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tendermint/p2p/pex/addrbook.go

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// Modified for Tendermint
// Originally Copyright (c) 2013-2014 Conformal Systems LLC.
// https://github.com/conformal/btcd/blob/master/LICENSE
package pex
import (
"crypto/sha256"
"encoding/binary"
"fmt"
"math"
"math/rand"
"net"
"sync"
"time"
"github.com/tendermint/tendermint/crypto"
cmn "github.com/tendermint/tendermint/libs/common"
"github.com/tendermint/tendermint/p2p"
)
const (
bucketTypeNew = 0x01
bucketTypeOld = 0x02
)
// AddrBook is an address book used for tracking peers
// so we can gossip about them to others and select
// peers to dial.
// TODO: break this up?
type AddrBook interface {
cmn.Service
// Add our own addresses so we don't later add ourselves
AddOurAddress(*p2p.NetAddress)
// Check if it is our address
OurAddress(*p2p.NetAddress) bool
AddPrivateIDs([]string)
// Add and remove an address
AddAddress(addr *p2p.NetAddress, src *p2p.NetAddress) error
RemoveAddress(*p2p.NetAddress)
// Check if the address is in the book
HasAddress(*p2p.NetAddress) bool
// Do we need more peers?
NeedMoreAddrs() bool
// Is Address Book Empty? Answer should not depend on being in your own
// address book, or private peers
Empty() bool
// Pick an address to dial
PickAddress(biasTowardsNewAddrs int) *p2p.NetAddress
// Mark address
MarkGood(p2p.ID)
MarkAttempt(*p2p.NetAddress)
MarkBad(*p2p.NetAddress)
IsGood(*p2p.NetAddress) bool
// Send a selection of addresses to peers
GetSelection() []*p2p.NetAddress
// Send a selection of addresses with bias
GetSelectionWithBias(biasTowardsNewAddrs int) []*p2p.NetAddress
Size() int
// Persist to disk
Save()
}
var _ AddrBook = (*addrBook)(nil)
// addrBook - concurrency safe peer address manager.
// Implements AddrBook.
type addrBook struct {
cmn.BaseService
// immutable after creation
filePath string
routabilityStrict bool
key string // random prefix for bucket placement
// accessed concurrently
mtx sync.Mutex
rand *cmn.Rand
ourAddrs map[string]struct{}
privateIDs map[p2p.ID]struct{}
addrLookup map[p2p.ID]*knownAddress // new & old
bucketsOld []map[string]*knownAddress
bucketsNew []map[string]*knownAddress
nOld int
nNew int
wg sync.WaitGroup
}
// NewAddrBook creates a new address book.
// Use Start to begin processing asynchronous address updates.
func NewAddrBook(filePath string, routabilityStrict bool) *addrBook {
am := &addrBook{
rand: cmn.NewRand(),
ourAddrs: make(map[string]struct{}),
privateIDs: make(map[p2p.ID]struct{}),
addrLookup: make(map[p2p.ID]*knownAddress),
filePath: filePath,
routabilityStrict: routabilityStrict,
}
am.init()
am.BaseService = *cmn.NewBaseService(nil, "AddrBook", am)
return am
}
// Initialize the buckets.
// When modifying this, don't forget to update loadFromFile()
func (a *addrBook) init() {
a.key = crypto.CRandHex(24) // 24/2 * 8 = 96 bits
// New addr buckets
a.bucketsNew = make([]map[string]*knownAddress, newBucketCount)
for i := range a.bucketsNew {
a.bucketsNew[i] = make(map[string]*knownAddress)
}
// Old addr buckets
a.bucketsOld = make([]map[string]*knownAddress, oldBucketCount)
for i := range a.bucketsOld {
a.bucketsOld[i] = make(map[string]*knownAddress)
}
}
// OnStart implements Service.
func (a *addrBook) OnStart() error {
if err := a.BaseService.OnStart(); err != nil {
return err
}
a.loadFromFile(a.filePath)
// wg.Add to ensure that any invocation of .Wait()
// later on will wait for saveRoutine to terminate.
a.wg.Add(1)
go a.saveRoutine()
return nil
}
// OnStop implements Service.
func (a *addrBook) OnStop() {
a.BaseService.OnStop()
}
func (a *addrBook) Wait() {
a.wg.Wait()
}
func (a *addrBook) FilePath() string {
return a.filePath
}
//-------------------------------------------------------
// AddOurAddress one of our addresses.
