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