/* $Id: getgateway.c,v 1.12 2008/10/06 10:04:16 nanard Exp $ */ /* libnatpmp * Copyright (c) 2007-2008, Thomas BERNARD * * 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 #include #ifndef WIN32 #include #endif #include /* 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(__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 #include #include #include #endif #ifdef USE_SOCKET_ROUTE #include #include #include #include #include #endif #ifdef WIN32 #include #include #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) { 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; prtm_msglen) { rt = (struct rt_msghdr *)p; sa = (struct sockaddr *)(rt + 1); for(i=0; irtm_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; TCHAR keyValue[MAX_VALUE_LENGTH]; DWORD keyValueLength = MAX_VALUE_LENGTH; DWORD keyValueType = REG_SZ; TCHAR 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, 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; } } RegCloseKey(interfaceKey); } } RegCloseKey(networkCardKey); } } } RegCloseKey(interfacesKey); RegCloseKey(networkCardsKey); if(done) { *addr = inet_addr(gatewayValue); return 0; } return -1; } #endif /* #ifdef USE_WIN32_CODE */