resolver.c

bind-3.2.

	if (bucket_empty)
		empty_bucket(res);
}

static void
fctx_start(isc_task_t *task, isc_event_t *event) {
	fetchctx_t *fctx = event->ev_arg;
	isc_boolean_t done = ISC_FALSE, bucket_empty = ISC_FALSE;
	dns_resolver_t *res;
	unsigned int bucketnum;

	REQUIRE(VALID_FCTX(fctx));

	UNUSED(task);

	res = fctx->res;
	bucketnum = fctx->bucketnum;

	FCTXTRACE("start");

	LOCK(&res->buckets[bucketnum].lock);

	INSIST(fctx->state == fetchstate_init);
	if (fctx->want_shutdown) {
		/*
		 * We haven't started this fctx yet, and we've been requested
		 * to shut it down.
		 */
		fctx->attributes |= FCTX_ATTR_SHUTTINGDOWN;
		fctx->state = fetchstate_done;
		fctx_sendevents(fctx, ISC_R_CANCELED);
		/*
		 * Since we haven't started, we INSIST that we have no
		 * pending ADB finds and no pending validations.
		 */
		INSIST(fctx->pending == 0);
		INSIST(ISC_LIST_EMPTY(fctx->validators));
		if (fctx->references == 0) {
			/*
			 * It's now safe to destroy this fctx.
			 */
			bucket_empty = fctx_destroy(fctx);
		}
		done = ISC_TRUE;
	} else {
		/*
		 * Normal fctx startup.
		 */
		fctx->state = fetchstate_active;
		/*
		 * Reset the control event for later use in shutting down
		 * the fctx.
		 */
		ISC_EVENT_INIT(event, sizeof(*event), 0, NULL,
			       DNS_EVENT_FETCHCONTROL, fctx_doshutdown, fctx,
			       NULL, NULL, NULL);
	}

	UNLOCK(&res->buckets[bucketnum].lock);

	if (!done) {
		/*
		 * All is well.  Start working on the fetch.
		 */
		fctx_starttimer(fctx);
		fctx_try(fctx);
	} else if (bucket_empty)
		empty_bucket(res);
}

/*
 * Fetch Creation, Joining, and Cancelation.
 */

static inline isc_result_t
fctx_join(fetchctx_t *fctx, isc_task_t *task, isc_taskaction_t action,
	  void *arg, dns_rdataset_t *rdataset, dns_rdataset_t *sigrdataset,
	  dns_fetch_t *fetch)
{
	isc_task_t *clone;
	dns_fetchevent_t *event;

	FCTXTRACE("join");

	/*
	 * We store the task we're going to send this event to in the
	 * sender field.  We'll make the fetch the sender when we actually
	 * send the event.
	 */
	clone = NULL;
	isc_task_attach(task, &clone);
	event = (dns_fetchevent_t *)
		isc_event_allocate(fctx->res->mctx, clone,
				   DNS_EVENT_FETCHDONE,
				   action, arg, sizeof *event);
	if (event == NULL) {
		isc_task_detach(&clone);
		return (ISC_R_NOMEMORY);
	}
	event->result = DNS_R_SERVFAIL;
	event->qtype = fctx->type;
	event->db = NULL;
	event->node = NULL;
	event->rdataset = rdataset;
	event->sigrdataset = sigrdataset;
	event->fetch = fetch;
	dns_fixedname_init(&event->foundname);

	/*
	 * Make sure that we can store the sigrdataset in the
	 * first event if it is needed by any of the events.
	 */
	if (event->sigrdataset != NULL)
		ISC_LIST_PREPEND(fctx->events, event, ev_link);
	else
		ISC_LIST_APPEND(fctx->events, event, ev_link);
	fctx->references++;

	fetch->magic = DNS_FETCH_MAGIC;
	fetch->private = fctx;

	return (ISC_R_SUCCESS);
}

static isc_result_t
fctx_create(dns_resolver_t *res, dns_name_t *name, dns_rdatatype_t type,
	    dns_name_t *domain, dns_rdataset_t *nameservers,
	    unsigned int options, unsigned int bucketnum, fetchctx_t **fctxp)
{
	fetchctx_t *fctx;
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t iresult;
	isc_interval_t interval;
	dns_fixedname_t qdomain;
	unsigned int findoptions = 0;

