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tendermint/p2p/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 p2p
import (
"crypto/sha256"
"encoding/binary"
"encoding/json"
"fmt"
"math"
"math/rand"
"net"
"os"
"sync"
"time"
crypto "github.com/tendermint/go-crypto"
cmn "github.com/tendermint/tmlibs/common"
)
const (
// addresses under which the address manager will claim to need more addresses.
needAddressThreshold = 1000
// interval used to dump the address cache to disk for future use.
dumpAddressInterval = time.Minute * 2
// max addresses in each old address bucket.
oldBucketSize = 64
// buckets we split old addresses over.
oldBucketCount = 64
// max addresses in each new address bucket.
newBucketSize = 64
// buckets that we spread new addresses over.
newBucketCount = 256
// old buckets over which an address group will be spread.
oldBucketsPerGroup = 4
// new buckets over which a source address group will be spread.
newBucketsPerGroup = 32
// buckets a frequently seen new address may end up in.
maxNewBucketsPerAddress = 4
// days before which we assume an address has vanished
// if we have not seen it announced in that long.
numMissingDays = 30
// tries without a single success before we assume an address is bad.
numRetries = 3
// max failures we will accept without a success before considering an address bad.
maxFailures = 10
// days since the last success before we will consider evicting an address.
minBadDays = 7
// % of total addresses known returned by GetSelection.
getSelectionPercent = 23
// min addresses that must be returned by GetSelection. Useful for bootstrapping.
minGetSelection = 32
// max addresses returned by GetSelection
// NOTE: this must match "maxPexMessageSize"
maxGetSelection = 250
)
const (
bucketTypeNew = 0x01
bucketTypeOld = 0x02
)
// AddrBook - concurrency safe peer address manager.
type AddrBook struct {
cmn.BaseService
// immutable after creation
filePath string
routabilityStrict bool
key string
// accessed concurrently
mtx sync.Mutex
rand *rand.Rand
ourAddrs map[string]*NetAddress
addrLookup map[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: rand.New(rand.NewSource(time.Now().UnixNano())),
ourAddrs: make(map[string]*NetAddress),
addrLookup: make(map[ID]*knownAddress),
filePath: filePath,
routabilityStrict: routabilityStrict,
}
am.init()
am.BaseService = *cmn.NewBaseService(nil, "AddrBook", am)
return am
}
// 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()
}
// AddOurAddress adds another one of our addresses.
func (a *AddrBook) AddOurAddress(addr *NetAddress) {
a.mtx.Lock()
defer a.mtx.Unlock()
a.Logger.Info("Add our address to book", "addr", addr)
a.ourAddrs[addr.String()] = addr
}
// OurAddresses returns a list of our addresses.
func (a *AddrBook) OurAddresses() []*NetAddress {
addrs := []*NetAddress{}
for _, addr := range a.ourAddrs {
addrs = append(addrs, addr)
}
return addrs
}
// AddAddress adds the given address as received from the given source.
// NOTE: addr must not be nil
func (a *AddrBook) AddAddress(addr *NetAddress, src *NetAddress) error {
a.mtx.Lock()
defer a.mtx.Unlock()
return a.addAddress(addr, src)
}
// NeedMoreAddrs returns true if there are not have enough addresses in the book.
func (a *AddrBook) NeedMoreAddrs() bool {
return a.Size() < needAddressThreshold
}
// 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
}
// PickAddress picks an address to connect to.
// The address is picked randomly from an old or new bucket according
// to the newBias 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(newBias int) *NetAddress {
a.mtx.Lock()
defer a.mtx.Unlock()
if a.size() == 0 {
return nil
}
if newBias > 100 {
newBias = 100
}
if newBias < 0 {
newBias = 0
}
// Bias between new and old addresses.
oldCorrelation := math.Sqrt(float64(a.nOld)) * (100.0 - float64(newBias))
newCorrelation := math.Sqrt(float64(a.nNew)) * float64(newBias)
// 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 marks the peer as good and moves it into an "old" bucket.
