122 lines
2.7 KiB
Go
122 lines
2.7 KiB
Go
package whisper
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import (
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"bytes"
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"crypto/ecdsa"
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"encoding/binary"
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"fmt"
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"io"
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"time"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/ethutil"
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"github.com/ethereum/go-ethereum/rlp"
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)
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const (
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DefaultPow = 50 * time.Millisecond
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)
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type Envelope struct {
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Expiry uint32 // Whisper protocol specifies int32, really should be int64
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Ttl uint32 // ^^^^^^
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Topics [][]byte
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Data []byte
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Nonce uint32
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hash Hash
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}
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func NewEnvelopeFromReader(reader io.Reader) (*Envelope, error) {
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var envelope Envelope
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buf := new(bytes.Buffer)
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buf.ReadFrom(reader)
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h := H(crypto.Sha3(buf.Bytes()))
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if err := rlp.Decode(buf, &envelope); err != nil {
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return nil, err
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}
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envelope.hash = h
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return &envelope, nil
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}
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func (self *Envelope) Hash() Hash {
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if self.hash == EmptyHash {
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self.hash = H(crypto.Sha3(ethutil.Encode(self)))
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}
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return self.hash
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}
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func NewEnvelope(ttl time.Duration, topics [][]byte, data *Message) *Envelope {
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exp := time.Now().Add(ttl)
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return &Envelope{uint32(exp.Unix()), uint32(ttl.Seconds()), topics, data.Bytes(), 0, Hash{}}
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}
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func (self *Envelope) Seal(pow time.Duration) {
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self.proveWork(pow)
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}
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func (self *Envelope) Open(prv *ecdsa.PrivateKey) (msg *Message, err error) {
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data := self.Data
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var message Message
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dataStart := 1
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if data[0] > 0 {
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if len(data) < 66 {
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return nil, fmt.Errorf("unable to open envelope. First bit set but len(data) < 66")
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}
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dataStart = 66
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message.Flags = data[0]
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message.Signature = data[1:66]
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}
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message.Payload = data[dataStart:]
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if prv != nil {
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message.Payload, err = crypto.Decrypt(prv, message.Payload)
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if err != nil {
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return nil, fmt.Errorf("unable to open envelope. Decrypt failed: %v", err)
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}
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}
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return &message, nil
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}
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func (self *Envelope) proveWork(dura time.Duration) {
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var bestBit int
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d := make([]byte, 64)
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copy(d[:32], ethutil.Encode(self.withoutNonce()))
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then := time.Now().Add(dura).UnixNano()
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for n := uint32(0); time.Now().UnixNano() < then; {
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for i := 0; i < 1024; i++ {
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binary.BigEndian.PutUint32(d[60:], n)
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fbs := ethutil.FirstBitSet(ethutil.BigD(crypto.Sha3(d)))
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if fbs > bestBit {
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bestBit = fbs
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self.Nonce = n
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}
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n++
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}
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}
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}
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func (self *Envelope) valid() bool {
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d := make([]byte, 64)
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copy(d[:32], ethutil.Encode(self.withoutNonce()))
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binary.BigEndian.PutUint32(d[60:], self.Nonce)
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return ethutil.FirstBitSet(ethutil.BigD(crypto.Sha3(d))) > 0
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}
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func (self *Envelope) withoutNonce() interface{} {
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return []interface{}{self.Expiry, self.Ttl, ethutil.ByteSliceToInterface(self.Topics), self.Data}
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}
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func (self *Envelope) RlpData() interface{} {
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return []interface{}{self.Expiry, self.Ttl, ethutil.ByteSliceToInterface(self.Topics), self.Data, self.Nonce}
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}
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