check.c

/*
 * Copyright (C) 2004-2006  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 2001-2003  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.
 */

/* $Id: check.c,v 1.69 2006/02/17 00:24:20 marka Exp $ */

/*! \file */

#include <config.h>

#include <stdlib.h>
#include <string.h>

#include <isc/buffer.h>
#include <isc/log.h>
#include <isc/mem.h>
#include <isc/netaddr.h>
#include <isc/parseint.h>
#include <isc/region.h>
#include <isc/result.h>
#include <isc/sockaddr.h>
#include <isc/symtab.h>
#include <isc/util.h>

#include <dns/acl.h>
#include <dns/fixedname.h>
#include <dns/rdataclass.h>
#include <dns/rdatatype.h>
#include <dns/secalg.h>

#include <isccfg/aclconf.h>
#include <isccfg/cfg.h>

#include <bind9/check.h>

static void
freekey(char *key, unsigned int type, isc_symvalue_t value, void *userarg) {
	UNUSED(type);
	UNUSED(value);
	isc_mem_free(userarg, key);
}

static isc_result_t
check_orderent(cfg_obj_t *ent, isc_log_t *logctx) {
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;
	isc_textregion_t r;
	dns_fixedname_t fixed;
	cfg_obj_t *obj;
	dns_rdataclass_t rdclass;
	dns_rdatatype_t rdtype;
	isc_buffer_t b;
	const char *str;

	dns_fixedname_init(&fixed);
	obj = cfg_tuple_get(ent, "class");
	if (cfg_obj_isstring(obj)) {

		DE_CONST(cfg_obj_asstring(obj), r.base);
		r.length = strlen(r.base);
		tresult = dns_rdataclass_fromtext(&rdclass, &r);
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "rrset-order: invalid class '%s'",
				    r.base);
			result = ISC_R_FAILURE;
		}
	}

	obj = cfg_tuple_get(ent, "type");
	if (cfg_obj_isstring(obj)) {

		DE_CONST(cfg_obj_asstring(obj), r.base);
		r.length = strlen(r.base);
		tresult = dns_rdatatype_fromtext(&rdtype, &r);
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "rrset-order: invalid type '%s'",
				    r.base);
			result = ISC_R_FAILURE;
		}
	}

	obj = cfg_tuple_get(ent, "name");
	if (cfg_obj_isstring(obj)) {
		str = cfg_obj_asstring(obj);
		isc_buffer_init(&b, str, strlen(str));
		isc_buffer_add(&b, strlen(str));
		tresult = dns_name_fromtext(dns_fixedname_name(&fixed), &b,
					    dns_rootname, ISC_FALSE, NULL);
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "rrset-order: invalid name '%s'", str);
			result = ISC_R_FAILURE;
		}
	}

	obj = cfg_tuple_get(ent, "order");
	if (!cfg_obj_isstring(obj) ||
	    strcasecmp("order", cfg_obj_asstring(obj)) != 0) {
		cfg_obj_log(ent, logctx, ISC_LOG_ERROR,
			    "rrset-order: keyword 'order' missing");
		result = ISC_R_FAILURE;
	}

	obj = cfg_tuple_get(ent, "ordering");
	if (!cfg_obj_isstring(obj)) {
	    cfg_obj_log(ent, logctx, ISC_LOG_ERROR,
			"rrset-order: missing ordering");
		result = ISC_R_FAILURE;
	} else if (strcasecmp(cfg_obj_asstring(obj), "fixed") == 0) {
		cfg_obj_log(obj, logctx, ISC_LOG_WARNING,
			    "rrset-order: order 'fixed' not fully implemented");
	} else if (/* strcasecmp(cfg_obj_asstring(obj), "fixed") != 0 && */
		   strcasecmp(cfg_obj_asstring(obj), "random") != 0 &&
		   strcasecmp(cfg_obj_asstring(obj), "cyclic") != 0) {
		cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
			    "rrset-order: invalid order '%s'",
			    cfg_obj_asstring(obj));
		result = ISC_R_FAILURE;
	}
	return (result);
}

static isc_result_t
check_order(cfg_obj_t *options, isc_log_t *logctx) {
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;
	cfg_listelt_t *element;
	cfg_obj_t *obj = NULL;

	if (cfg_map_get(options, "rrset-order", &obj) != ISC_R_SUCCESS)
		return (result);

	for (element = cfg_list_first(obj);
	     element != NULL;
	     element = cfg_list_next(element))
	{
		tresult = check_orderent(cfg_listelt_value(element), logctx);
		if (tresult != ISC_R_SUCCESS)
			result = tresult;
	}
	return (result);
}

static isc_result_t
check_dual_stack(cfg_obj_t *options, isc_log_t *logctx) {
	cfg_listelt_t *element;
	cfg_obj_t *alternates = NULL;
	cfg_obj_t *value;
	cfg_obj_t *obj;
	const char *str;
	dns_fixedname_t fixed;
	dns_name_t *name;
	isc_buffer_t buffer;
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;

	(void)cfg_map_get(options, "dual-stack-servers", &alternates);

	if (alternates == NULL)
		return (ISC_R_SUCCESS);

	obj = cfg_tuple_get(alternates, "port");
	if (cfg_obj_isuint32(obj)) {
		isc_uint32_t val = cfg_obj_asuint32(obj);
		if (val > ISC_UINT16_MAX) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "port '%u' out of range", val);
			result = ISC_R_FAILURE;
		}
	}
	obj = cfg_tuple_get(alternates, "addresses");
	for (element = cfg_list_first(obj);
	     element != NULL;
	     element = cfg_list_next(element)) {
		value = cfg_listelt_value(element);
		if (cfg_obj_issockaddr(value))
			continue;
		obj = cfg_tuple_get(value, "name");
		str = cfg_obj_asstring(obj);
		isc_buffer_init(&buffer, str, strlen(str));
		isc_buffer_add(&buffer, strlen(str));
		dns_fixedname_init(&fixed);
		name = dns_fixedname_name(&fixed);
		tresult = dns_name_fromtext(name, &buffer, dns_rootname,
					   ISC_FALSE, NULL);
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "bad name '%s'", str);
			result = ISC_R_FAILURE;
		}
		obj = cfg_tuple_get(value, "port");
		if (cfg_obj_isuint32(obj)) {
			isc_uint32_t val = cfg_obj_asuint32(obj);
			if (val > ISC_UINT16_MAX) {
				cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
					    "port '%u' out of range", val);
				result = ISC_R_FAILURE;
			}
		}
	}
	return (result);
}

static isc_result_t
check_forward(cfg_obj_t *options, isc_log_t *logctx) {
	cfg_obj_t *forward = NULL;
	cfg_obj_t *forwarders = NULL;

