lib/dns/adb.c

	adb.c revision 86944a4c8002e80ae9b6eb5a5e29b797879be45f
/*
 * Copyright (C) 1999  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.
 */

/*
 * Implementation notes
 * --------------------
 *
 * In handles, if task == NULL, no events will be generated, and no events
 * have been sent.  If task != NULL but taskaction == NULL, an event has been
 * posted but not yet freed.  If neigher are NULL, no event was posted.
 *
 */

#include <config.h>

#include <stdio.h>
#include <string.h>

#include <isc/assertions.h>
#include <isc/condition.h>
#include <isc/magic.h>
#include <isc/mutex.h>
#include <isc/mutexblock.h>
#include <isc/event.h>

#include <dns/address.h>
#include <dns/events.h>
#include <dns/name.h>
#include <dns/rdata.h>
#include <dns/rdataset.h>
#include <dns/view.h>

#include "../isc/util.h"

#define DNS_ADB_MAGIC         0x44616462    /* Dadb. */
#define DNS_ADB_VALID(x)      ISC_MAGIC_VALID(x, DNS_ADB_MAGIC)
#define DNS_ADBNAME_MAGIC     0x6164624e    /* adbN. */
#define DNS_ADBNAME_VALID(x)      ISC_MAGIC_VALID(x, DNS_ADBNAME_MAGIC)
#define DNS_ADBNAMEHOOK_MAGIC     0x61644e48    /* adNH. */
#define DNS_ADBNAMEHOOK_VALID(x)  ISC_MAGIC_VALID(x, DNS_ADBNAMEHOOK_MAGIC)
#define DNS_ADBZONEINFO_MAGIC     0x6164625a    /* adbZ. */
#define DNS_ADBZONEINFO_VALID(x)  ISC_MAGIC_VALID(x, DNS_ADBZONEINFO_MAGIC)
#define DNS_ADBENTRY_MAGIC    0x61646245    /* adbE. */
#define DNS_ADBENTRY_VALID(x)     ISC_MAGIC_VALID(x, DNS_ADBENTRY_MAGIC)

/*
 * Lengths of lists needs to be powers of two.
 */
#define DNS_ADBNAMELIST_LENGTH  16  /* how many buckets for names */
#define DNS_ADBENTRYLIST_LENGTH 16  /* how many buckets for addresses */

#define FREE_ITEMS      16  /* free count for memory pools */
#define FILL_COUNT       8  /* fill count for memory pools */

#define DNS_ADB_INVALIDBUCKET (-1)  /* invalid bucket address */

typedef ISC_LIST(dns_adbname_t) dns_adbnamelist_t;
typedef struct dns_adbnamehook dns_adbnamehook_t;
typedef struct dns_adbzoneinfo dns_adbzoneinfo_t;
typedef ISC_LIST(dns_adbentry_t) dns_adbentrylist_t;

struct dns_adb {
    unsigned int            magic;

    isc_mutex_t         lock;
    isc_condition_t         shutdown_cond;
    isc_mem_t              *mctx;
    dns_view_t             *view;

    unsigned int            refcnt;

    isc_mutex_t         mplock;
    isc_mempool_t              *nmp;    /* dns_adbname_t */
    isc_mempool_t              *nhmp;   /* dns_adbnamehook_t */
    isc_mempool_t              *zimp;   /* dns_adbzoneinfo_t */
    isc_mempool_t              *emp;    /* dns_adbentry_t */
    isc_mempool_t              *ahmp;   /* dns_adbhandle_t */
    isc_mempool_t              *aimp;   /* dns_adbaddrinfo_t */

    /*
     * Bucketized locks and lists for names.
     */
    dns_adbnamelist_t       names[DNS_ADBNAMELIST_LENGTH];
    isc_mutex_t         namelocks[DNS_ADBNAMELIST_LENGTH];

    /*
     * Bucketized locks for entries.
     */
    dns_adbentrylist_t      entries[DNS_ADBENTRYLIST_LENGTH];
    isc_mutex_t         entrylocks[DNS_ADBENTRYLIST_LENGTH];
};

struct dns_adbname {
    unsigned int            magic;
    dns_name_t          name;
    ISC_LIST(dns_adbnamehook_t) namehooks;
    ISC_LIST(dns_adbnamehook_t) in_progress;
    ISC_LIST(dns_adbhandle_t)   handles;
    ISC_LINK(dns_adbname_t)     link;
};

/*
 * dns_adbnamehook_t
 *
 * This is a small widget that dangles off a dns_adbname_t.  It contains a
 * pointer to the address information about this host, and a link to the next
 * namehook that will contain the next address this host has.
 */
struct dns_adbnamehook {
    unsigned int            magic;
    dns_adbentry_t             *entry;
    ISC_LINK(dns_adbnamehook_t) link;
};

/*
 * dns_adbzoneinfo_t
 *
 * This is a small widget that holds zone-specific information about an
 * address.  Currently limited to lameness, but could just as easily be
 * extended to other types of information about zones.
 */
struct dns_adbzoneinfo {
    unsigned int            magic;

    dns_name_t          zone;
    unsigned int            lame_timer;

    ISC_LINK(dns_adbzoneinfo_t) link;
};

/*
 * An address entry.  It holds quite a bit of information about addresses,
 * including edns state, rtt, and of course the address of the host.
 */
struct dns_adbentry {
    unsigned int            magic;

    int             lock_bucket;
    unsigned int            refcnt;

    unsigned int            flags;
    int             goodness;   /* bad <= 0 < good */
    unsigned int            srtt;
    isc_sockaddr_t          sockaddr;

    ISC_LIST(dns_adbzoneinfo_t) zoneinfo;
    ISC_LINK(dns_adbentry_t)    link;
};

