github.com/unicornultrafoundation/go-u2u@v1.0.0-rc1.0.20240205080301-e74a83d3fadc/gossip/discover.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 gossip
    18  
    19  import (
    20  	"github.com/unicornultrafoundation/go-u2u/common"
    21  	"github.com/unicornultrafoundation/go-u2u/core/forkid"
    22  	"github.com/unicornultrafoundation/go-u2u/p2p/enode"
    23  	"github.com/unicornultrafoundation/go-u2u/rlp"
    24  
    25  	"github.com/unicornultrafoundation/go-u2u/evmcore"
    26  )
    27  
    28  // enrEntry is the ENR entry which advertises `eth` protocol on the discovery.
    29  type enrEntry 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 enrEntry) ENRKey() string {
    38  	return "u2u"
    39  }
    40  
    41  // StartENRUpdater starts the `u2u` ENR updater loop, which listens for chain
    42  // head events and updates the requested node record whenever a fork is passed.
    43  func StartENRUpdater(svc *Service, ln *enode.LocalNode) {
    44  	var newHead = make(chan evmcore.ChainHeadNotify, 10)
    45  	sub := svc.feed.SubscribeNewBlock(newHead)
    46  
    47  	go func() {
    48  		defer sub.Unsubscribe()
    49  		for {
    50  			select {
    51  			case <-newHead:
    52  				ln.Set(currentENREntry(svc))
    53  			case <-sub.Err():
    54  				// Would be nice to sync with Stop, but there is no
    55  				// good way to do that.
    56  				return
    57  			}
    58  		}
    59  	}()
    60  }
    61  
    62  // currentENREntry constructs an `eth` ENR entry based on the current state of the chain.
    63  func currentENREntry(svc *Service) *enrEntry {
    64  	genesisHash := *svc.store.GetGenesisID()
    65  	return &enrEntry{
    66  		ForkID: forkid.NewID(svc.store.GetEvmChainConfig(), common.Hash(genesisHash), uint64(svc.store.GetLatestBlockIndex())),
    67  	}
    68  }