	(void)cfg_map_get(options, "forward", &forward);
	(void)cfg_map_get(options, "forwarders", &forwarders);

	if (forward != NULL && forwarders == NULL) {
		cfg_obj_log(forward, logctx, ISC_LOG_ERROR,
			    "no matching 'forwarders' statement");
		return (ISC_R_FAILURE);
	}
	return (ISC_R_SUCCESS);
}

static isc_result_t
disabled_algorithms(cfg_obj_t *disabled, isc_log_t *logctx) {
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;
	cfg_listelt_t *element;
	const char *str;
	isc_buffer_t b;
	dns_fixedname_t fixed;
	dns_name_t *name;
	cfg_obj_t *obj;

	dns_fixedname_init(&fixed);
	name = dns_fixedname_name(&fixed);
	obj = cfg_tuple_get(disabled, "name");
	str = cfg_obj_asstring(obj);
	isc_buffer_init(&b, str, strlen(str));
	isc_buffer_add(&b, strlen(str));
	tresult = dns_name_fromtext(name, &b, dns_rootname, ISC_FALSE, NULL);
	if (tresult != ISC_R_SUCCESS) {
		cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
			    "bad domain name '%s'", str);
		result = tresult;
	}

	obj = cfg_tuple_get(disabled, "algorithms");

	for (element = cfg_list_first(obj);
	     element != NULL;
	     element = cfg_list_next(element))
	{
		isc_textregion_t r;
		dns_secalg_t alg;
		isc_result_t tresult;

		DE_CONST(cfg_obj_asstring(cfg_listelt_value(element)), r.base);
		r.length = strlen(r.base);

		tresult = dns_secalg_fromtext(&alg, &r);
		if (tresult != ISC_R_SUCCESS) {
			isc_uint8_t ui;
			result = isc_parse_uint8(&ui, r.base, 10);
		}
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(cfg_listelt_value(element), logctx,
				    ISC_LOG_ERROR, "invalid algorithm '%s'",
				    r.base);
			result = tresult;
		}
	}
	return (result);
}

static isc_result_t
nameexist(cfg_obj_t *obj, const char *name, int value, isc_symtab_t *symtab,
	  const char *fmt, isc_log_t *logctx, isc_mem_t *mctx)
{
	char *key;
	const char *file;
	unsigned int line;
	isc_result_t result;
	isc_symvalue_t symvalue;

	key = isc_mem_strdup(mctx, name);
	if (key == NULL)
		return (ISC_R_NOMEMORY);
	symvalue.as_pointer = obj;
	result = isc_symtab_define(symtab, key, value, symvalue,
				   isc_symexists_reject);
	if (result == ISC_R_EXISTS) {
		RUNTIME_CHECK(isc_symtab_lookup(symtab, key, value,
						&symvalue) == ISC_R_SUCCESS);
		file = cfg_obj_file(symvalue.as_pointer);
		line = cfg_obj_line(symvalue.as_pointer);

		if (file == NULL)
			file = "<unknown file>";
		cfg_obj_log(obj, logctx, ISC_LOG_ERROR, fmt, key, file, line);
		isc_mem_free(mctx, key);
		result = ISC_R_EXISTS;
	} else if (result != ISC_R_SUCCESS) {
		isc_mem_free(mctx, key);
	}
	return (result);
}

static isc_result_t
mustbesecure(cfg_obj_t *secure, isc_symtab_t *symtab, isc_log_t *logctx,
	     isc_mem_t *mctx)
{
	cfg_obj_t *obj;
	char namebuf[DNS_NAME_FORMATSIZE];
	const char *str;
	dns_fixedname_t fixed;
	dns_name_t *name;
	isc_buffer_t b;
	isc_result_t result = ISC_R_SUCCESS;

	dns_fixedname_init(&fixed);
	name = dns_fixedname_name(&fixed);
	obj = cfg_tuple_get(secure, "name");
	str = cfg_obj_asstring(obj);
	isc_buffer_init(&b, str, strlen(str));
	isc_buffer_add(&b, strlen(str));
	result = dns_name_fromtext(name, &b, dns_rootname, ISC_FALSE, NULL);
	if (result != ISC_R_SUCCESS) {
		cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
			    "bad domain name '%s'", str);
	} else {
		dns_name_format(name, namebuf, sizeof(namebuf));
		result = nameexist(secure, namebuf, 1, symtab,
				   "dnssec-must-be-secure '%s': already "
				   "exists previous definition: %s:%u",
				   logctx, mctx);
	}
	return (result);
}

static isc_result_t
checkacl(const char *aclname, cfg_aclconfctx_t *actx, cfg_obj_t *zconfig,
	 cfg_obj_t *voptions, cfg_obj_t *config, isc_log_t *logctx,
	 isc_mem_t *mctx)
{
	isc_result_t result;
	cfg_obj_t *aclobj = NULL;
	cfg_obj_t *options;
	dns_acl_t *acl = NULL;

