mask2prefix.c (1590B)
1 // $Id$ --*- c++ -*-- 2 3 // Copyright (C) 2003 Enrico Scholz <enrico.scholz@informatik.tu-chemnitz.de> 4 // 5 // This program is free software; you can redistribute it and/or modify 6 // it under the terms of the GNU General Public License as published by 7 // the Free Software Foundation; version 2 of the License. 8 // 9 // This program is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU General Public License for more details. 13 // 14 // You should have received a copy of the GNU General Public License 15 // along with this program; if not, write to the Free Software 16 // Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. 17 18 19 #ifdef HAVE_CONFIG_H 20 # include <config.h> 21 #endif 22 23 #include "util.h" 24 #include <stdlib.h> 25 26 static inline void 27 showHelp(int fd, int exit_code) 28 { 29 WRITE_MSG(fd, 30 "Usage: mask2prefix <mask>\n"); 31 exit(exit_code); 32 } 33 34 int main(int argc, char *argv[]) 35 { 36 char *err_ptr, *ptr; 37 int len = 0; 38 size_t i; 39 40 if (argc!=2) showHelp(2,255); 41 42 ptr = argv[1]; 43 for (i=0; i<4; ++i) { 44 unsigned int val = strtol(ptr, &err_ptr, 10); 45 46 switch (*err_ptr) { 47 case '.' : 48 case '\0' : break; 49 default : 50 WRITE_MSG(2, "Invalid mask specified\n"); 51 return 255; 52 } 53 54 if (val>=0x100) { 55 WRITE_MSG(2, "Invalid mask specified\n"); 56 return 255; 57 } 58 59 while (val&0x80) { 60 ++len; 61 val <<= 1; 62 } 63 64 if (val!=0xff00) break; 65 66 ptr = err_ptr+1; 67 } 68 69 return len; 70 }