eth: initial implementation of peer blacklist

eth/blacklist.go

@@ -0,0 +1,114 @@
+package eth
+
+import (
+	"container/heap"
+	"sync"
+	"time"
+)
+
+// Implements the heap.Interface for *BlackListPeer based on LastSeen
+type PeerHeap []*BlackListPeer
+
+func (h PeerHeap) Len() int           { return len(h) }
+func (h PeerHeap) Less(i, j int) bool { return h[i].LastSeen.Before(h[j].LastSeen) }
+func (h PeerHeap) Swap(i, j int)      { h[i], h[j] = h[j], h[i]; h[i].index = i; h[j].index = j }
+
+func (h *PeerHeap) Push(x interface{}) {
+	n := len(*h)
+	item := x.(*BlackListPeer)
+	item.index = n
+	*h = append(*h, item)
+}
+
+func (h *PeerHeap) Pop() interface{} {
+	old := *h
+	n := len(old)
+	item := old[n-1]
+	item.index = -1 // for safety
+	*h = old[0 : n-1]
+	return item
+}
+
+// Peer represents the state of a peer in the network.
+type BlackListPeer struct {
+	ID             string    // Unique identifier for the peer
+	HeadBlock      int64     // Current head block of the peer
+	LastSeen       time.Time // Timestamp of the last head block update
+	BlacklistCount int       // Counter for failed head block updates
+	index          int       // Index of the peer in the heap
+}
+
+// blackList manages peers, both active and blacklisted.
+type blackList struct {
+	mu               sync.Mutex // To handle concurrent access
+	peers            map[string]*BlackListPeer
+	peerHeap         PeerHeap
+	maxPeers         int
+	expiryTime       time.Duration
+	blacklistedCount int
+}
+
+// NewBlackList creates a new instance of blackList.
+func NewBlackList(maxPeers int, expiryTime time.Duration, blacklistedCount int) *blackList {
+	bl := &blackList{
+		peers:            make(map[string]*BlackListPeer),
+		peerHeap:         make(PeerHeap, 0, maxPeers),
+		maxPeers:         maxPeers,
+		expiryTime:       expiryTime,
+		blacklistedCount: blacklistedCount,
+	}
+	heap.Init(&bl.peerHeap)
+	return bl
+}
+
+// AddOrUpdatePeer adds or updates a peer in the map, rejecting invalid IDs.
+func (bl *blackList) AddOrUpdatePeer(id string, headBlock int64) {
+	if id == "" {
+		return // Reject empty ID
+	}
+
+	bl.mu.Lock()
+	defer bl.mu.Unlock()
+
+	peer, exists := bl.peers[id]
+	if exists {
+		if peer.HeadBlock != headBlock {
+			peer.HeadBlock = headBlock
+			peer.LastSeen = time.Now()
+			peer.BlacklistCount = 0
+			heap.Fix(&bl.peerHeap, peer.index)
+		}
+	} else {
+		if len(bl.peers) >= bl.maxPeers {
+			oldest := heap.Pop(&bl.peerHeap).(*BlackListPeer)
+			delete(bl.peers, oldest.ID) // Corrected to use ID
+		}
+		newPeer := &BlackListPeer{
+			ID: id, HeadBlock: headBlock, LastSeen: time.Now(), BlacklistCount: 0,
+		}
+		bl.peers[id] = newPeer
+		heap.Push(&bl.peerHeap, newPeer)
+	}
+}
+
+// BlacklistStalePeers updates the blacklist count of stale peers.
+func (bl *blackList) BlacklistStalePeers() {
+	bl.mu.Lock()
+	defer bl.mu.Unlock()
+
+	now := time.Now()
+	for _, peer := range bl.peers {
+		if now.Sub(peer.LastSeen) > bl.expiryTime {
+			peer.BlacklistCount++
+		}
+	}
+}
+
+// IsBlacklisted checks if a peer is blacklisted.
+func (bl *blackList) IsBlacklisted(id string) bool {
+	bl.mu.Lock()
+	defer bl.mu.Unlock()
+
+	peer, exists := bl.peers[id]
+	return exists && peer.BlacklistCount >= bl.blacklistedCount
+}

