lib/dns/lookup.c

	lookup.c revision 13090db2b1c210b8386793ff0cbbb0b4348c1eca
/*
 * Copyright (C) 2000  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: lookup.c,v 1.6 2000/12/20 03:38:42 bwelling Exp $ */

#include <config.h>

#include <isc/mem.h>
#include <isc/netaddr.h>
#include <isc/string.h>     /* Required for HP/UX (and others?) */
#include <isc/task.h>
#include <isc/util.h>

#include <dns/db.h>
#include <dns/events.h>
#include <dns/lookup.h>
#include <dns/rdata.h>
#include <dns/rdataset.h>
#include <dns/rdatastruct.h>
#include <dns/resolver.h>
#include <dns/result.h>
#include <dns/view.h>

struct dns_lookup {
    /* Unlocked. */
    unsigned int        magic;
    isc_mem_t *     mctx;
    isc_mutex_t     lock;
    dns_rdatatype_t     type;
    dns_fixedname_t     name;
    /* Locked by lock. */
    unsigned int        options;
    isc_task_t *        task;
    dns_view_t *        view;
    dns_lookupevent_t * event;
    dns_fetch_t *       fetch;
    unsigned int        restarts;
    isc_boolean_t       canceled;
    dns_rdataset_t      rdataset;
    dns_rdataset_t      sigrdataset;
};

#define LOOKUP_MAGIC            ISC_MAGIC('l', 'o', 'o', 'k')
#define VALID_LOOKUP(l)         ISC_MAGIC_VALID((l), LOOKUP_MAGIC)

#define MAX_RESTARTS 16

static void lookup_find(dns_lookup_t *lookup, dns_fetchevent_t *event);

static void
fetch_done(isc_task_t *task, isc_event_t *event) {
    dns_lookup_t *lookup = event->ev_arg;
    dns_fetchevent_t *fevent;

    UNUSED(task);
    REQUIRE(event->ev_type == DNS_EVENT_FETCHDONE);
    REQUIRE(VALID_LOOKUP(lookup));
    REQUIRE(lookup->task == task);
    fevent = (dns_fetchevent_t *)event;
    REQUIRE(fevent->fetch == lookup->fetch);

    lookup_find(lookup, fevent);
}

static inline isc_result_t
start_fetch(dns_lookup_t *lookup) {
    isc_result_t result;

    /*
     * The caller must be holding the lookup's lock.
     */

    REQUIRE(lookup->fetch == NULL);

    result = dns_resolver_createfetch(lookup->view->resolver,
                      dns_fixedname_name(&lookup->name),
                      lookup->type,
                      NULL, NULL, NULL, 0,
                      lookup->task, fetch_done, lookup,
                      &lookup->rdataset,
                      &lookup->sigrdataset,
                      &lookup->fetch);

    return (result);
}

static isc_result_t
build_event(dns_lookup_t *lookup) {
    dns_name_t *name = NULL;
    dns_rdataset_t *rdataset = NULL;
    dns_rdataset_t *sigrdataset = NULL;
    isc_result_t result;

    name = isc_mem_get(lookup->mctx, sizeof(dns_name_t));
    if (name == NULL) {
        result = ISC_R_NOMEMORY;
        goto fail;
    }
    dns_name_init(name, NULL);
    result = dns_name_dup(dns_fixedname_name(&lookup->name),
                  lookup->mctx, name);
    if (result != ISC_R_SUCCESS)
        goto fail;

    if (dns_rdataset_isassociated(&lookup->rdataset)) {
        rdataset = isc_mem_get(lookup->mctx, sizeof(dns_rdataset_t));
        if (rdataset == NULL) {
            result = ISC_R_NOMEMORY;
            goto fail;
        }
        dns_rdataset_init(rdataset);
        dns_rdataset_clone(&lookup->rdataset, rdataset);
    }

    if (dns_rdataset_isassociated(&lookup->sigrdataset)) {
        sigrdataset = isc_mem_get(lookup->mctx,
                      sizeof(dns_rdataset_t));
        if (sigrdataset == NULL) {
            result = ISC_R_NOMEMORY;
            goto fail;
        }
        dns_rdataset_init(sigrdataset);
        dns_rdataset_clone(&lookup->sigrdataset, sigrdataset);
    }

