119 lines
3.7 KiB
Go
119 lines
3.7 KiB
Go
// Copyright (c) 2017 The btcsuite developers
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// Use of this source code is governed by an ISC
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// license that can be found in the LICENSE file.
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package wire
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import (
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"fmt"
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"io"
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"github.com/lbryio/lbcd/chaincfg/chainhash"
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)
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// FilterType is used to represent a filter type.
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type FilterType uint8
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const (
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// GCSFilterRegular is the regular filter type.
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GCSFilterRegular FilterType = iota
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)
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const (
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// MaxCFilterDataSize is the maximum byte size of a committed filter.
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// The maximum size is currently defined as 256KiB.
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MaxCFilterDataSize = 256 * 1024
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)
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// MsgCFilter implements the Message interface and represents a bitcoin cfilter
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// message. It is used to deliver a committed filter in response to a
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// getcfilters (MsgGetCFilters) message.
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type MsgCFilter struct {
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FilterType FilterType
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BlockHash chainhash.Hash
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Data []byte
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}
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// BtcDecode decodes r using the bitcoin protocol encoding into the receiver.
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// This is part of the Message interface implementation.
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func (msg *MsgCFilter) BtcDecode(r io.Reader, pver uint32, _ MessageEncoding) error {
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// Read filter type
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err := readElement(r, &msg.FilterType)
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if err != nil {
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return err
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}
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// Read the hash of the filter's block
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err = readElement(r, &msg.BlockHash)
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if err != nil {
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return err
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}
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// Read filter data
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msg.Data, err = ReadVarBytes(r, pver, MaxCFilterDataSize,
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"cfilter data")
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return err
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}
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// BtcEncode encodes the receiver to w using the bitcoin protocol encoding.
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// This is part of the Message interface implementation.
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func (msg *MsgCFilter) BtcEncode(w io.Writer, pver uint32, _ MessageEncoding) error {
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size := len(msg.Data)
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if size > MaxCFilterDataSize {
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str := fmt.Sprintf("cfilter size too large for message "+
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"[size %v, max %v]", size, MaxCFilterDataSize)
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return messageError("MsgCFilter.BtcEncode", str)
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}
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err := writeElement(w, msg.FilterType)
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if err != nil {
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return err
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}
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err = writeElement(w, msg.BlockHash)
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if err != nil {
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return err
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}
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return WriteVarBytes(w, pver, msg.Data)
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}
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// Deserialize decodes a filter from r into the receiver using a format that is
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// suitable for long-term storage such as a database. This function differs
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// from BtcDecode in that BtcDecode decodes from the bitcoin wire protocol as
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// it was sent across the network. The wire encoding can technically differ
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// depending on the protocol version and doesn't even really need to match the
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// format of a stored filter at all. As of the time this comment was written,
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// the encoded filter is the same in both instances, but there is a distinct
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// difference and separating the two allows the API to be flexible enough to
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// deal with changes.
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func (msg *MsgCFilter) Deserialize(r io.Reader) error {
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// At the current time, there is no difference between the wire encoding
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// and the stable long-term storage format. As a result, make use of
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// BtcDecode.
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return msg.BtcDecode(r, 0, BaseEncoding)
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}
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// Command returns the protocol command string for the message. This is part
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// of the Message interface implementation.
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func (msg *MsgCFilter) Command() string {
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return CmdCFilter
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}
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// MaxPayloadLength returns the maximum length the payload can be for the
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// receiver. This is part of the Message interface implementation.
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func (msg *MsgCFilter) MaxPayloadLength(pver uint32) uint32 {
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return uint32(VarIntSerializeSize(MaxCFilterDataSize)) +
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MaxCFilterDataSize + chainhash.HashSize + 1
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}
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// NewMsgCFilter returns a new bitcoin cfilter message that conforms to the
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// Message interface. See MsgCFilter for details.
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func NewMsgCFilter(filterType FilterType, blockHash *chainhash.Hash,
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data []byte) *MsgCFilter {
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return &MsgCFilter{
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FilterType: filterType,
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BlockHash: *blockHash,
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Data: data,
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}
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}
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