5f971e10e6
Several of the messages store the parts that have a variable number of elements as slices. This commit modifies the code to choose sane defaults for the backing arrays for the slices so when the entries are actually appended, a lot of the overhead of growing the backing arrays and copying the data multiple times is avoided. Along the same lines, when decoding messages, the actual size is known and now is pre-allocated instead of dynamically growing the backing array thereby avoiding some overhead.
143 lines
4.1 KiB
Go
143 lines
4.1 KiB
Go
// Copyright (c) 2013 Conformal Systems LLC.
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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 btcwire
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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) 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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msg.AddrList = make([]*NetAddress, 0, count)
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for i := uint64(0); i < count; i++ {
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na := NetAddress{}
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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) 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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