Official Go implementation of the Ethereum protocol
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go-ethereum/p2p/discover/common.go

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3.8 KiB

// Copyright 2019 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
package discover
import (
"crypto/ecdsa"
crand "crypto/rand"
"encoding/binary"
"math/rand"
"net"
"net/netip"
"sync"
"time"
"github.com/ethereum/go-ethereum/common/mclock"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/p2p/enode"
"github.com/ethereum/go-ethereum/p2p/enr"
"github.com/ethereum/go-ethereum/p2p/netutil"
)
// UDPConn is a network connection on which discovery can operate.
type UDPConn interface {
ReadFromUDPAddrPort(b []byte) (n int, addr netip.AddrPort, err error)
WriteToUDPAddrPort(b []byte, addr netip.AddrPort) (n int, err error)
Close() error
LocalAddr() net.Addr
}
// Config holds settings for the discovery listener.
type Config struct {
// These settings are required and configure the UDP listener:
PrivateKey *ecdsa.PrivateKey
// All remaining settings are optional.
// Packet handling configuration:
NetRestrict *netutil.Netlist // list of allowed IP networks
Unhandled chan<- ReadPacket // unhandled packets are sent on this channel
// Node table configuration:
Bootnodes []*enode.Node // list of bootstrap nodes
PingInterval time.Duration // speed of node liveness check
RefreshInterval time.Duration // used in bucket refresh
// The options below are useful in very specific cases, like in unit tests.
V5ProtocolID *[6]byte
Log log.Logger // if set, log messages go here
ValidSchemes enr.IdentityScheme // allowed identity schemes
Clock mclock.Clock
}
func (cfg Config) withDefaults() Config {
// Node table configuration:
if cfg.PingInterval == 0 {
cfg.PingInterval = 3 * time.Second
}
if cfg.RefreshInterval == 0 {
cfg.RefreshInterval = 30 * time.Minute
}
// Debug/test settings:
if cfg.Log == nil {
cfg.Log = log.Root()
}
if cfg.ValidSchemes == nil {
cfg.ValidSchemes = enode.ValidSchemes
}
if cfg.Clock == nil {
cfg.Clock = mclock.System{}
}
return cfg
}
// ListenUDP starts listening for discovery packets on the given UDP socket.
func ListenUDP(c UDPConn, ln *enode.LocalNode, cfg Config) (*UDPv4, error) {
return ListenV4(c, ln, cfg)
}
// ReadPacket is a packet that couldn't be handled. Those packets are sent to the unhandled
// channel if configured.
type ReadPacket struct {
Data []byte
Addr netip.AddrPort
}
type randomSource interface {
Intn(int) int
Int63n(int64) int64
Shuffle(int, func(int, int))
}
// reseedingRandom is a random number generator that tracks when it was last re-seeded.
type reseedingRandom struct {
mu sync.Mutex
cur *rand.Rand
}
func (r *reseedingRandom) seed() {
var b [8]byte
crand.Read(b[:])
seed := binary.BigEndian.Uint64(b[:])
new := rand.New(rand.NewSource(int64(seed)))
r.mu.Lock()
r.cur = new
r.mu.Unlock()
}
func (r *reseedingRandom) Intn(n int) int {
r.mu.Lock()
defer r.mu.Unlock()
return r.cur.Intn(n)
}
func (r *reseedingRandom) Int63n(n int64) int64 {
r.mu.Lock()
defer r.mu.Unlock()
return r.cur.Int63n(n)
}
func (r *reseedingRandom) Shuffle(n int, swap func(i, j int)) {
r.mu.Lock()
defer r.mu.Unlock()
r.cur.Shuffle(n, swap)
}