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/* Copyright (C) 2011 CZ.NIC, z.s.p.o. <knot-dns@labs.nic.cz>
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <config.h>
#include <string.h>
#include <stdlib.h>
#include <assert.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <limits.h>
#include <stdbool.h>
#include "common/errcode.h"
#include "common/acl.h"
#include "libknot/util/endian.h"
static inline uint32_t ipv4_chunk(const sockaddr_t *a)
{
/* Stored as big end first. */
return a->addr4.sin_addr.s_addr;
}
static inline uint32_t ipv6_chunk(const sockaddr_t *a, uint8_t idx)
{
/* Is byte array, 4x 32bit value. */
return ((uint32_t *)&a->addr6.sin6_addr)[idx];
}
static inline uint32_t ip_chunk(const sockaddr_t *a, uint8_t idx)
{
if (sockaddr_family(a) == AF_INET)
return ipv4_chunk(a);
return ipv6_chunk(a, idx);
}
/*! \brief Compare chunks using given mask. */
static int cmp_chunk(const sockaddr_t *a1, const sockaddr_t *a2,
uint8_t idx, uint32_t mask)
{
const uint32_t c1 = ip_chunk(a1, idx) & mask;
const uint32_t c2 = ip_chunk(a2, idx) & mask;
if (c1 > c2)
return 1;
if (c1 < c2)
return -1;
return 0;
}
/*!
* \brief Calculate bitmask for byte array from the MSB.
*
* \note i.e. 8 means top 8 bits set, 11111111000000000000000000000000
*
* \param nbits number of bits set to 1
* \return mask
*/
static uint32_t acl_fill_mask32(short nbits)
{
assert(nbits >= 0 && nbits <= 32);
uint32_t r = 0;
for (char i = 0; i < nbits; ++i) {
r |= 1 << (31 - i);
}
/* Make sure the mask is in network byte order. */
return htonl(r);
}
static int acl_compare(const sockaddr_t *a1, const sockaddr_t *a2)
{
int ret = 0;
uint32_t mask = 0xffffffff;
short mask_bits = a1->prefix;
const short chunk_bits = sizeof(mask) * CHAR_BIT;
/* Check different length, IPv4 goes first. */
if (a1->len != a2->len) {
if (a1->len < a2->len)
return -1;
else
return 1;
}
/* At most 4xchunk_bits for IPv6 */
unsigned i = 0;
while (ret == 0 && mask_bits > 0) {
/* Compute mask for current chunk. */
if (mask_bits <= chunk_bits) {
mask = acl_fill_mask32(mask_bits);
mask_bits = 0; /* Last chunk */
} else {
mask_bits -= chunk_bits;
}
/* Empty mask - shortcut, we're done. */
if (mask > 0)
ret = cmp_chunk(a1, a2, i, mask);
++i;
}
return ret;
}
acl_t *acl_new()
{
acl_t *acl = malloc(sizeof(acl_t));
if (acl == NULL) {
return NULL;
}
memset(acl, 0, sizeof(acl_t));
init_list(acl);
return acl;
}
void acl_delete(acl_t **acl)
{
if (acl == NULL || *acl == NULL) {
return;
}
acl_truncate(*acl);
/* Free ACL. */
free(*acl);
*acl = 0;
}
int acl_insert(acl_t *acl, const sockaddr_t *addr, void *val)
{
if (acl == NULL || addr == NULL) {
return KNOT_EINVAL;
}
/* Create new match. */
acl_match_t *key = malloc(sizeof(acl_match_t));
if (key == NULL) {
return KNOT_ENOMEM;
}
memcpy(&key->addr, addr, sizeof(sockaddr_t));
key->val = val;
/* Sort by prefix length.
* This way the longest prefix match always goes first.
*/
if (EMPTY_LIST(*acl)) {
add_head(acl, &key->n);
} else {
bool inserted = false;
acl_match_t *cur = NULL, *prev = NULL;
WALK_LIST(cur, *acl) {
/* Next node prefix is equal/shorter than current key.
* This means we need to insert before the next node.
*/
if (cur->addr.prefix < addr->prefix) {
if (prev == NULL) { /* First node. */
add_head(acl, &key->n);
} else {
insert_node(&key->n, &prev->n);
}
inserted = true;
break;
}
prev = cur;
}
/* Didn't find any better fit, insert at the end. */
if (!inserted) {
add_tail(acl, &key->n);
}
}
return KNOT_EOK;
}
acl_match_t* acl_find(acl_t *acl, const sockaddr_t *addr)
{
if (acl == NULL || addr == NULL) {
return NULL;
}
acl_match_t *cur = NULL;
WALK_LIST(cur, *acl) {
/* Since the list is sorted by prefix length, the first match
* is guaranteed to be longest prefix match (most precise).
*/
if (acl_compare(&cur->addr, addr) == 0) {
return cur;
}
}
return NULL;
}
void acl_truncate(acl_t *acl)
{
if (acl == NULL) {
return;
}
WALK_LIST_FREE(*acl);
}
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