1 files changed, 147 insertions, 0 deletions
diff --git a/whisper/whisperv2/envelope.go b/whisper/whisperv2/envelope.go
new file mode 100644
index 000000000..7110ab457
--- /dev/null
+++ b/whisper/whisperv2/envelope.go
@@ -0,0 +1,147 @@
+// Copyright 2014 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+// Contains the Whisper protocol Envelope element. For formal details please see
+// the specs at https://github.com/ethereum/wiki/wiki/Whisper-PoC-1-Protocol-Spec#envelopes.
+
+package whisperv2
+
+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"
+)
+
+// Envelope represents a clear-text data packet to transmit through the Whisper
+// network. Its contents may or may not be encrypted and signed.
+type Envelope struct {
+	Expiry uint32 // Whisper protocol specifies int32, really should be int64
+	TTL    uint32 // ^^^^^^
+	Topics []Topic
+	Data   []byte
+	Nonce  uint32
+
+	hash common.Hash // Cached hash of the envelope to avoid rehashing every time
+}
+
+// NewEnvelope wraps a Whisper message with expiration and destination data
+// included into an envelope for network forwarding.
+func NewEnvelope(ttl time.Duration, topics []Topic, msg *Message) *Envelope {
+	return &Envelope{
+		Expiry: uint32(time.Now().Add(ttl).Unix()),
+		TTL:    uint32(ttl.Seconds()),
+		Topics: topics,
+		Data:   msg.bytes(),
+		Nonce:  0,
+	}
+}
+
+// Seal closes the envelope by spending the requested amount of time as a proof
+// of work on hashing the data.
+func (self *Envelope) Seal(pow time.Duration) {
+	d := make([]byte, 64)
+	copy(d[:32], self.rlpWithoutNonce())
+
+	finish, bestBit := time.Now().Add(pow).UnixNano(), 0
+	for nonce := uint32(0); time.Now().UnixNano() < finish; {
+		for i := 0; i < 1024; i++ {
+			binary.BigEndian.PutUint32(d[60:], nonce)
+
+			firstBit := common.FirstBitSet(common.BigD(crypto.Keccak256(d)))
+			if firstBit > bestBit {
+				self.Nonce, bestBit = nonce, firstBit
+			}
+			nonce++
+		}
+	}
+}
+
+// rlpWithoutNonce returns the RLP encoded envelope contents, except the nonce.
+func (self *Envelope) rlpWithoutNonce() []byte {
+	enc, _ := rlp.EncodeToBytes([]interface{}{self.Expiry, self.TTL, self.Topics, self.Data})
+	return enc
+}
+
+// Open extracts the message contained within a potentially encrypted envelope.
+func (self *Envelope) Open(key *ecdsa.PrivateKey) (msg *Message, err error) {
+	// Split open the payload into a message construct
+	data := self.Data
+
+	message := &Message{
+		Flags: data[0],
+		Sent:  time.Unix(int64(self.Expiry-self.TTL), 0),
+		TTL:   time.Duration(self.TTL) * time.Second,
+		Hash:  self.Hash(),
+	}
+	data = data[1:]
+
+	if message.Flags&signatureFlag == signatureFlag {
+		if len(data) < signatureLength {
+			return nil, fmt.Errorf("unable to open envelope. First bit set but len(data) < len(signature)")
+		}
+		message.Signature, data = data[:signatureLength], data[signatureLength:]
+	}
+	message.Payload = data
+
+	// Decrypt the message, if requested
+	if key == nil {
+		return message, nil
+	}
+	err = message.decrypt(key)
+	switch err {
+	case nil:
+		return message, nil
+
+	case ecies.ErrInvalidPublicKey: // Payload isn't encrypted
+		return message, err
+
+	default:
+		return nil, fmt.Errorf("unable to open envelope, decrypt failed: %v", err)
+	}
+}
+
+// Hash returns the SHA3 hash of the envelope, calculating it if not yet done.
+func (self *Envelope) Hash() common.Hash {
+	if (self.hash == common.Hash{}) {
+		enc, _ := rlp.EncodeToBytes(self)
+		self.hash = crypto.Keccak256Hash(enc)
+	}
+	return self.hash
+}
+
+// DecodeRLP decodes an Envelope from an RLP data stream.
+func (self *Envelope) DecodeRLP(s *rlp.Stream) error {
+	raw, err := s.Raw()
+	if err != nil {
+		return err
+	}
+	// The decoding of Envelope uses the struct fields but also needs
+	// to compute the hash of the whole RLP-encoded envelope. This
+	// type has the same structure as Envelope but is not an
+	// rlp.Decoder so we can reuse the Envelope struct definition.
+	type rlpenv Envelope
+	if err := rlp.DecodeBytes(raw, (*rlpenv)(self)); err != nil {
+		return err
+	}
+	self.hash = crypto.Keccak256Hash(raw)
+	return nil
+}