[master] dhcpd (-6) now supports update-static-leases

Merges in rt34097.

RELNOTES

@@ -284,6 +284,18 @@ dhcp-users@lists.isc.org.
 - Corrected some minor coverity issues: CID 1426059, 1426058, and 1426057.
   [ISC-Bugs #46836]
 
+- The server (-6) now honors the parameter, update-static-leases, for static
+  (fixed-address6) DHCPv6 leases.  It is worth noting that because stateful
+  data is not retained by the server for static leases, each time a client
+  requests or renews a static lease, the server will perform DDNS updates for
+  it. This may have significant performance implications for environments
+  with many clients that request or renew static leases often. Similarly,
+  the DNS entries will not be removed by server when a client issues a RELEASE
+  nor if the lease is deleted from the configuration. In such cases the DNS
+  entries must be removed manually. This feature is disabled by default.
+  [ISC-Bugs #34097]
+  [ISC-Bugs #41054]
+
 			Changes since 4.3.6 (Bugs):
 
 - Corrected an issue where the server would return a client's previously

common/dns.c

@@ -594,9 +594,16 @@ ddns_cb_free(dhcp_ddns_cb_t *ddns_cb, const char *file, int line)
 	}
 
 	/* Should be freed by now, check just in case. */
-	if (ddns_cb->transaction != NULL)
+	if (ddns_cb->transaction != NULL) {
 		log_error("Impossible memory leak at %s:%d (attempt to free "
 			  "DDNS Control Block before transaction).", MDL);
+	}
+
+	/* Should be freed by now, check just in case. */
+	if (ddns_cb->fixed6_ia) {
+		log_error("Possible memory leak at %s:%d (attempt to free "
+			  "DDNS Control Block before fxed6_ia).", MDL);
+	}
 
 	dfree(ddns_cb, file, line);
 }

includes/dhcpd.h

@@ -1646,6 +1646,7 @@ struct iasubopt {
 
 	/* space for the on * executable statements */
 	struct on_star on_star;
+	int static_lease;
 };
 
 struct ia_xx {
@@ -1818,6 +1819,7 @@ typedef struct dhcp_ddns_cb {
 	dns_rdataclass_t dhcid_class;
 	dns_rdataclass_t other_dhcid_class;
 	char *lease_tag;
+	struct ia_xx *fixed6_ia;
 } dhcp_ddns_cb_t;
 
 extern struct ipv6_pool **pools;

server/ddns.c

@@ -57,6 +57,25 @@ static void copy_conflict_flags(u_int16_t *target, u_int16_t source);
 
 static void ddns_fwd_srv_add3(dhcp_ddns_cb_t *ddns_cb, isc_result_t eresult);
 
+/*
+ * ddns_cb_free() is part of common lib, while ia_* routines are known
+ * only in the server.  Use this wrapper instead of ddns_cb_free() directly.
+ */
+static void
+destroy_ddns_cb(struct dhcp_ddns_cb *ddns_cb, char* file, int line) {
+	if (!ddns_cb) {
+		return;
+	}
+
+        if (ddns_cb->fixed6_ia) {
+                ia_dereference(&ddns_cb->fixed6_ia, MDL);
+        }
+
+	ddns_cb_free(ddns_cb, file, line);
+
+}
+
+
 /* DN: No way of checking that there is enough space in a data_string's
    buffer.  Be certain to allocate enough!
    TL: This is why the expression evaluation code allocates a *new*
@@ -153,6 +172,13 @@ ddns_updates(struct packet *packet, struct lease *lease, struct lease *old,
 		scope = &(lease6->scope);
 		memcpy(ddns_cb->address.iabuf, lease6->addr.s6_addr, 16);
 		ddns_cb->address.len = 16;
+
+		if (lease6->static_lease) {
+			/* We add a reference to keep ia && iasubopt alive
+			* since static v6s are retained anywhere */
+			ia_reference(&ddns_cb->fixed6_ia, lease6->ia, MDL);
+			ddns_cb->flags |= DDNS_STATIC_LEASE;
+		}
 	}
 
 	memset (&d1, 0, sizeof(d1));
@@ -754,7 +780,7 @@ ddns_updates(struct packet *packet, struct lease *lease, struct lease *old,
 	 * Final cleanup.
 	 */
 	if (ddns_cb != NULL) {
-		ddns_cb_free(ddns_cb, MDL);
+		destroy_ddns_cb(ddns_cb, MDL);
 	}
 
 	data_string_forget(&d1, MDL);
@@ -1296,7 +1322,7 @@ ddns_ptr_add(dhcp_ddns_cb_t *ddns_cb,
 	}
 
 	ddns_update_lease_ptr(NULL, NULL, ddns_cb, NULL, MDL);
-	ddns_cb_free(ddns_cb, MDL);
+	destroy_ddns_cb(ddns_cb, MDL);
 	/*
 	 * A single DDNS operation may require several calls depending on
 	 * the current state as the prerequisites for the first message
@@ -1362,7 +1388,7 @@ ddns_ptr_remove(dhcp_ddns_cb_t *ddns_cb,
 
 	ddns_update_lease_ptr(NULL, NULL, ddns_cb, NULL, MDL);
 	ddns_fwd_srv_connector(NULL, NULL, NULL, ddns_cb->next_op, result);
-	ddns_cb_free(ddns_cb, MDL);
+	destroy_ddns_cb(ddns_cb, MDL);
 	return;
 }
 
