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package resolver
import (
"bufio"
"fmt"
"os"
"strings"
)
type NS struct {
Name string
Addr string
}
func LoadHints(path string) ([]NS, error) {
f, err := os.Open(path)
if err != nil {
return nil, fmt.Errorf("hints file %s not found — download from https://www.internic.net/domain/named.root: %w", path, err)
}
defer f.Close()
var nsNames []string
glue := make(map[string]string)
sc := bufio.NewScanner(f)
for sc.Scan() {
fields := strings.Fields(sc.Text())
if len(fields) < 4 || fields[0] == ";" {
continue
}
if fields[0] == "." && fields[2] == "NS" {
nsNames = append(nsNames, fields[3])
}
if fields[2] == "A" {
glue[fields[0]] = fields[3]
}
}
if err := sc.Err(); err != nil {
return nil, err
}
var hints []NS
for _, name := range nsNames {
hints = append(hints, NS{Name: name, Addr: glue[name]})
}
if len(hints) == 0 {
return nil, fmt.Errorf("no root hints parsed from %s", path)
}
return hints, nil
}
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