/*
 * Copyright (C) 2014-2018  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 http://mozilla.org/MPL/2.0/.
 */

/*! \file */

#include <config.h>

#include <isc/buffer.h>
#include <isc/log.h>
#include <isc/mem.h>
#include <isc/print.h>
#include <isc/rwlock.h>
#include <isc/string.h>
#include <isc/task.h>
#include <isc/time.h>
#include <isc/timer.h>
#include <isc/util.h>

#include <dns/db.h>
#include <dns/log.h>
#include <dns/nta.h>
#include <dns/fixedname.h>
#include <dns/name.h>
#include <dns/rbt.h>
#include <dns/rdataset.h>
#include <dns/resolver.h>
#include <dns/result.h>
#include <dns/time.h>

struct dns_nta {
	unsigned int		magic;
	isc_refcount_t		refcount;
	dns_ntatable_t		*ntatable;
	isc_boolean_t		forced;
	isc_timer_t		*timer;
	dns_fetch_t		*fetch;
	dns_rdataset_t		rdataset;
	dns_rdataset_t		sigrdataset;
	dns_fixedname_t		fn;
	dns_name_t		*name;
	isc_stdtime_t		expiry;
};

#define NTA_MAGIC		ISC_MAGIC('N', 'T', 'A', 'n')
#define VALID_NTA(nn)	 	ISC_MAGIC_VALID(nn, NTA_MAGIC)

/*
 * Obtain a reference to the nta object.  Released by
 * nta_detach.
 */
static void
nta_ref(dns_nta_t *nta) {
	isc_refcount_increment(&nta->refcount, NULL);
}

static void
nta_detach(isc_mem_t *mctx, dns_nta_t **ntap) {
	unsigned int refs;
	dns_nta_t *nta = *ntap;

	REQUIRE(VALID_NTA(nta));

	*ntap = NULL;
	isc_refcount_decrement(&nta->refcount, &refs);
	if (refs == 0) {
		nta->magic = 0;
		if (nta->timer != NULL) {
			(void) isc_timer_reset(nta->timer,
					       isc_timertype_inactive,
					       NULL, NULL, ISC_TRUE);
			isc_timer_detach(&nta->timer);
		}
		isc_refcount_destroy(&nta->refcount);
		if (dns_rdataset_isassociated(&nta->rdataset))
			dns_rdataset_disassociate(&nta->rdataset);
		if (dns_rdataset_isassociated(&nta->sigrdataset))
			dns_rdataset_disassociate(&nta->sigrdataset);
		if (nta->fetch != NULL) {
			dns_resolver_cancelfetch(nta->fetch);
			dns_resolver_destroyfetch(&nta->fetch);
		}
		isc_mem_put(mctx, nta, sizeof(dns_nta_t));
	}
}

static void
free_nta(void *data, void *arg) {
	dns_nta_t *nta = (dns_nta_t *) data;
	isc_mem_t *mctx = (isc_mem_t *) arg;

	nta_detach(mctx, &nta);
}

isc_result_t
dns_ntatable_create(dns_view_t *view,
		    isc_taskmgr_t *taskmgr, isc_timermgr_t *timermgr,
		    dns_ntatable_t **ntatablep)
{
	dns_ntatable_t *ntatable;
	isc_result_t result;

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

	ntatable = isc_mem_get(view->mctx, sizeof(*ntatable));
	if (ntatable == NULL)
		return (ISC_R_NOMEMORY);

	ntatable->task = NULL;
	result = isc_task_create(taskmgr, 0, &ntatable->task);
	if (result != ISC_R_SUCCESS)
		goto cleanup_ntatable;
	isc_task_setname(ntatable->task, "ntatable", ntatable);

	ntatable->table = NULL;
	result = dns_rbt_create(view->mctx, free_nta, view->mctx,
				&ntatable->table);
	if (result != ISC_R_SUCCESS)
		goto cleanup_task;

	result = isc_rwlock_init(&ntatable->rwlock, 0, 0);
	if (result != ISC_R_SUCCESS)
		goto cleanup_rbt;

	ntatable->timermgr = timermgr;
	ntatable->taskmgr = taskmgr;

	ntatable->view = view;
	ntatable->references = 1;

