eth, les: add error when accessing missing block state (#18346)

This change makes getBalance, getCode, getStorageAt, getProof,
call, getTransactionCount return an error if the block number in
the request doesn't exist. getHeaderByNumber still returns null
for missing headers.

eth/api_backend.go

@@ -18,6 +18,7 @@ package eth
 
 import (
 	"context"
+	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/accounts"
@@ -95,9 +96,12 @@ func (b *EthAPIBackend) StateAndHeaderByNumber(ctx context.Context, blockNr rpc.
 	}
 	// Otherwise resolve the block number and return its state
 	header, err := b.HeaderByNumber(ctx, blockNr)
-	if header == nil || err != nil {
+	if err != nil {
 		return nil, nil, err
 	}
+	if header == nil {
+		return nil, nil, errors.New("header not found")
+	}
 	stateDb, err := b.eth.BlockChain().StateAt(header.Root)
 	return stateDb, header, err
 }

ethclient/ethclient_test.go

@@ -17,13 +17,24 @@
 package ethclient
 
 import (
+	"context"
+	"errors"
 	"fmt"
 	"math/big"
 	"reflect"
 	"testing"
+	"time"
 
 	"github.com/ethereum/go-ethereum"
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/consensus/ethash"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/eth"
+	"github.com/ethereum/go-ethereum/node"
+	"github.com/ethereum/go-ethereum/params"
 )
 
 // Verify that Client implements the ethereum interfaces.
@@ -150,3 +161,143 @@ func TestToFilterArg(t *testing.T) {
 		})
 	}
 }
+
+var (
+	testKey, _  = crypto.HexToECDSA("b71c71a67e1177ad4e901695e1b4b9ee17ae16c6668d313eac2f96dbcda3f291")
+	testAddr    = crypto.PubkeyToAddress(testKey.PublicKey)
+	testBalance = big.NewInt(2e10)
+)
+
+func newTestBackend(t *testing.T) (*node.Node, []*types.Block) {
+	// Generate test chain.
+	genesis, blocks := generateTestChain()
+
+	// Start Ethereum service.
+	var ethservice *eth.Ethereum
+	n, err := node.New(&node.Config{})
+	n.Register(func(ctx *node.ServiceContext) (node.Service, error) {
+		config := &eth.Config{Genesis: genesis}
+		config.Ethash.PowMode = ethash.ModeFake
+		ethservice, err = eth.New(ctx, config)
+		return ethservice, err
+	})
+
+	// Import the test chain.
+	if err := n.Start(); err != nil {
+		t.Fatalf("can't start test node: %v", err)
+	}
+	if _, err := ethservice.BlockChain().InsertChain(blocks[1:]); err != nil {
+		t.Fatalf("can't import test blocks: %v", err)
+	}
+	return n, blocks
+}
+
+func generateTestChain() (*core.Genesis, []*types.Block) {
+	db := rawdb.NewMemoryDatabase()
+	config := params.AllEthashProtocolChanges
+	genesis := &core.Genesis{
+		Config:    config,
+		Alloc:     core.GenesisAlloc{testAddr: {Balance: testBalance}},
+		ExtraData: []byte("test genesis"),
+		Timestamp: 9000,
+	}
+	generate := func(i int, g *core.BlockGen) {
+		g.OffsetTime(5)
+		g.SetExtra([]byte("test"))
+	}
+	gblock := genesis.ToBlock(db)
+	engine := ethash.NewFaker()
+	blocks, _ := core.GenerateChain(config, gblock, engine, db, 1, generate)
+	blocks = append([]*types.Block{gblock}, blocks...)
+	return genesis, blocks
+}
+
+func TestHeader(t *testing.T) {
+	backend, chain := newTestBackend(t)
+	client, _ := backend.Attach()
+	defer backend.Stop()
+	defer client.Close()
+
+	tests := map[string]struct {
+		block   *big.Int
+		want    *types.Header
+		wantErr error
+	}{
+		"genesis": {
+			block: big.NewInt(0),
+			want:  chain[0].Header(),
+		},
+		"first_block": {
+			block: big.NewInt(1),
+			want:  chain[1].Header(),
+		},
+		"future_block": {
+			block: big.NewInt(1000000000),
+			want:  nil,
+		},
+	}
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			ec := NewClient(client)
+			ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+			defer cancel()
+
+			got, err := ec.HeaderByNumber(ctx, tt.block)
+			if tt.wantErr != nil && (err == nil || err.Error() != tt.wantErr.Error()) {
+				t.Fatalf("HeaderByNumber(%v) error = %q, want %q", tt.block, err, tt.wantErr)
+			}
+			if got != nil && got.Number.Sign() == 0 {
+				got.Number = big.NewInt(0) // hack to make DeepEqual work
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Fatalf("HeaderByNumber(%v)\n   = %v\nwant %v", tt.block, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestBalanceAt(t *testing.T) {
+	backend, _ := newTestBackend(t)
+	client, _ := backend.Attach()
+	defer backend.Stop()
+	defer client.Close()
+
+	tests := map[string]struct {
+		account common.Address
+		block   *big.Int
+		want    *big.Int
+		wantErr error
+	}{
+		"valid_account": {
+			account: testAddr,
+			block:   big.NewInt(1),
+			want:    testBalance,
+		},
+		"non_existent_account": {
+			account: common.Address{1},
+			block:   big.NewInt(1),
+			want:    big.NewInt(0),
+		},
+		"future_block": {
+			account: testAddr,
+			block:   big.NewInt(1000000000),
+			want:    big.NewInt(0),
+			wantErr: errors.New("header not found"),
+		},
+	}
+	for name, tt := range tests {
+		t.Run(name, func(t *testing.T) {
+			ec := NewClient(client)
+			ctx, cancel := context.WithTimeout(context.Background(), 100*time.Millisecond)
+			defer cancel()
+
+			got, err := ec.BalanceAt(ctx, tt.account, tt.block)
+			if tt.wantErr != nil && (err == nil || err.Error() != tt.wantErr.Error()) {
+				t.Fatalf("BalanceAt(%x, %v) error = %q, want %q", tt.account, tt.block, err, tt.wantErr)
+			}
+			if got.Cmp(tt.want) != 0 {
+				t.Fatalf("BalanceAt(%x, %v) = %v, want %v", tt.account, tt.block, got, tt.want)
+			}
+		})
+	}
+}

les/api_backend.go

@@ -18,6 +18,7 @@ package les
 
 import (
 	"context"
+	"errors"
 	"math/big"
 
 	"github.com/ethereum/go-ethereum/accounts"
@@ -78,9 +79,12 @@ func (b *LesApiBackend) BlockByNumber(ctx context.Context, blockNr rpc.BlockNumb
 
 func (b *LesApiBackend) StateAndHeaderByNumber(ctx context.Context, blockNr rpc.BlockNumber) (*state.StateDB, *types.Header, error) {
 	header, err := b.HeaderByNumber(ctx, blockNr)
-	if header == nil || err != nil {
+	if err != nil {
 		return nil, nil, err
 	}
+	if header == nil {
+		return nil, nil, errors.New("header not found")
+	}
 	return light.NewState(ctx, header, b.eth.odr), header, nil
 }