lnwire: separate ChannelID into a distinct struct, add tests

This commit separates out the ChannelID into a new file, with
additional helper methods for conversion and formatting. With this
commit, the struct is now more general purpose and can be used in the
new routing package, database, and other related sub-systems.

lnwire/channel_announcement.go

@@ -3,35 +3,13 @@ package lnwire
 import (
 	"bytes"
 	"fmt"
+	"io"
+
 	"github.com/go-errors/errors"
 	"github.com/roasbeef/btcd/btcec"
 	"github.com/roasbeef/btcd/wire"
-	"io"
 )
 
-// ChannelID represent the set of data which is needed to retrieve all
-// necessary data to validate the channel existance.
-type ChannelID struct {
-	// BlockHeight is the height of the block where funding
-	// transaction located.
-	// NOTE: This field is limited to 3 bytes.
-	BlockHeight uint32
-
-	// TxIndex is a position of funding transaction within a block.
-	// NOTE: This field is limited to 3 bytes.
-	TxIndex uint32
-
-	// TxPosition indicating transaction output which pays to the
-	// channel.
-	TxPosition uint16
-}
-
-func (c *ChannelID) String() string {
-	return fmt.Sprintf("BlockHeight:\t\t\t%v\n", c.BlockHeight) +
-		fmt.Sprintf("TxIndex:\t\t\t%v\n", c.TxIndex) +
-		fmt.Sprintf("TxPosition:\t\t\t%v\n", c.TxPosition)
-}
-
 // ChannelAnnouncement message is used to announce the existence of a channel
 // between two peers in the overlay, which is propagated by the discovery
 // service over broadcast handler.
@@ -200,7 +178,7 @@ func (c *ChannelAnnouncement) String() string {
 	return fmt.Sprintf("\n--- Begin ChannelAnnouncement ---\n") +
 		fmt.Sprintf("FirstNodeSig:\t\t%v\n", c.FirstNodeSig) +
 		fmt.Sprintf("SecondNodeSig:\t\t%v\n", c.SecondNodeSig) +
-		fmt.Sprintf("ChannelID:\t\t%v\n", c.ChannelID.String()) +
+		fmt.Sprintf("ChannelID:\t\t%v\n", c.ChannelID.ToUint64()) +
 		fmt.Sprintf("FirstBitcoinSig:\t\t%v\n", c.FirstBitcoinSig) +
 		fmt.Sprintf("SecondBitcoinSig:\t\t%v\n", c.SecondBitcoinSig) +
 		fmt.Sprintf("FirstNodeSig:\t\t%v\n", c.FirstNodeSig) +

lnwire/channel_announcement_test.go

@@ -2,10 +2,11 @@ package lnwire
 
 import (
 	"bytes"
-	"github.com/roasbeef/btcd/btcec"
-	"github.com/roasbeef/btcd/wire"
 	"reflect"
 	"testing"
+
+	"github.com/roasbeef/btcd/btcec"
+	"github.com/roasbeef/btcd/wire"
 )
 
 func TestChannelAnnoucementEncodeDecode(t *testing.T) {

lnwire/channel_id.go

@@ -0,0 +1,40 @@
+package lnwire
+
+// ChannelID represent the set of data which is needed to retrieve all
+// necessary data to validate the channel existence.
+type ChannelID struct {
+	// BlockHeight is the height of the block where funding transaction
+	// located.
+	//
+	// NOTE: This field is limited to 3 bytes.
+	BlockHeight uint32
+
+	// TxIndex is a position of funding transaction within a block.
+	//
+	// NOTE: This field is limited to 3 bytes.
+	TxIndex uint32
+
+	// TxPosition indicating transaction output which pays to the
+	// channel.
+	TxPosition uint16
+}
+
+// NewChanIDFromInt returns a new ChannelID which is the decoded version of the
+// compact channel ID encoded within the uint64. The format of the compact
+// channel ID is as follows: 3 bytes for the block height, 3 bytes for the
+// transaction index, and 2 bytes for the output index.
+func NewChanIDFromInt(chanID uint64) ChannelID {
+	return ChannelID{
+		BlockHeight: uint32(chanID >> 40),
+		TxIndex:     uint32(chanID>>16) & 0xFFFFFF,
+		TxPosition:  uint16(chanID),
+	}
+}
+
+// ToUint64 converts the ChannelID into a compact format encoded within a
+// uint64 (8 bytes).
+func (c *ChannelID) ToUint64() uint64 {
+	// TODO(roasbeef): explicit error on overflow?
+	return ((uint64(c.BlockHeight) << 40) | (uint64(c.TxIndex) << 16) |
+		(uint64(c.TxPosition)))
+}

lnwire/channel_id_test.go

@@ -0,0 +1,39 @@
+package lnwire
+
+import (
+	"reflect"
+	"testing"
+
+	"github.com/davecgh/go-spew/spew"
+)
+
+func TestChannelIDEncoding(t *testing.T) {
+	var testCases = []ChannelID{
+		{
+			BlockHeight: (1 << 24) - 1,
+			TxIndex:     (1 << 24) - 1,
+			TxPosition:  (1 << 16) - 1,
+		},
+		{
+			BlockHeight: 2304934,
+			TxIndex:     2345,
+			TxPosition:  5,
+		},
+		{
+			BlockHeight: 9304934,
+			TxIndex:     2345,
+			TxPosition:  5233,
+		},
+	}
+
+	for _, testCase := range testCases {
+		chanInt := testCase.ToUint64()
+
+		newChanID := NewChanIDFromInt(chanInt)
+
+		if !reflect.DeepEqual(testCase, newChanID) {
+			t.Fatalf("chan ID's don't match: expected %v got %v",
+				spew.Sdump(testCase), spew.Sdump(newChanID))
+		}
+	}
+}

lnwire/channel_update_announcement.go

@@ -158,7 +158,7 @@ func (c *ChannelUpdateAnnouncement) MaxPayloadLength(pver uint32) uint32 {
 func (c *ChannelUpdateAnnouncement) String() string {
 	return fmt.Sprintf("\n--- Begin ChannelUpdateAnnouncement ---\n") +
 		fmt.Sprintf("Signature:\t\t%v\n", c.Signature) +
-		fmt.Sprintf("ChannelID:\t\t%v\n", c.ChannelID.String()) +
+		fmt.Sprintf("ChannelID:\t\t%v\n", c.ChannelID.ToUint64()) +
 		fmt.Sprintf("Timestamp:\t\t%v\n", c.Timestamp) +
 		fmt.Sprintf("Flags:\t\t%v\n", c.Flags) +
 		fmt.Sprintf("Expiry:\t\t%v\n", c.Expiry) +

lnwire/node_announcement.go

@@ -3,11 +3,12 @@ package lnwire
 import (
 	"bytes"
 	"fmt"
+	"io"
+	"net"
+
 	"github.com/go-errors/errors"
 	"github.com/roasbeef/btcd/btcec"
 	"github.com/roasbeef/btcd/wire"
-	"io"
-	"net"
 )
 
 var (
@@ -72,7 +73,7 @@ type NodeAnnouncement struct {
 	// the node is accepting incoming connections.
 	Address *net.TCPAddr
 
-	// NodeID is a public key which is used as node identificator.
+	// NodeID is a public key which is used as node identification.
 	NodeID *btcec.PublicKey
 
 	// RGBColor is used to customize their node's appearance in maps and graphs