/*
 * Internal functions (and prototypes).
 */
static inline dns_adbname_t *new_adbname(dns_adb_t *);
static inline void free_adbname(dns_adb_t *, dns_adbname_t **);
static inline dns_adbnamehook_t *new_adbnamehook(dns_adb_t *,
                         dns_adbentry_t *);
static inline void free_adbnamehook(dns_adb_t *, dns_adbnamehook_t **);
static inline dns_adbzoneinfo_t *new_adbzoneinfo(dns_adb_t *);
static inline void free_adbzoneinfo(dns_adb_t *, dns_adbzoneinfo_t **);
static inline dns_adbentry_t *new_adbentry(dns_adb_t *);
static inline void free_adbentry(dns_adb_t *, dns_adbentry_t **);
static inline dns_adbhandle_t *new_adbhandle(dns_adb_t *);
static inline void free_adbhandle(dns_adb_t *, dns_adbhandle_t **);
static inline dns_adbaddrinfo_t *new_adbaddrinfo(dns_adb_t *,
                         dns_adbentry_t *);

static inline dns_adbname_t *find_name_and_lock(dns_adb_t *, dns_name_t *,
                        int *);
static inline dns_adbentry_t *find_entry_and_lock(dns_adb_t *,
                          isc_sockaddr_t *, int *);
static void print_dns_name(FILE *, dns_name_t *);
static void print_namehook_list(FILE *, dns_adbname_t *);
static void print_handle_list(FILE *, dns_adbname_t *);
static inline void inc_adb_refcnt(dns_adb_t *, isc_boolean_t);
static inline void dec_adb_refcnt(dns_adb_t *, isc_boolean_t);
static inline void inc_entry_refcnt(dns_adb_t *, dns_adbentry_t *,
                    isc_boolean_t);
static inline void dec_entry_refcnt(dns_adb_t *, dns_adbentry_t *,
                    isc_boolean_t);

static inline void
inc_adb_refcnt(dns_adb_t *adb, isc_boolean_t lock)
{
    if (lock)
        LOCK(&adb->lock);

    adb->refcnt++;

    if (lock)
        UNLOCK(&adb->lock);
}

static inline void
dec_adb_refcnt(dns_adb_t *adb, isc_boolean_t lock)
{
    if (lock)
        LOCK(&adb->lock);

    INSIST(adb->refcnt > 0);
    adb->refcnt--;

    if (adb->refcnt == 0)
        SIGNAL(&adb->shutdown_cond);

    if (lock)
        UNLOCK(&adb->lock);
}

static inline void
inc_entry_refcnt(dns_adb_t *adb, dns_adbentry_t *entry, isc_boolean_t lock)
{
    int bucket;

    bucket = entry->lock_bucket;

    if (lock)
        LOCK(&adb->entrylocks[bucket]);

    entry->refcnt++;

    if (lock)
        UNLOCK(&adb->entrylocks[bucket]);
}

static inline void
dec_entry_refcnt(dns_adb_t *adb, dns_adbentry_t *entry, isc_boolean_t lock)
{
    int bucket;
    isc_boolean_t destroy_entry;
    dns_adbzoneinfo_t *zi;

    bucket = entry->lock_bucket;

    if (lock)
        LOCK(&adb->entrylocks[bucket]);

    INSIST(entry->refcnt > 0);
    entry->refcnt--;

    destroy_entry = ISC_FALSE;
    if (entry->refcnt == 0) {
        destroy_entry = ISC_TRUE;
        ISC_LIST_UNLINK(adb->entries[bucket], entry, link);
    }

    if (lock)
        UNLOCK(&adb->entrylocks[bucket]);

    if (!destroy_entry)
        return;

    entry->lock_bucket = DNS_ADB_INVALIDBUCKET;
    zi = ISC_LIST_HEAD(entry->zoneinfo);
    while (zi != NULL) {
        ISC_LIST_UNLINK(entry->zoneinfo, zi, link);
        free_adbzoneinfo(adb, &zi);
        zi = ISC_LIST_HEAD(entry->zoneinfo);
    }

    free_adbentry(adb, &entry);
}

static inline dns_adbname_t *
new_adbname(dns_adb_t *adb)
{
    dns_adbname_t *name;

    name = isc_mempool_get(adb->nmp);
    if (name == NULL)
        return (NULL);

    name->magic = DNS_ADBNAME_MAGIC;
    dns_name_init(&name->name, NULL);
    ISC_LIST_INIT(name->namehooks);
    ISC_LIST_INIT(name->in_progress);
    ISC_LIST_INIT(name->handles);
    ISC_LINK_INIT(name, link);

    return (name);
}

static inline void
free_adbname(dns_adb_t *adb, dns_adbname_t **name)
{
    dns_adbname_t *n;

    INSIST(name != NULL && DNS_ADBNAME_VALID(*name));
    n = *name;
    *name = NULL;

    INSIST(ISC_LIST_EMPTY(n->namehooks));
    INSIST(ISC_LIST_EMPTY(n->in_progress));
    INSIST(ISC_LIST_EMPTY(n->handles));
    INSIST(!ISC_LINK_LINKED(n, link));

    n->magic = 0;
    dns_name_free(&n->name, adb->mctx);

    isc_mempool_put(adb->nmp, n);
}

static inline dns_adbnamehook_t *
new_adbnamehook(dns_adb_t *adb, dns_adbentry_t *entry)
{
    dns_adbnamehook_t *nh;

    nh = isc_mempool_get(adb->nhmp);
    if (nh == NULL)
        return (NULL);

    nh->magic = DNS_ADBNAMEHOOK_MAGIC;
    nh->entry = entry;
    ISC_LINK_INIT(nh, link);

    return (nh);
}

static inline void
free_adbnamehook(dns_adb_t *adb, dns_adbnamehook_t **namehook)
{
    dns_adbnamehook_t *nh;

    INSIST(namehook != NULL && DNS_ADBNAMEHOOK_VALID(*namehook));
    nh = *namehook;
    *namehook = NULL;