	/*
	 * Caller must be holding the lock for bucket number 'bucketnum'.
	 */
	REQUIRE(fctxp != NULL && *fctxp == NULL);

	fctx = isc_mem_get(res->mctx, sizeof *fctx);
	if (fctx == NULL)
		return (ISC_R_NOMEMORY);
	FCTXTRACE("create");
	dns_name_init(&fctx->name, NULL);
	result = dns_name_dup(name, res->mctx, &fctx->name);
	if (result != ISC_R_SUCCESS)
		goto cleanup_fetch;
	dns_name_init(&fctx->domain, NULL);
	dns_rdataset_init(&fctx->nameservers);

	fctx->type = type;
	fctx->options = options;
	/*
	 * Note!  We do not attach to the task.  We are relying on the
	 * resolver to ensure that this task doesn't go away while we are
	 * using it.
	 */
	fctx->res = res;
	fctx->references = 0;
	fctx->bucketnum = bucketnum;
	fctx->state = fetchstate_init;
	fctx->want_shutdown = ISC_FALSE;
	fctx->cloned = ISC_FALSE;
	ISC_LIST_INIT(fctx->queries);
	ISC_LIST_INIT(fctx->finds);
	ISC_LIST_INIT(fctx->forwaddrs);
	ISC_LIST_INIT(fctx->forwarders);
	fctx->fwdpolicy = dns_fwdpolicy_none;
	ISC_LIST_INIT(fctx->bad);
	ISC_LIST_INIT(fctx->validators);
	fctx->find = NULL;
	fctx->pending = 0;
	fctx->restarts = 0;
	fctx->timeouts = 0;
	if (dns_name_requiresedns(name))
		fctx->attributes = FCTX_ATTR_NEEDEDNS0;
	else
		fctx->attributes = 0;

	if (domain == NULL) {
		dns_forwarders_t *forwarders = NULL;
		result = dns_fwdtable_find(fctx->res->view->fwdtable,
					   &fctx->name, &forwarders);
		if (result == ISC_R_SUCCESS)
			fctx->fwdpolicy = forwarders->fwdpolicy;

		if (fctx->fwdpolicy != dns_fwdpolicy_only) {
			/*
			 * The caller didn't supply a query domain and
			 * nameservers, and we're not in forward-only mode,
			 * so find the best nameservers to use.
			 */
			if (type == dns_rdatatype_key)
				findoptions |= DNS_DBFIND_NOEXACT;
			dns_fixedname_init(&qdomain);
			result = dns_view_findzonecut(res->view, name,
					      dns_fixedname_name(&qdomain), 0,
						      findoptions, ISC_TRUE,
						      &fctx->nameservers,
						      NULL);
			if (result != ISC_R_SUCCESS)
				goto cleanup_name;
			result = dns_name_dup(dns_fixedname_name(&qdomain),
					      res->mctx, &fctx->domain);
			if (result != ISC_R_SUCCESS) {
				dns_rdataset_disassociate(&fctx->nameservers);
				goto cleanup_name;
			}
		} else {
			/*
			 * We're in forward-only mode.  Set the query domain
			 * to ".".
			 */
			result = dns_name_dup(dns_rootname, res->mctx,
					      &fctx->domain);
			if (result != ISC_R_SUCCESS)
				goto cleanup_name;
		}
	} else {
		result = dns_name_dup(domain, res->mctx, &fctx->domain);
		if (result != ISC_R_SUCCESS)
			goto cleanup_name;
		dns_rdataset_clone(nameservers, &fctx->nameservers);
	}

	INSIST(dns_name_issubdomain(&fctx->name, &fctx->domain));

	fctx->qmessage = NULL;
	result = dns_message_create(res->mctx, DNS_MESSAGE_INTENTRENDER,
				    &fctx->qmessage);

	if (result != ISC_R_SUCCESS)
		goto cleanup_domain;

	fctx->rmessage = NULL;
	result = dns_message_create(res->mctx, DNS_MESSAGE_INTENTPARSE,
				    &fctx->rmessage);

	if (result != ISC_R_SUCCESS)
		goto cleanup_qmessage;

	/*
	 * Compute an expiration time for the entire fetch.
	 */
	isc_interval_set(&interval, 30, 0);		/* XXXRTH constant */
	iresult = isc_time_nowplusinterval(&fctx->expires, &interval);
	if (iresult != ISC_R_SUCCESS) {
		UNEXPECTED_ERROR(__FILE__, __LINE__,
				 "isc_time_nowplusinterval: %s",
				 isc_result_totext(iresult));
		result = ISC_R_UNEXPECTED;
		goto cleanup_rmessage;
	}

	/*
	 * Default retry interval initialization.  We set the interval now
	 * mostly so it won't be uninitialized.  It will be set to the
	 * correct value before a query is issued.
	 */
	isc_interval_set(&fctx->interval, 2, 0);

