alibaba/kt-connect

package dns

import (
    "fmt"
    "github.com/alibaba/kt-connect/pkg/common"
    "github.com/alibaba/kt-connect/pkg/kt/util"
    "github.com/rs/zerolog/log"
    "os/exec"
    "regexp"
    "strings"
)

// SetNameServer set dns server records
func SetNameServer(dnsServer string) (err error) {
    // run command: netsh interface ip set interface KtConnectTunnel metric=2
    if _, _, err = util.RunAndWait(exec.Command("netsh",
        "interface",
        "ipv4",
        "set",
        "interface",
        util.TunNameWin,
        "metric=2",
    )); err != nil {
        log.Error().Msgf("Failed to set tun device order")
        return err
    }
    // run command: netsh interface ip set dnsservers name=KtConnectTunnel source=static address=8.8.8.8
    if _, _, err = util.RunAndWait(exec.Command("netsh",
        "interface",
        "ipv4",
        "set",
        "dnsservers",
        fmt.Sprintf("name=%s", util.TunNameWin),
        "source=static",
        fmt.Sprintf("address=%s", strings.Split(dnsServer, ":")[0]),
    )); err != nil {
        log.Error().Msgf("Failed to set dns server of tun device")
        return err
    }
    return nil
}

// HandleExtraDomainMapping handle extra domain change
func HandleExtraDomainMapping(extraDomains map[string]string, localDnsPort int) {
    // pass
}

// RestoreNameServer ...
func RestoreNameServer() {
    // Windows dns config is set on device, so explicit removal is unnecessary
}

// GetLocalDomains ...
func GetLocalDomains() string {
    return ""
}

// GetNameServer get dns server of the default interface
func GetNameServer() string {
    // run command: netsh interface ip show dnsservers
    out, _, err := util.RunAndWait(exec.Command("netsh",
        "interface",
        "ipv4",
        "show",
        "dnsservers",
    ))
    if err != nil {
        log.Error().Msgf("Failed to get upstream dns server")
        return ""
    }
    _, _ = util.BackgroundLogger.Write([]byte(">> Get dns: " + out + util.Eol))

    r, _ := regexp.Compile(util.IpAddrPattern)
    nsAddresses := r.FindAllString(out, 10)
    if nsAddresses == nil {
        log.Warn().Msgf("No upstream dns server available")
        return ""
    }
    for _, addr := range nsAddresses {
        if addr != common.Localhost {
            return addr
        }
    }
    log.Warn().Msgf("No valid upstream dns server available")
    return ""
}