whisper/whisperv6: implement pow/bloom exchange protocol (#15802)

This is the main feature of v6.

whisper/whisperv6/api.go

@@ -116,12 +116,17 @@ func (api *PublicWhisperAPI) SetMaxMessageSize(ctx context.Context, size uint32)
 	return true, api.w.SetMaxMessageSize(size)
 }
 
-// SetMinPow sets the minimum PoW for a message before it is accepted.
+// SetMinPow sets the minimum PoW, and notifies the peers.
 func (api *PublicWhisperAPI) SetMinPoW(ctx context.Context, pow float64) (bool, error) {
 	return true, api.w.SetMinimumPoW(pow)
 }
 
-// MarkTrustedPeer marks a peer trusted. , which will allow it to send historic (expired) messages.
+// SetBloomFilter sets the new value of bloom filter, and notifies the peers.
+func (api *PublicWhisperAPI) SetBloomFilter(ctx context.Context, bloom hexutil.Bytes) (bool, error) {
+	return true, api.w.SetBloomFilter(bloom)
+}
+
+// MarkTrustedPeer marks a peer trusted, which will allow it to send historic (expired) messages.
 // Note: This function is not adding new nodes, the node needs to exists as a peer.
 func (api *PublicWhisperAPI) MarkTrustedPeer(ctx context.Context, enode string) (bool, error) {
 	n, err := discover.ParseNode(enode)

whisper/whisperv6/doc.go

@@ -35,7 +35,6 @@ import (
 )
 
 const (
-	EnvelopeVersion    = uint64(0)
 	ProtocolVersion    = uint64(6)
 	ProtocolVersionStr = "6.0"
 	ProtocolName       = "shh"
@@ -52,11 +51,14 @@ const (
 	paddingMask   = byte(3)
 	signatureFlag = byte(4)
 
-	TopicLength     = 4
-	signatureLength = 65
-	aesKeyLength    = 32
-	AESNonceLength  = 12
-	keyIdSize       = 32
+	TopicLength     = 4  // in bytes
+	signatureLength = 65 // in bytes
+	aesKeyLength    = 32 // in bytes
+	AESNonceLength  = 12 // in bytes
+	keyIdSize       = 32 // in bytes
+	bloomFilterSize = 64 // in bytes
+
+	EnvelopeHeaderLength = 20
 
 	MaxMessageSize        = uint32(10 * 1024 * 1024) // maximum accepted size of a message.
 	DefaultMaxMessageSize = uint32(1024 * 1024)
@@ -68,10 +70,8 @@ const (
 	expirationCycle   = time.Second
 	transmissionCycle = 300 * time.Millisecond
 
-	DefaultTTL     = 50 // seconds
-	SynchAllowance = 10 // seconds
-
-	EnvelopeHeaderLength = 20
+	DefaultTTL           = 50 // seconds
+	DefaultSyncAllowance = 10 // seconds
 )
 
 type unknownVersionError uint64

whisper/whisperv6/envelope.go

@@ -42,9 +42,11 @@ type Envelope struct {
 	Data   []byte
 	Nonce  uint64
 
-	pow  float64     // Message-specific PoW as described in the Whisper specification.
-	hash common.Hash // Cached hash of the envelope to avoid rehashing every time.
-	// Don't access hash directly, use Hash() function instead.
+	pow float64 // Message-specific PoW as described in the Whisper specification.
+
+	// the following variables should not be accessed directly, use the corresponding function instead: Hash(), Bloom()
+	hash  common.Hash // Cached hash of the envelope to avoid rehashing every time.
+	bloom []byte
 }
 
 // size returns the size of envelope as it is sent (i.e. public fields only)
@@ -227,3 +229,30 @@ func (e *Envelope) Open(watcher *Filter) (msg *ReceivedMessage) {
 	}
 	return msg
 }
+
+// Bloom maps 4-bytes Topic into 64-byte bloom filter with 3 bits set (at most).
+func (e *Envelope) Bloom() []byte {
+	if e.bloom == nil {
+		e.bloom = TopicToBloom(e.Topic)
+	}
+	return e.bloom
+}
+
+// TopicToBloom converts the topic (4 bytes) to the bloom filter (64 bytes)
+func TopicToBloom(topic TopicType) []byte {
+	b := make([]byte, bloomFilterSize)
+	var index [3]int
+	for j := 0; j < 3; j++ {
+		index[j] = int(topic[j])
+		if (topic[3] & (1 << uint(j))) != 0 {
+			index[j] += 256
+		}
+	}
+
+	for j := 0; j < 3; j++ {
+		byteIndex := index[j] / 8
+		bitIndex := index[j] % 8
+		b[byteIndex] = (1 << uint(bitIndex))
+	}
+	return b
+}

