First draft of Whisper messages relaying

whisper/envelope.go

@@ -0,0 +1,96 @@
+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 (
+	DefaultTtl = 50 * time.Second
+)
+
+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(DefaultTtl)
+}
+
+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}
+}