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main.go
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main.go
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package main
import (
"bytes"
_ "embed"
"fmt"
"io"
"net/http"
"net/netip"
"os"
"sort"
"text/template"
"github.com/miekg/dns"
)
//go:embed roothints.go.tmpl
var roothintsgotmpl string
type Roots struct {
Roots4 []netip.Addr
Roots6 []netip.Addr
}
func main() {
resp, err := http.Get("https://www.internic.net/domain/named.root")
if err == nil {
defer resp.Body.Close()
var body []byte
if body, err = io.ReadAll(resp.Body); err == nil {
var root4, root6 []netip.Addr
zp := dns.NewZoneParser(bytes.NewReader(body), "", "")
for rr, ok := zp.Next(); ok; rr, ok = zp.Next() {
switch rr := rr.(type) {
case *dns.A:
if ip, ok := netip.AddrFromSlice(rr.A); ok {
if ip = ip.Unmap(); ip.Is4() {
root4 = append(root4, ip)
ip.AsSlice()
if !netip.AddrFrom4(ip.As4()).Is4() {
panic("not 4")
}
}
}
case *dns.AAAA:
if ip, ok := netip.AddrFromSlice(rr.AAAA); ok {
root6 = append(root6, ip)
}
}
}
sort.Slice(root4, func(i, j int) bool { return root4[i].Less(root4[j]) })
sort.Slice(root6, func(i, j int) bool { return root6[i].Less(root6[j]) })
if err = zp.Err(); err == nil {
var of *os.File
if len(os.Args) < 2 {
of = os.Stdout
} else {
if of, err = os.Create(os.Args[1]); err == nil {
defer of.Close()
}
}
if err == nil {
var t *template.Template
if t, err = template.New("").Parse(roothintsgotmpl); err == nil {
err = t.Execute(of, Roots{Roots4: root4, Roots6: root6})
}
}
}
}
}
if err != nil {
fmt.Fprintln(os.Stderr, err)
os.Exit(1)
}
}