100 lines
2.4 KiB
Go
100 lines
2.4 KiB
Go
package main
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// a (simple) dig-like query tool in 99 lines of Go
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import (
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"net"
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"dns"
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"dns/resolver"
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"os"
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"flag"
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"fmt"
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"strings"
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)
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func main() {
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var dnssec *bool = flag.Bool("dnssec", false, "Request DNSSEC records")
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var port *string = flag.String("port", "53", "Set the query port")
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var aa *bool = flag.Bool("aa", false, "Set AA flag in query")
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var ad *bool = flag.Bool("ad", false, "Set AD flag in query")
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var cd *bool = flag.Bool("cd", false, "Set CD flag in query")
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var rd *bool = flag.Bool("rd", true, "Unset RD flag in query")
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var tcp *bool = flag.Bool("tcp", false, "TCP mode")
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flag.Usage = func() {
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fmt.Fprintf(os.Stderr, "Usage: %s [@server] [qtype] [qclass] [name ...]\n", os.Args[0])
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flag.PrintDefaults()
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}
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nameserver := "@127.0.0.1" // Default nameserver
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qtype := uint16(dns.TypeA) // Default qtype
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qclass := uint16(dns.ClassINET) // Default qclass
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var qname []string
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flag.Parse()
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FLAGS:
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for i := 0; i < flag.NArg(); i++ {
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// If it starts with @ it is a nameserver
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if flag.Arg(i)[0] == '@' {
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nameserver = flag.Arg(i)
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continue FLAGS
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}
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// If it looks like a class, it is a class
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for k, v := range dns.Class_str {
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if v == strings.ToUpper(flag.Arg(i)) {
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qclass = k
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continue FLAGS
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}
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}
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// And if it looks like type, it is a type
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for k, v := range dns.Rr_str {
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if v == strings.ToUpper(flag.Arg(i)) {
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qtype = k
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continue FLAGS
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}
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}
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// Anything else is a qname
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qname = append(qname, flag.Arg(i))
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}
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r := new(resolver.Resolver)
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r.Timeout = 2
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r.Port = *port
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r.Tcp = *tcp
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r.Attempts = 1
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qr := resolver.NewQuerier(r)
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// @server may be a name, resolv that
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var err os.Error
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nameserver = string([]byte(nameserver)[1:]) // chop off @
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_, addr, err := net.LookupHost(nameserver)
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if err == nil {
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r.Servers = addr
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} else {
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r.Servers = []string{nameserver}
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}
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m := new(dns.Msg)
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m.MsgHdr.Authoritative = *aa
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m.MsgHdr.AuthenticatedData = *ad
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m.MsgHdr.CheckingDisabled = *cd
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m.MsgHdr.RecursionDesired = *rd
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m.Question = make([]dns.Question, 1)
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if *dnssec {
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opt := new(dns.RR_OPT)
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opt.Hdr = dns.RR_Header{Name: "", Rrtype: dns.TypeOPT}
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opt.Version(0, true)
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opt.DoBit(true, true)
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opt.UDPSize(4096, true)
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m.Extra = make([]dns.RR, 1)
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m.Extra[0] = opt
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}
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for _, v := range qname {
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m.Question[0] = dns.Question{v, qtype, qclass}
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qr <- resolver.DnsMsg{m, nil}
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in := <-qr
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if in.Dns != nil {
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fmt.Printf("%v\n", in.Dns)
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}
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}
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qr <- resolver.DnsMsg{nil, nil}
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<-qr
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}
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