lib/dns/byaddr.c

	byaddr.c revision 6028d1ce0380d0ba7f6c6ecd1ad20b31ddd1becb
/*
 * 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.
 */

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

/*
 * XXXRTH  We could use a static event...
 */

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

#define BYADDR_MAGIC            0x42794164U /* ByAd. */
#define VALID_BYADDR(b)         ((b) != NULL && \
                     (b)->magic == BYADDR_MAGIC)

#define MAX_RESTARTS 16

static void byaddr_find(dns_byaddr_t *byaddr, dns_fetchevent_t *event);

static char hex_digits[] = {
    '0', '1', '2', '3', '4', '5', '6', '7',
    '8', '9', 'a', 'b', 'c', 'd', 'e', 'f'
};

static inline isc_result_t
address_to_ptr_name(dns_byaddr_t *byaddr, isc_netaddr_t *address) {
    char textname[128];
    unsigned char *bytes;
    int i;
    char *cp;
    isc_buffer_t buffer;
    unsigned int len;

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

    /*
     * We create the text representation and then convert to a
     * dns_name_t.  This is not maximally efficient, but it keeps all
     * of the knowledge of wire format in the dns_name_ routines.
     */

    dns_fixedname_init(&byaddr->name);
    bytes = (unsigned char *)(&address->type);
    if (address->family == AF_INET) {
        (void)sprintf(textname, "%u.%u.%u.%u.in-addr.arpa.",
                  (bytes[3] & 0xff),
                  (bytes[2] & 0xff),
                  (bytes[1] & 0xff),
                  (bytes[0] & 0xff));
    } else if (address->family == AF_INET6) {
        if ((byaddr->options & DNS_BYADDROPT_IPV6NIBBLE) != 0) {
            cp = textname;
            for (i = 15; i >= 0; i--) {
                *cp++ = hex_digits[bytes[i] & 0x0f];
                *cp++ = '.';
                *cp++ = hex_digits[(bytes[i] >> 4) & 0x0f];
                *cp++ = '.';
            }
            strcpy(cp, "ip6.int.");
        } else {
            cp = textname;
            *cp++ = '\\';
            *cp++ = '[';
            *cp++ = 'x';
            for (i = 0; i < 16; i += 2) {
                *cp++ = hex_digits[(bytes[i] >> 4) & 0x0f];
                *cp++ = hex_digits[bytes[i] & 0x0f];
                *cp++ = hex_digits[(bytes[i+1] >> 4) & 0x0f];
                *cp++ = hex_digits[bytes[i+1] & 0x0f];
            }
            strcpy(cp, "].ip6.int.");
        }
    } else
        return (ISC_R_NOTIMPLEMENTED);

    len = (unsigned int)strlen(textname);
    isc_buffer_init(&buffer, textname, len);
    isc_buffer_add(&buffer, len);
    return (dns_name_fromtext(dns_fixedname_name(&byaddr->name),
                  &buffer, dns_rootname, ISC_FALSE, NULL));
}

static inline isc_result_t
copy_ptr_targets(dns_byaddr_t *byaddr) {
    isc_result_t result;
    dns_name_t *name;
    dns_name_t target;
    dns_rdata_t rdata;
    isc_region_t r;

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

    result = dns_rdataset_first(&byaddr->rdataset);
    while (result == ISC_R_SUCCESS) {
        dns_rdataset_current(&byaddr->rdataset, &rdata);
        r.base = rdata.data;
        r.length = rdata.length;
        dns_name_init(&target, NULL);
        dns_name_fromregion(&target, &r);
        name = isc_mem_get(byaddr->mctx, sizeof *name);
        if (name == NULL)
            return (ISC_R_NOMEMORY);
        dns_name_init(name, NULL);
        result = dns_name_dup(&target, byaddr->mctx, name);
        if (result != ISC_R_SUCCESS) {
            isc_mem_put(byaddr->mctx, name, sizeof *name);
            return (ISC_R_NOMEMORY);
        }
        ISC_LIST_APPEND(byaddr->event->names, name, link);
        result = dns_rdataset_next(&byaddr->rdataset);
    }
    if (result == ISC_R_NOMORE)
        result = ISC_R_SUCCESS;

    return (result);
}

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

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

    byaddr_find(byaddr, fevent);
}

static inline isc_result_t
start_fetch(dns_byaddr_t *byaddr) {
    isc_result_t result;

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

    REQUIRE(byaddr->fetch == NULL);

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

    return (result);
}

static void
byaddr_find(dns_byaddr_t *byaddr, dns_fetchevent_t *event) {
    isc_result_t result;
    isc_boolean_t want_restart;
    isc_boolean_t send_event = ISC_FALSE;
    isc_event_t *ievent;
    dns_name_t *name, *fname, *prefix;
    dns_name_t tname;
    dns_fixedname_t foundname, fixed;
    dns_rdata_t rdata;
    isc_region_t r;
    unsigned int nlabels, nbits;
    int order;
    dns_namereln_t namereln;

    REQUIRE(VALID_BYADDR(byaddr));

    LOCK(&byaddr->lock);