// TODO: call this from somewhere
func (a *AddrBook) MarkGood(addr *NetAddress) {
a.mtx.Lock()
defer a.mtx.Unlock()
ka := a.addrLookup[addr.ID]
if ka == nil {
return
}
ka.markGood()
if ka.isNew() {
a.moveToOld(ka)
}
}
// MarkAttempt marks that an attempt was made to connect to the address.
func (a *AddrBook) MarkAttempt(addr *NetAddress) {
a.mtx.Lock()
defer a.mtx.Unlock()
ka := a.addrLookup[addr.ID]
if ka == nil {
return
}
ka.markAttempt()
}
// MarkBad currently just ejects the address. In the future, consider
// blacklisting.
func (a *AddrBook) MarkBad(addr *NetAddress) {
a.RemoveAddress(addr)
}
// RemoveAddress removes the address from the book.
func (a *AddrBook) RemoveAddress(addr *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", ka.Addr, "ID", ka.ID)
a.removeFromAllBuckets(ka)
}
/* Peer exchange */
// GetSelection randomly selects some addresses (old & new). Suitable for peer-exchange protocols.
func (a *AddrBook) GetSelection() []*NetAddress {
a.mtx.Lock()
defer a.mtx.Unlock()
if a.size() == 0 {
return nil
}
allAddr := make([]*NetAddress, a.size())
i := 0
for _, ka := range a.addrLookup {
allAddr[i] = ka.Addr
i++
}
numAddresses := cmn.MaxInt(
cmn.MinInt(minGetSelection, len(allAddr)),
len(allAddr)*getSelectionPercent/100)
numAddresses = cmn.MinInt(maxGetSelection, numAddresses)
// Fisher-Yates shuffle the array. We only need to do the first
// `numAddresses' since we are throwing the rest.
// XXX: What's the point of this if we already loop randomly through addrLookup ?
for i := 0; i < numAddresses; i++ {
// pick a number between current index and the end
j := rand.Intn(len(allAddr)-i) + i
allAddr[i], allAddr[j] = allAddr[j], allAddr[i]
}
// slice off the limit we are willing to share.
return allAddr[:numAddresses]
}
// ListOfKnownAddresses returns the new and old addresses.
func (a *AddrBook) ListOfKnownAddresses() []*knownAddress {
a.mtx.Lock()
defer a.mtx.Unlock()
addrs := []*knownAddress{}
for _, addr := range a.addrLookup {
addrs = append(addrs, addr.copy())
}
return addrs
}
func (ka *knownAddress) copy() *knownAddress {
return &knownAddress{
Addr: ka.Addr,
Src: ka.Src,
Attempts: ka.Attempts,
LastAttempt: ka.LastAttempt,
LastSuccess: ka.LastSuccess,
BucketType: ka.BucketType,
Buckets: ka.Buckets,
}
}
/* Loading & Saving */
type addrBookJSON struct {
Key string
Addrs []*knownAddress
}
func (a *AddrBook) saveToFile(filePath string) {
a.Logger.Info("Saving AddrBook to file", "size", a.Size())
a.mtx.Lock()
defer a.mtx.Unlock()
// Compile Addrs
addrs := []*knownAddress{}
for _, ka := range a.addrLookup {
addrs = append(addrs, ka)
}
aJSON := &addrBookJSON{
Key: a.key,
Addrs: addrs,
}
jsonBytes, err := json.MarshalIndent(aJSON, "", "\t")
if err != nil {
a.Logger.Error("Failed to save AddrBook to file", "err", err)
return
}
err = cmn.WriteFileAtomic(filePath, jsonBytes, 0644)
if err != nil {
a.Logger.Error("Failed to save AddrBook to file", "file", filePath, "err", err)
}
}
// Returns false if file does not exist.
// cmn.Panics if file is corrupt.
func (a *AddrBook) loadFromFile(filePath string) bool {
// If doesn't exist, do nothing.
