iptable.c   [plain text]

/*
 * Copyright (C) 2007-2009  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: iptable.c,v 1.15 2009/02/18 23:47:48 tbox Exp $ */

#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));
}