func (a *addrBook) AddOurAddress(addr *p2p.NetAddress) {
a.mtx.Lock()
defer a.mtx.Unlock()
a.Logger.Info("Add our address to book", "addr", addr)
a.ourAddrs[addr.String()] = struct{}{}
}
// OurAddress returns true if it is our address.
func (a *addrBook) OurAddress(addr *p2p.NetAddress) bool {
a.mtx.Lock()
defer a.mtx.Unlock()
_, ok := a.ourAddrs[addr.String()]
return ok
}
func (a *addrBook) AddPrivateIDs(ids []string) {
a.mtx.Lock()
defer a.mtx.Unlock()
for _, id := range ids {
a.privateIDs[p2p.ID(id)] = struct{}{}
}
}
// AddAddress implements AddrBook
// Add address to a "new" bucket. If it's already in one, only add it probabilistically.
// Returns error if the addr is non-routable. Does not add self.
// NOTE: addr must not be nil
func (a *addrBook) AddAddress(addr *p2p.NetAddress, src *p2p.NetAddress) error {
a.mtx.Lock()
defer a.mtx.Unlock()
return a.addAddress(addr, src)
}
// RemoveAddress implements AddrBook - removes the address from the book.
func (a *addrBook) RemoveAddress(addr *p2p.NetAddress) {
a.mtx.Lock()
defer a.mtx.Unlock()
ka := a.addrLookup[addr.ID]
if ka == nil {
return
}
a.Logger.Info("Remove address from book", "addr", addr)
a.removeFromAllBuckets(ka)
}
// IsGood returns true if peer was ever marked as good and haven't
// done anything wrong since then.
func (a *addrBook) IsGood(addr *p2p.NetAddress) bool {
a.mtx.Lock()
defer a.mtx.Unlock()
return a.addrLookup[addr.ID].isOld()
}
// HasAddress returns true if the address is in the book.
func (a *addrBook) HasAddress(addr *p2p.NetAddress) bool {
a.mtx.Lock()
defer a.mtx.Unlock()
ka := a.addrLookup[addr.ID]
return ka != nil
}
// NeedMoreAddrs implements AddrBook - returns true if there are not have enough addresses in the book.
func (a *addrBook) NeedMoreAddrs() bool {
return a.Size() < needAddressThreshold
}
// Empty implements AddrBook - returns true if there are no addresses in the address book.
// Does not count the peer appearing in its own address book, or private peers.
func (a *addrBook) Empty() bool {
return a.Size() == 0
}
// PickAddress implements AddrBook. It picks an address to connect to.
// The address is picked randomly from an old or new bucket according
// to the biasTowardsNewAddrs argument, which must be between [0, 100] (or else is truncated to that range)
// and determines how biased we are to pick an address from a new bucket.
// PickAddress returns nil if the AddrBook is empty or if we try to pick
// from an empty bucket.
func (a *addrBook) PickAddress(biasTowardsNewAddrs int) *p2p.NetAddress {
a.mtx.Lock()
defer a.mtx.Unlock()
bookSize := a.size()
if bookSize <= 0 {
if bookSize < 0 {
panic(fmt.Sprintf("Addrbook size %d (new: %d + old: %d) is less than 0", a.nNew+a.nOld, a.nNew, a.nOld))
}
return nil
}
if biasTowardsNewAddrs > 100 {
biasTowardsNewAddrs = 100
}
if biasTowardsNewAddrs < 0 {
biasTowardsNewAddrs = 0
}
// Bias between new and old addresses.
oldCorrelation := math.Sqrt(float64(a.nOld)) * (100.0 - float64(biasTowardsNewAddrs))
newCorrelation := math.Sqrt(float64(a.nNew)) * float64(biasTowardsNewAddrs)
// pick a random peer from a random bucket
var bucket map[string]*knownAddress
pickFromOldBucket := (newCorrelation+oldCorrelation)*a.rand.Float64() < oldCorrelation
if (pickFromOldBucket && a.nOld == 0) ||
(!pickFromOldBucket && a.nNew == 0) {
return nil
}
// loop until we pick a random non-empty bucket
for len(bucket) == 0 {
if pickFromOldBucket {
bucket = a.bucketsOld[a.rand.Intn(len(a.bucketsOld))]
} else {
bucket = a.bucketsNew[a.rand.Intn(len(a.bucketsNew))]
}
}
// pick a random index and loop over the map to return that index
randIndex := a.rand.Intn(len(bucket))
for _, ka := range bucket {
if randIndex == 0 {
return ka.Addr
}
randIndex--
}
return nil
}
// MarkGood implements AddrBook - it marks the peer as good and
// moves it into an "old" bucket.