    lookup->event->name = name;
    lookup->event->rdataset = rdataset;
    lookup->event->sigrdataset = sigrdataset;

    return (ISC_R_SUCCESS);

 fail:
    if (name != NULL) {
        if (dns_name_dynamic(name))
            dns_name_free(name, lookup->mctx);
        isc_mem_put(lookup->mctx, name, sizeof(dns_name_t));
    }
    if (rdataset != NULL) {
        if (dns_rdataset_isassociated(rdataset))
            dns_rdataset_disassociate(rdataset);
        isc_mem_put(lookup->mctx, rdataset, sizeof(dns_rdataset_t));
    }
    if (sigrdataset != NULL) {
        if (dns_rdataset_isassociated(sigrdataset))
            dns_rdataset_disassociate(sigrdataset);
        isc_mem_put(lookup->mctx, sigrdataset, sizeof(dns_rdataset_t));
    }
    return (result);
}

static isc_result_t
view_find(dns_lookup_t *lookup, dns_name_t *foundname) {
    isc_result_t result;
    dns_name_t *name = dns_fixedname_name(&lookup->name);
    dns_rdatatype_t type;

    if (lookup->type == dns_rdatatype_sig)
        type = dns_rdatatype_any;
    else
        type = lookup->type;

    result = dns_view_find(lookup->view, name, type, 0, 0, ISC_FALSE,
                   &lookup->event->db, &lookup->event->node,
                   foundname, &lookup->rdataset,
                   &lookup->sigrdataset);
    return (result);
}

static void
lookup_find(dns_lookup_t *lookup, dns_fetchevent_t *event) {
    isc_result_t result;
    isc_boolean_t want_restart;
    isc_boolean_t send_event = ISC_FALSE;
    dns_name_t *name, *fname, *prefix;
    dns_fixedname_t foundname, fixed;
    dns_rdata_t rdata = DNS_RDATA_INIT;
    unsigned int nlabels, nbits;
    int order;
    dns_namereln_t namereln;
    dns_rdata_cname_t cname;
    dns_rdata_dname_t dname;

    REQUIRE(VALID_LOOKUP(lookup));

    LOCK(&lookup->lock);

    result = ISC_R_SUCCESS;
    name = dns_fixedname_name(&lookup->name);

    do {
        lookup->restarts++;
        want_restart = ISC_FALSE;

        if (event == NULL && !lookup->canceled) {
            dns_fixedname_init(&foundname);
            fname = dns_fixedname_name(&foundname);
            INSIST(!dns_rdataset_isassociated(&lookup->rdataset));
            INSIST(!dns_rdataset_isassociated
                        (&lookup->sigrdataset));
            result = view_find(lookup, fname);
            if (result == ISC_R_NOTFOUND) {
                /*
                 * We don't know anything about the name.
                 * Launch a fetch.
                 */
                if  (lookup->event->node != NULL) {
                    INSIST(lookup->event->db != NULL);
                    dns_db_detachnode(lookup->event->db,
                             &lookup->event->node);
                }
                if (lookup->event->db != NULL)
                    dns_db_detach(&lookup->event->db);
                result = start_fetch(lookup);
                if (result != ISC_R_SUCCESS)
                    send_event = ISC_TRUE;
                goto done;
            }
        } else {
            result = event->result;
            fname = dns_fixedname_name(&event->foundname);
            dns_resolver_destroyfetch(&lookup->fetch);
            INSIST(event->rdataset == &lookup->rdataset);
            INSIST(event->sigrdataset == &lookup->sigrdataset);
        }

