dispatch.c

bind 9.3结合mysql数据库

/*
 * Copyright (C) 2004  Internet Systems Consortium, Inc. ("ISC")
 * 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 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: dispatch.c,v 1.101.2.6.2.10 2004/09/01 04:27:41 marka Exp $ */

#include <config.h>

#include <stdlib.h>

#include <isc/entropy.h>
#include <isc/lfsr.h>
#include <isc/mem.h>
#include <isc/mutex.h>
#include <isc/print.h>
#include <isc/string.h>
#include <isc/task.h>
#include <isc/util.h>

#include <dns/acl.h>
#include <dns/dispatch.h>
#include <dns/events.h>
#include <dns/log.h>
#include <dns/message.h>
#include <dns/portlist.h>
#include <dns/tcpmsg.h>
#include <dns/types.h>

typedef ISC_LIST(dns_dispentry_t)	dns_displist_t;

typedef struct dns_qid {
	unsigned int	magic;
	unsigned int	qid_nbuckets;	/* hash table size */
	unsigned int	qid_increment;	/* id increment on collision */
	isc_mutex_t	lock;
	isc_lfsr_t	qid_lfsr1;	/* state generator info */
	isc_lfsr_t	qid_lfsr2;	/* state generator info */
	dns_displist_t	*qid_table;	/* the table itself */
} dns_qid_t;

struct dns_dispatchmgr {
	/* Unlocked. */
	unsigned int			magic;
	isc_mem_t		       *mctx;
	dns_acl_t		       *blackhole;
	dns_portlist_t		       *portlist;

	/* Locked by "lock". */
	isc_mutex_t			lock;
	unsigned int			state;
	ISC_LIST(dns_dispatch_t)	list;

	/* locked by buffer lock */
	dns_qid_t			*qid;
	isc_mutex_t			buffer_lock;
	unsigned int			buffers;    /* allocated buffers */
	unsigned int			buffersize; /* size of each buffer */
	unsigned int			maxbuffers; /* max buffers */

	/* Locked internally. */
	isc_mutex_t			pool_lock;
	isc_mempool_t		       *epool;	/* memory pool for events */
	isc_mempool_t		       *rpool;	/* memory pool for replies */
	isc_mempool_t		       *dpool;  /* dispatch allocations */
	isc_mempool_t		       *bpool;	/* memory pool for buffers */

	isc_entropy_t		       *entropy; /* entropy source */
};

#define MGR_SHUTTINGDOWN		0x00000001U
#define MGR_IS_SHUTTINGDOWN(l)	(((l)->state & MGR_SHUTTINGDOWN) != 0)

#define IS_PRIVATE(d)	(((d)->attributes & DNS_DISPATCHATTR_PRIVATE) != 0)

struct dns_dispentry {
	unsigned int			magic;
	dns_dispatch_t		       *disp;
	dns_messageid_t			id;
	unsigned int			bucket;
	isc_sockaddr_t			host;
	isc_task_t		       *task;
	isc_taskaction_t		action;
	void			       *arg;
	isc_boolean_t			item_out;
	ISC_LIST(dns_dispatchevent_t)	items;
	ISC_LINK(dns_dispentry_t)	link;
};

#define INVALID_BUCKET		(0xffffdead)

struct dns_dispatch {
	/* Unlocked. */
	unsigned int		magic;		/* magic */
	dns_dispatchmgr_t      *mgr;		/* dispatch manager */
	isc_task_t	       *task;		/* internal task */
	isc_socket_t	       *socket;		/* isc socket attached to */
	isc_sockaddr_t		local;		/* local address */
	unsigned int		maxrequests;	/* max requests */
	isc_event_t	       *ctlevent;

	/* Locked by mgr->lock. */
	ISC_LINK(dns_dispatch_t) link;

	/* Locked by "lock". */
	isc_mutex_t		lock;		/* locks all below */
	isc_sockettype_t	socktype;
	unsigned int		attributes;
	unsigned int		refcount;	/* number of users */
	dns_dispatchevent_t    *failsafe_ev;	/* failsafe cancel event */
	unsigned int		shutting_down : 1,
				shutdown_out : 1,
				connected : 1,
				tcpmsg_valid : 1,
				recv_pending : 1; /* is a recv() pending? */
	isc_result_t		shutdown_why;
	unsigned int		requests;	/* how many requests we have */
	unsigned int		tcpbuffers;	/* allocated buffers */
	dns_tcpmsg_t		tcpmsg;		/* for tcp streams */
	dns_qid_t		*qid;
};

#define QID_MAGIC		ISC_MAGIC('Q', 'i', 'd', ' ')
#define VALID_QID(e)		ISC_MAGIC_VALID((e), QID_MAGIC)

