path: root/whisper/mailserver/mailserver.go

// 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
}