	/*
	 * Create an inactive timer.  It will be made active when the fetch
	 * is actually started.
	 */
	fctx->timer = NULL;
	iresult = isc_timer_create(res->timermgr, isc_timertype_inactive,
				   NULL, NULL,
				   res->buckets[bucketnum].task, fctx_timeout,
				   fctx, &fctx->timer);
	if (iresult != ISC_R_SUCCESS) {
		UNEXPECTED_ERROR(__FILE__, __LINE__,
				 "isc_timer_create: %s",
				 isc_result_totext(iresult));
		result = ISC_R_UNEXPECTED;
		goto cleanup_rmessage;
	}

	/*
	 * Attach to the view's cache and adb.
	 */
	fctx->cache = NULL;
	dns_db_attach(res->view->cachedb, &fctx->cache);
	fctx->adb = NULL;
	dns_adb_attach(res->view->adb, &fctx->adb);

	ISC_LIST_INIT(fctx->events);
	ISC_LINK_INIT(fctx, link);
	fctx->magic = FCTX_MAGIC;

	ISC_LIST_APPEND(res->buckets[bucketnum].fctxs, fctx, link);

	*fctxp = fctx;

	return (ISC_R_SUCCESS);

 cleanup_rmessage:
	dns_message_destroy(&fctx->rmessage);

 cleanup_qmessage:
	dns_message_destroy(&fctx->qmessage);

 cleanup_domain:
	if (dns_name_countlabels(&fctx->domain) > 0)
		dns_name_free(&fctx->domain, res->mctx);
	if (dns_rdataset_isassociated(&fctx->nameservers))
		dns_rdataset_disassociate(&fctx->nameservers);

 cleanup_name:
	dns_name_free(&fctx->name, res->mctx);

 cleanup_fetch:
	isc_mem_put(res->mctx, fctx, sizeof *fctx);

	return (result);
}

/*
 * Handle Responses
 */
static inline isc_boolean_t
is_lame(fetchctx_t *fctx) {
	dns_message_t *message = fctx->rmessage;
	dns_name_t *name;
	dns_rdataset_t *rdataset;
	isc_result_t result;

	if (message->rcode != dns_rcode_noerror &&
	    message->rcode != dns_rcode_nxdomain)
		return (ISC_FALSE);

	if (message->counts[DNS_SECTION_ANSWER] != 0)
		return (ISC_FALSE);

	if (message->counts[DNS_SECTION_AUTHORITY] == 0)
		return (ISC_FALSE);

	result = dns_message_firstname(message, DNS_SECTION_AUTHORITY);
	while (result == ISC_R_SUCCESS) {
		name = NULL;
		dns_message_currentname(message, DNS_SECTION_AUTHORITY, &name);
		for (rdataset = ISC_LIST_HEAD(name->list);
		     rdataset != NULL;
		     rdataset = ISC_LIST_NEXT(rdataset, link)) {
			dns_namereln_t namereln;
			int order;
			unsigned int labels, bits;
			if (rdataset->type != dns_rdatatype_ns)
				continue;
			namereln = dns_name_fullcompare(name, &fctx->domain,
				   			&order, &labels, &bits);
			if (namereln == dns_namereln_equal &&
			    (message->flags & DNS_MESSAGEFLAG_AA) != 0)
				return (ISC_FALSE);
			if (namereln == dns_namereln_subdomain)
				return (ISC_FALSE);
			return (ISC_TRUE);
		}
		result = dns_message_nextname(message, DNS_SECTION_AUTHORITY);
	}

	return (ISC_FALSE);
}

static inline void
log_lame(fetchctx_t *fctx, dns_adbaddrinfo_t *addrinfo) {
	char namebuf[DNS_NAME_FORMATSIZE];
	char domainbuf[DNS_NAME_FORMATSIZE];	
	char addrbuf[ISC_SOCKADDR_FORMATSIZE];
	
	dns_name_format(&fctx->name, namebuf, sizeof(namebuf));
	dns_name_format(&fctx->domain, domainbuf, sizeof(domainbuf));
	isc_sockaddr_format(&addrinfo->sockaddr, addrbuf, sizeof(addrbuf));
	isc_log_write(dns_lctx, DNS_LOGCATEGORY_LAME_SERVERS,
		      DNS_LOGMODULE_RESOLVER, ISC_LOG_INFO,
		      "lame server resolving '%s' (in '%s'?): %s",
		      namebuf, domainbuf, addrbuf);
}

static inline isc_result_t
same_question(fetchctx_t *fctx) {
	isc_result_t result;
	dns_message_t *message = fctx->rmessage;
	dns_name_t *name;
	dns_rdataset_t *rdataset;

