mirror of
https://github.com/gravitl/netmaker.git
synced 2024-09-22 00:06:04 +08:00
127 lines
3.2 KiB
Go
127 lines
3.2 KiB
Go
package local
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import (
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"fmt"
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"net"
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"os"
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"strings"
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"time"
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//"github.com/davecgh/go-spew/spew"
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"log"
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"os/exec"
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"github.com/gravitl/netmaker/netclient/ncutils"
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)
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const DNS_UNREACHABLE_ERROR = "nameserver unreachable"
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func SetDNSWithRetry(iface, network, address string) {
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var reachable bool
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for counter := 0; !reachable && counter < 5; counter++ {
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reachable = IsDNSReachable(address)
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time.Sleep(time.Second << 1)
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}
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if !reachable {
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ncutils.Log("not setting dns, server unreachable: " + address)
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} else if err := UpdateDNS(iface, network, address); err != nil {
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ncutils.Log("error applying dns" + err.Error())
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}
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}
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// SetDNS - sets the DNS of a local machine
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func SetDNS(nameserver string) error {
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bytes, err := os.ReadFile("/etc/resolv.conf")
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if err != nil {
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return err
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}
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resolvstring := string(bytes)
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// //check whether s contains substring text
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hasdns := strings.Contains(resolvstring, nameserver)
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if hasdns {
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return nil
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}
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resolv, err := os.OpenFile("/etc/resolv.conf", os.O_APPEND|os.O_WRONLY, 0644)
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if err != nil {
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return err
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}
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defer resolv.Close()
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_, err = resolv.WriteString("nameserver " + nameserver + "\n")
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return err
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}
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// UpdateDNS - updates local DNS of client
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func UpdateDNS(ifacename string, network string, nameserver string) error {
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if ifacename == "" {
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return fmt.Errorf("cannot set dns: interface name is blank")
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}
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if network == "" {
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return fmt.Errorf("cannot set dns: network name is blank")
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}
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if nameserver == "" {
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return fmt.Errorf("cannot set dns: nameserver is blank")
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}
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if ncutils.IsWindows() {
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return nil
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}
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if !IsDNSReachable(nameserver) {
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return fmt.Errorf(DNS_UNREACHABLE_ERROR + " : " + nameserver + ":53")
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}
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_, err := exec.LookPath("resolvectl")
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if err != nil {
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log.Println(err)
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log.Println("WARNING: resolvectl not present. Unable to set dns. Install resolvectl or run manually.")
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} else {
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_, err = ncutils.RunCmd("resolvectl domain "+ifacename+" ~"+network, true)
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if err != nil {
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log.Println("WARNING: Error encountered setting domain on dns. Aborted setting dns.")
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} else {
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_, err = ncutils.RunCmd("resolvectl default-route "+ifacename+" false", true)
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if err != nil {
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log.Println("WARNING: Error encountered setting default-route on dns. Aborted setting dns.")
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} else {
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_, err = ncutils.RunCmd("resolvectl dns "+ifacename+" "+nameserver, true)
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if err != nil {
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log.Println("WARNING: Error encountered running resolvectl dns " + ifacename + " " + nameserver)
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}
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}
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}
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}
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return err
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}
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// IsDNSReachable - checks if nameserver is reachable
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func IsDNSReachable(nameserver string) bool {
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port := "53"
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protocols := [2]string{"tcp", "udp"}
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for _, proto := range protocols {
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timeout := time.Second
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conn, err := net.DialTimeout(proto, net.JoinHostPort(nameserver, port), timeout)
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if err != nil {
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return false
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}
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if conn != nil {
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defer conn.Close()
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} else {
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return false
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}
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}
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return true
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}
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// IsDNSWorking - checks if record is returned by correct nameserver
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func IsDNSWorking(network string, nameserver string) bool {
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var isworking bool
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servers, err := net.LookupNS("netmaker" + "." + "network")
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if err != nil {
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return isworking
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}
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for _, ns := range servers {
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if strings.Contains(ns.Host, nameserver) {
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isworking = true
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}
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}
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return isworking
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}
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