package dhcpd import ( "errors" "fmt" "io/ioutil" "net" "os/exec" "runtime" "strings" "github.com/AdguardTeam/golibs/file" "github.com/AdguardTeam/golibs/log" ) // getValidNetInterfaces returns interfaces that are eligible for DNS and/or DHCP // invalid interface is a ppp interface or the one that doesn't allow broadcasts func getValidNetInterfaces() ([]net.Interface, error) { ifaces, err := net.Interfaces() if err != nil { return nil, fmt.Errorf("Couldn't get list of interfaces: %s", err) } netIfaces := []net.Interface{} for i := range ifaces { if ifaces[i].Flags&net.FlagPointToPoint != 0 { // this interface is ppp, we're not interested in this one continue } iface := ifaces[i] netIfaces = append(netIfaces, iface) } return netIfaces, nil } // Check if network interface has a static IP configured // Supports: Raspbian. func hasStaticIP(ifaceName string) (bool, error) { if runtime.GOOS == "windows" { return false, errors.New("Can't detect static IP: not supported on Windows") } body, err := ioutil.ReadFile("/etc/dhcpcd.conf") if err != nil { return false, err } return hasStaticIPDhcpcdConf(string(body), ifaceName), nil } // for dhcpcd.conf func hasStaticIPDhcpcdConf(data, ifaceName string) bool { lines := strings.Split(data, "\n") nameLine := fmt.Sprintf("interface %s", ifaceName) withinInterfaceCtx := false for _, line := range lines { line = strings.TrimSpace(line) if withinInterfaceCtx && len(line) == 0 { // an empty line resets our state withinInterfaceCtx = false } if len(line) == 0 || line[0] == '#' { continue } line = strings.TrimSpace(line) if !withinInterfaceCtx { if line == nameLine { // we found our interface withinInterfaceCtx = true } } else { if strings.HasPrefix(line, "interface ") { // we found another interface - reset our state withinInterfaceCtx = false continue } if strings.HasPrefix(line, "static ip_address=") { return true } } } return false } // Get IP address with netmask func getFullIP(ifaceName string) string { cmd := exec.Command("ip", "-oneline", "-family", "inet", "address", "show", ifaceName) log.Tracef("executing %s %v", cmd.Path, cmd.Args) d, err := cmd.Output() if err != nil || cmd.ProcessState.ExitCode() != 0 { return "" } fields := strings.Fields(string(d)) if len(fields) < 4 { return "" } _, _, err = net.ParseCIDR(fields[3]) if err != nil { return "" } return fields[3] } // Get gateway IP address func getGatewayIP(ifaceName string) string { cmd := exec.Command("ip", "route", "show", "dev", ifaceName) log.Tracef("executing %s %v", cmd.Path, cmd.Args) d, err := cmd.Output() if err != nil || cmd.ProcessState.ExitCode() != 0 { return "" } fields := strings.Fields(string(d)) if len(fields) < 3 || fields[0] != "default" { return "" } ip := net.ParseIP(fields[2]) if ip == nil { return "" } return fields[2] } // Set a static IP for network interface // Supports: Raspbian. func setStaticIP(ifaceName string) error { ip := getFullIP(ifaceName) if len(ip) == 0 { return errors.New("Can't get IP address") } ip4, _, err := net.ParseCIDR(ip) if err != nil { return err } gatewayIP := getGatewayIP(ifaceName) add := setStaticIPDhcpcdConf(ifaceName, ip, gatewayIP, ip4.String()) body, err := ioutil.ReadFile("/etc/dhcpcd.conf") if err != nil { return err } body = append(body, []byte(add)...) err = file.SafeWrite("/etc/dhcpcd.conf", body) if err != nil { return err } return nil } // for dhcpcd.conf func setStaticIPDhcpcdConf(ifaceName, ip, gatewayIP, dnsIP string) string { var body []byte add := fmt.Sprintf("\ninterface %s\nstatic ip_address=%s\n", ifaceName, ip) body = append(body, []byte(add)...) if len(gatewayIP) != 0 { add = fmt.Sprintf("static routers=%s\n", gatewayIP) body = append(body, []byte(add)...) } add = fmt.Sprintf("static domain_name_servers=%s\n\n", dnsIP) body = append(body, []byte(add)...) return string(body) }