2020-12-12 07:46:54 +01:00
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package resolvers
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2020-12-15 18:39:10 +01:00
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import (
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"errors"
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"fmt"
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"net"
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"runtime"
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"github.com/miekg/dns"
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)
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2020-12-12 07:46:54 +01:00
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// prepareMessages takes a slice fo `dns.Question`
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// and initialises `dns.Messages` for each question
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func prepareMessages(questions []dns.Question) []dns.Msg {
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var messages = make([]dns.Msg, 0, len(questions))
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for _, q := range questions {
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msg := dns.Msg{}
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msg.Id = dns.Id()
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msg.RecursionDesired = true
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// It's recommended to only send 1 question for 1 DNS message.
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msg.Question = []dns.Question{q}
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messages = append(messages, msg)
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}
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return messages
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}
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2020-12-15 18:39:10 +01:00
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func getDefaultServers() ([]string, error) {
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if runtime.GOOS == "windows" {
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// TODO: Add a method for reading system default nameserver in windows.
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return nil, errors.New(`unable to read default nameservers in this machine`)
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}
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// if no nameserver is provided, take it from `resolv.conf`
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cfg, err := dns.ClientConfigFromFile(DefaultResolvConfPath)
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if err != nil {
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return nil, err
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}
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servers := make([]string, 0, len(cfg.Servers))
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for _, s := range cfg.Servers {
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ip := net.ParseIP(s)
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// handle IPv6
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if ip != nil && ip.To4() != nil {
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servers = append(servers, fmt.Sprintf("%s:%s", s, cfg.Port))
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} else {
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servers = append(servers, fmt.Sprintf("[%s]:%s", s, cfg.Port))
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}
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}
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return servers, nil
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}
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