	if (zconfig != NULL) {
		options = cfg_tuple_get(zconfig, "options");
		cfg_map_get(options, aclname, &aclobj);
	}
	if (voptions != NULL && aclobj == NULL)
		cfg_map_get(voptions, aclname, &aclobj);
	if (config != NULL && aclobj == NULL) {
		options = NULL;
		cfg_map_get(config, "options", &options);
		if (options != NULL)
			cfg_map_get(options, aclname, &aclobj);
	}
	if (aclobj == NULL)
		return (ISC_R_SUCCESS);
	result = cfg_acl_fromconfig(aclobj, config, logctx, actx, mctx, &acl);
	if (acl != NULL)
		dns_acl_detach(&acl);
	return (result);
}

static isc_result_t
check_viewacls(cfg_aclconfctx_t *actx, cfg_obj_t *voptions, cfg_obj_t *config,
	      isc_log_t *logctx, isc_mem_t *mctx)
{
	isc_result_t result = ISC_R_SUCCESS, tresult;
	int i = 0;
	
	static const char *acls[] = { "allow-query", "allow-query-cache",
		"allow-recursion", "blackhole", "match-clients",
		"match-destinations", "sortlist", NULL };

	while (acls[i] != NULL) {
		tresult = checkacl(acls[i++], actx, NULL, voptions, config,
				   logctx, mctx);
		if (tresult != ISC_R_SUCCESS)
			result = tresult;  
	}
	return (result);
}

typedef struct {
	const char *name;
	unsigned int scale;
	unsigned int max;
} intervaltable;

static isc_result_t
check_options(cfg_obj_t *options, isc_log_t *logctx, isc_mem_t *mctx) {
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;
	unsigned int i;
	cfg_obj_t *obj = NULL;
	cfg_listelt_t *element;
	isc_symtab_t *symtab = NULL;
	dns_fixedname_t fixed;
	const char *str;
	dns_name_t *name;
	isc_buffer_t b;

	static intervaltable intervals[] = {
	{ "cleaning-interval", 60, 28 * 24 * 60 },	/* 28 days */
	{ "heartbeat-interval", 60, 28 * 24 * 60 },	/* 28 days */
	{ "interface-interval", 60, 28 * 24 * 60 },	/* 28 days */
	{ "max-transfer-idle-in", 60, 28 * 24 * 60 },	/* 28 days */
	{ "max-transfer-idle-out", 60, 28 * 24 * 60 },	/* 28 days */
	{ "max-transfer-time-in", 60, 28 * 24 * 60 },	/* 28 days */
	{ "max-transfer-time-out", 60, 28 * 24 * 60 },	/* 28 days */
	{ "sig-validity-interval", 86400, 10 * 366 },	/* 10 years */
	{ "statistics-interval", 60, 28 * 24 * 60 },	/* 28 days */
	};

	/*
	 * Check that fields specified in units of time other than seconds
	 * have reasonable values.
	 */
	for (i = 0; i < sizeof(intervals) / sizeof(intervals[0]); i++) {
		isc_uint32_t val;
		obj = NULL;
		(void)cfg_map_get(options, intervals[i].name, &obj);
		if (obj == NULL)
			continue;
		val = cfg_obj_asuint32(obj);
		if (val > intervals[i].max) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "%s '%u' is out of range (0..%u)",
				    intervals[i].name, val,
				    intervals[i].max);
			result = ISC_R_RANGE;
		} else if (val > (ISC_UINT32_MAX / intervals[i].scale)) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "%s '%d' is out of range",
				    intervals[i].name, val);
			result = ISC_R_RANGE;
		}
	}
	obj = NULL;
	(void)cfg_map_get(options, "preferred-glue", &obj);
	if (obj != NULL) {
		const char *str;
                str = cfg_obj_asstring(obj);
                if (strcasecmp(str, "a") != 0 &&
		    strcasecmp(str, "aaaa") != 0 &&
		    strcasecmp(str, "none") != 0)
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "preferred-glue unexpected value '%s'",
				    str);
	}
	obj = NULL;
	(void)cfg_map_get(options, "root-delegation-only", &obj);
	if (obj != NULL) {
		if (!cfg_obj_isvoid(obj)) {
			cfg_listelt_t *element;
			cfg_obj_t *exclude;
			const char *str;
			dns_fixedname_t fixed;
			dns_name_t *name;
			isc_buffer_t b;

			dns_fixedname_init(&fixed);
			name = dns_fixedname_name(&fixed);
			for (element = cfg_list_first(obj);
			     element != NULL;
			     element = cfg_list_next(element)) {
				exclude = cfg_listelt_value(element);
				str = cfg_obj_asstring(exclude);
				isc_buffer_init(&b, str, strlen(str));
				isc_buffer_add(&b, strlen(str));
				tresult = dns_name_fromtext(name, &b,
							   dns_rootname,
                                                           ISC_FALSE, NULL);
				if (tresult != ISC_R_SUCCESS) {
					cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
						    "bad domain name '%s'",
						    str);
					result = tresult;
				}
			}
		}
	}
       
	/*
	 * Set supported DNSSEC algorithms.
	 */
	obj = NULL;
	(void)cfg_map_get(options, "disable-algorithms", &obj);
	if (obj != NULL) {
		for (element = cfg_list_first(obj);
		     element != NULL;
		     element = cfg_list_next(element))
		{
			obj = cfg_listelt_value(element);
			tresult = disabled_algorithms(obj, logctx);
			if (tresult != ISC_R_SUCCESS)
				result = tresult;
		}
	}

	dns_fixedname_init(&fixed);
	name = dns_fixedname_name(&fixed);

