path: root/common/dns.c

/* dns.c

   Domain Name Service subroutines. */

/*
 * Copyright (c) 2009-2012 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 2004-2007 by Internet Systems Consortium, Inc. ("ISC")
 * Copyright (c) 2001-2003 by Internet Software Consortium
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS.  IN NO EVENT SHALL ISC BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
 * OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 *   Internet Systems Consortium, Inc.
 *   950 Charter Street
 *   Redwood City, CA 94063
 *   <info@isc.org>
 *   https://www.isc.org/
 *
 * The original software was written for Internet Systems Consortium
 * by Ted Lemon it has since been extensively modified to use the
 * asynchronous DNS routines.
 */

#include "dhcpd.h"
#include "arpa/nameser.h"
#include <isc/md5.h>

#include <dns/result.h>

/*
 * This file contains code to connect the DHCP code to the libdns modules.
 * As part of that function it maintains a database of zone cuts that can
 * be used to figure out which server should be contacted to update any
 * given domain name.  Included in the zone information may be a pointer
 * to a key in which case that key is used for the update.  If no zone
 * is found then the DNS code determines the zone on its own.
 *
 * The way this works is that you define the domain name to which an
 * SOA corresponds, and the addresses of some primaries for that domain name:
 *
 *	zone FOO.COM {
 *	  primary 10.0.17.1;
 *	  secondary 10.0.22.1, 10.0.23.1;
 *	  key "FOO.COM Key";
 * 	}
 *
 * If an update is requested for GAZANGA.TOPANGA.FOO.COM, then the name
 * server looks in its database for a zone record for "GAZANGA.TOPANGA.FOO.COM",
 * doesn't find it, looks for one for "TOPANGA.FOO.COM", doesn't find *that*,
 * looks for "FOO.COM", finds it. So it
 * attempts the update to the primary for FOO.COM.   If that times out, it
 * tries the secondaries.   You can list multiple primaries if you have some
 * kind of magic name server that supports that.   You shouldn't list
 * secondaries that don't know how to forward updates (e.g., BIND 8 doesn't
 * support update forwarding, AFAIK).   If no TSIG key is listed, the update
 * is attempted without TSIG.
 *
 * You can also include IPv6 addresses via the primary6 and secondary6
 * options.  The search order for the addresses is primary, primary6,
 * secondary and lastly secondary6, with a limit on the number of 
 * addresses used.  Currently this limit is 3.
 *
 * The DHCP server tries to find an existing zone for any given name by
 * trying to look up a local zone structure for each domain containing
 * that name, all the way up to '.'.   If it finds one cached, it tries
 * to use that one to do the update.   That's why it tries to update
 * "FOO.COM" above, even though theoretically it should try GAZANGA...
 * and TOPANGA... first.
 *
 * If the update fails with a predefined zone the zone is marked as bad
 * and another search of the predefined zones is done.  If no predefined
 * zone is found finding a zone is left to the DNS module via examination
 * of SOA records.  If the DNS module finds a zone it may cache the zone
 * but the zone won't be cached here.
 *
 * TSIG updates are not performed on zones found by the DNS module - if
 * you want TSIG updates you _must_ write a zone definition linking the
 * key to the zone.   In cases where you know for sure what the key is
 * but do not want to hardcode the IP addresses of the primary or
 * secondaries, a zone declaration can be made that doesn't include any
 * primary or secondary declarations.   When the DHCP server encounters
 * this while hunting up a matching zone for a name, it looks up the SOA,
 * fills in the IP addresses, and uses that record for the update.
 * If the SOA lookup returns NXRRSET, a warning is printed and the zone is
 * discarded, TSIG key and all.   The search for the zone then continues 
 * as if the zone record hadn't been found.   Zones without IP addresses 
 * don't match when initially hunting for a zone to update.
 *
 * When an update is attempted and no predefined zone is found
 * that matches any enclosing domain of the domain being updated, the DHCP
 * server goes through the same process that is done when the update to a
 * predefined zone fails - starting with the most specific domain
 * name (GAZANGA.TOPANGA.FOO.COM) and moving to the least specific (the root),
 * it tries to look up an SOA record.
 *
 * TSIG keys are defined like this:
 *
 *	key "FOO.COM Key" {
 *		algorithm HMAC-MD5.SIG-ALG.REG.INT;
 *		secret <Base64>;
 *	}
 *
 * <Base64> is a number expressed in base64 that represents the key.
 * It's also permissible to use a quoted string here - this will be
 * translated as the ASCII bytes making up the string, and will not
 * include any NUL termination.  The key name can be any text string,
 * and the key type must be one of the key types defined in the draft
 * or by the IANA.  Currently only the HMAC-MD5... key type is
 * supported.
 *
 * The DDNS processing has been split into two areas.  One is the
 * control code that determines what should be done.  That code is found
 * in the client or server directories.  The other is the common code
 * that performs functions such as properly formatting the arguments.
 * That code is found in this file.  The basic processing flow for a
 * DDNS update is:
 * In the client or server code determine what needs to be done and
 * collect the necesary information then pass it to a function from
 * this file.
 * In this code lookup the zone and extract the zone and key information
 * (if available) and prepare the arguments for the DNS module.
 * When the DNS module completes its work (times out or gets a reply)
 * it will trigger another function here which does generic processing
 * and then passes control back to the code from the server or client.
 * The server or client code then determines the next step which may
 * result in another call to this module in which case the process repeats.
 */

dns_zone_hash_t *dns_zone_hash;

/*
 * DHCP dns structures
 * Normally the relationship between these structures isn't one to one
 * but in the DHCP case it (mostly) is.  To make the allocations, frees,
 * and passing of the memory easier we make a single structure with all
 * the pieces.
 *
 * The maximum size of the data buffer should be large enough for any
 * items DHCP will generate
 */

typedef struct dhcp_ddns_rdata {
	dns_rdata_t	rdata;
	dns_rdatalist_t rdatalist;
	dns_rdataset_t  rdataset;
} dhcp_ddns_data_t;

#if defined (NSUPDATE)

void ddns_interlude(isc_task_t  *, isc_event_t *);


#if defined (TRACING)
/*
 * Code to support tracing DDNS packets.  We trace packets going to and
 * coming from the libdns code but don't try to track the packets
 * exchanged between the libdns code and the dns server(s) it contacts.
 *
 * The code is split into two sets of routines
 *  input refers to messages received from the dns module
 *  output refers to messages sent to the dns module
 * Currently there are three routines in each set
 *  write is used to write information about the message to the trace file
 *        this routine is called directly from the proper place in the code.
 *  read is used to read information about a message from the trace file
 *       this routine is called from the trace loop as it reads through
 *       the file and is registered via the trace_type_register routine.
 *       When playing back a trace file we shall absorb records of output
 *       messages as part of processing the write function, therefore
 *       any output messages we encounter are flagged as errors.
 *  stop isn't currently used in this code but is needed for the register
 *       routine.
 *
 * We pass a pointer to a control block to the dns module which it returns
 * to use as part of the result.  As the pointer may vary between traces
 * we need to map between those from the trace file and the new ones during
 * playback.
 *
 * The mapping is complicated a little as a pointer could be 4 or 8 bytes
 * long.  We treat the old pointer as an 8 byte quantity and pad and compare
 * as necessary.
 */

/*
 * Structure used to map old pointers to new pointers.
 * Old pointers are 8 bytes long as we don't know if the trace was 
 * done on a 64 bit or 32 bit machine.  
 */
#define TRACE_PTR_LEN 8

typedef struct dhcp_ddns_map {
	char  old_pointer[TRACE_PTR_LEN];
	void *new_pointer;
	struct dhcp_ddns_map *next;
} dhcp_ddns_map_t;

