Fix NAPTR's length function

Add the 3 bytes for the length byte of the strings.

Close issue #67.

dns_test.go

@@ -144,6 +144,24 @@ func TestPack(t *testing.T) {
 	}
 }
 
+func TestPackNAPTR(t *testing.T) {
+	for _, n := range []string{
+		`apple.com. IN NAPTR   100 50 "se" "SIP+D2U" "" _sip._udp.apple.com.`,
+		`apple.com. IN NAPTR   90 50 "se" "SIP+D2T" "" _sip._tcp.apple.com.`,
+		`apple.com. IN NAPTR   50 50 "se" "SIPS+D2T" "" _sips._tcp.apple.com.`,
+	} {
+		rr, _ := NewRR(n)
+		msg := make([]byte, rr.len())
+		if off, err := PackRR(rr, msg, 0, nil, false); err != nil {
+			t.Logf("Packing failed: %s", err.Error())
+			t.Logf("Length %d, need more than %d\n", rr.len(), off)
+			t.Fail()
+		} else {
+			t.Logf("Buf size needed: %d\n", off)
+		}
+	}
+}
+
 func TestCompressLength(t *testing.T) {
 	m := new(Msg)
 	m.SetQuestion("miek.nl", TypeMX)

msg.go

@@ -1357,6 +1357,7 @@ func (dns *Msg) Pack() (msg []byte, err error) {
 		}
 	}
 	for i := 0; i < len(answer); i++ {
+		println(i, off, len(msg))
 		off, err = PackRR(answer[i], msg, off, compression, dns.Compress)
 		if err != nil {
 			return nil, err

types.go

@@ -583,8 +583,8 @@ func (rr *NAPTR) String() string {
 }
 
 func (rr *NAPTR) len() int {
-	return rr.Hdr.len() + 4 + len(rr.Flags) + len(rr.Service) +
-		len(rr.Regexp) + len(rr.Replacement) + 1
+	return rr.Hdr.len() + 4 + len(rr.Flags) + 1 + len(rr.Service) + 1 +
+		len(rr.Regexp) + 1 + len(rr.Replacement) + 1
 }
 
 // See RFC 4398.