#define RESPONSE_MAGIC		ISC_MAGIC('D', 'r', 's', 'p')
#define VALID_RESPONSE(e)	ISC_MAGIC_VALID((e), RESPONSE_MAGIC)

#define DISPATCH_MAGIC		ISC_MAGIC('D', 'i', 's', 'p')
#define VALID_DISPATCH(e)	ISC_MAGIC_VALID((e), DISPATCH_MAGIC)

#define DNS_DISPATCHMGR_MAGIC	ISC_MAGIC('D', 'M', 'g', 'r')
#define VALID_DISPATCHMGR(e)	ISC_MAGIC_VALID((e), DNS_DISPATCHMGR_MAGIC)

#define DNS_QID(disp) ((disp)->socktype == isc_sockettype_tcp) ? \
		       (disp)->qid : (disp)->mgr->qid
/*
 * Statics.
 */
static dns_dispentry_t *bucket_search(dns_qid_t *, isc_sockaddr_t *,
				      dns_messageid_t, unsigned int);
static isc_boolean_t destroy_disp_ok(dns_dispatch_t *);
static void destroy_disp(isc_task_t *task, isc_event_t *event);
static void udp_recv(isc_task_t *, isc_event_t *);
static void tcp_recv(isc_task_t *, isc_event_t *);
static void startrecv(dns_dispatch_t *);
static dns_messageid_t dns_randomid(dns_qid_t *);
static isc_uint32_t dns_hash(dns_qid_t *, isc_sockaddr_t *, dns_messageid_t);
static void free_buffer(dns_dispatch_t *disp, void *buf, unsigned int len);
static void *allocate_udp_buffer(dns_dispatch_t *disp);
static inline void free_event(dns_dispatch_t *disp, dns_dispatchevent_t *ev);
static inline dns_dispatchevent_t *allocate_event(dns_dispatch_t *disp);
static void do_cancel(dns_dispatch_t *disp);
static dns_dispentry_t *linear_first(dns_qid_t *disp);
static dns_dispentry_t *linear_next(dns_qid_t *disp,
				    dns_dispentry_t *resp);
static void dispatch_free(dns_dispatch_t **dispp);
static isc_result_t dispatch_createudp(dns_dispatchmgr_t *mgr,
				       isc_socketmgr_t *sockmgr,
				       isc_taskmgr_t *taskmgr,
				       isc_sockaddr_t *localaddr,
				       unsigned int maxrequests,
				       unsigned int attributes,
				       dns_dispatch_t **dispp);
static isc_boolean_t destroy_mgr_ok(dns_dispatchmgr_t *mgr);
static void destroy_mgr(dns_dispatchmgr_t **mgrp);
static isc_result_t qid_allocate(dns_dispatchmgr_t *mgr, unsigned int buckets,
				 unsigned int increment, dns_qid_t **qidp);
static void qid_destroy(isc_mem_t *mctx, dns_qid_t **qidp);

#define LVL(x) ISC_LOG_DEBUG(x)

static void
mgr_log(dns_dispatchmgr_t *mgr, int level, const char *fmt, ...)
     ISC_FORMAT_PRINTF(3, 4);

static void
mgr_log(dns_dispatchmgr_t *mgr, int level, const char *fmt, ...) {
	char msgbuf[2048];
	va_list ap;

	if (! isc_log_wouldlog(dns_lctx, level))
		return;

	va_start(ap, fmt);
	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
	va_end(ap);

	isc_log_write(dns_lctx,
		      DNS_LOGCATEGORY_DISPATCH, DNS_LOGMODULE_DISPATCH,
		      level, "dispatchmgr %p: %s", mgr, msgbuf);
}

static void
dispatch_log(dns_dispatch_t *disp, int level, const char *fmt, ...)
     ISC_FORMAT_PRINTF(3, 4);

static void
dispatch_log(dns_dispatch_t *disp, int level, const char *fmt, ...) {
	char msgbuf[2048];
	va_list ap;

	if (! isc_log_wouldlog(dns_lctx, level))
		return;

	va_start(ap, fmt);
	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
	va_end(ap);

	isc_log_write(dns_lctx,
		      DNS_LOGCATEGORY_DISPATCH, DNS_LOGMODULE_DISPATCH,
		      level, "dispatch %p: %s", disp, msgbuf);
}

static void
request_log(dns_dispatch_t *disp, dns_dispentry_t *resp,
	    int level, const char *fmt, ...)
     ISC_FORMAT_PRINTF(4, 5);

