112 lines
2.8 KiB
C
112 lines
2.8 KiB
C
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/* $Id: getgateway.c,v 1.4 2007/11/22 18:01:37 nanard Exp $ */
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/* libnatpmp
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* Copyright (c) 2007, Thomas BERNARD <miniupnp@free.fr>
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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#include <stdio.h>
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#include <ctype.h>
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#include <netinet/in.h>
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#include <sys/param.h>
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#ifdef BSD
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#include <stdlib.h>
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#include <sys/sysctl.h>
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#include <sys/socket.h>
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#include <net/route.h>
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#endif
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#include "getgateway.h"
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#ifdef __linux__
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int getdefaultgateway(in_addr_t * addr)
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{
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long d, g;
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char buf[256];
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int line = 0;
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FILE * f;
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char * p;
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f = fopen("/proc/net/route", "r");
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if(!f)
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return -1;
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while(fgets(buf, sizeof(buf), f)) {
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if(line > 0) {
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p = buf;
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while(*p && !isspace(*p))
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p++;
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while(*p && isspace(*p))
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p++;
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if(sscanf(p, "%lx%lx", &d, &g)==2) {
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if(d == 0) { /* default */
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*addr = g;
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fclose(f);
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return 0;
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}
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}
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}
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line++;
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}
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/* not found ! */
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if(f)
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fclose(f);
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return -1;
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}
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#endif
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#ifdef BSD
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#define ROUNDUP(a) \
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((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
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int getdefaultgateway(in_addr_t * addr)
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{
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int mib[] = {CTL_NET, PF_ROUTE, 0, AF_INET,
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NET_RT_DUMP, 0, 0/*tableid*/};
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size_t l;
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char * buf, * p;
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struct rt_msghdr * rt;
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struct sockaddr * sa;
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struct sockaddr * sa_tab[RTAX_MAX];
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int i;
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int r = -1;
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if(sysctl(mib, sizeof(mib)/sizeof(int), 0, &l, 0, 0) < 0) {
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return -1;
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}
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if(l>0) {
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buf = malloc(l);
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if(sysctl(mib, sizeof(mib)/sizeof(int), buf, &l, 0, 0) < 0) {
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return -1;
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}
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for(p=buf; p<buf+l; p+=rt->rtm_msglen) {
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rt = (struct rt_msghdr *)p;
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sa = (struct sockaddr *)(rt + 1);
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for(i=0; i<RTAX_MAX; i++) {
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if(rt->rtm_addrs & (1 << i)) {
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sa_tab[i] = sa;
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sa = (struct sockaddr *)((char *)sa + ROUNDUP(sa->sa_len));
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} else {
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sa_tab[i] = NULL;
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}
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}
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if( ((rt->rtm_addrs & (RTA_DST|RTA_GATEWAY)) == (RTA_DST|RTA_GATEWAY))
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&& sa_tab[RTAX_DST]->sa_family == AF_INET
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&& sa_tab[RTAX_GATEWAY]->sa_family == AF_INET) {
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if(((struct sockaddr_in *)sa_tab[RTAX_DST])->sin_addr.s_addr == 0) {
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*addr = ((struct sockaddr_in *)(sa_tab[RTAX_GATEWAY]))->sin_addr.s_addr;
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r = 0;
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}
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}
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}
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free(buf);
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}
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return r;
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}
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#endif
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