client.c

bind-3.2.

/*
 * Copyright (C) 1999-2003  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 INTERNET SOFTWARE CONSORTIUM
 * DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
 * INTERNET SOFTWARE CONSORTIUM 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: client.c,v 1.176.2.13 2003/07/18 06:14:30 marka Exp $ */

#include <config.h>

#include <isc/formatcheck.h>
#include <isc/mutex.h>
#include <isc/once.h>
#include <isc/print.h>
#include <isc/stdio.h>
#include <isc/string.h>
#include <isc/task.h>
#include <isc/timer.h>
#include <isc/util.h>

#include <dns/db.h>
#include <dns/dispatch.h>
#include <dns/events.h>
#include <dns/message.h>
#include <dns/rdata.h>
#include <dns/rdataclass.h>
#include <dns/rdatalist.h>
#include <dns/rdataset.h>
#include <dns/tsig.h>
#include <dns/view.h>
#include <dns/zone.h>

#include <named/interfacemgr.h>
#include <named/log.h>
#include <named/notify.h>
#include <named/server.h>
#include <named/update.h>

/***
 *** Client
 ***/

/*
 * Important note!
 *
 * All client state changes, other than that from idle to listening, occur
 * as a result of events.  This guarantees serialization and avoids the
 * need for locking.
 *
 * If a routine is ever created that allows someone other than the client's
 * task to change the client, then the client will have to be locked.
 */

#define NS_CLIENT_TRACE
#ifdef NS_CLIENT_TRACE
#define CTRACE(m)	ns_client_log(client, \
				      NS_LOGCATEGORY_CLIENT, \
				      NS_LOGMODULE_CLIENT, \
				      ISC_LOG_DEBUG(3), \
				      "%s", (m))
#define MTRACE(m)	isc_log_write(ns_g_lctx, \
				      NS_LOGCATEGORY_GENERAL, \
				      NS_LOGMODULE_CLIENT, \
				      ISC_LOG_DEBUG(3), \
				      "clientmgr @%p: %s", manager, (m))
#else
#define CTRACE(m)	((void)(m))
#define MTRACE(m)	((void)(m))
#endif

#define TCP_CLIENT(c)	(((c)->attributes & NS_CLIENTATTR_TCP) != 0)

#define TCP_BUFFER_SIZE			(65535 + 2)
#define SEND_BUFFER_SIZE		4096
#define RECV_BUFFER_SIZE		4096

struct ns_clientmgr {
	/* Unlocked. */
	unsigned int			magic;
	isc_mem_t *			mctx;
	isc_taskmgr_t *			taskmgr;
	isc_timermgr_t *		timermgr;
	isc_mutex_t			lock;
	/* Locked by lock. */
	isc_boolean_t			exiting;
	client_list_t			active; 	/* Active clients */
	client_list_t 			inactive;	/* To be recycled */
};

#define MANAGER_MAGIC			ISC_MAGIC('N', 'S', 'C', 'm')
#define VALID_MANAGER(m)		ISC_MAGIC_VALID(m, MANAGER_MAGIC)

/*
 * Client object states.  Ordering is significant: higher-numbered
 * states are generally "more active", meaning that the client can
 * have more dynamically allocated data, outstanding events, etc.
 * In the list below, any such properties listed for state N
 * also apply to any state > N.
 *
 * To force the client into a less active state, set client->newstate
 * to that state and call exit_check().  This will cause any
 * activities defined for higher-numbered states to be aborted.
 */

#define NS_CLIENTSTATE_FREED    0
/*
 * The client object no longer exists.
 */

#define NS_CLIENTSTATE_INACTIVE 1
/*
 * The client object exists and has a task and timer.
 * Its "query" struct and sendbuf are initialized.
 * It is on the client manager's list of inactive clients.
 * It has a message and OPT, both in the reset state.
 */

#define NS_CLIENTSTATE_READY    2
/*
 * The client object is either a TCP or a UDP one, and
 * it is associated with a network interface.  It is on the
 * client manager's list of active clients.
 *
 * If it is a TCP client object, it has a TCP listener socket
 * and an outstanding TCP listen request.
 *
 * If it is a UDP client object, it has a UDP listener socket
 * and an outstanding UDP receive request.
 */