func (a *addrBook) MarkGood(id p2p.ID) {
a.mtx.Lock()
defer a.mtx.Unlock()
ka := a.addrLookup[id]
if ka == nil {
return
}
ka.markGood()
if ka.isNew() {
a.moveToOld(ka)
}
}
// MarkAttempt implements AddrBook - it marks that an attempt was made to connect to the address.
func (a *addrBook) MarkAttempt(addr *p2p.NetAddress) {
a.mtx.Lock()
defer a.mtx.Unlock()
ka := a.addrLookup[addr.ID]
if ka == nil {
return
}
ka.markAttempt()
}
// MarkBad implements AddrBook. Currently it just ejects the address.
// TODO: black list for some amount of time
func (a *addrBook) MarkBad(addr *p2p.NetAddress) {
a.RemoveAddress(addr)
}
// GetSelection implements AddrBook.
// It randomly selects some addresses (old & new). Suitable for peer-exchange protocols.
// Must never return a nil address.
func (a *addrBook) GetSelection() []*p2p.NetAddress {
a.mtx.Lock()
defer a.mtx.Unlock()
bookSize := a.size()
if bookSize <= 0 {
if bookSize < 0 {
panic(fmt.Sprintf("Addrbook size %d (new: %d + old: %d) is less than 0", a.nNew+a.nOld, a.nNew, a.nOld))
}
return nil
}
numAddresses := cmn.MaxInt(
cmn.MinInt(minGetSelection, bookSize),
bookSize*getSelectionPercent/100)
numAddresses = cmn.MinInt(maxGetSelection, numAddresses)
// XXX: instead of making a list of all addresses, shuffling, and slicing a random chunk,
// could we just select a random numAddresses of indexes?
allAddr := make([]*p2p.NetAddress, bookSize)
i := 0
for _, ka := range a.addrLookup {
allAddr[i] = ka.Addr
i++
}
// Fisher-Yates shuffle the array. We only need to do the first
// `numAddresses' since we are throwing the rest.
for i := 0; i < numAddresses; i++ {
// pick a number between current index and the end
j := cmn.RandIntn(len(allAddr)-i) + i
allAddr[i], allAddr[j] = allAddr[j], allAddr[i]
}
// slice off the limit we are willing to share.
return allAddr[:numAddresses]
}
func percentageOfNum(p, n int) int {
return int(math.Round((float64(p) / float64(100)) * float64(n)))
}
// GetSelectionWithBias implements AddrBook.
// It randomly selects some addresses (old & new). Suitable for peer-exchange protocols.
// Must never return a nil address.
//
// Each address is picked randomly from an old or new bucket according to the
// biasTowardsNewAddrs argument, which must be between [0, 100] (or else is truncated to
// that range) and determines how biased we are to pick an address from a new
// bucket.
func (a *addrBook) GetSelectionWithBias(biasTowardsNewAddrs int) []*p2p.NetAddress {
a.mtx.Lock()
defer a.mtx.Unlock()
bookSize := a.size()
if bookSize <= 0 {
if bookSize < 0 {
panic(fmt.Sprintf("Addrbook size %d (new: %d + old: %d) is less than 0", a.nNew+a.nOld, a.nNew, a.nOld))
}
return nil
}
if biasTowardsNewAddrs > 100 {
biasTowardsNewAddrs = 100
}
if biasTowardsNewAddrs < 0 {
biasTowardsNewAddrs = 0
}
numAddresses := cmn.MaxInt(
cmn.MinInt(minGetSelection, bookSize),
bookSize*getSelectionPercent/100)
numAddresses = cmn.MinInt(maxGetSelection, numAddresses)
// number of new addresses that, if possible, should be in the beginning of the selection
// if there are no enough old addrs, will choose new addr instead.
numRequiredNewAdd := cmn.MaxInt(percentageOfNum(biasTowardsNewAddrs, numAddresses), numAddresses-a.nOld)
selection := a.randomPickAddresses(bucketTypeNew, numRequiredNewAdd)
selection = append(selection, a.randomPickAddresses(bucketTypeOld, numAddresses-len(selection))...)
return selection
}
//------------------------------------------------
// Size returns the number of addresses in the book.
