tailscale/net/dns/manager_openbsd.go

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// Copyright (c) 2020 Tailscale Inc & AUTHORS All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package dns
import (
"bytes"
"fmt"
"os"
"tailscale.com/types/logger"
)
type kv struct {
k, v string
}
func (kv kv) String() string {
return fmt.Sprintf("%s=%s", kv.k, kv.v)
}
func NewOSConfigurator(logf logger.Logf, interfaceName string) (OSConfigurator, error) {
return newOSConfigurator(logf, interfaceName,
newOSConfigEnv{
rcIsResolvd: rcIsResolvd,
fs: directFS{},
})
}
// newOSConfigEnv are the funcs newOSConfigurator needs, pulled out for testing.
type newOSConfigEnv struct {
fs directFS
rcIsResolvd func(resolvConfContents []byte) bool
}
func newOSConfigurator(logf logger.Logf, interfaceName string, env newOSConfigEnv) (ret OSConfigurator, err error) {
var debug []kv
dbg := func(k, v string) {
debug = append(debug, kv{k, v})
}
defer func() {
if ret != nil {
dbg("ret", fmt.Sprintf("%T", ret))
}
logf("dns: %v", debug)
}()
bs, err := env.fs.ReadFile(resolvConf)
if os.IsNotExist(err) {
dbg("rc", "missing")
return newDirectManager(logf), nil
}
if err != nil {
return nil, fmt.Errorf("reading /etc/resolv.conf: %w", err)
}
if env.rcIsResolvd(bs) {
dbg("resolvd", "yes")
return newResolvdManager(logf, interfaceName)
}
dbg("resolvd", "missing")
return newDirectManager(logf), nil
}
func rcIsResolvd(resolvConfContents []byte) bool {
// If we have the string "# resolvd:" in resolv.conf resolvd(8) is
// managing things.
if bytes.Contains(resolvConfContents, []byte("# resolvd:")) {
return true
}
return false
}