/*
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#################### ####################
#################### EDIT AND YOU SHALL FEEL MY WRATH - jeff ####################
#################### ####################
###################################################################################
###################################################################################
*/
package ethash
/*
#cgo CFLAGS: -std=gnu99 -Wall
#include "src/libethash/util.c"
#include "src/libethash/internal.c"
#include "src/libethash/sha3.c"
*/
import "C"
import (
"bytes"
"encoding/binary"
"fmt"
"io/ioutil"
"math/big"
"math/rand"
"os"
"path"
"sync"
"time"
"unsafe"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/logger"
"github.com/ethereum/go-ethereum/pow"
)
var minDifficulty = new(big.Int).Exp(big.NewInt(2), big.NewInt(256), big.NewInt(0))
var powlogger = logger.NewLogger("POW")
type ParamsAndCache struct {
params *C.ethash_params
cache *C.ethash_cache
Epoch uint64
}
type DAG struct {
dag unsafe.Pointer // full GB of memory for dag
file bool
paramsAndCache *ParamsAndCache
}
type Ethash struct {
turbo bool
HashRate int64
chainManager pow.ChainManager
dag *DAG
paramsAndCache *ParamsAndCache
ret *C.ethash_return_value
dagMutex *sync.RWMutex
cacheMutex *sync.RWMutex
}
func parseNonce(nonce []byte) (uint64, error) {
nonceBuf := bytes.NewBuffer(nonce)
nonceInt, err := binary.ReadUvarint(nonceBuf)
if err != nil {
return 0, err
}
return nonceInt, nil
}
const epochLength uint64 = 30000
func makeParamsAndCache(chainManager pow.ChainManager, blockNum uint64) (*ParamsAndCache, error) {
if blockNum >= epochLength*2048 {
return nil, fmt.Errorf("block number is out of bounds (value %v, limit is %v)", blockNum, epochLength*2048)
}
paramsAndCache := &ParamsAndCache{
params: new(C.ethash_params),
cache: new(C.ethash_cache),
Epoch: blockNum / epochLength,
}
C.ethash_params_init(paramsAndCache.params, C.uint32_t(uint32(blockNum)))
paramsAndCache.cache.mem = C.malloc(C.size_t(paramsAndCache.params.cache_size))
seedHash, err := GetSeedHash(blockNum)
if err != nil {
return nil, err
}
powlogger.Infoln("Making Cache")
start := time.Now()
C.ethash_mkcache(paramsAndCache.cache, paramsAndCache.params, (*C.uint8_t)(unsafe.Pointer(&seedHash[0])))
powlogger.Infoln("Took:", time.Since(start))
return paramsAndCache, nil
}
func (pow *Ethash) UpdateCache(force bool) error {
pow.cacheMutex.Lock()
defer pow.cacheMutex.Unlock()
thisEpoch := pow.chainManager.CurrentBlock().NumberU64() / epochLength
if force || pow.paramsAndCache.Epoch != thisEpoch {
var err error
pow.paramsAndCache, err = makeParamsAndCache(pow.chainManager, pow.chainManager.CurrentBlock().NumberU64())
if err != nil {
panic(err)
}
}
return nil
}
func makeDAG(p *ParamsAndCache) *DAG {
d := &DAG{
dag: C.malloc(C.size_t(p.params.full_size)),
file: false,
paramsAndCache: p,
}
donech := make(chan string)
go func() {
t := time.NewTicker(5 * time.Second)
tstart := time.Now()
done:
for {
select {
case <-t.C:
powlogger.Infof("... still generating DAG (%v) ...\n", time.Since(tstart).Seconds())
case str := <-donech:
powlogger.Infof("... %s ...\n", str)
break done
}
}
}()
C.ethash_compute_full_data(d.dag, p.params, p.cache)
donech <- "DAG generation completed"
return d
}
func (pow *Ethash) writeDagToDisk(dag *DAG, epoch uint64) *os.File {
if epoch > 2048 {
panic(fmt.Errorf("Epoch must be less than 2048 (is %v)", epoch))
}
data := C.GoBytes(unsafe.Pointer(dag.dag), C.int(dag.paramsAndCache.params.full_size))
file, err := os.Create("/tmp/dag")
if err != nil {
panic(err)
}
dataEpoch := make([]byte, 8)
binary.BigEndian.PutUint64(dataEpoch, epoch)
file.Write(dataEpoch)
file.Write(data)
return file
}
func (pow *Ethash) UpdateDAG() {
blockNum := pow.chainManager.CurrentBlock().NumberU64()
if blockNum >= epochLength*2048 {
