diff -up dhcp-4.2.4b1/server/dhcpv6.c.UseMulticast dhcp-4.2.4b1/server/dhcpv6.c

--- dhcp-4.2.4b1/server/dhcpv6.c.UseMulticast	2012-04-11 00:14:04.000000000 +0200

+++ dhcp-4.2.4b1/server/dhcpv6.c	2012-04-16 19:21:43.575923732 +0200

@@ -346,6 +346,48 @@ generate_new_server_duid(void) {

 }

 /*

+ * Is the D6O_UNICAST option defined in dhcpd.conf ?

+ */

+static isc_boolean_t unicast_option_defined;

+

+/*

+ * Did we already search dhcpd.conf for D6O_UNICAST option ?

+ * We need to store it here to not parse dhcpd.conf repeatedly.

+ */

+static isc_boolean_t unicast_option_parsed = ISC_FALSE;

+

+

+/*

+ * Is the D6O_UNICAST option defined in dhcpd.conf ?

+ */

+isc_boolean_t

+is_unicast_option_defined(void) {

+	struct option_state *opt_state;

+	struct option_cache *oc;

+

+	/*

+	 * If we are looking for the unicast option for the first time

+	 */

+	if (unicast_option_parsed == ISC_FALSE) {

+		unicast_option_parsed = ISC_TRUE;

+		opt_state = NULL;

+		if (!option_state_allocate(&opt_state, MDL)) {

+			log_fatal("No memory for option state.");

+		}

+

+		execute_statements_in_scope(NULL, NULL, NULL, NULL, NULL,

+				opt_state, &global_scope, root_group, NULL);

+

+		oc = lookup_option(&dhcpv6_universe, opt_state, D6O_UNICAST);

+		unicast_option_defined = (oc != NULL);

+

+		option_state_dereference(&opt_state, MDL);

+	}

+

+	return (unicast_option_defined);

+}

+

+/*

  * Get the client identifier from the packet.

  */

 isc_result_t

@@ -1404,6 +1446,56 @@ lease_to_client(struct data_string *repl

 						    reply.shared->group);

 	}

+	/* reject unicast message, unless we set unicast option */

+	if ((packet->unicast == ISC_TRUE) && !is_unicast_option_defined())

+	/*

+	 * RFC3315 section 18.2.1 (Request):

+	 *

+	 * When the server receives a Request message via unicast from a client

+	 * to which the server has not sent a unicast option, the server

+	 * discards the Request message and responds with a Reply message

+	 * containing a Status Code option with the value UseMulticast, a Server

+	 * Identifier option containing the server's DUID, the Client Identifier

+	 * option from the client message, and no other options.

+	 *

+	 * Section 18.2.3 (Renew):

+	 *

+	 * When the server receives a Renew message via unicast from a client to

+	 * which the server has not sent a unicast option, the server discards

+	 * the Renew message and responds with a Reply message containing a

+	 * Status Code option with the value UseMulticast, a Server Identifier

+	 * option containing the server's DUID, the Client Identifier option

+	 * from the client message, and no other options.

+	 */

+	{

+		/* Set the UseMulticast status code. */

+		if (!set_status_code(STATUS_UseMulticast,

+					"Unicast not allowed by server.",

+					reply.opt_state)) {

+			log_error("lease_to_client: Unable to set "

+					"UseMulticast status code.");

+			goto exit;

+		}

+

+		/* Rewind the cursor to the start. */

+		reply.cursor = REPLY_OPTIONS_INDEX;

+

+		/*

+		 * Produce an reply that includes only:

+		 *

+		 * Status code.

+		 * Server DUID.

+		 * Client DUID.

+		 */

+		reply.cursor += store_options6((char *)reply.buf.data +

+					reply.cursor,

+					sizeof(reply.buf) -

+					reply.cursor,

+					reply.opt_state, reply.packet,

+					required_opts_NAA,

+					NULL);

+	}

+

 	/*

 	 * RFC3315 section 17.2.2 (Solicit):

 	 *

@@ -1429,8 +1521,8 @@ lease_to_client(struct data_string *repl

 	 * Sends a Renew/Rebind if the IA is not in the Reply message.

 	 */

 #if defined (RFC3315_PRE_ERRATA_2010_08)

-	if (no_resources_avail && (reply.ia_count != 0) &&

-	    (reply.packet->dhcpv6_msg_type == DHCPV6_SOLICIT))

+	else if (no_resources_avail && (reply.ia_count != 0) &&

+		 (reply.packet->dhcpv6_msg_type == DHCPV6_SOLICIT))

 	{

 		/* Set the NoAddrsAvail status code. */

 		if (!set_status_code(STATUS_NoAddrsAvail,

@@ -1477,6 +1569,7 @@ lease_to_client(struct data_string *repl

 	 * Having stored the client's IA's, store any options that

 	 * will fit in the remaining space.