_, err := os.Stat(filePath)
if os.IsNotExist(err) {
return false
}
// Load addrBookJSON{}
r, err := os.Open(filePath)
if err != nil {
cmn.PanicCrisis(cmn.Fmt("Error opening file %s: %v", filePath, err))
}
defer r.Close() // nolint: errcheck
aJSON := &addrBookJSON{}
dec := json.NewDecoder(r)
err = dec.Decode(aJSON)
if err != nil {
cmn.PanicCrisis(cmn.Fmt("Error reading file %s: %v", filePath, err))
}
// Restore all the fields...
// Restore the key
a.key = aJSON.Key
// Restore .bucketsNew & .bucketsOld
for _, ka := range aJSON.Addrs {
for _, bucketIndex := range ka.Buckets {
bucket := a.getBucket(ka.BucketType, bucketIndex)
bucket[ka.Addr.String()] = ka
}
a.addrLookup[ka.ID()] = ka
if ka.BucketType == bucketTypeNew {
a.nNew++
} else {
a.nOld++
}
}
return true
}
// Save saves the book.
func (a *AddrBook) Save() {
a.Logger.Info("Saving AddrBook to file", "size", a.Size())
a.saveToFile(a.filePath)
}
/* Private methods */
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)
a.Logger.Info("Address handler done")
}
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:
cmn.PanicSanity("Should not happen")
return nil
}
}
// 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) bool {
// Sanity check
if ka.isOld() {
a.Logger.Error(cmn.Fmt("Cannot add address already in old bucket to a new bucket: %v", ka))
return false
}
addrStr := ka.Addr.String()
bucket := a.getBucket(bucketTypeNew, bucketIdx)
// Already exists?
if _, ok := bucket[addrStr]; ok {
return true
}
// Enforce max addresses.
if len(bucket) > newBucketSize {
a.Logger.Info("new bucket is full, expiring old ")
a.expireNew(bucketIdx)
}
// Add to bucket.
bucket[addrStr] = ka
if ka.addBucketRef(bucketIdx) == 1 {
a.nNew++
}
// Ensure in addrLookup
a.addrLookup[ka.ID()] = ka
return true
}
// 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(cmn.Fmt("Cannot add new address to old bucket: %v", ka))
return false
}
if len(ka.Buckets) != 0 {
a.Logger.Error(cmn.Fmt("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(cmn.Fmt("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
}
func (a *AddrBook) addAddress(addr, src *NetAddress) error {
if a.routabilityStrict && !addr.Routable() {
return fmt.Errorf("Cannot add non-routable address %v", addr)
}
if _, ok := a.ourAddrs[addr.String()]; ok {
// Ignore our own listener address.
return fmt.Errorf("Cannot add ourselves with address %v", addr)
}
ka := a.addrLookup[addr.ID]
if ka != nil {
// Already old.
if ka.isOld() {
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)
a.Logger.Info("Added new address", "address", addr, "total", a.size())
return nil
}
// 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(cmn.Fmt("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.
// TODO: Move to old probabilistically.
// The better a node is, the less likely it should be evicted from an old bucket.
func (a *AddrBook) moveToOld(ka *knownAddress) {
// Sanity check
if ka.isOld() {
a.Logger.Error(cmn.Fmt("Cannot promote address that is already old %v", ka))
return
}
if len(ka.Buckets) == 0 {
a.Logger.Error(cmn.Fmt("Cannot promote address that isn't in any new buckets %v", ka))
return
}
// Remember one of the buckets in which ka is in.
freedBucket := ka.Buckets[0]
// 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, must evict something
oldest := a.pickOldest(bucketTypeOld, oldBucketIdx)
a.removeFromBucket(oldest, bucketTypeOld, oldBucketIdx)
// Find new bucket to put oldest in
newBucketIdx := a.calcNewBucket(oldest.Addr, oldest.Src)
added := a.addToNewBucket(oldest, newBucketIdx)
// No space in newBucket either, just put it in freedBucket from above.
if !added {
added := a.addToNewBucket(oldest, freedBucket)
if !added {
a.Logger.Error(cmn.Fmt("Could not migrate oldest %v to freedBucket %v", oldest, freedBucket))
}
}
// Finally, add to bucket again.
