source: trunk/third-party/libnatpmp/getgateway.c @ 4095

/* $Id: getgateway.c,v 1.4 2007/11/22 18:01:37 nanard Exp $ */
/* libnatpmp
 * Copyright (c) 2007, Thomas BERNARD <miniupnp@free.fr>
 *
 * Permission to use, copy, modify, and/or distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
#include <stdio.h>
#include <ctype.h>
#include <netinet/in.h>
#include <sys/param.h>
#ifdef BSD
#include <stdlib.h>
#include <sys/sysctl.h>
#include <sys/socket.h>
#include <net/route.h>
#endif
#include "getgateway.h"

#ifdef __linux__
int getdefaultgateway(in_addr_t * addr)
{
        long d, g;
        char buf[256];
        int line = 0;
        FILE * f;
        char * p;
        f = fopen("/proc/net/route", "r");
        if(!f)
                return -1;
        while(fgets(buf, sizeof(buf), f)) {
                if(line > 0) {
                        p = buf;
                        while(*p && !isspace(*p))
                                p++;
                        while(*p && isspace(*p))
                                p++;
                        if(sscanf(p, "%lx%lx", &d, &g)==2) {
                                if(d == 0) { /* default */
                                        *addr = g;
                                        fclose(f);
                                        return 0;
                                }
                        }
                }
                line++;
        }
        /* not found ! */
        if(f)
                fclose(f);
        return -1;
}
#endif

#ifdef BSD 

#define ROUNDUP(a) \
        ((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))

int getdefaultgateway(in_addr_t * addr)
{
        int mib[] = {CTL_NET, PF_ROUTE, 0, AF_INET,
                     NET_RT_DUMP, 0, 0/*tableid*/};
        size_t l;
        char * buf, * p;
        struct rt_msghdr * rt;
        struct sockaddr * sa;
        struct sockaddr * sa_tab[RTAX_MAX];
        int i;
        int r = -1;
        if(sysctl(mib, sizeof(mib)/sizeof(int), 0, &l, 0, 0) < 0) {
                return -1;
        }
        if(l>0) {
                buf = malloc(l);
                if(sysctl(mib, sizeof(mib)/sizeof(int), buf, &l, 0, 0) < 0) {
                        return -1;
                }
                for(p=buf; p<buf+l; p+=rt->rtm_msglen) {
                        rt = (struct rt_msghdr *)p;
                        sa = (struct sockaddr *)(rt + 1);
                        for(i=0; i<RTAX_MAX; i++) {
                                if(rt->rtm_addrs & (1 << i)) {
                                        sa_tab[i] = sa;
                                        sa = (struct sockaddr *)((char *)sa + ROUNDUP(sa->sa_len));
                                } else {
                                        sa_tab[i] = NULL;
                                }
                        }
                        if( ((rt->rtm_addrs & (RTA_DST|RTA_GATEWAY)) == (RTA_DST|RTA_GATEWAY))
              && sa_tab[RTAX_DST]->sa_family == AF_INET
              && sa_tab[RTAX_GATEWAY]->sa_family == AF_INET) {
                                if(((struct sockaddr_in *)sa_tab[RTAX_DST])->sin_addr.s_addr == 0) {
                                        *addr = ((struct sockaddr_in *)(sa_tab[RTAX_GATEWAY]))->sin_addr.s_addr;
                                        r = 0;
                                }
                        }
                }
                free(buf);
        }
        return r;
}
#endif