--- /dev/null
+// $Id: ifspec.c,v 1.1.4.1 2003/11/21 16:01:09 ensc Exp $
+
+// Copyright (C) 2003 Enrico Scholz <enrico.scholz@informatik.tu-chemnitz.de>
+// based on ifspec.cc by Jacques Gelinas
+//
+// 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, 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.
+
+/*
+ Prints the specs of a network device in shell like form
+
+ ADDR=
+ NETMASK=
+ BCAST=
+*/
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <ctype.h>
+#include <unistd.h>
+#include <sys/socket.h>
+#include <sys/ioctl.h>
+#include <netinet/in.h>
+#include <net/if.h>
+
+static void usage()
+{
+ fprintf (stderr,"ifspec version %s\n",VERSION);
+ fprintf (stderr
+ ,"ifspec network-device [ ipaddr netmask broadcast ]\n"
+ "prints device specification in a shell usable way\n");
+ exit (-1);
+}
+
+static int ifconfig_ioctl(
+ int fd,
+ const char *ifname,
+ int cmd,
+ struct ifreq *ifr)
+{
+ strcpy(ifr->ifr_name, ifname);
+ return ioctl(fd, cmd,ifr);
+}
+
+static unsigned long ip_cnv (const char *str)
+{
+ const char *start_str = str;
+ unsigned tb[4];
+ int no = 0;
+ unsigned long ret;
+
+ memset (tb,-1,sizeof(tb));
+ while (*str != '\0' && no < 4){
+ if (isdigit(*str)){
+ int val = atoi(str);
+ if (val > 255) break;
+ tb[no++] = val;
+ while (isdigit(*str)) str++;
+ if (*str == '.'){
+ str++;
+ }else{
+ break;
+ }
+ }else{
+ break;
+ }
+ }
+
+ ret = (tb[0] << 24) | (tb[1]<<16) | (tb[2] << 8) | tb[3];
+ if (no != 4 || *str != '\0'){
+ fprintf (stderr,"Invalid IP number or netmask: %s\n",start_str);
+ ret = 0xffffffff;
+ }
+ return ret;
+}
+
+
+/*
+ Fetch the IP number of an interface from the kernel.
+ Assume the device is already available in the kernel
+ Return -1 if any error.
+*/
+int ifconfig_print (
+ const char *ifname,
+ const char *addrstr,
+ const char *maskstr,
+ const char *bcaststr)
+{
+ int ret = -1;
+ int skfd = socket(AF_INET, SOCK_DGRAM, 0);
+ if (skfd != -1){
+ struct ifreq ifr;
+ struct {
+ unsigned long addr;
+ unsigned long mask;
+ } solved = {0,0};
+ if (addrstr != NULL && addrstr[0] != '\0'){
+ printf ("ADDR=%s\n",addrstr);
+ solved.addr = ip_cnv (addrstr);
+ }else if (ifconfig_ioctl(skfd,ifname,SIOCGIFADDR, &ifr) >= 0){
+ struct sockaddr_in *sin = (struct sockaddr_in*)&ifr.ifr_addr;
+ unsigned long addr = ntohl(sin->sin_addr.s_addr);
+ printf ("ADDR=%lu.%lu.%lu.%lu\n"
+ ,(addr>>24)&0xff
+ ,(addr>>16)&0xff
+ ,(addr>>8)&0xff
+ ,addr&0xff);
+ solved.addr = addr;
+ ret = 0;
+ }
+ else {
+ perror("ioctl(SIOCGIFADDR)");
+ }
+
+ if (maskstr != NULL && maskstr[0] != '\0'){
+ printf ("NETMASK=%s\n",maskstr);
+ solved.mask = ip_cnv (maskstr);
+ }else if (ifconfig_ioctl(skfd,ifname,SIOCGIFNETMASK, &ifr) >= 0){
+ struct sockaddr_in *sin = (struct sockaddr_in*)&ifr.ifr_addr;
+ unsigned long addr = ntohl(sin->sin_addr.s_addr);
+ printf ("NETMASK=%lu.%lu.%lu.%lu\n"
+ ,(addr>>24)&0xff
+ ,(addr>>16)&0xff
+ ,(addr>>8)&0xff
+ ,addr&0xff);
+ solved.mask = addr;
+ ret = 0;
+ }
+ else {
+ perror("ioctl(SIOCGIFNETMASK)");
+ }
+
+ if (bcaststr != NULL && bcaststr[0] != '\0'){
+ printf ("BCAST=%s\n",bcaststr);
+ }else if (ifconfig_ioctl(skfd,ifname,SIOCGIFBRDADDR, &ifr) >= 0){
+ struct sockaddr_in *sin = (struct sockaddr_in*)&ifr.ifr_addr;
+ unsigned long addr = ntohl(sin->sin_addr.s_addr);
+ printf ("BCAST=%lu.%lu.%lu.%lu\n"
+ ,(addr>>24)&0xff
+ ,(addr>>16)&0xff
+ ,(addr>>8)&0xff
+ ,addr&0xff);
+ ret = 0;
+ }else if (solved.addr!=0 && solved.mask!=0) {
+ // Can't get it from the kernel, compute it from the IP
+ // and the netmask
+ unsigned long addr = (solved.addr & solved.mask)
+ | ~solved.mask;
+ printf ("BCAST=%lu.%lu.%lu.%lu\n"
+ ,(addr>>24)&0xff
+ ,(addr>>16)&0xff
+ ,(addr>>8)&0xff
+ ,addr&0xff);
+
+ }
+ close (skfd);
+ }
+ return ret;
+}
+
+
+int main (int argc, char *argv[])
+{
+ int ret = -1;
+ if (argc < 2){
+ usage();
+ }else{
+ const char *addrstr = argc >= 3 ? argv[2] : NULL;
+ const char *maskstr = argc >= 4 ? argv[3] : NULL;
+ const char *bcaststr = argc >= 5 ? argv[4] : NULL;
+ ret = ifconfig_print (argv[1],addrstr,maskstr,bcaststr);
+ }
+ return ret;
+}
+
+
+
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