/*
 * Copyright (C) Internet Systems Consortium, Inc. ("ISC")
 *
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, you can obtain one at https://mozilla.org/MPL/2.0/.
 *
 * See the COPYRIGHT file distributed with this work for additional
 * information regarding copyright ownership.
 */

#include <inttypes.h>
#include <stdbool.h>
#include <stdlib.h>

#include <isc/mem.h>
#include <isc/print.h>
#include <isc/region.h>
#include <isc/string.h>
#include <isc/util.h>

#include <dns/kasp.h>
#include <dns/keyvalues.h>
#include <dns/log.h>
#include <dns/result.h>
#include <dns/secalg.h>

#include <isccfg/cfg.h>
#include <isccfg/kaspconf.h>
#include <isccfg/namedconf.h>

#define DEFAULT_NSEC3PARAM_ITER	   5
#define DEFAULT_NSEC3PARAM_SALTLEN 8

/*
 * Utility function for getting a configuration option.
 */
static isc_result_t
confget(cfg_obj_t const *const *maps, const char *name, const cfg_obj_t **obj) {
	for (size_t i = 0;; i++) {
		if (maps[i] == NULL) {
			return (ISC_R_NOTFOUND);
		}
		if (cfg_map_get(maps[i], name, obj) == ISC_R_SUCCESS) {
			return (ISC_R_SUCCESS);
		}
	}
}

/*
 * Utility function for configuring durations.
 */
static uint32_t
get_duration(const cfg_obj_t **maps, const char *option, uint32_t dfl) {
	const cfg_obj_t *obj;
	isc_result_t result;
	obj = NULL;

	result = confget(maps, option, &obj);
	if (result == ISC_R_NOTFOUND) {
		return (dfl);
	}
	INSIST(result == ISC_R_SUCCESS);
	return (cfg_obj_asduration(obj));
}

/*
 * Create a new kasp key derived from configuration.
 */
static isc_result_t
cfg_kaspkey_fromconfig(const cfg_obj_t *config, dns_kasp_t *kasp,
		       isc_log_t *logctx) {
	isc_result_t result;
	dns_kasp_key_t *key = NULL;

	/* Create a new key reference. */
	result = dns_kasp_key_create(kasp, &key);
	if (result != ISC_R_SUCCESS) {
		return (result);
	}

	if (config == NULL) {
		/* We are creating a key reference for the default kasp. */
		key->role |= DNS_KASP_KEY_ROLE_KSK | DNS_KASP_KEY_ROLE_ZSK;
		key->lifetime = 0; /* unlimited */
		key->algorithm = DNS_KEYALG_ECDSA256;
		key->length = -1;
	} else {
		const char *rolestr = NULL;
		const cfg_obj_t *obj = NULL;
		isc_consttextregion_t alg;

		rolestr = cfg_obj_asstring(cfg_tuple_get(config, "role"));
		if (strcmp(rolestr, "ksk") == 0) {
			key->role |= DNS_KASP_KEY_ROLE_KSK;
		} else if (strcmp(rolestr, "zsk") == 0) {
			key->role |= DNS_KASP_KEY_ROLE_ZSK;
		} else if (strcmp(rolestr, "csk") == 0) {
			key->role |= DNS_KASP_KEY_ROLE_KSK;
			key->role |= DNS_KASP_KEY_ROLE_ZSK;
		}

		key->lifetime = 0; /* unlimited */
		obj = cfg_tuple_get(config, "lifetime");
		if (cfg_obj_isduration(obj)) {
			key->lifetime = cfg_obj_asduration(obj);
		}

		obj = cfg_tuple_get(config, "algorithm");
		alg.base = cfg_obj_asstring(obj);
		alg.length = strlen(alg.base);
		result = dns_secalg_fromtext(&key->algorithm,
					     (isc_textregion_t *)&alg);
		if (result != ISC_R_SUCCESS) {
			cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
				    "dnssec-policy: bad algorithm %s",
				    alg.base);
			result = DNS_R_BADALG;
			goto cleanup;
		}

		obj = cfg_tuple_get(config, "length");
		if (cfg_obj_isuint32(obj)) {
			uint32_t min, size;
			size = cfg_obj_asuint32(obj);

			switch (key->algorithm) {
			case DNS_KEYALG_RSASHA1:
			case DNS_KEYALG_NSEC3RSASHA1:
			case DNS_KEYALG_RSASHA256:
			case DNS_KEYALG_RSASHA512:
				min = DNS_KEYALG_RSASHA512 ? 1024 : 512;
				if (size < min || size > 4096) {
					cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
						    "dnssec-policy: key with "
						    "algorithm %s has invalid "
						    "key length %u",
						    alg.base, size);
					result = ISC_R_RANGE;
					goto cleanup;
				}
				break;
			case DNS_KEYALG_ECDSA256:
			case DNS_KEYALG_ECDSA384:
			case DNS_KEYALG_ED25519:
			case DNS_KEYALG_ED448:
				cfg_obj_log(obj, logctx, ISC_LOG_WARNING,
					    "dnssec-policy: key algorithm %s "
					    "has predefined length; ignoring "
					    "length value %u",
					    alg.base, size);
			default:
				break;
			}

