les: reject client if it makes too many invalid requests (#19691)

* les: reject client connection if it makes too much invalid req

* les: address comments

* les: use uint32

* les: fix variable name

* les: add invalid counter for duplicate invalid req

3 files changed, 40 insertions, 14 deletions

diff --git a/les/handler.go b/les/handler.go
index 4e98e0b32..c7bd23103 100644
--- a/les/handler.go
+++ b/les/handler.go
@@ -19,9 +19,11 @@ package les
 import (
 	"encoding/binary"
 	"encoding/json"
+	"errors"
 	"fmt"
 	"math/big"
 	"sync"
+	"sync/atomic"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -44,6 +46,8 @@ import (
 	"github.com/ethereum/go-ethereum/trie"
 )
 
+var errTooManyInvalidRequest = errors.New("too many invalid requests made")
+
 const (
 	softResponseLimit = 2 * 1024 * 1024 // Target maximum size of returned blocks, headers or node data.
 	estHeaderRlpSize  = 500             // Approximate size of an RLP encoded block header
@@ -524,6 +528,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 						origin = pm.blockchain.GetHeaderByNumber(query.Origin.Number)
 					}
 					if origin == nil {
+						atomic.AddUint32(&p.invalidCount, 1)
 						break
 					}
 					headers = append(headers, origin)
@@ -570,7 +575,6 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 						} else {
 							unknown = true
 						}
-
 					case !query.Reverse:
 						// Number based traversal towards the leaf block
 						query.Origin.Number += query.Skip + 1
@@ -628,15 +632,18 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 						sendResponse(req.ReqID, 0, nil, task.servingTime)
 						return
 					}
+					// Retrieve the requested block body, stopping if enough was found
 					if bytes >= softResponseLimit {
 						break
 					}
-					// Retrieve the requested block body, stopping if enough was found
-					if number := rawdb.ReadHeaderNumber(pm.chainDb, hash); number != nil {
-						if data := rawdb.ReadBodyRLP(pm.chainDb, hash, *number); len(data) != 0 {
-							bodies = append(bodies, data)
-							bytes += len(data)
-						}
+					number := rawdb.ReadHeaderNumber(pm.chainDb, hash)
+					if number == nil {
+						atomic.AddUint32(&p.invalidCount, 1)
+						continue
+					}
+					if data := rawdb.ReadBodyRLP(pm.chainDb, hash, *number); len(data) != 0 {
+						bodies = append(bodies, data)
+						bytes += len(data)
 					}
 				}
 				sendResponse(req.ReqID, uint64(reqCnt), p.ReplyBlockBodiesRLP(req.ReqID, bodies), task.done())
@@ -691,6 +698,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 					number := rawdb.ReadHeaderNumber(pm.chainDb, request.BHash)
 					if number == nil {
 						p.Log().Warn("Failed to retrieve block num for code", "hash", request.BHash)
+						atomic.AddUint32(&p.invalidCount, 1)
 						continue
 					}
 					header := rawdb.ReadHeader(pm.chainDb, request.BHash, *number)
@@ -703,6 +711,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 					local := pm.blockchain.CurrentHeader().Number.Uint64()
 					if !pm.server.archiveMode && header.Number.Uint64()+core.TriesInMemory <= local {
 						p.Log().Debug("Reject stale code request", "number", header.Number.Uint64(), "head", local)
+						atomic.AddUint32(&p.invalidCount, 1)
 						continue
 					}
 					triedb := pm.blockchain.StateCache().TrieDB()
@@ -710,6 +719,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 					account, err := pm.getAccount(triedb, header.Root, common.BytesToHash(request.AccKey))
 					if err != nil {
 						p.Log().Warn("Failed to retrieve account for code", "block", header.Number, "hash", header.Hash(), "account", common.BytesToHash(request.AccKey), "err", err)
+						atomic.AddUint32(&p.invalidCount, 1)
 						continue
 					}
 					code, err := triedb.Node(common.BytesToHash(account.CodeHash))
@@ -776,9 +786,12 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 					}
 					// Retrieve the requested block's receipts, skipping if unknown to us
 					var results types.Receipts
-					if number := rawdb.ReadHeaderNumber(pm.chainDb, hash); number != nil {
-						results = rawdb.ReadRawReceipts(pm.chainDb, hash, *number)
+					number := rawdb.ReadHeaderNumber(pm.chainDb, hash)
+					if number == nil {
+						atomic.AddUint32(&p.invalidCount, 1)
+						continue
 					}
+					results = rawdb.ReadRawReceipts(pm.chainDb, hash, *number)
 					if results == nil {
 						if header := pm.blockchain.GetHeaderByHash(hash); header == nil || header.ReceiptHash != types.EmptyRootHash {
 							continue
@@ -853,6 +866,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 
 						if number = rawdb.ReadHeaderNumber(pm.chainDb, request.BHash); number == nil {
 							p.Log().Warn("Failed to retrieve block num for proof", "hash", request.BHash)
+							atomic.AddUint32(&p.invalidCount, 1)
 							continue
 						}
 						if header = rawdb.ReadHeader(pm.chainDb, request.BHash, *number); header == nil {
@@ -864,12 +878,14 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 						local := pm.blockchain.CurrentHeader().Number.Uint64()
 						if !pm.server.archiveMode && header.Number.Uint64()+core.TriesInMemory <= local {
 							p.Log().Debug("Reject stale trie request", "number", header.Number.Uint64(), "head", local)
+							atomic.AddUint32(&p.invalidCount, 1)
 							continue
 						}
 						root = header.Root
 					}
 					// If a header lookup failed (non existent), ignore subsequent requests for the same header
 					if root == (common.Hash{}) {
+						atomic.AddUint32(&p.invalidCount, 1)
 						continue
 					}
 					// Open the account or storage trie for the request
@@ -888,6 +904,7 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 						account, err := pm.getAccount(statedb.TrieDB(), root, common.BytesToHash(request.AccKey))
 						if err != nil {
 							p.Log().Warn("Failed to retrieve account for proof", "block", header.Number, "hash", header.Hash(), "account", common.BytesToHash(request.AccKey), "err", err)
+							atomic.AddUint32(&p.invalidCount, 1)
 							continue
 						}
 						trie, err = statedb.OpenStorageTrie(common.BytesToHash(request.AccKey), account.Root)
@@ -1134,6 +1151,11 @@ func (pm *ProtocolManager) handleMsg(p *peer) error {
 			}
 		}
 	}
+	// If the client has made too much invalid request(e.g. request a non-exist data),
+	// reject them to prevent SPAM attack.
+	if atomic.LoadUint32(&p.invalidCount) > maxRequestErrors {
+		return errTooManyInvalidRequest
+	}
 	return nil
 }
 
