swarm/pss: refactoring

swarm/pss/keystore.go

@@ -0,0 +1,281 @@
+// Copyright 2019 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 pss
+
+import (
+	"crypto/ecdsa"
+	"errors"
+	"fmt"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/metrics"
+	"github.com/ethereum/go-ethereum/swarm/log"
+	whisper "github.com/ethereum/go-ethereum/whisper/whisperv6"
+)
+
+type KeyStore struct {
+	w *whisper.Whisper // key and encryption backend
+
+	mx                       sync.RWMutex
+	pubKeyPool               map[string]map[Topic]*pssPeer // mapping of hex public keys to peer address by topic.
+	symKeyPool               map[string]map[Topic]*pssPeer // mapping of symkeyids to peer address by topic.
+	symKeyDecryptCache       []*string                     // fast lookup of symkeys recently used for decryption; last used is on top of stack
+	symKeyDecryptCacheCursor int                           // modular cursor pointing to last used, wraps on symKeyDecryptCache array
+}
+
+func loadKeyStore() *KeyStore {
+	return &KeyStore{
+		w: whisper.New(&whisper.DefaultConfig),
+
+		pubKeyPool:         make(map[string]map[Topic]*pssPeer),
+		symKeyPool:         make(map[string]map[Topic]*pssPeer),
+		symKeyDecryptCache: make([]*string, defaultSymKeyCacheCapacity),
+	}
+}
+
+func (ks *KeyStore) isSymKeyStored(key string) bool {
+	ks.mx.RLock()
+	defer ks.mx.RUnlock()
+	var ok bool
+	_, ok = ks.symKeyPool[key]
+	return ok
+}
+
+func (ks *KeyStore) isPubKeyStored(key string) bool {
+	ks.mx.RLock()
+	defer ks.mx.RUnlock()
+	var ok bool
+	_, ok = ks.pubKeyPool[key]
+	return ok
+}
+
+func (ks *KeyStore) getPeerSym(symkeyid string, topic Topic) (*pssPeer, bool) {
+	ks.mx.RLock()
+	defer ks.mx.RUnlock()
+	psp, ok := ks.symKeyPool[symkeyid][topic]
+	return psp, ok
+}
+
+func (ks *KeyStore) getPeerPub(pubkeyid string, topic Topic) (*pssPeer, bool) {
+	ks.mx.RLock()
+	defer ks.mx.RUnlock()
+	psp, ok := ks.pubKeyPool[pubkeyid][topic]
+	return psp, ok
+}
+
+// Links a peer ECDSA public key to a topic.
+// This is required for asymmetric message exchange on the given topic.
+// The value in `address` will be used as a routing hint for the public key / topic association.
+func (ks *KeyStore) SetPeerPublicKey(pubkey *ecdsa.PublicKey, topic Topic, address PssAddress) error {
+	if err := validateAddress(address); err != nil {
+		return err
+	}
+	pubkeybytes := crypto.FromECDSAPub(pubkey)
+	if len(pubkeybytes) == 0 {
+		return fmt.Errorf("invalid public key: %v", pubkey)
+	}
+	pubkeyid := common.ToHex(pubkeybytes)
+	psp := &pssPeer{
+		address: address,
+	}
+	ks.mx.Lock()
+	if _, ok := ks.pubKeyPool[pubkeyid]; !ok {
+		ks.pubKeyPool[pubkeyid] = make(map[Topic]*pssPeer)
+	}
+	ks.pubKeyPool[pubkeyid][topic] = psp
+	ks.mx.Unlock()
+	log.Trace("added pubkey", "pubkeyid", pubkeyid, "topic", topic, "address", address)
+	return nil
+}
+
+// adds a symmetric key to the pss key pool, and optionally adds the key to the
+// collection of keys used to attempt symmetric decryption of incoming messages
+func (ks *KeyStore) addSymmetricKeyToPool(keyid string, topic Topic, address PssAddress, addtocache bool, protected bool) {
+	psp := &pssPeer{
+		address:   address,
+		protected: protected,
+	}
+	ks.mx.Lock()
+	if _, ok := ks.symKeyPool[keyid]; !ok {
+		ks.symKeyPool[keyid] = make(map[Topic]*pssPeer)
+	}
+	ks.symKeyPool[keyid][topic] = psp
+	ks.mx.Unlock()
+	if addtocache {
+		ks.symKeyDecryptCacheCursor++
+		ks.symKeyDecryptCache[ks.symKeyDecryptCacheCursor%cap(ks.symKeyDecryptCache)] = &keyid
+	}
+}
+
+// Returns all recorded topic and address combination for a specific public key
+func (ks *KeyStore) GetPublickeyPeers(keyid string) (topic []Topic, address []PssAddress, err error) {
+	ks.mx.RLock()
+	defer ks.mx.RUnlock()
+	for t, peer := range ks.pubKeyPool[keyid] {
+		topic = append(topic, t)
+		address = append(address, peer.address)
+	}
+	return topic, address, nil
+}
+
+func (ks *KeyStore) getPeerAddress(keyid string, topic Topic) (PssAddress, error) {
+	ks.mx.RLock()
+	defer ks.mx.RUnlock()
+	if peers, ok := ks.pubKeyPool[keyid]; ok {
+		if t, ok := peers[topic]; ok {
+			return t.address, nil
+		}
+	}
+	return nil, fmt.Errorf("peer with pubkey %s, topic %x not found", keyid, topic)
+}
+
+// Attempt to decrypt, validate and unpack a symmetrically encrypted message.