	/*
	 * Check the DLV zone name.
	 */
	obj = NULL;
	(void)cfg_map_get(options, "dnssec-lookaside", &obj);
	if (obj != NULL) {
		tresult = isc_symtab_create(mctx, 100, freekey, mctx,
					    ISC_TRUE, &symtab);
		if (tresult != ISC_R_SUCCESS)
			result = tresult;
		for (element = cfg_list_first(obj);
		     element != NULL;
		     element = cfg_list_next(element))
		{
			const char *dlv;

			obj = cfg_listelt_value(element);

			dlv = cfg_obj_asstring(cfg_tuple_get(obj, "domain"));
			isc_buffer_init(&b, dlv, strlen(dlv));
			isc_buffer_add(&b, strlen(dlv));
			tresult = dns_name_fromtext(name, &b, dns_rootname,
						    ISC_TRUE, NULL);
			if (tresult != ISC_R_SUCCESS) {
				cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
					    "bad domain name '%s'", dlv);
				result = tresult;
			}
			if (symtab != NULL) {
				tresult = nameexist(obj, dlv, 1, symtab,
						    "dnssec-lookaside '%s': "
						    "already exists previous "
						    "definition: %s:%u",
						    logctx, mctx);
				if (tresult != ISC_R_SUCCESS &&
				    result == ISC_R_SUCCESS)
					result = tresult;
			}
			/*
			 * XXXMPA to be removed when multiple lookaside
			 * namespaces are supported.
			 */
			if (!dns_name_equal(dns_rootname, name)) {
				cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
					    "dnssec-lookaside '%s': "
					    "non-root not yet supported", dlv);
				if (result == ISC_R_SUCCESS)
					result = ISC_R_FAILURE;
			}
			dlv = cfg_obj_asstring(cfg_tuple_get(obj,
					       "trust-anchor"));
			isc_buffer_init(&b, dlv, strlen(dlv));
			isc_buffer_add(&b, strlen(dlv));
			tresult = dns_name_fromtext(name, &b, dns_rootname,
						    ISC_TRUE, NULL);
			if (tresult != ISC_R_SUCCESS) {
				cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
					    "bad domain name '%s'", dlv);
				if (result == ISC_R_SUCCESS)
					result = tresult;
			}
		}
		if (symtab != NULL)
			isc_symtab_destroy(&symtab);
	}

	/*
	 * Check dnssec-must-be-secure.
	 */
	obj = NULL;
	(void)cfg_map_get(options, "dnssec-must-be-secure", &obj);
	if (obj != NULL) {
		isc_symtab_t *symtab = NULL;
		tresult = isc_symtab_create(mctx, 100, freekey, mctx,
					    ISC_FALSE, &symtab);
		if (tresult != ISC_R_SUCCESS)
			result = tresult;
		for (element = cfg_list_first(obj);
		     element != NULL;
		     element = cfg_list_next(element))
		{
			obj = cfg_listelt_value(element);
			tresult = mustbesecure(obj, symtab, logctx, mctx);
			if (tresult != ISC_R_SUCCESS)
				result = tresult;
		}
		if (symtab != NULL)
			isc_symtab_destroy(&symtab);
	}

	/*
	 * Check empty zone configuration.
	 */
	obj = NULL;
	(void)cfg_map_get(options, "empty-server", &obj);
	if (obj != NULL) {
		str = cfg_obj_asstring(obj);
		isc_buffer_init(&b, str, strlen(str));
		isc_buffer_add(&b, strlen(str));
		tresult = dns_name_fromtext(dns_fixedname_name(&fixed), &b,
					    dns_rootname, ISC_FALSE, NULL);
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "empty-server: invalid name '%s'", str);
			result = ISC_R_FAILURE;
		}
	}

	obj = NULL;
	(void)cfg_map_get(options, "empty-contact", &obj);
	if (obj != NULL) {
		str = cfg_obj_asstring(obj);
		isc_buffer_init(&b, str, strlen(str));
		isc_buffer_add(&b, strlen(str));
		tresult = dns_name_fromtext(dns_fixedname_name(&fixed), &b,
					    dns_rootname, ISC_FALSE, NULL);
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "empty-contact: invalid name '%s'", str);
			result = ISC_R_FAILURE;
		}
	}

	obj = NULL;
	(void)cfg_map_get(options, "disable-empty-zone", &obj);
	for (element = cfg_list_first(obj);
	     element != NULL;
	     element = cfg_list_next(element))
	{
		obj = cfg_listelt_value(element);
		str = cfg_obj_asstring(obj);
		isc_buffer_init(&b, str, strlen(str));
		isc_buffer_add(&b, strlen(str));
		tresult = dns_name_fromtext(dns_fixedname_name(&fixed), &b,
					    dns_rootname, ISC_FALSE, NULL);
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "disable-empty-zone: invalid name '%s'",
				    str);
			result = ISC_R_FAILURE;
		}
	}

	return (result);
}

static isc_result_t
get_masters_def(cfg_obj_t *cctx, const char *name, cfg_obj_t **ret) {
	isc_result_t result;
	cfg_obj_t *masters = NULL;
	cfg_listelt_t *elt;

	result = cfg_map_get(cctx, "masters", &masters);
	if (result != ISC_R_SUCCESS)
		return (result);
	for (elt = cfg_list_first(masters);
	     elt != NULL;
	     elt = cfg_list_next(elt)) {
		cfg_obj_t *list;
		const char *listname;

		list = cfg_listelt_value(elt);
		listname = cfg_obj_asstring(cfg_tuple_get(list, "name"));

		if (strcasecmp(listname, name) == 0) {
			*ret = list;
			return (ISC_R_SUCCESS);
		}
	}
	return (ISC_R_NOTFOUND);
}

static isc_result_t
validate_masters(cfg_obj_t *obj, cfg_obj_t *config, isc_uint32_t *countp,
		 isc_log_t *logctx, isc_mem_t *mctx)
{
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;
	isc_uint32_t count = 0;
	isc_symtab_t *symtab = NULL;
	isc_symvalue_t symvalue;
	cfg_listelt_t *element;
	cfg_listelt_t **stack = NULL;
	isc_uint32_t stackcount = 0, pushed = 0;
	cfg_obj_t *list;

