BIP0144+wire: add a MessageEncoding variant for serialization/deserialization

This commit modifies the existing wire.Message interface to introduce a
new MessageEncoding variant which dictates the exact encoding to be
used when serializing and deserializing messages. Such an option is now
necessary due to the segwit soft-fork package, as btcd will need to be
able to optionally encode transactions/blocks without witness data to
un-upgraded peers.

Two new functions have been introduced: ReadMessageWithEncodingN and
WriteMessageWithEncodingN which wrap BtcDecode/BtcEncode with the
desired encoding format.

wire/msgnotfound_test.go

@@ -104,10 +104,11 @@ func TestNotFoundWire(t *testing.T) {
 	}
 
 	tests := []struct {
-		in   *MsgNotFound // Message to encode
-		out  *MsgNotFound // Expected decoded message
-		buf  []byte       // Wire encoding
-		pver uint32       // Protocol version for wire encoding
+		in   *MsgNotFound    // Message to encode
+		out  *MsgNotFound    // Expected decoded message
+		buf  []byte          // Wire encoding
+		pver uint32          // Protocol version for wire encoding
+		enc  MessageEncoding // Message encoding format
 	}{
 		// Latest protocol version with no inv vectors.
 		{
@@ -115,6 +116,7 @@ func TestNotFoundWire(t *testing.T) {
 			NoInv,
 			NoInvEncoded,
 			ProtocolVersion,
+			BaseEncoding,
 		},
 
 		// Latest protocol version with multiple inv vectors.
@@ -123,6 +125,7 @@ func TestNotFoundWire(t *testing.T) {
 			MultiInv,
 			MultiInvEncoded,
 			ProtocolVersion,
+			BaseEncoding,
 		},
 
 		// Protocol version BIP0035Version no inv vectors.
@@ -131,6 +134,7 @@ func TestNotFoundWire(t *testing.T) {
 			NoInv,
 			NoInvEncoded,
 			BIP0035Version,
+			BaseEncoding,
 		},
 
 		// Protocol version BIP0035Version with multiple inv vectors.
@@ -139,6 +143,7 @@ func TestNotFoundWire(t *testing.T) {
 			MultiInv,
 			MultiInvEncoded,
 			BIP0035Version,
+			BaseEncoding,
 		},
 
 		// Protocol version BIP0031Version no inv vectors.
@@ -147,6 +152,7 @@ func TestNotFoundWire(t *testing.T) {
 			NoInv,
 			NoInvEncoded,
 			BIP0031Version,
+			BaseEncoding,
 		},
 
 		// Protocol version BIP0031Version with multiple inv vectors.
@@ -155,6 +161,7 @@ func TestNotFoundWire(t *testing.T) {
 			MultiInv,
 			MultiInvEncoded,
 			BIP0031Version,
+			BaseEncoding,
 		},
 
 		// Protocol version NetAddressTimeVersion no inv vectors.
@@ -163,6 +170,7 @@ func TestNotFoundWire(t *testing.T) {
 			NoInv,
 			NoInvEncoded,
 			NetAddressTimeVersion,
+			BaseEncoding,
 		},
 
 		// Protocol version NetAddressTimeVersion with multiple inv vectors.
@@ -171,6 +179,7 @@ func TestNotFoundWire(t *testing.T) {
 			MultiInv,
 			MultiInvEncoded,
 			NetAddressTimeVersion,
+			BaseEncoding,
 		},
 
 		// Protocol version MultipleAddressVersion no inv vectors.
@@ -179,6 +188,7 @@ func TestNotFoundWire(t *testing.T) {
 			NoInv,
 			NoInvEncoded,
 			MultipleAddressVersion,
+			BaseEncoding,
 		},
 
 		// Protocol version MultipleAddressVersion with multiple inv vectors.
@@ -187,6 +197,7 @@ func TestNotFoundWire(t *testing.T) {
 			MultiInv,
 			MultiInvEncoded,
 			MultipleAddressVersion,
+			BaseEncoding,
 		},
 	}
 
@@ -194,7 +205,7 @@ func TestNotFoundWire(t *testing.T) {
 	for i, test := range tests {
 		// Encode the message to wire format.
 		var buf bytes.Buffer
-		err := test.in.BtcEncode(&buf, test.pver)
+		err := test.in.BtcEncode(&buf, test.pver, test.enc)
 		if err != nil {
 			t.Errorf("BtcEncode #%d error %v", i, err)
 			continue
@@ -208,7 +219,7 @@ func TestNotFoundWire(t *testing.T) {
 		// Decode the message from wire format.
 		var msg MsgNotFound
 		rbuf := bytes.NewReader(test.buf)
-		err = msg.BtcDecode(rbuf, test.pver)
+		err = msg.BtcDecode(rbuf, test.pver, test.enc)
 		if err != nil {
 			t.Errorf("BtcDecode #%d error %v", i, err)
 			continue
@@ -260,26 +271,27 @@ func TestNotFoundWireErrors(t *testing.T) {
 	}
 
 	tests := []struct {
-		in       *MsgNotFound // Value to encode
-		buf      []byte       // Wire encoding
-		pver     uint32       // Protocol version for wire encoding
-		max      int          // Max size of fixed buffer to induce errors
-		writeErr error        // Expected write error
-		readErr  error        // Expected read error
+		in       *MsgNotFound    // Value to encode
+		buf      []byte          // Wire encoding
+		pver     uint32          // Protocol version for wire encoding
+		enc      MessageEncoding // Message encoding format
+		max      int             // Max size of fixed buffer to induce errors
+		writeErr error           // Expected write error
+		readErr  error           // Expected read error
 	}{
 		// Force error in inventory vector count
-		{baseNotFound, baseNotFoundEncoded, pver, 0, io.ErrShortWrite, io.EOF},
+		{baseNotFound, baseNotFoundEncoded, pver, BaseEncoding, 0, io.ErrShortWrite, io.EOF},
 		// Force error in inventory list.
-		{baseNotFound, baseNotFoundEncoded, pver, 1, io.ErrShortWrite, io.EOF},
+		{baseNotFound, baseNotFoundEncoded, pver, BaseEncoding, 1, io.ErrShortWrite, io.EOF},
 		// Force error with greater than max inventory vectors.
-		{maxNotFound, maxNotFoundEncoded, pver, 3, wireErr, wireErr},
+		{maxNotFound, maxNotFoundEncoded, pver, BaseEncoding, 3, wireErr, wireErr},
 	}
 
 	t.Logf("Running %d tests", len(tests))
 	for i, test := range tests {
 		// Encode to wire format.
 		w := newFixedWriter(test.max)
-		err := test.in.BtcEncode(w, test.pver)
+		err := test.in.BtcEncode(w, test.pver, test.enc)
 		if reflect.TypeOf(err) != reflect.TypeOf(test.writeErr) {
 			t.Errorf("BtcEncode #%d wrong error got: %v, want: %v",
 				i, err, test.writeErr)
@@ -299,7 +311,7 @@ func TestNotFoundWireErrors(t *testing.T) {
 		// Decode from wire format.
 		var msg MsgNotFound
 		r := newFixedReader(test.max, test.buf)
-		err = msg.BtcDecode(r, test.pver)
+		err = msg.BtcDecode(r, test.pver, test.enc)
 		if reflect.TypeOf(err) != reflect.TypeOf(test.readErr) {
 			t.Errorf("BtcDecode #%d wrong error got: %v, want: %v",
 				i, err, test.readErr)