discovery+funding: add 'AnnounceSignature' proof exchange

Add the interaction between nodes of announce signature messages, which
will allow us to exhcnage the half channel announcemen proofs later.

discovery/utils.go

@@ -0,0 +1,93 @@
+package discovery
+
+import (
+	"encoding/binary"
+
+	"github.com/lightningnetwork/lnd/channeldb"
+	"github.com/lightningnetwork/lnd/lnwire"
+)
+
+// newProofKey constructs new announcement signature message key.
+func newProofKey(chanID uint64, isRemote bool) waitingProofKey {
+	return waitingProofKey{
+		chanID:   chanID,
+		isRemote: isRemote,
+	}
+}
+
+// ToBytes represents the key in the byte format.
+func (k waitingProofKey) ToBytes() []byte {
+	var key [10]byte
+
+	var b uint8
+	if k.isRemote {
+		b = 0
+	} else {
+		b = 1
+	}
+
+	binary.BigEndian.PutUint64(key[:], k.chanID)
+	key[9] = b
+
+	return key[:]
+}
+
+// createChanAnnouncement helper function which creates the channel announcement
+// by the given channeldb objects.
+func createChanAnnouncement(chanProof *channeldb.ChannelAuthProof,
+	chanInfo *channeldb.ChannelEdgeInfo,
+	e1, e2 *channeldb.ChannelEdgePolicy) (
+	*lnwire.ChannelAnnouncement,
+	*lnwire.ChannelUpdateAnnouncement,
+	*lnwire.ChannelUpdateAnnouncement) {
+	// First, using the parameters of the channel, along with the
+	// channel authentication chanProof, we'll create re-create the
+	// original authenticated channel announcement.
+	chanID := lnwire.NewShortChanIDFromInt(chanInfo.ChannelID)
+	chanAnn := &lnwire.ChannelAnnouncement{
+		NodeSig1:       chanProof.NodeSig1,
+		NodeSig2:       chanProof.NodeSig2,
+		ShortChannelID: chanID,
+		BitcoinSig1:    chanProof.BitcoinSig1,
+		BitcoinSig2:    chanProof.BitcoinSig2,
+		NodeID1:        chanInfo.NodeKey1,
+		NodeID2:        chanInfo.NodeKey2,
+		BitcoinKey1:    chanInfo.BitcoinKey1,
+		BitcoinKey2:    chanInfo.BitcoinKey2,
+	}
+
+	// We'll unconditionally queue the channel's existence chanProof as
+	// it will need to be processed before either of the channel
+	// update networkMsgs.
+
+	// Since it's up to a node's policy as to whether they
+	// advertise the edge in dire direction, we don't create an
+	// advertisement if the edge is nil.
+	var edge1Ann, edge2Ann *lnwire.ChannelUpdateAnnouncement
+	if e1 != nil {
+		edge1Ann = &lnwire.ChannelUpdateAnnouncement{
+			Signature:                 e1.Signature,
+			ShortChannelID:            chanID,
+			Timestamp:                 uint32(e1.LastUpdate.Unix()),
+			Flags:                     0,
+			TimeLockDelta:             e1.TimeLockDelta,
+			HtlcMinimumMsat:           uint32(e1.MinHTLC),
+			FeeBaseMsat:               uint32(e1.FeeBaseMSat),
+			FeeProportionalMillionths: uint32(e1.FeeProportionalMillionths),
+		}
+	}
+	if e2 != nil {
+		edge2Ann = &lnwire.ChannelUpdateAnnouncement{
+			Signature:                 e2.Signature,
+			ShortChannelID:            chanID,
+			Timestamp:                 uint32(e2.LastUpdate.Unix()),
+			Flags:                     1,
+			TimeLockDelta:             e2.TimeLockDelta,
+			HtlcMinimumMsat:           uint32(e2.MinHTLC),
+			FeeBaseMsat:               uint32(e2.FeeBaseMSat),
+			FeeProportionalMillionths: uint32(e2.FeeProportionalMillionths),
+		}
+	}
+
+	return chanAnn, edge1Ann, edge2Ann
+}