+// If successful, returns the unpacked whisper ReceivedMessage struct
+// encapsulating the decrypted message, and the whisper backend id
+// of the symmetric key used to decrypt the message.
+// It fails if decryption of the message fails or if the message is corrupted.
+func (ks *KeyStore) processSym(envelope *whisper.Envelope) (*whisper.ReceivedMessage, string, PssAddress, error) {
+	metrics.GetOrRegisterCounter("pss.process.sym", nil).Inc(1)
+
+	for i := ks.symKeyDecryptCacheCursor; i > ks.symKeyDecryptCacheCursor-cap(ks.symKeyDecryptCache) && i > 0; i-- {
+		symkeyid := ks.symKeyDecryptCache[i%cap(ks.symKeyDecryptCache)]
+		symkey, err := ks.w.GetSymKey(*symkeyid)
+		if err != nil {
+			continue
+		}
+		recvmsg, err := envelope.OpenSymmetric(symkey)
+		if err != nil {
+			continue
+		}
+		if !recvmsg.ValidateAndParse() {
+			return nil, "", nil, errors.New("symmetrically encrypted message has invalid signature or is corrupt")
+		}
+		var from PssAddress
+		ks.mx.RLock()
+		if ks.symKeyPool[*symkeyid][Topic(envelope.Topic)] != nil {
+			from = ks.symKeyPool[*symkeyid][Topic(envelope.Topic)].address
+		}
+		ks.mx.RUnlock()
+		ks.symKeyDecryptCacheCursor++
+		ks.symKeyDecryptCache[ks.symKeyDecryptCacheCursor%cap(ks.symKeyDecryptCache)] = symkeyid
+		return recvmsg, *symkeyid, from, nil
+	}
+	return nil, "", nil, errors.New("could not decrypt message")
+}
+
+// Attempt to decrypt, validate and unpack an asymmetrically encrypted message.
+// If successful, returns the unpacked whisper ReceivedMessage struct
+// encapsulating the decrypted message, and the byte representation of
+// the public key used to decrypt the message.
+// It fails if decryption of message fails, or if the message is corrupted.
