dh

Overview ¶

Package dh implements RFC 2930 Diffie-Hellman key exchange functions.

Example client:

import (
        "fmt"
        "net"
        "time"

        "github.com/tidalf/tsig/dh"
        "github.com/miekg/dns"
)

func main() {
        host := "ns.example.com"

        d, err := dh.New()
        if err != nil {
                panic(err)
        }
        defer d.Close()

        // Negotiate a key with the chosen server
        keyname, mac, _, err := d.NegotiateKey(host, "tsig.example.com.", dns.HmacMD5, "k9uK5qsPfbBxvVuldwzYww==")
        if err != nil {
                panic(err)
        }

        client := &dns.Client{
                Net:        "tcp",
                TsigSecret: map[string]string{*keyname: *mac},
        }

        // Use the DNS client as normal

        msg := new(dns.Msg)
        msg.SetUpdate(dns.Fqdn("example.com"))

        insert, err := dns.NewRR("test.example.com. 300 A 192.0.2.1")
        if err != nil {
                panic(err)
        }
        msg.Insert([]dns.RR{insert})

        msg.SetTsig(*keyname, dns.HmacMD5, 300, time.Now().Unix())

        rr, _, err := client.Exchange(msg, net.JoinHostPort(host, "53"))
        if err != nil {
                panic(err)
        }

        if rr.Rcode != dns.RcodeSuccess {
                fmt.Printf("DNS error: %s (%d)\n", dns.RcodeToString[rr.Rcode], rr.Rcode)
        }

        // Revoke the key
        err = d.DeleteKey(keyname)
        if err != nil {
                panic(err)
        }
}