    INSIST(nh->entry == NULL);
    INSIST(!ISC_LINK_LINKED(nh, link));

    nh->magic = 0;
    isc_mempool_put(adb->nhmp, nh);
}

static inline dns_adbzoneinfo_t *
new_adbzoneinfo(dns_adb_t *adb)
{
    dns_adbzoneinfo_t *zi;

    zi = isc_mempool_get(adb->zimp);
    if (zi == NULL)
        return (NULL);

    zi->magic = DNS_ADBZONEINFO_MAGIC;
    dns_name_init(&zi->zone, NULL);
    zi->lame_timer = 0;
    ISC_LINK_INIT(zi, link);

    return (zi);
}

static inline void
free_adbzoneinfo(dns_adb_t *adb, dns_adbzoneinfo_t **zoneinfo)
{
    dns_adbzoneinfo_t *zi;

    INSIST(zoneinfo != NULL && DNS_ADBZONEINFO_VALID(*zoneinfo));
    zi = *zoneinfo;
    *zoneinfo = NULL;

    INSIST(!ISC_LINK_LINKED(zi, link));

    dns_name_free(&zi->zone, adb->mctx);

    zi->magic = 0;

    isc_mempool_put(adb->zimp, zi);
}

static inline dns_adbentry_t *
new_adbentry(dns_adb_t *adb)
{
    dns_adbentry_t *e;

    e = isc_mempool_get(adb->emp);
    if (e == NULL)
        return (NULL);

    e->magic = DNS_ADBENTRY_MAGIC;
    e->lock_bucket = DNS_ADB_INVALIDBUCKET;
    e->refcnt = 0;
    e->flags = 0;
    e->goodness = 0;
    e->srtt = 0;
    ISC_LIST_INIT(e->zoneinfo);
    ISC_LINK_INIT(e, link);

    return (e);
}

static inline void
free_adbentry(dns_adb_t *adb, dns_adbentry_t **entry)
{
    dns_adbentry_t *e;

    INSIST(entry != NULL && DNS_ADBENTRY_VALID(*entry));
    e = *entry;
    *entry = NULL;

    INSIST(e->lock_bucket == DNS_ADB_INVALIDBUCKET);
    INSIST(e->refcnt == 0);
    INSIST(ISC_LIST_EMPTY(e->zoneinfo));
    INSIST(!ISC_LINK_LINKED(e, link));

    e->magic = 0;
    isc_mempool_put(adb->emp, e);
}

static inline dns_adbhandle_t *
new_adbhandle(dns_adb_t *adb)
{
    dns_adbhandle_t *h;
    isc_result_t result;

    h = isc_mempool_get(adb->ahmp);
    if (h == NULL)
        return (NULL);

    /*
     * public members
     */
    h->magic = 0;
    h->query_pending = ISC_FALSE;
    h->result = ISC_R_UNEXPECTED;
    ISC_LIST_INIT(h->list);
    ISC_LINK_INIT(h, next);
    h->name_bucket = DNS_ADB_INVALIDBUCKET;
    h->adbname = NULL;

    /*
     * private members
     */
    result = isc_mutex_init(&h->lock);
    if (result != ISC_R_SUCCESS) {
        UNEXPECTED_ERROR(__FILE__, __LINE__,
                 "isc_mutex_init failed in new_adbhandle()");
        isc_mempool_put(adb->ahmp, h);
        return (NULL);
    }
    ISC_LINK_INIT(h, link);

    ISC_EVENT_INIT(&h->event, sizeof (isc_event_t), 0, 0, 0, NULL, NULL,
               NULL, NULL, h);

    h->magic = DNS_ADBHANDLE_MAGIC;
    return (h);
}

static inline void
free_adbhandle(dns_adb_t *adb, dns_adbhandle_t **handlep)
{
    dns_adbhandle_t *handle;

    INSIST(handlep != NULL && DNS_ADBHANDLE_VALID(*handlep));
    handle = *handlep;
    *handlep = NULL;

    INSIST(ISC_LIST_EMPTY(handle->list));
    INSIST(!ISC_LINK_LINKED(handle, next));
    INSIST(!ISC_LINK_LINKED(handle, link));
    INSIST(handle->name_bucket == DNS_ADB_INVALIDBUCKET);
    INSIST(handle->adbname == NULL);

    handle->magic = 0;

    isc_mutex_destroy(&handle->lock);
    isc_mempool_put(adb->ahmp, handle);
}

/*
 * Copy bits from the entry into the newly allocated addrinfo.  The entry
 * must be locked, and the reference count must be bumped up by one
 * if this function returns a valid pointer.
 */
static inline dns_adbaddrinfo_t *
new_adbaddrinfo(dns_adb_t *adb, dns_adbentry_t *entry)
{
    dns_adbaddrinfo_t *ai;

    ai = isc_mempool_get(adb->aimp);
    if (ai == NULL)
        return (NULL);

    ai->magic = DNS_ADBADDRINFO_MAGIC;
    ai->sockaddr = &entry->sockaddr;
    ai->goodness = entry->goodness;
    ai->srtt = entry->srtt;
    ai->flags = entry->flags;
    ai->entry = entry;
    ISC_LINK_INIT(ai, link);

    return (ai);
}

static inline void
free_adbaddrinfo(dns_adb_t *adb, dns_adbaddrinfo_t **ainfo)
{
    dns_adbaddrinfo_t *ai;

    INSIST(ainfo != NULL && DNS_ADBADDRINFO_VALID(*ainfo));
    ai = *ainfo;
    *ainfo = NULL;

