gaspersic/go-ethereum
1
0
Fork 0
Code Issues Pull Requests Projects Releases Wiki Activity

eth/downloader: bound fork ancestry and allow heavy short forks

Browse Source
This commit is contained in:
Péter Szilágyi
2016-05-13 12:12:13 +02:00
parent 72e60dea36
commit 39ce85cf5d
2 changed files with 200 additions and 42 deletions
Download Patch File Download Diff File Expand all files Collapse all files

68
eth/downloader/downloader.go
View File

@ -34,6 +34,7 @@ import (
"github.com/ethereum/go-ethereum/event"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/logger/glog"
"github.com/ethereum/go-ethereum/params"
"github.com/rcrowley/go-metrics"
)
@ -45,6 +46,8 @@ var (
MaxReceiptFetch = 256 // Amount of transaction receipts to allow fetching per request
MaxStateFetch = 384 // Amount of node state values to allow fetching per request
MaxForkAncestry = 3 * params.EpochDuration.Uint64() // Maximum chain reorganisation
hashTTL = 3 * time.Second // [eth/61] Time it takes for a hash request to time out
blockTargetRTT = 3 * time.Second / 2 // [eth/61] Target time for completing a block retrieval request
blockTTL = 3 * blockTargetRTT // [eth/61] Maximum time allowance before a block request is considered expired
@ -79,6 +82,7 @@ var (
errEmptyHeaderSet = errors.New("empty header set by peer")
errPeersUnavailable = errors.New("no peers available or all tried for download")
errAlreadyInPool = errors.New("hash already in pool")
errInvalidAncestor = errors.New("retrieved ancestor is invalid")
errInvalidChain = errors.New("retrieved hash chain is invalid")
errInvalidBlock = errors.New("retrieved block is invalid")
errInvalidBody = errors.New("retrieved block body is invalid")
@ -266,7 +270,7 @@ func (d *Downloader) Synchronise(id string, head common.Hash, td *big.Int, mode
case errBusy:
glog.V(logger.Detail).Infof("Synchronisation already in progress")
case errTimeout, errBadPeer, errStallingPeer, errEmptyHashSet, errEmptyHeaderSet, errPeersUnavailable, errInvalidChain:
case errTimeout, errBadPeer, errStallingPeer, errEmptyHashSet, errEmptyHeaderSet, errPeersUnavailable, errInvalidAncestor, errInvalidChain:
glog.V(logger.Debug).Infof("Removing peer %v: %v", id, err)
d.dropPeer(id)
@ -353,7 +357,7 @@ func (d *Downloader) syncWithPeer(p *peer, hash common.Hash, td *big.Int) (err e
if err != nil {
return err
}
origin, err := d.findAncestor61(p)
origin, err := d.findAncestor61(p, latest)
if err != nil {
return err
}
@ -380,7 +384,7 @@ func (d *Downloader) syncWithPeer(p *peer, hash common.Hash, td *big.Int) (err e
if err != nil {
return err
}
origin, err := d.findAncestor(p)
origin, err := d.findAncestor(p, latest)
if err != nil {
return err
}
@ -536,11 +540,19 @@ func (d *Downloader) fetchHeight61(p *peer) (uint64, error) {
// on the correct chain, checking the top N blocks should already get us a match.
// In the rare scenario when we ended up on a long reorganisation (i.e. none of
// the head blocks match), we do a binary search to find the common ancestor.
func (d *Downloader) findAncestor61(p *peer) (uint64, error) {
func (d *Downloader) findAncestor61(p *peer, height uint64) (uint64, error) {
glog.V(logger.Debug).Infof("%v: looking for common ancestor", p)
// Request out head blocks to short circuit ancestor location
head := d.headBlock().NumberU64()
// Figure out the valid ancestor range to prevent rewrite attacks
floor, ceil := int64(-1), d.headBlock().NumberU64()
if ceil >= MaxForkAncestry {
floor = int64(ceil - MaxForkAncestry)
}
