lib/dns/iptable.c

/*
 * Copyright (C) 2007-2009, 2012  Internet Systems Consortium, Inc. ("ISC")
 *
 * 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.
 */

/* $Id$ */

#include <config.h>

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

#include <dns/acl.h>

static void destroy_iptable(dns_iptable_t *dtab);

/*
 * Create a new IP table and the underlying radix structure
 */
isc_result_t
dns_iptable_create(isc_mem_t *mctx, dns_iptable_t **target) {
    isc_result_t result;
    dns_iptable_t *tab;

    tab = isc_mem_get(mctx, sizeof(*tab));
    if (tab == NULL)
        return (ISC_R_NOMEMORY);
    tab->mctx = mctx;
    isc_refcount_init(&tab->refcount, 1);
    tab->radix = NULL;
    tab->magic = DNS_IPTABLE_MAGIC;

    result = isc_radix_create(mctx, &tab->radix, RADIX_MAXBITS);
    if (result != ISC_R_SUCCESS)
        goto cleanup;

    *target = tab;
    return (ISC_R_SUCCESS);

 cleanup:
    dns_iptable_detach(&tab);
    return (result);
}

isc_boolean_t dns_iptable_neg = ISC_FALSE;
isc_boolean_t dns_iptable_pos = ISC_TRUE;

/*
 * Add an IP prefix to an existing IP table
 */
isc_result_t
dns_iptable_addprefix(dns_iptable_t *tab, isc_netaddr_t *addr,
              isc_uint16_t bitlen, isc_boolean_t pos)
{
    isc_result_t result;
    isc_prefix_t pfx;
    isc_radix_node_t *node = NULL;
    int family;

    INSIST(DNS_IPTABLE_VALID(tab));
    INSIST(tab->radix);

    NETADDR_TO_PREFIX_T(addr, pfx, bitlen);

    result = isc_radix_insert(tab->radix, &node, NULL, &pfx);
    if (result != ISC_R_SUCCESS) {
        isc_refcount_destroy(&pfx.refcount);
        return(result);
    }

    /* If a node already contains data, don't overwrite it */
    family = pfx.family;
    if (family == AF_UNSPEC) {
        /* "any" or "none" */
        INSIST(pfx.bitlen == 0);
        if (pos) {
            if (node->data[0] == NULL)
                node->data[0] = &dns_iptable_pos;
            if (node->data[1] == NULL)
                node->data[1] = &dns_iptable_pos;
        } else {
            if (node->data[0] == NULL)
                node->data[0] = &dns_iptable_neg;
            if (node->data[1] == NULL)
                node->data[1] = &dns_iptable_neg;
        }
    } else {
        /* any other prefix */
        if (node->data[ISC_IS6(family)] == NULL) {
            if (pos)
                node->data[ISC_IS6(family)] = &dns_iptable_pos;
            else
                node->data[ISC_IS6(family)] = &dns_iptable_neg;
        }
    }

    isc_refcount_destroy(&pfx.refcount);
    return (ISC_R_SUCCESS);
}

/*
 * Merge one IP table into another one.
 */
isc_result_t
dns_iptable_merge(dns_iptable_t *tab, dns_iptable_t *source, isc_boolean_t pos)
{
    isc_result_t result;
    isc_radix_node_t *node, *new_node;
    int max_node = 0;

    RADIX_WALK (source->radix->head, node) {
        new_node = NULL;
        result = isc_radix_insert (tab->radix, &new_node, node, NULL);

        if (result != ISC_R_SUCCESS)
            return(result);

        /*
         * If we're negating a nested ACL, then we should
         * reverse the sense of every node.  However, this
         * could lead to a negative node in a nested ACL
         * becoming a positive match in the parent, which
         * could be a security risk.  To prevent this, we
         * just leave the negative nodes negative.
         */
        if (!pos) {
            if (node->data[0] &&
                *(isc_boolean_t *) node->data[0] == ISC_TRUE)
                new_node->data[0] = &dns_iptable_neg;

            if (node->data[1] &&
                *(isc_boolean_t *) node->data[1] == ISC_TRUE)
                new_node->data[1] = &dns_iptable_neg;
        }

        if (node->node_num[0] > max_node)
            max_node = node->node_num[0];
        if (node->node_num[1] > max_node)
            max_node = node->node_num[1];
    } RADIX_WALK_END;

    tab->radix->num_added_node += max_node;
    return (ISC_R_SUCCESS);
}

void
dns_iptable_attach(dns_iptable_t *source, dns_iptable_t **target) {
    REQUIRE(DNS_IPTABLE_VALID(source));
    isc_refcount_increment(&source->refcount, NULL);
    *target = source;
}

void
dns_iptable_detach(dns_iptable_t **tabp) {
    dns_iptable_t *tab = *tabp;
    unsigned int refs;
    REQUIRE(DNS_IPTABLE_VALID(tab));
    isc_refcount_decrement(&tab->refcount, &refs);
    if (refs == 0)
        destroy_iptable(tab);
    *tabp = NULL;
}

static void
destroy_iptable(dns_iptable_t *dtab) {

    REQUIRE(DNS_IPTABLE_VALID(dtab));

    if (dtab->radix != NULL) {
        isc_radix_destroy(dtab->radix, NULL);
        dtab->radix = NULL;
    }

    isc_refcount_destroy(&dtab->refcount);
    dtab->magic = 0;
    isc_mem_put(dtab->mctx, dtab, sizeof(*dtab));
}