			key->length = size;
		}
	}

	dns_kasp_addkey(kasp, key);
	return (ISC_R_SUCCESS);

cleanup:

	dns_kasp_key_destroy(key);
	return (result);
}

static isc_result_t
cfg_nsec3param_fromconfig(const cfg_obj_t *config, dns_kasp_t *kasp,
			  isc_log_t *logctx) {
	dns_kasp_key_t *kkey;
	unsigned int min_keysize = 4096;
	const cfg_obj_t *obj = NULL;
	uint32_t iter = DEFAULT_NSEC3PARAM_ITER;
	uint32_t saltlen = DEFAULT_NSEC3PARAM_SALTLEN;
	uint32_t badalg = 0;
	bool optout = false;
	isc_result_t ret = ISC_R_SUCCESS;

	/* How many iterations. */
	obj = cfg_tuple_get(config, "iterations");
	if (cfg_obj_isuint32(obj)) {
		iter = cfg_obj_asuint32(obj);
	}
	dns_kasp_freeze(kasp);
	for (kkey = ISC_LIST_HEAD(dns_kasp_keys(kasp)); kkey != NULL;
	     kkey = ISC_LIST_NEXT(kkey, link))
	{
		unsigned int keysize = dns_kasp_key_size(kkey);
		uint32_t keyalg = dns_kasp_key_algorithm(kkey);

		if (keysize < min_keysize) {
			min_keysize = keysize;
		}

		/* NSEC3 cannot be used with certain key algorithms. */
		if (keyalg == DNS_KEYALG_RSAMD5 || keyalg == DNS_KEYALG_DH ||
		    keyalg == DNS_KEYALG_DSA || keyalg == DNS_KEYALG_RSASHA1)
		{
			badalg = keyalg;
		}
	}
	dns_kasp_thaw(kasp);

	if (badalg > 0) {
		char algstr[DNS_SECALG_FORMATSIZE];
		dns_secalg_format((dns_secalg_t)badalg, algstr, sizeof(algstr));
		cfg_obj_log(
			obj, logctx, ISC_LOG_ERROR,
			"dnssec-policy: cannot use nsec3 with algorithm '%s'",
			algstr);
		return (DNS_R_NSEC3BADALG);
	}

	/* See RFC 5155 Section 10.3 for iteration limits. */
	if (min_keysize <= 1024 && iter > 150) {
		ret = DNS_R_NSEC3ITERRANGE;
	} else if (min_keysize <= 2048 && iter > 500) {
		ret = DNS_R_NSEC3ITERRANGE;
	} else if (min_keysize <= 4096 && iter > 2500) {
		ret = DNS_R_NSEC3ITERRANGE;
	}

	if (ret == DNS_R_NSEC3ITERRANGE) {
		cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
			    "dnssec-policy: nsec3 iterations value %u "
			    "out of range",
			    iter);
		return (ret);
	}

	/* Opt-out? */
	obj = cfg_tuple_get(config, "optout");
	if (cfg_obj_isboolean(obj)) {
		optout = cfg_obj_asboolean(obj);
	}

	/* Salt */
	obj = cfg_tuple_get(config, "salt-length");
	if (cfg_obj_isuint32(obj)) {
		saltlen = cfg_obj_asuint32(obj);
	}
	if (saltlen > 0xff) {
		cfg_obj_log(obj, logctx, ISC_LOG_ERROR,
			    "dnssec-policy: nsec3 salt length %u too high",
			    saltlen);
		return (DNS_R_NSEC3SALTRANGE);
	}

	dns_kasp_setnsec3param(kasp, iter, optout, saltlen);
	return (ISC_R_SUCCESS);
}

isc_result_t
cfg_kasp_fromconfig(const cfg_obj_t *config, const char *name, isc_mem_t *mctx,
		    isc_log_t *logctx, dns_kasplist_t *kasplist,
		    dns_kasp_t **kaspp) {
	isc_result_t result;
	const cfg_obj_t *maps[2];
	const cfg_obj_t *koptions = NULL;
	const cfg_obj_t *keys = NULL;
	const cfg_obj_t *nsec3 = NULL;
	const cfg_listelt_t *element = NULL;
	const char *kaspname = NULL;
	dns_kasp_t *kasp = NULL;
	int i = 0;