/* The starting point for the map structure */
static dhcp_ddns_map_t *ddns_map;

trace_type_t *trace_ddns_input;
trace_type_t *trace_ddns_output;

/*
 * The data written to the trace file is:
 * 32 bits result from dns
 * 64 bits pointer of cb
 */

void
trace_ddns_input_write(dhcp_ddns_cb_t *ddns_cb, isc_result_t result)
{
	trace_iov_t iov[2];
	u_int32_t old_result;
	char old_pointer[TRACE_PTR_LEN];
	
	old_result = htonl((u_int32_t)result);
	memset(old_pointer, 0, TRACE_PTR_LEN);
	memcpy(old_pointer, &ddns_cb, sizeof(ddns_cb));

	iov[0].len = sizeof(old_result);
	iov[0].buf = (char *)&old_result;
	iov[1].len = TRACE_PTR_LEN;
	iov[1].buf = old_pointer;
	trace_write_packet_iov(trace_ddns_input, 2, iov, MDL);
}

/*
 * Process the result and pointer from the trace file.
 * We use the pointer map to find the proper pointer for this instance.
 * Then we need to construct an event to pass along to the interlude
 * function.
 */
static void
trace_ddns_input_read(trace_type_t *ttype, unsigned length,
				  char *buf)
{
	u_int32_t old_result;
	char old_pointer[TRACE_PTR_LEN];
	dns_clientupdateevent_t *eventp;
	void *new_pointer;
	dhcp_ddns_map_t *ddns_map_ptr;

	if (length < (sizeof(old_result) + TRACE_PTR_LEN)) {
		log_error("trace_ddns_input_read: data too short");
		return;
	}

	memcpy(&old_result, buf, sizeof(old_result));
	memcpy(old_pointer, buf + sizeof(old_result), TRACE_PTR_LEN);

	/* map the old pointer to a new pointer */
	for (ddns_map_ptr = ddns_map;
	     ddns_map_ptr != NULL;
	     ddns_map_ptr = ddns_map_ptr->next) {
		if ((ddns_map_ptr->new_pointer != NULL) &&
		    memcmp(ddns_map_ptr->old_pointer,
			   old_pointer, TRACE_PTR_LEN) == 0) {
			new_pointer = ddns_map_ptr->new_pointer;
			ddns_map_ptr->new_pointer = NULL;
			memset(ddns_map_ptr->old_pointer, 0, TRACE_PTR_LEN);
			break;
		}
	}
	if (ddns_map_ptr == NULL) {
		log_error("trace_dns_input_read: unable to map cb pointer");
		return;
	}		

	eventp = (dns_clientupdateevent_t *)
		isc_event_allocate(dhcp_gbl_ctx.mctx,
				   dhcp_gbl_ctx.task,
				   0,
				   ddns_interlude,
				   new_pointer,
				   sizeof(dns_clientupdateevent_t));
	if (eventp == NULL) {
		log_error("trace_ddns_input_read: unable to allocate event");
		return;
	}
	eventp->result = ntohl(old_result);


	ddns_interlude(dhcp_gbl_ctx.task, (isc_event_t *)eventp);

	return;
}

static void
trace_ddns_input_stop(trace_type_t *ttype)
{
}

/*
 * We use the same arguments as for the dns startupdate function to
 * allows us to choose between the two via a macro.  If tracing isn't
 * in use we simply call the dns function directly.
 *
 * If we are doing playback we read the next packet from the file
 * and compare the type.  If it matches we extract the results and pointer
 * from the trace file.  The results are returned to the caller as if
 * they had called the dns routine.  The pointer is used to construct a 
 * map for when the "reply" is processed.
 *
 * The data written to trace file is:
 * 32 bits result
 * 64 bits pointer of cb (DDNS Control block)
 * contents of cb
 */

isc_result_t
trace_ddns_output_write(dns_client_t *client, dns_rdataclass_t rdclass,
			dns_name_t *zonename, dns_namelist_t *prerequisites,
			dns_namelist_t *updates, isc_sockaddrlist_t *servers,
			dns_tsec_t *tsec, unsigned int options,
			isc_task_t *task, isc_taskaction_t action, void *arg,
			dns_clientupdatetrans_t **transp)
{
	isc_result_t result;
	u_int32_t old_result;
	char old_pointer[TRACE_PTR_LEN];
	dhcp_ddns_map_t *ddns_map_ptr;
	
	if (trace_playback() != 0) {
		/* We are doing playback, extract the entry from the file */
		unsigned buflen = 0;
		char *inbuf = NULL;

		result = trace_get_packet(&trace_ddns_output,
					  &buflen, &inbuf);
		if (result != ISC_R_SUCCESS) {
			log_error("trace_ddns_output_write: no input found");
			return (ISC_R_FAILURE);
		}
		if (buflen < (sizeof(old_result) + TRACE_PTR_LEN)) {
			log_error("trace_ddns_output_write: data too short");
			dfree(inbuf, MDL);
			return (ISC_R_FAILURE);
		}
		memcpy(&old_result, inbuf, sizeof(old_result));
		result = ntohl(old_result);
		memcpy(old_pointer, inbuf + sizeof(old_result), TRACE_PTR_LEN);
		dfree(inbuf, MDL);

		/* add the pointer to the pointer map */
		for (ddns_map_ptr = ddns_map;
		     ddns_map_ptr != NULL;
		     ddns_map_ptr = ddns_map_ptr->next) {
			if (ddns_map_ptr->new_pointer == NULL) {
				break;
			}
		}

		/*
		 * If we didn't find an empty entry, allocate an entry and
		 * link it into the list.  The list isn't ordered.
		 */
		if (ddns_map_ptr == NULL) {
			ddns_map_ptr = dmalloc(sizeof(*ddns_map_ptr), MDL);
			if (ddns_map_ptr == NULL) {
				log_error("trace_ddns_output_write: " 
					  "unable to allocate map entry");
				return(ISC_R_FAILURE);
				}
			ddns_map_ptr->next = ddns_map;
			ddns_map = ddns_map_ptr;
		}

		memcpy(ddns_map_ptr->old_pointer, old_pointer, TRACE_PTR_LEN);
		ddns_map_ptr->new_pointer = arg;
	}
	else {
		/* We aren't doing playback, make the actual call */
		result = dns_client_startupdate(client, rdclass, zonename,
						prerequisites, updates,
						servers, tsec, options,
						task, action, arg, transp);
	}

	if (trace_record() != 0) {
		/* We are recording, save the information to the file */
		trace_iov_t iov[3];
		old_result = htonl((u_int32_t)result);
		memset(old_pointer, 0, TRACE_PTR_LEN);
		memcpy(old_pointer, &arg, sizeof(arg));
		iov[0].len = sizeof(old_result);
		iov[0].buf = (char *)&old_result;
		iov[1].len = TRACE_PTR_LEN;
		iov[1].buf = old_pointer;

		/* Write out the entire cb, in case we want to look at it */
		iov[2].len = sizeof(dhcp_ddns_cb_t);
		iov[2].buf = (char *)arg;

		trace_write_packet_iov(trace_ddns_output, 3, iov, MDL);
	}

	return(result);
}

static void
trace_ddns_output_read(trace_type_t *ttype, unsigned length,
				   char *buf)
{
	log_error("unaccounted for ddns output.");
}

static void
trace_ddns_output_stop(trace_type_t *ttype)
{
}

void
trace_ddns_init()
{
	trace_ddns_output = trace_type_register("ddns-output", NULL,
						trace_ddns_output_read,
						trace_ddns_output_stop, MDL);
	trace_ddns_input  = trace_type_register("ddns-input", NULL,
						trace_ddns_input_read,
						trace_ddns_input_stop, MDL);
	ddns_map = NULL;
}