    INSIST(ai->sockaddr == NULL);
    INSIST(ai->entry == NULL);
    INSIST(!ISC_LINK_LINKED(ai, link));

    ai->magic = 0;

    isc_mempool_put(adb->aimp, ai);
}

/*
 * Search for the name.  NOTE:  The bucket is kept locked on both
 * success and failure, so it must always be unlocked by the caller!
 *
 * On the first call to this function, *bucketp must be set to
 * DNS_ADB_INVALIDBUCKET.
 */
static inline dns_adbname_t *
find_name_and_lock(dns_adb_t *adb, dns_name_t *name, int *bucketp)
{
    dns_adbname_t *adbname;
    int bucket;

    bucket = dns_name_hash(name, ISC_FALSE);
    bucket &= (DNS_ADBNAMELIST_LENGTH - 1);

    if (*bucketp == DNS_ADB_INVALIDBUCKET) {
        LOCK(&adb->namelocks[bucket]);
        *bucketp = bucket;
    } else if (*bucketp != bucket) {
        UNLOCK(&adb->namelocks[*bucketp]);
        LOCK(&adb->namelocks[bucket]);
        *bucketp = bucket;
    }

    adbname = ISC_LIST_HEAD(adb->names[bucket]);
    while (adbname != NULL) {
        if (dns_name_equal(name, &adbname->name))
            return (adbname);
        adbname = ISC_LIST_NEXT(adbname, link);
    }

    return (NULL);
}

/*
 * Search for the address.  NOTE:  The bucket is kept locked on both
 * success and failure, so it must always be unlocked by the caller.
 *
 * On the first call to this function, *bucketp must be set to
 * DNS_ADB_INVALIDBUCKET.  This will cause a lock to occur.  On
 * later calls (within the same "lock path") it can be left alone, so
 * if this function is called multiple times locking is only done if
 * the bucket changes.
 */
static inline dns_adbentry_t *
find_entry_and_lock(dns_adb_t *adb, isc_sockaddr_t *addr, int *bucketp)
{
    dns_adbentry_t *entry;
    int bucket;

    bucket = isc_sockaddr_hash(addr, ISC_TRUE);
    bucket &= (DNS_ADBENTRYLIST_LENGTH - 1);

    if (*bucketp == DNS_ADB_INVALIDBUCKET) {
        LOCK(&adb->entrylocks[bucket]);
        *bucketp = bucket;
    } else if (*bucketp != bucket) {
        UNLOCK(&adb->entrylocks[*bucketp]);
        LOCK(&adb->entrylocks[bucket]);
        *bucketp = bucket;
    }

    entry = ISC_LIST_HEAD(adb->entries[bucket]);
    while (entry != NULL) {
        if (isc_sockaddr_equal(addr, &entry->sockaddr))
            return (entry);
        entry = ISC_LIST_NEXT(entry, link);
    }

    return (NULL);
}

static void
copy_namehook_list(dns_adb_t *adb, dns_adbhandle_t *handle,
           dns_adbname_t *name)
{
    dns_adbnamehook_t *namehook;
    dns_adbaddrinfo_t *addrinfo;

    handle->query_pending = ISC_FALSE;
    handle->result = ISC_R_UNEXPECTED;

    namehook = ISC_LIST_HEAD(name->namehooks);
    while (namehook != NULL) {
        if (namehook->entry->lock_bucket == DNS_ADB_INVALIDBUCKET) {
            handle->query_pending = ISC_TRUE;
        } else {
            /* XXX check for expired entries, zoneinfo */
            addrinfo = new_adbaddrinfo(adb, namehook->entry);
            if (addrinfo == NULL) {
                handle->result = ISC_R_NOMEMORY;
                return;
            }
            /*
             * Found a valid entry.  Add it to the handle's list.
             */
            inc_entry_refcnt(adb, namehook->entry, ISC_TRUE);
            ISC_LIST_APPEND(handle->list, addrinfo, link);
        }

        namehook = ISC_LIST_NEXT(namehook, link);
    }

    handle->result = ISC_R_SUCCESS; /* all were copied */
}

static void
destroy(dns_adb_t *adb)
{
    adb->magic = 0;

    isc_mempool_destroy(&adb->nmp);
    isc_mempool_destroy(&adb->nhmp);
    isc_mempool_destroy(&adb->zimp);
    isc_mempool_destroy(&adb->emp);
    isc_mempool_destroy(&adb->ahmp);
    isc_mempool_destroy(&adb->aimp);

    isc_mutexblock_destroy(adb->entrylocks, DNS_ADBENTRYLIST_LENGTH);
    isc_mutexblock_destroy(adb->namelocks, DNS_ADBNAMELIST_LENGTH);

    isc_mutex_destroy(&adb->lock);
    isc_mutex_destroy(&adb->mplock);

    isc_mem_put(adb->mctx, adb, sizeof (dns_adb_t));
}


/*
 * Public functions.
 */

isc_result_t
dns_adb_create(isc_mem_t *mem, dns_view_t *view, dns_adb_t **newadb)
{
    dns_adb_t *adb;
    isc_result_t result;
    int i;

    REQUIRE(mem != NULL);
    REQUIRE(newadb != NULL && *newadb == NULL);

    adb = isc_mem_get(mem, sizeof (dns_adb_t));
    if (adb == NULL)
        return (ISC_R_NOMEMORY);

    /*
     * Initialize things here that cannot fail, and especially things
     * that must be NULL for the error return to work properly.
     */
    adb->magic = 0;
    adb->refcnt = 1;
    adb->nmp = NULL;
    adb->nhmp = NULL;
    adb->zimp = NULL;
    adb->emp = NULL;
    adb->ahmp = NULL;
    adb->aimp = NULL;

    result = isc_mutex_init(&adb->lock);
    if (result != ISC_R_SUCCESS)
        goto fail0a;
    result = isc_mutex_init(&adb->mplock);
    if (result != ISC_R_SUCCESS)
        goto fail0b;
    result = isc_condition_init(&adb->shutdown_cond);
    if (result != ISC_R_SUCCESS)
        goto fail0c;

    /*
     * Initialize the bucket locks for names and elements.
     * May as well initialize the list heads, too.
     */
    result = isc_mutexblock_init(adb->namelocks, DNS_ADBNAMELIST_LENGTH);
    if (result != ISC_R_SUCCESS)
        goto fail1;
    for (i = 0 ; i < DNS_ADBNAMELIST_LENGTH ; i++)
        ISC_LIST_INIT(adb->names[i]);
    for (i = 0 ; i < DNS_ADBENTRYLIST_LENGTH ; i++)
        ISC_LIST_INIT(adb->entries[i]);
    result = isc_mutexblock_init(adb->entrylocks, DNS_ADBENTRYLIST_LENGTH);
    if (result != ISC_R_SUCCESS)
        goto fail2;

