nameservers configuration handled

cmd/dnshunter/runner.go

@@ -1,20 +1,81 @@
 package main
 
 import (
+	"encoding/json"
 	"fmt"
+	"net"
+	"os"
+	"strings"
 
 	"github.com/5amu/dnshunter/internal"
+	"github.com/5amu/dnshunter/internal/common"
+	"github.com/5amu/dnshunter/internal/output"
 	"github.com/miekg/dns"
 )
 
 func run(outfile string, nsfile string, domain string) error {
-
 	c := new(dns.Client)
+
+	nameservers, err := getNameservers(domain, nsfile)
+	if err != nil {
+		return err
+	}
+	fmt.Println(nameservers)
+
+	var results []*output.CheckOutput
 	for _, check := range internal.CheckList {
 		check.Init(c)
-		check.Start("google.com", []string{})
-		fmt.Println(check.Results())
+		check.Start(domain, nameservers)
+
+		r := check.Results()
+		results = append(results, r)
+		fmt.Println(r)
+	}
+
+	if outfile != "" {
+		if data, err := json.Marshal(results); err != nil {
+			return err
+		} else {
+			if err := os.WriteFile(outfile, data, os.ModeAppend); err != nil {
+				return err
+			}
+		}
 	}
 
 	return nil
 }
+
+func getNameservers(domain string, nsfile string) ([]string, error) {
+	if data, err := os.ReadFile(nsfile); err != nil || nsfile != "" {
+		return nameserversFromDNS(domain)
+	} else {
+		return strings.Split(string(data), "\n"), nil
+	}
+}
+
+func nameserversFromDNS(domain string) (result []string, err error) {
+	c := new(dns.Client)
+
+	m := new(dns.Msg)
+	m.SetQuestion(dns.Fqdn(domain), dns.TypeNS)
+	m.RecursionDesired = true
+
+	r, _, err := c.Exchange(m, net.JoinHostPort(common.DefaultNameserver, "53"))
+	if err != nil {
+		return nil, err
+	}
+
+	if r.Rcode != dns.RcodeSuccess {
+		return nil, fmt.Errorf("invalid answer from %v after NS query for %v", common.DefaultNameserver, domain)
+	}
+
+	for _, r := range r.Answer {
+		// google.com.	14332	IN	NS	ns3.google.com.
+		splitted := strings.Split(r.String(), "\t")
+		last := splitted[len(splitted)-1]
+
+		result = append(result, last)
+	}
+
+	return result, nil
+}