@@ -1476,7 +1502,7 @@ ddns_fwd_srv_add2(dhcp_ddns_cb_t *ddns_cb,
 	}
 
 	ddns_update_lease_ptr(NULL, NULL, ddns_cb, NULL, MDL);
-	ddns_cb_free(ddns_cb, MDL);
+	destroy_ddns_cb(ddns_cb, MDL);
 	/*
 	 * A single DDNS operation may require several calls depending on
 	 * the current state as the prerequisites for the first message
@@ -1551,7 +1577,7 @@ ddns_fwd_srv_add1(dhcp_ddns_cb_t *ddns_cb,
 	}
 
 	ddns_update_lease_ptr(NULL, NULL, ddns_cb, NULL, MDL);
-	ddns_cb_free(ddns_cb, MDL);
+	destroy_ddns_cb(ddns_cb, MDL);
 	/*
 	 * A single DDNS operation may require several calls depending on
 	 * the current state as the prerequisites for the first message
@@ -1636,7 +1662,7 @@ ddns_fwd_srv_add3(dhcp_ddns_cb_t *ddns_cb,
 	}
 
 	ddns_update_lease_ptr(NULL, NULL, ddns_cb, NULL, MDL);
-	ddns_cb_free(ddns_cb, MDL);
+	destroy_ddns_cb(ddns_cb, MDL);
 	/*
 	 * A single DDNS operation may require several calls depending on
 	 * the current state as the prerequisites for the first message
@@ -1694,7 +1720,7 @@ ddns_fwd_srv_connector(struct lease          *lease,
 	if (result == ISC_R_SUCCESS) {
 		ddns_update_lease_ptr(lease, lease6, ddns_cb, ddns_cb, MDL);
 	} else {
-		ddns_cb_free(ddns_cb, MDL);
+		destroy_ddns_cb(ddns_cb, MDL);
 	}
 
 	return;
@@ -1762,7 +1788,7 @@ ddns_fwd_srv_rem2(dhcp_ddns_cb_t *ddns_cb,
 
 	ddns_update_lease_ptr(NULL, NULL, ddns_cb, NULL, MDL);
 	ddns_fwd_srv_connector(NULL, NULL, NULL, ddns_cb->next_op, eresult);
-	ddns_cb_free(ddns_cb, MDL);
+	destroy_ddns_cb(ddns_cb, MDL);
 	return;
 }
 
@@ -1866,7 +1892,7 @@ ddns_fwd_srv_rem1(dhcp_ddns_cb_t *ddns_cb,
 
 	ddns_update_lease_ptr(NULL, NULL, ddns_cb, NULL, MDL);
 	ddns_fwd_srv_connector(NULL, NULL, NULL, ddns_cb->next_op, eresult);
-	ddns_cb_free(ddns_cb, MDL);
+	destroy_ddns_cb(ddns_cb, MDL);
 }
 
 /*%<
@@ -1952,7 +1978,7 @@ ddns_removals(struct lease    *lease,
 			} else {
 				/* Remvoval, check and remove updates */
 				if (ddns_cb->next_op != NULL) {
-					ddns_cb_free(ddns_cb->next_op, MDL);
+					destroy_ddns_cb(ddns_cb->next_op, MDL);
 					ddns_cb->next_op = NULL;
 				}
 #if defined (DEBUG_DNS_UPDATES)
@@ -1980,7 +2006,7 @@ ddns_removals(struct lease    *lease,
 			} else {
 				/* Remvoval, check and remove updates */
 				if (ddns_cb->next_op != NULL) {
-					ddns_cb_free(ddns_cb->next_op, MDL);
+					destroy_ddns_cb(ddns_cb->next_op, MDL);
 					ddns_cb->next_op = NULL;
 				}
 #if defined (DEBUG_DNS_UPDATES)
@@ -2191,7 +2217,7 @@ ddns_removals(struct lease    *lease,
 	 */
 	ddns_fwd_srv_connector(lease, lease6, scope, add_ddns_cb, execute_add);
 	if (ddns_cb != NULL)
-		ddns_cb_free(ddns_cb, MDL);
+		destroy_ddns_cb(ddns_cb, MDL);
 
