wire: add bitcoin network magic for default SigNet

Added constant wire.SigNet, added it to stringer for BitcoinNet type.
Added a test in chaincfg to compare calculated magic value with the constant.

chaincfg/params_test.go

@@ -9,6 +9,9 @@ import (
 	"encoding/hex"
 	"math/big"
 	"testing"
+
+	"github.com/btcsuite/btcd/wire"
+	"github.com/stretchr/testify/require"
 )
 
 // TestInvalidHashStr ensures the newShaHashFromStr function panics when used to
@@ -104,6 +107,12 @@ func TestSigNetPowLimit(t *testing.T) {
 	}
 }
 
+// TestSigNetMagic makes sure that the default signet has the expected bitcoin
+// network magic.
+func TestSigNetMagic(t *testing.T) {
+	require.Equal(t, wire.SigNet, SigNetParams.Net)
+}
+
 // compactToBig is a copy of the blockchain.CompactToBig function. We copy it
 // here so we don't run into a circular dependency just because of a test.
 func compactToBig(compact uint32) *big.Int {

wire/doc.go

@@ -86,6 +86,7 @@ the following constants:
 	wire.MainNet
 	wire.TestNet  (Regression test network)
 	wire.TestNet3 (Test network version 3)
+	wire.SigNet   (Signet, default)
 	wire.SimNet   (Simulation test network)
 
 # Determining Message Type

wire/protocol.go

@@ -169,7 +169,7 @@ func (f ServiceFlag) String() string {
 // BitcoinNet represents which bitcoin network a message belongs to.
 type BitcoinNet uint32
 
-// Constants used to indicate the message bitcoin network.  They can also be
+// Constants used to indicate the message bitcoin network. They can also be
 // used to seek to the next message when a stream's state is unknown, but
 // this package does not provide that functionality since it's generally a
 // better idea to simply disconnect clients that are misbehaving over TCP.
@@ -183,6 +183,10 @@ const (
 	// TestNet3 represents the test network (version 3).
 	TestNet3 BitcoinNet = 0x0709110b
 
+	// SigNet represents the public default SigNet. For custom signets,
+	// see CustomSignetParams.
+	SigNet BitcoinNet = 0x40CF030A
+
 	// SimNet represents the simulation test network.
 	SimNet BitcoinNet = 0x12141c16
 )
@@ -193,6 +197,7 @@ var bnStrings = map[BitcoinNet]string{
 	MainNet:  "MainNet",
 	TestNet:  "TestNet",
 	TestNet3: "TestNet3",
+	SigNet:   "SigNet",
 	SimNet:   "SimNet",
 }
 

wire/protocol_test.go

@@ -49,6 +49,7 @@ func TestBitcoinNetStringer(t *testing.T) {
 		{MainNet, "MainNet"},
 		{TestNet, "TestNet"},
 		{TestNet3, "TestNet3"},
+		{SigNet, "SigNet"},
 		{SimNet, "SimNet"},
 		{0xffffffff, "Unknown BitcoinNet (4294967295)"},
 	}