	REQUIRE(kaspp != NULL && *kaspp == NULL);

	kaspname = (name == NULL)
			   ? cfg_obj_asstring(cfg_tuple_get(config, "name"))
			   : name;
	INSIST(kaspname != NULL);

	result = dns_kasplist_find(kasplist, kaspname, &kasp);

	if (result == ISC_R_SUCCESS) {
		return (ISC_R_EXISTS);
	}
	if (result != ISC_R_NOTFOUND) {
		return (result);
	}

	/* No kasp with configured name was found in list, create new one. */
	INSIST(kasp == NULL);
	result = dns_kasp_create(mctx, kaspname, &kasp);
	if (result != ISC_R_SUCCESS) {
		return (result);
	}
	INSIST(kasp != NULL);

	/* Now configure. */
	INSIST(DNS_KASP_VALID(kasp));

	if (config != NULL) {
		koptions = cfg_tuple_get(config, "options");
		maps[i++] = koptions;
	}
	maps[i] = NULL;

	/* Configuration: Signatures */
	dns_kasp_setsigrefresh(kasp, get_duration(maps, "signatures-refresh",
						  DNS_KASP_SIG_REFRESH));
	dns_kasp_setsigvalidity(kasp, get_duration(maps, "signatures-validity",
						   DNS_KASP_SIG_VALIDITY));
	dns_kasp_setsigvalidity_dnskey(
		kasp, get_duration(maps, "signatures-validity-dnskey",
				   DNS_KASP_SIG_VALIDITY_DNSKEY));

	/* Configuration: Keys */
	dns_kasp_setdnskeyttl(
		kasp, get_duration(maps, "dnskey-ttl", DNS_KASP_KEY_TTL));
	dns_kasp_setpublishsafety(kasp, get_duration(maps, "publish-safety",
						     DNS_KASP_PUBLISH_SAFETY));
	dns_kasp_setretiresafety(kasp, get_duration(maps, "retire-safety",
						    DNS_KASP_RETIRE_SAFETY));
	dns_kasp_setpurgekeys(
		kasp, get_duration(maps, "purge-keys", DNS_KASP_PURGE_KEYS));

	(void)confget(maps, "keys", &keys);
	if (keys != NULL) {
		for (element = cfg_list_first(keys); element != NULL;
		     element = cfg_list_next(element))
		{
			cfg_obj_t *kobj = cfg_listelt_value(element);
			result = cfg_kaspkey_fromconfig(kobj, kasp, logctx);
			if (result != ISC_R_SUCCESS) {
				goto cleanup;
			}
		}
		INSIST(!(dns_kasp_keylist_empty(kasp)));
	} else if (strcmp(kaspname, "none") == 0) {
		/* "dnssec-policy none": key list must be empty */
		INSIST(strcmp(kaspname, "none") == 0);
		INSIST(dns_kasp_keylist_empty(kasp));
	} else {
		/* No keys clause configured, use the "default". */
		result = cfg_kaspkey_fromconfig(NULL, kasp, logctx);
		if (result != ISC_R_SUCCESS) {
			goto cleanup;
		}
		INSIST(!(dns_kasp_keylist_empty(kasp)));
	}

	/* Configuration: NSEC3 */
	(void)confget(maps, "nsec3param", &nsec3);
	if (nsec3 == NULL) {
		dns_kasp_setnsec3(kasp, false);
	} else {
		dns_kasp_setnsec3(kasp, true);
		result = cfg_nsec3param_fromconfig(nsec3, kasp, logctx);
		if (result != ISC_R_SUCCESS) {
			goto cleanup;
		}
	}

	/* Configuration: Zone settings */
	dns_kasp_setzonemaxttl(
		kasp, get_duration(maps, "max-zone-ttl", DNS_KASP_ZONE_MAXTTL));
	dns_kasp_setzonepropagationdelay(
		kasp, get_duration(maps, "zone-propagation-delay",
				   DNS_KASP_ZONE_PROPDELAY));

	/* Configuration: Parent settings */
	dns_kasp_setdsttl(kasp,
			  get_duration(maps, "parent-ds-ttl", DNS_KASP_DS_TTL));
	dns_kasp_setparentpropagationdelay(
		kasp, get_duration(maps, "parent-propagation-delay",
				   DNS_KASP_PARENT_PROPDELAY));

	/* Append it to the list for future lookups. */
	ISC_LIST_APPEND(*kasplist, kasp, link);
	INSIST(!(ISC_LIST_EMPTY(*kasplist)));

	/* Success: Attach the kasp to the pointer and return. */
	dns_kasp_attach(kasp, kaspp);

	/* Don't detach as kasp is on '*kasplist' */
	return (ISC_R_SUCCESS);

cleanup:

	/* Something bad happened, detach (destroys kasp) and return error. */
	dns_kasp_detach(&kasp);
	return (result);
}
