core: properly deliver headers close to head

ethereum · Jun 24, 2021 · 0bc022b · 0bc022b
1 parent 2f0fe7a
commit 0bc022b
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Showing 5 changed files with 22 additions and 10 deletions.
diff --git a/core/headerchain.go b/core/headerchain.go
@@ -528,6 +528,16 @@ func (hc *HeaderChain) GetHeaderByNumber(number uint64) *types.Header {
 // GetHeadersFrom returns a contiguous segment of headers, in rlp-form, going
 // backwards from the given number.
 func (hc *HeaderChain) GetHeadersFrom(number, count uint64) []rlp.RawValue {
+	// If the request is for future headers, we still return the portion of
+	// headers that we are able to serve
+	if current := hc.CurrentHeader().Number.Uint64(); current < number {
+		if count >= number-current {
+			count -= number - current
+			number = current
+		} else {
+			return nil
+		}
+	}
 	return rawdb.ReadHeadersRLP(hc.chainDb, number, count)
 }
 

diff --git a/eth/handler_eth_test.go b/eth/handler_eth_test.go
@@ -18,7 +18,6 @@ package eth
 
 import (
 	"fmt"
-	"github.com/ethereum/go-ethereum/rlp"
 	"math/big"
 	"math/rand"
 	"sync/atomic"
@@ -38,6 +37,7 @@ import (
 	"github.com/ethereum/go-ethereum/p2p"
 	"github.com/ethereum/go-ethereum/p2p/enode"
 	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rlp"
 	"github.com/ethereum/go-ethereum/trie"
 )
 

diff --git a/eth/protocols/eth/handler.go b/eth/protocols/eth/handler.go
@@ -36,9 +36,6 @@ const (
 	// softResponseLimit is the target maximum size of replies to data retrievals.
 	softResponseLimit = 2 * 1024 * 1024
 
-	// estHeaderSize is the approximate size of an RLP encoded block header.
-	estHeaderSize = 500
-
 	// maxHeadersServe is the maximum number of block headers to serve. This number
 	// is there to limit the number of disk lookups.
 	maxHeadersServe = 1024

diff --git a/eth/protocols/eth/handler_test.go b/eth/protocols/eth/handler_test.go
@@ -179,10 +179,15 @@ func testGetBlockHeaders(t *testing.T, protocol uint) {
 		{
 			&GetBlockHeadersPacket{Origin: HashOrNumber{Number: 0}, Amount: 1},
 			[]common.Hash{backend.chain.GetBlockByNumber(0).Hash()},
-		}, {
+		},
+		{
 			&GetBlockHeadersPacket{Origin: HashOrNumber{Number: backend.chain.CurrentBlock().NumberU64()}, Amount: 1},
 			[]common.Hash{backend.chain.CurrentBlock().Hash()},
 		},
+		{ // If the peer requests a bit into the future, we deliver what we have
+			&GetBlockHeadersPacket{Origin: HashOrNumber{Number: backend.chain.CurrentBlock().NumberU64()}, Amount: 10},
+			[]common.Hash{backend.chain.CurrentBlock().Hash()},
+		},
 		// Ensure protocol limits are honored
 		{
 			&GetBlockHeadersPacket{Origin: HashOrNumber{Number: backend.chain.CurrentBlock().NumberU64() - 1}, Amount: limit + 10, Reverse: true},
@@ -259,7 +264,7 @@ func testGetBlockHeaders(t *testing.T, protocol uint) {
 		if protocol <= ETH65 {
 			p2p.Send(peer.app, GetBlockHeadersMsg, tt.query)
 			if err := p2p.ExpectMsg(peer.app, BlockHeadersMsg, headers); err != nil {
-				t.Errorf("test %d: headers mismatch: %v", i, err)
+				t.Fatalf("test %d: headers mismatch: %v", i, err)
 			}
 		} else {
 			p2p.Send(peer.app, GetBlockHeadersMsg, GetBlockHeadersPacket66{
@@ -270,7 +275,7 @@ func testGetBlockHeaders(t *testing.T, protocol uint) {
 				RequestId:          123,
 				BlockHeadersPacket: headers,
 			}); err != nil {
-				t.Errorf("test %d: headers mismatch: %v", i, err)
+				t.Fatalf("test %d: headers mismatch: %v", i, err)
 			}
 		}
 		// If the test used number origins, repeat with hashes as the too
@@ -281,7 +286,7 @@ func testGetBlockHeaders(t *testing.T, protocol uint) {
 				if protocol <= ETH65 {
 					p2p.Send(peer.app, GetBlockHeadersMsg, tt.query)
 					if err := p2p.ExpectMsg(peer.app, BlockHeadersMsg, headers); err != nil {
-						t.Errorf("test %d by hash:  headers mismatch: %v", i, err)
+						t.Fatalf("test %d by hash:  headers mismatch: %v", i, err)
 					}
 				} else {
 					p2p.Send(peer.app, GetBlockHeadersMsg, GetBlockHeadersPacket66{
@@ -292,7 +297,7 @@ func testGetBlockHeaders(t *testing.T, protocol uint) {
 						RequestId:          456,
 						BlockHeadersPacket: headers,
 					}); err != nil {
-						t.Errorf("test %d by hash: headers mismatch: %v", i, err)
+						t.Fatalf("test %d by hash: headers mismatch: %v", i, err)
 					}
 				}
 			}

diff --git a/eth/protocols/eth/handlers.go b/eth/protocols/eth/handlers.go
@@ -155,7 +155,7 @@ func answerContiguousBlockHeaderQuery(backend Backend, query *GetBlockHeadersPac
 	if query.Origin.Hash == (common.Hash{}) {
 		// Number mode, just return the canon chain segment. The backend
 		// delivers in [N, N-1, N-2..] descending order, so we need to
-		// accomodate for that.
+		// accommodate for that.
 		from := query.Origin.Number
 		if !query.Reverse {
 			from = from + count - 1