eth/protocols/eth: store block range on peer

eth/peer.go

@@ -17,6 +17,7 @@
 package eth
 
 import (
+	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/eth/protocols/eth"
 	"github.com/ethereum/go-ethereum/eth/protocols/snap"
 )
@@ -25,6 +26,13 @@ import (
 // about a connected peer.
 type ethPeerInfo struct {
 	Version    uint            `json:"version"` // Ethereum protocol version negotiated
+	BlockRange *peerBlockRange `json:"blockRange"`
+}
+
+type peerBlockRange struct {
+	Earliest   uint64      `json:"earliestBlock"`
+	Latest     uint64      `json:"latestBlock"`
+	LatestHash common.Hash `json:"latestBlockHash"`
 }
 
 // ethPeer is a wrapper around eth.Peer to maintain a few extra metadata.
@@ -35,9 +43,15 @@ type ethPeer struct {
 
 // info gathers and returns some `eth` protocol metadata known about a peer.
 func (p *ethPeer) info() *ethPeerInfo {
-	return &ethPeerInfo{
-		Version: p.Version(),
+	info := &ethPeerInfo{Version: p.Version()}
+	if br := p.BlockRange(); br != nil {
+		info.BlockRange = &peerBlockRange{
+			Earliest:   br.EarliestBlock,
+			Latest:     br.LatestBlock,
+			LatestHash: br.LatestBlockHash,
 		}
+	}
+	return info
 }
 
 // snapPeerInfo represents a short summary of the `snap` sub-protocol metadata known

eth/protocols/eth/handlers.go

@@ -548,6 +548,7 @@ func handleBlockRangeUpdate(backend Backend, msg Decoder, peer *Peer) error {
 	if err := msg.Decode(&update); err != nil {
 		return err
 	}
-	// We don't do anything with these messages for now.
+	// We don't do anything with these messages for now, just store them on the peer.
+	peer.lastRange.Store(&update)
 	return nil
 }

eth/protocols/eth/handshake.go

@@ -137,6 +137,12 @@ func (p *Peer) readStatus69(networkID uint64, status *StatusPacket69, genesis co
 	if err := forkFilter(status.ForkID); err != nil {
 		return fmt.Errorf("%w: %v", errForkIDRejected, err)
 	}
+	// Handle initial block range.
+	p.lastRange.Store(&BlockRangeUpdatePacket{
+		EarliestBlock:   status.EarliestBlock,
+		LatestBlock:     status.LatestBlock,
+		LatestBlockHash: status.LatestBlockHash,
+	})
 	return nil
 }
 

eth/protocols/eth/peer.go

@@ -18,6 +18,7 @@ package eth
 
 import (
 	"math/rand"
+	"sync/atomic"
 
 	mapset "github.com/deckarep/golang-set/v2"
 	"github.com/ethereum/go-ethereum/common"
@@ -47,6 +48,7 @@ type Peer struct {
 	*p2p.Peer                   // The embedded P2P package peer
 	rw        p2p.MsgReadWriter // Input/output streams for snap
 	version   uint              // Protocol version negotiated
+	lastRange atomic.Pointer[BlockRangeUpdatePacket]
 
 	txpool      TxPool             // Transaction pool used by the broadcasters for liveness checks
 	knownTxs    *knownCache        // Set of transaction hashes known to be known by this peer
@@ -102,6 +104,12 @@ func (p *Peer) Version() uint {
 	return p.version
 }
 
+// BlockRange returns the latest announced block range.
+// This will be nil for peers below protocol version eth/69.
+func (p *Peer) BlockRange() *BlockRangeUpdatePacket {
+	return p.lastRange.Load()
+}
+
 // KnownTransaction returns whether peer is known to already have a transaction.
 func (p *Peer) KnownTransaction(hash common.Hash) bool {
 	return p.knownTxs.Contains(hash)