// Request the topmost blocks to short circuit binary ancestor lookup
head := ceil
if head > height {
head = height
}
from := int64(head) - int64(MaxHashFetch) + 1
if from < 0 {
from = 0
@ -600,11 +612,18 @@ func (d *Downloader) findAncestor61(p *peer) (uint64, error) {
}
// If the head fetch already found an ancestor, return
if !common.EmptyHash(hash) {
if int64(number) <= floor {
glog.V(logger.Warn).Infof("%v: potential rewrite attack: #%d [%x…] <= #%d limit", p, number, hash[:4], floor)
return 0, errInvalidAncestor
}
glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x…]", p, number, hash[:4])
return number, nil
}
// Ancestor not found, we need to binary search over our chain
start, end := uint64(0), head
if floor > 0 {
start = uint64(floor)
}
for start+1 < end {
// Split our chain interval in two, and request the hash to cross check
check := (start + end) / 2
@ -660,6 +679,12 @@ func (d *Downloader) findAncestor61(p *peer) (uint64, error) {
}
}
}
// Ensure valid ancestry and return
if int64(start) <= floor {
glog.V(logger.Warn).Infof("%v: potential rewrite attack: #%d [%x…] <= #%d limit", p, start, hash[:4], floor)
return 0, errInvalidAncestor
}
glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x…]", p, start, hash[:4])
return start, nil
}
@ -961,15 +986,23 @@ func (d *Downloader) fetchHeight(p *peer) (uint64, error) {
// on the correct chain, checking the top N links should already get us a match.
// In the rare scenario when we ended up on a long reorganisation (i.e. none of
// the head links match), we do a binary search to find the common ancestor.
func (d *Downloader) findAncestor(p *peer) (uint64, error) {
func (d *Downloader) findAncestor(p *peer, height uint64) (uint64, error) {
glog.V(logger.Debug).Infof("%v: looking for common ancestor", p)
// Request our head headers to short circuit ancestor location
head := d.headHeader().Number.Uint64()
// Figure out the valid ancestor range to prevent rewrite attacks
floor, ceil := int64(-1), d.headHeader().Number.Uint64()
if d.mode == FullSync {
head = d.headBlock().NumberU64()
ceil = d.headBlock().NumberU64()
} else if d.mode == FastSync {
head = d.headFastBlock().NumberU64()
ceil = d.headFastBlock().NumberU64()
}
if ceil >= MaxForkAncestry {
floor = int64(ceil - MaxForkAncestry)
}
// Request the topmost blocks to short circuit binary ancestor lookup
head := ceil
if head > height {
head = height
}
from := int64(head) - int64(MaxHeaderFetch) + 1
if from < 0 {
@ -1040,11 +1073,18 @@ func (d *Downloader) findAncestor(p *peer) (uint64, error) {
}
// If the head fetch already found an ancestor, return
if !common.EmptyHash(hash) {
if int64(number) <= floor {
glog.V(logger.Warn).Infof("%v: potential rewrite attack: #%d [%x…] <= #%d limit", p, number, hash[:4], floor)
return 0, errInvalidAncestor
}
glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x…]", p, number, hash[:4])
return number, nil
}
// Ancestor not found, we need to binary search over our chain
start, end := uint64(0), head
if floor > 0 {
start = uint64(floor)
}
for start+1 < end {
// Split our chain interval in two, and request the hash to cross check
check := (start + end) / 2
@ -1100,6 +1140,12 @@ func (d *Downloader) findAncestor(p *peer) (uint64, error) {
}
}
}
// Ensure valid ancestry and return
if int64(start) <= floor {
glog.V(logger.Warn).Infof("%v: potential rewrite attack: #%d [%x…] <= #%d limit", p, start, hash[:4], floor)
return 0, errInvalidAncestor
}
glog.V(logger.Debug).Infof("%v: common ancestor: #%d [%x…]", p, start, hash[:4])
return start, nil
}