diff --git a/les/handler_test.go b/les/handler_test.go
index 51f0a1a0e..c3608ebdd 100644
--- a/les/handler_test.go
+++ b/les/handler_test.go
@@ -597,9 +597,10 @@ func TestStopResumeLes3(t *testing.T) {
 	expBuf := testBufLimit
 	var reqID uint64
 
+	header := pm.blockchain.CurrentHeader()
 	req := func() {
 		reqID++
-		sendRequest(peer.app, GetBlockHeadersMsg, reqID, testCost, &getBlockHeadersData{Origin: hashOrNumber{Hash: common.Hash{1}}, Amount: 1})
+		sendRequest(peer.app, GetBlockHeadersMsg, reqID, testCost, &getBlockHeadersData{Origin: hashOrNumber{Hash: header.Hash()}, Amount: 1})
 	}
 
 	for i := 1; i <= 5; i++ {
@@ -607,8 +608,8 @@ func TestStopResumeLes3(t *testing.T) {
 		for expBuf >= testCost {
 			req()
 			expBuf -= testCost
-			if err := expectResponse(peer.app, BlockHeadersMsg, reqID, expBuf, nil); err != nil {
-				t.Errorf("expected response and failed: %v", err)
+			if err := expectResponse(peer.app, BlockHeadersMsg, reqID, expBuf, []*types.Header{header}); err != nil {
+				t.Fatalf("expected response and failed: %v", err)
 			}
 		}
 		// send some more requests in excess and expect a single StopMsg
diff --git a/les/peer.go b/les/peer.go
index 56d316f50..a615c9b73 100644
--- a/les/peer.go
+++ b/les/peer.go
@@ -42,7 +42,10 @@ var (
 	errNotRegistered     = errors.New("peer is not registered")
 )
 
-const maxResponseErrors = 50 // number of invalid responses tolerated (makes the protocol less brittle but still avoids spam)
+const (
+	maxRequestErrors  = 20 // number of invalid requests tolerated (makes the protocol less brittle but still avoids spam)
+	maxResponseErrors = 50 // number of invalid responses tolerated (makes the protocol less brittle but still avoids spam)
+)
 
 // capacity limitation for parameter updates
 const (
@@ -69,7 +72,6 @@ const (
 
 type peer struct {
 	*p2p.Peer
-
 	rw p2p.MsgReadWriter
 
 	version int    // Protocol version negotiated
@@ -89,6 +91,7 @@ type peer struct {
 	// RequestProcessed is called
 	responseLock  sync.Mutex
 	responseCount uint64
+	invalidCount  uint32
 
 	poolEntry      *poolEntry
 	hasBlock       func(common.Hash, uint64, bool) bool