#define ddns_update trace_ddns_output_write
#else
#define ddns_update dns_client_startupdate
#endif /* TRACING */

/*
 * Code to allocate and free a dddns control block.  This block is used
 * to pass and track the information associated with a DDNS update request.
 */
dhcp_ddns_cb_t *
ddns_cb_alloc(const char *file, int line)
{
	dhcp_ddns_cb_t *ddns_cb;
	int i;

	ddns_cb = dmalloc(sizeof(*ddns_cb), file, line);
	if (ddns_cb != NULL) {
		ISC_LIST_INIT(ddns_cb->zone_server_list);
		for (i = 0; i < DHCP_MAXNS; i++) {
			ISC_LINK_INIT(&ddns_cb->zone_addrs[i], link);
		}
	}

#if defined (DEBUG_DNS_UPDATES)
	log_info("%s(%d): Allocating ddns_cb=%p", file, line, ddns_cb);
#endif

	return(ddns_cb);
}
		
void
ddns_cb_free(dhcp_ddns_cb_t *ddns_cb, const char *file, int line)
{
#if defined (DEBUG_DNS_UPDATES)
	log_info("%s(%d): freeing ddns_cb=%p", file, line, ddns_cb);
#endif

  	data_string_forget(&ddns_cb->fwd_name, file, line);
	data_string_forget(&ddns_cb->rev_name, file, line);
	data_string_forget(&ddns_cb->dhcid, file, line);
	
	if (ddns_cb->zone != NULL) {
		forget_zone((struct dns_zone **)&ddns_cb->zone);
	}

	/* Should be freed by now, check just in case. */
	if (ddns_cb->transaction != NULL)
		log_error("Impossible memory leak at %s:%d (attempt to free "
			  "DDNS Control Block before transaction).", MDL);

	dfree(ddns_cb, file, line);
}

void
ddns_cb_forget_zone(dhcp_ddns_cb_t *ddns_cb)
{
	int i;

	forget_zone(&ddns_cb->zone);
	ddns_cb->zone_name[0] = 0;
	ISC_LIST_INIT(ddns_cb->zone_server_list);
	for (i = 0; i < DHCP_MAXNS; i++) {
		ISC_LINK_INIT(&ddns_cb->zone_addrs[i], link);
	}
}

isc_result_t find_tsig_key (ns_tsig_key **key, const char *zname,
			    struct dns_zone *zone)
{
	ns_tsig_key *tkey;

	if (!zone)
		return ISC_R_NOTFOUND;

	if (!zone -> key) {
		return DHCP_R_KEY_UNKNOWN;
	}
	
	if ((!zone -> key -> name ||
	     strlen (zone -> key -> name) > NS_MAXDNAME) ||
	    (!zone -> key -> algorithm ||
	     strlen (zone -> key -> algorithm) > NS_MAXDNAME) ||
	    (!zone -> key) ||
	    (!zone -> key -> key) ||
	    (zone -> key -> key -> len == 0)) {
		return DHCP_R_INVALIDKEY;
	}
	tkey = dmalloc (sizeof *tkey, MDL);
	if (!tkey) {
	      nomem:
		return ISC_R_NOMEMORY;
	}
	memset (tkey, 0, sizeof *tkey);
	tkey -> data = dmalloc (zone -> key -> key -> len, MDL);
	if (!tkey -> data) {
		dfree (tkey, MDL);
		goto nomem;
	}
	strcpy (tkey -> name, zone -> key -> name);
	strcpy (tkey -> alg, zone -> key -> algorithm);
	memcpy (tkey -> data,
		zone -> key -> key -> value, zone -> key -> key -> len);
	tkey -> len = zone -> key -> key -> len;
	*key = tkey;
	return ISC_R_SUCCESS;
}

void tkey_free (ns_tsig_key **key)
{
	if ((*key) -> data)
		dfree ((*key) -> data, MDL);
	dfree ((*key), MDL);
	*key = (ns_tsig_key *)0;
}
#endif

isc_result_t enter_dns_zone (struct dns_zone *zone)
{
	struct dns_zone *tz = (struct dns_zone *)0;

	if (dns_zone_hash) {
		dns_zone_hash_lookup (&tz,
				      dns_zone_hash, zone -> name, 0, MDL);
		if (tz == zone) {
			dns_zone_dereference (&tz, MDL);
			return ISC_R_SUCCESS;
		}
		if (tz) {
			dns_zone_hash_delete (dns_zone_hash,
					      zone -> name, 0, MDL);
			dns_zone_dereference (&tz, MDL);
		}
	} else {
		if (!dns_zone_new_hash(&dns_zone_hash, DNS_HASH_SIZE, MDL))
			return ISC_R_NOMEMORY;
	}

	dns_zone_hash_add (dns_zone_hash, zone -> name, 0, zone, MDL);
	return ISC_R_SUCCESS;
}

isc_result_t dns_zone_lookup (struct dns_zone **zone, const char *name)
{
	int len;
	char *tname = (char *)0;
	isc_result_t status;

	if (!dns_zone_hash)
		return ISC_R_NOTFOUND;

	len = strlen (name);
	if (name [len - 1] != '.') {
		tname = dmalloc ((unsigned)len + 2, MDL);
		if (!tname)
			return ISC_R_NOMEMORY;
		strcpy (tname, name);
		tname [len] = '.';
		tname [len + 1] = 0;
		name = tname;
	}
	if (!dns_zone_hash_lookup (zone, dns_zone_hash, name, 0, MDL))
		status = ISC_R_NOTFOUND;
	else
		status = ISC_R_SUCCESS;

	if (tname)
		dfree (tname, MDL);
	return status;
}

int dns_zone_dereference (ptr, file, line)
	struct dns_zone **ptr;
	const char *file;
	int line;
{
	struct dns_zone *dns_zone;

	if ((ptr == NULL) || (*ptr == NULL)) {
		log_error("%s(%d): null pointer", file, line);
#if defined (POINTER_DEBUG)
		abort();
#else
		return (0);
#endif
	}

	dns_zone = *ptr;
	*ptr = NULL;
	--dns_zone->refcnt;
	rc_register(file, line, ptr, dns_zone, dns_zone->refcnt, 1, RC_MISC);
	if (dns_zone->refcnt > 0)
		return (1);

	if (dns_zone->refcnt < 0) {
		log_error("%s(%d): negative refcnt!", file, line);
#if defined (DEBUG_RC_HISTORY)
		dump_rc_history(dns_zone);
#endif
#if defined (POINTER_DEBUG)
		abort();
#else
		return (0);
#endif
	}

	if (dns_zone->name)
		dfree(dns_zone->name, file, line);
	if (dns_zone->key)
		omapi_auth_key_dereference(&dns_zone->key, file, line);
	if (dns_zone->primary)
		option_cache_dereference(&dns_zone->primary, file, line);
	if (dns_zone->secondary)
		option_cache_dereference(&dns_zone->secondary, file, line);
	if (dns_zone->primary6)
		option_cache_dereference(&dns_zone->primary6, file, line);
	if (dns_zone->secondary6)
		option_cache_dereference(&dns_zone->secondary6, file, line);
	dfree(dns_zone, file, line);
	return (1);
}

#if defined (NSUPDATE)
isc_result_t
find_cached_zone(dhcp_ddns_cb_t *ddns_cb, int direction) 
{
	isc_result_t status = ISC_R_NOTFOUND;
	const char *np;
	struct dns_zone *zone = NULL;
	struct data_string nsaddrs;
	struct in_addr zone_addr;
	struct in6_addr zone_addr6;
	int ix;

	if (direction == FIND_FORWARD) {
		np = (const char *)ddns_cb->fwd_name.data;
	} else {
		np = (const char *)ddns_cb->rev_name.data;
	}