	ntatable->magic = NTATABLE_MAGIC;
	*ntatablep = ntatable;

	return (ISC_R_SUCCESS);

   cleanup_rbt:
	dns_rbt_destroy(&ntatable->table);

   cleanup_task:
	isc_task_detach(&ntatable->task);

   cleanup_ntatable:
	isc_mem_put(ntatable->view->mctx, ntatable, sizeof(*ntatable));

	return (result);
}

void
dns_ntatable_attach(dns_ntatable_t *source, dns_ntatable_t **targetp) {
	REQUIRE(VALID_NTATABLE(source));
	REQUIRE(targetp != NULL && *targetp == NULL);

	RWLOCK(&source->rwlock, isc_rwlocktype_write);

	INSIST(source->references > 0);
	source->references++;
	INSIST(source->references != 0);

	RWUNLOCK(&source->rwlock, isc_rwlocktype_write);

	*targetp = source;
}

void
dns_ntatable_detach(dns_ntatable_t **ntatablep) {
	isc_boolean_t destroy = ISC_FALSE;
	dns_ntatable_t *ntatable;

	REQUIRE(ntatablep != NULL && VALID_NTATABLE(*ntatablep));

	ntatable = *ntatablep;
	*ntatablep = NULL;

	RWLOCK(&ntatable->rwlock, isc_rwlocktype_write);
	INSIST(ntatable->references > 0);
	ntatable->references--;
	if (ntatable->references == 0)
		destroy = ISC_TRUE;
	RWUNLOCK(&ntatable->rwlock, isc_rwlocktype_write);

	if (destroy) {
		dns_rbt_destroy(&ntatable->table);
		isc_rwlock_destroy(&ntatable->rwlock);
		if (ntatable->task != NULL)
			isc_task_detach(&ntatable->task);
		ntatable->timermgr = NULL;
		ntatable->taskmgr = NULL;
		ntatable->magic = 0;
		isc_mem_put(ntatable->view->mctx, ntatable, sizeof(*ntatable));
	}
}

static void
fetch_done(isc_task_t *task, isc_event_t *event) {
	dns_fetchevent_t *devent = (dns_fetchevent_t *)event;
	dns_nta_t *nta = devent->ev_arg;
	isc_result_t eresult = devent->result;
	dns_ntatable_t *ntatable = nta->ntatable;
	dns_view_t *view = ntatable->view;
	isc_stdtime_t now;

	UNUSED(task);

	if (dns_rdataset_isassociated(&nta->rdataset))
		dns_rdataset_disassociate(&nta->rdataset);
	if (dns_rdataset_isassociated(&nta->sigrdataset))
		dns_rdataset_disassociate(&nta->sigrdataset);
	if (nta->fetch == devent->fetch)
		nta->fetch = NULL;
	dns_resolver_destroyfetch(&devent->fetch);

	if (devent->node != NULL)
		dns_db_detachnode(devent->db, &devent->node);
	if (devent->db != NULL)
		dns_db_detach(&devent->db);

	isc_event_free(&event);
	isc_stdtime_get(&now);

	switch (eresult) {
	case ISC_R_SUCCESS:
	case DNS_R_NCACHENXDOMAIN:
	case DNS_R_NXDOMAIN:
	case DNS_R_NCACHENXRRSET:
	case DNS_R_NXRRSET:
		if (nta->expiry > now)
			nta->expiry = now;
		break;
	default:
		break;
	}

	/*
	 * If we're expiring before the next recheck, we might
	 * as well stop the timer now.
	 */
	if (nta->timer != NULL && nta->expiry - now < view->nta_recheck)
		(void) isc_timer_reset(nta->timer, isc_timertype_inactive,
				       NULL, NULL, ISC_TRUE);
	nta_detach(view->mctx, &nta);
}

static void
checkbogus(isc_task_t *task, isc_event_t *event) {
	dns_nta_t *nta = event->ev_arg;
	dns_ntatable_t *ntatable = nta->ntatable;
	dns_view_t *view = ntatable->view;
	isc_result_t result;

