63 lines
1.5 KiB
Go
63 lines
1.5 KiB
Go
package dns
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import (
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"context"
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"io/ioutil"
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"net"
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"strings"
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"github.com/qdm12/gluetun/internal/constants"
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"github.com/qdm12/golibs/os"
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)
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// UseDNSInternally is to change the Go program DNS only.
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func (c *configurator) UseDNSInternally(ip net.IP) {
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c.logger.Info("using DNS address %s internally", ip.String())
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net.DefaultResolver = &net.Resolver{
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PreferGo: true,
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Dial: func(ctx context.Context, network, address string) (net.Conn, error) {
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d := net.Dialer{}
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return d.DialContext(ctx, "udp", net.JoinHostPort(ip.String(), "53"))
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},
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}
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}
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// UseDNSSystemWide changes the nameserver to use for DNS system wide.
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func (c *configurator) UseDNSSystemWide(ip net.IP, keepNameserver bool) error {
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c.logger.Info("using DNS address %s system wide", ip.String())
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const filepath = string(constants.ResolvConf)
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file, err := c.openFile(filepath, os.O_RDWR|os.O_TRUNC, 0644)
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if err != nil {
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return err
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}
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data, err := ioutil.ReadAll(file)
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if err != nil {
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_ = file.Close()
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return err
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}
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s := strings.TrimSuffix(string(data), "\n")
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lines := strings.Split(s, "\n")
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if len(lines) == 1 && lines[0] == "" {
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lines = nil
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}
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found := false
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if !keepNameserver { // default
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for i := range lines {
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if strings.HasPrefix(lines[i], "nameserver ") {
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lines[i] = "nameserver " + ip.String()
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found = true
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}
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}
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}
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if !found {
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lines = append(lines, "nameserver "+ip.String())
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}
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s = strings.Join(lines, "\n") + "\n"
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_, err = file.WriteString(s)
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if err != nil {
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_ = file.Close()
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return err
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}
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return file.Close()
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}
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