github.com/kisexp/xdchain@v0.0.0-20211206025815-490d6b732aa7/eth/discovery.go (about) 1 // Copyright 2019 The go-ethereum Authors 2 // This file is part of the go-ethereum library. 3 // 4 // The go-ethereum library is free software: you can redistribute it and/or modify 5 // it under the terms of the GNU Lesser General Public License as published by 6 // the Free Software Foundation, either version 3 of the License, or 7 // (at your option) any later version. 8 // 9 // The go-ethereum library is distributed in the hope that it will be useful, 10 // but WITHOUT ANY WARRANTY; without even the implied warranty of 11 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 // GNU Lesser General Public License for more details. 13 // 14 // You should have received a copy of the GNU Lesser General Public License 15 // along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>. 16 17 package eth 18 19 import ( 20 "github.com/kisexp/xdchain/core" 21 "github.com/kisexp/xdchain/core/forkid" 22 "github.com/kisexp/xdchain/p2p/dnsdisc" 23 "github.com/kisexp/xdchain/p2p/enode" 24 "github.com/kisexp/xdchain/rlp" 25 ) 26 27 // ethEntry is the "eth" ENR entry which advertises eth protocol 28 // on the discovery network. 29 type ethEntry struct { 30 ForkID forkid.ID // Fork identifier per EIP-2124 31 32 // Ignore additional fields (for forward compatibility). 33 Rest []rlp.RawValue `rlp:"tail"` 34 } 35 36 // ENRKey implements enr.Entry. 37 func (e ethEntry) ENRKey() string { 38 return "eth" 39 } 40 41 // startEthEntryUpdate starts the ENR updater loop. 42 func (eth *Ethereum) startEthEntryUpdate(ln *enode.LocalNode) { 43 var newHead = make(chan core.ChainHeadEvent, 10) 44 sub := eth.blockchain.SubscribeChainHeadEvent(newHead) 45 46 go func() { 47 defer sub.Unsubscribe() 48 for { 49 select { 50 case <-newHead: 51 ln.Set(eth.currentEthEntry()) 52 case <-sub.Err(): 53 // Would be nice to sync with eth.Stop, but there is no 54 // good way to do that. 55 return 56 } 57 } 58 }() 59 } 60 61 func (eth *Ethereum) currentEthEntry() *ethEntry { 62 return ðEntry{ForkID: forkid.NewID(eth.blockchain.Config(), eth.blockchain.Genesis().Hash(), 63 eth.blockchain.CurrentHeader().Number.Uint64())} 64 } 65 66 // setupDiscovery creates the node discovery source for the eth protocol. 67 func (eth *Ethereum) setupDiscovery() (enode.Iterator, error) { 68 if len(eth.config.DiscoveryURLs) == 0 { 69 return nil, nil 70 } 71 client := dnsdisc.NewClient(dnsdisc.Config{}) 72 return client.NewIterator(eth.config.DiscoveryURLs...) 73 }