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 common.Hash } func (self *Envelope) Hash() common.Hash { if (self.hash == common.Hash{}) { enc, _ := rlp.EncodeToBytes(self) self.hash = crypto.Sha3Hash(enc) } return self.hash } func NewEnvelope(ttl time.Duration, topics [][]byte, data *Message) *Envelope { exp := time.Now().Add(ttl) return &Envelope{ Expiry: uint32(exp.Unix()), TTL: uint32(ttl.Seconds()), Topics: topics, Data: data.Bytes(), Nonce: 0, } } 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) enc, _ := rlp.EncodeToBytes(self.withoutNonce()) copy(d[:32], enc) 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) enc, _ := rlp.EncodeToBytes(self.withoutNonce()) copy(d[:32], enc) 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, self.Topics, self.Data} } // rlpenv is an Envelope but is not an rlp.Decoder. // It is used for decoding because we need to type rlpenv Envelope func (self *Envelope) DecodeRLP(s *rlp.Stream) error { raw, err := s.Raw() if err != nil { return err } if err := rlp.DecodeBytes(raw, (*rlpenv)(self)); err != nil { return err } self.hash = crypto.Sha3Hash(raw) return nil }