From 3d934d0978946fe6313d6d1ddf258f3ae16adc86 Mon Sep 17 00:00:00 2001
From: Conner Fromknecht <conner@lightning.engineering>
Date: Tue, 19 Mar 2019 19:38:09 -0700
Subject: [PATCH] watchtower/wtwire: add DeleteSession and DeleteSessionReply
 message

---
 watchtower/wtwire/delete_session.go       | 45 ++++++++++++++++
 watchtower/wtwire/delete_session_reply.go | 66 +++++++++++++++++++++++
 watchtower/wtwire/message.go              | 15 ++++++
 watchtower/wtwire/wtwire_test.go          | 12 +++++
 4 files changed, 138 insertions(+)
 create mode 100644 watchtower/wtwire/delete_session.go
 create mode 100644 watchtower/wtwire/delete_session_reply.go

diff --git a/watchtower/wtwire/delete_session.go b/watchtower/wtwire/delete_session.go
new file mode 100644
index 00000000..fbe8cfb0
--- /dev/null
+++ b/watchtower/wtwire/delete_session.go
@@ -0,0 +1,45 @@
+package wtwire
+
+import "io"
+
+// DeleteSession is sent from the client to the tower to signal that the tower
+// can delete all session state for the session key used to authenticate the
+// brontide connection. This should be done by the client once all channels that
+// have state updates in the session have been resolved on-chain.
+type DeleteSession struct{}
+
+// Compile-time constraint to ensure DeleteSession implements the wtwire.Message
+// interface.
+var _ Message = (*DeleteSession)(nil)
+
+// Decode deserializes a serialized DeleteSession message stored in the passed
+// io.Reader observing the specified protocol version.
+//
+// This is part of the wtwire.Message interface.
+func (m *DeleteSession) Decode(r io.Reader, pver uint32) error {
+	return nil
+}
+
+// Encode serializes the target DeleteSession message into the passed io.Writer
+// observing the specified protocol version.
+//
+// This is part of the wtwire.Message interface.
+func (m *DeleteSession) Encode(w io.Writer, pver uint32) error {
+	return nil
+}
+
+// MsgType returns the integer uniquely identifying this message type on the
+// wire.
+//
+// This is part of the wtwire.Message interface.
+func (m *DeleteSession) MsgType() MessageType {
+	return MsgDeleteSession
+}
+
+// MaxPayloadLength returns the maximum allowed payload size for a DeleteSession
+// message observing the specified protocol version.
+//
+// This is part of the wtwire.Message interface.
+func (m *DeleteSession) MaxPayloadLength(uint32) uint32 {
+	return 0
+}
diff --git a/watchtower/wtwire/delete_session_reply.go b/watchtower/wtwire/delete_session_reply.go
new file mode 100644
index 00000000..059d189e
--- /dev/null
+++ b/watchtower/wtwire/delete_session_reply.go
@@ -0,0 +1,66 @@
+package wtwire
+
+import "io"
+
+// DeleteSessionCode is an error code returned by a watchtower in response to a
+// DeleteSession message.
+type DeleteSessionCode = ErrorCode
+
+const (
+	// DeleteSessionCodeNotFound is returned when the watchtower does not
+	// know of the requested session. This may indicate an error on the
+	// client side, or that the tower had already deleted the session in a
+	// prior request that the client may not have received.
+	DeleteSessionCodeNotFound DeleteSessionCode = 80
+
+	// TODO(conner): add String method after wtclient is merged
+)
+
+// DeleteSessionReply is a message sent in response to a client's DeleteSession
+// request. The message indicates whether or not the deletion was a success or
+// failure.
+type DeleteSessionReply struct {
+	// Code will be non-zero if the watchtower was not able to delete the
+	// requested session.
+	Code DeleteSessionCode
+}
+
+// A compile time check to ensure DeleteSessionReply implements the
+// wtwire.Message interface.
+var _ Message = (*DeleteSessionReply)(nil)
+
+// Decode deserializes a serialized DeleteSessionReply message stored in the
+// passed io.Reader observing the specified protocol version.
+//
+// This is part of the wtwire.Message interface.
+func (m *DeleteSessionReply) Decode(r io.Reader, pver uint32) error {
+	return ReadElements(r,
+		&m.Code,
+	)
+}
+
+// Encode serializes the target DeleteSessionReply into the passed io.Writer
+// observing the protocol version specified.
+//
+// This is part of the wtwire.Message interface.
+func (m *DeleteSessionReply) Encode(w io.Writer, pver uint32) error {
+	return WriteElements(w,
+		m.Code,
+	)
+}
+
+// MsgType returns the integer uniquely identifying this message type on the
+// wire.
+//
+// This is part of the wtwire.Message interface.
+func (m *DeleteSessionReply) MsgType() MessageType {
+	return MsgDeleteSessionReply
+}
+
+// MaxPayloadLength returns the maximum allowed payload size for a
+// DeleteSessionReply complete message observing the specified protocol version.
+//
+// This is part of the wtwire.Message interface.
+func (m *DeleteSessionReply) MaxPayloadLength(uint32) uint32 {
+	return 2
+}
diff --git a/watchtower/wtwire/message.go b/watchtower/wtwire/message.go
index 364a2dab..192a397c 100644
--- a/watchtower/wtwire/message.go
+++ b/watchtower/wtwire/message.go
@@ -40,6 +40,13 @@ const (
 
 	// MsgStateUpdateReply identifies an encoded StateUpdateReply message.
 	MsgStateUpdateReply MessageType = 305
+
+	// MsgDeleteSession identifies an encoded DeleteSession message.
+	MsgDeleteSession MessageType = 306
+
+	// MsgDeleteSessionReply identifies an encoded DeleteSessionReply
+	// message.
+	MsgDeleteSessionReply MessageType = 307
 )
 
 // String returns a human readable description of the message type.
@@ -55,6 +62,10 @@ func (m MessageType) String() string {
 		return "MsgStateUpdate"
 	case MsgStateUpdateReply:
 		return "MsgStateUpdateReply"
+	case MsgDeleteSession:
+		return "MsgDeleteSession"
+	case MsgDeleteSessionReply:
+		return "MsgDeleteSessionReply"
 	case MsgError:
 		return "Error"
 	default:
@@ -97,6 +108,10 @@ func makeEmptyMessage(msgType MessageType) (Message, error) {
 		msg = &StateUpdate{}
 	case MsgStateUpdateReply:
 		msg = &StateUpdateReply{}
+	case MsgDeleteSession:
+		msg = &DeleteSession{}
+	case MsgDeleteSessionReply:
+		msg = &DeleteSessionReply{}
 	case MsgError:
 		msg = &Error{}
 	default:
diff --git a/watchtower/wtwire/wtwire_test.go b/watchtower/wtwire/wtwire_test.go
index 1dfef1a2..e9b37a55 100644
--- a/watchtower/wtwire/wtwire_test.go
+++ b/watchtower/wtwire/wtwire_test.go
@@ -126,6 +126,18 @@ func TestWatchtowerWireProtocol(t *testing.T) {
 				return mainScenario(&m)
 			},
 		},
+		{
+			msgType: wtwire.MsgDeleteSession,
+			scenario: func(m wtwire.DeleteSession) bool {
+				return mainScenario(&m)
+			},
+		},
+		{
+			msgType: wtwire.MsgDeleteSessionReply,
+			scenario: func(m wtwire.DeleteSessionReply) bool {
+				return mainScenario(&m)
+			},
+		},
 		{
 			msgType: wtwire.MsgError,
 			scenario: func(m wtwire.Error) bool {