    /*
     * Memory pools
     */
#define MPINIT(t, p, l) do { \
    result = isc_mempool_create(mem, sizeof (t), &(p)); \
    if (result != ISC_R_SUCCESS) \
        goto fail3; \
    isc_mempool_setfreemax((p), FREE_ITEMS); \
    isc_mempool_setfillcount((p), FILL_COUNT); \
    if (l) \
        isc_mempool_associatelock((p), &adb->mplock); \
} while (0)

    MPINIT(dns_adbname_t,       adb->nmp,   ISC_TRUE);
    MPINIT(dns_adbnamehook_t,   adb->nhmp,  ISC_TRUE);
    MPINIT(dns_adbzoneinfo_t,   adb->zimp,  ISC_TRUE);
    MPINIT(dns_adbentry_t,      adb->emp,   ISC_TRUE);
    MPINIT(dns_adbhandle_t,     adb->ahmp,  ISC_TRUE);
    MPINIT(dns_adbaddrinfo_t,   adb->aimp,  ISC_TRUE);

#undef MPINIT

    /*
     * Normal return.
     */
    adb->mctx = mem;
    adb->view = view;
    adb->magic = DNS_ADB_MAGIC;
    *newadb = adb;
    return (ISC_R_SUCCESS);

 fail3: /* clean up entrylocks */
    isc_mutexblock_destroy(adb->entrylocks, DNS_ADBENTRYLIST_LENGTH);

 fail2: /* clean up namelocks */
    isc_mutexblock_destroy(adb->namelocks, DNS_ADBNAMELIST_LENGTH);

 fail1: /* clean up only allocated memory */
    if (adb->nmp != NULL)
        isc_mempool_destroy(&adb->nmp);
    if (adb->nhmp != NULL)
        isc_mempool_destroy(&adb->nhmp);
    if (adb->zimp != NULL)
        isc_mempool_destroy(&adb->zimp);
    if (adb->emp != NULL)
        isc_mempool_destroy(&adb->emp);
    if (adb->ahmp != NULL)
        isc_mempool_destroy(&adb->ahmp);
    if (adb->aimp != NULL)
        isc_mempool_destroy(&adb->aimp);

    isc_condition_destroy(&adb->shutdown_cond);
 fail0c:
    isc_mutex_destroy(&adb->mplock);
 fail0b:
    isc_mutex_destroy(&adb->lock);
 fail0a:
    isc_mem_put(mem, adb, sizeof (dns_adb_t));

    return (result);
}

void
dns_adb_destroy(dns_adb_t **adbx)
{
    dns_adb_t *adb;
    isc_boolean_t done;

    REQUIRE(adbx != NULL && DNS_ADB_VALID(*adbx));

    adb = *adbx;
    *adbx = NULL;

    /*
     * If all lists are empty, destroy the memory used by this
     * adb.
     */
    LOCK(&adb->lock);
    dec_adb_refcnt(adb, ISC_FALSE);
    do {
        done = ISC_TRUE;
        if (adb->refcnt != 0)
            done = ISC_FALSE;

        if (!done)
            WAIT(&adb->shutdown_cond, &adb->lock);
    } while (!done);
    UNLOCK(&adb->lock);

    destroy(adb);
}

isc_result_t
dns_adb_lookup(dns_adb_t *adb, isc_task_t *task, isc_taskaction_t action,
           void *arg, dns_name_t *name, dns_name_t *zone,
           dns_adbhandle_t **handlep)
{
    dns_adbhandle_t *handle;
    dns_adbname_t *adbname;
    int bucket;
    isc_result_t result;
    isc_boolean_t attach_to_task;

    REQUIRE(DNS_ADB_VALID(adb));
    if (task != NULL) {
        REQUIRE(action != NULL);
    }
    REQUIRE(name != NULL);
    REQUIRE(zone != NULL);
    REQUIRE(handlep != NULL && *handlep == NULL);

    result = ISC_R_UNEXPECTED;
    attach_to_task = ISC_FALSE;

    /*
     * Look up the name in our internal database.
     *
     * Possibilities:  Note that these are not always exclusive.
     *
     *  No name found.  In this case, allocate a new name header and
     *  an initial namehook or two.  If any of these allocations
     *  fail, clean up and return ISC_R_NOMEMORY.
     *
     *  Name found, valid addresses present.  Allocate one addrinfo
     *  structure for each found and append it to the linked list
     *  of addresses for this header.
     *
     *  Name found, queries pending.  In this case, if a task was
     *  passed in, allocate a job id, attach it to the name's job
     *  list and remember to tell the caller that there will be
     *  more info coming later.
     */

    handle = new_adbhandle(adb);
    if (handle == NULL) {
        result = ISC_R_NOMEMORY;
        goto out;
    }

    /*
     * Look things up in our database first.
     */
    bucket = DNS_ADB_INVALIDBUCKET;
    adbname = find_name_and_lock(adb, name, &bucket);

    /*
     * Found!  Run through the name and copy out the bits we are
     * interested in.  If we cannot copy at least one address, return
     * ISC_R_NOMEMORY, otherwise copy out what we can and set the
     * missing_data bit in the header.
     */
    if (adbname != NULL) {
        copy_namehook_list(adb, handle, adbname);
        if (handle->result == ISC_R_NOMEMORY
            && ISC_LIST_EMPTY(handle->list)) {
            free_adbhandle(adb, &handle);
            result = ISC_R_NOMEMORY;
            goto out;
        }