        /*
         * If we've been canceled, forget about the result.
         */
        if (lookup->canceled)
            result = ISC_R_CANCELED;

        switch (result) {
        case ISC_R_SUCCESS:
            result = build_event(lookup);
            send_event = ISC_TRUE;
            if (event == NULL)
                break;
            if (event->db != NULL)
                dns_db_attach(event->db, &lookup->event->db);
            if (event->node != NULL)
                dns_db_attachnode(lookup->event->db,
                          event->node,
                          &lookup->event->node);
            break;
        case DNS_R_CNAME:
            /*
             * Copy the CNAME's target into the lookup's
             * query name and start over.
             */
            result = dns_rdataset_first(&lookup->rdataset);
            if (result != ISC_R_SUCCESS)
                break;
            dns_rdataset_current(&lookup->rdataset, &rdata);
            result = dns_rdata_tostruct(&rdata, &cname, NULL);
            dns_rdata_reset(&rdata);
            if (result != ISC_R_SUCCESS)
                break;
            result = dns_name_concatenate(&cname.cname, NULL, name,
                              NULL);
            dns_rdata_freestruct(&cname);
            if (result == ISC_R_SUCCESS)
                want_restart = ISC_TRUE;
            break;
        case DNS_R_DNAME:
            namereln = dns_name_fullcompare(name, fname, &order,
                            &nlabels, &nbits);
            INSIST(namereln == dns_namereln_subdomain);
            /*
             * Get the target name of the DNAME.
             */
            result = dns_rdataset_first(&lookup->rdataset);
            if (result != ISC_R_SUCCESS)
                break;
            dns_rdataset_current(&lookup->rdataset, &rdata);
            result = dns_rdata_tostruct(&rdata, &dname, NULL);
            dns_rdata_reset(&rdata);
            if (result != ISC_R_SUCCESS)
                break;
            /*
             * Construct the new query name and start over.
             */
            dns_fixedname_init(&fixed);
            prefix = dns_fixedname_name(&fixed);
            result = dns_name_split(name, nlabels, nbits, prefix,
                        NULL);
            if (result != ISC_R_SUCCESS) {
                dns_rdata_freestruct(&dname);
                break;
            }
            result = dns_name_concatenate(prefix, &dname.dname,
                              name, NULL);
            dns_rdata_freestruct(&dname);
            if (result == ISC_R_SUCCESS)
                want_restart = ISC_TRUE;
            break;
        default:
            send_event = ISC_TRUE;
        }

    done:
        if (dns_rdataset_isassociated(&lookup->rdataset))
            dns_rdataset_disassociate(&lookup->rdataset);
        if (dns_rdataset_isassociated(&lookup->sigrdataset))
            dns_rdataset_disassociate(&lookup->sigrdataset);

        if (event != NULL) {
            if (event->node != NULL)
                dns_db_detachnode(event->db, &event->node);
            if (event->db != NULL)
                dns_db_detach(&event->db);
            isc_event_free((isc_event_t **)&event);
        }

        /*
         * Limit the number of restarts.
         */
        if (want_restart && lookup->restarts == MAX_RESTARTS) {
            want_restart = ISC_FALSE;
            result = ISC_R_QUOTA;
            send_event = ISC_TRUE;
        }

    } while (want_restart);

    if (send_event) {
        lookup->event->result = result;
        lookup->event->ev_sender = lookup;
        isc_task_sendanddetach(&lookup->task,
                       (isc_event_t **)&lookup->event);
        dns_view_detach(&lookup->view);
    }

    UNLOCK(&lookup->lock);
}

static void
levent_destroy(isc_event_t *event) {
    dns_lookupevent_t *levent;
    isc_mem_t *mctx;

    REQUIRE(event->ev_type == DNS_EVENT_LOOKUPDONE);
    mctx = event->ev_destroy_arg;
    levent = (dns_lookupevent_t *)event;

    if (levent->name != NULL) {
        if (dns_name_dynamic(levent->name))
            dns_name_free(levent->name, mctx);
        isc_mem_put(mctx, levent->name, sizeof(dns_name_t));
    }
    if (levent->rdataset != NULL) {
        dns_rdataset_disassociate(levent->rdataset);
        isc_mem_put(mctx, levent->rdataset, sizeof(dns_rdataset_t));
    }
    if (levent->sigrdataset != NULL) {
        dns_rdataset_disassociate(levent->sigrdataset);
        isc_mem_put(mctx, levent->sigrdataset, sizeof(dns_rdataset_t));
    }
    if (levent->node != NULL)
        dns_db_detachnode(levent->db, &levent->node);
    if (levent->db != NULL)
        dns_db_detach(&levent->db);
    isc_mem_put(mctx, event, event->ev_size);
}