func (a *addrBook) Size() int {
a.mtx.Lock()
defer a.mtx.Unlock()
return a.size()
}
func (a *addrBook) size() int {
return a.nNew + a.nOld
}
//----------------------------------------------------------
// Save persists the address book to disk.
func (a *addrBook) Save() {
a.saveToFile(a.filePath) // thread safe
}
func (a *addrBook) saveRoutine() {
defer a.wg.Done()
saveFileTicker := time.NewTicker(dumpAddressInterval)
out:
for {
select {
case <-saveFileTicker.C:
a.saveToFile(a.filePath)
case <-a.Quit():
break out
}
}
saveFileTicker.Stop()
a.saveToFile(a.filePath)
}
//----------------------------------------------------------
func (a *addrBook) getBucket(bucketType byte, bucketIdx int) map[string]*knownAddress {
switch bucketType {
case bucketTypeNew:
return a.bucketsNew[bucketIdx]
case bucketTypeOld:
return a.bucketsOld[bucketIdx]
default:
panic("Invalid bucket type")
}
}
// Adds ka to new bucket. Returns false if it couldn't do it cuz buckets full.
// NOTE: currently it always returns true.
func (a *addrBook) addToNewBucket(ka *knownAddress, bucketIdx int) {
// Sanity check
if ka.isOld() {
a.Logger.Error("Failed Sanity Check! Cant add old address to new bucket", "ka", ka, "bucket", bucketIdx)
return
}
addrStr := ka.Addr.String()
bucket := a.getBucket(bucketTypeNew, bucketIdx)
// Already exists?
if _, ok := bucket[addrStr]; ok {
return
}
// Enforce max addresses.
if len(bucket) > newBucketSize {
a.Logger.Info("new bucket is full, expiring new")
a.expireNew(bucketIdx)
}
// Add to bucket.
bucket[addrStr] = ka
// increment nNew if the peer doesnt already exist in a bucket
if ka.addBucketRef(bucketIdx) == 1 {
a.nNew++
}
// Add it to addrLookup
a.addrLookup[ka.ID()] = ka
}
// Adds ka to old bucket. Returns false if it couldn't do it cuz buckets full.
func (a *addrBook) addToOldBucket(ka *knownAddress, bucketIdx int) bool {
// Sanity check
if ka.isNew() {
a.Logger.Error(fmt.Sprintf("Cannot add new address to old bucket: %v", ka))
return false
}
if len(ka.Buckets) != 0 {
a.Logger.Error(fmt.Sprintf("Cannot add already old address to another old bucket: %v", ka))
return false
}
addrStr := ka.Addr.String()
bucket := a.getBucket(bucketTypeOld, bucketIdx)
// Already exists?
if _, ok := bucket[addrStr]; ok {
return true
}
// Enforce max addresses.
if len(bucket) > oldBucketSize {
return false
}
// Add to bucket.
bucket[addrStr] = ka
if ka.addBucketRef(bucketIdx) == 1 {
a.nOld++
}
// Ensure in addrLookup
a.addrLookup[ka.ID()] = ka
return true
}
func (a *addrBook) removeFromBucket(ka *knownAddress, bucketType byte, bucketIdx int) {
if ka.BucketType != bucketType {
a.Logger.Error(fmt.Sprintf("Bucket type mismatch: %v", ka))
return
}
bucket := a.getBucket(bucketType, bucketIdx)
delete(bucket, ka.Addr.String())
if ka.removeBucketRef(bucketIdx) == 0 {
if bucketType == bucketTypeNew {
a.nNew--
} else {
a.nOld--
}
delete(a.addrLookup, ka.ID())
}
}
func (a *addrBook) removeFromAllBuckets(ka *knownAddress) {
for _, bucketIdx := range ka.Buckets {
bucket := a.getBucket(ka.BucketType, bucketIdx)
delete(bucket, ka.Addr.String())
}
ka.Buckets = nil
if ka.BucketType == bucketTypeNew {
a.nNew--
} else {
a.nOld--
}
delete(a.addrLookup, ka.ID())
}
//----------------------------------------------------------
func (a *addrBook) pickOldest(bucketType byte, bucketIdx int) *knownAddress {
bucket := a.getBucket(bucketType, bucketIdx)
var oldest *knownAddress
for _, ka := range bucket {
if oldest == nil || ka.LastAttempt.Before(oldest.LastAttempt) {
oldest = ka
}
}
return oldest
}
// adds the address to a "new" bucket. if its already in one,
// it only adds it probabilistically
func (a *addrBook) addAddress(addr, src *p2p.NetAddress) error {
if addr == nil || src == nil {
return ErrAddrBookNilAddr{addr, src}
}
if err := addr.Valid(); err != nil {
return ErrAddrBookInvalidAddr{Addr: addr, AddrErr: err}
}
if _, ok := a.privateIDs[addr.ID]; ok {
return ErrAddrBookPrivate{addr}
}
if _, ok := a.privateIDs[src.ID]; ok {
return ErrAddrBookPrivateSrc{src}
}
// TODO: we should track ourAddrs by ID and by IP:PORT and refuse both.