        /*
         * Attach to the name's query list if there are queries
         * already running.
         */
        if (handle->query_pending && task != NULL) {
            handle->adbname = adbname;
            handle->name_bucket = bucket;
            ISC_LIST_APPEND(adbname->handles, handle, link);
            attach_to_task = ISC_TRUE;
        } else {
            /*
             * We are done with this name, so release the lock
             * here.  Then, lock the adb itself, and add the
             * handle to the list of handles given out.
             */
            UNLOCK(&adb->namelocks[bucket]);
            bucket = DNS_ADB_INVALIDBUCKET;
        }

        result = ISC_R_SUCCESS;
        goto out;
    }

    /*
     * Nothing found.  Allocate a new adbname structure for this name
     * and look in the database for details.  If the database has
     * nothing useful, start a fetch if we can.
     */

    /*
     * Temporary XXX
     */
    result = ISC_R_UNEXPECTED;
    free_adbhandle(adb, &handle);

 out:
    if (handle != NULL) {
        *handlep = handle;

        if (attach_to_task) {
            isc_task_t *taskp;

            taskp = NULL;
            isc_task_attach(task, &taskp);
            handle->event.sender = taskp;
            handle->event.action = action;
            handle->event.arg = arg;
        }
    }

    if (bucket != DNS_ADB_INVALIDBUCKET)
        UNLOCK(&adb->namelocks[bucket]);

    return (result);
}

isc_result_t
dns_adb_deletename(dns_adb_t *adb, dns_name_t *host)
{
    int name_bucket, addr_bucket;
    dns_adbname_t *name;
    dns_adbentry_t *entry;
    dns_adbnamehook_t *namehook;
    dns_adbhandle_t *handle;

    REQUIRE(DNS_ADB_VALID(adb));
    REQUIRE(host != NULL);

    name = NULL;
    entry = NULL;
    namehook = NULL;

    /*
     * Find the name.
     */
    name_bucket = DNS_ADB_INVALIDBUCKET;
    name = find_name_and_lock(adb, host, &name_bucket);
    if (name == NULL) {
        UNLOCK(&adb->namelocks[name_bucket]);
        return (ISC_R_NOTFOUND);
    }

    /*
     * If any handles are attached to this name, notify them that things
     * are going away by canceling their requests.
     */


    /* XXX
     * If fetches are running for this name, cancel them all.
     */
    handle = ISC_LIST_HEAD(name->handles);
    while (handle != NULL) {
        isc_event_t *ev;
        isc_task_t *task;

        LOCK(&handle->lock);

        ev = &handle->event;
        task = ev->sender;
        ev->sender = handle;
        ev->type = DNS_EVENT_ADBNAMEDELETED;
        isc_task_sendanddetach(&task, &ev);

        /*
         * Unlink the handle from the name, letting the caller
         * call dns_adb_done() on it to clean it up later.
         */
        ISC_LIST_UNLINK(name->handles, handle, link);
        handle->adbname = NULL;
        handle->name_bucket = DNS_ADB_INVALIDBUCKET;

        UNLOCK(&handle->lock);

        handle = ISC_LIST_HEAD(name->handles);
    }

    /*
     * Loop through the name and kill any namehooks and entries they
     * point to.
     */
    addr_bucket = DNS_ADB_INVALIDBUCKET;
    namehook = ISC_LIST_HEAD(name->namehooks);
    while (namehook != NULL) {
        INSIST(DNS_ADBNAMEHOOK_VALID(namehook));

        /*
         * Clean up the entry if needed.
         */
        entry = namehook->entry;
        if (entry != NULL) {
            INSIST(DNS_ADBENTRY_VALID(entry));

            if (addr_bucket != entry->lock_bucket) {
                if (addr_bucket != DNS_ADB_INVALIDBUCKET)
                    UNLOCK(&adb->entrylocks[addr_bucket]);
                addr_bucket = entry->lock_bucket;
                LOCK(&adb->entrylocks[addr_bucket]);
            }

            dec_entry_refcnt(adb, entry, ISC_FALSE);
        }

        /*
         * Free the namehook
         */
        namehook->entry = NULL;
        ISC_LIST_UNLINK(name->namehooks, namehook, link);
        free_adbnamehook(adb, &namehook);

        namehook = ISC_LIST_HEAD(name->namehooks);
    }

    /*
     * And lastly, unlink and free the name.
     */
    ISC_LIST_UNLINK(adb->names[name_bucket], name, link);
    free_adbname(adb, &name);

    if (name_bucket != DNS_ADB_INVALIDBUCKET)
        UNLOCK(&adb->namelocks[name_bucket]);
    if (addr_bucket != DNS_ADB_INVALIDBUCKET)
        UNLOCK(&adb->entrylocks[addr_bucket]);

    return (DNS_R_SUCCESS);
}

isc_result_t
dns_adb_insert(dns_adb_t *adb, dns_name_t *host, isc_sockaddr_t *addr)
{
    dns_adbname_t *name;
    isc_boolean_t free_name;
    dns_adbentry_t *entry;
    isc_boolean_t free_entry;
    dns_adbnamehook_t *namehook;
    isc_boolean_t free_namehook;
    isc_boolean_t decr_refcnt;
    int name_bucket, addr_bucket; /* unlock if != DNS_ADB_INVALIDBUCKET */
    isc_result_t result;

    REQUIRE(DNS_ADB_VALID(adb));
    REQUIRE(host != NULL);
    REQUIRE(addr != NULL);

    name = NULL;
    free_name = ISC_FALSE;
    entry = NULL;
    free_entry = ISC_FALSE;
    namehook = NULL;
    free_namehook = ISC_FALSE;
    decr_refcnt = ISC_FALSE;
    result = ISC_R_UNEXPECTED;

    /*
     * First, see if the host is already in the database.  If it is,
     * don't make a new host entry.  If not, copy the name and name's
     * contents into our structure and allocate what we'll need
     * to attach things together.
     */
    name_bucket = DNS_ADB_INVALIDBUCKET;
    name = find_name_and_lock(adb, host, &name_bucket);
    if (name == NULL) {
        name = new_adbname(adb);
        if (name == NULL) {
            result = ISC_R_NOMEMORY;
            goto out;
        }
        free_name = ISC_TRUE;
        result = dns_name_dup(host, adb->mctx, &name->name);
        if (result != ISC_R_SUCCESS)
            goto out;
    }

