package addr import ( "fmt" "net" ) var ( privateBlocks []*net.IPNet ) func init() { for _, b := range []string{"10.0.0.0/8", "172.16.0.0/12", "192.168.0.0/16", "100.64.0.0/10", "fd00::/8"} { if _, block, err := net.ParseCIDR(b); err == nil { privateBlocks = append(privateBlocks, block) } } } func isPrivateIP(ipAddr string) bool { ip := net.ParseIP(ipAddr) for _, priv := range privateBlocks { if priv.Contains(ip) { return true } } return false } // Extract returns a real ip func Extract(addr string) (string, error) { // if addr specified then its returned if len(addr) > 0 && (addr != "0.0.0.0" && addr != "[::]" && addr != "::") { return addr, nil } ifaces, err := net.Interfaces() if err != nil { return "", fmt.Errorf("Failed to get interfaces! Err: %v", err) } var addrs []net.Addr var loAddrs []net.Addr for _, iface := range ifaces { ifaceAddrs, err := iface.Addrs() if err != nil { // ignore error, interface can dissapear from system continue } if iface.Flags&net.FlagLoopback != 0 { loAddrs = append(loAddrs, ifaceAddrs...) continue } addrs = append(addrs, ifaceAddrs...) } addrs = append(addrs, loAddrs...) var ipAddr []byte var publicIP []byte for _, rawAddr := range addrs { var ip net.IP switch addr := rawAddr.(type) { case *net.IPAddr: ip = addr.IP case *net.IPNet: ip = addr.IP default: continue } if !isPrivateIP(ip.String()) { publicIP = ip continue } ipAddr = ip break } // return private ip if ipAddr != nil { return net.IP(ipAddr).String(), nil } // return public or virtual ip if publicIP != nil { return net.IP(publicIP).String(), nil } return "", fmt.Errorf("No IP address found, and explicit IP not provided") } // IPs returns all known ips func IPs() []string { ifaces, err := net.Interfaces() if err != nil { return nil } var ipAddrs []string for _, i := range ifaces { addrs, err := i.Addrs() if err != nil { continue } for _, addr := range addrs { var ip net.IP switch v := addr.(type) { case *net.IPNet: ip = v.IP case *net.IPAddr: ip = v.IP } if ip == nil { continue } // dont skip ipv6 addrs /* ip = ip.To4() if ip == nil { continue } */ ipAddrs = append(ipAddrs, ip.String()) } } return ipAddrs }