From 71541bc94ecf7ba19e00969b13225bbd4601620e Mon Sep 17 00:00:00 2001
From: Conner Fromknecht <conner@mit.edu>
Date: Tue, 23 Oct 2018 18:28:24 -0700
Subject: [PATCH] watchtower/wtwire/create_session: propose new session

---
 watchtower/wtwire/create_session.go | 78 +++++++++++++++++++++++++++++
 1 file changed, 78 insertions(+)
 create mode 100644 watchtower/wtwire/create_session.go

diff --git a/watchtower/wtwire/create_session.go b/watchtower/wtwire/create_session.go
new file mode 100644
index 00000000..8ee2c906
--- /dev/null
+++ b/watchtower/wtwire/create_session.go
@@ -0,0 +1,78 @@
+package wtwire
+
+import (
+	"io"
+
+	"github.com/lightningnetwork/lnd/lnwallet"
+)
+
+// CreateSession is sent from a client to tower when to negotiate a session, which
+// specifies the total number of updates that can be made, as well as fee rates.
+// An update is consumed by uploading an encrypted blob that contains
+// information required to sweep a revoked commitment transaction.
+type CreateSession struct {
+	// BlobVersion specifies the blob format that must be used by all
+	// updates sent under the session key used to negotiate this session.
+	BlobVersion uint16
+
+	// MaxUpdates is the maximum number of updates the watchtower will honor
+	// for this session.
+	MaxUpdates uint16
+
+	// RewardRate is the fraction of the total balance of the revoked
+	// commitment that the watchtower is entitled to. This value is
+	// expressed in millionths of the total balance.
+	RewardRate uint32
+
+	// SweepFeeRate expresses the intended fee rate to be used when
+	// constructing the justice transaction. All sweep transactions created
+	// for this session must use this value during construction, and the
+	// signatures must implicitly commit to the resulting output values.
+	SweepFeeRate lnwallet.SatPerKWeight
+}
+
+// A compile time check to ensure CreateSession implements the wtwire.Message
+// interface.
+var _ Message = (*CreateSession)(nil)
+
+// Decode deserializes a serialized CreateSession message stored in the passed
+// io.Reader observing the specified protocol version.
+//
+// This is part of the wtwire.Message interface.
+func (m *CreateSession) Decode(r io.Reader, pver uint32) error {
+	return ReadElements(r,
+		&m.BlobVersion,
+		&m.MaxUpdates,
+		&m.RewardRate,
+		&m.SweepFeeRate,
+	)
+}
+
+// Encode serializes the target CreateSession into the passed io.Writer
+// observing the protocol version specified.
+//
+// This is part of the wtwire.Message interface.
+func (m *CreateSession) Encode(w io.Writer, pver uint32) error {
+	return WriteElements(w,
+		m.BlobVersion,
+		m.MaxUpdates,
+		m.RewardRate,
+		m.SweepFeeRate,
+	)
+}
+
+// MsgType returns the integer uniquely identifying this message type on the
+// wire.
+//
+// This is part of the wtwire.Message interface.
+func (m *CreateSession) MsgType() MessageType {
+	return MsgCreateSession
+}
+
+// MaxPayloadLength returns the maximum allowed payload size for a CreateSession
+// complete message observing the specified protocol version.
+//
+// This is part of the wtwire.Message interface.
+func (m *CreateSession) MaxPayloadLength(uint32) uint32 {
+	return 16
+}