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/*
This file is part of GNUnet
(C) 2012, 2013 Christian Grothoff (and other contributing authors)
GNUnet 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, or (at your
option) any later version.
GNUnet 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 GNUnet; see the file COPYING. If not, write to the
Free Software Foundation, Inc., 59 Temple Place - Suite 330,
Boston, MA 02111-1307, USA.
*/
/**
* @file src/tun/regex.c
* @brief functions to convert IP networks to regexes
* @author Maximilian Szengel
*/
#include "platform.h"
#include "gnunet_util_lib.h"
#include "gnunet_tun_lib.h"
/**
* Create a string with binary IP notation for the given 'addr' in 'str'.
*
* @param af address family of the given 'addr'.
* @param addr address that should be converted to a string.
* struct in_addr * for IPv4 and struct in6_addr * for IPv6.
* @param str string that will contain binary notation of 'addr'. Expected
* to be at least 33 bytes long for IPv4 and 129 bytes long for IPv6.
*/
static void
iptobinstr (const int af, const void *addr, char *str)
{
int i;
switch (af)
{
case AF_INET:
{
uint32_t b = htonl (((struct in_addr *) addr)->s_addr);
str[32] = '\0';
str += 31;
for (i = 31; i >= 0; i--)
{
*str = (b & 1) + '0';
str--;
b >>= 1;
}
break;
}
case AF_INET6:
{
struct in6_addr b = *(const struct in6_addr *) addr;
str[128] = '\0';
str += 127;
for (i = 127; i >= 0; i--)
{
*str = (b.s6_addr[i / 8] & 1) + '0';
str--;
b.s6_addr[i / 8] >>= 1;
}
break;
}
}
}
/**
* Get the ipv4 network prefix from the given 'netmask'.
*
* @param netmask netmask for which to get the prefix len.
*
* @return length of ipv4 prefix for 'netmask'.
*/
static unsigned int
ipv4netmasktoprefixlen (const char *netmask)
{
struct in_addr a;
unsigned int len;
uint32_t t;
if (1 != inet_pton (AF_INET, netmask, &a))
return 0;
len = 32;
for (t = htonl (~a.s_addr); 0 != t; t >>= 1)
len--;
return len;
}
/**
* Create a regex in 'rxstr' from the given 'ip' and 'netmask'.
*
* @param ip IPv4 representation.
* @param netmask netmask for the ip.
* @param rxstr generated regex, must be at least GNUNET_REGEX_IPV4_REGEXLEN
* bytes long.
*/
void
GNUNET_TUN_ipv4toregexsearch (const struct in_addr *ip, const char *netmask,
char *rxstr)
{
unsigned int pfxlen;
pfxlen = ipv4netmasktoprefixlen (netmask);
iptobinstr (AF_INET, ip, rxstr);
rxstr[pfxlen] = '\0';
if (pfxlen < 32)
strcat (rxstr, "(0|1)+");
}
/**
* Create a regex in 'rxstr' from the given 'ipv6' and 'prefixlen'.
*
* @param ipv6 IPv6 representation.
* @param prefixlen length of the ipv6 prefix.
* @param rxstr generated regex, must be at least GNUNET_REGEX_IPV6_REGEXLEN
* bytes long.
*/
void
GNUNET_TUN_ipv6toregexsearch (const struct in6_addr *ipv6, unsigned int prefixlen,
char *rxstr)
{
iptobinstr (AF_INET6, ipv6, rxstr);
rxstr[prefixlen] = '\0';
if (prefixlen < 128)
strcat (rxstr, "(0|1)+");
}
/**
* Convert an exit policy to a regular expression. The exit policy
* specifies a set of subnets this peer is willing to serve as an
* exit for; the resulting regular expression will match the
* IPv4 address strings as returned by 'GNUNET_TUN_ipv4toregexsearch'.
*
* @param policy exit policy specification
* @return regular expression, NULL on error
*/
char *
GNUNET_TUN_ipv4policy2regex (const char *policy)
{
return GNUNET_strdup (policy);
}
/**
* Convert an exit policy to a regular expression. The exit policy
* specifies a set of subnets this peer is willing to serve as an
* exit for; the resulting regular expression will match the
* IPv4 address strings as returned by 'GNUNET_TUN_ipv4toregexsearch'.
*
* @param policy exit policy specification
* @return regular expression, NULL on error
*/
char *
GNUNET_TUN_ipv6policy2regex (const char *policy)
{
return GNUNET_strdup (policy);
}
/* end of regex.c */
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