	/*
	 * Caller must be holding the fctx lock.
	 */

	/*
	 * XXXRTH  Currently we support only one question.
	 */
	if (message->counts[DNS_SECTION_QUESTION] != 1)
		return (DNS_R_FORMERR);

	result = dns_message_firstname(message, DNS_SECTION_QUESTION);
	if (result != ISC_R_SUCCESS)
		return (result);
	name = NULL;
	dns_message_currentname(message, DNS_SECTION_QUESTION, &name);
	rdataset = ISC_LIST_HEAD(name->list);
	INSIST(rdataset != NULL);
	INSIST(ISC_LIST_NEXT(rdataset, link) == NULL);
	if (fctx->type != rdataset->type ||
	    fctx->res->rdclass != rdataset->rdclass ||
	    !dns_name_equal(&fctx->name, name))
		return (DNS_R_FORMERR);

	return (ISC_R_SUCCESS);
}

static void
clone_results(fetchctx_t *fctx) {
	dns_fetchevent_t *event, *hevent;
	isc_result_t result;
	dns_name_t *name, *hname;

	/*
	 * Set up any other events to have the same data as the first
	 * event.
	 *
	 * Caller must be holding the appropriate lock.
	 */

	fctx->cloned = ISC_TRUE;
	hevent = ISC_LIST_HEAD(fctx->events);
	if (hevent == NULL)
		return;
	hname = dns_fixedname_name(&hevent->foundname);
	for (event = ISC_LIST_NEXT(hevent, ev_link);
	     event != NULL;
	     event = ISC_LIST_NEXT(event, ev_link)) {
		name = dns_fixedname_name(&event->foundname);
		result = dns_name_copy(hname, name, NULL);
		if (result != ISC_R_SUCCESS)
			event->result = result;
		else
			event->result = hevent->result;
		dns_db_attach(hevent->db, &event->db);
		dns_db_attachnode(hevent->db, hevent->node, &event->node);
		INSIST(hevent->rdataset != NULL);
		INSIST(event->rdataset != NULL);
		if (dns_rdataset_isassociated(hevent->rdataset))
			dns_rdataset_clone(hevent->rdataset, event->rdataset);
		INSIST(! (hevent->sigrdataset == NULL &&
			  event->sigrdataset != NULL));
		if (hevent->sigrdataset != NULL &&
		    dns_rdataset_isassociated(hevent->sigrdataset) &&
		    event->sigrdataset != NULL)
			dns_rdataset_clone(hevent->sigrdataset,
					   event->sigrdataset);
	}
}

#define CACHE(r)	(((r)->attributes & DNS_RDATASETATTR_CACHE) != 0)
#define ANSWER(r)	(((r)->attributes & DNS_RDATASETATTR_ANSWER) != 0)
#define ANSWERSIG(r)	(((r)->attributes & DNS_RDATASETATTR_ANSWERSIG) != 0)
#define EXTERNAL(r)	(((r)->attributes & DNS_RDATASETATTR_EXTERNAL) != 0)
#define CHAINING(r)	(((r)->attributes & DNS_RDATASETATTR_CHAINING) != 0)
#define CHASE(r)	(((r)->attributes & DNS_RDATASETATTR_CHASE) != 0)


/*
 * Destroy '*fctx' if it is ready to be destroyed (i.e., if it has
 * no references and is no longer waiting for any events).  If this
 * was the last fctx in the resolver, destroy the resolver.
 *
 * Requires:
 *	'*fctx' is shutting down.
 */
static void
maybe_destroy(fetchctx_t *fctx) {
	unsigned int bucketnum;
	isc_boolean_t bucket_empty = ISC_FALSE;
	dns_resolver_t *res = fctx->res;

	REQUIRE(SHUTTINGDOWN(fctx));

	if (fctx->pending != 0 || !ISC_LIST_EMPTY(fctx->validators))
		return;

	bucketnum = fctx->bucketnum;
	LOCK(&res->buckets[bucketnum].lock);
	if (fctx->references == 0)
		bucket_empty = fctx_destroy(fctx);
	UNLOCK(&res->buckets[bucketnum].lock);

	if (bucket_empty)
		empty_bucket(res);
}

/*
 * The validator has finished.
 */
static void
validated(isc_task_t *task, isc_event_t *event) {
	isc_result_t result = ISC_R_SUCCESS;
	isc_result_t eresult = ISC_R_SUCCESS;
	isc_stdtime_t now;
	fetchctx_t *fctx;
	dns_validatorevent_t *vevent;
	dns_fetchevent_t *hevent;
	dns_rdataset_t *ardataset = NULL;
	dns_rdataset_t *asigrdataset = NULL;
	dns_dbnode_t *node = NULL;
	isc_boolean_t negative;
	isc_boolean_t chaining;
	isc_boolean_t sentresponse;
	isc_uint32_t tt