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tinyproxy/src/acl.c
Mukund Sivaraman 919eedc7f9 Remove inline keyword from static functions 
The compiler inlines static functions as necessary anyway.
No more inline keywords exist in Tinyproxy source code. We want to
avoid using this keyword anyway.
2009-09-20 13:58:50 +05:30

352 lines
11 KiB
C
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/* tinyproxy - A fast light-weight HTTP proxy
* Copyright (C) 2000, 2002 Robert James Kaes <rjkaes@users.sourceforge.net>
*
* 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 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
*/
/* 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.
*/
#include "main.h"
#include "acl.h"
#include "heap.h"
#include "log.h"
#include "network.h"
#include "sock.h"
#include "vector.h"
/* Define how long an IPv6 address is in bytes (128 bits, 16 bytes) */
#define IPV6_LEN 16
enum acl_type {
ACL_STRING,
ACL_NUMERIC,
};
/*
* Hold the information about a particular access control. We store
* whether it's an ALLOW or DENY entry, and also whether it's a string
* entry (like a domain name) or an IP entry.
*/
struct acl_s {
acl_access_t access;
enum acl_type type;
union {
char *string;
struct {
unsigned char octet[IPV6_LEN];
unsigned char mask[IPV6_LEN];
} ip;
} address;
};
/*
* All the access lists are stored in a vector.
*/
static vector_t access_list = NULL;
/*
* Fills in the netmask array given a numeric value.
*
* Returns:
* 0 on success
* -1 on failure (invalid mask value)
*
*/
static int
fill_netmask_array (char *bitmask_string, unsigned char array[],
unsigned int len)
{
unsigned int i;
long int mask;
char *endptr;
errno = 0; /* to distinguish success/failure after call */
mask = strtol (bitmask_string, &endptr, 10);
/* check for various conversion errors */
if ((errno == ERANGE && (mask == LONG_MIN || mask == LONG_MAX))
|| (errno != 0 && mask == 0) || (endptr == bitmask_string))
return -1;
/* valid range for a bit mask */
if (mask < 0 || mask > (8 * len))
return -1;
/* we have a valid range to fill in the array */
for (i = 0; i != len; ++i) {
if (mask >= 8) {
array[i] = 0xff;
mask -= 8;
} else if (mask > 0) {
array[i] = (unsigned char) (0xff << (8 - mask));
mask = 0;
} else {
array[i] = 0;
}
}
return 0;
}
/*
* 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)
{
struct acl_s acl;
int ret;
char *p, ip_dst[IPV6_LEN];
assert (location != NULL);
/*
* If the access list has not been set up, create it.
*/
if (!access_list) {
access_list = vector_create ();
if (!access_list) {
log_message (LOG_ERR,
"Unable to allocate memory for access list");
return -1;
}
}
/*
* Start populating the access control structure.
*/
memset (&acl, 0, sizeof (struct acl_s));
acl.access = access_type;
/*
* Check for a valid IP address (the simplest case) first.
*/
if (full_inet_pton (location, ip_dst) > 0) {
acl.type = ACL_NUMERIC;
memcpy (acl.address.ip.octet, ip_dst, IPV6_LEN);
memset (acl.address.ip.mask, 0xff, IPV6_LEN);
} else {
/*
* At this point we're either a hostname or an
* IP address with a slash.
*/
p = strchr (location, '/');
if (p != NULL) {
/*
* We have a slash, so it's intended to be an
* IP address with mask
*/
*p = '\0';
if (full_inet_pton (location, ip_dst) <= 0)
return -1;
acl.type = ACL_NUMERIC;
memcpy (acl.address.ip.octet, ip_dst, IPV6_LEN);
if (fill_netmask_array
(p + 1, &(acl.address.ip.mask[0]), IPV6_LEN)
< 0)
return -1;
} else {
/* In all likelihood a string */
acl.type = ACL_STRING;
acl.address.string = safestrdup (location);
if (!acl.address.string)
return -1;
}
}
/*
* Add the entry and then clean up.