	/* We can't look up a null zone. */
	if ((np == NULL) || (*np == '\0')) {
		return (DHCP_R_INVALIDARG);
	}

	/*
	 * For each subzone, try to find a cached zone.
	 */
	for (;;) {
		status = dns_zone_lookup(&zone, np);
		if (status == ISC_R_SUCCESS)
			break;

		np = strchr(np, '.');
		if (np == NULL)
			break;
		np++;
	}

	if (status != ISC_R_SUCCESS)
		return (status);

	/* Make sure the zone is valid. */
	if (zone->timeout && zone->timeout < cur_time) {
		dns_zone_dereference(&zone, MDL);
		return (ISC_R_CANCELED);
	}

	/* Make sure the zone name will fit. */
	if (strlen(zone->name) > sizeof(ddns_cb->zone_name)) {
		dns_zone_dereference(&zone, MDL);
		return (ISC_R_NOSPACE);
	}
	strcpy((char *)&ddns_cb->zone_name[0], zone->name);

	memset (&nsaddrs, 0, sizeof nsaddrs);
	ix = 0;

	if (zone->primary) {
		if (evaluate_option_cache(&nsaddrs, NULL, NULL, NULL,
					  NULL, NULL, &global_scope,
					  zone->primary, MDL)) {
			int ip = 0;
			while (ix < DHCP_MAXNS) {
				if (ip + 4 > nsaddrs.len)
					break;
				memcpy(&zone_addr, &nsaddrs.data[ip], 4);
				isc_sockaddr_fromin(&ddns_cb->zone_addrs[ix],
						    &zone_addr,
						    NS_DEFAULTPORT);
				ISC_LIST_APPEND(ddns_cb->zone_server_list,
						&ddns_cb->zone_addrs[ix],
						link);
				ip += 4;
				ix++;
			}
			data_string_forget(&nsaddrs, MDL);
		}
	}

	if (zone->primary6) {
		if (evaluate_option_cache(&nsaddrs, NULL, NULL, NULL,
					  NULL, NULL, &global_scope,
					  zone->primary6, MDL)) {
			int ip = 0;
			while (ix < DHCP_MAXNS) {
				if (ip + 16 > nsaddrs.len)
					break;
				memcpy(&zone_addr6, &nsaddrs.data[ip], 16);
				isc_sockaddr_fromin6(&ddns_cb->zone_addrs[ix],
						    &zone_addr6,
						    NS_DEFAULTPORT);
				ISC_LIST_APPEND(ddns_cb->zone_server_list,
						&ddns_cb->zone_addrs[ix],
						link);
				ip += 16;
				ix++;
			}
			data_string_forget(&nsaddrs, MDL);
		}
	}

	if (zone->secondary) {
		if (evaluate_option_cache(&nsaddrs, NULL, NULL, NULL,
					  NULL, NULL, &global_scope,
					  zone->secondary, MDL)) {
			int ip = 0;
			while (ix < DHCP_MAXNS) {
				if (ip + 4 > nsaddrs.len)
					break;
				memcpy(&zone_addr, &nsaddrs.data[ip], 4);
				isc_sockaddr_fromin(&ddns_cb->zone_addrs[ix],
						    &zone_addr,
						    NS_DEFAULTPORT);
				ISC_LIST_APPEND(ddns_cb->zone_server_list,
						&ddns_cb->zone_addrs[ix],
						link);
				ip += 4;
				ix++;
			}
			data_string_forget (&nsaddrs, MDL);
		}
	}

	if (zone->secondary6) {
		if (evaluate_option_cache(&nsaddrs, NULL, NULL, NULL,
					  NULL, NULL, &global_scope,
					  zone->secondary6, MDL)) {
			int ip = 0;
			while (ix < DHCP_MAXNS) {
				if (ip + 16 > nsaddrs.len)
					break;
				memcpy(&zone_addr6, &nsaddrs.data[ip], 16);
				isc_sockaddr_fromin6(&ddns_cb->zone_addrs[ix],
						    &zone_addr6,
						    NS_DEFAULTPORT);
				ISC_LIST_APPEND(ddns_cb->zone_server_list,
						&ddns_cb->zone_addrs[ix],
						link);
				ip += 16;
				ix++;
			}
			data_string_forget (&nsaddrs, MDL);
		}
	}

	dns_zone_reference(&ddns_cb->zone, zone, MDL);
	dns_zone_dereference (&zone, MDL);
	return ISC_R_SUCCESS;
}

void forget_zone (struct dns_zone **zone)
{
	dns_zone_dereference (zone, MDL);
}

void repudiate_zone (struct dns_zone **zone)
{
	/* XXX Currently we're not differentiating between a cached
	   XXX zone and a zone that's been repudiated, which means
	   XXX that if we reap cached zones, we blow away repudiated
	   XXX zones.   This isn't a big problem since we're not yet
	   XXX caching zones... :'} */

	/* verify that we have a pointer at least */
	if ((zone == NULL) || (*zone == NULL)) {
		log_info("Null argument to repudiate zone");
		return;
	}

	(*zone) -> timeout = cur_time - 1;
	dns_zone_dereference (zone, MDL);
}

/* Have to use TXT records for now. */
#define T_DHCID T_TXT

int get_dhcid (struct data_string *id,
	       int type, const u_int8_t *data, unsigned len)
{
	unsigned char buf[ISC_MD5_DIGESTLENGTH];
	isc_md5_t md5;
	int i;

	/* Types can only be 0..(2^16)-1. */
	if (type < 0 || type > 65535)
		return 0;

	/*
	 * Hexadecimal MD5 digest plus two byte type, NUL,
	 * and one byte for length for dns.
	 */
	if (!buffer_allocate (&id -> buffer,
			      (ISC_MD5_DIGESTLENGTH * 2) + 4, MDL))
		return 0;
	id -> data = id -> buffer -> data;

	/*
	 * DHCP clients and servers should use the following forms of client
	 * identification, starting with the most preferable, and finishing
	 * with the least preferable.  If the client does not send any of these
	 * forms of identification, the DHCP/DDNS interaction is not defined by
	 * this specification.  The most preferable form of identification is
	 * the Globally Unique Identifier Option [TBD].  Next is the DHCP
	 * Client Identifier option.  Last is the client's link-layer address,
	 * as conveyed in its DHCPREQUEST message.  Implementors should note
	 * that the link-layer address cannot be used if there are no
	 * significant bytes in the chaddr field of the DHCP client's request,
	 * because this does not constitute a unique identifier.
	 *   -- "Interaction between DHCP and DNS"
	 *      <draft-ietf-dhc-dhcp-dns-12.txt>
	 *      M. Stapp, Y. Rekhter
	 *
	 * We put the length into the first byte to turn 
	 * this into a dns text string.  This avoid needing to
	 * copy the string to add the byte later.
	 */
	id->buffer->data[0] = ISC_MD5_DIGESTLENGTH * 2 + 2;

	/* Put the type in the next two bytes. */
	id->buffer->data[1] = "0123456789abcdef"[(type >> 4) & 0xf];
	/* This should have been [type & 0xf] but now that
	 * it is in use we need to leave it this way in order
	 * to avoid disturbing customer's lease files
	 */
	id->buffer->data[2] = "0123456789abcdef"[type % 15];
  
	/* Mash together an MD5 hash of the identifier. */
	isc_md5_init(&md5);
	isc_md5_update(&md5, data, len);
	isc_md5_final(&md5, buf);

