lease,
+                               const ClientContext4& ctx) const;
+
+    /// @brief Try to reuse an already allocated lease.
+    ///
+    /// This function computes and sets when acceptable the remaining
+    /// valid lifetime of an already allocated lease.
+    /// This uses the cache-threshold and cache-max-age parameters.
+    ///
+    /// A not zero value for the remaining valid lifetime means the
+    /// lease can reuse i.e.:
+    ///  - the lease is not updated in the lease database.
+    ///  - the previous value of the lease can be returned to the client.
+    ///
+    /// @note: there is no current_preferred_lft_ field in the lease
+    /// so the remaining_preferred_lft_ is used too for this:
+    ///  - it must be set to the previous preferred lifetime before call.
+    ///  - after call it must be ignored if remaining valid lifetime is zero.
+    ///
+    /// @param [in,out] lease A pointer to the lease to be updated.
+    /// @param subnet A pointer to the lease subnet.
+    void setLeaseRemainingLife(const Lease6Ptr& lease,
+                               const ClientContext6& ctx) const;
 
 private:
 
diff --git a/src/lib/dhcpsrv/lease.cc b/src/lib/dhcpsrv/lease.cc
index 3e7157a06e..a05b78ee48 100644
--- a/src/lib/dhcpsrv/lease.cc
+++ b/src/lib/dhcpsrv/lease.cc
@@ -489,7 +489,7 @@ Lease6::Lease6(Lease::Type type, const isc::asiolink::IOAddress& addr,
                SubnetID subnet_id, const HWAddrPtr& hwaddr, uint8_t prefixlen)
     : Lease(addr, valid, subnet_id, 0/*cltt*/, false, false, "", hwaddr),
       type_(type), prefixlen_(prefixlen), iaid_(iaid), duid_(duid),
-      preferred_lft_(preferred) {
+      preferred_lft_(preferred), remaining_preferred_lft_(0) {
     if (!duid) {
         isc_throw(InvalidOperation, "DUID is mandatory for an IPv6 lease");
     }
@@ -506,7 +506,7 @@ Lease6::Lease6(Lease::Type type, const isc::asiolink::IOAddress& addr,
     : Lease(addr, valid, subnet_id, 0/*cltt*/,
             fqdn_fwd, fqdn_rev, hostname, hwaddr),
       type_(type), prefixlen_(prefixlen), iaid_(iaid), duid_(duid),
-      preferred_lft_(preferred) {
+      preferred_lft_(preferred), remaining_preferred_lft_(0) {
     if (!duid) {
         isc_throw(InvalidOperation, "DUID is mandatory for an IPv6 lease");
     }
@@ -518,7 +518,7 @@ Lease6::Lease6(Lease::Type type, const isc::asiolink::IOAddress& addr,
 Lease6::Lease6()
     : Lease(isc::asiolink::IOAddress("::"), 0, 0, 0, false, false, "",
             HWAddrPtr()), type_(TYPE_NA), prefixlen_(0), iaid_(0),
-            duid_(DuidPtr()), preferred_lft_(0) {
+            duid_(DuidPtr()), preferred_lft_(0), remaining_preferred_lft_(0) {
 }
 
 std::string
@@ -621,6 +621,7 @@ Lease6::operator==(const Lease6& other) const {
             prefixlen_ == other.prefixlen_ &&
             iaid_ == other.iaid_ &&
             preferred_lft_ == other.preferred_lft_ &&
+            remaining_preferred_lft_ == other.remaining_preferred_lft_ &&
             valid_lft_ == other.valid_lft_ &&
             current_valid_lft_ == other.current_valid_lft_ &&
             remaining_valid_lft_ == other.remaining_valid_lft_ &&
diff --git a/src/lib/dhcpsrv/lease.h b/src/lib/dhcpsrv/lease.h
index 48d81ca428..7def545356 100644
--- a/src/lib/dhcpsrv/lease.h
+++ b/src/lib/dhcpsrv/lease.h
@@ -521,12 +521,18 @@ struct Lease6 : public Lease {
     /// @brief Client identifier
     DuidPtr duid_;
 
-    /// @brief preferred lifetime
+    /// @brief Preferred lifetime
     ///
     /// This parameter specifies the preferred lifetime since the lease was
     /// assigned or renewed (cltt), expressed in seconds.
     uint32_t preferred_lft_;
 
+    /// @brief Remaining preferred lifetime
+    ///
+    /// Expressed as number of seconds since current time, also
+    /// preferred lifetime - age where age is old cltt - new cltt.
+    uint32_t remaining_preferred_lft_;
+
     /// @todo: Add DHCPv6 failover related fields here
 
     /// @brief Constructor