refactor(dns): replace dnsmessage with miekg/dns (#188)

control/dns_utils.go

@@ -6,98 +6,44 @@
 package control
 
 import (
-	"encoding/binary"
 	"fmt"
-	"hash/fnv"
-	"math/rand"
-	"net/netip"
+	"strconv"
 	"strings"
 
-	"golang.org/x/net/dns/dnsmessage"
+	dnsmessage "github.com/miekg/dns"
 )
 
-// FlipDnsQuestionCase is used to reduce dns pollution.
-func FlipDnsQuestionCase(dm *dnsmessage.Message) {
-	if len(dm.Questions) == 0 {
-		return
-	}
-	q := &dm.Questions[0]
-	// For reproducibility, we use dm.ID as input and add some entropy to make the results more discrete.
-	h := fnv.New64()
-	var buf [4]byte
-	binary.BigEndian.PutUint16(buf[:], dm.ID)
-	h.Write(buf[:2])
-	binary.BigEndian.PutUint32(buf[:], 20230204) // entropy
-	h.Write(buf[:])
-	r := rand.New(rand.NewSource(int64(h.Sum64())))
-	perm := r.Perm(int(q.Name.Length))
-	for i := 0; i < int(q.Name.Length/3); i++ {
-		j := perm[i]
-		// Upper to lower; lower to upper.
-		if q.Name.Data[j] >= 'a' && q.Name.Data[j] <= 'z' {
-			q.Name.Data[j] -= 'a' - 'A'
-		} else if q.Name.Data[j] >= 'A' && q.Name.Data[j] <= 'Z' {
-			q.Name.Data[j] += 'a' - 'A'
-		}
-	}
-}
-
-// EnsureAdditionalOpt makes sure there is additional record OPT in the request.
-func EnsureAdditionalOpt(dm *dnsmessage.Message, isReqAdd bool) (bool, error) {
-	// Check healthy resp.
-	if isReqAdd == dm.Response || dm.RCode != dnsmessage.RCodeSuccess || len(dm.Questions) == 0 {
-		return false, UnsupportedQuestionTypeError
-	}
-	q := dm.Questions[0]
-	switch q.Type {
-	case dnsmessage.TypeA, dnsmessage.TypeAAAA:
-	default:
-		return false, UnsupportedQuestionTypeError
-	}
-
-	for _, ad := range dm.Additionals {
-		if ad.Header.Type == dnsmessage.TypeOPT {
-			// Already has additional record OPT.
-			return true, nil
-		}
-	}
-	if !isReqAdd {
-		return false, nil
-	}
-	// Add one.
-	dm.Additionals = append(dm.Additionals, dnsmessage.Resource{
-		Header: dnsmessage.ResourceHeader{
-			Name:  dnsmessage.MustNewName("."),
-			Type:  dnsmessage.TypeOPT,
-			Class: 512, TTL: 0, Length: 0,
-		},
-		Body: &dnsmessage.OPTResource{
-			Options: nil,
-		},
-	})
-	return false, nil
-}
-
 type RscWrapper struct {
-	Rsc dnsmessage.Resource
+	Rsc dnsmessage.RR
 }
 
 func (w RscWrapper) String() string {
 	var strBody string
-	switch body := w.Rsc.Body.(type) {
-	case *dnsmessage.AResource:
-		strBody = netip.AddrFrom4(body.A).String()
-	case *dnsmessage.AAAAResource:
-		strBody = netip.AddrFrom16(body.AAAA).String()
+	switch body := w.Rsc.(type) {
+	case *dnsmessage.A:
+		strBody = body.A.String()
+	case *dnsmessage.AAAA:
+		strBody = body.AAAA.String()
+	case *dnsmessage.CNAME:
+		strBody = body.Target
 	default:
-		strBody = body.GoString()
+		strBody = body.String()
 	}
-	return fmt.Sprintf("%v(%v): %v", w.Rsc.Header.Name.String(), w.Rsc.Header.Type.String(), strBody)
+	return fmt.Sprintf("%v(%v): %v", w.Rsc.Header().Name, QtypeToString(w.Rsc.Header().Rrtype), strBody)
 }
-func FormatDnsRsc(ans []dnsmessage.Resource) string {
+
+func FormatDnsRsc(ans []dnsmessage.RR) string {
 	var w []string
 	for _, a := range ans {
 		w = append(w, RscWrapper{Rsc: a}.String())
 	}
 	return strings.Join(w, "; ")
 }
+
+func QtypeToString(qtype uint16) string {
+	str, ok := dnsmessage.TypeToString[qtype]
+	if !ok {
+		str = strconv.Itoa(int(qtype))
+	}
+	return str
+}