whisper/whisperv6/peer.go

@@ -36,6 +36,7 @@ type Peer struct {
 
 	trusted        bool
 	powRequirement float64
+	bloomFilter    []byte // may contain nil in case of full node
 
 	known *set.Set // Messages already known by the peer to avoid wasting bandwidth
 
@@ -74,8 +75,12 @@ func (p *Peer) handshake() error {
 	// Send the handshake status message asynchronously
 	errc := make(chan error, 1)
 	go func() {
-		errc <- p2p.Send(p.ws, statusCode, ProtocolVersion)
+		pow := p.host.MinPow()
+		powConverted := math.Float64bits(pow)
+		bloom := p.host.BloomFilter()
+		errc <- p2p.SendItems(p.ws, statusCode, ProtocolVersion, powConverted, bloom)
 	}()
+
 	// Fetch the remote status packet and verify protocol match
 	packet, err := p.ws.ReadMsg()
 	if err != nil {
@@ -85,14 +90,42 @@ func (p *Peer) handshake() error {
 		return fmt.Errorf("peer [%x] sent packet %x before status packet", p.ID(), packet.Code)
 	}
 	s := rlp.NewStream(packet.Payload, uint64(packet.Size))
-	peerVersion, err := s.Uint()
+	_, err = s.List()
 	if err != nil {
 		return fmt.Errorf("peer [%x] sent bad status message: %v", p.ID(), err)
 	}
+	peerVersion, err := s.Uint()
+	if err != nil {
+		return fmt.Errorf("peer [%x] sent bad status message (unable to decode version): %v", p.ID(), err)
+	}
 	if peerVersion != ProtocolVersion {
 		return fmt.Errorf("peer [%x]: protocol version mismatch %d != %d", p.ID(), peerVersion, ProtocolVersion)
 	}
-	// Wait until out own status is consumed too
+
+	// only version is mandatory, subsequent parameters are optional
+	powRaw, err := s.Uint()
+	if err == nil {
+		pow := math.Float64frombits(powRaw)
+		if math.IsInf(pow, 0) || math.IsNaN(pow) || pow < 0.0 {
+			return fmt.Errorf("peer [%x] sent bad status message: invalid pow", p.ID())
+		}
+		p.powRequirement = pow
+
+		var bloom []byte
+		err = s.Decode(&bloom)
+		if err == nil {
+			sz := len(bloom)
+			if sz != bloomFilterSize && sz != 0 {
+				return fmt.Errorf("peer [%x] sent bad status message: wrong bloom filter size %d", p.ID(), sz)
+			}
+			if isFullNode(bloom) {
+				p.bloomFilter = nil
+			} else {
+				p.bloomFilter = bloom
+			}
+		}
+	}
+
 	if err := <-errc; err != nil {
 		return fmt.Errorf("peer [%x] failed to send status packet: %v", p.ID(), err)
 	}
@@ -156,7 +189,7 @@ func (p *Peer) broadcast() error {
 	envelopes := p.host.Envelopes()
 	bundle := make([]*Envelope, 0, len(envelopes))
 	for _, envelope := range envelopes {
-		if !p.marked(envelope) && envelope.PoW() >= p.powRequirement {
+		if !p.marked(envelope) && envelope.PoW() >= p.powRequirement && p.bloomMatch(envelope) {
 			bundle = append(bundle, envelope)
 		}
 	}
@@ -186,3 +219,16 @@ func (p *Peer) notifyAboutPowRequirementChange(pow float64) error {
 	i := math.Float64bits(pow)
 	return p2p.Send(p.ws, powRequirementCode, i)
 }
+
+func (p *Peer) notifyAboutBloomFilterChange(bloom []byte) error {
+	return p2p.Send(p.ws, bloomFilterExCode, bloom)
+}
+
+func (p *Peer) bloomMatch(env *Envelope) bool {
+	if p.bloomFilter == nil {
+		// no filter - full node, accepts all envelops
+		return true
+	}
+
+	return bloomFilterMatch(p.bloomFilter, env.Bloom())
+}

