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/*
$Header: /cvs/src/chrony/addrfilt.c,v 1.8 2002/02/28 23:27:08 richard Exp $
=======================================================================
chronyd/chronyc - Programs for keeping computer clocks accurate.
**********************************************************************
* Copyright (C) Richard P. Curnow 1997,1998,1999,2000,2001,2002,2005
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of version 2 of the GNU General Public License as
* published by the Free Software Foundation.
*
* 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, write to the Free Software Foundation, Inc.,
* 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*
**********************************************************************
=======================================================================
This module provides a set of routines for checking IP addresses
against a set of rules and deciding whether they are allowed or
disallowed.
*/
#include "sysincl.h"
#include "addrfilt.h"
#include "memory.h"
/* Define the number of bits which are stripped off per level of
indirection in the tables */
#define NBITS 4
/* Define the table size */
#define TABLE_SIZE (1UL<<NBITS)
typedef enum {DENY, ALLOW, AS_PARENT} State;
typedef struct _TableNode {
State state;
struct _TableNode *extended;
} TableNode;
struct ADF_AuthTableInst {
TableNode base;
};
/* ================================================== */
inline static unsigned long
get_subnet(unsigned long addr)
{
return (addr >> (32-NBITS)) & ((1UL<<NBITS) - 1);
}
/* ================================================== */
inline static unsigned long
get_residual(unsigned long addr)
{
return (addr << NBITS);
}
/* ================================================== */
ADF_AuthTable
ADF_CreateTable(void)
{
ADF_AuthTable result;
result = MallocNew(struct ADF_AuthTableInst);
/* Default is that nothing is allowed */
result->base.state = DENY;
result->base.extended = NULL;
return result;
}
/* ================================================== */
/* This function deletes all definitions of child nodes, in effect
pruning a whole subnet definition back to a single parent
record. */
static void
close_node(TableNode *node)
{
int i;
TableNode *child_node;
if (node->extended != NULL) {
for (i=0; i<TABLE_SIZE; i++) {
child_node = &(node->extended[i]);
close_node(child_node);
}
Free(node->extended);
node->extended = NULL;
}
return;
}
/* ================================================== */
/* Allocate the extension field in a node, and set all the children's
states to default to that of the node being extended */
static void
open_node(TableNode *node)
{
int i;
TableNode *child_node;
if (node->extended == NULL) {
node->extended = MallocArray(struct _TableNode, TABLE_SIZE);
for (i=0; i<TABLE_SIZE; i++) {
child_node = &(node->extended[i]);
child_node->state = AS_PARENT;
child_node->extended = NULL;
}
}
return;
}
/* ================================================== */
static ADF_Status
set_subnet(TableNode *start_node,
unsigned long ip,
int subnet_bits,
State new_state,
int delete_children)
{
int bits_to_go;
unsigned long residual;
unsigned long subnet;
TableNode *node;
bits_to_go = subnet_bits;
residual = ip;
node = start_node;
if ((subnet_bits < 0) ||
(subnet_bits > 32)) {
return ADF_BADSUBNET;
} else {
if ((bits_to_go & (NBITS-1)) == 0) {
while (bits_to_go > 0) {
subnet = get_subnet(residual);
residual = get_residual(residual);
if (!(node->extended)) {
open_node(node);
}
node = &(node->extended[subnet]);
bits_to_go -= NBITS;
}
if (delete_children) {
close_node(node);
}
node->state = new_state;
} else { /* Have to set multiple entries */
int N, i, j;
TableNode *this_node;
while (bits_to_go >= NBITS) {
subnet = get_subnet(residual);
residual = get_residual(residual);
if (!(node->extended)) {
open_node(node);
}
node = &(node->extended[subnet]);
bits_to_go -= NBITS;
}
/* How many subnet entries to set : 1->8, 2->4, 3->2 */
N = 1 << (NBITS-bits_to_go);
subnet = get_subnet(residual);
if (!(node->extended)) {
open_node(node);
}
for (i=subnet, j=0; j<N; i++, j++) {
this_node = &(node->extended[i]);
if (delete_children) {
close_node(this_node);
}
this_node->state = new_state;
}
}
return ADF_SUCCESS;
}
}
/* ================================================== */
ADF_Status
ADF_Allow(ADF_AuthTable table,
unsigned long ip,
int subnet_bits)
{
return set_subnet(&(table->base), ip, subnet_bits, ALLOW, 0);
}
/* ================================================== */
ADF_Status
ADF_AllowAll(ADF_AuthTable table,
unsigned long ip,
int subnet_bits)
{
return set_subnet(&(table->base), ip, subnet_bits, ALLOW, 1);
}
/* ================================================== */
ADF_Status
ADF_Deny(ADF_AuthTable table,
unsigned long ip,
int subnet_bits)
{
return set_subnet(&(table->base), ip, subnet_bits, DENY, 0);
}
/* ================================================== */
ADF_Status
ADF_DenyAll(ADF_AuthTable table,
unsigned long ip,
int subnet_bits)
{
return set_subnet(&(table->base), ip, subnet_bits, DENY, 1);
}
/* ================================================== */
void
ADF_DestroyTable(ADF_AuthTable table)
{
close_node(&(table->base));
Free(table);
}
/* ================================================== */
static int
check_ip_in_node(TableNode *start_node, unsigned long ip)
{
unsigned long residual, subnet;
int result = 0;
int finished = 0;
TableNode *node;
State state=DENY;
node = start_node;
residual = ip;
do {
if (node->state != AS_PARENT) {
state = node->state;
}
if (node->extended) {
subnet = get_subnet(residual);
residual = get_residual(residual);
node = &(node->extended[subnet]);
} else {
/* Make decision on this node */
finished = 1;
}
} while (!finished);
switch (state) {
case ALLOW:
result = 1;
break;
case DENY:
result = 0;
break;
case AS_PARENT:
assert(0);
break;
}
return result;
}
/* ================================================== */
int
ADF_IsAllowed(ADF_AuthTable table,
unsigned long ip)
{
return check_ip_in_node(&(table->base), ip);
}
/* ================================================== */
#if defined TEST
static void print_node(TableNode *node, unsigned long addr, int shift, int subnet_bits)
{
unsigned long new_addr;
int i;
TableNode *sub_node;
for (i=0; i<subnet_bits; i++) putchar(' ');
printf("%d.%d.%d.%d/%d : %s\n",
((addr >> 24) & 255),
((addr >> 16) & 255),
((addr >> 8) & 255),
((addr ) & 255),
subnet_bits,
(node->state == ALLOW) ? "allow" :
(node->state == DENY) ? "deny" : "as parent");
if (node->extended) {
for (i=0; i<16; i++) {
sub_node = &((*(node->extended))[i]);
new_addr = addr | ((unsigned long) i << shift);
print_node(sub_node, new_addr, shift - 4, subnet_bits + 4);
}
}
return;
}
static void print_table(ADF_AuthTable table)
{
unsigned long addr = 0;
int shift = 28;
int subnet_bits = 0;
print_node(&table->base, addr, shift, subnet_bits);
return;
}
/* ================================================== */
int main (int argc, char **argv)
{
ADF_AuthTable table;
table = ADF_CreateTable();
ADF_Allow(table, 0x7e800000, 9);
ADF_Deny(table, 0x7ecc0000, 14);
/* ADF_Deny(table, 0x7f000001, 32); */
/* ADF_Allow(table, 0x7f000000, 8); */
print_table(table);
ADF_DestroyTable(table);
return 0;
}
#endif /* defined TEST */
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