// This will crash in the 2030s or 2040s
panic(fmt.Errorf("Current block number is out of bounds (value %v, limit is %v)", blockNum, epochLength*2048))
}
pow.dagMutex.Lock()
defer pow.dagMutex.Unlock()
thisEpoch := blockNum / epochLength
if pow.dag == nil || pow.dag.paramsAndCache.Epoch != thisEpoch {
if pow.dag != nil && pow.dag.dag != nil {
C.free(pow.dag.dag)
pow.dag.dag = nil
}
if pow.dag != nil && pow.dag.paramsAndCache.cache.mem != nil {
C.free(pow.dag.paramsAndCache.cache.mem)
pow.dag.paramsAndCache.cache.mem = nil
}
// Make the params and cache for the DAG
paramsAndCache, err := makeParamsAndCache(pow.chainManager, blockNum)
if err != nil {
panic(err)
}
// TODO: On non-SSD disks, loading the DAG from disk takes longer than generating it in memory
pow.paramsAndCache = paramsAndCache
path := path.Join("/", "tmp", "dag")
pow.dag = nil
powlogger.Infoln("Retrieving DAG")
start := time.Now()
file, err := os.Open(path)
if err != nil {
powlogger.Infof("No DAG found. Generating new DAG in '%s' (this takes a while)...\n", path)
pow.dag = makeDAG(paramsAndCache)
file = pow.writeDagToDisk(pow.dag, thisEpoch)
pow.dag.file = true
} else {
data, err := ioutil.ReadAll(file)
if err != nil {
powlogger.Infof("DAG load err: %v\n", err)
}
if len(data) < 8 {
powlogger.Infof("DAG in '%s' is less than 8 bytes, it must be corrupted. Generating new DAG (this takes a while)...\n", path)
pow.dag = makeDAG(paramsAndCache)
file = pow.writeDagToDisk(pow.dag, thisEpoch)
pow.dag.file = true
} else {
dataEpoch := binary.BigEndian.Uint64(data[0:8])
if dataEpoch < thisEpoch {
powlogger.Infof("DAG in '%s' is stale. Generating new DAG (this takes a while)...\n", path)
pow.dag = makeDAG(paramsAndCache)
file = pow.writeDagToDisk(pow.dag, thisEpoch)
pow.dag.file = true
} else if dataEpoch > thisEpoch {
// FIXME
panic(fmt.Errorf("Saved DAG in '%s' reports to be from future epoch %v (current epoch is %v)\n", path, dataEpoch, thisEpoch))
} else if len(data) != (int(paramsAndCache.params.full_size) + 8) {
powlogger.Infof("DAG in '%s' is corrupted. Generating new DAG (this takes a while)...\n", path)
pow.dag = makeDAG(paramsAndCache)
file = pow.writeDagToDisk(pow.dag, thisEpoch)
pow.dag.file = true
} else {
data = data[8:]
pow.dag = &DAG{
dag: unsafe.Pointer(&data[0]),
file: true,
paramsAndCache: paramsAndCache,
}
}
}
}
powlogger.Infoln("Took:", time.Since(start))
file.Close()
}
}
func New(chainManager pow.ChainManager) *Ethash {
paramsAndCache, err := makeParamsAndCache(chainManager, chainManager.CurrentBlock().NumberU64())
if err != nil {
panic(err)
}
return &Ethash{
turbo: true,
paramsAndCache: paramsAndCache,
chainManager: chainManager,
dag: nil,
cacheMutex: new(sync.RWMutex),
dagMutex: new(sync.RWMutex),
}
}
func (pow *Ethash) DAGSize() uint64 {
return uint64(pow.dag.paramsAndCache.params.full_size)
}
func (pow *Ethash) CacheSize() uint64 {
return uint64(pow.paramsAndCache.params.cache_size)
}
func GetSeedHash(blockNum uint64) ([]byte, error) {
if blockNum >= epochLength*2048 {
return nil, fmt.Errorf("block number is out of bounds (value %v, limit is %v)", blockNum, epochLength*2048)
}
epoch := blockNum / epochLength
seedHash := make([]byte, 32)
var i uint64
for i = 0; i < 32; i++ {
seedHash[i] = 0
}
for i = 0; i < epoch; i++ {
seedHash = crypto.Sha3(seedHash)
}
return seedHash, nil
}
func (pow *Ethash) Stop() {
pow.cacheMutex.Lock()
pow.dagMutex.Lock()
defer pow.dagMutex.Unlock()
defer pow.cacheMutex.Unlock()
if pow.paramsAndCache.cache != nil {
C.free(pow.paramsAndCache.cache.mem)
}
if pow.dag.dag != nil && !pow.dag.file {
C.free(pow.dag.dag)
}
if pow.dag != nil && pow.dag.paramsAndCache != nil && pow.dag.paramsAndCache.cache.mem != nil {
C.free(pow.dag.paramsAndCache.cache.mem)
pow.dag.paramsAndCache.cache.mem = nil
}
pow.dag.dag = nil
}
