rpc: change BlockNumber constant values to match ethclient (#27219)

ethclient accepts certain negative block number values as specifiers for the "pending",
"safe" and "finalized" block. In case of "pending", the value accepted by ethclient (-1)
did not match rpc.PendingBlockNumber (-2).

This wasn't really a problem, but other values accepted by ethclient did match the
definitions in package rpc, and it's weird to have this one special case where they don't.

To fix it, we decided to change the values of the constants rather than changing ethclient.
The constant values are not otherwise significant. This is a breaking API change, but we
believe not a dangerous one.

---------

Co-authored-by: Felix Lange <fjl@twurst.com>

eth/filters/api_test.go

@@ -56,7 +56,7 @@ func TestUnmarshalJSONNewFilterArgs(t *testing.T) {
 
 	// from, to block number
 	var test1 FilterCriteria
-	vector := fmt.Sprintf(`{"fromBlock":"%#x","toBlock":"%#x"}`, fromBlock, toBlock)
+	vector := fmt.Sprintf(`{"fromBlock":"%v","toBlock":"%v"}`, fromBlock, toBlock)
 	if err := json.Unmarshal([]byte(vector), &test1); err != nil {
 		t.Fatal(err)
 	}

eth/filters/filter.go

@@ -296,6 +296,9 @@ func (f *Filter) checkMatches(ctx context.Context, header *types.Header) ([]*typ
 // pendingLogs returns the logs matching the filter criteria within the pending block.
 func (f *Filter) pendingLogs() ([]*types.Log, error) {
 	block, receipts := f.sys.backend.PendingBlockAndReceipts()
+	if block == nil {
+		return nil, errors.New("pending state not available")
+	}
 	if bloomFilter(block.Bloom(), f.addresses, f.topics) {
 		var unfiltered []*types.Log
 		for _, r := range receipts {

eth/filters/filter_test.go

@@ -29,6 +29,7 @@ import (
 	"github.com/ethereum/go-ethereum/core/types"
 	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/ethereum/go-ethereum/params"
+	"github.com/ethereum/go-ethereum/rpc"
 )
 
 func makeReceipt(addr common.Address) *types.Receipt {
@@ -179,7 +180,7 @@ func TestFilters(t *testing.T) {
 	// Set block 998 as Finalized (-3)
 	rawdb.WriteFinalizedBlockHash(db, chain[998].Hash())
 
-	filter := sys.NewRangeFilter(0, -1, []common.Address{addr}, [][]common.Hash{{hash1, hash2, hash3, hash4}})
+	filter := sys.NewRangeFilter(0, int64(rpc.LatestBlockNumber), []common.Address{addr}, [][]common.Hash{{hash1, hash2, hash3, hash4}})
 	logs, _ := filter.Logs(context.Background())
 	if len(logs) != 4 {
 		t.Error("expected 4 log, got", len(logs))
@@ -193,34 +194,36 @@ func TestFilters(t *testing.T) {
 			sys.NewRangeFilter(900, 999, []common.Address{addr}, [][]common.Hash{{hash3}}),
 			[]common.Hash{hash3},
 		}, {
-			sys.NewRangeFilter(990, -1, []common.Address{addr}, [][]common.Hash{{hash3}}),
+			sys.NewRangeFilter(990, int64(rpc.LatestBlockNumber), []common.Address{addr}, [][]common.Hash{{hash3}}),
 			[]common.Hash{hash3},
 		}, {
 			sys.NewRangeFilter(1, 10, nil, [][]common.Hash{{hash1, hash2}}),
 			[]common.Hash{hash1, hash2},
 		}, {
-			sys.NewRangeFilter(0, -1, nil, [][]common.Hash{{common.BytesToHash([]byte("fail"))}}),
+			sys.NewRangeFilter(0, int64(rpc.LatestBlockNumber), nil, [][]common.Hash{{common.BytesToHash([]byte("fail"))}}),
 			nil,
 		}, {
-			sys.NewRangeFilter(0, -1, []common.Address{common.BytesToAddress([]byte("failmenow"))}, nil),
+			sys.NewRangeFilter(0, int64(rpc.LatestBlockNumber), []common.Address{common.BytesToAddress([]byte("failmenow"))}, nil),
 			nil,
 		}, {
-			sys.NewRangeFilter(0, -1, nil, [][]common.Hash{{common.BytesToHash([]byte("fail"))}, {hash1}}),
+			sys.NewRangeFilter(0, int64(rpc.LatestBlockNumber), nil, [][]common.Hash{{common.BytesToHash([]byte("fail"))}, {hash1}}),
 			nil,
 		}, {
-			sys.NewRangeFilter(-1, -1, nil, nil), []common.Hash{hash4},
+			sys.NewRangeFilter(int64(rpc.LatestBlockNumber), int64(rpc.LatestBlockNumber), nil, nil), []common.Hash{hash4},
 		}, {
-			sys.NewRangeFilter(-3, -1, nil, nil), []common.Hash{hash3, hash4},
+			sys.NewRangeFilter(int64(rpc.FinalizedBlockNumber), int64(rpc.LatestBlockNumber), nil, nil), []common.Hash{hash3, hash4},
 		}, {
-			sys.NewRangeFilter(-3, -3, nil, nil), []common.Hash{hash3},
+			sys.NewRangeFilter(int64(rpc.FinalizedBlockNumber), int64(rpc.FinalizedBlockNumber), nil, nil), []common.Hash{hash3},
 		}, {
-			sys.NewRangeFilter(-1, -3, nil, nil), nil,
+			sys.NewRangeFilter(int64(rpc.LatestBlockNumber), int64(rpc.FinalizedBlockNumber), nil, nil), nil,
 		}, {
-			sys.NewRangeFilter(-4, -1, nil, nil), nil,
+			sys.NewRangeFilter(int64(rpc.SafeBlockNumber), int64(rpc.LatestBlockNumber), nil, nil), nil,
 		}, {
-			sys.NewRangeFilter(-4, -4, nil, nil), nil,
+			sys.NewRangeFilter(int64(rpc.SafeBlockNumber), int64(rpc.SafeBlockNumber), nil, nil), nil,
 		}, {
-			sys.NewRangeFilter(-1, -4, nil, nil), nil,
+			sys.NewRangeFilter(int64(rpc.LatestBlockNumber), int64(rpc.SafeBlockNumber), nil, nil), nil,
+		}, {
+			sys.NewRangeFilter(int64(rpc.PendingBlockNumber), int64(rpc.PendingBlockNumber), nil, nil), nil,
 		},
 	} {
 		logs, _ := tc.f.Logs(context.Background())

