/* * * Connection Manager * * Copyright (C) 2007-2010 Intel Corporation. All rights reserved. * * This program is free software; you can redistribute it and/or modify * it under the terms of the GNU General Public License version 2 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., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA * */ #ifdef HAVE_CONFIG_H #include #endif #include #include static unsigned char netmask2prefixlen(const char *netmask) { unsigned char bits = 0; in_addr_t mask = inet_network(netmask); in_addr_t host = ~mask; /* a valid netmask must be 2^n - 1 */ if ((host & (host + 1)) != 0) return -1; for (; mask; mask <<= 1) ++bits; return bits; } int main(int argc, char *argv[]) { const char *masks[] = { "255.255.255.255", "255.255.255.0", "255.255.0.0", "255.0.0.0" }; struct in_addr addr; int i, len; for (i = 0; i < 4; i++) { printf("subnet %-16s prefixlen %u\n", masks[i], netmask2prefixlen(masks[i])); } printf("\n"); for (i = 0; i < 4; i++) { len = (i + 1) * 8; addr.s_addr = htonl(~(0xfffffffflu >> len)); printf("prefixlen %-2u netmask %s\n", len, inet_ntoa(addr)); } return 0; }