if _, ok := a.ourAddrs[addr.String()]; ok {
return ErrAddrBookSelf{addr}
}
if a.routabilityStrict && !addr.Routable() {
return ErrAddrBookNonRoutable{addr}
}
ka := a.addrLookup[addr.ID]
if ka != nil {
// If its already old and the addr is the same, ignore it.
if ka.isOld() && ka.Addr.Equals(addr) {
return nil
}
// Already in max new buckets.
if len(ka.Buckets) == maxNewBucketsPerAddress {
return nil
}
// The more entries we have, the less likely we are to add more.
factor := int32(2 * len(ka.Buckets))
if a.rand.Int31n(factor) != 0 {
return nil
}
} else {
ka = newKnownAddress(addr, src)
}
bucket := a.calcNewBucket(addr, src)
a.addToNewBucket(ka, bucket)
return nil
}
func (a *addrBook) randomPickAddresses(bucketType byte, num int) []*p2p.NetAddress {
var buckets []map[string]*knownAddress
switch bucketType {
case bucketTypeNew:
buckets = a.bucketsNew
case bucketTypeOld:
buckets = a.bucketsOld
default:
panic("unexpected bucketType")
}
total := 0
for _, bucket := range buckets {
total += len(bucket)
}
addresses := make([]*knownAddress, 0, total)
for _, bucket := range buckets {
for _, ka := range bucket {
addresses = append(addresses, ka)
}
}
selection := make([]*p2p.NetAddress, 0, num)
chosenSet := make(map[string]bool, num)
rand.Shuffle(total, func(i, j int) {
addresses[i], addresses[j] = addresses[j], addresses[i]
})
for _, addr := range addresses {
if chosenSet[addr.Addr.String()] {
continue
}
chosenSet[addr.Addr.String()] = true
selection = append(selection, addr.Addr)
if len(selection) >= num {
return selection
}
}
return selection
}
// Make space in the new buckets by expiring the really bad entries.
// If no bad entries are available we remove the oldest.
func (a *addrBook) expireNew(bucketIdx int) {
for addrStr, ka := range a.bucketsNew[bucketIdx] {
// If an entry is bad, throw it away
if ka.isBad() {
a.Logger.Info(fmt.Sprintf("expiring bad address %v", addrStr))
a.removeFromBucket(ka, bucketTypeNew, bucketIdx)
return
}
}
// If we haven't thrown out a bad entry, throw out the oldest entry
oldest := a.pickOldest(bucketTypeNew, bucketIdx)
a.removeFromBucket(oldest, bucketTypeNew, bucketIdx)
}
// Promotes an address from new to old. If the destination bucket is full,
// demote the oldest one to a "new" bucket.
// TODO: Demote more probabilistically?
func (a *addrBook) moveToOld(ka *knownAddress) {
// Sanity check
if ka.isOld() {
a.Logger.Error(fmt.Sprintf("Cannot promote address that is already old %v", ka))
return
}
if len(ka.Buckets) == 0 {
a.Logger.Error(fmt.Sprintf("Cannot promote address that isn't in any new buckets %v", ka))
return
}
// Remove from all (new) buckets.
a.removeFromAllBuckets(ka)
// It's officially old now.
ka.BucketType = bucketTypeOld
// Try to add it to its oldBucket destination.
oldBucketIdx := a.calcOldBucket(ka.Addr)
added := a.addToOldBucket(ka, oldBucketIdx)
if !added {
// No room; move the oldest to a new bucket
oldest := a.pickOldest(bucketTypeOld, oldBucketIdx)
a.removeFromBucket(oldest, bucketTypeOld, oldBucketIdx)
newBucketIdx := a.calcNewBucket(oldest.Addr, oldest.Src)
a.addToNewBucket(oldest, newBucketIdx)
// Finally, add our ka to old bucket again.