whisper/whisperv6/peer_test.go

@@ -20,6 +20,7 @@ import (
 	"bytes"
 	"crypto/ecdsa"
 	"fmt"
+	mrand "math/rand"
 	"net"
 	"sync"
 	"testing"
@@ -87,6 +88,9 @@ var nodes [NumNodes]*TestNode
 var sharedKey []byte = []byte("some arbitrary data here")
 var sharedTopic TopicType = TopicType{0xF, 0x1, 0x2, 0}
 var expectedMessage []byte = []byte("per rectum ad astra")
+var masterBloomFilter []byte
+var masterPow = 0.00000001
+var round int = 1
 
 func TestSimulation(t *testing.T) {
 	// create a chain of whisper nodes,
@@ -104,8 +108,13 @@ func TestSimulation(t *testing.T) {
 	// check if each node have received and decrypted exactly one message
 	checkPropagation(t, true)
 
-	// send protocol-level messages (powRequirementCode) and check the new PoW requirement values
-	powReqExchange(t)
+	// check if Status message was correctly decoded
+	checkBloomFilterExchange(t)
+	checkPowExchange(t)
+
+	// send new pow and bloom exchange messages
+	resetParams(t)
+	round++
 
 	// node #1 sends one expected (decryptable) message
 	sendMsg(t, true, 1)
@@ -113,18 +122,65 @@ func TestSimulation(t *testing.T) {
 	// check if each node (except node #0) have received and decrypted exactly one message
 	checkPropagation(t, false)
 
+	for i := 1; i < NumNodes; i++ {
+		time.Sleep(20 * time.Millisecond)
+		sendMsg(t, true, i)
+	}
+
+	// check if corresponding protocol-level messages were correctly decoded
+	checkPowExchangeForNodeZero(t)
+	checkBloomFilterExchange(t)
+
 	stopServers()
 }
 
+func resetParams(t *testing.T) {
+	// change pow only for node zero
+	masterPow = 7777777.0
+	nodes[0].shh.SetMinimumPoW(masterPow)
+
+	// change bloom for all nodes
+	masterBloomFilter = TopicToBloom(sharedTopic)
+	for i := 0; i < NumNodes; i++ {
+		nodes[i].shh.SetBloomFilter(masterBloomFilter)
+	}
+}
+
+func initBloom(t *testing.T) {
+	masterBloomFilter = make([]byte, bloomFilterSize)
+	_, err := mrand.Read(masterBloomFilter)
+	if err != nil {
+		t.Fatalf("rand failed: %s.", err)
+	}
+
+	msgBloom := TopicToBloom(sharedTopic)
+	masterBloomFilter = addBloom(masterBloomFilter, msgBloom)
+	for i := 0; i < 32; i++ {
+		masterBloomFilter[i] = 0xFF
+	}
+
+	if !bloomFilterMatch(masterBloomFilter, msgBloom) {
+		t.Fatalf("bloom mismatch on initBloom.")
+	}
+}
+
 func initialize(t *testing.T) {
+	initBloom(t)
+
 	var err error
 	ip := net.IPv4(127, 0, 0, 1)
 	port0 := 30303
 
 	for i := 0; i < NumNodes; i++ {
 		var node TestNode
+		b := make([]byte, bloomFilterSize)
+		copy(b, masterBloomFilter)
 		node.shh = New(&DefaultConfig)
-		node.shh.SetMinimumPowTest(0.00000001)
+		node.shh.SetMinimumPoW(masterPow)
+		node.shh.SetBloomFilter(b)
+		if !bytes.Equal(node.shh.BloomFilter(), masterBloomFilter) {
+			t.Fatalf("bloom mismatch on init.")
+		}
 		node.shh.Start(nil)
 		topics := make([]TopicType, 0)
 		topics = append(topics, sharedTopic)
@@ -206,7 +262,7 @@ func checkPropagation(t *testing.T, includingNodeZero bool) {
 		for i := first; i < NumNodes; i++ {
 			f := nodes[i].shh.GetFilter(nodes[i].filerId)
 			if f == nil {
-				t.Fatalf("failed to get filterId %s from node %d.", nodes[i].filerId, i)
+				t.Fatalf("failed to get filterId %s from node %d, round %d.", nodes[i].filerId, i, round)
 			}
 
 			mail := f.Retrieve()
@@ -332,34 +388,43 @@ func TestPeerBasic(t *testing.T) {
 	}
 }
 
