switch to miekg/dns for better results

cmd/domaincheckbot/dns/domain.go

@@ -1,8 +1,11 @@
 package dns
 
 import (
+	"fmt"
+	"github.com/miekg/dns"
 	"net"
-	"sort"
+	"slices"
+	"strings"
 )
 
 type Domain struct {
@@ -10,30 +13,63 @@ type Domain struct {
 	NS   []string
 }
 
-func CheckDomain(domain string) Domain {
-	nameservers, err := net.LookupNS(domain)
+func CheckDomain(domain, tld string) Domain {
+	nameservers := []string{}
+	// Create a new DNS message
+	m := new(dns.Msg)
+	// Set the question section of the message with the domain and query type
+	m.SetQuestion(dns.Fqdn(fmt.Sprintf("%v.%v", domain, tld)), dns.TypeNS)
 
-	if len(nameservers) > 0 && err == nil {
+	// Create a DNS client
+	c := new(dns.Client)
+	// Define the .com TLD server
+	ns, err := net.LookupNS(tld)
+	if err != nil {
 		return Domain{
-			Name: domain,
-			NS:   nsToArray(nameservers),
+			Name: domain + "." + tld,
+			NS:   nameservers,
 		}
 	}
+	var tldServer string
+	if len(ns) > 0 {
+		tldServer = strings.Trim(ns[0].Host, ".") + ":53"
+	} else {
+		//log.Fatalf("Could not resolve %v", tld)
+		return Domain{
+			Name: domain + "." + tld,
+			NS:   nameservers,
+		}
+	}
+
+	// Send the DNS query to the TLD server
+	r, _, err := c.Exchange(m, tldServer)
+	if err != nil {
+		//log.Fatalf("Failed to query the TLD server: %v", err)
+		return Domain{
+			Name: domain + "." + tld,
+			NS:   nameservers,
+		}
+	}
+
+	// Check for response errors
+	if r.Rcode != dns.RcodeSuccess {
+		//log.Fatalf("Failed to get a valid response: %v", r.Rcode)
+		return Domain{
+			Name: domain + "." + tld,
+			NS:   nameservers,
+		}
+	}
+
+	// Print the nameservers from the response
+	for _, ans := range r.Ns {
+		if ns, ok := ans.(*dns.NS); ok {
+			nameservers = append(nameservers, strings.ToLower(ns.Ns))
+		}
+	}
+
+	slices.Sort(nameservers)
 	return Domain{
-		Name: domain,
-		NS:   []string{},
+		Name: domain + "." + tld,
+		NS:   nameservers,
 	}
 }
-
-func nsToArray(nameservers []*net.NS) []string {
-	var nsArray []string
-	for _, nameserver := range nameservers {
-		nsArray = append(nsArray, nameserver.Host)
-	}
-
-	sort.SliceStable(nsArray, func(i, j int) bool {
-		return nsArray[i] < nsArray[j]
-	})
-
-	return nsArray
-}