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/* $Id: acl.c,v 1.3 2001-05-23 17:57:22 rjkaes Exp $
*
* This system handles Access Control for use of this daemon. A list of
* domains, or IP addresses (including IP blocks) are stored in a list
* which is then used to compare incoming connections.
*
* Copyright (C) 2000 Robert James Kaes (rjkaes@flarenet.com)
*
* 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 2, 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.
*/
#include "tinyproxy.h"
#include <ctype.h>
#include "acl.h"
#include "log.h"
#include "sock.h"
struct acl_s {
acl_access_t access;
enum { ACL_STRING, ACL_NUMERIC } type;
char *location;
int netmask;
struct acl_s *next;
};
static struct acl_s *access_list = NULL;
/*
* Take a netmask number (between 0 and 32) and returns a network ordered
* value for comparison. Somebody please clean this up. :)
*/
static in_addr_t make_netmask(int netmask_num)
{
static in_addr_t netmasks[] = {
0x00000000, 0x80000000, 0xc0000000, 0xe0000000,
0xf8000000, 0xfc000000, 0xfe000000, 0xff000000,
0xff800000, 0xffc00000, 0xffe00000, 0xfff00000,
0xfff00000, 0xfff80000, 0xfffc0000, 0xfffe0000,
0xffff0000, 0xffff8000, 0xffffc000, 0xffffe000,
0xfffff000, 0xfffff800, 0xfffffc00, 0xfffffe00,
0xffffff00, 0xffffff80, 0xffffffc0, 0xffffffe0,
0xfffffff0, 0xfffffff8, 0xfffffffc, 0xfffffffe,
0xffffffff
};
assert(netmask_num >= 0 && netmask_num <= 32);
return htonl(netmasks[netmask_num]);
}
/*
* Inserts a new access control into the list. The function will figure out
* whether the location is an IP address (with optional netmask) or a
* domain name.
*
* Returns:
* -1 on failure
* 0 otherwise.
*/
int insert_acl(char *location, acl_access_t access_type)
{
unsigned int i;
struct acl_s **rev_acl_ptr, *acl_ptr, *new_acl_ptr;
char *nptr;
assert(location != NULL);
/*
* First check to see if the location is a string or numeric.
*/
for (i = 0; i < strlen(location); i++) {
if (isdigit(location[i]) != 0 && location[i] != '.') {
break;
}
}
/*
* Add a new ACL to the list.
*/
rev_acl_ptr = &access_list;
acl_ptr = access_list;
while (acl_ptr) {
rev_acl_ptr = &acl_ptr->next;
acl_ptr = acl_ptr->next;
}
new_acl_ptr = malloc(sizeof(struct acl_s));
if (!new_acl_ptr) {
return -1;
}
new_acl_ptr->access = access_type;
if (i != strlen(location)) {
/* We did break early, so this a numeric location.
* Check for a netmask.
*/
new_acl_ptr->type = ACL_NUMERIC;
nptr = strchr(location, '/');
if (nptr) {
*nptr++ = '\0';
new_acl_ptr->netmask = atoi(nptr);
if (new_acl_ptr->netmask < 0 || new_acl_ptr->netmask > 32) {
safefree(new_acl_ptr);
return -1;
}
} else {
new_acl_ptr->netmask = 32;
}
} else {
new_acl_ptr->type = ACL_STRING;
new_acl_ptr->netmask = 32;
}
new_acl_ptr->location = strdup(location);
if (!new_acl_ptr->location) {
safefree(new_acl_ptr);
return -1;
}
*rev_acl_ptr = new_acl_ptr;
new_acl_ptr->next = acl_ptr;
return 0;
}
/*
* Checks where file descriptor is allowed.
*
* Returns:
* 1 if allowed
* 0 if denied
* -1 if error
*/
int check_acl(int fd)
{
struct acl_s *aclptr;
char ip_address[PEER_IP_LENGTH];
char string_address[PEER_STRING_LENGTH];
assert(fd >= 0);
/*
* If there is no access list allow everything.
*/
aclptr = access_list;
if (!aclptr)
return 1;
/*
* Get the IP address and the string domain.
*/
getpeer_ip(fd, ip_address);
getpeer_string(fd, string_address);
while (aclptr) {
if (aclptr->type == ACL_STRING) {
int test_length = strlen(string_address);
int match_length = strlen(aclptr->location);
if (test_length < match_length) {
aclptr = aclptr->next;
continue;
}
if (strcasecmp(string_address + (test_length - match_length), aclptr->location) == 0) {
if (aclptr->access == ACL_DENY) {
log(LOG_NOTICE, "Unauthorized access from %s", string_address);
return 0;
} else {
return 1;
}
}
} else {
struct in_addr test_addr, match_addr;
in_addr_t netmask_addr;
if (ip_address[0] == 0) {
aclptr = aclptr->next;
continue;
}
inet_aton(ip_address, &test_addr);
inet_aton(aclptr->location, &match_addr);
netmask_addr = make_netmask(aclptr->netmask);
if ((test_addr.s_addr & netmask_addr) == (match_addr.s_addr & netmask_addr)) {
if (aclptr->access == ACL_DENY) {
log(LOG_NOTICE, "Unauthorized access from %s", ip_address);
return 0;
} else {
return 1;
}
}
}
/*
* Dropped through... go on to the next one.
*/
aclptr = aclptr->next;
}
/*
* Deny all connections by default.
*/
log(LOG_NOTICE, "Unauthorized connection from %s [%s]", string_address, ip_address);
return 0;
}
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