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msgcftypes.go
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msgcftypes.go
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// Copyright (c) 2017 The btcsuite developers
// Copyright (c) 2017 The Lightning Network Developers
// Copyright (c) 2018 The Decred developers
// Use of this source code is governed by an ISC
// license that can be found in the LICENSE file.
package wire
import (
"fmt"
"io"
)
// MaxFilterTypesPerMsg is the maximum number of filter types allowed per
// message.
const MaxFilterTypesPerMsg = 256
// FilterType is used to represent a filter type.
type FilterType uint8
const (
// GCSFilterRegular is the regular filter type.
GCSFilterRegular FilterType = iota
// GCSFilterExtended is the extended filter type.
GCSFilterExtended
)
// MsgCFTypes is the cftypes message.
type MsgCFTypes struct {
SupportedFilters []FilterType
}
// BtcDecode decodes r using the wire protocol encoding into the receiver.
// This is part of the Message interface implementation.
func (msg *MsgCFTypes) BtcDecode(r io.Reader, pver uint32) error {
if pver < NodeCFVersion {
str := fmt.Sprintf("cftypes message invalid for protocol "+
"version %d", pver)
return messageError("MsgCFTypes.BtcDecode", str)
}
// Read the number of filter types supported. The count may not exceed the
// total number of filters that can be represented by a FilterType byte.
count, err := ReadVarInt(r, pver)
if err != nil {
return err
}
if count > MaxFilterTypesPerMsg {
str := fmt.Sprintf("too many filter types for for message "+
"[count %v, max %v]", count, MaxFilterTypesPerMsg)
return messageError("MsgCFTypes.BtcDecode", str)
}
// Read each filter type.
msg.SupportedFilters = make([]FilterType, count)
for i := range msg.SupportedFilters {
err = readElement(r, (*uint8)(&msg.SupportedFilters[i]))
if err != nil {
return err
}
}
return nil
}
// BtcEncode encodes the receiver to w using the wire protocol encoding. This is
// part of the Message interface implementation.
func (msg *MsgCFTypes) BtcEncode(w io.Writer, pver uint32) error {
if pver < NodeCFVersion {
str := fmt.Sprintf("cftypes message invalid for protocol "+
"version %d", pver)
return messageError("MsgCFTypes.BtcEncode", str)
}
// Write length of supported filters slice. We assume it's deduplicated.
err := WriteVarInt(w, pver, uint64(len(msg.SupportedFilters)))
if err != nil {
return err
}
for i := range msg.SupportedFilters {
err = binarySerializer.PutUint8(w, uint8(msg.SupportedFilters[i]))
if err != nil {
return err
}
}
return nil
}
// Deserialize decodes a filter from r into the receiver using a format that is
// suitable for long-term storage such as a database. This function differs from
// BtcDecode in that BtcDecode decodes from the wire protocol as it was sent
// across the network. The wire encoding can technically differ depending on
// the protocol version and doesn't even really need to match the format of a
// stored filter at all. As of the time this comment was written, the encoded
// filter is the same in both instances, but there is a distinct difference and
// separating the two allows the API to be flexible enough to deal with changes.
func (msg *MsgCFTypes) Deserialize(r io.Reader) error {
// At the current time, there is no difference between the wire encoding
// and the stable long-term storage format. As a result, make use of
// BtcDecode.
return msg.BtcDecode(r, 0)
}
// Command returns the protocol command string for the message. This is part
// of the Message interface implementation.
func (msg *MsgCFTypes) Command() string {
return CmdCFTypes
}
// MaxPayloadLength returns the maximum length the payload can be for the
// receiver. This is part of the Message interface implementation.
func (msg *MsgCFTypes) MaxPayloadLength(pver uint32) uint32 {
// 2 bytes for filter count, and 1 byte for up to 256 filter types.
return 258
}
// NewMsgCFTypes returns a new cftypes message that conforms to the Message
// interface. See MsgCFTypes for details.
func NewMsgCFTypes(filterTypes []FilterType) *MsgCFTypes {
return &MsgCFTypes{
SupportedFilters: filterTypes,
}
}