	REQUIRE(countp != NULL);
	result = isc_symtab_create(mctx, 100, NULL, NULL, ISC_FALSE, &symtab);
	if (result != ISC_R_SUCCESS) {
		*countp = count;
		return (result);
	}

 newlist:
	list = cfg_tuple_get(obj, "addresses");
	element = cfg_list_first(list);
 resume:	
	for ( ;
	     element != NULL;
	     element = cfg_list_next(element))
	{
		const char *listname;
		cfg_obj_t *addr;
		cfg_obj_t *key;

		addr = cfg_tuple_get(cfg_listelt_value(element),
				     "masterselement");
		key = cfg_tuple_get(cfg_listelt_value(element), "key");

		if (cfg_obj_issockaddr(addr)) {
			count++;
			continue;
		}
		if (!cfg_obj_isvoid(key)) {
			cfg_obj_log(key, logctx, ISC_LOG_ERROR,
				    "unexpected token '%s'",
				    cfg_obj_asstring(key));
			if (result == ISC_R_SUCCESS)
				result = ISC_R_FAILURE;
		}
		listname = cfg_obj_asstring(addr);
		symvalue.as_pointer = addr;
		tresult = isc_symtab_define(symtab, listname, 1, symvalue,
					    isc_symexists_reject);
		if (tresult == ISC_R_EXISTS)
			continue;
		tresult = get_masters_def(config, listname, &obj);
		if (tresult != ISC_R_SUCCESS) {
			if (result == ISC_R_SUCCESS)
				result = tresult;
			cfg_obj_log(addr, logctx, ISC_LOG_ERROR,
				    "unable to find masters list '%s'",
				    listname);
			continue;
		}
		/* Grow stack? */
		if (stackcount == pushed) {
			void * new;
			isc_uint32_t newlen = stackcount + 16;
			size_t newsize, oldsize;

			newsize = newlen * sizeof(*stack);
			oldsize = stackcount * sizeof(*stack);
			new = isc_mem_get(mctx, newsize);
			if (new == NULL)
				goto cleanup;
			if (stackcount != 0) {
				memcpy(new, stack, oldsize);
				isc_mem_put(mctx, stack, oldsize);
			}
			stack = new;
			stackcount = newlen;
		}
		stack[pushed++] = cfg_list_next(element);
		goto newlist;
	}
	if (pushed != 0) {
		element = stack[--pushed];
		goto resume;
	}
 cleanup:
	if (stack != NULL)
		isc_mem_put(mctx, stack, stackcount * sizeof(*stack));
	isc_symtab_destroy(&symtab);
	*countp = count;
	return (result);
}

static isc_result_t
check_update_policy(cfg_obj_t *policy, isc_log_t *logctx) {
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;
	cfg_listelt_t *element;
	cfg_listelt_t *element2;
	dns_fixedname_t fixed;
	const char *str;
	isc_buffer_t b;

	for (element = cfg_list_first(policy);
	     element != NULL;
	     element = cfg_list_next(element))
	{
		cfg_obj_t *stmt = cfg_listelt_value(element);
		cfg_obj_t *identity = cfg_tuple_get(stmt, "identity");
		cfg_obj_t *matchtype = cfg_tuple_get(stmt, "matchtype");
		cfg_obj_t *dname = cfg_tuple_get(stmt, "name");
		cfg_obj_t *typelist = cfg_tuple_get(stmt, "types");

		dns_fixedname_init(&fixed);
		str = cfg_obj_asstring(identity);
		isc_buffer_init(&b, str, strlen(str));
		isc_buffer_add(&b, strlen(str));
		tresult = dns_name_fromtext(dns_fixedname_name(&fixed), &b,
                                            dns_rootname, ISC_FALSE, NULL);
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(identity, logctx, ISC_LOG_ERROR,
				    "'%s' is not a valid name", str);
			result = tresult;
		}
		if (tresult == ISC_R_SUCCESS &&
		    strcasecmp(cfg_obj_asstring(matchtype), "wildcard") == 0 &&
		    !dns_name_iswildcard(dns_fixedname_name(&fixed))) {
			cfg_obj_log(identity, logctx, ISC_LOG_ERROR,
				    "'%s' is not a wildcard", str);
			result = ISC_R_FAILURE;
		}

		dns_fixedname_init(&fixed);
		str = cfg_obj_asstring(dname);
		isc_buffer_init(&b, str, strlen(str));
		isc_buffer_add(&b, strlen(str));
		tresult = dns_name_fromtext(dns_fixedname_name(&fixed), &b,
					    dns_rootname, ISC_FALSE, NULL);
		if (tresult != ISC_R_SUCCESS) {
			cfg_obj_log(dname, logctx, ISC_LOG_ERROR,
				    "'%s' is not a valid name", str);
			result = tresult;
		}

		for (element2 = cfg_list_first(typelist);
		     element2 != NULL;
		     element2 = cfg_list_next(element2))
		{
			cfg_obj_t *typeobj;
			isc_textregion_t r;
			dns_rdatatype_t type;
			
			typeobj = cfg_listelt_value(element2);
			DE_CONST(cfg_obj_asstring(typeobj), r.base);
			r.length = strlen(r.base);

			tresult = dns_rdatatype_fromtext(&type, &r);
			if (tresult != ISC_R_SUCCESS) {
				cfg_obj_log(typeobj, logctx, ISC_LOG_ERROR,
                                            "'%s' is not a valid type", r.base);
				result = tresult;
			}
		}
	}
	return (result);
}

