[2719] Emergency fix for renew when there are no subnets configured.

ChangeLog

@@ -1,3 +1,8 @@
+5XX.	[bug]		tmark, tomek
+	b10-dhcp6: Server aborts operation when receiving renew and there
+	are no IPv6 subnets configured.
+	(Trac 2719, git TBD)
+
 573.	[bug]		stephen
 	Fixed problem whereby the DHCP server crashed if it ran out of
 	addresses.  Such a condition now causes a packet to be returned

src/bin/dhcp6/dhcp6_messages.mes

@@ -222,6 +222,16 @@ as a hint for possible requested address.
 % DHCP6_QUERY_DATA received packet length %1, data length %2, data is %3
 A debug message listing the data received from the client or relay.
 
+% DHCP6_RENEW_UNKNOWN_SUBNET RENEW message received from client on unknown subnet (duid=%1, iaid=%2)
+A warning message indicating that a client is attempting to renew his lease,
+but the server does not have any information about the subnet this client belongs
+to. This may mean that faulty the mobile client changed its location and is trying to
+renew its old address (client is supposed to send confirm, not rewew in such cases,
+according to RFC3315) or the server configuration has changed and information about
+existing subnet was removed. Note that in a sense this is worse case of DHCP6_UNKNOWN_RENEW,
+as not only the lease is unknown, but also the subnet is. Depending on the reasons
+of this condition, it may or may not correct on its own.
+
 % DHCP6_REQUIRED_OPTIONS_CHECK_FAIL %1 message received from %2 failed the following check: %3
 This message indicates that received DHCPv6 packet is invalid.  This may be due
 to a number of reasons, e.g. the mandatory client-id option is missing,

src/bin/dhcp6/dhcp6_srv.cc

@@ -714,6 +714,21 @@ Dhcpv6Srv::assignIA_NA(const Subnet6Ptr& subnet, const DuidPtr& duid,
 OptionPtr
 Dhcpv6Srv::renewIA_NA(const Subnet6Ptr& subnet, const DuidPtr& duid,
                       Pkt6Ptr /* question */, boost::shared_ptr<Option6IA> ia) {
+    if (!subnet) {
+        // There's no subnet select for this client. There's nothing to renew.
+        boost::shared_ptr<Option6IA> ia_rsp(new Option6IA(D6O_IA_NA, ia->getIAID()));
+
+        // Insert status code NoAddrsAvail.
+        ia_rsp->addOption(createStatusCode(STATUS_NoBinding,
+                          "Sorry, no known leases for this duid/iaid."));
+
+        LOG_DEBUG(dhcp6_logger, DBG_DHCP6_DETAIL, DHCP6_RENEW_UNKNOWN_SUBNET)
+            .arg(duid->toText())
+            .arg(ia->getIAID());
+
+        return (ia_rsp);
+    }
+
     Lease6Ptr lease = LeaseMgrFactory::instance().getLease6(*duid, ia->getIAID(),
                                                             subnet->getID());
 
@@ -777,7 +792,9 @@ Dhcpv6Srv::renewLeases(const Pkt6Ptr& renew, Pkt6Ptr& reply) {
 
         // perhaps this should be logged on some higher level? This is most likely
         // configuration bug.
-        LOG_ERROR(dhcp6_logger, DHCP6_SUBNET_SELECTION_FAILED);
+        LOG_ERROR(dhcp6_logger, DHCP6_SUBNET_SELECTION_FAILED)
+            .arg(renew->getRemoteAddr().toText())
+            .arg(renew->getName());
     } else {
         LOG_DEBUG(dhcp6_logger, DBG_DHCP6_DETAIL_DATA, DHCP6_SUBNET_SELECTED)
             .arg(subnet->toText());