 	 */

+	else 

 	reply.cursor += store_options6((char *)reply.buf.data + reply.cursor,

 				       sizeof(reply.buf) - reply.cursor,

 				       reply.opt_state, reply.packet,

@@ -4126,7 +4219,6 @@ dhcpv6_solicit(struct data_string *reply

  * Very similar to Solicit handling, except the server DUID is required.

  */

-/* TODO: reject unicast messages, unless we set unicast option */

 static void

 dhcpv6_request(struct data_string *reply_ret, struct packet *packet) {

 	struct data_string client_id;

@@ -4456,7 +4548,6 @@ exit:

  * except for the error code of when addresses don't match.

  */

-/* TODO: reject unicast messages, unless we set unicast option */

 static void

 dhcpv6_renew(struct data_string *reply, struct packet *packet) {

 	struct data_string client_id;

@@ -4700,18 +4791,60 @@ iterate_over_ia_na(struct data_string *r

 		goto exit;

 	}

-	snprintf(status_msg, sizeof(status_msg), "%s received.", packet_type);

-	if (!set_status_code(STATUS_Success, status_msg, opt_state)) {

-		goto exit;

-	}

+	/* reject unicast message, unless we set unicast option */

+	if ((packet->unicast == ISC_TRUE) && !is_unicast_option_defined()) {

+		/*

+		 * RFC3315 section 18.2.6 (Release):

+		 *

+		 * When the server receives a Release message via unicast from a client

+		 * to which the server has not sent a unicast option, the server

+		 * discards the Release message and responds with a Reply message

+		 * containing a Status Code option with value UseMulticast, a Server

+		 * Identifier option containing the server's DUID, the Client Identifier

+		 * option from the client message, and no other options.

+		 *

+		 * Section 18.2.7 (Decline):

+		 *

+		 * When the server receives a Decline message via unicast from a client

+		 * to which the server has not sent a unicast option, the server

+		 * discards the Decline message and responds with a Reply message

+		 * containing a Status Code option with the value UseMulticast, a Server

+		 * Identifier option containing the server's DUID, the Client Identifier

+		 * option from the client message, and no other options.

+		 */

+		snprintf(status_msg, sizeof(status_msg),

+				 "%s received unicast.", packet_type);

+		if (!set_status_code(STATUS_UseMulticast, status_msg, opt_state)) {

+			goto exit;

+		}

-	/* 

-	 * Add our options that are not associated with any IA_NA or IA_TA. 

-	 */

-	reply_ofs += store_options6(reply_data+reply_ofs,

-				    sizeof(reply_data)-reply_ofs, 

+		/*

+		 * Produce an reply that includes only:

+		 *

+		 * Status code.

+		 * Server DUID.

+		 * Client DUID.

+		 */

+		reply_ofs += store_options6(reply_data+reply_ofs,

+				    sizeof(reply_data)-reply_ofs,

 				    opt_state, packet,

-				    required_opts, NULL);

+				    required_opts_NAA, NULL);

+

+		goto return_reply;

+	} else {

+		snprintf(status_msg, sizeof(status_msg), "%s received.", packet_type);

+		if (!set_status_code(STATUS_Success, status_msg, opt_state)) {

+			goto exit;

+		}

+

+		/*

+		 * Add our options that are not associated with any IA_NA or IA_TA.

+		 */

+		reply_ofs += store_options6(reply_data+reply_ofs,

+					    sizeof(reply_data)-reply_ofs,

+					    opt_state, packet,

+					    required_opts, NULL);

+	}

 	/*

 	 * Loop through the IA_NA reported by the client, and deal with

@@ -4849,6 +4982,7 @@ iterate_over_ia_na(struct data_string *r

 	/* 

 	 * Return our reply to the caller.

 	 */

+return_reply:

 	reply_ret->len = reply_ofs;

 	reply_ret->buffer = NULL;

 	if (!buffer_allocate(&reply_ret->buffer, reply_ofs, MDL)) {

@@ -4894,7 +5028,6 @@ exit:

  * we still need to be aware of this possibility.

  */

-/* TODO: reject unicast messages, unless we set unicast option */

 /* TODO: IA_TA */

 static void

 dhcpv6_decline(struct data_string *reply, struct packet *packet) {

@@ -5364,7 +5497,6 @@ exit:

  * Release means a client is done with the leases.

  */

-/* TODO: reject unicast messages, unless we set unicast option */

 static void

 dhcpv6_release(struct data_string *reply, struct packet *packet) {

 	struct data_string client_id;