	/* Convert into ASCII. */
	for (i = 0; i < ISC_MD5_DIGESTLENGTH; i++) {
		id->buffer->data[i * 2 + 3] =
			"0123456789abcdef"[(buf[i] >> 4) & 0xf];
		id->buffer->data[i * 2 + 4] =
			"0123456789abcdef"[buf[i] & 0xf];
	}

	id->len = ISC_MD5_DIGESTLENGTH * 2 + 3;
	id->buffer->data[id->len] = 0;
	id->terminated = 1;

	return 1;
}

/*
 * The dhcid (text version) that we pass to DNS includes a length byte
 * at the start but the text we store in the lease doesn't include the
 * length byte.  The following routines are to convert between the two
 * styles.
 *
 * When converting from a dhcid to a leaseid we reuse the buffer and
 * simply adjust the data pointer and length fields in the data string.
 * This avoids any prolems with allocating space.
 */

void
dhcid_tolease(struct data_string *dhcid,
	      struct data_string *leaseid)
{
	/* copy the data string then update the fields */
	data_string_copy(leaseid, dhcid, MDL);
	leaseid->data++;
	leaseid->len--;
}

isc_result_t
dhcid_fromlease(struct data_string *dhcid,
		struct data_string *leaseid)
{
	if (!buffer_allocate(&dhcid->buffer, leaseid->len + 2, MDL)) {
		return(ISC_R_FAILURE);
	}

	dhcid->data = dhcid->buffer->data;

	dhcid->buffer->data[0] = leaseid->len;
	memcpy(dhcid->buffer->data + 1, leaseid->data, leaseid->len);
	dhcid->len = leaseid->len + 1;
	if (leaseid->terminated == 1) {
		dhcid->buffer->data[dhcid->len] = 0;
		dhcid->terminated = 1;
	}

	return(ISC_R_SUCCESS);
}

/* 
 * Construct the dataset for this item.
 * This is a fairly simple arrangement as the operations we do are simple.
 * If there is data we simply have the rdata point to it - the formatting
 * must be correct already.  We then link the rdatalist to the rdata and
 * create a rdataset from the rdatalist.
 */

static isc_result_t
make_dns_dataset(dns_rdataclass_t  dataclass,
		 dns_rdatatype_t   datatype,
		 dhcp_ddns_data_t *dataspace,
		 unsigned char    *data,
		 int               datalen,
		 int               ttl)
{
	dns_rdata_t *rdata = &dataspace->rdata;
	dns_rdatalist_t *rdatalist = &dataspace->rdatalist;
	dns_rdataset_t *rdataset = &dataspace->rdataset;

	isc_region_t region;

	/* set up the rdata */
	dns_rdata_init(rdata);

	if (data == NULL) {
		/* No data, set up the rdata fields we care about */
		rdata->flags = DNS_RDATA_UPDATE;
		rdata->type = datatype;
		rdata->rdclass = dataclass;
	} else {
		switch(datatype) {
		case dns_rdatatype_a:
		case dns_rdatatype_aaaa:
		case dns_rdatatype_txt:
		case dns_rdatatype_dhcid:
		case dns_rdatatype_ptr:
			/* The data must be in the right format we simply
			 * need to supply it via the correct structure */
			region.base   = data;
			region.length = datalen;
			dns_rdata_fromregion(rdata, dataclass, datatype,
					     &region);
			break;
		default:
			return(DHCP_R_INVALIDARG);
			break;
		}
	}

	/* setup the datalist and attach the rdata to it */
	dns_rdatalist_init(rdatalist);
	rdatalist->type = datatype;
	rdatalist->rdclass = dataclass;
	rdatalist->ttl = ttl;
	ISC_LIST_APPEND(rdatalist->rdata, rdata, link);

	/* convert the datalist to a dataset */
	dns_rdataset_init(rdataset);
	dns_rdatalist_tordataset(rdatalist, rdataset);

	return(ISC_R_SUCCESS);
}

/*
 * When a DHCP client or server intends to update an A RR, it first
 * prepares a DNS UPDATE query which includes as a prerequisite the
 * assertion that the name does not exist.  The update section of the
 * query attempts to add the new name and its IP address mapping (an A
 * RR), and the DHCID RR with its unique client-identity.
 *   -- "Interaction between DHCP and DNS"
 *
 * There are two cases, one for the server and one for the client.
 *
 * For the server the first step will have a request of:
 * The name is not in use
 * Add an A RR
 * Add a DHCID RR (currently txt)
 *
 * For the client the first step will have a request of:
 * The A RR does not exist
 * Add an A RR
 * Add a DHCID RR (currently txt)
 */

static isc_result_t
ddns_modify_fwd_add1(dhcp_ddns_cb_t   *ddns_cb,
		     dhcp_ddns_data_t *dataspace,
		     dns_name_t       *pname,
		     dns_name_t       *uname)
{
	isc_result_t result;

	/* Construct the prerequisite list */
	if ((ddns_cb->flags & DDNS_INCLUDE_RRSET) != 0) {
		/* The A RR shouldn't exist */
		result = make_dns_dataset(dns_rdataclass_none,
					  ddns_cb->address_type,
					  dataspace, NULL, 0, 0);
	} else {
		/* The name is not in use */
		result = make_dns_dataset(dns_rdataclass_none,
					  dns_rdatatype_any,
					  dataspace, NULL, 0, 0);
	}
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(pname->list, &dataspace->rdataset, link);
	dataspace++;

	/* Construct the update list */
	/* Add the A RR */
	result = make_dns_dataset(dns_rdataclass_in, ddns_cb->address_type,
				  dataspace, 
				  (unsigned char *)ddns_cb->address.iabuf,
				  ddns_cb->address.len, ddns_cb->ttl);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(uname->list, &dataspace->rdataset, link);
	dataspace++;

	/* Add the DHCID RR */
	result = make_dns_dataset(dns_rdataclass_in, dns_rdatatype_txt,
				  dataspace, 
				  (unsigned char *)ddns_cb->dhcid.data,
				  ddns_cb->dhcid.len, ddns_cb->ttl);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(uname->list, &dataspace->rdataset, link);

	return(ISC_R_SUCCESS);
}

/*
 * If the first update operation fails with YXDOMAIN, the updater can
 * conclude that the intended name is in use.  The updater then
 * attempts to confirm that the DNS name is not being used by some
 * other host. The updater prepares a second UPDATE query in which the
 * prerequisite is that the desired name has attached to it a DHCID RR
 * whose contents match the client identity.  The update section of
 * this query deletes the existing A records on the name, and adds the
 * A record that matches the DHCP binding and the DHCID RR with the
 * client identity.
 *   -- "Interaction between DHCP and DNS"
 *
 * The message for the second step depends on if we are doing conflict
 * resolution.  If we are we include a prerequisite.  If not we delete
 * the DHCID in addition to all A rrsets.
 *
 * Conflict resolution:
 * DHCID RR exists, and matches client identity.
 * Delete A RRset.
 * Add A RR.
 *
 * Conflict override:
 * Delete DHCID RRs.
 * Add DHCID RR
 * Delete A RRset.
 * Add A RR.
 */

static isc_result_t
ddns_modify_fwd_add2(dhcp_ddns_cb_t   *ddns_cb,
		     dhcp_ddns_data_t *dataspace,
		     dns_name_t       *pname,
		     dns_name_t       *uname)
{
	isc_result_t result;