	if (nta->fetch != NULL) {
		dns_resolver_cancelfetch(nta->fetch);
		nta->fetch = NULL;
	}
	if (dns_rdataset_isassociated(&nta->rdataset))
		dns_rdataset_disassociate(&nta->rdataset);
	if (dns_rdataset_isassociated(&nta->sigrdataset))
		dns_rdataset_disassociate(&nta->sigrdataset);

	isc_event_free(&event);

	nta_ref(nta);
	result = dns_resolver_createfetch(view->resolver, nta->name,
					  dns_rdatatype_nsec,
					  NULL, NULL, NULL,
					  DNS_FETCHOPT_NONTA,
					  task, fetch_done, nta,
					  &nta->rdataset,
					  &nta->sigrdataset,
					  &nta->fetch);
	if (result != ISC_R_SUCCESS)
		nta_detach(view->mctx, &nta);
}

static isc_result_t
settimer(dns_ntatable_t *ntatable, dns_nta_t *nta, isc_uint32_t lifetime) {
	isc_result_t result;
	isc_interval_t interval;
	dns_view_t *view;

	REQUIRE(VALID_NTATABLE(ntatable));
	REQUIRE(VALID_NTA(nta));

	if (ntatable->timermgr == NULL)
		return (ISC_R_SUCCESS);

	view = ntatable->view;
	if (view->nta_recheck == 0 || lifetime <= view->nta_recheck)
		return (ISC_R_SUCCESS);

	isc_interval_set(&interval, view->nta_recheck, 0);
	result = isc_timer_create(ntatable->timermgr, isc_timertype_ticker,
				  NULL, &interval, ntatable->task,
				  checkbogus, nta, &nta->timer);
	return (result);
}

static isc_result_t
nta_create(dns_ntatable_t *ntatable, dns_name_t *name, dns_nta_t **target) {
	isc_result_t result;
	dns_nta_t *nta = NULL;
	dns_view_t *view;

	REQUIRE(VALID_NTATABLE(ntatable));
	REQUIRE(target != NULL && *target == NULL);

	view = ntatable->view;

	nta = isc_mem_get(view->mctx, sizeof(dns_nta_t));
	if (nta == NULL)
		return (ISC_R_NOMEMORY);

	nta->ntatable = ntatable;
	nta->expiry = 0;
	nta->timer = NULL;
	nta->fetch = NULL;
	dns_rdataset_init(&nta->rdataset);
	dns_rdataset_init(&nta->sigrdataset);

	result = isc_refcount_init(&nta->refcount, 1);
	if (result != ISC_R_SUCCESS) {
		isc_mem_put(view->mctx, nta, sizeof(dns_nta_t));
		return (result);
	}

	dns_fixedname_init(&nta->fn);
	nta->name = dns_fixedname_name(&nta->fn);
	dns_name_copy(name, nta->name, NULL);

	nta->magic = NTA_MAGIC;

	*target = nta;
	return (ISC_R_SUCCESS);
}

isc_result_t
dns_ntatable_add(dns_ntatable_t *ntatable, dns_name_t *name,
		 isc_boolean_t force, isc_stdtime_t now,
		 isc_uint32_t lifetime)
{
	isc_result_t result;
	dns_nta_t *nta = NULL;
	dns_rbtnode_t *node;
	dns_view_t *view;

	REQUIRE(VALID_NTATABLE(ntatable));

	view = ntatable->view;

	result = nta_create(ntatable, name, &nta);
	if (result != ISC_R_SUCCESS)
		return (result);

	nta->expiry = now + lifetime;
	nta->forced = force;

	RWLOCK(&ntatable->rwlock, isc_rwlocktype_write);

	node = NULL;
	result = dns_rbt_addnode(ntatable->table, name, &node);
	if (result == ISC_R_SUCCESS) {
		if (!force)
			(void)settimer(ntatable, nta, lifetime);
		node->data = nta;
		nta = NULL;
	} else if (result == ISC_R_EXISTS) {
		dns_nta_t *n = node->data;
		if (n == NULL) {
			if (!force)
				(void)settimer(ntatable, nta, lifetime);
			node->data = nta;
			nta = NULL;
		} else {
			n->expiry = nta->expiry;
			nta_detach(view->mctx, &nta);
		}
		result = ISC_R_SUCCESS;
	}

