/* $Id: getifaddr.c,v 1.28 2022/02/19 18:58:25 nanard Exp $ */ /* vim: tabstop=4 shiftwidth=4 noexpandtab * MiniUPnP project * http://miniupnp.free.fr/ or https://miniupnp.tuxfamily.org/ * (c) 2006-2024 Thomas Bernard * This software is subject to the conditions detailed * in the LICENCE file provided within the distribution */ #include #include #include #include #include #include #include #include #include #include #if defined(sun) #include #endif #include "config.h" #include "getifaddr.h" #if defined(USE_GETIFADDRS) || defined(ENABLE_IPV6) || defined(ENABLE_PCP) #include #endif int getifaddr(const char * ifname, char * buf, int len, struct in_addr * addr, struct in_addr * mask) { #ifndef USE_GETIFADDRS /* use ioctl SIOCGIFADDR. Works only for ip v4 */ /* SIOCGIFADDR struct ifreq * */ int s; struct ifreq ifr; int ifrlen; struct sockaddr_in * ifaddr; ifrlen = sizeof(ifr); if(!ifname || ifname[0]=='\0') return -1; s = socket(PF_INET, SOCK_DGRAM, 0); if(s < 0) { syslog(LOG_ERR, "socket(PF_INET, SOCK_DGRAM): %m"); return -1; } strncpy(ifr.ifr_name, ifname, IFNAMSIZ-1); ifr.ifr_name[IFNAMSIZ-1] = '\0'; if(ioctl(s, SIOCGIFFLAGS, &ifr, &ifrlen) < 0) { syslog(LOG_DEBUG, "ioctl(s, SIOCGIFFLAGS, ...): %m"); close(s); return -1; } if ((ifr.ifr_flags & IFF_UP) == 0) { syslog(LOG_DEBUG, "network interface %s is down", ifname); close(s); return -1; } strncpy(ifr.ifr_name, ifname, IFNAMSIZ-1); ifr.ifr_name[IFNAMSIZ-1] = '\0'; if(ioctl(s, SIOCGIFADDR, &ifr, &ifrlen) < 0) { syslog(LOG_ERR, "ioctl(s, SIOCGIFADDR, ...): %m"); close(s); return -1; } ifaddr = (struct sockaddr_in *)&ifr.ifr_addr; if(addr) *addr = ifaddr->sin_addr; if(buf) { if(!inet_ntop(AF_INET, &ifaddr->sin_addr, buf, len)) { syslog(LOG_ERR, "inet_ntop(): %m"); close(s); return -1; } } if(mask) { strncpy(ifr.ifr_name, ifname, IFNAMSIZ-1); ifr.ifr_name[IFNAMSIZ-1] = '\0'; if(ioctl(s, SIOCGIFNETMASK, &ifr, &ifrlen) < 0) { syslog(LOG_ERR, "ioctl(s, SIOCGIFNETMASK, ...): %m"); close(s); return -1; } #ifdef ifr_netmask *mask = ((struct sockaddr_in *)&ifr.ifr_netmask)->sin_addr; #else *mask = ((struct sockaddr_in *)&ifr.ifr_addr)->sin_addr; #endif } close(s); #else /* ifndef USE_GETIFADDRS */ /* Works for all address families (both ip v4 and ip v6) */ struct ifaddrs * ifap; struct ifaddrs * ife; struct ifaddrs * candidate = NULL; if(!ifname || ifname[0]=='\0') return -1; if(getifaddrs(&ifap)<0) { syslog(LOG_ERR, "getifaddrs: %m"); return -1; } for(ife = ifap; ife; ife = ife->ifa_next) { /* skip other interfaces if one was specified */ if(ifname && (0 != strcmp(ifname, ife->ifa_name))) continue; if(ife->ifa_addr == NULL) continue; switch(ife->ifa_addr->sa_family) { case AF_INET: /* only consider the address if it is the 1st candidate or if it is not privante AND the current candidate is a private address. So we return a private address only if there is no public address on this interface */ if(!candidate || (addr_is_reserved(&((struct sockaddr_in *)candidate->ifa_addr)->sin_addr) && !addr_is_reserved(&((struct sockaddr_in *)ife->ifa_addr)->sin_addr))) candidate = ife; break; /* case AF_INET6: inet_ntop(ife->ifa_addr->sa_family, &((struct sockaddr_in6 *)ife->ifa_addr)->sin6_addr, buf, len); */ } } if(candidate) { if(buf) { inet_ntop(candidate->ifa_addr->sa_family, &((struct sockaddr_in *)candidate->ifa_addr)->sin_addr, buf, len); } if(addr) *addr = ((struct sockaddr_in *)candidate->ifa_addr)->sin_addr; if(mask) *mask = ((struct sockaddr_in *)candidate->ifa_netmask)->sin_addr; } else { syslog(LOG_WARNING, "no AF_INET address found for %s", ifname); freeifaddrs(ifap); return -1; } freeifaddrs(ifap); #endif return 0; } #ifdef ENABLE_PCP int getifaddr_in6(const char * ifname, int af, struct in6_addr * addr) { #if defined(ENABLE_IPV6) || defined(USE_GETIFADDRS) struct ifaddrs * ifap; struct ifaddrs * ife; #ifdef ENABLE_IPV6 const struct sockaddr_in6 * tmpaddr; #endif /* ENABLE_IPV6 */ int found = 0; if(!ifname || ifname[0]=='\0') return -1; if(getifaddrs(&ifap)<0) { syslog(LOG_ERR, "getifaddrs: %m"); return -1; } for(ife = ifap; ife && !found; ife = ife->ifa_next) { /* skip other interfaces if one was specified */ if(ifname && (0 != strcmp(ifname, ife->ifa_name))) continue; if(ife->ifa_addr == NULL) continue; if (ife->ifa_addr->sa_family != af) continue; switch(ife->ifa_addr->sa_family) { case AF_INET: /* IPv4-mapped IPv6 address ::ffff:1.2.3.4 */ memset(addr->s6_addr, 0, 10); addr->s6_addr[10] = 0xff; addr->s6_addr[11] = 0xff; memcpy(addr->s6_addr + 12, &(((struct sockaddr_in *)ife->ifa_addr)->sin_addr.s_addr), 4); found = 1; break; #ifdef ENABLE_IPV6 case AF_INET6: tmpaddr = (const struct sockaddr_in6 *)ife->ifa_addr; if(!IN6_IS_ADDR_LOOPBACK(&tmpaddr->sin6_addr) && !IN6_IS_ADDR_LINKLOCAL(&tmpaddr->sin6_addr)) { memcpy(addr->s6_addr, &tmpaddr->sin6_addr, 16); found = 1; } break; #endif /* ENABLE_IPV6 */ } } freeifaddrs(ifap); return (found ? 0 : -1); #else /* defined(ENABLE_IPV6) || defined(USE_GETIFADDRS) */ /* IPv4 only */ struct in_addr addr4; if(af != AF_INET) return -1; if(getifaddr(ifname, NULL, 0, &addr4, NULL) < 0) return -1; /* IPv4-mapped IPv6 address ::ffff:1.2.3.4 */ memset(addr->s6_addr, 0, 10); addr->s6_addr[10] = 0xff; addr->s6_addr[11] = 0xff; memcpy(addr->s6_addr + 12, &addr4.s_addr, 4); return 0; #endif } #endif /* ENABLE_PCP */ #ifdef ENABLE_IPV6 int find_ipv6_addr(const char * ifname, char * dst, int n) { struct ifaddrs * ifap; struct ifaddrs * ife; const struct sockaddr_in6 * addr; char buf[64]; int r = 0; if(!dst) return -1; if(getifaddrs(&ifap)<0) { syslog(LOG_ERR, "getifaddrs: %m"); return -1; } for(ife = ifap; ife; ife = ife->ifa_next) { /* skip other interfaces if one was specified */ if(ifname && (0 != strcmp(ifname, ife->ifa_name))) continue; if(ife->ifa_addr == NULL) continue; if(ife->ifa_addr->sa_family == AF_INET6) { addr = (const struct sockaddr_in6 *)ife->ifa_addr; if(!IN6_IS_ADDR_LOOPBACK(&addr->sin6_addr) && !IN6_IS_ADDR_LINKLOCAL(&addr->sin6_addr) /* RFC4193 "Unique Local IPv6 Unicast Addresses" only if no * other address found */ && (r == 0 || (addr->sin6_addr.s6_addr[0] & 0xfe) != 0xfc)) { inet_ntop(ife->ifa_addr->sa_family, &addr->sin6_addr, buf, sizeof(buf)); /* add brackets */ snprintf(dst, n, "[%s]", buf); r = 1; } } } freeifaddrs(ifap); return r; } #endif /* List of IP address blocks which are private / reserved and therefore not suitable for public external IP addresses */ /* If interface has IP address from one of this block, then it is either behind NAT or port forwarding is impossible */ #define IP(a, b, c, d) (((a) << 24) + ((b) << 16) + ((c) << 8) + (d)) #define MSK(m) (32-(m)) static const struct { uint32_t address; uint32_t rmask; } reserved[] = { { IP( 0, 0, 0, 0), MSK( 8) }, /* RFC1122 "This host on this network" */ { IP( 10, 0, 0, 0), MSK( 8) }, /* RFC1918 Private-Use */ { IP(100, 64, 0, 0), MSK(10) }, /* RFC6598 Shared Address Space */ { IP(127, 0, 0, 0), MSK( 8) }, /* RFC1122 Loopback */ { IP(169, 254, 0, 0), MSK(16) }, /* RFC3927 Link-Local */ { IP(172, 16, 0, 0), MSK(12) }, /* RFC1918 Private-Use */ { IP(192, 0, 0, 0), MSK(24) }, /* RFC6890 IETF Protocol Assignments */ { IP(192, 0, 2, 0), MSK(24) }, /* RFC5737 Documentation (TEST-NET-1) */ { IP(192, 31, 196, 0), MSK(24) }, /* RFC7535 AS112-v4 */ { IP(192, 52, 193, 0), MSK(24) }, /* RFC7450 AMT */ { IP(192, 88, 99, 0), MSK(24) }, /* RFC7526 6to4 Relay Anycast */ { IP(192, 168, 0, 0), MSK(16) }, /* RFC1918 Private-Use */ { IP(192, 175, 48, 0), MSK(24) }, /* RFC7534 Direct Delegation AS112 Service */ { IP(198, 18, 0, 0), MSK(15) }, /* RFC2544 Benchmarking */ { IP(198, 51, 100, 0), MSK(24) }, /* RFC5737 Documentation (TEST-NET-2) */ { IP(203, 0, 113, 0), MSK(24) }, /* RFC5737 Documentation (TEST-NET-3) */ { IP(224, 0, 0, 0), MSK( 4) }, /* RFC1112 Multicast */ { IP(240, 0, 0, 0), MSK( 4) }, /* RFC1112 Reserved for Future Use + RFC919 Limited Broadcast */ }; #undef IP #undef MSK int addr_is_reserved(struct in_addr * addr) { uint32_t address = ntohl(addr->s_addr); size_t i; for (i = 0; i < sizeof(reserved)/sizeof(reserved[0]); ++i) { if ((address >> reserved[i].rmask) == (reserved[i].address >> reserved[i].rmask)) return 1; } return 0; }