eth/fetcher: throttle tx fetches to 128KB responses

eth/fetcher/tx_fetcher.go

@@ -39,16 +39,22 @@ const (
 	// can announce in a short time.
 	maxTxAnnounces = 4096
 
-	// maxTxRetrievals is the maximum transaction number can be fetched in one
-	// request. The rationale to pick 256 is:
-	//   - In eth protocol, the softResponseLimit is 2MB. Nowadays according to
-	//     Etherscan the average transaction size is around 200B, so in theory
-	//     we can include lots of transaction in a single protocol packet.
-	//   - However the maximum size of a single transaction is raised to 128KB,
-	//     so pick a middle value here to ensure we can maximize the efficiency
-	//     of the retrieval and response size overflow won't happen in most cases.
+	// maxTxRetrievals is the maximum number of transactions that can be fetched
+	// in one request. The rationale for picking 256 is to have a reasonabe lower
+	// bound for the transferred data (don't waste RTTs, transfer more meaningful
+	// batch sizes), but also have an upper bound on the sequentiality to allow
+	// using our entire peerset for deliveries.
+	//
+	// This number also acts as a failsafe against malicious announces which might
+	// cause us to request more data than we'd expect.
 	maxTxRetrievals = 256
 
+	// maxTxRetrievalSize is the max number of bytes that delivered transactions
+	// should weigh according to the announcements. The 128KB was chosen to limit
+	// retrieving a maximum of one blob transaction at a time to minimize hogging
+	// a connection between two peers.
+	maxTxRetrievalSize = 128 * 1024
+
 	// maxTxUnderpricedSetSize is the size of the underpriced transaction set that
 	// is used to track recent transactions that have been dropped so we don't
 	// re-request them.
@@ -859,25 +865,36 @@ func (f *TxFetcher) scheduleFetches(timer *mclock.Timer, timeout chan struct{},
 		if len(f.announces[peer]) == 0 {
 			return // continue in the for-each
 		}
-		hashes := make([]common.Hash, 0, maxTxRetrievals)
-		f.forEachHash(f.announces[peer], func(hash common.Hash) bool {
-			if _, ok := f.fetching[hash]; !ok {
-				// Mark the hash as fetching and stash away possible alternates
-				f.fetching[hash] = peer
-
-				if _, ok := f.alternates[hash]; ok {
-					panic(fmt.Sprintf("alternate tracker already contains fetching item: %v", f.alternates[hash]))
-				}
-				f.alternates[hash] = f.announced[hash]
-				delete(f.announced, hash)
+		var (
+			hashes = make([]common.Hash, 0, maxTxRetrievals)
+			bytes  uint64
+		)
+		f.forEachAnnounce(f.announces[peer], func(hash common.Hash, meta *txMetadata) bool {
+			// If the transaction is alcear fetching, skip to the next one
+			if _, ok := f.fetching[hash]; ok {
+				return true
+			}
+			// Mark the hash as fetching and stash away possible alternates
+			f.fetching[hash] = peer
 
-				// Accumulate the hash and stop if the limit was reached
-				hashes = append(hashes, hash)
-				if len(hashes) >= maxTxRetrievals {
-					return false // break in the for-each
+			if _, ok := f.alternates[hash]; ok {
+				panic(fmt.Sprintf("alternate tracker already contains fetching item: %v", f.alternates[hash]))
+			}
+			f.alternates[hash] = f.announced[hash]
+			delete(f.announced, hash)
+
+			// Accumulate the hash and stop if the limit was reached
+			hashes = append(hashes, hash)
+			if len(hashes) >= maxTxRetrievals {
+				return false // break in the for-each
+			}
+			if meta != nil { // Only set eth/68 and upwards
+				bytes += uint64(meta.size)
+				if bytes >= maxTxRetrievalSize {
+					return false
 				}
 			}
-			return true // continue in the for-each
+			return true // scheduled, try to add more
 		})
 		// If any hashes were allocated, request them from the peer
 		if len(hashes) > 0 {
@@ -922,27 +939,28 @@ func (f *TxFetcher) forEachPeer(peers map[string]struct{}, do func(peer string))
 	}
 }
 
-// forEachHash does a range loop over a map of hashes in production, but during
-// testing it does a deterministic sorted random to allow reproducing issues.
-func (f *TxFetcher) forEachHash(hashes map[common.Hash]*txMetadata, do func(hash common.Hash) bool) {
+// forEachAnnounce does a range loop over a map of announcements in production,
+// but during testing it does a deterministic sorted random to allow reproducing
+// issues.
+func (f *TxFetcher) forEachAnnounce(announces map[common.Hash]*txMetadata, do func(hash common.Hash, meta *txMetadata) bool) {
 	// If we're running production, use whatever Go's map gives us
 	if f.rand == nil {
-		for hash := range hashes {
-			if !do(hash) {
+		for hash, meta := range announces {
+			if !do(hash, meta) {
 				return
 			}
 		}
 		return
 	}
 	// We're running the test suite, make iteration deterministic
-	list := make([]common.Hash, 0, len(hashes))
-	for hash := range hashes {
+	list := make([]common.Hash, 0, len(announces))
+	for hash := range announces {
 		list = append(list, hash)
 	}
 	sortHashes(list)
 	rotateHashes(list, f.rand.Intn(len(list)))
 	for _, hash := range list {
-		if !do(hash) {
+		if !do(hash, announces[hash]) {
 			return
 		}
 	}

eth/fetcher/tx_fetcher_test.go

@@ -27,6 +27,7 @@ import (
 	"github.com/ethereum/go-ethereum/common/mclock"
 	"github.com/ethereum/go-ethereum/core/txpool"
 	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/params"
 )
 
 var (
@@ -993,15 +994,14 @@ func TestTransactionFetcherTimeoutTimerResets(t *testing.T) {
 	})
 }
 