#define MASTERZONE	1
#define SLAVEZONE	2
#define STUBZONE	4
#define HINTZONE	8
#define FORWARDZONE	16
#define DELEGATIONZONE	32
#define CHECKACL	64

typedef struct {
	const char *name;
	int allowed;
} optionstable;

static isc_result_t
check_zoneconf(cfg_obj_t *zconfig, cfg_obj_t *voptions, cfg_obj_t *config,
	       isc_symtab_t *symtab, dns_rdataclass_t defclass,
	       cfg_aclconfctx_t *actx, isc_log_t *logctx, isc_mem_t *mctx)
{
	const char *zname;
	const char *typestr;
	unsigned int ztype;
	cfg_obj_t *zoptions;
	cfg_obj_t *obj = NULL;
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;
	unsigned int i;
	dns_rdataclass_t zclass;
	dns_fixedname_t fixedname;
	isc_buffer_t b;

	static optionstable options[] = {
	{ "allow-query", MASTERZONE | SLAVEZONE | STUBZONE | CHECKACL },
	{ "allow-notify", SLAVEZONE | CHECKACL },
	{ "allow-transfer", MASTERZONE | SLAVEZONE | CHECKACL },
	{ "notify", MASTERZONE | SLAVEZONE },
	{ "also-notify", MASTERZONE | SLAVEZONE },
	{ "dialup", MASTERZONE | SLAVEZONE | STUBZONE },
	{ "delegation-only", HINTZONE | STUBZONE },
	{ "forward", MASTERZONE | SLAVEZONE | STUBZONE | FORWARDZONE},
	{ "forwarders", MASTERZONE | SLAVEZONE | STUBZONE | FORWARDZONE},
	{ "maintain-ixfr-base", MASTERZONE | SLAVEZONE },
	{ "max-ixfr-log-size", MASTERZONE | SLAVEZONE },
	{ "notify-source", MASTERZONE | SLAVEZONE },
	{ "notify-source-v6", MASTERZONE | SLAVEZONE },
	{ "transfer-source", SLAVEZONE | STUBZONE },
	{ "transfer-source-v6", SLAVEZONE | STUBZONE },
	{ "max-transfer-time-in", SLAVEZONE | STUBZONE },
	{ "max-transfer-time-out", MASTERZONE | SLAVEZONE },
	{ "max-transfer-idle-in", SLAVEZONE | STUBZONE },
	{ "max-transfer-idle-out", MASTERZONE | SLAVEZONE },
	{ "max-retry-time", SLAVEZONE | STUBZONE },
	{ "min-retry-time", SLAVEZONE | STUBZONE },
	{ "max-refresh-time", SLAVEZONE | STUBZONE },
	{ "min-refresh-time", SLAVEZONE | STUBZONE },
	{ "sig-validity-interval", MASTERZONE },
	{ "zone-statistics", MASTERZONE | SLAVEZONE | STUBZONE },
	{ "allow-update", MASTERZONE | CHECKACL },
	{ "allow-update-forwarding", SLAVEZONE | CHECKACL },
	{ "file", MASTERZONE | SLAVEZONE | STUBZONE | HINTZONE },
	{ "journal", MASTERZONE | SLAVEZONE },
	{ "ixfr-base", MASTERZONE | SLAVEZONE },
	{ "ixfr-tmp-file", MASTERZONE | SLAVEZONE },
	{ "masters", SLAVEZONE | STUBZONE },
	{ "pubkey", MASTERZONE | SLAVEZONE | STUBZONE },
	{ "update-policy", MASTERZONE },
	{ "database", MASTERZONE | SLAVEZONE | STUBZONE },
	{ "key-directory", MASTERZONE },
	{ "check-wildcard", MASTERZONE },
	{ "check-mx", MASTERZONE },
	{ "integrity-check", MASTERZONE },
	{ "check-mx-cname", MASTERZONE },
	{ "check-srv-cname", MASTERZONE },
	{ "masterfile-format", MASTERZONE | SLAVEZONE | STUBZONE | HINTZONE },
	};

	static optionstable dialups[] = {
	{ "notify", MASTERZONE | SLAVEZONE },
	{ "notify-passive", SLAVEZONE },
	{ "refresh", SLAVEZONE | STUBZONE },
	{ "passive", SLAVEZONE | STUBZONE },
	};

	zname = cfg_obj_asstring(cfg_tuple_get(zconfig, "name"));

	zoptions = cfg_tuple_get(zconfig, "options");

	obj = NULL;
	(void)cfg_map_get(zoptions, "type", &obj);
	if (obj == NULL) {
		cfg_obj_log(zconfig, logctx, ISC_LOG_ERROR,
			    "zone '%s': type not present", zname);
		return (ISC_R_FAILURE);
	}

	typestr = cfg_obj_asstring(obj);
	if (strcasecmp(typestr, "master") == 0)
		ztype = MASTERZONE;
	else if (strcasecmp(typestr, "slave") == 0)
		ztype = SLAVEZONE;
	else if (strcasecmp(typestr, "stub") == 0)
		ztype = STUBZONE;
	else if (strcasecmp(typestr, "forward") == 0)
		ztype = FORWARDZONE;
	else if (strcasecmp(typestr, "hint") == 0)
		ztype = HINTZONE;
	else if (strcasecmp(typestr, "delegation-only") == 0)
		ztype = DELEGATIONZONE;
	else {
		cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
			    "zone '%s': invalid type %s",
			    zname, typestr);
		return (ISC_R_FAILURE);
	}

	obj = cfg_tuple_get(zconfig, "class");
	if (cfg_obj_isstring(obj)) {
		isc_textregion_t r;

		DE_CONST(cfg_obj_asstring(obj), r.base);
		r.length = strlen(r.base);
		result = dns_rdataclass_fromtext(&zclass, &r);
		if (result != ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "zone '%s': invalid class %s",
				    zname, r.base);
			return (ISC_R_FAILURE);
		}
		if (zclass != defclass) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "zone '%s': class '%s' does not "
				    "match view/default class",
				    zname, r.base);
			return (ISC_R_FAILURE);
		}
	}

