whisper: minor refactoring

whisper/whisperv6/doc.go

@@ -51,12 +51,12 @@ const (
 	paddingMask   = byte(3)
 	signatureFlag = byte(4)
 
-	TopicLength     = 4
-	signatureLength = 65
-	aesKeyLength    = 32
-	AESNonceLength  = 12
-	keyIdSize       = 32
-	bloomFilterSize = 64
+	TopicLength     = 4  // in bytes
+	signatureLength = 65 // in bytes
+	aesKeyLength    = 32 // in bytes
+	AESNonceLength  = 12 // in bytes
+	keyIdSize       = 32 // in bytes
+	bloomFilterSize = 64 // in bytes
 
 	MaxMessageSize        = uint32(10 * 1024 * 1024) // maximum accepted size of a message.
 	DefaultMaxMessageSize = uint32(1024 * 1024)
@@ -70,8 +70,6 @@ const (
 
 	DefaultTTL           = 50 // seconds
 	DefaultSyncAllowance = 10 // seconds
-
-	EnvelopeHeaderLength = 20
 )
 
 type unknownVersionError uint64

whisper/whisperv6/envelope.go

@@ -51,6 +51,7 @@ type Envelope struct {
 
 // size returns the size of envelope as it is sent (i.e. public fields only)
 func (e *Envelope) size() int {
+	const EnvelopeHeaderLength = 20
 	return EnvelopeHeaderLength + len(e.Data)
 }
 
@@ -238,13 +239,13 @@ func (e *Envelope) Bloom() []byte {
 	return e.bloom
 }
 
+// TopicToBloom converts the topic (4 bytes) to the bloom filter (64 bytes)
 func TopicToBloom(topic TopicType) []byte {
-	var powers = [...]byte{1, 2, 4, 8, 16, 32, 64, 128}
 	b := make([]byte, bloomFilterSize)
 	var index [3]int
 	for j := 0; j < 3; j++ {
 		index[j] = int(topic[j])
-		if (topic[3] & powers[j]) != 0 {
+		if (topic[3] & (1 << uint(j))) != 0 {
 			index[j] += 256
 		}
 	}
@@ -252,7 +253,7 @@ func TopicToBloom(topic TopicType) []byte {
 	for j := 0; j < 3; j++ {
 		byteIndex := index[j] / 8
 		bitIndex := index[j] % 8
-		b[byteIndex] = powers[bitIndex]
+		b[byteIndex] = (1 << uint(bitIndex))
 	}
 	return b
 }

whisper/whisperv6/peer_test.go

@@ -428,12 +428,3 @@ func checkBloomFilterExchange(t *testing.T) {
 		}
 	}
 }
-
-func isBloomFilterEqual(a, b []byte) bool {
-	for i := 0; i < bloomFilterSize; i++ {
-		if a[i] != b[i] {
-			return false
-		}
-	}
-	return true
-}

whisper/whisperv6/whisper.go

@@ -49,11 +49,11 @@ type Statistics struct {
 
 const (
 	maxMsgSizeIdx           = iota // Maximal message length allowed by the whisper node
-	overflowIdx             = iota // Indicator of message queue overflow
-	minPowIdx               = iota // Minimal PoW required by the whisper node
-	minPowToleranceIdx      = iota // Minimal PoW tolerated by the whisper node for a limited time
-	bloomFilterIdx          = iota // Bloom filter for topics of interest for this node
-	bloomFilterToleranceIdx = iota // Bloom filter tolerated by the whisper node for a limited time
+	overflowIdx                    // Indicator of message queue overflow
+	minPowIdx                      // Minimal PoW required by the whisper node
+	minPowToleranceIdx             // Minimal PoW tolerated by the whisper node for a limited time
+	bloomFilterIdx                 // Bloom filter for topics of interest for this node
+	bloomFilterToleranceIdx        // Bloom filter tolerated by the whisper node for a limited time
 )
 
 // Whisper represents a dark communication interface through the Ethereum
@@ -129,14 +129,23 @@ func New(cfg *Config) *Whisper {
 	return whisper
 }
 
+// MinPow returns the PoW value required by this node.
 func (w *Whisper) MinPow() float64 {
 	val, exist := w.settings.Load(minPowIdx)
 	if !exist || val == nil {
 		return DefaultMinimumPoW
 	}
-	return val.(float64)
+	v, ok := val.(float64)
+	if !ok {
+		log.Error("Error loading minPowIdx, using default")
+		return DefaultMinimumPoW
+	}
+	return v
 }
 
+// MinPowTolerance returns the value of minimum PoW which is tolerated for a limited
+// time after PoW was changed. If sufficient time have elapsed or no change of PoW
+// have ever occurred, the return value will be the same as return value of MinPow().
 func (w *Whisper) MinPowTolerance() float64 {
 	val, exist := w.settings.Load(minPowToleranceIdx)
 	if !exist || val == nil {
@@ -145,6 +154,10 @@ func (w *Whisper) MinPowTolerance() float64 {
 	return val.(float64)
 }
 
+// BloomFilter returns the aggregated bloom filter for all the topics of interest.
+// The nodes are required to send only messages that match the advertised bloom filter.
+// If a message does not match the bloom, it will tantamount to spam, and the peer will
+// be disconnected.
 func (w *Whisper) BloomFilter() []byte {
 	val, exist := w.settings.Load(bloomFilterIdx)
 	if !exist || val == nil {
@@ -153,6 +166,10 @@ func (w *Whisper) BloomFilter() []byte {
 	return val.([]byte)
 }
 
+// BloomFilterTolerance returns the bloom filter which is tolerated for a limited
+// time after new bloom was advertised to the peers. If sufficient time have elapsed
+// or no change of bloom filter have ever occurred, the return value will be the same
+// as return value of BloomFilter().
 func (w *Whisper) BloomFilterTolerance() []byte {
 	val, exist := w.settings.Load(bloomFilterToleranceIdx)
 	if !exist || val == nil {
@@ -1035,7 +1052,7 @@ func bloomFilterMatch(filter, sample []byte) bool {
 	for i := 0; i < bloomFilterSize; i++ {
 		f := filter[i]
 		s := sample[i]
-		if ((f | s) ^ f) != 0 {
+		if (f | s) != f {
 			return false
 		}
 	}
@@ -1050,3 +1067,12 @@ func addBloom(a, b []byte) []byte {
 	}
 	return c
 }
+
+func isBloomFilterEqual(a, b []byte) bool {
+	for i := 0; i < bloomFilterSize; i++ {
+		if a[i] != b[i] {
+			return false
+		}
+	}
+	return true
+}