+func (ks *Pss) processAsym(envelope *whisper.Envelope) (*whisper.ReceivedMessage, string, PssAddress, error) {
+	metrics.GetOrRegisterCounter("pss.process.asym", nil).Inc(1)
+
+	recvmsg, err := envelope.OpenAsymmetric(ks.privateKey)
+	if err != nil {
+		return nil, "", nil, fmt.Errorf("could not decrypt message: %s", err)
+	}
+	// check signature (if signed), strip padding
+	if !recvmsg.ValidateAndParse() {
+		return nil, "", nil, errors.New("invalid message")
+	}
+	pubkeyid := common.ToHex(crypto.FromECDSAPub(recvmsg.Src))
+	var from PssAddress
+	ks.mx.RLock()
+	if ks.pubKeyPool[pubkeyid][Topic(envelope.Topic)] != nil {
+		from = ks.pubKeyPool[pubkeyid][Topic(envelope.Topic)].address
+	}
+	ks.mx.RUnlock()
+	return recvmsg, pubkeyid, from, nil
+}
+
+// Symkey garbage collection
+// a key is removed if:
+// - it is not marked as protected
+// - it is not in the incoming decryption cache
+func (ks *Pss) cleanKeys() (count int) {
+	for keyid, peertopics := range ks.symKeyPool {
+		var expiredtopics []Topic
+		for topic, psp := range peertopics {
+			if psp.protected {
+				continue
+			}
+
+			var match bool
+			for i := ks.symKeyDecryptCacheCursor; i > ks.symKeyDecryptCacheCursor-cap(ks.symKeyDecryptCache) && i > 0; i-- {
+				cacheid := ks.symKeyDecryptCache[i%cap(ks.symKeyDecryptCache)]
+				if *cacheid == keyid {
+					match = true
+				}
+			}
+			if !match {
+				expiredtopics = append(expiredtopics, topic)
+			}
+		}
+		for _, topic := range expiredtopics {
+			ks.mx.Lock()
+			delete(ks.symKeyPool[keyid], topic)
+			log.Trace("symkey cleanup deletion", "symkeyid", keyid, "topic", topic, "val", ks.symKeyPool[keyid])
+			ks.mx.Unlock()
+			count++
+		}
+	}
+	return count
+}
+
+// Automatically generate a new symkey for a topic and address hint
+func (ks *KeyStore) GenerateSymmetricKey(topic Topic, address PssAddress, addToCache bool) (string, error) {
+	keyid, err := ks.w.GenerateSymKey()
+	if err == nil {
+		ks.addSymmetricKeyToPool(keyid, topic, address, addToCache, false)
+	}
+	return keyid, err
+}
+
+// Returns a symmetric key byte sequence stored in the whisper backend by its unique id.
+// Passes on the error value from the whisper backend.
+func (ks *KeyStore) GetSymmetricKey(symkeyid string) ([]byte, error) {
+	return ks.w.GetSymKey(symkeyid)
+}
+
+// Links a peer symmetric key (arbitrary byte sequence) to a topic.
+//
+// This is required for symmetrically encrypted message exchange on the given topic.
+//
+// The key is stored in the whisper backend.
+//
+// If addtocache is set to true, the key will be added to the cache of keys
+// used to attempt symmetric decryption of incoming messages.
+//
+// Returns a string id that can be used to retrieve the key bytes
+// from the whisper backend (see pss.GetSymmetricKey())
+func (ks *KeyStore) SetSymmetricKey(key []byte, topic Topic, address PssAddress, addtocache bool) (string, error) {
+	if err := validateAddress(address); err != nil {
+		return "", err
+	}
+	return ks.setSymmetricKey(key, topic, address, addtocache, true)
+}
+
+func (ks *KeyStore) setSymmetricKey(key []byte, topic Topic, address PssAddress, addtocache bool, protected bool) (string, error) {
+	keyid, err := ks.w.AddSymKeyDirect(key)
+	if err == nil {
+		ks.addSymmetricKeyToPool(keyid, topic, address, addtocache, protected)
+	}
+	return keyid, err
+}

swarm/pss/protocol.go

@@ -228,7 +228,6 @@ func ToP2pMsg(msg []byte) (p2p.Msg, error) {
 // to link the peer to.
 // The key must exist in the pss store prior to adding the peer.
 func (p *Protocol) AddPeer(peer *p2p.Peer, topic Topic, asymmetric bool, key string) (p2p.MsgReadWriter, error) {
-	var ok bool
 	rw := &PssReadWriter{
 		Pss:   p.Pss,
 		rw:    make(chan p2p.Msg),
@@ -242,20 +241,14 @@ func (p *Protocol) AddPeer(peer *p2p.Peer, topic Topic, asymmetric bool, key str
 		rw.sendFunc = p.Pss.SendSym
 	}
 	if asymmetric {
-		p.Pss.pubKeyPoolMu.Lock()
-		_, ok = p.Pss.pubKeyPool[key]
-		p.Pss.pubKeyPoolMu.Unlock()
-		if !ok {
+		if !p.Pss.isPubKeyStored(key) {
 			return nil, fmt.Errorf("asym key does not exist: %s", key)
 		}
 		p.RWPoolMu.Lock()
 		p.pubKeyRWPool[key] = rw
 		p.RWPoolMu.Unlock()
 	} else {
-		p.Pss.symKeyPoolMu.Lock()
-		_, ok = p.Pss.symKeyPool[key]
-		p.Pss.symKeyPoolMu.Unlock()
-		if !ok {
+		if !p.Pss.isSymKeyStored(key) {
 			return nil, fmt.Errorf("symkey does not exist: %s", key)
 		}
 		p.RWPoolMu.Lock()