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

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

        if (event == NULL && !byaddr->canceled) {
            dns_fixedname_init(&foundname);
            fname = dns_fixedname_name(&foundname);
            INSIST(!dns_rdataset_isassociated(&byaddr->rdataset));
            result = dns_view_find(byaddr->view, name,
                           dns_rdatatype_ptr, 0, 0,
                           ISC_FALSE, fname,
                           &byaddr->rdataset, NULL);
            if (result == ISC_R_NOTFOUND) {
                /*
                 * We don't know anything about the name.
                 * Launch a fetch.
                 */
                result = start_fetch(byaddr);
                if (result != ISC_R_SUCCESS)
                    send_event = ISC_TRUE;
                goto done;
            }
        } else {
            result = event->result;
            fname = dns_fixedname_name(&event->foundname);
            dns_resolver_destroyfetch(&byaddr->fetch);
            INSIST(event->rdataset == &byaddr->rdataset);
            INSIST(event->sigrdataset == NULL);
            /*
             * Detach (if necessary) from things we know we
             * don't care about.
             */
            if (event->node != NULL)
                dns_db_detachnode(event->db, &event->node);
            if (event->db != NULL)
                dns_db_detach(&event->db);
        }

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

        switch (result) {
        case ISC_R_SUCCESS:
            result = copy_ptr_targets(byaddr);
            send_event = ISC_TRUE;
            break;
        case DNS_R_CNAME:
            /*
             * Copy the CNAME's target into the byaddr's
             * query name and start over.
             */
            result = dns_rdataset_first(&byaddr->rdataset);
            if (result != ISC_R_SUCCESS)
                break;
            dns_rdataset_current(&byaddr->rdataset, &rdata);
            r.base = rdata.data;
            r.length = rdata.length;
            dns_name_init(&tname, NULL);
            dns_name_fromregion(&tname, &r);
            result = dns_name_concatenate(&tname, NULL, name,
                              NULL);
            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(&byaddr->rdataset);
            if (result != ISC_R_SUCCESS)
                break;
            dns_rdataset_current(&byaddr->rdataset, &rdata);
            r.base = rdata.data;
            r.length = rdata.length;
            dns_name_init(&tname, NULL);
            dns_name_fromregion(&tname, &r);
            /*
             * 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)
                break;
            result = dns_name_concatenate(prefix, &tname, name,
                              NULL);
            if (result == ISC_R_SUCCESS)
                want_restart = ISC_TRUE;
            break;
        default:
            send_event = ISC_TRUE;
        }

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

        if (event != NULL) {
            ievent = (isc_event_t *)event;
            isc_event_free(&ievent);
            event = NULL;
        }

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

    } while (want_restart);

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

    UNLOCK(&byaddr->lock);
}

static void
bevent_destroy(isc_event_t *event) {
    dns_byaddrevent_t *bevent;
    dns_name_t *name, *next_name;
    isc_mem_t *mctx;

    REQUIRE(event->ev_type == DNS_EVENT_BYADDRDONE);
    mctx = event->ev_destroy_arg;
    bevent = (dns_byaddrevent_t *)event;

    for (name = ISC_LIST_HEAD(bevent->names);
         name != NULL;
         name = next_name) {
        next_name = ISC_LIST_NEXT(name, link);
        dns_name_free(name, mctx);
        isc_mem_put(mctx, name, sizeof *name);
    }
    isc_mem_put(mctx, event, event->ev_size);
}

isc_result_t
dns_byaddr_create(isc_mem_t *mctx, isc_netaddr_t *address, dns_view_t *view,
          unsigned int options, isc_task_t *task,
          isc_taskaction_t action, void *arg, dns_byaddr_t **byaddrp)
{
    isc_result_t result;
    dns_byaddr_t *byaddr;
    isc_event_t *ievent;

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

    byaddr->event = isc_mem_get(mctx, sizeof *byaddr->event);
    if (byaddr->event == NULL) {
        result = ISC_R_NOMEMORY;
        goto cleanup_byaddr;
    }
    ISC_EVENT_INIT(byaddr->event, sizeof *byaddr->event, 0, NULL,
               DNS_EVENT_BYADDRDONE, action, arg, byaddr,
               bevent_destroy, mctx);
    byaddr->event->result = ISC_R_FAILURE;
    ISC_LIST_INIT(byaddr->event->names);

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

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

    result = address_to_ptr_name(byaddr, address);
    if (result != ISC_R_SUCCESS)
        goto cleanup_lock;

    byaddr->view = NULL;
    dns_view_attach(view, &byaddr->view);
    byaddr->fetch = NULL;
    byaddr->restarts = 0;
    byaddr->canceled = ISC_FALSE;
    dns_rdataset_init(&byaddr->rdataset);
    byaddr->magic = BYADDR_MAGIC;

    *byaddrp = byaddr;

    byaddr_find(byaddr, NULL);

    return (ISC_R_SUCCESS);

 cleanup_lock:
    isc_mutex_destroy(&byaddr->lock);

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

    isc_task_detach(&byaddr->task);

 cleanup_byaddr:
    isc_mem_put(mctx, byaddr, sizeof *byaddr);

    return (result);
}

void
dns_byaddr_cancel(dns_byaddr_t *byaddr) {
    REQUIRE(VALID_BYADDR(byaddr));

    LOCK(&byaddr->lock);

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

    UNLOCK(&byaddr->lock);
}

void
dns_byaddr_destroy(dns_byaddr_t **byaddrp) {
    dns_byaddr_t *byaddr;

    REQUIRE(byaddrp != NULL);
    byaddr = *byaddrp;
    REQUIRE(VALID_BYADDR(byaddr));
    REQUIRE(byaddr->event == NULL);
    REQUIRE(byaddr->task == NULL);
    REQUIRE(byaddr->view == NULL);

    isc_mutex_destroy(&byaddr->lock);
    byaddr->magic = 0;
    isc_mem_put(byaddr->mctx, byaddr, sizeof *byaddr);

    *byaddrp = NULL;
}