isc_result_t
dns_lookup_create(isc_mem_t *mctx, dns_name_t *name, dns_rdatatype_t type,
          dns_view_t *view, unsigned int options, isc_task_t *task,
          isc_taskaction_t action, void *arg, dns_lookup_t **lookupp)
{
    isc_result_t result;
    dns_lookup_t *lookup;
    isc_event_t *ievent;

    lookup = isc_mem_get(mctx, sizeof *lookup);
    if (lookup == NULL)
        return (ISC_R_NOMEMORY);
    lookup->mctx = mctx;
    lookup->options = options;

    ievent = isc_event_allocate(mctx, lookup, DNS_EVENT_LOOKUPDONE,
                    action, arg, sizeof *lookup->event);
    if (ievent == NULL) {
        result = ISC_R_NOMEMORY;
        goto cleanup_lookup;
    }
    lookup->event = (dns_lookupevent_t *)ievent;
    lookup->event->ev_destroy = levent_destroy;
    lookup->event->ev_destroy_arg = mctx;
    lookup->event->result = ISC_R_FAILURE;
    lookup->event->name = NULL;
    lookup->event->rdataset = NULL;
    lookup->event->sigrdataset = NULL;
    lookup->event->db = NULL;
    lookup->event->node = NULL;

    lookup->task = NULL;
    isc_task_attach(task, &lookup->task);

    result = isc_mutex_init(&lookup->lock);
    if (result != ISC_R_SUCCESS)
        goto cleanup_event;

    dns_fixedname_init(&lookup->name);

    result = dns_name_concatenate(name, NULL,
                      dns_fixedname_name(&lookup->name), NULL);
    if (result != ISC_R_SUCCESS)
        goto cleanup_lock;

    lookup->type = type;
    lookup->view = NULL;
    dns_view_attach(view, &lookup->view);
    lookup->fetch = NULL;
    lookup->restarts = 0;
    lookup->canceled = ISC_FALSE;
    dns_rdataset_init(&lookup->rdataset);
    dns_rdataset_init(&lookup->sigrdataset);
    lookup->magic = LOOKUP_MAGIC;

    *lookupp = lookup;

    lookup_find(lookup, NULL);

    return (ISC_R_SUCCESS);

 cleanup_lock:
    DESTROYLOCK(&lookup->lock);

 cleanup_event:
    ievent = (isc_event_t *)lookup->event;
    isc_event_free(&ievent);
    lookup->event = NULL;

    isc_task_detach(&lookup->task);

 cleanup_lookup:
    isc_mem_put(mctx, lookup, sizeof *lookup);

    return (result);
}

void
dns_lookup_cancel(dns_lookup_t *lookup) {
    REQUIRE(VALID_LOOKUP(lookup));

    LOCK(&lookup->lock);

    if (!lookup->canceled) {
        lookup->canceled = ISC_TRUE;
        if (lookup->fetch != NULL) {
            INSIST(lookup->view != NULL);
            dns_resolver_cancelfetch(lookup->fetch);
        }
    }

    UNLOCK(&lookup->lock);
}

void
dns_lookup_destroy(dns_lookup_t **lookupp) {
    dns_lookup_t *lookup;

    REQUIRE(lookupp != NULL);
    lookup = *lookupp;
    REQUIRE(VALID_LOOKUP(lookup));
    REQUIRE(lookup->event == NULL);
    REQUIRE(lookup->task == NULL);
    REQUIRE(lookup->view == NULL);
    if (dns_rdataset_isassociated(&lookup->rdataset))
        dns_rdataset_disassociate(&lookup->rdataset);
    if (dns_rdataset_isassociated(&lookup->sigrdataset))
        dns_rdataset_disassociate(&lookup->sigrdataset);

    DESTROYLOCK(&lookup->lock);
    lookup->magic = 0;
    isc_mem_put(lookup->mctx, lookup, sizeof *lookup);

    *lookupp = NULL;
}