added = a.addToOldBucket(ka, oldBucketIdx)
if !added {
a.Logger.Error(fmt.Sprintf("Could not re-add ka %v to oldBucketIdx %v", ka, oldBucketIdx))
}
}
}
//---------------------------------------------------------------------
// calculate bucket placements
// doublesha256( key + sourcegroup +
// int64(doublesha256(key + group + sourcegroup))%bucket_per_group ) % num_new_buckets
func (a *addrBook) calcNewBucket(addr, src *p2p.NetAddress) int {
data1 := []byte{}
data1 = append(data1, []byte(a.key)...)
data1 = append(data1, []byte(a.groupKey(addr))...)
data1 = append(data1, []byte(a.groupKey(src))...)
hash1 := doubleSha256(data1)
hash64 := binary.BigEndian.Uint64(hash1)
hash64 %= newBucketsPerGroup
var hashbuf [8]byte
binary.BigEndian.PutUint64(hashbuf[:], hash64)
data2 := []byte{}
data2 = append(data2, []byte(a.key)...)
data2 = append(data2, a.groupKey(src)...)
data2 = append(data2, hashbuf[:]...)
hash2 := doubleSha256(data2)
return int(binary.BigEndian.Uint64(hash2) % newBucketCount)
}
// doublesha256( key + group +
// int64(doublesha256(key + addr))%buckets_per_group ) % num_old_buckets
func (a *addrBook) calcOldBucket(addr *p2p.NetAddress) int {
data1 := []byte{}
data1 = append(data1, []byte(a.key)...)
data1 = append(data1, []byte(addr.String())...)
hash1 := doubleSha256(data1)
hash64 := binary.BigEndian.Uint64(hash1)
hash64 %= oldBucketsPerGroup
var hashbuf [8]byte
binary.BigEndian.PutUint64(hashbuf[:], hash64)
data2 := []byte{}
data2 = append(data2, []byte(a.key)...)
data2 = append(data2, a.groupKey(addr)...)
data2 = append(data2, hashbuf[:]...)
hash2 := doubleSha256(data2)
return int(binary.BigEndian.Uint64(hash2) % oldBucketCount)
}
// Return a string representing the network group of this address.
// This is the /16 for IPv4, the /32 (/36 for he.net) for IPv6, the string
// "local" for a local address and the string "unroutable" for an unroutable
// address.
func (a *addrBook) groupKey(na *p2p.NetAddress) string {
if a.routabilityStrict && na.Local() {
return "local"
}
if a.routabilityStrict && !na.Routable() {
return "unroutable"
}
if ipv4 := na.IP.To4(); ipv4 != nil {
return (&net.IPNet{IP: na.IP, Mask: net.CIDRMask(16, 32)}).String()
}
if na.RFC6145() || na.RFC6052() {
// last four bytes are the ip address
ip := na.IP[12:16]
return (&net.IPNet{IP: ip, Mask: net.CIDRMask(16, 32)}).String()
}
if na.RFC3964() {
ip := na.IP[2:7]
return (&net.IPNet{IP: ip, Mask: net.CIDRMask(16, 32)}).String()
}
if na.RFC4380() {
// teredo tunnels have the last 4 bytes as the v4 address XOR
// 0xff.
ip := net.IP(make([]byte, 4))
for i, byte := range na.IP[12:16] {
ip[i] = byte ^ 0xff
}
return (&net.IPNet{IP: ip, Mask: net.CIDRMask(16, 32)}).String()
}
// OK, so now we know ourselves to be a IPv6 address.
// bitcoind uses /32 for everything, except for Hurricane Electric's
// (he.net) IP range, which it uses /36 for.
bits := 32
heNet := &net.IPNet{IP: net.ParseIP("2001:470::"),
Mask: net.CIDRMask(32, 128)}
if heNet.Contains(na.IP) {
bits = 36
}
return (&net.IPNet{IP: na.IP, Mask: net.CIDRMask(bits, 128)}).String()
}
// doubleSha256 calculates sha256(sha256(b)) and returns the resulting bytes.
func doubleSha256(b []byte) []byte {
hasher := sha256.New()
hasher.Write(b) // nolint: errcheck, gas
sum := hasher.Sum(nil)
hasher.Reset()
hasher.Write(sum) // nolint: errcheck, gas
return hasher.Sum(nil)
}