66 lines
2.1 KiB
Go
66 lines
2.1 KiB
Go
// Copyright 2020 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 eth
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import (
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"github.com/ethereum/go-ethereum/core"
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"github.com/ethereum/go-ethereum/core/forkid"
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"github.com/ethereum/go-ethereum/p2p/enode"
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"github.com/ethereum/go-ethereum/rlp"
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)
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// enrEntry is the ENR entry which advertises `eth` protocol on the discovery.
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type enrEntry struct {
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ForkID forkid.ID // Fork identifier per EIP-2124
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// Ignore additional fields (for forward compatibility).
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Rest []rlp.RawValue `rlp:"tail"`
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}
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// ENRKey implements enr.Entry.
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func (e enrEntry) ENRKey() string {
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return "eth"
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}
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// StartENRUpdater starts the `eth` ENR updater loop, which listens for chain
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// head events and updates the requested node record whenever a fork is passed.
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func StartENRUpdater(chain *core.BlockChain, ln *enode.LocalNode) {
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var newHead = make(chan core.ChainHeadEvent, 10)
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sub := chain.SubscribeChainHeadEvent(newHead)
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go func() {
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defer sub.Unsubscribe()
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for {
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select {
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case <-newHead:
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ln.Set(currentENREntry(chain))
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case <-sub.Err():
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// Would be nice to sync with Stop, but there is no
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// good way to do that.
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return
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}
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}
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}()
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}
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// currentENREntry constructs an `eth` ENR entry based on the current state of the chain.
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func currentENREntry(chain *core.BlockChain) *enrEntry {
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return &enrEntry{
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ForkID: forkid.NewID(chain.Config(), chain.Genesis().Hash(), chain.CurrentHeader().Number.Uint64()),
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}
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}
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