github.com/openethereum/go-ethereum@v1.9.7/eth/enr_entry.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/ethereum/go-ethereum/core"
    21  	"github.com/ethereum/go-ethereum/core/forkid"
    22  	"github.com/ethereum/go-ethereum/p2p/enode"
    23  	"github.com/ethereum/go-ethereum/rlp"
    24  )
    25  
    26  // ethEntry is the "eth" ENR entry which advertises eth protocol
    27  // on the discovery network.
    28  type ethEntry struct {
    29  	ForkID forkid.ID // Fork identifier per EIP-2124
    30  
    31  	// Ignore additional fields (for forward compatibility).
    32  	Rest []rlp.RawValue `rlp:"tail"`
    33  }
    34  
    35  // ENRKey implements enr.Entry.
    36  func (e ethEntry) ENRKey() string {
    37  	return "eth"
    38  }
    39  
    40  func (eth *Ethereum) startEthEntryUpdate(ln *enode.LocalNode) {
    41  	var newHead = make(chan core.ChainHeadEvent, 10)
    42  	sub := eth.blockchain.SubscribeChainHeadEvent(newHead)
    43  
    44  	go func() {
    45  		defer sub.Unsubscribe()
    46  		for {
    47  			select {
    48  			case <-newHead:
    49  				ln.Set(eth.currentEthEntry())
    50  			case <-sub.Err():
    51  				// Would be nice to sync with eth.Stop, but there is no
    52  				// good way to do that.
    53  				return
    54  			}
    55  		}
    56  	}()
    57  }
    58  
    59  func (eth *Ethereum) currentEthEntry() *ethEntry {
    60  	return &ethEntry{ForkID: forkid.NewID(eth.blockchain)}
    61  }