	/*
	 * Look for an already existing zone.
	 * We need to make this cannonical as isc_symtab_define()
	 * deals with strings.
	 */
	dns_fixedname_init(&fixedname);
	isc_buffer_init(&b, zname, strlen(zname));
	isc_buffer_add(&b, strlen(zname));
	tresult = dns_name_fromtext(dns_fixedname_name(&fixedname), &b,
				   dns_rootname, ISC_TRUE, NULL);
	if (result != ISC_R_SUCCESS) {
		cfg_obj_log(zconfig, logctx, ISC_LOG_ERROR,
			    "zone '%s': is not a valid name", zname);
		tresult = ISC_R_FAILURE;
	} else {
		char namebuf[DNS_NAME_FORMATSIZE];

		dns_name_format(dns_fixedname_name(&fixedname),
				namebuf, sizeof(namebuf));
		tresult = nameexist(zconfig, namebuf, ztype == HINTZONE ? 1 : 2,
				   symtab, "zone '%s': already exists "
				   "previous definition: %s:%u", logctx, mctx);
		if (tresult != ISC_R_SUCCESS)
			result = tresult;
	}

	/*
	 * Look for inappropriate options for the given zone type.
	 * Check that ACLs expand correctly.
	 */
	for (i = 0; i < sizeof(options) / sizeof(options[0]); i++) {
		obj = NULL;
		if ((options[i].allowed & ztype) == 0 &&
		    cfg_map_get(zoptions, options[i].name, &obj) ==
		    ISC_R_SUCCESS)
		{
			if (strcmp(options[i].name, "allow-update") != 0 ||
			    ztype != SLAVEZONE) {
				cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
					    "option '%s' is not allowed "
					    "in '%s' zone '%s'",
					    options[i].name, typestr, zname);
					result = ISC_R_FAILURE;
			} else
				cfg_obj_log(obj, logctx, ISC_LOG_WARNING,
					    "option '%s' is not allowed "
					    "in '%s' zone '%s'",
					    options[i].name, typestr, zname);
		}
		obj = NULL;
		if ((options[i].allowed & ztype) != 0 &&
		    (options[i].allowed & CHECKACL) != 0) {

			tresult = checkacl(options[i].name, actx, zconfig,
				           voptions, config, logctx, mctx);
			if (tresult != ISC_R_SUCCESS)
				result = tresult;
		}

	}

	/*
	 * Slave & stub zones must have a "masters" field.
	 */
	if (ztype == SLAVEZONE || ztype == STUBZONE) {
		obj = NULL;
		if (cfg_map_get(zoptions, "masters", &obj) != ISC_R_SUCCESS) {
			cfg_obj_log(zoptions, logctx, ISC_LOG_ERROR,
				    "zone '%s': missing 'masters' entry",
				    zname);
			result = ISC_R_FAILURE;
		} else {
			isc_uint32_t count;
			tresult = validate_masters(obj, config, &count,
						   logctx, mctx);
			if (tresult != ISC_R_SUCCESS && result == ISC_R_SUCCESS)
				result = tresult;
			if (tresult == ISC_R_SUCCESS && count == 0) {
				cfg_obj_log(zoptions, logctx, ISC_LOG_ERROR,
					    "zone '%s': empty 'masters' entry",
					    zname);
				result = ISC_R_FAILURE;
			}
		}
	}

	/*
	 * Master zones can't have both "allow-update" and "update-policy".
	 */
	if (ztype == MASTERZONE) {
		isc_result_t res1, res2;
		obj = NULL;
		res1 = cfg_map_get(zoptions, "allow-update", &obj);
		obj = NULL;
		res2 = cfg_map_get(zoptions, "update-policy", &obj);
		if (res1 == ISC_R_SUCCESS && res2 == ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "zone '%s': 'allow-update' is ignored "
				    "when 'update-policy' is present",
				    zname);
			result = ISC_R_FAILURE;
		} else if (res2 == ISC_R_SUCCESS &&
			   check_update_policy(obj, logctx) != ISC_R_SUCCESS)
			result = ISC_R_FAILURE;
	}

	/*
	 * Check the excessively complicated "dialup" option.
	 */
	if (ztype == MASTERZONE || ztype == SLAVEZONE || ztype == STUBZONE) {
		cfg_obj_t *dialup = NULL;
		(void)cfg_map_get(zoptions, "dialup", &dialup);
		if (dialup != NULL && cfg_obj_isstring(dialup)) {
			const char *str = cfg_obj_asstring(dialup);
			for (i = 0;
			     i < sizeof(dialups) / sizeof(dialups[0]);
			     i++)
			{
				if (strcasecmp(dialups[i].name, str) != 0)
					continue;
				if ((dialups[i].allowed & ztype) == 0) {
					cfg_obj_log(obj, logctx,
						    ISC_LOG_ERROR,
						    "dialup type '%s' is not "
						    "allowed in '%s' "
						    "zone '%s'",
						    str, typestr, zname);
					result = ISC_R_FAILURE;
				}
				break;
			}
			if (i == sizeof(dialups) / sizeof(dialups[0])) {
				cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
					    "invalid dialup type '%s' in zone "
					    "'%s'", str, zname);
				result = ISC_R_FAILURE;
			}
		}
	}

	/*
	 * Check that forwarding is reasonable.
	 */
	if (check_forward(zoptions, logctx) != ISC_R_SUCCESS)
		result = ISC_R_FAILURE;

	/*
	 * Check various options.
	 */
	tresult = check_options(zoptions, logctx, mctx);
	if (tresult != ISC_R_SUCCESS)
		result = tresult;

