144 lines
4.2 KiB
Go
144 lines
4.2 KiB
Go
// Copyright (c) 2013-2015 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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)
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// MaxAddrPerMsg is the maximum number of addresses that can be in a single
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// bitcoin addr message (MsgAddr).
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const MaxAddrPerMsg = 1000
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// MsgAddr implements the Message interface and represents a bitcoin
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// addr message. It is used to provide a list of known active peers on the
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// network. An active peer is considered one that has transmitted a message
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// within the last 3 hours. Nodes which have not transmitted in that time
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// frame should be forgotten. Each message is limited to a maximum number of
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// addresses, which is currently 1000. As a result, multiple messages must
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// be used to relay the full list.
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//
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// Use the AddAddress function to build up the list of known addresses when
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// sending an addr message to another peer.
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type MsgAddr struct {
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AddrList []*NetAddress
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}
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// AddAddress adds a known active peer to the message.
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func (msg *MsgAddr) AddAddress(na *NetAddress) error {
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if len(msg.AddrList)+1 > MaxAddrPerMsg {
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str := fmt.Sprintf("too many addresses in message [max %v]",
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MaxAddrPerMsg)
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return messageError("MsgAddr.AddAddress", str)
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}
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msg.AddrList = append(msg.AddrList, na)
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return nil
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}
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// AddAddresses adds multiple known active peers to the message.
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func (msg *MsgAddr) AddAddresses(netAddrs ...*NetAddress) error {
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for _, na := range netAddrs {
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err := msg.AddAddress(na)
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if err != nil {
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return err
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}
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}
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return nil
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}
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// ClearAddresses removes all addresses from the message.
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func (msg *MsgAddr) ClearAddresses() {
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msg.AddrList = []*NetAddress{}
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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 *MsgAddr) BtcDecode(r io.Reader, pver uint32, enc MessageEncoding) error {
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count, err := ReadVarInt(r, pver)
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if err != nil {
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return err
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}
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// Limit to max addresses per message.
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if count > MaxAddrPerMsg {
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str := fmt.Sprintf("too many addresses for message "+
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"[count %v, max %v]", count, MaxAddrPerMsg)
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return messageError("MsgAddr.BtcDecode", str)
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}
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addrList := make([]NetAddress, count)
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msg.AddrList = make([]*NetAddress, 0, count)
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for i := uint64(0); i < count; i++ {
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na := &addrList[i]
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err := readNetAddress(r, pver, na, true)
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if err != nil {
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return err
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}
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msg.AddAddress(na)
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}
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return nil
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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 *MsgAddr) BtcEncode(w io.Writer, pver uint32, enc MessageEncoding) error {
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// Protocol versions before MultipleAddressVersion only allowed 1 address
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// per message.
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count := len(msg.AddrList)
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if pver < MultipleAddressVersion && count > 1 {
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str := fmt.Sprintf("too many addresses for message of "+
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"protocol version %v [count %v, max 1]", pver, count)
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return messageError("MsgAddr.BtcEncode", str)
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}
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if count > MaxAddrPerMsg {
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str := fmt.Sprintf("too many addresses for message "+
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"[count %v, max %v]", count, MaxAddrPerMsg)
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return messageError("MsgAddr.BtcEncode", str)
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}
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err := WriteVarInt(w, pver, uint64(count))
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if err != nil {
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return err
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}
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for _, na := range msg.AddrList {
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err = writeNetAddress(w, pver, na, true)
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if err != nil {
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return err
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}
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}
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return nil
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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 *MsgAddr) Command() string {
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return CmdAddr
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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 *MsgAddr) MaxPayloadLength(pver uint32) uint32 {
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if pver < MultipleAddressVersion {
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// Num addresses (varInt) + a single net addresses.
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return MaxVarIntPayload + maxNetAddressPayload(pver)
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}
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// Num addresses (varInt) + max allowed addresses.
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return MaxVarIntPayload + (MaxAddrPerMsg * maxNetAddressPayload(pver))
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}
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// NewMsgAddr returns a new bitcoin addr message that conforms to the
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// Message interface. See MsgAddr for details.
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func NewMsgAddr() *MsgAddr {
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return &MsgAddr{
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AddrList: make([]*NetAddress, 0, MaxAddrPerMsg),
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}
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}
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