    /*
     * Now, while keeping the name locked, search for the address.
     * Three possibilities:  One, the address doesn't exist.
     * Two, the address exists, but we aren't linked to it.
     * Three, the address exists and we are linked to it.
     * (1) causes a new entry and namehook to be created.
     * (2) causes only a new namehook.
     * (3) is an error.
     */
    addr_bucket = DNS_ADB_INVALIDBUCKET;
    entry = find_entry_and_lock(adb, addr, &addr_bucket);
    /*
     * Case (1):  new entry and namehook.
     */
    if (entry == NULL) {
        entry = new_adbentry(adb);
        if (entry == NULL) {
            result = ISC_R_NOMEMORY;
            goto out;
        }
        free_entry = ISC_TRUE;
    }

    /*
     * Case (3):  entry exists, we're linked.
     */
    namehook = ISC_LIST_HEAD(name->namehooks);
    while (namehook != NULL) {
        if (namehook->entry == entry) {
            result = ISC_R_EXISTS;
            goto out;
        }
        namehook = ISC_LIST_NEXT(namehook, link);
    }

    /*
     * Case (2):  New namehook, link to entry from above.
     */
    namehook = new_adbnamehook(adb, entry);
    if (namehook == NULL) {
        result = ISC_R_NOMEMORY;
        goto out;
    }
    free_namehook = ISC_TRUE;
    ISC_LIST_APPEND(name->namehooks, namehook, link);

    entry->lock_bucket = addr_bucket;
    inc_entry_refcnt(adb, entry, ISC_FALSE);
    entry->sockaddr = *addr;

    /*
     * If needed, string up the name and entry.  Do the name last, since
     * adding multiple addresses is simplified in that case.
     */
    if (!ISC_LINK_LINKED(name, link))
        ISC_LIST_PREPEND(adb->names[name_bucket], name, link);
    if (!ISC_LINK_LINKED(entry, link))
        ISC_LIST_PREPEND(adb->entries[addr_bucket], entry, link);
    UNLOCK(&adb->namelocks[name_bucket]);
    name_bucket = DNS_ADB_INVALIDBUCKET;
    UNLOCK(&adb->entrylocks[addr_bucket]);
    addr_bucket = DNS_ADB_INVALIDBUCKET;

    return (ISC_R_SUCCESS);

 out:
    if (free_name)
        free_adbname(adb, &name);
    if (free_entry)
        isc_mempool_put(adb->emp, entry);
    if (free_namehook)
        isc_mempool_put(adb->nhmp, namehook);
    if (name_bucket != DNS_ADB_INVALIDBUCKET)
        UNLOCK(&adb->namelocks[name_bucket]);
    if (addr_bucket != DNS_ADB_INVALIDBUCKET)
        UNLOCK(&adb->entrylocks[addr_bucket]);

    return (result);
}

void
dns_adb_done(dns_adb_t *adb, dns_adbhandle_t **handlep)
{
    dns_adbhandle_t *handle;
    dns_adbentry_t *entry;
    dns_adbaddrinfo_t *ai;
    int bucket;

    REQUIRE(DNS_ADB_VALID(adb));

    REQUIRE(handlep != NULL && DNS_ADBHANDLE_VALID(*handlep));
    handle = *handlep;
    *handlep = NULL;

    REQUIRE(!ISC_LINK_LINKED(handle, next));

    LOCK(&handle->lock);
    bucket = handle->name_bucket;
    if (bucket == DNS_ADB_INVALIDBUCKET)
        goto cleanup;
    /*
     * Try to lock the name bucket.  If this fails, unlock the handle,
     * lock the name bucket, and then lock the handle again.
     */
    if (isc_mutex_trylock(&adb->namelocks[bucket]) != ISC_R_SUCCESS) {
        UNLOCK(&handle->lock);
        LOCK(&adb->namelocks[bucket]);
        LOCK(&handle->lock);
    }
    bucket = handle->name_bucket;
    if (bucket != DNS_ADB_INVALIDBUCKET) {
        ISC_LIST_UNLINK(handle->adbname->handles, handle, link);
        handle->adbname = NULL;
        handle->name_bucket = DNS_ADB_INVALIDBUCKET;
    }
    UNLOCK(&adb->namelocks[bucket]);
    bucket = DNS_ADB_INVALIDBUCKET;

 cleanup:
    UNLOCK(&handle->lock);

    /*
     * The handle doesn't exist on any list, and nothing is locked.
     * Return the handle to the memory pool, and decrement the adb's
     * reference count.
     */
    ai = ISC_LIST_HEAD(handle->list);
    while (ai != NULL) {
        ISC_LIST_UNLINK(handle->list, ai, link);
        entry = ai->entry;
        ai->entry = NULL;
        ai->sockaddr = NULL;
        INSIST(DNS_ADBENTRY_VALID(entry));
        dec_entry_refcnt(adb, entry, ISC_TRUE);
        free_adbaddrinfo(adb, &ai);
        ai = ISC_LIST_HEAD(handle->list);
    }
    free_adbhandle(adb, &handle);
}

void
dns_adb_dump(dns_adb_t *adb, FILE *f)
{
    int i;
    isc_sockaddr_t *sa;
    dns_adbname_t *name;
    dns_adbentry_t *entry;
    char tmp[512];
    const char *tmpp;

    REQUIRE(DNS_ADB_VALID(adb));
    REQUIRE(f != NULL);

    /*
     * Lock the adb itself, lock all the name buckets, then lock all
     * the entry buckets.  This should put the adb into a state where
     * nothing can change, so we can iterate through everything and
     * print at our leasure.
     */

    LOCK(&adb->lock);

    for (i = 0 ; i < DNS_ADBNAMELIST_LENGTH ; i++)
        LOCK(&adb->namelocks[i]);
    for (i = 0 ; i < DNS_ADBENTRYLIST_LENGTH ; i++)
        LOCK(&adb->entrylocks[i]);

