From ec8d3d51d11f9eb196b9d0765ca8a84c6f225dd1 Mon Sep 17 00:00:00 2001
From: Alex Polvi <alex@polvi.net>
Date: Mon, 15 Oct 2012 18:37:19 +0100
Subject: [PATCH] initial stab at edns update lease
 http://files.dns-sd.org/draft-sekar-dns-ul.txt

---
 README.markdown |  1 +
 client_test.go  | 36 ++++++++++++++++++++++++++++++++++++
 edns.go         | 43 +++++++++++++++++++++++++++++++++++++++++++
 msg.go          |  5 +++++
 4 files changed, 85 insertions(+)

diff --git a/README.markdown b/README.markdown
index 9393ab0d..d950bd4f 100644
--- a/README.markdown
+++ b/README.markdown
@@ -87,6 +87,7 @@ be build with: `make -C ex`, or also with the `go` tool.
 * 5936 - AXFR
 * 6605 - ECDSA
 * xxxx - URI record (draft)
+* xxxx - Dns Update Lease (draft)
 
 ## Loosely based upon
 
diff --git a/client_test.go b/client_test.go
index 1285808f..c8dc8f3e 100644
--- a/client_test.go
+++ b/client_test.go
@@ -99,3 +99,39 @@ func TestClientAXFRMultipleMessages(t *testing.T) {
 		}
 	}
 }
+
+// not really a test, but shows how to use update leases
+func TestUpdateLeaseTSIG(t *testing.T) {
+	m := new(Msg)
+	m.SetUpdate("t.local.ip6.io.")
+	rr, _ := NewRR("t.local.ip6.io. 30 A 127.0.0.1")
+	rrs := make([]RR, 1)
+	rrs[0] = rr
+	m.AddRR(rrs)
+
+	lease_rr := new(RR_OPT)
+	lease_rr.Hdr.Name = "."
+	lease_rr.Hdr.Rrtype = TypeOPT
+	e := new(EDNS0_UPDATE_LEASE)
+	e.Code = EDNS0UPDATELEASE
+	e.Lease = 120
+	lease_rr.Option = append(lease_rr.Option, e)
+	m.Extra = append(m.Extra, lease_rr)
+
+	c := new(Client)
+	m.SetTsig("polvi.", HmacMD5, 300, time.Now().Unix())
+	c.TsigSecret = map[string]string{"polvi.": "pRZgBrBvI4NAHZYhxmhs/Q=="}
+
+	w := new(reply)
+	w.client = c
+	w.addr = "127.0.0.1:53"
+	w.req = m
+
+	if err := w.dial(); err != nil {
+		t.Fail()
+	}
+	if err := w.send(m); err != nil {
+		t.Fail()
+	}
+
+}
diff --git a/edns.go b/edns.go
index 41bd0224..6fb07c93 100644
--- a/edns.go
+++ b/edns.go
@@ -73,6 +73,8 @@ func (rr *RR_OPT) String() string {
 			}
 		case *EDNS0_SUBNET:
 			s += "\n; SUBNET: " + o.String()
+		case *EDNS0_UPDATE_LEASE:
+			s += "\n; LEASE: " + o.String()
 		}
 	}
 	return s
@@ -278,3 +280,44 @@ func (e *EDNS0_SUBNET) String() (s string) {
 	s += "/" + strconv.Itoa(int(e.SourceNetmask)) + "/" + strconv.Itoa(int(e.SourceScope))
 	return
 }
+
+// The UPDATE_LEASE EDNS0 (draft RFC) option is used to tell the server to set
+// an expiration on an update RR. This is helpful for clients that cannot clean
+// up after themselves. This is a draft RFC and more information can be found at
+// http://files.dns-sd.org/draft-sekar-dns-ul.txt 
+//
+//	o := new(dns.RR_OPT)
+//	o.Hdr.Name = "."
+//	o.Hdr.Rrtype = dns.TypeOPT
+//	e := new(dns.EDNS0_UPDATE_LEASE)
+//	e.Code = dns.EDNS0UPDATELEASE
+//	e.Lease = 120 // in seconds
+//	o.Option = append(o.Option, e)
+const EDNS0UPDATELEASE = 0x02
+
+type EDNS0_UPDATE_LEASE struct {
+	Code          uint16 // Always EDNS0UPDATELEASE
+	Lease         uint32
+}
+
+func (e *EDNS0_UPDATE_LEASE) Option() uint16 {
+	return EDNS0UPDATELEASE
+}
+
+// Copied: http://golang.org/src/pkg/net/dnsmsg.go
+func (e *EDNS0_UPDATE_LEASE) pack() ([]byte, error) {
+	lease_byte := make([]byte, 4)
+	lease_byte[0] = byte(e.Lease >> 24)
+	lease_byte[1] = byte(e.Lease >> 16)
+	lease_byte[2] = byte(e.Lease >> 8)
+	lease_byte[3] = byte(e.Lease)
+	return lease_byte, nil
+}
+
+func (e *EDNS0_UPDATE_LEASE) unpack(b []byte) {
+	e.Lease = uint32(b[0])<<24 | uint32(b[1])<<16 | uint32(b[2])<<8 | uint32(b[3])
+}
+
+func (e *EDNS0_UPDATE_LEASE) String() string {
+	return strconv.Itoa(int(e.Lease))
+}
diff --git a/msg.go b/msg.go
index 8b108b3b..f3131b1a 100644
--- a/msg.go
+++ b/msg.go
@@ -699,6 +699,11 @@ 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 EDNS0UPDATELEASE:
+					e := new(EDNS0_UPDATE_LEASE)
+					e.unpack(msg[off1 : off1+int(optlen)])
+					edns = append(edns, e)
+					off = off1 + int(optlen)
 				}
 				fv.Set(reflect.ValueOf(edns))
 				// multiple EDNS codes?