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// Copyright 2016 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 whisperv5
import (
"crypto/ecdsa"
"fmt"
"sync"
"github.com/dexon-foundation/dexon/common"
"github.com/dexon-foundation/dexon/crypto"
"github.com/dexon-foundation/dexon/log"
)
type Filter struct {
Src *ecdsa.PublicKey // Sender of the message
KeyAsym *ecdsa.PrivateKey // Private Key of recipient
KeySym []byte // Key associated with the Topic
Topics [][]byte // Topics to filter messages with
PoW float64 // Proof of work as described in the Whisper spec
AllowP2P bool // Indicates whether this filter is interested in direct peer-to-peer messages
SymKeyHash common.Hash // The Keccak256Hash of the symmetric key, needed for optimization
Messages map[common.Hash]*ReceivedMessage
mutex sync.RWMutex
}
type Filters struct {
watchers map[string]*Filter
whisper *Whisper
mutex sync.RWMutex
}
func NewFilters(w *Whisper) *Filters {
return &Filters{
watchers: make(map[string]*Filter),
whisper: w,
}
}
func (fs *Filters) Install(watcher *Filter) (string, error) {
if watcher.Messages == nil {
watcher.Messages = make(map[common.Hash]*ReceivedMessage)
}
id, err := GenerateRandomID()
if err != nil {
return "", err
}
fs.mutex.Lock()
defer fs.mutex.Unlock()
if fs.watchers[id] != nil {
return "", fmt.Errorf("failed to generate unique ID")
}
if watcher.expectsSymmetricEncryption() {
watcher.SymKeyHash = crypto.Keccak256Hash(watcher.KeySym)
}
fs.watchers[id] = watcher
return id, err
}
func (fs *Filters) Uninstall(id string) bool {
fs.mutex.Lock()
defer fs.mutex.Unlock()
if fs.watchers[id] != nil {
delete(fs.watchers, id)
return true
}
return false
}
func (fs *Filters) Get(id string) *Filter {
fs.mutex.RLock()
defer fs.mutex.RUnlock()
return fs.watchers[id]
}
func (fs *Filters) NotifyWatchers(env *Envelope, p2pMessage bool) {
var msg *ReceivedMessage
fs.mutex.RLock()
defer fs.mutex.RUnlock()
i := -1 // only used for logging info
for _, watcher := range fs.watchers {
i++
if p2pMessage && !watcher.AllowP2P {
log.Trace(fmt.Sprintf("msg [%x], filter [%d]: p2p messages are not allowed", env.Hash(), i))
continue
}
var match bool
if msg != nil {
match = watcher.MatchMessage(msg)
} else {
match = watcher.MatchEnvelope(env)
if match {
msg = env.Open(watcher)
if msg == nil {
log.Trace("processing message: failed to open", "message", env.Hash().Hex(), "filter", i)
}
} else {
log.Trace("processing message: does not match", "message", env.Hash().Hex(), "filter", i)
}
}
if match && msg != nil {
log.Trace("processing message: decrypted", "hash", env.Hash().Hex())
if watcher.Src == nil || IsPubKeyEqual(msg.Src, watcher.Src) {
watcher.Trigger(msg)
}
}
}
}
func (f *Filter) processEnvelope(env *Envelope) *ReceivedMessage {
if f.MatchEnvelope(env) {
msg := env.Open(f)
if msg != nil {
return msg
} else {
log.Trace("processing envelope: failed to open", "hash", env.Hash().Hex())
}
} else {
log.Trace("processing envelope: does not match", "hash", env.Hash().Hex())
}
return nil
}
func (f *Filter) expectsAsymmetricEncryption() bool {
return f.KeyAsym != nil
}
func (f *Filter) expectsSymmetricEncryption() bool {
return f.KeySym != nil
}
func (f *Filter) Trigger(msg *ReceivedMessage) {
f.mutex.Lock()
defer f.mutex.Unlock()
if _, exist := f.Messages[msg.EnvelopeHash]; !exist {
f.Messages[msg.EnvelopeHash] = msg
}
}
func (f *Filter) Retrieve() (all []*ReceivedMessage) {
f.mutex.Lock()
defer f.mutex.Unlock()
all = make([]*ReceivedMessage, 0, len(f.Messages))
for _, msg := range f.Messages {
all = append(all, msg)
}
f.Messages = make(map[common.Hash]*ReceivedMessage) // delete old messages
return all
}
func (f *Filter) MatchMessage(msg *ReceivedMessage) bool {
if f.PoW > 0 && msg.PoW < f.PoW {
return false
}
if f.expectsAsymmetricEncryption() && msg.isAsymmetricEncryption() {
return IsPubKeyEqual(&f.KeyAsym.PublicKey, msg.Dst) && f.MatchTopic(msg.Topic)
} else if f.expectsSymmetricEncryption() && msg.isSymmetricEncryption() {
return f.SymKeyHash == msg.SymKeyHash && f.MatchTopic(msg.Topic)
}
return false
}
func (f *Filter) MatchEnvelope(envelope *Envelope) bool {
if f.PoW > 0 && envelope.pow < f.PoW {
return false
}
if f.expectsAsymmetricEncryption() && envelope.isAsymmetric() {
return f.MatchTopic(envelope.Topic)
} else if f.expectsSymmetricEncryption() && envelope.IsSymmetric() {
return f.MatchTopic(envelope.Topic)
}
return false
}
func (f *Filter) MatchTopic(topic TopicType) bool {
if len(f.Topics) == 0 {
// any topic matches
return true
}
for _, bt := range f.Topics {
if matchSingleTopic(topic, bt) {
return true
}
}
return false
}
func matchSingleTopic(topic TopicType, bt []byte) bool {
if len(bt) > TopicLength {
bt = bt[:TopicLength]
}
if len(bt) == 0 {
return false
}
for j, b := range bt {
if topic[j] != b {
return false
}
}
return true
}
func IsPubKeyEqual(a, b *ecdsa.PublicKey) bool {
if !ValidatePublicKey(a) {
return false
} else if !ValidatePublicKey(b) {
return false
}
// the curve is always the same, just compare the points
return a.X.Cmp(b.X) == 0 && a.Y.Cmp(b.Y) == 0
}
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