mirror of
https://github.com/openwrt/openwrt.git
synced 2024-12-25 16:31:13 +00:00
127 lines
3.0 KiB
C
127 lines
3.0 KiB
C
/*
|
|
* Utility used to calculate the 6rd subnet.
|
|
*
|
|
* Copyright 2012, Stéphan Kochen <stephan@kochen.nl>
|
|
*
|
|
* 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., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
|
|
*/
|
|
|
|
#include <stdio.h>
|
|
#include <stdlib.h>
|
|
#include <string.h>
|
|
#include <sys/errno.h>
|
|
#include <arpa/inet.h>
|
|
#include <netinet/in.h>
|
|
|
|
#define INET_PREFIXSTRLEN (INET_ADDRSTRLEN+3)
|
|
#define INET6_PREFIXSTRLEN (INET6_ADDRSTRLEN+4)
|
|
|
|
static void print_usage()
|
|
{
|
|
fprintf(stderr, "Usage: 6rdcalc <v6 prefix>/<mask> <v4 address>/<mask>\n");
|
|
exit(1);
|
|
}
|
|
|
|
static void print_error()
|
|
{
|
|
fprintf(stderr, "%s", strerror(errno));
|
|
exit(1);
|
|
}
|
|
|
|
static void parse_str(int af, char *str, void *addr, unsigned long *mask)
|
|
{
|
|
int ret;
|
|
char *slash;
|
|
|
|
/* Split the address at the slash. */
|
|
if ((slash = strchr(str, '/')) == NULL)
|
|
print_usage();
|
|
*slash = '\0';
|
|
|
|
/* Parse the address. */
|
|
if ((ret = inet_pton(af, str, addr)) != 1) {
|
|
if (ret == 0)
|
|
print_usage();
|
|
else
|
|
print_error();
|
|
}
|
|
|
|
/* Parse the mask. */
|
|
*mask = strtoul(slash+1, NULL, 10);
|
|
if ((af == AF_INET && *mask > 32) ||
|
|
(af == AF_INET6 && *mask > 128))
|
|
print_usage();
|
|
}
|
|
|
|
int main(int argc, const char **argv)
|
|
{
|
|
char v6str[INET6_PREFIXSTRLEN], v4str[INET_PREFIXSTRLEN];
|
|
struct in6_addr v6;
|
|
struct in_addr v4;
|
|
unsigned long v6it, v4it, mask;
|
|
unsigned char *byte4, *byte6;
|
|
unsigned char bit4, bit6;
|
|
|
|
/* Check parameters. */
|
|
if (argc != 3)
|
|
print_usage();
|
|
|
|
/* Parse the v6 address. */
|
|
strncpy(v6str, argv[1], INET6_PREFIXSTRLEN);
|
|
v6str[INET6_PREFIXSTRLEN-1] = '\0';
|
|
parse_str(AF_INET6, v6str, &v6, &v6it);
|
|
|
|
/* Parse the v4 address */
|
|
strncpy(v4str, argv[2], INET_PREFIXSTRLEN);
|
|
v6str[INET_PREFIXSTRLEN-1] = '\0';
|
|
parse_str(AF_INET, v4str, &v4, &v4it);
|
|
|
|
/* Check if the combined mask is within bounds. */
|
|
mask = (32 - v4it) + v6it;
|
|
if (mask > 128)
|
|
print_usage();
|
|
|
|
/* Combine the addresses. */
|
|
while (v4it < 32) {
|
|
byte6 = (unsigned char *)(&v6.s6_addr) + (v6it >> 3);
|
|
byte4 = (unsigned char *)(&v4.s_addr) + (v4it >> 3);
|
|
bit6 = 128 >> (v6it & 0x07);
|
|
bit4 = 128 >> (v4it & 0x07);
|
|
|
|
if (*byte4 & bit4)
|
|
*byte6 |= bit6;
|
|
else
|
|
*byte6 &= ~bit6;
|
|
|
|
v4it++; v6it++;
|
|
}
|
|
|
|
/* Clear remaining bits. */
|
|
while (v6it < 128) {
|
|
byte6 = (unsigned char *)(&v6.s6_addr) + (v6it >> 2);
|
|
bit6 = 128 >> (v6it & 0x07);
|
|
|
|
*byte6 &= ~bit6;
|
|
|
|
v6it++;
|
|
}
|
|
|
|
/* Print the subnet prefix. */
|
|
if (inet_ntop(AF_INET6, &v6, v6str, sizeof(v6str)) == NULL)
|
|
print_error();
|
|
printf("%s/%lu\n", v6str, mask);
|
|
return 0;
|
|
}
|