package main

// Print the DNSKEY records of a domain as DS records
// Twist with all the other tools that can do this. Do
// this directly from the internet.
// (c) Miek Gieben - 2011
import (
	"dns"
        "os"
        "fmt"
)

func main() {
	conf, err := dns.ClientConfigFromFile("/etc/resolv.conf")
        if len(os.Args) != 2 || err != nil {
                fmt.Printf("%s DOMAIN\n", os.Args[0])
                os.Exit(1)
        }
        m := new(dns.Msg)
        m.SetQuestion(os.Args[1], dns.TypeDNSKEY)

        // Set EDNS0's Do bit
        e := new(dns.RR_OPT)
        e.Hdr.Name = "."
        e.Hdr.Rrtype = dns.TypeOPT
        e.SetUDPSize(2048)
        e.SetDo()
        m.Extra = append(m.Extra, e)

        c := dns.NewClient()
        r, _ := c.Exchange(m, conf.Servers[0])
        if r == nil {
                fmt.Printf("*** no answer received for %s\n", os.Args[1])
                os.Exit(1)
        }

        if r.Rcode != dns.RcodeSuccess {
                fmt.Printf(" *** invalid answer name %s after DNSKEY query for %s\n", os.Args[1], os.Args[1])
                os.Exit(1)
        }
        // Stuff must be in the answer section, check len(r.Answer)
        for _, k := range r.Answer {
                // Foreach key would need to provide a DS records, both sha1 and sha256
                if key, ok := k.(*dns.RR_DNSKEY); ok {
                        key.Hdr.Ttl = 0
                        ds := key.ToDS(dns.SHA1)
                        fmt.Printf("%v\n", ds)
                        ds = key.ToDS(dns.SHA256)
                        fmt.Printf("%v\n", ds)
                        ds = key.ToDS(dns.SHA384)
                        fmt.Printf("%v\n", ds)
                }
        }
}