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// Copyright 2017 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/>.
// Package mailserver provides a naive, example mailserver implementation
package mailserver
import (
"encoding/binary"
"fmt"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/crypto"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rlp"
whisper "github.com/ethereum/go-ethereum/whisper/whisperv6"
"github.com/syndtr/goleveldb/leveldb"
"github.com/syndtr/goleveldb/leveldb/opt"
"github.com/syndtr/goleveldb/leveldb/util"
)
// WMailServer represents the state data of the mailserver.
type WMailServer struct {
db *leveldb.DB
w *whisper.Whisper
pow float64
key []byte
}
type DBKey struct {
timestamp uint32
hash common.Hash
raw []byte
}
// NewDbKey is a helper function that creates a levelDB
// key from a hash and an integer.
func NewDbKey(t uint32, h common.Hash) *DBKey {
const sz = common.HashLength + 4
var k DBKey
k.timestamp = t
k.hash = h
k.raw = make([]byte, sz)
binary.BigEndian.PutUint32(k.raw, k.timestamp)
copy(k.raw[4:], k.hash[:])
return &k
}
// Init initializes the mail server.
func (s *WMailServer) Init(shh *whisper.Whisper, path string, password string, pow float64) error {
var err error
if len(path) == 0 {
return fmt.Errorf("DB file is not specified")
}
if len(password) == 0 {
return fmt.Errorf("password is not specified")
}
s.db, err = leveldb.OpenFile(path, &opt.Options{OpenFilesCacheCapacity: 32})
if err != nil {
return fmt.Errorf("open DB file: %s", err)
}
s.w = shh
s.pow = pow
MailServerKeyID, err := s.w.AddSymKeyFromPassword(password)
if err != nil {
return fmt.Errorf("create symmetric key: %s", err)
}
s.key, err = s.w.GetSymKey(MailServerKeyID)
if err != nil {
return fmt.Errorf("save symmetric key: %s", err)
}
return nil
}
// Close cleans up before shutdown.
func (s *WMailServer) Close() {
if s.db != nil {
s.db.Close()
}
}
// Archive stores the
func (s *WMailServer) Archive(env *whisper.Envelope) {
key := NewDbKey(env.Expiry-env.TTL, env.Hash())
rawEnvelope, err := rlp.EncodeToBytes(env)
if err != nil {
log.Error(fmt.Sprintf("rlp.EncodeToBytes failed: %s", err))
} else {
err = s.db.Put(key.raw, rawEnvelope, nil)
if err != nil {
log.Error(fmt.Sprintf("Writing to DB failed: %s", err))
}
}
}
// DeliverMail responds with saved messages upon request by the
// messages' owner.
func (s *WMailServer) DeliverMail(peer *whisper.Peer, request *whisper.Envelope) {
if peer == nil {
log.Error("Whisper peer is nil")
return
}
ok, lower, upper, bloom := s.validateRequest(peer.ID(), request)
if ok {
s.processRequest(peer, lower, upper, bloom)
}
}
func (s *WMailServer) processRequest(peer *whisper.Peer, lower, upper uint32, bloom []byte) []*whisper.Envelope {
ret := make([]*whisper.Envelope, 0)
var err error
var zero common.Hash
kl := NewDbKey(lower, zero)
ku := NewDbKey(upper+1, zero) // LevelDB is exclusive, while the Whisper API is inclusive
i := s.db.NewIterator(&util.Range{Start: kl.raw, Limit: ku.raw}, nil)
defer i.Release()
for i.Next() {
var envelope whisper.Envelope
err = rlp.DecodeBytes(i.Value(), &envelope)
if err != nil {
log.Error(fmt.Sprintf("RLP decoding failed: %s", err))
}
if whisper.BloomFilterMatch(bloom, envelope.Bloom()) {
if peer == nil {
// used for test purposes
ret = append(ret, &envelope)
} else {
err = s.w.SendP2PDirect(peer, &envelope)
if err != nil {
log.Error(fmt.Sprintf("Failed to send direct message to peer: %s", err))
return nil
}
}
}
}
err = i.Error()
if err != nil {
log.Error(fmt.Sprintf("Level DB iterator error: %s", err))
}
return ret
}
func (s *WMailServer) validateRequest(peerID []byte, request *whisper.Envelope) (bool, uint32, uint32, []byte) {
if s.pow > 0.0 && request.PoW() < s.pow {
return false, 0, 0, nil
}
f := whisper.Filter{KeySym: s.key}
decrypted := request.Open(&f)
if decrypted == nil {
log.Warn(fmt.Sprintf("Failed to decrypt p2p request"))
return false, 0, 0, nil
}
src := crypto.FromECDSAPub(decrypted.Src)
if len(src)-len(peerID) == 1 {
src = src[1:]
}
// if you want to check the signature, you can do it here. e.g.:
// if !bytes.Equal(peerID, src) {
if src == nil {
log.Warn(fmt.Sprintf("Wrong signature of p2p request"))
return false, 0, 0, nil
}
var bloom []byte
payloadSize := len(decrypted.Payload)
if payloadSize < 8 {
log.Warn(fmt.Sprintf("Undersized p2p request"))
return false, 0, 0, nil
} else if payloadSize == 8 {
bloom = whisper.MakeFullNodeBloom()
} else if payloadSize < 8+whisper.BloomFilterSize {
log.Warn(fmt.Sprintf("Undersized bloom filter in p2p request"))
return false, 0, 0, nil
} else {
bloom = decrypted.Payload[8 : 8+whisper.BloomFilterSize]
}
lower := binary.BigEndian.Uint32(decrypted.Payload[:4])
upper := binary.BigEndian.Uint32(decrypted.Payload[4:8])
return true, lower, upper, bloom
}
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