*/
ret = vector_append (access_list, &acl, sizeof (struct acl_s));
safefree (acl.address.string);
return ret;
}
/*
* This function is called whenever a "string" access control is found in
* the ACL. From here we do both a text based string comparison, along with
* a reverse name lookup comparison of the IP addresses.
*
* Return: 0 if host is denied
* 1 if host is allowed
* -1 if no tests match, so skip
*/
static int
acl_string_processing (struct acl_s *acl,
const char *ip_address, const char *string_address)
{
int match;
struct addrinfo hints, *res, *ressave;
size_t test_length, match_length;
char ipbuf[512];
assert (acl && acl->type == ACL_STRING);
assert (ip_address && strlen (ip_address) > 0);
assert (string_address && strlen (string_address) > 0);
/*
* If the first character of the ACL string is a period, we need to
* do a string based test only; otherwise, we can do a reverse
* lookup test as well.
*/
if (acl->address.string[0] != '.') {
memset (&hints, 0, sizeof (struct addrinfo));
hints.ai_family = AF_UNSPEC;
hints.ai_socktype = SOCK_STREAM;
if (getaddrinfo (acl->address.string, NULL, &hints, &res) != 0)
goto STRING_TEST;
ressave = res;
match = FALSE;
do {
get_ip_string (res->ai_addr, ipbuf, sizeof (ipbuf));
if (strcmp (ip_address, ipbuf) == 0) {
match = TRUE;
break;
}
} while ((res = res->ai_next) != NULL);
freeaddrinfo (ressave);
if (match) {
if (acl->access == ACL_DENY)
return 0;
else
return 1;
}
}
STRING_TEST:
test_length = strlen (string_address);
match_length = strlen (acl->address.string);
/*
* If the string length is shorter than AC string, return a -1 so
* that the "driver" will skip onto the next control in the list.
*/
if (test_length < match_length)
return -1;
if (strcasecmp
(string_address + (test_length - match_length),
acl->address.string) == 0) {
if (acl->access == ACL_DENY)
return 0;
else
return 1;
}
/* Indicate that no tests succeeded, so skip to next control. */
return -1;
}
/*
* Compare the supplied numeric IP address with the supplied ACL structure.
*
* Return:
* 1 IP address is allowed
* 0 IP address is denied
* -1 neither allowed nor denied.
*/
static int check_numeric_acl (const struct acl_s *acl, const char *ip)
{
uint8_t addr[IPV6_LEN], x, y;
int i;
assert (acl && acl->type == ACL_NUMERIC);
assert (ip && strlen (ip) > 0);
if (full_inet_pton (ip, &addr) <= 0)
return -1;
for (i = 0; i != IPV6_LEN; ++i) {
x = addr[i] & acl->address.ip.mask[i];
y = acl->address.ip.octet[i] & acl->address.ip.mask[i];
/* If x and y don't match, the IP addresses don't match */
if (x != y)
return 0;
}
/* The addresses match, return the permission */
return (acl->access == ACL_ALLOW);
}
/*
* Checks whether a connection is allowed.
*
* Returns:
* 1 if allowed
* 0 if denied
*/
int check_acl (const char *ip, const char *host)
{
struct acl_s *acl;
int perm = 0;
size_t i;
assert (ip != NULL);
assert (host != NULL);
/*
* If there is no access list allow everything.
*/
if (!access_list)
return 1;
for (i = 0; i != (size_t) vector_length (access_list); ++i) {
acl = (struct acl_s *) vector_getentry (access_list, i, NULL);
switch (acl->type) {
case ACL_STRING:
perm = acl_string_processing (acl, ip, host);
break;
case ACL_NUMERIC:
if (ip[0] == '\0')
continue;
perm = check_numeric_acl (acl, ip);
break;
}
/*
* Check the return value too see if the IP address is
* allowed or denied.
*/
if (perm == 0)
break;
else if (perm == 1)
return perm;
}
/*
* Deny all connections by default.
*/
log_message (LOG_NOTICE, "Unauthorized connection from \"%s\" [%s].",
host, ip);
return 0;
}
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