	/*
	 * If we are doing conflict resolution (unset) we use a prereq list.
	 * If not we delete the DHCID in addition to all A rrsets.
	 */
	if ((ddns_cb->flags & DDNS_CONFLICT_OVERRIDE) == 0) {
		/* Construct the prereq list */
		/* The DHCID RR exists and matches the client identity */
		result = make_dns_dataset(dns_rdataclass_in, dns_rdatatype_txt,
					  dataspace, 
					  (unsigned char *)ddns_cb->dhcid.data,
					  ddns_cb->dhcid.len, 0);
		if (result != ISC_R_SUCCESS) {
			return(result);
		}
		ISC_LIST_APPEND(pname->list, &dataspace->rdataset, link);
		dataspace++;
	} else {
		/* Start constructing the update list.
		 * Conflict detection override: delete DHCID RRs */
		result = make_dns_dataset(dns_rdataclass_any,
					  dns_rdatatype_txt,
					  dataspace, NULL, 0, 0);
		if (result != ISC_R_SUCCESS) {
			return(result);
		}
		ISC_LIST_APPEND(uname->list, &dataspace->rdataset, link);
		dataspace++;

		/* Add current DHCID RR */
		result = make_dns_dataset(dns_rdataclass_in, dns_rdatatype_txt,
					  dataspace, 
					  (unsigned char *)ddns_cb->dhcid.data,
					  ddns_cb->dhcid.len, ddns_cb->ttl);
		if (result != ISC_R_SUCCESS) {
			return(result);
		}
		ISC_LIST_APPEND(uname->list, &dataspace->rdataset, link);
		dataspace++;
	}

	/* Start or continue constructing the update list */
	/* Delete the A RRset */
	result = make_dns_dataset(dns_rdataclass_any, ddns_cb->address_type,
				  dataspace, NULL, 0, 0);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(uname->list, &dataspace->rdataset, link);
	dataspace++;

	/* Add the A RR */
	result = make_dns_dataset(dns_rdataclass_in, ddns_cb->address_type,
				  dataspace, 
				  (unsigned char *)ddns_cb->address.iabuf,
				  ddns_cb->address.len, ddns_cb->ttl);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(uname->list, &dataspace->rdataset, link);

	return(ISC_R_SUCCESS);
}

/*
 * The entity chosen to handle the A record for this client (either the
 * client or the server) SHOULD delete the A record that was added when
 * the lease was made to the client.
 *
 * In order to perform this delete, the updater prepares an UPDATE
 * query which contains two prerequisites.  The first prerequisite
 * asserts that the DHCID RR exists whose data is the client identity
 * described in Section 4.3. The second prerequisite asserts that the
 * data in the A RR contains the IP address of the lease that has
 * expired or been released.
 *   -- "Interaction between DHCP and DNS"
 *
 * First try has:
 * DHCID RR exists, and matches client identity.
 * A RR matches the expiring lease.
 * Delete appropriate A RR.
 */

static isc_result_t
ddns_modify_fwd_rem1(dhcp_ddns_cb_t   *ddns_cb,
		     dhcp_ddns_data_t *dataspace,
		     dns_name_t       *pname,
		     dns_name_t       *uname)
{
	isc_result_t result;

	/* Consruct the prereq list */
	/* The DHCID RR exists and matches the client identity */
	result = make_dns_dataset(dns_rdataclass_in, dns_rdatatype_txt,
				  dataspace, 
				  (unsigned char *)ddns_cb->dhcid.data,
				  ddns_cb->dhcid.len, 0);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(pname->list, &dataspace->rdataset, link);
	dataspace++;

	/* The A RR matches the expiring lease */
	result = make_dns_dataset(dns_rdataclass_in, ddns_cb->address_type,
				  dataspace, 
				  (unsigned char *)ddns_cb->address.iabuf,
				  ddns_cb->address.len, 0);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(pname->list, &dataspace->rdataset, link);
	dataspace++;

	/* Construct the update list */
	/* Delete A RRset */
	result = make_dns_dataset(dns_rdataclass_none, ddns_cb->address_type,
				  dataspace,
				  (unsigned char *)ddns_cb->address.iabuf,
				  ddns_cb->address.len, 0);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(uname->list, &dataspace->rdataset, link);

	return(ISC_R_SUCCESS);
}

/*
 * If the deletion of the A succeeded, and there are no A or AAAA
 * records left for this domain, then we can blow away the DHCID
 * record as well.   We can't blow away the DHCID record above
 * because it's possible that more than one record has been added
 * to this domain name.
 *
 * Second query has:
 * A RR does not exist.
 * AAAA RR does not exist.
 * Delete appropriate DHCID RR.
 */

static isc_result_t
ddns_modify_fwd_rem2(dhcp_ddns_cb_t   *ddns_cb,
		     dhcp_ddns_data_t *dataspace,
		     dns_name_t       *pname,
		     dns_name_t       *uname)
{
	isc_result_t result;

	/* Construct the prereq list */
	/* The A RR does not exist */
	result = make_dns_dataset(dns_rdataclass_none, dns_rdatatype_a,
				  dataspace, NULL, 0, 0);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(pname->list, &dataspace->rdataset, link);
	dataspace++;

	/* The AAAA RR does not exist */
	result = make_dns_dataset(dns_rdataclass_none, dns_rdatatype_aaaa,
				  dataspace, NULL, 0, 0);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(pname->list, &dataspace->rdataset, link);
	dataspace++;

	/* Construct the update list */
	/* Delete DHCID RR */
	result = make_dns_dataset(dns_rdataclass_none, dns_rdatatype_txt,
				  dataspace,
				  (unsigned char *)ddns_cb->dhcid.data,
				  ddns_cb->dhcid.len, 0);
	if (result != ISC_R_SUCCESS) {
		return(result);
	}
	ISC_LIST_APPEND(uname->list, &dataspace->rdataset, link);

	return(ISC_R_SUCCESS);
}

/*
 * This routine converts from the task action call into something
 * easier to work with.  It also handles the common case of a signature
 * or zone not being correct.
 */
void ddns_interlude(isc_task_t  *taskp,
		    isc_event_t *eventp)
{
	dhcp_ddns_cb_t *ddns_cb = (dhcp_ddns_cb_t *)eventp->ev_arg;
	dns_clientupdateevent_t *ddns_event = (dns_clientupdateevent_t *)eventp;
	isc_result_t eresult = ddns_event->result;
	isc_result_t result;

	/* We've extracted the information we want from it, get rid of
	 * the event block.*/
	isc_event_free(&eventp);

#if defined (TRACING)
	if (trace_record()) {
		trace_ddns_input_write(ddns_cb, eresult);
	}
#endif

#if defined (DEBUG_DNS_UPDATES)
	print_dns_status(DDNS_PRINT_INBOUND, ddns_cb, eresult);
#endif

	/* This transaction is complete, clear the value */
	dns_client_destroyupdatetrans(&ddns_cb->transaction);

	/* If we cancelled or tried to cancel the operation we just
	 * need to clean up. */
	if ((eresult == ISC_R_CANCELED) ||
	    ((ddns_cb->flags & DDNS_ABORT) != 0)) {
#if defined (DEBUG_DNS_UPDATES)
		log_info("DDNS: completeing transaction cancellation cb=%p, "
			 "flags=%x, %s",
			 ddns_cb, ddns_cb->flags, isc_result_totext(eresult));
#endif
		if ((ddns_cb->flags & DDNS_ABORT) == 0) {
			log_info("DDNS: cleaning up lease pointer for a cancel "
				 "cb=%p", ddns_cb);
			/* 
			 * We shouldn't actually be able to get here but
			 * we are.  This means we haven't cleaned up
			 * the lease pointer so we need to do that before
			 * freeing the cb.  
			 */
			ddns_cb->cur_func(ddns_cb, eresult);
			return;
		}

		if (ddns_cb->next_op != NULL) {
			/* if necessary cleanup up next op block */
			ddns_cb_free(ddns_cb->next_op, MDL);
		}
		ddns_cb_free(ddns_cb, MDL);
		return;
	}