eth/blacklist_test.go

@@ -0,0 +1,161 @@
+package eth
+
+import (
+	"sync"
+	"testing"
+	"time"
+)
+
+// TestAddOrUpdatePeer tests adding new peers and updating existing ones.
+func TestAddOrUpdatePeer(t *testing.T) {
+	bl := NewBlackList(2, 10*time.Minute, 3)
+	bl.AddOrUpdatePeer("peer1", 100)
+	if len(bl.peers) != 1 {
+		t.Errorf("Expected 1 peer, got %d", len(bl.peers))
+	}
+
+	// Test updating the same peer
+	bl.AddOrUpdatePeer("peer1", 101)
+	if bl.peers["peer1"].HeadBlock != 101 {
+		t.Errorf("Expected head block 101, got %d", bl.peers["peer1"].HeadBlock)
+	}
+
+	// Test adding another peer and triggering the maxPeers limit
+	bl.AddOrUpdatePeer("peer2", 102)
+	bl.AddOrUpdatePeer("peer3", 103) // This should remove the oldest (peer1)
+	if len(bl.peers) != 2 {
+		t.Errorf("Expected 2 peers, got %d", len(bl.peers))
+	}
+	if _, exists := bl.peers["peer1"]; exists {
+		t.Errorf("Expected peer1 to be removed")
+	}
+}
+
+// TestBlacklistStalePeers tests the automatic blacklisting of stale peers.
+func TestBlacklistStalePeers(t *testing.T) {
+	bl := NewBlackList(2, 1*time.Minute, 1)
+	bl.AddOrUpdatePeer("peer1", 100)
+	time.Sleep(2 * time.Minute) // simulate time passing
+	bl.BlacklistStalePeers()
+
+	if bl.peers["peer1"].BlacklistCount != 1 {
+		t.Errorf("Expected BlacklistCount of 1, got %d", bl.peers["peer1"].BlacklistCount)
+	}
+}
+
+// TestIsBlacklisted tests checking if a peer is blacklisted.
+func TestIsBlacklisted(t *testing.T) {
+	bl := NewBlackList(2, 1*time.Minute, 1)
+	bl.AddOrUpdatePeer("peer1", 100)
+	bl.peers["peer1"].LastSeen = time.Now().Add(-2 * time.Minute) // make peer stale
+	bl.BlacklistStalePeers()
+
+	if !bl.IsBlacklisted("peer1") {
+		t.Errorf("Expected peer1 to be blacklisted")
+	}
+}
+
+// TestEdgeCases tests handling of edge cases such as invalid IDs.
+func TestEdgeCases(t *testing.T) {
+	bl := NewBlackList(2, 1*time.Minute, 1)
+	bl.AddOrUpdatePeer("", 100) // testing with empty ID
+	if len(bl.peers) != 0 {
+		t.Errorf("Expected 0 peers, got %d", len(bl.peers))
+	}
+}
+
+// TestAddOrUpdatePeer_MaxPeers tests behavior when adding peers up to and beyond the maximum limit.
+func TestAddOrUpdatePeer_MaxPeers(t *testing.T) {
+	bl := NewBlackList(3, 10*time.Minute, 3)
+
+	bl.AddOrUpdatePeer("peer1", 100)
+	bl.AddOrUpdatePeer("peer2", 101)
+	bl.AddOrUpdatePeer("peer3", 102)
+	bl.AddOrUpdatePeer("peer4", 103) // This should remove peer1
+
+	if len(bl.peers) != 3 {
+		t.Errorf("Expected 3 peers, got %d", len(bl.peers))
+	}
+
+	if _, exists := bl.peers["peer1"]; exists {
+		t.Errorf("Expected peer1 to be removed")
+	}
+}
+
+// TestBlacklistCountOverflow checks how the system handles when a peer's BlacklistCount exceeds the threshold.
+func TestBlacklistCountOverflow(t *testing.T) {
