sortlist.c

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/*
 * Copyright (C) 2004-2007  Internet Systems Consortium, Inc. ("ISC")
 * Copyright (C) 2000, 2001  Internet Software Consortium.
 *
 * Permission to use, copy, modify, and/or 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: sortlist.c,v 1.17 2007/09/14 01:46:05 marka Exp $ */

/*! \file */

#include <config.h>

#include <isc/mem.h>
#include <isc/util.h>

#include <dns/acl.h>
#include <dns/result.h>

#include <named/globals.h>
#include <named/server.h>
#include <named/sortlist.h>

ns_sortlisttype_t
ns_sortlist_setup(dns_acl_t *acl, isc_netaddr_t *clientaddr,
                  const void **argp)
{
        unsigned int i;

        if (acl == NULL)
                goto dont_sort;

        for (i = 0; i < acl->length; i++) {
                /*
                 * 'e' refers to the current 'top level statement'
                 * in the sortlist (see ARM).
                 */
                dns_aclelement_t *e = &acl->elements[i];
                dns_aclelement_t *try_elt;
                dns_aclelement_t *order_elt = NULL;
                const dns_aclelement_t *matched_elt = NULL;

                if (e->type == dns_aclelementtype_nestedacl) {
                        dns_acl_t *inner = e->nestedacl;

                        if (inner->length == 0)
                                try_elt = e;
                        else if (inner->length > 2)
                                goto dont_sort;
                        else if (inner->elements[0].negative)
                                goto dont_sort;
                        else {
                                try_elt = &inner->elements[0];
                                if (inner->length == 2)
                                        order_elt = &inner->elements[1];
                        }
                } else {
                        /*
                         * BIND 8 allows bare elements at the top level
                         * as an undocumented feature.
                         */
                        try_elt = e;
                }

                if (dns_aclelement_match(clientaddr, NULL, try_elt,
                                         &ns_g_server->aclenv,
                                         &matched_elt)) {
                        if (order_elt != NULL) {
                                if (order_elt->type ==
                                    dns_aclelementtype_nestedacl) {
                                        *argp = order_elt->nestedacl;
                                        return (NS_SORTLISTTYPE_2ELEMENT);
                                } else if (order_elt->type ==
                                           dns_aclelementtype_localhost &&
                                           ns_g_server->aclenv.localhost != NULL) {
                                        *argp = ns_g_server->aclenv.localhost;
                                        return (NS_SORTLISTTYPE_2ELEMENT);
                                } else if (order_elt->type ==
                                           dns_aclelementtype_localnets &&
                                           ns_g_server->aclenv.localnets != NULL) {
                                        *argp = ns_g_server->aclenv.localnets;
                                        return (NS_SORTLISTTYPE_2ELEMENT);
                                } else {
                                        /*
                                         * BIND 8 allows a bare IP prefix as
                                         * the 2nd element of a 2-element
                                         * sortlist statement.
                                         */
                                        *argp = order_elt;
                                        return (NS_SORTLISTTYPE_1ELEMENT);
                                }
                        } else {
                                INSIST(matched_elt != NULL);
                                *argp = matched_elt;
                                return (NS_SORTLISTTYPE_1ELEMENT);
                        }
                }
        }

        /* No match; don't sort. */
 dont_sort:
        *argp = NULL;
        return (NS_SORTLISTTYPE_NONE);
}

int
ns_sortlist_addrorder2(const isc_netaddr_t *addr, const void *arg) {
        const dns_acl_t *sortacl = (const dns_acl_t *) arg;
        int match;

        (void)dns_acl_match(addr, NULL, sortacl,
                            &ns_g_server->aclenv,
                            &match, NULL);
        if (match > 0)
                return (match);
        else if (match < 0)
                return (INT_MAX - (-match));
        else
                return (INT_MAX / 2);
}

int
ns_sortlist_addrorder1(const isc_netaddr_t *addr, const void *arg) {
        const dns_aclelement_t *matchelt = (const dns_aclelement_t *) arg;
        if (dns_aclelement_match(addr, NULL, matchelt,
                                 &ns_g_server->aclenv,
                                 NULL)) {
                return (0);
        } else {
                return (INT_MAX);
        }
}

void
ns_sortlist_byaddrsetup(dns_acl_t *sortlist_acl, isc_netaddr_t *client_addr,
                       dns_addressorderfunc_t *orderp,
                       const void **argp)
{
        ns_sortlisttype_t sortlisttype;

        sortlisttype = ns_sortlist_setup(sortlist_acl, client_addr, argp);

        switch (sortlisttype) {
        case NS_SORTLISTTYPE_1ELEMENT:
                *orderp = ns_sortlist_addrorder1;
                break;
        case NS_SORTLISTTYPE_2ELEMENT:
                *orderp = ns_sortlist_addrorder2;
                break;
        case NS_SORTLISTTYPE_NONE:
                *orderp = NULL;
                break;
        default:
                UNEXPECTED_ERROR(__FILE__, __LINE__,
                                 "unexpected return from ns_sortlist_setup(): "
                                 "%d", sortlisttype);
                break;
        }
}

---