Support the new RFC6891 EDNS0 SUBNET option code

Also keep support for the old draft code

edns.go

@@ -14,7 +14,7 @@
 //	o.Hdr.Rrtype = dns.TypeOPT
 //
 // The rdata of an OPT RR consists out of a slice of EDNS0 interfaces. Currently
-// only a few have been standardized: EDNS0_NSID (RFC 5001) and EDNS0_SUBNET (draft). Note that
+// only a few have been standardized: EDNS0_NSID (RFC 5001) and EDNS0_SUBNET (RFC 6891). Note that
 // these options may be combined in an OPT RR.
 // Basic use pattern for a server to check if (and which) options are set:
 //
@@ -38,14 +38,15 @@ import (
 
 // EDNS0 Option codes.
 const (
-	EDNS0LLQ    = 0x1    // long lived queries: http://tools.ietf.org/html/draft-sekar-dns-llq-01
-	EDNS0UL     = 0x2    // update lease draft: http://files.dns-sd.org/draft-sekar-dns-ul.txt
-	EDNS0NSID   = 0x3    // nsid (RFC5001)
-	EDNS0SUBNET = 0x50fa // client-subnet draft: http://tools.ietf.org/html/draft-vandergaast-edns-client-subnet-01
-	EDNS0DAU    = 0x5    // DNSSEC Algorithm Understood
-	EDNS0DHU    = 0x6    // DS Hash Understood
-	EDNS0N3U    = 0x7    // NSEC3 Hash Understood
-	_DO         = 1 << 7 // dnssec ok
+	EDNS0LLQ         = 0x1    // long lived queries: http://tools.ietf.org/html/draft-sekar-dns-llq-01
+	EDNS0UL          = 0x2    // update lease draft: http://files.dns-sd.org/draft-sekar-dns-ul.txt
+	EDNS0NSID        = 0x3    // nsid (RFC5001)
+	EDNS0DAU         = 0x5    // DNSSEC Algorithm Understood
+	EDNS0DHU         = 0x6    // DS Hash Understood
+	EDNS0N3U         = 0x7    // NSEC3 Hash Understood
+	EDNS0SUBNET      = 0x8    // client-subnet (RFC6891)
+	EDNS0SUBNETDRAFT = 0x50fa // client-subnet draft: http://tools.ietf.org/html/draft-vandergaast-edns-client-subnet-01
+	_DO              = 1 << 7 // dnssec ok
 )
 
 type OPT struct {
@@ -80,6 +81,9 @@ func (rr *OPT) String() string {
 			}
 		case *EDNS0_SUBNET:
 			s += "\n; SUBNET: " + o.String()
+			if o.(*EDNS0_SUBNET).DraftOption {
+				s += " (draft)"
+			}
 		case *EDNS0_UL:
 			s += "\n; UPDATE LEASE: " + o.String()
 		case *EDNS0_LLQ:
@@ -220,10 +224,15 @@ type EDNS0_SUBNET struct {
 	SourceNetmask uint8
 	SourceScope   uint8
 	Address       net.IP
+	DraftOption   bool
 }
 
 func (e *EDNS0_SUBNET) Option() uint16 {
-	return EDNS0SUBNET
+	if e.DraftOption {
+		return EDNS0SUBNETDRAFT
+	} else {
+		return EDNS0SUBNET
+	}
 }
 
 func (e *EDNS0_SUBNET) pack() ([]byte, error) {

ex/q/q.go

@@ -44,6 +44,7 @@ func main() {
 	tcp := flag.Bool("tcp", false, "TCP mode")
 	nsid := flag.Bool("nsid", false, "set edns nsid option")
 	client := flag.String("client", "", "set edns client-subnet option")
+	clientdraftcode := flag.Bool("clientdraft", false, "set edns client-subnet option using the draft option code")
 	//serial := flag.Int("serial", 0, "perform an IXFR with this serial")
 	flag.Usage = func() {
 		fmt.Fprintf(os.Stderr, "Usage: %s [options] [@server] [qtype] [qclass] [name ...]\n", os.Args[0])
@@ -177,6 +178,9 @@ Flags:
 		if *client != "" {
 			e := new(dns.EDNS0_SUBNET)
 			e.Code = dns.EDNS0SUBNET
+			if *clientdraftcode {
+				e.DraftOption = true
+			}
 			e.SourceScope = 0
 			e.Address = net.ParseIP(*client)
 			if e.Address == nil {

msg.go

@@ -786,11 +786,14 @@ func unpackStructValue(val reflect.Value, msg []byte, off int) (off1 int, err er
 					e.unpack(msg[off1 : off1+int(optlen)])
 					edns = append(edns, e)
 					off = off1 + int(optlen)
-				case EDNS0SUBNET:
+				case EDNS0SUBNET, EDNS0SUBNETDRAFT:
 					e := new(EDNS0_SUBNET)
 					e.unpack(msg[off1 : off1+int(optlen)])
 					edns = append(edns, e)
 					off = off1 + int(optlen)
+					if code == EDNS0SUBNETDRAFT {
+						e.DraftOption = true
+					}
 				case EDNS0UL:
 					e := new(EDNS0_UL)
 					e.unpack(msg[off1 : off1+int(optlen)])