+	bl := NewBlackList(2, 1*time.Second, 2)
+	bl.AddOrUpdatePeer("peer1", 100)
+
+	// Simulate multiple blacklist increments
+	time.Sleep(2 * time.Second)
+	bl.BlacklistStalePeers()
+	bl.BlacklistStalePeers()
+
+	if !bl.IsBlacklisted("peer1") {
+		t.Errorf("Expected peer1 to be blacklisted after exceeding blacklist count")
+	}
+}
+
+// TestExpiryTimeBoundary tests behavior when a peer's LastSeen is exactly at the expiry boundary.
+func TestExpiryTimeBoundary(t *testing.T) {
+	bl := NewBlackList(2, 1*time.Second, 2)
+	bl.AddOrUpdatePeer("peer1", 100)
+	time.Sleep(1 * time.Second)
+
+	bl.BlacklistStalePeers() // Should increment blacklist count but not blacklisted yet
+
+	if bl.peers["peer1"].BlacklistCount != 1 {
+		t.Errorf("Expected BlacklistCount of 1, got %d", bl.peers["peer1"].BlacklistCount)
+	}
+
+	if bl.IsBlacklisted("peer1") {
+		t.Errorf("Peer1 should not be blacklisted yet")
+	}
+}
+
+// TestConcurrentAccess tests concurrent access to the blackList.
+func TestConcurrentAccess(t *testing.T) {
+	bl := NewBlackList(100, 10*time.Minute, 3)
+	var wg sync.WaitGroup
+
+	for i := 0; i < 50; i++ {
+		wg.Add(1)
+		go func(id string) {
+			defer wg.Done()
+			bl.AddOrUpdatePeer(id, int64(i))
+		}(string(rune('a' + i)))
+	}
+
+	wg.Wait()
+
+	if len(bl.peers) != 50 {
+		t.Errorf("Expected 50 peers, got %d", len(bl.peers))
+	}
+}
+
+// TestReaddingBlacklistedPeer tests the behavior when a blacklisted peer is re-added.
+func TestReaddingBlacklistedPeer(t *testing.T) {
+	bl := NewBlackList(2, 1*time.Second, 1)
+	bl.AddOrUpdatePeer("peer1", 100)
+
+	// Simulate time passing to trigger blacklist
+	time.Sleep(2 * time.Second)
+	bl.BlacklistStalePeers()
+
+	// Ensure peer1 is blacklisted
+	if !bl.IsBlacklisted("peer1") {
+		t.Errorf("Expected peer1 to be blacklisted")
+	}
+
+	// Re-add the same peer
+	bl.AddOrUpdatePeer("peer1", 101)
+
+	if bl.peers["peer1"].BlacklistCount != 0 {
+		t.Errorf("Expected BlacklistCount to be reset, got %d", bl.peers["peer1"].BlacklistCount)
+	}
+
+	if bl.IsBlacklisted("peer1") {
+		t.Errorf("Peer1 should not be blacklisted after re-adding with updated information")
+	}
+}

eth/handler.go

@@ -172,6 +172,8 @@ type handler struct {
 
 	handlerStartCh chan struct{}
 	handlerDoneCh  chan struct{}
+
+	blackList *blackList
 }
 
 // newHandler returns a handler for all Ethereum chain management protocol.
@@ -702,6 +704,7 @@ func (h *handler) unregisterPeer(id string) {
 func (h *handler) Start(maxPeers int, maxPeersPerIP int) {
 	h.maxPeers = maxPeers
 	h.maxPeersPerIP = maxPeersPerIP
+	h.blackList = NewBlackList(maxPeers, 1*time.Hour, 3)
 	// broadcast and announce transactions (only new ones, not resurrected ones)
 	h.wg.Add(1)
 	h.txsCh = make(chan core.NewTxsEvent, txChanSize)