	RWUNLOCK(&ntatable->rwlock, isc_rwlocktype_write);

	if (nta != NULL)
		nta_detach(view->mctx, &nta);

	return (result);
}

/*
 * Caller must hold a write lock on rwlock.
 */
static isc_result_t
deletenode(dns_ntatable_t *ntatable, const dns_name_t *name) {
	isc_result_t result;
	dns_rbtnode_t *node = NULL;

	REQUIRE(VALID_NTATABLE(ntatable));
	REQUIRE(name != NULL);

	result = dns_rbt_findnode(ntatable->table, name, NULL, &node, NULL,
				  DNS_RBTFIND_NOOPTIONS, NULL, NULL);
	if (result == ISC_R_SUCCESS) {
		if (node->data != NULL)
			result = dns_rbt_deletenode(ntatable->table,
						    node, ISC_FALSE);
		else
			result = ISC_R_NOTFOUND;
	} else if (result == DNS_R_PARTIALMATCH)
		result = ISC_R_NOTFOUND;

	return (result);
}

isc_result_t
dns_ntatable_delete(dns_ntatable_t *ntatable, dns_name_t *name) {
	isc_result_t result;

	RWLOCK(&ntatable->rwlock, isc_rwlocktype_write);
	result = deletenode(ntatable, name);
	RWUNLOCK(&ntatable->rwlock, isc_rwlocktype_write);

	return (result);
}

isc_boolean_t
dns_ntatable_covered(dns_ntatable_t *ntatable, isc_stdtime_t now,
		     dns_name_t *name, dns_name_t *anchor)
{
	isc_result_t result;
	dns_fixedname_t fn;
	dns_rbtnode_t *node;
	dns_name_t *foundname;
	dns_nta_t *nta = NULL;
	isc_boolean_t answer = ISC_FALSE;
	isc_rwlocktype_t locktype = isc_rwlocktype_read;

	REQUIRE(ntatable == NULL || VALID_NTATABLE(ntatable));
	REQUIRE(dns_name_isabsolute(name));

	if (ntatable == NULL)
		return (ISC_FALSE);

	dns_fixedname_init(&fn);
	foundname = dns_fixedname_name(&fn);

 relock:
	RWLOCK(&ntatable->rwlock, locktype);
 again:
	node = NULL;
	result = dns_rbt_findnode(ntatable->table, name, foundname, &node, NULL,
				  DNS_RBTFIND_NOOPTIONS, NULL, NULL);
	if (result == DNS_R_PARTIALMATCH) {
		if (dns_name_issubdomain(foundname, anchor))
			result = ISC_R_SUCCESS;
	}
	if (result == ISC_R_SUCCESS) {
		nta = (dns_nta_t *) node->data;
		answer = ISC_TF(nta->expiry > now);
	}

	/* Deal with expired NTA */
	if (result == ISC_R_SUCCESS && !answer) {
		char nb[DNS_NAME_FORMATSIZE];

		if (locktype == isc_rwlocktype_read) {
			RWUNLOCK(&ntatable->rwlock, locktype);
			locktype = isc_rwlocktype_write;
			goto relock;
		}

		dns_name_format(foundname, nb, sizeof(nb));
		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DNSSEC,
			      DNS_LOGMODULE_NTA, ISC_LOG_INFO,
			      "deleting expired NTA at %s", nb);

		if (nta->timer != NULL) {
			(void) isc_timer_reset(nta->timer,
					       isc_timertype_inactive,
					       NULL, NULL, ISC_TRUE);
			isc_timer_detach(&nta->timer);
		}

		result = deletenode(ntatable, foundname);
		if (result != ISC_R_SUCCESS) {
			isc_log_write(dns_lctx, DNS_LOGCATEGORY_DNSSEC,
				      DNS_LOGMODULE_NTA, ISC_LOG_INFO,
				      "deleting NTA failed: %s",
				      isc_result_totext(result));
		}
		goto again;
	}
	RWUNLOCK(&ntatable->rwlock, locktype);

	return (answer);
}

static isc_result_t
putstr(isc_buffer_t **b, const char *str) {
	isc_result_t result;

	result = isc_buffer_reserve(b, strlen(str));
	if (result != ISC_R_SUCCESS)
		return (result);

	isc_buffer_putstr(*b, str);
	return (ISC_R_SUCCESS);
}

isc_result_t
dns_ntatable_totext(dns_ntatable_t *ntatable, isc_buffer_t **buf) {
	isc_result_t result;
	dns_rbtnode_t *node;
	dns_rbtnodechain_t chain;
	isc_boolean_t first = ISC_TRUE;
	isc_stdtime_t now;