added = a.addToOldBucket(ka, oldBucketIdx)
if !added {
a.Logger.Error(cmn.Fmt("Could not re-add ka %v to oldBucketIdx %v", ka, oldBucketIdx))
}
}
}
// doublesha256( key + sourcegroup +
// int64(doublesha256(key + group + sourcegroup))%bucket_per_group ) % num_new_buckets
func (a *AddrBook) calcNewBucket(addr, src *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 *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 *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 := net.IP(na.IP[12:16])
return (&net.IPNet{IP: ip, Mask: net.CIDRMask(16, 32)}).String()
}
if na.RFC3964() {
ip := net.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()
}
//-----------------------------------------------------------------------------
/*
knownAddress
tracks information about a known network address that is used
to determine how viable an address is.
*/
type knownAddress struct {
Addr *NetAddress
Src *NetAddress
Attempts int32
LastAttempt time.Time
LastSuccess time.Time
BucketType byte
Buckets []int
}
func newKnownAddress(addr *NetAddress, src *NetAddress) *knownAddress {
return &knownAddress{
Addr: addr,
Src: src,
Attempts: 0,
LastAttempt: time.Now(),
BucketType: bucketTypeNew,
Buckets: nil,
}
}
func (ka *knownAddress) ID() ID {
return ka.Addr.ID
}
func (ka *knownAddress) isOld() bool {
return ka.BucketType == bucketTypeOld
}
func (ka *knownAddress) isNew() bool {
return ka.BucketType == bucketTypeNew
}
func (ka *knownAddress) markAttempt() {
now := time.Now()
ka.LastAttempt = now
ka.Attempts += 1
}
func (ka *knownAddress) markGood() {
now := time.Now()
ka.LastAttempt = now
ka.Attempts = 0
ka.LastSuccess = now
}
func (ka *knownAddress) addBucketRef(bucketIdx int) int {
for _, bucket := range ka.Buckets {
if bucket == bucketIdx {
// TODO refactor to return error?
// log.Warn(Fmt("Bucket already exists in ka.Buckets: %v", ka))
return -1
}
}
ka.Buckets = append(ka.Buckets, bucketIdx)
return len(ka.Buckets)
}
func (ka *knownAddress) removeBucketRef(bucketIdx int) int {
buckets := []int{}
for _, bucket := range ka.Buckets {
if bucket != bucketIdx {
buckets = append(buckets, bucket)
}
}
if len(buckets) != len(ka.Buckets)-1 {
// TODO refactor to return error?
// log.Warn(Fmt("bucketIdx not found in ka.Buckets: %v", ka))
return -1
}
ka.Buckets = buckets
return len(ka.Buckets)
}
/*
An address is bad if the address in question is a New address, has not been tried in the last
minute, and meets one of the following criteria:
1) It claims to be from the future
2) It hasn't been seen in over a month
3) It has failed at least three times and never succeeded
4) It has failed ten times in the last week
All addresses that meet these criteria are assumed to be worthless and not
worth keeping hold of.
XXX: so a good peer needs us to call MarkGood before the conditions above are reached!
*/
func (ka *knownAddress) isBad() bool {
// Is Old --> good
if ka.BucketType == bucketTypeOld {
return false
}
// Has been attempted in the last minute --> good
if ka.LastAttempt.Before(time.Now().Add(-1 * time.Minute)) {
return false
}
// Too old?
// XXX: does this mean if we've kept a connection up for this long we'll disconnect?!
// and shouldn't it be .Before ?
if ka.LastAttempt.After(time.Now().Add(-1 * numMissingDays * time.Hour * 24)) {
return true
}
// Never succeeded?
if ka.LastSuccess.IsZero() && ka.Attempts >= numRetries {
return true
}
// Hasn't succeeded in too long?
// XXX: does this mean if we've kept a connection up for this long we'll disconnect?!
if ka.LastSuccess.Before(time.Now().Add(-1*minBadDays*time.Hour*24)) &&
ka.Attempts >= maxFailures {
return true
}
return false
}
//-----------------------------------------------------------------------------
// 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)
}