130 lines
2.8 KiB
Go
130 lines
2.8 KiB
Go
package whisper
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import (
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"crypto/ecdsa"
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"encoding/binary"
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"fmt"
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"time"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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"github.com/ethereum/go-ethereum/crypto/ecies"
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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 common.Hash
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}
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func (self *Envelope) Hash() common.Hash {
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if (self.hash == common.Hash{}) {
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enc, _ := rlp.EncodeToBytes(self)
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self.hash = crypto.Sha3Hash(enc)
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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{
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Expiry: uint32(exp.Unix()),
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TTL: uint32(ttl.Seconds()),
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Topics: topics,
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Data: data.Bytes(),
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Nonce: 0,
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}
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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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payload := data[dataStart:]
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if prv != nil {
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message.Payload, err = crypto.Decrypt(prv, payload)
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switch err {
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case nil: // OK
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case ecies.ErrInvalidPublicKey: // Payload isn't encrypted
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message.Payload = payload
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return &message, err
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default:
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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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enc, _ := rlp.EncodeToBytes(self.withoutNonce())
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copy(d[:32], enc)
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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 := common.FirstBitSet(common.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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enc, _ := rlp.EncodeToBytes(self.withoutNonce())
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copy(d[:32], enc)
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binary.BigEndian.PutUint32(d[60:], self.Nonce)
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return common.FirstBitSet(common.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, self.Topics, self.Data}
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}
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// rlpenv is an Envelope but is not an rlp.Decoder.
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// It is used for decoding because we need to
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type rlpenv Envelope
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func (self *Envelope) DecodeRLP(s *rlp.Stream) error {
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raw, err := s.Raw()
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if err != nil {
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return err
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}
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if err := rlp.DecodeBytes(raw, (*rlpenv)(self)); err != nil {
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return err
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}
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self.hash = crypto.Sha3Hash(raw)
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return nil
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}
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