/* $Id: getgateway.c,v 1.13 2009/03/10 10:15:31 nanard Exp $ */
/* libnatpmp
* Copyright (c) 2007-2008, 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>
#ifndef WIN32
#include <netinet/in.h>
#endif
#ifndef _MSC_VER
#include <sys/param.h>
#endif
/* There is no portable method to get the default route gateway.
* So below are three differents functions implementing this.
* Parsing /proc/net/route is for linux.
* sysctl is the way to access such informations on BSD systems.
* Many systems should provide route information through raw PF_ROUTE
* sockets. */
#ifdef __linux__
#define USE_PROC_NET_ROUTE
#undef USE_SOCKET_ROUTE
#undef USE_SYSCTL_NET_ROUTE
#endif
#ifdef BSD
#undef USE_PROC_NET_ROUTE
#define USE_SOCKET_ROUTE
#undef USE_SYSCTL_NET_ROUTE
#endif
#ifdef __APPLE__
#undef USE_PROC_NET_ROUTE
#undef USE_SOCKET_ROUTE
#define USE_SYSCTL_NET_ROUTE
#endif
#if ((defined(sun) || defined(__sun)) && defined(__SVR4))
#undef USE_PROC_NET_ROUTE
#define USE_SOCKET_ROUTE
#undef USE_SYSCTL_NET_ROUTE
#endif
#ifdef WIN32
#undef USE_PROC_NET_ROUTE
#undef USE_SOCKET_ROUTE
#undef USE_SYSCTL_NET_ROUTE
#define USE_WIN32_CODE
#endif
#ifdef USE_SYSCTL_NET_ROUTE
#include <stdlib.h>
#include <sys/sysctl.h>
#include <sys/socket.h>
#include <net/route.h>
#endif
#ifdef USE_SOCKET_ROUTE
#include <unistd.h>
#include <string.h>
#include <sys/socket.h>
#include <net/if.h>
#include <net/route.h>
#endif
#ifdef WIN32
#include <unknwn.h>
#include <winreg.h>
#define MAX_KEY_LENGTH 255
#define MAX_VALUE_LENGTH 16383
#endif
#include "getgateway.h"
#ifndef WIN32
#define SUCCESS (0)
#define FAILED (-1)
#endif
#ifdef USE_PROC_NET_ROUTE
int getdefaultgateway(in_addr_t * addr)
{
unsigned long d, g;
char buf[256];
int line = 0;
FILE * f;
char * p;
f = fopen("/proc/net/route", "r");
if(!f)
return FAILED;
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 SUCCESS;
}
}
}
line++;
}
/* default route not found ! */
if(f)
fclose(f);
return FAILED;
}
#endif /* #ifdef USE_PROC_NET_ROUTE */
#ifdef USE_SYSCTL_NET_ROUTE
#define ROUNDUP(a) \
((a) > 0 ? (1 + (((a) - 1) | (sizeof(long) - 1))) : sizeof(long))
int getdefaultgateway(in_addr_t * addr)
{
#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 = FAILED;
if(sysctl(mib, sizeof(mib)/sizeof(int), 0, &l, 0, 0) < 0) {
return FAILED;
}
if(l>0) {
buf = malloc(l);
if(sysctl(mib, sizeof(mib)/sizeof(int), buf, &l, 0, 0) < 0) {
free(buf);
return FAILED;
}
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 = SUCCESS;
}
}
}
free(buf);
}
return r;
}
#endif /* #ifdef USE_SYSCTL_NET_ROUTE */
#ifdef USE_SOCKET_ROUTE
/* Thanks to Darren Kenny for this code */
#define NEXTADDR(w, u) \
if (rtm_addrs & (w)) {\
l = sizeof(struct sockaddr); memmove(cp, &(u), l); cp += l;\
}
#define rtm m_rtmsg.m_rtm
struct {
struct rt_msghdr m_rtm;
char m_space[512];
} m_rtmsg;
int getdefaultgateway(in_addr_t *addr)
{
int s, seq, l, rtm_addrs, i;
pid_t pid;
struct sockaddr so_dst, so_mask;
char *cp = m_rtmsg.m_space;
struct sockaddr *gate = NULL, *sa;
struct rt_msghdr *msg_hdr;
