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

This is the main feature of v6.

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")
+	}
+}