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package whisper
import (
"bytes"
"encoding/binary"
"io"
"time"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/ethutil"
"github.com/ethereum/go-ethereum/rlp"
)
const (
DefaultPow = 50 * time.Millisecond
)
type Envelope struct {
Expiry int32 // Whisper protocol specifies int32, really should be int64
Ttl int32 // ^^^^^^
Topics [][]byte
Data []byte
Nonce uint32
hash Hash
}
func NewEnvelopeFromReader(reader io.Reader) (*Envelope, error) {
var envelope Envelope
buf := new(bytes.Buffer)
buf.ReadFrom(reader)
h := H(crypto.Sha3(buf.Bytes()))
if err := rlp.Decode(buf, &envelope); err != nil {
return nil, err
}
envelope.hash = h
return &envelope, nil
}
func (self *Envelope) Hash() Hash {
if self.hash == EmptyHash {
self.hash = H(crypto.Sha3(ethutil.Encode(self)))
}
return self.hash
}
func NewEnvelope(ttl time.Duration, topics [][]byte, data *Message) *Envelope {
exp := time.Now().Add(ttl)
return &Envelope{int32(exp.Unix()), int32(ttl.Seconds()), topics, data.Bytes(), 0, Hash{}}
}
func (self *Envelope) Seal() {
self.proveWork(DefaultPow)
}
func (self *Envelope) proveWork(dura time.Duration) {
var bestBit int
d := make([]byte, 64)
copy(d[:32], ethutil.Encode(self.withoutNonce()))
then := time.Now().Add(dura).UnixNano()
for n := uint32(0); time.Now().UnixNano() < then; {
for i := 0; i < 1024; i++ {
binary.BigEndian.PutUint32(d[60:], n)
fbs := ethutil.FirstBitSet(ethutil.BigD(crypto.Sha3(d)))
if fbs > bestBit {
bestBit = fbs
self.Nonce = n
}
n++
}
}
}
func (self *Envelope) valid() bool {
d := make([]byte, 64)
copy(d[:32], ethutil.Encode(self.withoutNonce()))
binary.BigEndian.PutUint32(d[60:], self.Nonce)
return ethutil.FirstBitSet(ethutil.BigD(crypto.Sha3(d))) > 0
}
func (self *Envelope) withoutNonce() interface{} {
return []interface{}{self.Expiry, self.Ttl, ethutil.ByteSliceToInterface(self.Topics), self.Data}
}
func (self *Envelope) RlpData() interface{} {
return []interface{}{self.Expiry, self.Ttl, ethutil.ByteSliceToInterface(self.Topics), self.Data, self.Nonce}
}
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