mirror of
https://github.com/tailscale/tailscale.git
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57 lines
1.1 KiB
Go
57 lines
1.1 KiB
Go
// Copyright (c) 2021 Tailscale Inc & AUTHORS All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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//go:build ignore
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// +build ignore
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// Command dns_tester exists in order to perform tests of our DNS
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// configuration stack. This was written because the state of DNS
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// in our target environments is so diverse that we need a little tool
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// to do this test for us.
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package main
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import (
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"context"
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"encoding/json"
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"flag"
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"net"
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"os"
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"time"
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)
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func main() {
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flag.Parse()
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target := flag.Arg(0)
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ctx, cancel := context.WithCancel(context.Background())
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defer cancel()
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errCount := 0
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wait := 25 * time.Millisecond
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for range make([]struct{}, 5) {
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err := lookup(ctx, target)
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if err != nil {
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errCount++
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time.Sleep(wait)
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wait = wait * 2
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continue
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}
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break
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}
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}
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func lookup(ctx context.Context, target string) error {
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ctx, cancel := context.WithTimeout(ctx, time.Second)
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defer cancel()
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hosts, err := net.LookupHost(target)
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if err != nil {
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return err
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}
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json.NewEncoder(os.Stdout).Encode(hosts)
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return nil
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}
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