	REQUIRE(VALID_NTATABLE(ntatable));

	isc_stdtime_get(&now);

	RWLOCK(&ntatable->rwlock, isc_rwlocktype_read);
	dns_rbtnodechain_init(&chain, ntatable->view->mctx);
	result = dns_rbtnodechain_first(&chain, ntatable->table, NULL, NULL);
	if (result != ISC_R_SUCCESS && result != DNS_R_NEWORIGIN) {
		if (result == ISC_R_NOTFOUND)
			result = ISC_R_SUCCESS;
		goto cleanup;
	}
	for (;;) {
		dns_rbtnodechain_current(&chain, NULL, NULL, &node);
		if (node->data != NULL) {
			dns_nta_t *n = (dns_nta_t *) node->data;
			char nbuf[DNS_NAME_FORMATSIZE];
			char tbuf[ISC_FORMATHTTPTIMESTAMP_SIZE];
			char obuf[DNS_NAME_FORMATSIZE +
				  ISC_FORMATHTTPTIMESTAMP_SIZE +
				  sizeof("expired:  \n")];
			dns_fixedname_t fn;
			dns_name_t *name;
			isc_time_t t;

			dns_fixedname_init(&fn);
			name = dns_fixedname_name(&fn);
			dns_rbt_fullnamefromnode(node, name);
			dns_name_format(name, nbuf, sizeof(nbuf));
			isc_time_set(&t, n->expiry, 0);
			isc_time_formattimestamp(&t, tbuf, sizeof(tbuf));

			snprintf(obuf, sizeof(obuf), "%s%s: %s %s",
				 first ? "" : "\n", nbuf,
				 n->expiry <= now ? "expired" : "expiry",
				 tbuf);
			first = ISC_FALSE;
			result = putstr(buf, obuf);
			if (result != ISC_R_SUCCESS)
				goto cleanup;
		}
		result = dns_rbtnodechain_next(&chain, NULL, NULL);
		if (result != ISC_R_SUCCESS && result != DNS_R_NEWORIGIN) {
			if (result == ISC_R_NOMORE)
				result = ISC_R_SUCCESS;
			break;
		}
	}

   cleanup:
	dns_rbtnodechain_invalidate(&chain);
	RWUNLOCK(&ntatable->rwlock, isc_rwlocktype_read);
	return (result);
}

#if 0
isc_result_t
dns_ntatable_dump(dns_ntatable_t *ntatable, FILE *fp) {
	isc_result_t result;
	dns_rbtnode_t *node;
	dns_rbtnodechain_t chain;
	isc_stdtime_t now;

	REQUIRE(VALID_NTATABLE(ntatable));

	isc_stdtime_get(&now);

	RWLOCK(&ntatable->rwlock, isc_rwlocktype_read);
	dns_rbtnodechain_init(&chain, ntatable->view->mctx);
	result = dns_rbtnodechain_first(&chain, ntatable->table, NULL, NULL);
	if (result != ISC_R_SUCCESS && result != DNS_R_NEWORIGIN)
		goto cleanup;
	for (;;) {
		dns_rbtnodechain_current(&chain, NULL, NULL, &node);
		if (node->data != NULL) {
			dns_nta_t *n = (dns_nta_t *) node->data;
			char nbuf[DNS_NAME_FORMATSIZE], tbuf[80];
			dns_fixedname_t fn;
			dns_name_t *name;
			isc_time_t t;