pid = getpid();
seq = 0;
rtm_addrs = RTA_DST | RTA_NETMASK;
memset(&so_dst, 0, sizeof(so_dst));
memset(&so_mask, 0, sizeof(so_mask));
memset(&rtm, 0, sizeof(struct rt_msghdr));
rtm.rtm_type = RTM_GET;
rtm.rtm_flags = RTF_UP | RTF_GATEWAY;
rtm.rtm_version = RTM_VERSION;
rtm.rtm_seq = ++seq;
rtm.rtm_addrs = rtm_addrs;
so_dst.sa_family = AF_INET;
so_mask.sa_family = AF_INET;
NEXTADDR(RTA_DST, so_dst);
NEXTADDR(RTA_NETMASK, so_mask);
rtm.rtm_msglen = l = cp - (char *)&m_rtmsg;
s = socket(PF_ROUTE, SOCK_RAW, 0);
if (write(s, (char *)&m_rtmsg, l) < 0) {
close(s);
return FAILED;
}
do {
l = read(s, (char *)&m_rtmsg, sizeof(m_rtmsg));
} while (l > 0 && (rtm.rtm_seq != seq || rtm.rtm_pid != pid));
close(s);
msg_hdr = &rtm;
cp = ((char *)(msg_hdr + 1));
if (msg_hdr->rtm_addrs) {
for (i = 1; i; i <<= 1)
if (i & msg_hdr->rtm_addrs) {
sa = (struct sockaddr *)cp;
if (i == RTA_GATEWAY )
gate = sa;
cp += sizeof(struct sockaddr);
}
} else {
return FAILED;
}
if (gate != NULL ) {
*addr = ((struct sockaddr_in *)gate)->sin_addr.s_addr;
return SUCCESS;
} else {
return FAILED;
}
}
#endif /* #ifdef USE_SOCKET_ROUTE */
#ifdef USE_WIN32_CODE
int getdefaultgateway(in_addr_t * addr)
{
HKEY networkCardsKey;
HKEY networkCardKey;
HKEY interfacesKey;
HKEY interfaceKey;
DWORD i = 0;
DWORD numSubKeys = 0;
TCHAR keyName[MAX_KEY_LENGTH];
DWORD keyNameLength = MAX_KEY_LENGTH;
BYTE keyValue[MAX_VALUE_LENGTH];
DWORD keyValueLength = MAX_VALUE_LENGTH;
DWORD keyValueType = REG_SZ;
BYTE gatewayValue[MAX_VALUE_LENGTH];
DWORD gatewayValueLength = MAX_VALUE_LENGTH;
DWORD gatewayValueType = REG_MULTI_SZ;
int done = 0;
char networkCardsPath[] = "SOFTWARE\\Microsoft\\Windows NT\\CurrentVersion\\NetworkCards";
char interfacesPath[] = "SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters\\Interfaces";
// The windows registry lists its primary network devices in the following location:
// HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\NetworkCards
//
// Each network device has its own subfolder, named with an index, with various properties:
// -NetworkCards
// -5
// -Description = Broadcom 802.11n Network Adapter
// -ServiceName = {E35A72F8-5065-4097-8DFE-C7790774EE4D}
// -8
// -Description = Marvell Yukon 88E8058 PCI-E Gigabit Ethernet Controller
// -ServiceName = {86226414-5545-4335-A9D1-5BD7120119AD}
//
// The above service name is the name of a subfolder within:
// HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\Tcpip\Parameters\Interfaces
//
// There may be more subfolders in this interfaces path than listed in the network cards path above:
// -Interfaces
// -{3a539854-6a70-11db-887c-806e6f6e6963}
// -DhcpIPAddress = 0.0.0.0
// -[more]
// -{E35A72F8-5065-4097-8DFE-C7790774EE4D}
// -DhcpIPAddress = 10.0.1.4
// -DhcpDefaultGateway = 10.0.1.1
// -[more]
// -{86226414-5545-4335-A9D1-5BD7120119AD}
// -DhcpIpAddress = 10.0.1.5
// -DhcpDefaultGateay = 10.0.1.1
// -[more]
//
// In order to extract this information, we enumerate each network card, and extract the ServiceName value.