	/* If we had a problem with our key or zone try again */
	if ((eresult == DNS_R_NOTAUTH) ||
	    (eresult == DNS_R_NOTZONE)) {
		int i;
		/* Our zone information was questionable,
		 * repudiate it and try again */
		log_error("DDNS: bad zone information, repudiating zone %s",
			  ddns_cb->zone_name);
		repudiate_zone(&ddns_cb->zone);
		ddns_cb->zone_name[0]    = 0;
		ISC_LIST_INIT(ddns_cb->zone_server_list);
		for (i = 0; i < DHCP_MAXNS; i++) {
			ISC_LINK_INIT(&ddns_cb->zone_addrs[i], link);
		}

		if ((ddns_cb->state == DDNS_STATE_ADD_PTR) ||
		    (ddns_cb->state == DDNS_STATE_REM_PTR)) {
			result = ddns_modify_ptr(ddns_cb, MDL);
		} else {
			result = ddns_modify_fwd(ddns_cb, MDL);
		}

		if (result != ISC_R_SUCCESS) {
			/* if we couldn't redo the query log it and
			 * let the next function clean it up */
			log_info("DDNS: Failed to retry after zone failure");
			ddns_cb->cur_func(ddns_cb, result);
		}
		return;
	} else {
		/* pass it along to be processed */
		ddns_cb->cur_func(ddns_cb, eresult);
	}
	
	return;
}

/*
 * This routine does the generic work for sending a ddns message to
 * modify the forward record (A or AAAA) and calls one of a set of
 * routines to build the specific message.
 */

isc_result_t
ddns_modify_fwd(dhcp_ddns_cb_t *ddns_cb, const char *file, int line)
{
	isc_result_t result;
	dns_tsec_t *tsec_key = NULL;

	unsigned char *clientname;
	dhcp_ddns_data_t *dataspace = NULL;
	dns_namelist_t prereqlist, updatelist;
	dns_fixedname_t zname0, pname0, uname0;
	dns_name_t *zname = NULL, *pname, *uname;

	isc_sockaddrlist_t *zlist = NULL;

	/* Get a pointer to the clientname to make things easier. */
	clientname = (unsigned char *)ddns_cb->fwd_name.data;

	/* Extract and validate the type of the address. */
	if (ddns_cb->address.len == 4) {
		ddns_cb->address_type = dns_rdatatype_a;
	} else if (ddns_cb->address.len == 16) {
		ddns_cb->address_type = dns_rdatatype_aaaa;
	} else {
		return DHCP_R_INVALIDARG;
	}

	/*
	 * If we already have a zone use it, otherwise try to lookup the
	 * zone in our cache.  If we find one we will have a pointer to
	 * the zone that needs to be dereferenced when we are done with it.
	 * If we don't find one that is okay we'll let the DNS code try and
	 * find the information for us.
	 */

	if (ddns_cb->zone == NULL) {
		result = find_cached_zone(ddns_cb, FIND_FORWARD);
	}

	/*
	 * If we have a zone try to get any information we need
	 * from it - name, addresses and the key.  The address 
	 * and key may be empty the name can't be.
	 */
	if (ddns_cb->zone) {
		/* Set up the zone name for use by DNS */
		result = dhcp_isc_name(ddns_cb->zone_name, &zname0, &zname);
		if (result != ISC_R_SUCCESS) {
			log_error("Unable to build name for zone for "
				  "fwd update: %s %s",
				  ddns_cb->zone_name,
				  isc_result_totext(result));
			goto cleanup;
		}

		if (!(ISC_LIST_EMPTY(ddns_cb->zone_server_list))) {
			/* If we have any addresses get them */
			zlist = &ddns_cb->zone_server_list;
		}
		

		if (ddns_cb->zone->key != NULL) {
			/*
			 * Not having a key is fine, having a key
			 * but not a tsec is odd so we warn the user.
			 */
			/*sar*/
			/* should we do the warning? */
			tsec_key = ddns_cb->zone->key->tsec_key;
			if (tsec_key == NULL) {
				log_error("No tsec for use with key %s",
					  ddns_cb->zone->key->name);
			}
		}
	}

	/* Set up the DNS names for the prereq and update lists */
	if (((result = dhcp_isc_name(clientname, &pname0, &pname))
	     != ISC_R_SUCCESS) ||
	    ((result = dhcp_isc_name(clientname, &uname0, &uname))
	     != ISC_R_SUCCESS)) {
		log_error("Unable to build name for fwd update: %s %s",
			  clientname, isc_result_totext(result));
		goto cleanup;
	}

	/* Allocate the various isc dns library structures we may require. */
	dataspace = isc_mem_get(dhcp_gbl_ctx.mctx, sizeof(*dataspace) * 4);
	if (dataspace == NULL) {
		log_error("Unable to allocate memory for fwd update");
		result = ISC_R_NOMEMORY; 
		goto cleanup;
	}

	ISC_LIST_INIT(prereqlist);
	ISC_LIST_INIT(updatelist);

	switch(ddns_cb->state) {
	case DDNS_STATE_ADD_FW_NXDOMAIN:
		result = ddns_modify_fwd_add1(ddns_cb, dataspace,
					      pname, uname);
		if (result != ISC_R_SUCCESS) {
			goto cleanup;
		}
		ISC_LIST_APPEND(prereqlist, pname, link);
		break;
	case DDNS_STATE_ADD_FW_YXDHCID:
		result = ddns_modify_fwd_add2(ddns_cb, dataspace,
					       pname, uname);
		if (result != ISC_R_SUCCESS) {
			goto cleanup;
		}

		/* If we aren't doing conflict override we have entries
		 * in the pname list and we need to attach it to the
		 * prereqlist */

		if ((ddns_cb->flags & DDNS_CONFLICT_OVERRIDE) == 0) {
			ISC_LIST_APPEND(prereqlist, pname, link);
		}

		break;
	case DDNS_STATE_REM_FW_YXDHCID:
		result = ddns_modify_fwd_rem1(ddns_cb, dataspace,
					      pname, uname);
		if (result != ISC_R_SUCCESS) {
			goto cleanup;
		}
		ISC_LIST_APPEND(prereqlist, pname, link);
		break;
	case DDNS_STATE_REM_FW_NXRR:
		result = ddns_modify_fwd_rem2(ddns_cb, dataspace,
					      pname, uname);
		if (result != ISC_R_SUCCESS) {
			goto cleanup;
		}
		ISC_LIST_APPEND(prereqlist, pname, link);
		break;

	default:
		log_error("Invalid operation in ddns code.");
		result = DHCP_R_INVALIDARG;
		goto cleanup;
		break;
	}

	/*
	 * We always have an update list but may not have a prereqlist
	 * if we are doing conflict override.
	 */
	ISC_LIST_APPEND(updatelist, uname, link);

	/* send the message, cleanup and return the result */
	result = ddns_update(dhcp_gbl_ctx.dnsclient,
			     dns_rdataclass_in, zname,
			     &prereqlist, &updatelist,
			     zlist, tsec_key,
			     DNS_CLIENTRESOPT_ALLOWRUN,
			     dhcp_gbl_ctx.task,
			     ddns_interlude,
			     (void *)ddns_cb,
			     &ddns_cb->transaction);
	if (result == ISC_R_FAMILYNOSUPPORT) {
		log_info("Unable to perform DDNS update, "
			 "address family not supported");
	}

