wire: update messages to conform to BIP and fix comments

wire/message_test.go

@@ -105,7 +105,7 @@ func TestMessage(t *testing.T) {
 		{msgMerkleBlock, msgMerkleBlock, pver, MainNet, 110},
 		{msgReject, msgReject, pver, MainNet, 79},
 		{msgGetCFilter, msgGetCFilter, pver, MainNet, 57},
-		{msgGetCFHeaders, msgGetCFHeaders, pver, MainNet, 62},
+		{msgGetCFHeaders, msgGetCFHeaders, pver, MainNet, 58},
 		{msgGetCFTypes, msgGetCFTypes, pver, MainNet, 24},
 		{msgCFilter, msgCFilter, pver, MainNet, 65},
 		{msgCFHeaders, msgCFHeaders, pver, MainNet, 58},

wire/msgcfheaders.go

@@ -150,9 +150,10 @@ func (msg *MsgCFHeaders) Command() string {
 }
 
 // MaxPayloadLength returns the maximum length the payload can be for the
-// receiver.  This is part of the Message interface implementation.
+// receiver. This is part of the Message interface implementation.
 func (msg *MsgCFHeaders) MaxPayloadLength(pver uint32) uint32 {
-	// Hash size + num headers (varInt) + (header size * max headers).
+	// Hash size + filter type + num headers (varInt) +
+	// (header size * max headers).
 	return chainhash.HashSize + 1 + MaxVarIntPayload +
 		(MaxCFHeaderPayload * MaxCFHeadersPerMsg)
 }

wire/msgcfilter.go

@@ -13,9 +13,13 @@ import (
 
 const (
 	// MaxCFilterDataSize is the maximum byte size of a committed filter.
-	MaxCFilterDataSize = 262144
+	// The maximum size is currently defined as 256KiB.
+	MaxCFilterDataSize = 256 * 1024
 )
 
+// MsgCFilter implements the Message interface and represents a bitcoin cfilter
+// message. It is used to deliver a committed filter in response to a
+// getcfilter (MsgGetCFilter) message.
 type MsgCFilter struct {
 	BlockHash  chainhash.Hash
 	FilterType uint8
@@ -25,9 +29,8 @@ type MsgCFilter struct {
 // BtcDecode decodes r using the bitcoin protocol encoding into the receiver.
 // This is part of the Message interface implementation.
 func (msg *MsgCFilter) BtcDecode(r io.Reader, pver uint32, _ MessageEncoding) error {
-	var err error
 	// Read the hash of the filter's block
-	err = readElement(r, &msg.BlockHash)
+	err := readElement(r, &msg.BlockHash)
 	if err != nil {
 		return err
 	}

wire/msggetcfheaders.go

@@ -15,7 +15,6 @@ import (
 // filter headers. It allows to set the FilterType field to get headers in the
 // chain of basic (0x00) or extended (0x01) headers.
 type MsgGetCFHeaders struct {
-	ProtocolVersion    uint32
 	BlockLocatorHashes []*chainhash.Hash
 	HashStop           chainhash.Hash
 	FilterType         uint8
@@ -36,11 +35,6 @@ func (msg *MsgGetCFHeaders) AddBlockLocatorHash(hash *chainhash.Hash) error {
 // BtcDecode decodes r using the bitcoin protocol encoding into the receiver.
 // This is part of the Message interface implementation.
 func (msg *MsgGetCFHeaders) BtcDecode(r io.Reader, pver uint32, _ MessageEncoding) error {
-	err := readElement(r, &msg.ProtocolVersion)
-	if err != nil {
-		return err
-	}
-
 	// Read num block locator hashes and limit to max.
 	count, err := ReadVarInt(r, pver)
 	if err != nil {
@@ -84,12 +78,7 @@ func (msg *MsgGetCFHeaders) BtcEncode(w io.Writer, pver uint32, _ MessageEncodin
 		return messageError("MsgGetHeaders.BtcEncode", str)
 	}
 
-	err := writeElement(w, msg.ProtocolVersion)
+	err := WriteVarInt(w, pver, uint64(count))
-	if err != nil {
-		return err
-	}
-
-	err = WriteVarInt(w, pver, uint64(count))
 	if err != nil {
 		return err
 	}
@@ -118,9 +107,9 @@ func (msg *MsgGetCFHeaders) Command() string {
 // MaxPayloadLength returns the maximum length the payload can be for the
 // receiver.  This is part of the Message interface implementation.
 func (msg *MsgGetCFHeaders) MaxPayloadLength(pver uint32) uint32 {
-	// Version 4 bytes + num block locator hashes (varInt) + max allowed
+	// Num block locator hashes (varInt) + max allowed
 	// block locators + hash stop + filter type 1 byte.
-	return 4 + MaxVarIntPayload + (MaxBlockLocatorsPerMsg *
+	return MaxVarIntPayload + (MaxBlockLocatorsPerMsg *
 		chainhash.HashSize) + chainhash.HashSize + 1
 }
 

wire/msggetcfilter.go

@@ -10,11 +10,15 @@ import (
 	"github.com/btcsuite/btcd/chaincfg/chainhash"
 )
 
+// MsgGetCFilter implements the Message interface and represents a bitcoin
+// getcfilter message. It is used to request a committed filter for a block.
 type MsgGetCFilter struct {
 	BlockHash  chainhash.Hash
 	FilterType uint8
 }
 
+// BtcDecode decodes r using the bitcoin protocol encoding into the receiver.
+// This is part of the Message interface implementation.
 func (msg *MsgGetCFilter) BtcDecode(r io.Reader, pver uint32, _ MessageEncoding) error {
 	err := readElement(r, &msg.BlockHash)
 	if err != nil {