// This is then used to open the interface subfolder, and attempt to extract a DhcpDefaultGateway value.
// Once one is found, we're done.
//
// It may be possible to simply enumerate the interface folders until we find one with a DhcpDefaultGateway value.
// However, the technique used is the technique most cited on the web, and we assume it to be more correct.
if(ERROR_SUCCESS != RegOpenKeyEx(HKEY_LOCAL_MACHINE, // Open registry key or predifined key
networkCardsPath, // Name of registry subkey to open
0, // Reserved - must be zero
KEY_READ, // Mask - desired access rights
&networkCardsKey)) // Pointer to output key
{
// Unable to open network cards keys
return -1;
}
if(ERROR_SUCCESS != RegOpenKeyEx(HKEY_LOCAL_MACHINE, // Open registry key or predefined key
interfacesPath, // Name of registry subkey to open
0, // Reserved - must be zero
KEY_READ, // Mask - desired access rights
&interfacesKey)) // Pointer to output key
{
// Unable to open interfaces key
RegCloseKey(networkCardsKey);
return -1;
}
// Figure out how many subfolders are within the NetworkCards folder
RegQueryInfoKey(networkCardsKey, NULL, NULL, NULL, &numSubKeys, NULL, NULL, NULL, NULL, NULL, NULL, NULL);
//printf( "Number of subkeys: %u\n", (unsigned int)numSubKeys);
// Enumrate through each subfolder within the NetworkCards folder
for(i = 0; i < numSubKeys && !done; i++)
{
keyNameLength = MAX_KEY_LENGTH;
if(ERROR_SUCCESS == RegEnumKeyEx(networkCardsKey, // Open registry key
i, // Index of subkey to retrieve
keyName, // Buffer that receives the name of the subkey
&keyNameLength, // Variable that receives the size of the above buffer
NULL, // Reserved - must be NULL
NULL, // Buffer that receives the class string
NULL, // Variable that receives the size of the above buffer
NULL)) // Variable that receives the last write time of subkey
{
if(RegOpenKeyEx(networkCardsKey, keyName, 0, KEY_READ, &networkCardKey) == ERROR_SUCCESS)
{
keyValueLength = MAX_VALUE_LENGTH;
if(ERROR_SUCCESS == RegQueryValueEx(networkCardKey, // Open registry key
"ServiceName", // Name of key to query
NULL, // Reserved - must be NULL
&keyValueType, // Receives value type
keyValue, // Receives value
&keyValueLength)) // Receives value length in bytes
{
//printf("keyValue: %s\n", keyValue);
if(RegOpenKeyEx(interfacesKey, (char *)keyValue, 0, KEY_READ, &interfaceKey) == ERROR_SUCCESS)
{
gatewayValueLength = MAX_VALUE_LENGTH;
if(ERROR_SUCCESS == RegQueryValueEx(interfaceKey, // Open registry key
"DhcpDefaultGateway", // Name of key to query
NULL, // Reserved - must be NULL
&gatewayValueType, // Receives value type
gatewayValue, // Receives value
&gatewayValueLength)) // Receives value length in bytes
{
// Check to make sure it's a string
if(gatewayValueType == REG_MULTI_SZ || gatewayValueType == REG_SZ)
{
//printf("gatewayValue: %s\n", gatewayValue);
done = 1;
}
}
else if(ERROR_SUCCESS == RegQueryValueEx(interfaceKey, // Open registry key
"DefaultGateway", // Name of key to query
NULL, // Reserved - must be NULL
&gatewayValueType, // Receives value type
gatewayValue, // Receives value
&gatewayValueLength)) // Receives value length in bytes
{
// Check to make sure it's a string
if(gatewayValueType == REG_MULTI_SZ || gatewayValueType == REG_SZ)
{
//printf("gatewayValue: %s\n", gatewayValue);
done = 1;
}
}
RegCloseKey(interfaceKey);
}
}
RegCloseKey(networkCardKey);
}
}
}
RegCloseKey(interfacesKey);
RegCloseKey(networkCardsKey);
if(done)
{
*addr = inet_addr((char *)gatewayValue);
return 0;
}
return -1;
}
#endif /* #ifdef USE_WIN32_CODE */