	/*
	 * If the zone type is rbt/rbt64 then master/hint zones
	 * require file clauses.
	 */
	obj = NULL;
	tresult = cfg_map_get(zoptions, "database", &obj);
	if (tresult == ISC_R_NOTFOUND ||
	    (tresult == ISC_R_SUCCESS &&
	     (strcmp("rbt", cfg_obj_asstring(obj)) == 0 ||
	      strcmp("rbt64", cfg_obj_asstring(obj)) == 0))) {
		obj = NULL;
		tresult = cfg_map_get(zoptions, "file", &obj);
		if (tresult != ISC_R_SUCCESS &&
		    (ztype == MASTERZONE || ztype == HINTZONE)) {
			cfg_obj_log(zconfig, logctx, ISC_LOG_ERROR,
				    "zone '%s': missing 'file' entry",
				    zname);
			result = tresult;
		}
	}
	
	return (result);
}


typedef struct keyalgorithms {
	const char *name;
	isc_uint16_t size;
} algorithmtable;

isc_result_t
bind9_check_key(cfg_obj_t *key, isc_log_t *logctx) {
	cfg_obj_t *algobj = NULL;
	cfg_obj_t *secretobj = NULL;
	const char *keyname = cfg_obj_asstring(cfg_map_getname(key));
	const char *algorithm;
	int i;
	size_t len = 0;
	static const algorithmtable algorithms[] = {
		{ "hmac-md5", 128 },
		{ "hmac-md5.sig-alg.reg.int", 0 },
		{ "hmac-md5.sig-alg.reg.int.", 0 },
		{ "hmac-sha1", 160 },
		{ "hmac-sha224", 224 },
		{ "hmac-sha256", 256 },
		{ "hmac-sha384", 384 },
		{ "hmac-sha512", 512 },
		{  NULL, 0 }
	};
	
	(void)cfg_map_get(key, "algorithm", &algobj);
	(void)cfg_map_get(key, "secret", &secretobj);
	if (secretobj == NULL || algobj == NULL) {
		cfg_obj_log(key, logctx, ISC_LOG_ERROR,
			    "key '%s' must have both 'secret' and "
			    "'algorithm' defined",
			    keyname);
		return (ISC_R_FAILURE);
	}

	algorithm = cfg_obj_asstring(algobj);
	for (i = 0; algorithms[i].name != NULL; i++) {
		len = strlen(algorithms[i].name);
		if (strncasecmp(algorithms[i].name, algorithm, len) == 0 &&
		    (algorithm[len] == '\0' ||
		     (algorithms[i].size != 0 && algorithm[len] == '-')))
			break;
	}
	if (algorithms[i].name == NULL) {
		cfg_obj_log(algobj, logctx, ISC_LOG_ERROR,
			    "unknown algorithm '%s'", algorithm);
		return (ISC_R_NOTFOUND);
	}
	if (algorithm[len] == '-') {
		isc_uint16_t digestbits;
		isc_result_t result;
		result = isc_parse_uint16(&digestbits, algorithm + len + 1, 10);
		if (result == ISC_R_SUCCESS || result == ISC_R_RANGE) {
			if (result == ISC_R_RANGE ||
			    digestbits > algorithms[i].size) {
				cfg_obj_log(algobj, logctx, ISC_LOG_ERROR,
					    "key '%s' digest-bits too large "
					    "[%u..%u]", keyname,
					    algorithms[i].size / 2,
					    algorithms[i].size);
				return (ISC_R_RANGE);
			}
			if ((digestbits % 8) != 0) {
				cfg_obj_log(algobj, logctx, ISC_LOG_ERROR,
					    "key '%s' digest-bits not multiple"
					    " of 8", keyname);
				return (ISC_R_RANGE);
			}
			/*
			 * Recommended minima for hmac algorithms.
			 */
			if ((digestbits < (algorithms[i].size / 2U) ||
			     (digestbits < 80U)))
				cfg_obj_log(algobj, logctx, ISC_LOG_WARNING,
					    "key '%s' digest-bits too small "
					    "[<%u]", keyname, 
					    algorithms[i].size/2);
		} else {
			cfg_obj_log(algobj, logctx, ISC_LOG_ERROR,
				    "key '%s': unable to parse digest-bits",
				    keyname);
			return (result);
		}
	}
	return (ISC_R_SUCCESS);
}

static isc_result_t
check_keylist(cfg_obj_t *keys, isc_symtab_t *symtab, isc_log_t *logctx) {
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;
	cfg_listelt_t *element;

	for (element = cfg_list_first(keys);
	     element != NULL;
	     element = cfg_list_next(element))
	{
		cfg_obj_t *key = cfg_listelt_value(element);
		const char *keyname = cfg_obj_asstring(cfg_map_getname(key));
		isc_symvalue_t symvalue;

		tresult = bind9_check_key(key, logctx);
		if (tresult != ISC_R_SUCCESS)
			return (tresult);

		symvalue.as_pointer = key;
		tresult = isc_symtab_define(symtab, keyname, 1,
					    symvalue, isc_symexists_reject);
		if (tresult == ISC_R_EXISTS) {
			const char *file;
			unsigned int line;

			RUNTIME_CHECK(isc_symtab_lookup(symtab, keyname,
					    1, &symvalue) == ISC_R_SUCCESS);
			file = cfg_obj_file(symvalue.as_pointer);
			line = cfg_obj_line(symvalue.as_pointer);

			if (file == NULL)
				file = "<unknown file>";
			cfg_obj_log(key, logctx, ISC_LOG_ERROR,
				    "key '%s': already exists "
				    "previous definition: %s:%u",
				    keyname, file, line);
			result = tresult;
		} else if (tresult != ISC_R_SUCCESS)
			return (tresult);
	}
	return (result);
}

static struct {
	const char *v4;
	const char *v6;
} sources[] = {
	{ "transfer-source", "transfer-source-v6" },
	{ "notify-source", "notify-source-v6" },
	{ "query-source", "query-source-v6" },
	{ NULL, NULL }
};

static isc_result_t
check_servers(cfg_obj_t *servers, isc_log_t *logctx) {
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t tresult;
	cfg_listelt_t *e1, *e2;
	cfg_obj_t *v1, *v2;
	isc_netaddr_t n1, n2;
	unsigned int p1, p2;
	cfg_obj_t *obj;
	char buf[ISC_NETADDR_FORMATSIZE];
	const char *xfr;
	int source;

	for (e1 = cfg_list_first(servers); e1 != NULL; e1 = cfg_list_next(e1)) {
		v1 = cfg_listelt_value(e1);
		cfg_obj_asnetprefix(cfg_map_getname(v1), &n1, &p1);
		/*
		 * Check that unused bits are zero.
		 */