			dns_fixedname_init(&fn);
			name = dns_fixedname_name(&fn);
			dns_rbt_fullnamefromnode(node, name);
			dns_name_format(name, nbuf, sizeof(nbuf));
			isc_time_set(&t, n->expiry, 0);
			isc_time_formattimestamp(&t, tbuf, sizeof(tbuf));
			fprintf(fp, "%s: %s %s\n", nbuf,
				n->expiry <= now ? "expired" : "expiry",
				tbuf);
		}
		result = dns_rbtnodechain_next(&chain, NULL, NULL);
		if (result != ISC_R_SUCCESS && result != DNS_R_NEWORIGIN) {
			if (result == ISC_R_NOMORE)
				result = ISC_R_SUCCESS;
			break;
		}
	}

   cleanup:
	dns_rbtnodechain_invalidate(&chain);
	RWUNLOCK(&ntatable->rwlock, isc_rwlocktype_read);
	return (result);
}
#endif

isc_result_t
dns_ntatable_dump(dns_ntatable_t *ntatable, FILE *fp) {
	isc_result_t result;
	isc_buffer_t *text = NULL;
	int len = 4096;

	result = isc_buffer_allocate(ntatable->view->mctx, &text, len);
	if (result != ISC_R_SUCCESS)
		return (result);

	result = dns_ntatable_totext(ntatable, &text);

	if (isc_buffer_usedlength(text) != 0) {
		(void) putstr(&text, "\n");
	} else if (result == ISC_R_SUCCESS) {
		(void) putstr(&text, "none");
	} else {
		(void) putstr(&text, "could not dump NTA table: ");
		(void) putstr(&text, isc_result_totext(result));
	}

	fprintf(fp, "%.*s", (int) isc_buffer_usedlength(text),
		(char *) isc_buffer_base(text));
	isc_buffer_free(&text);
	return (result);
}

isc_result_t
dns_ntatable_save(dns_ntatable_t *ntatable, FILE *fp) {
	isc_result_t result;
	dns_rbtnode_t *node;
	dns_rbtnodechain_t chain;
	isc_stdtime_t now;
	isc_boolean_t written = ISC_FALSE;

	REQUIRE(VALID_NTATABLE(ntatable));

	isc_stdtime_get(&now);

	RWLOCK(&ntatable->rwlock, isc_rwlocktype_read);
	dns_rbtnodechain_init(&chain, ntatable->view->mctx);
	result = dns_rbtnodechain_first(&chain, ntatable->table, NULL, NULL);
	if (result != ISC_R_SUCCESS && result != DNS_R_NEWORIGIN)
		goto cleanup;

	for (;;) {
		dns_rbtnodechain_current(&chain, NULL, NULL, &node);
		if (node->data != NULL) {
			dns_nta_t *n = (dns_nta_t *) node->data;
			if (n->expiry > now) {
				isc_buffer_t b;
				char nbuf[DNS_NAME_FORMATSIZE + 1], tbuf[80];
				dns_fixedname_t fn;
				dns_name_t *name;

				dns_fixedname_init(&fn);
				name = dns_fixedname_name(&fn);
				dns_rbt_fullnamefromnode(node, name);

				isc_buffer_init(&b, nbuf, sizeof(nbuf));
				result = dns_name_totext(name, ISC_FALSE, &b);
				if (result != ISC_R_SUCCESS)
					goto skip;

				/* Zero terminate. */
				isc_buffer_putuint8(&b, 0);

				isc_buffer_init(&b, tbuf, sizeof(tbuf));
				dns_time32_totext(n->expiry, &b);

				/* Zero terminate. */
				isc_buffer_putuint8(&b, 0);

				fprintf(fp, "%s %s %s\n", nbuf,
					n->forced ? "forced" : "regular",
					tbuf);
				written = ISC_TRUE;
			}
		}
	skip:
		result = dns_rbtnodechain_next(&chain, NULL, NULL);
		if (result != ISC_R_SUCCESS && result != DNS_R_NEWORIGIN) {
			if (result == ISC_R_NOMORE)
				result = ISC_R_SUCCESS;
			break;
		}
	}

   cleanup:
	dns_rbtnodechain_invalidate(&chain);
	RWUNLOCK(&ntatable->rwlock, isc_rwlocktype_read);

	if (result != ISC_R_SUCCESS)
		return (result);
	else
		return (written ? ISC_R_SUCCESS : ISC_R_NOTFOUND);
}