static void
request_log(dns_dispatch_t *disp, dns_dispentry_t *resp,
	    int level, const char *fmt, ...)
{
	char msgbuf[2048];
	char peerbuf[256];
	va_list ap;

	if (! isc_log_wouldlog(dns_lctx, level))
		return;

	va_start(ap, fmt);
	vsnprintf(msgbuf, sizeof(msgbuf), fmt, ap);
	va_end(ap);

	if (VALID_RESPONSE(resp)) {
		isc_sockaddr_format(&resp->host, peerbuf, sizeof(peerbuf));
		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DISPATCH,
			      DNS_LOGMODULE_DISPATCH, level,
			      "dispatch %p response %p %s: %s", disp, resp,
			      peerbuf, msgbuf);
	} else {
		isc_log_write(dns_lctx, DNS_LOGCATEGORY_DISPATCH,
			      DNS_LOGMODULE_DISPATCH, level,
			      "dispatch %p req/resp %p: %s", disp, resp,
			      msgbuf);
	}
}

static void
reseed_lfsr(isc_lfsr_t *lfsr, void *arg)
{
	dns_dispatchmgr_t *mgr = arg;
	isc_result_t result;
	isc_uint32_t val;

	REQUIRE(VALID_DISPATCHMGR(mgr));

	if (mgr->entropy != NULL) {
		result = isc_entropy_getdata(mgr->entropy, &val, sizeof(val),
					     NULL, 0);
		INSIST(result == ISC_R_SUCCESS);
		lfsr->count = (val & 0x1f) + 32;
		lfsr->state = val;
		return;
	}

	lfsr->count = (random() & 0x1f) + 32;	/* From 32 to 63 states */
	lfsr->state = random();
}

/*
 * Return an unpredictable message ID.
 */
static dns_messageid_t
dns_randomid(dns_qid_t *qid) {
	isc_uint32_t id;

	id = isc_lfsr_generate32(&qid->qid_lfsr1, &qid->qid_lfsr2);

	return (dns_messageid_t)(id & 0xFFFF);
}

/*
 * Return a hash of the destination and message id.
 */
static isc_uint32_t
dns_hash(dns_qid_t *qid, isc_sockaddr_t *dest, dns_messageid_t id) {
	unsigned int ret;

	ret = isc_sockaddr_hash(dest, ISC_TRUE);
	ret ^= id;
	ret %= qid->qid_nbuckets;

	INSIST(ret < qid->qid_nbuckets);

	return (ret);
}

/*
 * Find the first entry in 'qid'.  Returns NULL if there are no entries.
 */
static dns_dispentry_t *
linear_first(dns_qid_t *qid) {
	dns_dispentry_t *ret;
	unsigned int bucket;

	bucket = 0;

	while (bucket < qid->qid_nbuckets) {
		ret = ISC_LIST_HEAD(qid->qid_table[bucket]);
		if (ret != NULL)
			return (ret);
		bucket++;
	}

	return (NULL);
}

/*
 * Find the next entry after 'resp' in 'qid'.  Return NULL if there are
 * no more entries.
 */
static dns_dispentry_t *
linear_next(dns_qid_t *qid, dns_dispentry_t *resp) {
	dns_dispentry_t *ret;
	unsigned int bucket;

	ret = ISC_LIST_NEXT(resp, link);
	if (ret != NULL)
		return (ret);

	bucket = resp->bucket;
	bucket++;
	while (bucket < qid->qid_nbuckets) {
		ret = ISC_LIST_HEAD(qid->qid_table[bucket]);
		if (ret != NULL)
			return (ret);
		bucket++;
	}

	return (NULL);
}

/*
 * The dispatch must be locked.
 */
static isc_boolean_t
destroy_disp_ok(dns_dispatch_t *disp)
{
	if (disp->refcount != 0)
		return (ISC_FALSE);

	if (disp->recv_pending != 0)
		return (ISC_FALSE);

	if (disp->shutting_down == 0)
		return (ISC_FALSE);

	return (ISC_TRUE);
}


/*
 * Called when refcount reaches 0 (and safe to destroy).
 *
 * The dispatcher must not be locked.
 * The manager must be locked.
 */
static void
destroy_disp(isc_task_t *task, isc_event_t *event) {
	dns_dispatch_t *disp;
	dns_dispatchmgr_t *mgr;
	isc_boolean_t killmgr;

	INSIST(event->ev_type == DNS_EVENT_DISPATCHCONTROL);

	UNUSED(task);

	disp = event->ev_arg;
	mgr = disp->mgr;

