transmission/third-party/libnatpmp/getgateway.c

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/* $Id: getgateway.c,v 1.6 2007/12/13 14:46:06 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. */
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#include <stdio.h>
#include <ctype.h>
#include <netinet/in.h>
#include <sys/param.h>
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#if defined(BSD) || defined(__APPLE__)
#include <stdlib.h>
#include <sys/sysctl.h>
#include <sys/socket.h>
#include <net/route.h>
#endif
#include "getgateway.h"
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#ifdef __linux__
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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;
}
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#endif
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#if defined(BSD) || defined(__APPLE__)
#define ROUNDUP(a) \
((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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#if 0
/* net.route.0.inet.dump.0.0 ? */
int mib[] = {CTL_NET, PF_ROUTE, 0, AF_INET,
NET_RT_DUMP, 0, 0/*tableid*/};
#endif
/* net.route.0.inet.flags.gateway */
int mib[] = {CTL_NET, PF_ROUTE, 0, AF_INET,
NET_RT_FLAGS, RTF_GATEWAY};
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;
}
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#endif