github.com/jimmyx0x/go-ethereum@v1.10.28/p2p/discover/common.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 discover
    18  
    19  import (
    20  	"crypto/ecdsa"
    21  	"net"
    22  
    23  	"github.com/ethereum/go-ethereum/common/mclock"
    24  	"github.com/ethereum/go-ethereum/log"
    25  	"github.com/ethereum/go-ethereum/p2p/enode"
    26  	"github.com/ethereum/go-ethereum/p2p/enr"
    27  	"github.com/ethereum/go-ethereum/p2p/netutil"
    28  )
    29  
    30  // UDPConn is a network connection on which discovery can operate.
    31  type UDPConn interface {
    32  	ReadFromUDP(b []byte) (n int, addr *net.UDPAddr, err error)
    33  	WriteToUDP(b []byte, addr *net.UDPAddr) (n int, err error)
    34  	Close() error
    35  	LocalAddr() net.Addr
    36  }
    37  
    38  type V5Config struct {
    39  	ProtocolID *[6]byte
    40  }
    41  
    42  // Config holds settings for the discovery listener.
    43  type Config struct {
    44  	// These settings are required and configure the UDP listener:
    45  	PrivateKey *ecdsa.PrivateKey
    46  
    47  	// These settings are optional:
    48  	NetRestrict *netutil.Netlist  // list of allowed IP networks
    49  	Bootnodes   []*enode.Node     // list of bootstrap nodes
    50  	Unhandled   chan<- ReadPacket // unhandled packets are sent on this channel
    51  	Log         log.Logger        // if set, log messages go here
    52  
    53  	// V5ProtocolID configures the discv5 protocol identifier.
    54  	V5ProtocolID *[6]byte
    55  
    56  	ValidSchemes enr.IdentityScheme // allowed identity schemes
    57  	Clock        mclock.Clock
    58  }
    59  
    60  func (cfg Config) withDefaults() Config {
    61  	if cfg.Log == nil {
    62  		cfg.Log = log.Root()
    63  	}
    64  	if cfg.ValidSchemes == nil {
    65  		cfg.ValidSchemes = enode.ValidSchemes
    66  	}
    67  	if cfg.Clock == nil {
    68  		cfg.Clock = mclock.System{}
    69  	}
    70  	return cfg
    71  }
    72  
    73  // ListenUDP starts listening for discovery packets on the given UDP socket.
    74  func ListenUDP(c UDPConn, ln *enode.LocalNode, cfg Config) (*UDPv4, error) {
    75  	return ListenV4(c, ln, cfg)
    76  }
    77  
    78  // ReadPacket is a packet that couldn't be handled. Those packets are sent to the unhandled
    79  // channel if configured.
    80  type ReadPacket struct {
    81  	Data []byte
    82  	Addr *net.UDPAddr
    83  }
    84  
    85  func min(x, y int) int {
    86  	if x > y {
    87  		return y
    88  	}
    89  	return x
    90  }