83 lines
2.3 KiB
Go
83 lines
2.3 KiB
Go
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// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package diff
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import (
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"fmt"
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"time"
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"github.com/ethereum/go-ethereum/common/gopool"
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"github.com/ethereum/go-ethereum/p2p"
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)
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const (
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// handshakeTimeout is the maximum allowed time for the `diff` handshake to
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// complete before dropping the connection.= as malicious.
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handshakeTimeout = 5 * time.Second
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)
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// Handshake executes the diff protocol handshake,
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func (p *Peer) Handshake(diffSync bool) error {
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// Send out own handshake in a new thread
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errc := make(chan error, 2)
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var cap DiffCapPacket // safe to read after two values have been received from errc
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gopool.Submit(func() {
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errc <- p2p.Send(p.rw, DiffCapMsg, &DiffCapPacket{
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DiffSync: diffSync,
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Extra: defaultExtra,
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})
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})
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gopool.Submit(func() {
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errc <- p.readCap(&cap)
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})
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timeout := time.NewTimer(handshakeTimeout)
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defer timeout.Stop()
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for i := 0; i < 2; i++ {
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select {
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case err := <-errc:
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if err != nil {
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return err
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}
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case <-timeout.C:
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return p2p.DiscReadTimeout
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}
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}
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p.diffSync = cap.DiffSync
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return nil
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}
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// readStatus reads the remote handshake message.
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func (p *Peer) readCap(cap *DiffCapPacket) error {
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msg, err := p.rw.ReadMsg()
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if err != nil {
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return err
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}
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if msg.Code != DiffCapMsg {
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return fmt.Errorf("%w: first msg has code %x (!= %x)", errNoCapMsg, msg.Code, DiffCapMsg)
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}
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if msg.Size > maxMessageSize {
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return fmt.Errorf("%w: %v > %v", errMsgTooLarge, msg.Size, maxMessageSize)
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}
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// Decode the handshake and make sure everything matches
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if err := msg.Decode(cap); err != nil {
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return fmt.Errorf("%w: message %v: %v", errDecode, msg, err)
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}
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return nil
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}
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