addressed issues in review

src/lib/dhcp_ddns/ncr_msg.cc

@@ -105,6 +105,19 @@ D2Dhcid::fromClientId(const std::vector<uint8_t>& clientid_data,
     // | 255 | i1 | i2 | i3 | i4 | d1 | d2 |...
     // +-----+----+----+----+----+----+----+---
     if (!clientid_data.empty() && clientid_data[0] == 255) {
+        if (clientid_data.size() <= 5) {
+            isc_throw(isc::dhcp_ddns::DhcidRdataComputeError,
+                      "unable to compute DHCID from client identifier, embedded DUID "
+                      "length of: " << clientid_data.size() << ", is too short");
+        }
+        // RFC3315 states that the DUID is a type code of 2 octets followed 
+        // by no more then 128 octets. So add the 5 from above and make sure
+        // the length is not too long.
+        if (clientid_data.size() > 135) {
+            isc_throw(isc::dhcp_ddns::DhcidRdataComputeError,
+                      "unable to compute DHCID from client identifier, embedded DUID "
+                      "length of: " << clientid_data.size() << ", is too long");
+        }
         std::vector<uint8_t>::const_iterator start = clientid_data.begin() + 5;
         std::vector<uint8_t>::const_iterator end = clientid_data.end();
         std::vector<uint8_t> duid(start, end);

src/lib/dhcp_ddns/tests/ncr_unittests.cc

@@ -476,13 +476,13 @@ TEST_F(DhcidTest, fromClientIdDUID) {
     // Make sure that the DHCID is valid.
     EXPECT_EQ(dhcid_ref, dhcid.toStr());
 
-    // Make sure that the empty FQDN is not accepted.
-    std::vector<uint8_t> empty_wire_fqdn;
-    EXPECT_THROW(dhcid.fromClientId(clientid, empty_wire_fqdn),
+    // Make sure that a too long client identifier is not accepted.
+    clientid.resize(136);
+    EXPECT_THROW(dhcid.fromClientId(clientid, wire_fqdn_),
                  isc::dhcp_ddns::DhcidRdataComputeError);
 
-    // Make sure that the empty client identifier is not accepted.
-    clientid.clear();
+    // Make sure that a too short client identifier is not accepted.
+    clientid.resize(5);
     EXPECT_THROW(dhcid.fromClientId(clientid, wire_fqdn_),
                  isc::dhcp_ddns::DhcidRdataComputeError);