Commit fcedc148 authored by Marcin Siodelski's avatar Marcin Siodelski

[3035] Implemented DHCPv4 srv function to process an FQDN option.

parent 847cada3
......@@ -76,6 +76,34 @@ Dhcp4Hooks Hooks;
namespace isc {
namespace dhcp {
namespace {
// The following constants describe server's behavior with respect to the
// DHCPv4 Client FQDN Option sent by a client. They will be removed
// when DDNS parameters for DHCPv4 are implemented with the ticket #3033.
// Should server always include the FQDN option in its response, regardless
// if it has been requested in Parameter Request List Option (Disabled).
const bool FQDN_ALWAYS_INCLUDE = false;
// Enable A RR update delegation to the client (Disabled).
const bool FQDN_ALLOW_CLIENT_UPDATE = false;
// Globally enable updates (Enabled).
const bool FQDN_ENABLE_UPDATE = true;
// The partial name generated for the client if empty name has been
// supplied.
const char* FQDN_GENERATED_PARTIAL_NAME = "myhost";
// Do update, even if client requested no updates with N flag (Disabled).
const bool FQDN_OVERRIDE_NO_UPDATE = false;
// Server performs an update when client requested delegation (Enabled).
// The fully qualified domain-name suffix if partial name provided by
// a client.
const char* FQDN_PARTIAL_SUFFIX = "";
// Should server replace the domain-name supplied by the client (Disabled).
const bool FQDN_REPLACE_CLIENT_NAME = false;
/// @brief file name of a server-id file
/// Server must store its server identifier in persistent storage that must not
......@@ -695,6 +723,74 @@ Dhcpv4Srv::processClientFqdnOption(const Option4ClientFqdnPtr& fqdn,
fqdn_resp->setFlag(Option4ClientFqdn::FLAG_O, 0);
fqdn_resp->setFlag(Option4ClientFqdn::FLAG_N, 0);
// Conditions when N flag has to be set to indicate that server will not
// perform DNS updates:
// 1. Updates are globally disabled,
// 2. Client requested no update and server respects it,
// 3. Client requested that the foward DNS update is delegated to the client
// but server neither respects requests for forward update delegation nor
// it is configured to send update on its own when client requested
// delegation.
(fqdn->getFlag(Option4ClientFqdn::FLAG_N) &&
(!fqdn->getFlag(Option4ClientFqdn::FLAG_S) &&
fqdn_resp->setFlag(Option4ClientFqdn::FLAG_N, true);
// Conditions when S flag is set to indicate that server will perform DNS
// update on its own:
// 1. Client requested that server performs DNS update and DNS updates are
// globally enabled.
// 2. Client requested that server delegates forward update to the client
// but server doesn't respect requests for delegation and it is
// configured to perform an update on its own when client requested the
// delegation.
} else if (fqdn->getFlag(Option4ClientFqdn::FLAG_S) ||
(!fqdn->getFlag(Option4ClientFqdn::FLAG_S) &&
fqdn_resp->setFlag(Option4ClientFqdn::FLAG_S, true);
// Server MUST set the O flag if it has overriden the client's setting
// of S flag.
if (fqdn->getFlag(Option4ClientFqdn::FLAG_S) !=
fqdn_resp->getFlag(Option4ClientFqdn::FLAG_S)) {
fqdn_resp->setFlag(Option4ClientFqdn::FLAG_O, true);
// If client suppled partial or empty domain-name, server should generate
// one.
if (fqdn->getDomainNameType() == Option4ClientFqdn::PARTIAL) {
std::ostringstream name;
if (fqdn->getDomainName().empty()) {
} else {
name << fqdn->getDomainName();
name << "." << FQDN_PARTIAL_SUFFIX;
fqdn_resp->setDomainName(name.str(), Option4ClientFqdn::FULL);
// Server may be configured to replace a name supplied by a client, even if
// client supplied fully qualified domain-name.
std::ostringstream name;
fqdn_resp->setDomainName(name.str(), Option4ClientFqdn::FULL);
// Add FQDN option to the response message. Note that, there may be some
// cases when server may choose not to include the FQDN option in a
// response to a client. In such cases, the FQDN should be removed from the
// outgoing message. In theory we could cease to include the FQDN option
// in this function until it is confirmed that it should be included.
// However, we include it here for simplicity. Functions used to acquire
// lease for a client will scan the response message for FQDN and if it
// is found they will take necessary actions to store the FQDN information
// in the lease database as well as to generate NameChangeRequests to DNS.
// If we don't store the option in the reponse message, we will have to
// propagate it in the different way to the functions which acquire the
// lease. This would require modifications to the API of this class.
......@@ -174,13 +174,25 @@ TEST_F(FqdnDhcpv4SrvTest, serverUpdateForwardNoName) {
// Test server's response when client requests no DNS update.
TEST_F(FqdnDhcpv4SrvTest, noUpdate) {
Pkt4Ptr query = generatePktWithFqdn(DHCPREQUEST,
Option4ClientFqdn::FLAG_E |
testProcessFqdn(query, Option4ClientFqdn::FLAG_E | Option4ClientFqdn::FLAG_N,
// Test that server does not accept delegation of the forward DNS update
// to a client.
TEST_F(FqdnDhcpv4SrvTest, clientUpdateNotAllowed) {
Pkt4Ptr query = generatePktWithFqdn(DHCPREQUEST,
testProcessFqdn(query, Option4ClientFqdn::FLAG_E |
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