package whisper import ( "crypto/ecdsa" "encoding/binary" "fmt" "time" "github.com/ethereum/go-ethereum/common" "github.com/ethereum/go-ethereum/crypto" "github.com/ethereum/go-ethereum/crypto/ecies" "github.com/ethereum/go-ethereum/rlp" ) const ( DefaultPow = 50 * time.Millisecond ) type Envelope struct { Expiry uint32 // Whisper protocol specifies int32, really should be int64 Ttl uint32 // ^^^^^^ Topics [][]byte Data []byte Nonce uint32 hash Hash } func (self *Envelope) Hash() Hash { if self.hash == EmptyHash { self.hash = H(crypto.Sha3(common.Encode(self))) } return self.hash } func NewEnvelope(ttl time.Duration, topics [][]byte, data *Message) *Envelope { exp := time.Now().Add(ttl) return &Envelope{uint32(exp.Unix()), uint32(ttl.Seconds()), topics, data.Bytes(), 0, Hash{}} } func (self *Envelope) Seal(pow time.Duration) { self.proveWork(pow) } func (self *Envelope) Open(prv *ecdsa.PrivateKey) (msg *Message, err error) { data := self.Data var message Message dataStart := 1 if data[0] > 0 { if len(data) < 66 { return nil, fmt.Errorf("unable to open envelope. First bit set but len(data) < 66") } dataStart = 66 message.Flags = data[0] message.Signature = data[1:66] } payload := data[dataStart:] if prv != nil { message.Payload, err = crypto.Decrypt(prv, payload) switch err { case nil: // OK case ecies.ErrInvalidPublicKey: // Payload isn't encrypted message.Payload = payload return &message, err default: return nil, fmt.Errorf("unable to open envelope. Decrypt failed: %v", err) } } return &message, nil } func (self *Envelope) proveWork(dura time.Duration) { var bestBit int d := make([]byte, 64) copy(d[:32], common.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 := common.FirstBitSet(common.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], common.Encode(self.withoutNonce())) binary.BigEndian.PutUint32(d[60:], self.Nonce) return common.FirstBitSet(common.BigD(crypto.Sha3(d))) > 0 } func (self *Envelope) withoutNonce() interface{} { return []interface{}{self.Expiry, self.Ttl, common.ByteSliceToInterface(self.Topics), self.Data} } func (self *Envelope) RlpData() interface{} { return []interface{}{self.Expiry, self.Ttl, common.ByteSliceToInterface(self.Topics), self.Data, self.Nonce} } func (self *Envelope) DecodeRLP(s *rlp.Stream) error { var extenv struct { Expiry uint32 Ttl uint32 Topics [][]byte Data []byte Nonce uint32 } if err := s.Decode(&extenv); err != nil { return err } self.Expiry = extenv.Expiry self.Ttl = extenv.Ttl self.Topics = extenv.Topics self.Data = extenv.Data self.Nonce = extenv.Nonce // TODO We should use the stream directly here. self.hash = H(crypto.Sha3(common.Encode(self))) return nil }