63 lines
1.5 KiB
Go
63 lines
1.5 KiB
Go
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// dns utils
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package utils
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import (
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"github.com/miekg/dns"
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)
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type DNSOptions struct {
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Domain string
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RD bool
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Qclass uint16
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Qtype uint16
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EDNS bool
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}
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// build the question section of a dns packet
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func questionMaker(domain string, qclass uint16, qtype uint16) *dns.Question {
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return &dns.Question{Name: dns.Fqdn(domain), Qtype: qtype, Qclass: qclass}
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}
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// build a specific query message
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func queryMaker(domain string, rd bool, qclass uint16, qtype uint16, edns bool) *dns.Msg {
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msg := new(dns.Msg)
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msg.Id = dns.Id()
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msg.RecursionDesired = rd
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msg.Question = make([]dns.Question, 1)
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msg.Question[0] = *questionMaker(domain, qclass, qtype)
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if edns {
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msg = msg.SetEdns0(1232, false)
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}
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return msg
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}
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// query and receive the response
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// addr must contain dest port
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// func DNSQuery(addr string, domain string, rd bool, qclass uint16, qtype uint16, edns bool) (*dns.Msg, error) {
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func DNSQuery(addr string, opt DNSOptions) (*dns.Msg, error) {
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if opt.Qclass == 0 {
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opt.Qclass = 1
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}
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if opt.Qtype == 0 {
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opt.Qtype = 1
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}
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msg := queryMaker(opt.Domain, opt.RD, opt.Qclass, opt.Qtype, opt.EDNS)
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res, err := dns.Exchange(msg, addr)
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return res, err
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}
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func AsyncDNSQuery(addr string, domain string, rd bool, qclass uint16, qtype uint16, edns bool) error {
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msg := queryMaker(domain, rd, qclass, qtype, edns)
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client := dns.Client{Net: "udp"}
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conn, err := client.Dial(addr)
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if err != nil {
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return err
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}
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defer conn.Close()
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err = conn.WriteMsg(msg)
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if err != nil {
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return err
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}
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return nil
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}
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