#define NS_CLIENTSTATE_READING  3
/*
 * The client object is a TCP client object that has received
 * a connection.  It has a tcpsocket, tcpmsg, TCP quota, and an
 * outstanding TCP read request.  This state is not used for
 * UDP client objects.
 */

#define NS_CLIENTSTATE_WORKING  4
/*
 * The client object has received a request and is working
 * on it.  It has a view, and it may  have any of a non-reset OPT,
 * recursion quota, and an outstanding write request.
 */

#define NS_CLIENTSTATE_MAX      9
/*
 * Sentinel value used to indicate "no state".  When client->newstate
 * has this value, we are not attempting to exit the current state.
 * Must be greater than any valid state.
 */


static void client_read(ns_client_t *client);
static void client_accept(ns_client_t *client);
static void client_udprecv(ns_client_t *client);
static void clientmgr_destroy(ns_clientmgr_t *manager);
static isc_boolean_t exit_check(ns_client_t *client);
static void ns_client_endrequest(ns_client_t *client);
static void ns_client_checkactive(ns_client_t *client);
static void client_start(isc_task_t *task, isc_event_t *event);
static void client_request(isc_task_t *task, isc_event_t *event);
static void ns_client_dumpmessage(ns_client_t *client, const char *reason);

void
ns_client_settimeout(ns_client_t *client, unsigned int seconds) {
	isc_result_t result;
	isc_interval_t interval;

	isc_interval_set(&interval, seconds, 0);
	result = isc_timer_reset(client->timer, isc_timertype_once, NULL,
				 &interval, ISC_FALSE);
	client->timerset = ISC_TRUE;
	if (result != ISC_R_SUCCESS) {
		ns_client_log(client, NS_LOGCATEGORY_CLIENT,
			      NS_LOGMODULE_CLIENT, ISC_LOG_ERROR,
			      "setting timeout: %s",
			      isc_result_totext(result));
		/* Continue anyway. */
	}
}

/*
 * Check for a deactivation or shutdown request and take appropriate
 * action.  Returns ISC_TRUE if either is in progress; in this case
 * the caller must no longer use the client object as it may have been
 * freed.
 */
static isc_boolean_t
exit_check(ns_client_t *client) {
	ns_clientmgr_t *locked_manager = NULL;
	ns_clientmgr_t *destroy_manager = NULL;

	REQUIRE(NS_CLIENT_VALID(client));

	if (client->state <= client->newstate)
		return (ISC_FALSE); /* Business as usual. */

	INSIST(client->newstate < NS_CLIENTSTATE_WORKING);

	/*
	 * We need to detach from the view early when shutting down
	 * the server to break the following vicious circle:
	 *
	 *  - The resolver will not shut down until the view refcount is zero
	 *  - The view refcount does not go to zero until all clients detach
	 *  - The client does not detach from the view until references is zero
	 *  - references does not go to zero until the resolver has shut down
	 *
	 */
	if (client->newstate == NS_CLIENTSTATE_FREED && client->view != NULL)
		dns_view_detach(&client->view);

	if (client->state == NS_CLIENTSTATE_WORKING) {
		INSIST(client->newstate <= NS_CLIENTSTATE_READING);
		/*
		 * We are trying to abort request processing.
		 */
		if (client->nsends > 0) {
			isc_socket_t *socket;
			if (TCP_CLIENT(client))
				socket = client->tcpsocket;
			else
				socket = client->udpsocket;
			isc_socket_cancel(socket, client->task,
					  ISC_SOCKCANCEL_SEND);
		}

		if (! (client->nsends == 0 && client->nrecvs == 0 &&
		       client->references == 0))
		{
			/*
			 * Still waiting for I/O cancel completion.
			 * or lingering references.
			 */
			return (ISC_TRUE);
		}
		/*
		 * I/O cancel is complete.  Burn down all state
		 * related to the current request.
		 */
		ns_client_endrequest(client);

		client->state = NS_CLIENTSTATE_READING;
		INSIST(client->recursionquota == NULL);
		if (NS_CLIENTSTATE_READING == client->newstate) {
			client_read(client);
			client->newstate = NS_CLIENTSTATE_MAX;
			return (ISC_TRUE); /* We're done. */
		}
	}