-// Tests that if thousands of transactions are announces, only a small
+// Tests that if thousands of transactions are announced, only a small
 // number of them will be requested at a time.
 func TestTransactionFetcherRateLimiting(t *testing.T) {
-	// Create a slew of transactions and to announce them
+	// Create a slew of transactions and announce them
 	var hashes []common.Hash
 	for i := 0; i < maxTxAnnounces; i++ {
 		hashes = append(hashes, common.Hash{byte(i / 256), byte(i % 256)})
 	}
-
 	testTransactionFetcherParallel(t, txFetcherTest{
 		init: func() *TxFetcher {
 			return NewTxFetcher(
@@ -1029,6 +1029,68 @@ func TestTransactionFetcherRateLimiting(t *testing.T) {
 	})
 }
 
+// Tests that if huge transactions are announced, only a small number of them will
+// be requested at a time, to keep the responses below a resonable level.
+func TestTransactionFetcherBandwidthLimiting(t *testing.T) {
+	testTransactionFetcherParallel(t, txFetcherTest{
+		init: func() *TxFetcher {
+			return NewTxFetcher(
+				func(common.Hash) bool { return false },
+				nil,
+				func(string, []common.Hash) error { return nil },
+				nil,
+			)
+		},
+		steps: []interface{}{
+			// Announce mid size transactions from A to verify that multiple
+			// ones can be piled into a single request.
+			doTxNotify{peer: "A",
+				hashes: []common.Hash{{0x01}, {0x02}, {0x03}, {0x04}},
+				types:  []byte{types.LegacyTxType, types.LegacyTxType, types.LegacyTxType, types.LegacyTxType},
+				sizes:  []uint32{48 * 1024, 48 * 1024, 48 * 1024, 48 * 1024},
+			},
+			// Announce exactly on the limit transactions to see that only one
+			// gets requested
+			doTxNotify{peer: "B",
+				hashes: []common.Hash{{0x05}, {0x06}},
+				types:  []byte{types.LegacyTxType, types.LegacyTxType},
+				sizes:  []uint32{maxTxRetrievalSize, maxTxRetrievalSize},
+			},
+			// Announce oversized blob transactions to see that overflows are ok
+			doTxNotify{peer: "C",
+				hashes: []common.Hash{{0x07}, {0x08}},
+				types:  []byte{types.BlobTxType, types.BlobTxType},
+				sizes:  []uint32{params.MaxBlobGasPerBlock, params.MaxBlobGasPerBlock},
+			},
+			doWait{time: txArriveTimeout, step: true},
+			isWaiting(nil),
+			isScheduledWithMeta{
+				tracking: map[string][]announce{
+					"A": {
+						{common.Hash{0x01}, typeptr(types.LegacyTxType), sizeptr(48 * 1024)},
+						{common.Hash{0x02}, typeptr(types.LegacyTxType), sizeptr(48 * 1024)},
+						{common.Hash{0x03}, typeptr(types.LegacyTxType), sizeptr(48 * 1024)},
+						{common.Hash{0x04}, typeptr(types.LegacyTxType), sizeptr(48 * 1024)},
+					},
+					"B": {
+						{common.Hash{0x05}, typeptr(types.LegacyTxType), sizeptr(maxTxRetrievalSize)},
+						{common.Hash{0x06}, typeptr(types.LegacyTxType), sizeptr(maxTxRetrievalSize)},
+					},
+					"C": {
+						{common.Hash{0x07}, typeptr(types.BlobTxType), sizeptr(params.MaxBlobGasPerBlock)},
+						{common.Hash{0x08}, typeptr(types.BlobTxType), sizeptr(params.MaxBlobGasPerBlock)},
+					},
+				},
+				fetching: map[string][]common.Hash{
+					"A": {{0x02}, {0x03}, {0x04}},
+					"B": {{0x06}},
+					"C": {{0x08}},
+				},
+			},
+		},
+	})
+}
+
 // Tests that then number of transactions a peer is allowed to announce and/or
 // request at the same time is hard capped.
 func TestTransactionFetcherDoSProtection(t *testing.T) {
@@ -1664,7 +1726,7 @@ func testTransactionFetcher(t *testing.T, tt txFetcherTest) {
 						if (meta == nil && (ann.kind != nil || ann.size != nil)) ||
 							(meta != nil && (ann.kind == nil || ann.size == nil)) ||
 							(meta != nil && (meta.kind != *ann.kind || meta.size != *ann.size)) {
-							t.Errorf("step %d, peer %s, hash %x: waitslot metadata mismatch: want %v, have %v/%v", i, peer, ann.hash, meta, ann.kind, ann.size)
+							t.Errorf("step %d, peer %s, hash %x: waitslot metadata mismatch: want %v, have %v/%v", i, peer, ann.hash, meta, *ann.kind, *ann.size)
 						}
 					}
 				}
@@ -1733,7 +1795,7 @@ func testTransactionFetcher(t *testing.T, tt txFetcherTest) {
 						if (meta == nil && (ann.kind != nil || ann.size != nil)) ||
 							(meta != nil && (ann.kind == nil || ann.size == nil)) ||
 							(meta != nil && (meta.kind != *ann.kind || meta.size != *ann.size)) {
-							t.Errorf("step %d, peer %s, hash %x: announce metadata mismatch: want %v, have %v/%v", i, peer, ann.hash, meta, ann.kind, ann.size)
+							t.Errorf("step %d, peer %s, hash %x: announce metadata mismatch: want %v, have %v/%v", i, peer, ann.hash, meta, *ann.kind, *ann.size)
 						}
 					}
 				}