Move makeDataOpt into edns.go (#1273)

Make it more obvious that these two lists (const, and case) need to be
in sync.

Also sort the list to match the const sorting.

Signed-off-by: Miek Gieben <miek@miek.nl>

edns.go

@@ -28,6 +28,41 @@ const (
 	_DO               = 1 << 15 // DNSSEC OK
 )
 
+// makeDataOpt is used to unpack the EDNS0 option(s) from a message.
+func makeDataOpt(code uint16) EDNS0 {
+	// All the EDNS0.* constants above need to be in this switch.
+	switch code {
+	case EDNS0LLQ:
+		return new(EDNS0_LLQ)
+	case EDNS0UL:
+		return new(EDNS0_UL)
+	case EDNS0NSID:
+		return new(EDNS0_NSID)
+	case EDNS0DAU:
+		return new(EDNS0_DAU)
+	case EDNS0DHU:
+		return new(EDNS0_DHU)
+	case EDNS0N3U:
+		return new(EDNS0_N3U)
+	case EDNS0SUBNET:
+		return new(EDNS0_SUBNET)
+	case EDNS0EXPIRE:
+		return new(EDNS0_EXPIRE)
+	case EDNS0COOKIE:
+		return new(EDNS0_COOKIE)
+	case EDNS0TCPKEEPALIVE:
+		return new(EDNS0_TCP_KEEPALIVE)
+	case EDNS0PADDING:
+		return new(EDNS0_PADDING)
+	case EDNS0EDE:
+		return new(EDNS0_EDE)
+	default:
+		e := new(EDNS0_LOCAL)
+		e.Code = code
+		return e
+	}
+}
+
 // OPT is the EDNS0 RR appended to messages to convey extra (meta) information.
 // See RFC 6891.
 type OPT struct {

msg_helpers.go

@@ -438,39 +438,6 @@ Option:
 	return edns, off, nil
 }
 
-func makeDataOpt(code uint16) EDNS0 {
-	switch code {
-	case EDNS0NSID:
-		return new(EDNS0_NSID)
-	case EDNS0SUBNET:
-		return new(EDNS0_SUBNET)
-	case EDNS0COOKIE:
-		return new(EDNS0_COOKIE)
-	case EDNS0EXPIRE:
-		return new(EDNS0_EXPIRE)
-	case EDNS0UL:
-		return new(EDNS0_UL)
-	case EDNS0LLQ:
-		return new(EDNS0_LLQ)
-	case EDNS0DAU:
-		return new(EDNS0_DAU)
-	case EDNS0DHU:
-		return new(EDNS0_DHU)
-	case EDNS0N3U:
-		return new(EDNS0_N3U)
-	case EDNS0PADDING:
-		return new(EDNS0_PADDING)
-	case EDNS0EDE:
-		return new(EDNS0_EDE)
-	case EDNS0TCPKEEPALIVE:
-		return new(EDNS0_TCP_KEEPALIVE)
-	default:
-		e := new(EDNS0_LOCAL)
-		e.Code = code
-		return e
-	}
-}
-
 func packDataOpt(options []EDNS0, msg []byte, off int) (int, error) {
 	for _, el := range options {
 		b, err := el.pack()