	if (client->state == NS_CLIENTSTATE_READING) {
		/*
		 * We are trying to abort the current TCP connection,
		 * if any.
		 */
		INSIST(client->recursionquota == NULL);
		INSIST(client->newstate <= NS_CLIENTSTATE_READY);
		if (client->nreads > 0)
			dns_tcpmsg_cancelread(&client->tcpmsg);
		if (! client->nreads == 0) {
			/* Still waiting for read cancel completion. */
			return (ISC_TRUE);
		}

		if (client->tcpmsg_valid) {
			dns_tcpmsg_invalidate(&client->tcpmsg);
			client->tcpmsg_valid = ISC_FALSE;
		}
		if (client->tcpsocket != NULL) {
			CTRACE("closetcp");
			isc_socket_detach(&client->tcpsocket);
		}

		if (client->tcpquota != NULL)
			isc_quota_detach(&client->tcpquota);

		if (client->timerset) {
			(void) isc_timer_reset(client->timer,
					       isc_timertype_inactive,
					       NULL, NULL, ISC_TRUE);
			client->timerset = ISC_FALSE;
		}

		client->peeraddr_valid = ISC_FALSE;

		client->state = NS_CLIENTSTATE_READY;
		INSIST(client->recursionquota == NULL);

		/*
		 * Now the client is ready to accept a new TCP connection
		 * or UDP request, but we may have enough clients doing
		 * that already.  Check whether this client needs to remain
		 * active and force it to go inactive if not.
		 */
		ns_client_checkactive(client);

		if (NS_CLIENTSTATE_READY == client->newstate) {
			if (TCP_CLIENT(client)) {
				client_accept(client);
			} else
				client_udprecv(client);
			client->newstate = NS_CLIENTSTATE_MAX;
			return (ISC_TRUE);
		}
	}

	if (client->state == NS_CLIENTSTATE_READY) {
		INSIST(client->newstate <= NS_CLIENTSTATE_INACTIVE);
		/*
		 * We are trying to enter the inactive state.
		 */
		if (client->naccepts > 0)
			isc_socket_cancel(client->tcplistener, client->task,
					  ISC_SOCKCANCEL_ACCEPT);

		if (! (client->naccepts == 0)) {
			/* Still waiting for accept cancel completion. */
			return (ISC_TRUE);
		}
		/* Accept cancel is complete. */

		if (client->nrecvs > 0)
			isc_socket_cancel(client->udpsocket, client->task,
					  ISC_SOCKCANCEL_RECV);
		if (! (client->nrecvs == 0)) {
			/* Still waiting for recv cancel completion. */
			return (ISC_TRUE);
		}
		/* Recv cancel is complete. */

		if (client->nctls > 0) {
			/* Still waiting for control event to be delivered */
			return (ISC_TRUE);
		}

		/* Deactivate the client. */
		if (client->interface)
			ns_interface_detach(&client->interface);

		INSIST(client->naccepts == 0);
		INSIST(client->recursionquota == NULL);
		if (client->tcplistener != NULL)
			isc_socket_detach(&client->tcplistener);

		if (client->udpsocket != NULL)
			isc_socket_detach(&client->udpsocket);

		if (client->dispatch != NULL)
			dns_dispatch_detach(&client->dispatch);

		client->attributes = 0;
		client->mortal = ISC_FALSE;

		LOCK(&client->manager->lock);
		/*
		 * Put the client on the inactive list.  If we are aiming for
		 * the "freed" state, it will be removed from the inactive
		 * list shortly, and we need to keep the manager locked until
		 * that has been done, lest the manager decide to reactivate
		 * the dying client inbetween.
		 */
		locked_manager = client->manager;
		ISC_LIST_UNLINK(*client->list, client, link);
		ISC_LIST_APPEND(client->manager->inactive, client, link);
		client->list = &client->manager->inactive;
		client->state = NS_CLIENTSTATE_INACTIVE;
		INSIST(client->recursionquota == NULL);

		if (client->state == client->newstate) {
			client->newstate = NS_CLIENTSTATE_MAX;
			goto unlock;
		}
	}

	if (client->state == NS_CLIENTSTATE_INACTIVE) {
		INSIST(client->newstate == NS_CLIENTSTATE_FREED);
		/*
		 * We are trying to free the client.
		 *
		 * When "shuttingdown" is true, either the task has received
		 * its shutdown event or no shutdown event has ever been
		 * set up.  Thus, we have no outstanding shutdown
		 * event at this point.
		 */
		REQUIRE(client->state == NS_CLIENTSTATE_INACTIVE);