	LOCK(&mgr->lock);
	ISC_LIST_UNLINK(mgr->list, disp, link);

	dispatch_log(disp, LVL(90),
		     "shutting down; detaching from sock %p, task %p",
		     disp->socket, disp->task);

	isc_socket_detach(&disp->socket);
	isc_task_detach(&disp->task);
	isc_event_free(&event);

	dispatch_free(&disp);

	killmgr = destroy_mgr_ok(mgr);
	UNLOCK(&mgr->lock);
	if (killmgr)
		destroy_mgr(&mgr);
}


/*
 * Find an entry for query ID 'id' and socket address 'dest' in 'qid'.
 * Return NULL if no such entry exists.
 */
static dns_dispentry_t *
bucket_search(dns_qid_t *qid, isc_sockaddr_t *dest, dns_messageid_t id,
	      unsigned int bucket)
{
	dns_dispentry_t *res;

	REQUIRE(bucket < qid->qid_nbuckets);

	res = ISC_LIST_HEAD(qid->qid_table[bucket]);

	while (res != NULL) {
		if ((res->id == id) && isc_sockaddr_equal(dest, &res->host))
			return (res);
		res = ISC_LIST_NEXT(res, link);
	}

	return (NULL);
}

static void
free_buffer(dns_dispatch_t *disp, void *buf, unsigned int len) {
	INSIST(buf != NULL && len != 0);


	switch (disp->socktype) {
	case isc_sockettype_tcp:
		INSIST(disp->tcpbuffers > 0);
		disp->tcpbuffers--;
		isc_mem_put(disp->mgr->mctx, buf, len);
		break;
	case isc_sockettype_udp:
		LOCK(&disp->mgr->buffer_lock);
		INSIST(disp->mgr->buffers > 0);
		INSIST(len == disp->mgr->buffersize);
		disp->mgr->buffers--;
		isc_mempool_put(disp->mgr->bpool, buf);
		UNLOCK(&disp->mgr->buffer_lock);
		break;
	default:
		INSIST(0);
		break;
	}
}

static void *
allocate_udp_buffer(dns_dispatch_t *disp) {
	void *temp;

	LOCK(&disp->mgr->buffer_lock);
	temp = isc_mempool_get(disp->mgr->bpool);

	if (temp != NULL)
		disp->mgr->buffers++;
	UNLOCK(&disp->mgr->buffer_lock);

	return (temp);
}

static inline void
free_event(dns_dispatch_t *disp, dns_dispatchevent_t *ev) {
	if (disp->failsafe_ev == ev) {
		INSIST(disp->shutdown_out == 1);
		disp->shutdown_out = 0;

		return;
	}

	isc_mempool_put(disp->mgr->epool, ev);
}

static inline dns_dispatchevent_t *
allocate_event(dns_dispatch_t *disp) {
	dns_dispatchevent_t *ev;

	ev = isc_mempool_get(disp->mgr->epool);
	if (ev == NULL)
		return (NULL);
	ISC_EVENT_INIT(ev, sizeof(*ev), 0, NULL, 0,
		       NULL, NULL, NULL, NULL, NULL);

	return (ev);
}

/*
 * General flow:
 *
 * If I/O result == CANCELED or error, free the buffer.
 *
 * If query, free the buffer, restart.
 *
 * If response:
 *	Allocate event, fill in details.
 *		If cannot allocate, free buffer, restart.
 *	find target.  If not found, free buffer, restart.
 *	if event queue is not empty, queue.  else, send.
 *	restart.
 */
static void
udp_recv(isc_task_t *task, isc_event_t *ev_in) {
	isc_socketevent_t *ev = (isc_socketevent_t *)ev_in;
	dns_dispatch_t *disp = ev_in->ev_arg;
	dns_messageid_t id;
	isc_result_t dres;
	isc_buffer_t source;
	unsigned int flags;
	dns_dispentry_t *resp;
	dns_dispatchevent_t *rev;
	unsigned int bucket;
	isc_boolean_t killit;
	isc_boolean_t queue_response;
	dns_dispatchmgr_t *mgr;
	dns_qid_t *qid;
	isc_netaddr_t netaddr;
	int match;

	UNUSED(task);

	LOCK(&disp->lock);

	mgr = disp->mgr;
	qid = mgr->qid;

	dispatch_log(disp, LVL(90),
		     "got packet: requests %d, buffers %d, recvs %d",
		     disp->requests, disp->mgr->buffers, disp->recv_pending);

	if (ev->ev_type == ISC_SOCKEVENT_RECVDONE) {
		/*
		 * Unless the receive event was imported from a listening
		 * interface, in which case the event type is
		 * DNS_EVENT_IMPORTRECVDONE, receive operation must be pending.
		 */
		INSIST(disp->recv_pending != 0);