 	return (result);
 }

server/dhcpd.conf.5

@@ -3379,13 +3379,15 @@ statement
 .PP
 The \fIupdate-static-leases\fR flag, if enabled, causes the DHCP
 server to do DNS updates for clients even if those clients are being
-assigned their IP address using a \fIfixed-address\fR statement - that
-is, the client is being given a static assignment.  It is not
-recommended because the DHCP server has no way to tell that the update
-has been done, and therefore will not delete the record when it is not
-in use.  Also, the server must attempt the update each time the
-client renews its lease, which could have a significant performance
-impact in environments that place heavy demands on the DHCP server.
+assigned their IP address using a \fIfixed-address\fR or
+\fIfixed-address6\fR statement - that is, the client is being given a
+static assignment.  It is not recommended because the DHCP server has
+no way to tell that the update has been done, and therefore will not
+delete the record when it is not in use.  Also, the server must attempt
+the update each time the client renews its lease, which could have a
+significant performance impact in environments that place heavy demands
+on the DHCP server.  This feature is supported for both DHCPv4 and DHCPv6,
+and update modes standard or interim. It is disabled by default.
 .RE
 .PP
 The

server/dhcpv6.c

@@ -185,6 +185,10 @@ static void shorten_lifetimes(struct reply_state *reply, struct iasubopt *lease,
 static void write_to_packet(struct reply_state *reply, unsigned ia_cursor);
 static const char *iasubopt_plen_str(struct iasubopt *lease);
 
+#ifdef NSUPDATE
+static void ddns_update_static6(struct reply_state* reply);
+#endif
+
 #ifdef DHCP4o6
 /*
  * \brief Omapi I/O handler
@@ -2227,7 +2231,10 @@ reply_process_ia_na(struct reply_state *reply, struct option_cache *ia) {
 
 		/* Write the lease out in wire-format to the outbound buffer */
 		write_to_packet(reply, ia_cursor);
-
+#ifdef NSUPDATE
+		/* Performs DDNS updates if we're configured to do them */
+		ddns_update_static6(reply);
+#endif
 		if ((reply->buf.reply.msg_type == DHCPV6_REPLY) &&
 		    (reply->on_star.on_commit != NULL)) {
 			execute_statements(NULL, reply->packet, NULL, NULL,
@@ -8448,4 +8455,66 @@ const char *iasubopt_plen_str(struct iasubopt *lease) {
 	return (prefix_buf);
 }
 
+#ifdef NSUPDATE
+/*
+ * Initiates DDNS updates for static v6 leases if configured to do so.
+ *
+ * The function, which must be called after the IA has been written to the
+ * packet, adds an iasubopt to the IA for static lease.  This is done so we
+ * have an iasubopt to pass into ddns_updates().  A reference to the IA is
+ * added to the DDNS control block to ensure it and it's iasubopt remain in
+ * scope until the update is complete.
+ *
+ */
+void ddns_update_static6(struct reply_state* reply) {
+	struct iasubopt *iasub = NULL;
+	struct binding_scope *scope = NULL;
+	struct option_cache *oc = NULL;
+
+	oc = lookup_option(&server_universe, reply->opt_state, SV_DDNS_UPDATES);
+	if ((oc != NULL) &&
+		(evaluate_boolean_option_cache(NULL, reply->packet, NULL, NULL,
+					       reply->packet->options,
+                                               reply->opt_state, NULL,
+                                               oc, MDL) == 0)) {
+		return;
+	}
+
+	oc = lookup_option(&server_universe, reply->opt_state,
+			   SV_UPDATE_STATIC_LEASES);
+	if ((oc == NULL) ||
+		(evaluate_boolean_option_cache(NULL, reply->packet,
+						     NULL, NULL,
+						     reply->packet->options,
+						     reply->opt_state, NULL,
+						     oc, MDL) == 0)) {
+		return;
+	}
+
+	if (iasubopt_allocate(&iasub, MDL) != ISC_R_SUCCESS) {
+		log_fatal("No memory for iasubopt.");
+	}
+
+	if (ia_add_iasubopt(reply->ia, iasub, MDL) != ISC_R_SUCCESS) {
+		log_fatal("Could not add iasubopt.");
+	}
+
+	ia_reference(&iasub->ia, reply->ia, MDL);
+
+	memcpy(iasub->addr.s6_addr, reply->fixed.data, 16);
+	iasub->plen = 0;
+	iasub->prefer =  MAX_TIME;
+	iasub->valid =  MAX_TIME;
+	iasub->static_lease = 1;
+
+	if (!binding_scope_allocate(&scope, MDL)) {
+		log_fatal("Out of memory for binding scope.");
+	}
+
+	binding_scope_reference(&iasub->scope, scope, MDL);
+
+	ddns_updates(reply->packet, NULL, NULL, iasub, NULL, reply->opt_state);
+}
+#endif /* NSUPDATE */
+
 #endif /* DHCPv6 */