-func powReqExchange(t *testing.T) {
+func checkPowExchangeForNodeZero(t *testing.T) {
+	cnt := 0
 	for i, node := range nodes {
 		for peer := range node.shh.peers {
-			if peer.powRequirement > 1000.0 {
-				t.Fatalf("node %d: one of the peers' pow requirement is too big (%f).", i, peer.powRequirement)
+			if peer.peer.ID() == discover.PubkeyID(&nodes[0].id.PublicKey) {
+				cnt++
+				if peer.powRequirement != masterPow {
+					t.Fatalf("node %d: failed to set the new pow requirement.", i)
+				}
 			}
 		}
 	}
+	if cnt == 0 {
+		t.Fatalf("no matching peers found.")
+	}
+}
 
-	const pow float64 = 7777777.0
-	nodes[0].shh.SetMinimumPoW(pow)
-
-	// wait until all the messages are delivered
-	time.Sleep(64 * time.Millisecond)
-
-	cnt := 0
+func checkPowExchange(t *testing.T) {
 	for i, node := range nodes {
 		for peer := range node.shh.peers {
-			if peer.peer.ID() == discover.PubkeyID(&nodes[0].id.PublicKey) {
-				cnt++
-				if peer.powRequirement != pow {
-					t.Fatalf("node %d: failed to set the new pow requirement.", i)
+			if peer.peer.ID() != discover.PubkeyID(&nodes[0].id.PublicKey) {
+				if peer.powRequirement != masterPow {
+					t.Fatalf("node %d: failed to exchange pow requirement in round %d; expected %f, got %f",
+						i, round, masterPow, peer.powRequirement)
 				}
 			}
 		}
 	}
+}
 
-	if cnt == 0 {
-		t.Fatalf("no matching peers found.")
+func checkBloomFilterExchange(t *testing.T) {
+	for i, node := range nodes {
+		for peer := range node.shh.peers {
+			if !bytes.Equal(peer.bloomFilter, masterBloomFilter) {
+				t.Fatalf("node %d: failed to exchange bloom filter requirement in round %d. \n%x expected \n%x got",
+					i, round, masterBloomFilter, peer.bloomFilter)
+			}
+		}
 	}
 }

whisper/whisperv6/whisper_test.go

@@ -843,3 +843,64 @@ func TestSymmetricSendKeyMismatch(t *testing.T) {
 		t.Fatalf("received a message when keys weren't matching")
 	}
 }
+
+func TestBloom(t *testing.T) {
+	topic := TopicType{0, 0, 255, 6}
+	b := TopicToBloom(topic)
+	x := make([]byte, bloomFilterSize)
+	x[0] = byte(1)
+	x[32] = byte(1)
+	x[bloomFilterSize-1] = byte(128)
+	if !bloomFilterMatch(x, b) || !bloomFilterMatch(b, x) {
+		t.Fatalf("bloom filter does not match the mask")
+	}
+
+	_, err := mrand.Read(b)
+	if err != nil {
+		t.Fatalf("math rand error")
+	}
+	_, err = mrand.Read(x)
+	if err != nil {
+		t.Fatalf("math rand error")
+	}
+	if !bloomFilterMatch(b, b) {
+		t.Fatalf("bloom filter does not match self")
+	}
+	x = addBloom(x, b)
+	if !bloomFilterMatch(x, b) {
+		t.Fatalf("bloom filter does not match combined bloom")
+	}
+	if !isFullNode(nil) {
+		t.Fatalf("isFullNode did not recognize nil as full node")
+	}
+	x[17] = 254
+	if isFullNode(x) {
+		t.Fatalf("isFullNode false positive")
+	}
+	for i := 0; i < bloomFilterSize; i++ {
+		b[i] = byte(255)
+	}
+	if !isFullNode(b) {
+		t.Fatalf("isFullNode false negative")
+	}
+	if bloomFilterMatch(x, b) {
+		t.Fatalf("bloomFilterMatch false positive")
+	}
+	if !bloomFilterMatch(b, x) {
+		t.Fatalf("bloomFilterMatch false negative")
+	}
+
+	w := New(&DefaultConfig)
+	f := w.BloomFilter()
+	if f != nil {
+		t.Fatalf("wrong bloom on creation")
+	}
+	err = w.SetBloomFilter(x)
+	if err != nil {
+		t.Fatalf("failed to set bloom filter: %s", err)
+	}
+	f = w.BloomFilter()
+	if !bloomFilterMatch(f, x) || !bloomFilterMatch(x, f) {
+		t.Fatalf("retireved wrong bloom filter")
+	}
+}