#if defined (DEBUG_DNS_UPDATES)
	print_dns_status(DDNS_PRINT_OUTBOUND, ddns_cb, result);
#endif

 cleanup:
#if defined (DEBUG_DNS_UPDATES)
	if (result != ISC_R_SUCCESS) {
		log_info("DDNS: %s(%d): error in ddns_modify_fwd %s for %p",
			 file, line, isc_result_totext(result), ddns_cb);
	}
#endif

	if (dataspace != NULL) {
		isc_mem_put(dhcp_gbl_ctx.mctx, dataspace,
			    sizeof(*dataspace) * 4);
	}
	return(result);
}


isc_result_t
ddns_modify_ptr(dhcp_ddns_cb_t *ddns_cb, const char *file, int line)
{
	isc_result_t result;
	dns_tsec_t *tsec_key  = NULL;
	unsigned char *ptrname;
	dhcp_ddns_data_t *dataspace = NULL;
	dns_namelist_t updatelist;
	dns_fixedname_t zname0, uname0;
	dns_name_t *zname = NULL, *uname;
	isc_sockaddrlist_t *zlist = NULL;
	unsigned char buf[256];
	int buflen;

	/*
	 * Try to lookup the zone in the zone cache.  As with the forward
	 * case it's okay if we don't have one, the DNS code will try to
	 * find something also if we succeed we will need to dereference
	 * the zone later.  Unlike with the forward case we assume we won't
	 * have a pre-existing zone.
	 */
	result = find_cached_zone(ddns_cb, FIND_REVERSE);
	if ((result == ISC_R_SUCCESS) &&
	    !(ISC_LIST_EMPTY(ddns_cb->zone_server_list))) {
		/* Set up the zone name for use by DNS */
		result = dhcp_isc_name(ddns_cb->zone_name, &zname0, &zname);
		if (result != ISC_R_SUCCESS) {
			log_error("Unable to build name for zone for "
				  "fwd update: %s %s",
				  ddns_cb->zone_name,
				  isc_result_totext(result));
			goto cleanup;
		}
		/* If we have any addresses get them */
		if (!(ISC_LIST_EMPTY(ddns_cb->zone_server_list))) {
			zlist = &ddns_cb->zone_server_list;
		}

		/*
		 * If we now have a zone try to get the key, NULL is okay,
		 * having a key but not a tsec is odd so we warn.
		 */
		/*sar*/
		/* should we do the warning if we have a key but no tsec? */
		if ((ddns_cb->zone != NULL) && (ddns_cb->zone->key != NULL)) {
			tsec_key = ddns_cb->zone->key->tsec_key;
			if (tsec_key == NULL) {
				log_error("No tsec for use with key %s",
					  ddns_cb->zone->key->name);
			}
		}
	}

	/* We must have a name for the update list */
	/* Get a pointer to the ptrname to make things easier. */
	ptrname = (unsigned char *)ddns_cb->rev_name.data;

	if ((result = dhcp_isc_name(ptrname, &uname0, &uname))
	     != ISC_R_SUCCESS) {
		log_error("Unable to build name for fwd update: %s %s",
			  ptrname, isc_result_totext(result));
		goto cleanup;
	}

	/*
	 * Allocate the various isc dns library structures we may require.
	 * Allocating one blob avoids being halfway through the process
	 * and being unable to allocate as well as making the free easy.
	 */
	dataspace = isc_mem_get(dhcp_gbl_ctx.mctx, sizeof(*dataspace) * 2);
	if (dataspace == NULL) {
		log_error("Unable to allocate memory for fwd update");
		result = ISC_R_NOMEMORY; 
		goto cleanup;
	}

	ISC_LIST_INIT(updatelist);

	/*
	 * Construct the update list
	 * We always delete what's currently there
	 * Delete PTR RR.
	 */
	result = make_dns_dataset(dns_rdataclass_any, dns_rdatatype_ptr,
				  &dataspace[0], NULL, 0, 0);
	if (result != ISC_R_SUCCESS) {
		goto cleanup;
	}
	ISC_LIST_APPEND(uname->list, &dataspace[0].rdataset, link);

	/*
	 * If we are updating the pointer we then add the new one 
	 * Add PTR RR.
	 */
	if (ddns_cb->state == DDNS_STATE_ADD_PTR) {
#if 0
		/*
		 * I've left this dead code in the file  for now in case
		 * we decide to try and get rid of the ns_name functions.
		 * sar
		 */

		/*
		 * Need to convert pointer into on the wire representation
		 * We replace the '.' characters with the lengths of the
		 * next name and add a length to the beginning for the first
		 * name.
		 */
		if (ddns_cb->fwd_name.len == 1) {
			/* the root */
			buf[0] = 0;
			buflen = 1;
		} else {
			unsigned char *cp;
			buf[0] = '.';
			memcpy(&buf[1], ddns_cb->fwd_name.data,
			       ddns_cb->fwd_name.len);
			for(cp = buf + ddns_cb->fwd_name.len, buflen = 0;
			    cp != buf;
			    cp--) {
				if (*cp == '.') {
					*cp = buflen;
					buflen = 0;
				} else {
					buflen++;
				}
			}
			*cp = buflen;
			buflen = ddns_cb->fwd_name.len + 1;
		}
#endif
		/*
		 * Need to convert pointer into on the wire representation
		 */
		if (MRns_name_pton((char *)ddns_cb->fwd_name.data,
				   buf, 256) == -1) {
			goto cleanup;
		}
		buflen = 0;
		while (buf[buflen] != 0) {
			buflen += buf[buflen] + 1;
		}
		buflen++;

		result = make_dns_dataset(dns_rdataclass_in,
					  dns_rdatatype_ptr,
					  &dataspace[1],
					  buf, buflen, ddns_cb->ttl);
		if (result != ISC_R_SUCCESS) {
			goto cleanup;
		}
		ISC_LIST_APPEND(uname->list, &dataspace[1].rdataset, link);
	}

	ISC_LIST_APPEND(updatelist, uname, link);

	/*sar*/
	/*
	 * for now I'll cleanup the dataset immediately, it would be
	 * more efficient to keep it around in case the signaturure failed
	 * and we wanted to retry it.
	 */
	/* send the message, cleanup and return the result */
	result = ddns_update((dns_client_t *)dhcp_gbl_ctx.dnsclient,
			     dns_rdataclass_in, zname,
			     NULL, &updatelist,
			     zlist, tsec_key,
			     DNS_CLIENTRESOPT_ALLOWRUN,
			     dhcp_gbl_ctx.task,
			     ddns_interlude, (void *)ddns_cb,
			     &ddns_cb->transaction);
	if (result == ISC_R_FAMILYNOSUPPORT) {
		log_info("Unable to perform DDNS update, "
			 "address family not supported");
	}

#if defined (DEBUG_DNS_UPDATES)
	print_dns_status(DDNS_PRINT_OUTBOUND, ddns_cb, result);
#endif

 cleanup:
#if defined (DEBUG_DNS_UPDATES)
	if (result != ISC_R_SUCCESS) {
		log_info("DDNS: %s(%d): error in ddns_modify_ptr %s for %p",
			 file, line, isc_result_totext(result), ddns_cb);
	}
#endif

	if (dataspace != NULL) {
		isc_mem_put(dhcp_gbl_ctx.mctx, dataspace,
			    sizeof(*dataspace) * 2);
	}
	return(result);
}

void
ddns_cancel(dhcp_ddns_cb_t *ddns_cb, const char *file, int line) {
	ddns_cb->flags |= DDNS_ABORT;
	if (ddns_cb->transaction != NULL) {
		dns_client_cancelupdate((dns_clientupdatetrans_t *)
					ddns_cb->transaction);
	}
	ddns_cb->lease = NULL;

#if defined (DEBUG_DNS_UPDATES)
	log_info("DDNS: %s(%d): cancelling transaction for  %p",
		 file, line,  ddns_cb);
#endif
}

#endif /* NSUPDATE */

HASH_FUNCTIONS (dns_zone, const char *, struct dns_zone, dns_zone_hash_t,
		dns_zone_reference, dns_zone_dereference, do_case_hash)