    /*
     * Dump the names
     */
    fprintf(f, "Names:\n");
    for (i = 0 ; i < DNS_ADBNAMELIST_LENGTH ; i++) {
        name = ISC_LIST_HEAD(adb->names[i]);
        if (name == NULL)
            continue;
        fprintf(f, "Name bucket %d:\n", i);
        while (name != NULL) {
            fprintf(f, "name %p\n", name);
            if (!DNS_ADBNAME_VALID(name))
                fprintf(f, "\tMAGIC %08x\n", name->magic);
            fprintf(f, "\t");
            print_dns_name(f, &name->name);
            fprintf(f, "\n");
            print_namehook_list(f, name);
            fprintf(f, "\n");
            print_handle_list(f, name);
            fprintf(f, "\n");

            name = ISC_LIST_NEXT(name, link);
        }
    }

    /*
     * Dump the entries
     */
    fprintf(f, "Entries:\n");
    for (i = 0 ; i < DNS_ADBENTRYLIST_LENGTH ; i++) {
        entry = ISC_LIST_HEAD(adb->entries[i]);
        if (entry == NULL)
            continue;
        fprintf(f, "Entry bucket %d:\n", i);
        while (entry != NULL) {
            if (!DNS_ADBENTRY_VALID(entry))
                fprintf(f, "\tMAGIC %08x\n", entry->magic);
            if (entry->lock_bucket != i)
                fprintf(f, "\tWRONG BUCKET!  lock_bucket %d\n",
                    entry->lock_bucket);

            sa = &entry->sockaddr;
            switch (sa->type.sa.sa_family) {
            case AF_INET:
                tmpp = inet_ntop(AF_INET,
                         &sa->type.sin.sin_addr,
                         tmp, sizeof tmp);
                break;
            case AF_INET6:
                tmpp = inet_ntop(AF_INET6,
                         &sa->type.sin6.sin6_addr,
                         tmp, sizeof tmp);
                break;
            default:
                tmpp = "UnkFamily";
            }

            if (tmpp == NULL)
                tmpp = "CANNOT TRANSLATE ADDRESS!";

            fprintf(f, "\trefcnt %u flags %08x goodness %d"
                " srtt %u addr %s\n",
                entry->refcnt, entry->flags, entry->goodness,
                entry->srtt, tmpp);

            entry = ISC_LIST_NEXT(entry, link);
        }
    }

    /*
     * Unlock everything
     */
    for (i = 0 ; i < DNS_ADBENTRYLIST_LENGTH ; i++)
        UNLOCK(&adb->entrylocks[i]);
    for (i = 0 ; i < DNS_ADBNAMELIST_LENGTH ; i++)
        UNLOCK(&adb->namelocks[i]);
    UNLOCK(&adb->lock);
}

void
dns_adb_dumphandle(dns_adb_t *adb, dns_adbhandle_t *handle, FILE *f)
{
    char tmp[512];
    const char *tmpp;
    dns_adbaddrinfo_t *ai;
    isc_sockaddr_t *sa;

    /*
     * Not used currently, in the API Just In Case we
     * want to dump out the name and/or entries too.
     */
    (void)adb;

    LOCK(&handle->lock);

    fprintf(f, "Handle %p\n", handle);
    fprintf(f, "\tquery_pending %d, result %d (%s)\n",
        handle->query_pending, handle->result,
        isc_result_totext(handle->result));
    fprintf(f, "\tname_bucket %d, name %p, event sender %p\n",
        handle->name_bucket, handle->adbname, handle->event.sender);

    ai = ISC_LIST_HEAD(handle->list);
    if (ai != NULL)
        fprintf(f, "\tAddresses:\n");
    while (ai != NULL) {
        sa = ai->sockaddr;
        switch (sa->type.sa.sa_family) {
        case AF_INET:
            tmpp = inet_ntop(AF_INET, &sa->type.sin.sin_addr,
                     tmp, sizeof tmp);
            break;
        case AF_INET6:
            tmpp = inet_ntop(AF_INET6, &sa->type.sin6.sin6_addr,
                     tmp, sizeof tmp);
            break;
        default:
            tmpp = "UnkFamily";
        }

        if (tmpp == NULL)
            tmpp = "CANNOT TRANSLATE ADDRESS!";

        fprintf(f, "\t\tentry %p, flags %08x goodness %d"
            " srtt %u addr %s\n",
            ai->entry, ai->flags, ai->goodness, ai->srtt, tmpp);

        ai = ISC_LIST_NEXT(ai, link);
    }

    UNLOCK(&handle->lock);
}

static void
print_dns_name(FILE *f, dns_name_t *name)
{
    char buf[257];
    isc_buffer_t b;

    INSIST(f != NULL);

    memset(buf, 0, sizeof (buf));
    isc_buffer_init(&b, buf, sizeof (buf) - 1, ISC_BUFFERTYPE_TEXT);

    dns_name_totext(name, ISC_FALSE, &b);
    fprintf(f, buf); /* safe, since names < 256 chars, and we memset */
}

static void
print_namehook_list(FILE *f, dns_adbname_t *n)
{
    dns_adbnamehook_t *nh;

    nh = ISC_LIST_HEAD(n->namehooks);
    if (nh == NULL)
        fprintf(f, "\t\tNo name hooks\n");

    while (nh != NULL) {
        fprintf(f, "\t\tHook %p -> entry %p\n", nh, nh->entry);
        nh = ISC_LIST_NEXT(nh, link);
    }
}

static void
print_handle_list(FILE *f, dns_adbname_t *name)
{
    dns_adbhandle_t *handle;

    handle = ISC_LIST_HEAD(name->handles);
    if (handle == NULL)
        fprintf(f, "\t\tNo handles\n");

    while (handle != NULL) {
        fprintf(f, "\t\tHandle %p\n", handle);
        handle = ISC_LIST_NEXT(handle, link);
    }
}