func (pow *Ethash) Search(block pow.Block, stop <-chan struct{}) (uint64, []byte, []byte) {
pow.UpdateDAG()
pow.dagMutex.RLock()
defer pow.dagMutex.RUnlock()
r := rand.New(rand.NewSource(time.Now().UnixNano()))
miningHash := block.HashNoNonce()
diff := block.Difficulty()
i := int64(0)
starti := i
start := time.Now().UnixNano()
nonce := uint64(r.Int63())
cMiningHash := (*C.uint8_t)(unsafe.Pointer(&miningHash[0]))
target := new(big.Int).Div(minDifficulty, diff)
var ret C.ethash_return_value
for {
select {
case <-stop:
powlogger.Infoln("Breaking from mining")
pow.HashRate = 0
return 0, nil, nil
default:
i++
elapsed := time.Now().UnixNano() - start
hashes := ((float64(1e9) / float64(elapsed)) * float64(i-starti)) / 1000
pow.HashRate = int64(hashes)
C.ethash_full(&ret, pow.dag.dag, pow.dag.paramsAndCache.params, cMiningHash, C.uint64_t(nonce))
result := common.Bytes2Big(C.GoBytes(unsafe.Pointer(&ret.result[0]), C.int(32)))
// TODO: disagrees with the spec https://github.com/ethereum/wiki/wiki/Ethash#mining
if result.Cmp(target) <= 0 {
mixDigest := C.GoBytes(unsafe.Pointer(&ret.mix_hash[0]), C.int(32))
seedHash, err := GetSeedHash(block.NumberU64()) // This seedhash is useless
if err != nil {
panic(err)
}
return nonce, mixDigest, seedHash
}
nonce += 1
}
if !pow.turbo {
time.Sleep(20 * time.Microsecond)
}
}
}
func (pow *Ethash) Verify(block pow.Block) bool {
return pow.verify(block.HashNoNonce().Bytes(), block.MixDigest().Bytes(), block.Difficulty(), block.NumberU64(), block.Nonce())
}
func (pow *Ethash) verify(hash []byte, mixDigest []byte, difficulty *big.Int, blockNum uint64, nonce uint64) bool {
// Make sure the block num is valid
if blockNum >= epochLength*2048 {
powlogger.Infoln(fmt.Sprintf("Block number exceeds limit, invalid (value is %v, limit is %v)",
blockNum, epochLength*2048))
return false
}
// First check: make sure header, mixDigest, nonce are correct without hitting the cache
// This is to prevent DOS attacks
chash := (*C.uint8_t)(unsafe.Pointer(&hash[0]))
cnonce := C.uint64_t(nonce)
target := new(big.Int).Div(minDifficulty, difficulty)
var pAc *ParamsAndCache
// If its an old block (doesn't use the current cache)
// get the cache for it but don't update (so we don't need the mutex)
// Otherwise, it's the current block or a future block.
// If current, updateCache will do nothing.
if blockNum/epochLength < pow.paramsAndCache.Epoch {
var err error
// If we can't make the params for some reason, this block is invalid
pAc, err = makeParamsAndCache(pow.chainManager, blockNum)
if err != nil {
powlogger.Infoln(err)
return false
}
} else {
pow.UpdateCache(false)
pow.cacheMutex.RLock()
defer pow.cacheMutex.RUnlock()
pAc = pow.paramsAndCache
}
ret := new(C.ethash_return_value)
C.ethash_light(ret, pAc.cache, pAc.params, chash, cnonce)
result := common.Bytes2Big(C.GoBytes(unsafe.Pointer(&ret.result[0]), C.int(32)))
return result.Cmp(target) <= 0
}
func (pow *Ethash) GetHashrate() int64 {
return pow.HashRate
}
func (pow *Ethash) Turbo(on bool) {
pow.turbo = on
}
func (pow *Ethash) FullHash(nonce uint64, miningHash []byte) []byte {
pow.UpdateDAG()
pow.dagMutex.Lock()
defer pow.dagMutex.Unlock()
cMiningHash := (*C.uint8_t)(unsafe.Pointer(&miningHash[0]))
cnonce := C.uint64_t(nonce)
ret := new(C.ethash_return_value)
// pow.hash is the output/return of ethash_full
C.ethash_full(ret, pow.dag.dag, pow.paramsAndCache.params, cMiningHash, cnonce)
ghash_full := C.GoBytes(unsafe.Pointer(&ret.result), 32)
return ghash_full
}
func (pow *Ethash) LightHash(nonce uint64, miningHash []byte) []byte {
cMiningHash := (*C.uint8_t)(unsafe.Pointer(&miningHash[0]))
cnonce := C.uint64_t(nonce)
ret := new(C.ethash_return_value)
C.ethash_light(ret, pow.paramsAndCache.cache, pow.paramsAndCache.params, cMiningHash, cnonce)
ghash_light := C.GoBytes(unsafe.Pointer(&ret.result), 32)
return ghash_light
}