		INSIST(client->recursionquota == NULL);

		ns_query_free(client);
		isc_mem_put(client->mctx, client->recvbuf, RECV_BUFFER_SIZE);
		isc_event_free((isc_event_t **)&client->sendevent);
		isc_event_free((isc_event_t **)&client->recvevent);
		isc_timer_detach(&client->timer);

		if (client->tcpbuf != NULL)
			isc_mem_put(client->mctx, client->tcpbuf, TCP_BUFFER_SIZE);
		if (client->opt != NULL) {
			INSIST(dns_rdataset_isassociated(client->opt));
			dns_rdataset_disassociate(client->opt);
			dns_message_puttemprdataset(client->message, &client->opt);
		}
		dns_message_destroy(&client->message);
		if (client->manager != NULL) {
			ns_clientmgr_t *manager = client->manager;
			if (locked_manager == NULL) {
				LOCK(&manager->lock);
				locked_manager = manager;
			}
			ISC_LIST_UNLINK(*client->list, client, link);
			client->list = NULL;
			if (manager->exiting &&
			    ISC_LIST_EMPTY(manager->active) &&
			    ISC_LIST_EMPTY(manager->inactive))
				destroy_manager = manager;
		}
		/*
		 * Detaching the task must be done after unlinking from
		 * the manager's lists because the manager accesses
		 * client->task.
		 */
		if (client->task != NULL)
			isc_task_detach(&client->task);

		CTRACE("free");
		client->magic = 0;
		isc_mem_put(client->mctx, client, sizeof(*client));

		goto unlock;
	}

 unlock:
	if (locked_manager != NULL) {
		UNLOCK(&locked_manager->lock);
		locked_manager = NULL;
	}

	/*
	 * Only now is it safe to destroy the client manager (if needed),
	 * because we have accessed its lock for the last time.
	 */
	if (destroy_manager != NULL)
		clientmgr_destroy(destroy_manager);

	return (ISC_TRUE);
}

/*
 * The client's task has received the client's control event
 * as part of the startup process.
 */
static void
client_start(isc_task_t *task, isc_event_t *event) {
	ns_client_t *client = (ns_client_t *) event->ev_arg;

	INSIST(task == client->task);

	UNUSED(task);

	INSIST(client->nctls == 1);
	client->nctls--;

	if (exit_check(client))
		return;

	if (TCP_CLIENT(client)) {
		client_accept(client);
	} else {
		client_udprecv(client);
	}
}


/*
 * The client's task has received a shutdown event.
 */
static void
client_shutdown(isc_task_t *task, isc_event_t *event) {
	ns_client_t *client;

	REQUIRE(event != NULL);
	REQUIRE(event->ev_type == ISC_TASKEVENT_SHUTDOWN);
	client = event->ev_arg;
	REQUIRE(NS_CLIENT_VALID(client));
	REQUIRE(task == client->task);

	UNUSED(task);

	CTRACE("shutdown");

	isc_event_free(&event);

	if (client->shutdown != NULL) {
		(client->shutdown)(client->shutdown_arg, ISC_R_SHUTTINGDOWN);
		client->shutdown = NULL;
		client->shutdown_arg = NULL;
	}

	client->newstate = NS_CLIENTSTATE_FREED;
	(void)exit_check(client);
}


static void
ns_client_endrequest(ns_client_t *client) {
	INSIST(client->naccepts == 0);
	INSIST(client->nreads == 0);
	INSIST(client->nsends == 0);
	INSIST(client->nrecvs == 0);
	INSIST(client->state == NS_CLIENTSTATE_WORKING);

	CTRACE("endrequest");

	if (client->next != NULL) {
		(client->next)(client);
		client->next = NULL;
	}

	if (client->view != NULL)
		dns_view_detach(&client->view);
	if (client->opt != NULL) {
		INSIST(dns_rdataset_isassociated(client->opt));
		dns_rdataset_disassociate(client->opt);
		dns_message_puttemprdataset(client->message, &client->opt);
	}

	client->udpsize = 512;
	client->extflags = 0;
	dns_message_reset(client->message, DNS_MESSAGE_INTENTPARSE);

	if (client->recursionquota != NULL)
		isc_quota_detach(&client->recursionquota);

	/*
	 * Clear all client attributes that are specific to