ethclient/ethclient.go

@@ -592,19 +592,15 @@ func toBlockNumArg(number *big.Int) string {
 	if number == nil {
 		return "latest"
 	}
-	pending := big.NewInt(-1)
-	if number.Cmp(pending) == 0 {
-		return "pending"
-	}
-	finalized := big.NewInt(int64(rpc.FinalizedBlockNumber))
-	if number.Cmp(finalized) == 0 {
-		return "finalized"
+	if number.Sign() >= 0 {
+		return hexutil.EncodeBig(number)
 	}
-	safe := big.NewInt(int64(rpc.SafeBlockNumber))
-	if number.Cmp(safe) == 0 {
-		return "safe"
+	// It's negative.
+	if number.IsInt64() {
+		return rpc.BlockNumber(number.Int64()).String()
 	}
-	return hexutil.EncodeBig(number)
+	// It's negative and large, which is invalid.
+	return fmt.Sprintf("<invalid %d>", number)
 }
 
 func toCallArg(msg ethereum.CallMsg) interface{} {

ethclient/gethclient/gethclient.go

@@ -20,6 +20,7 @@ package gethclient
 import (
 	"context"
 	"encoding/json"
+	"fmt"
 	"math/big"
 	"runtime"
 	"runtime/debug"
@@ -207,19 +208,15 @@ func toBlockNumArg(number *big.Int) string {
 	if number == nil {
 		return "latest"
 	}
-	pending := big.NewInt(-1)
-	if number.Cmp(pending) == 0 {
-		return "pending"
-	}
-	finalized := big.NewInt(int64(rpc.FinalizedBlockNumber))
-	if number.Cmp(finalized) == 0 {
-		return "finalized"
+	if number.Sign() >= 0 {
+		return hexutil.EncodeBig(number)
 	}
-	safe := big.NewInt(int64(rpc.SafeBlockNumber))
-	if number.Cmp(safe) == 0 {
-		return "safe"
+	// It's negative.
+	if number.IsInt64() {
+		return rpc.BlockNumber(number.Int64()).String()
 	}
-	return hexutil.EncodeBig(number)
+	// It's negative and large, which is invalid.
+	return fmt.Sprintf("<invalid %d>", number)
 }
 
 func toCallArg(msg ethereum.CallMsg) interface{} {

rpc/types.go

@@ -65,8 +65,8 @@ type BlockNumber int64
 const (
 	SafeBlockNumber      = BlockNumber(-4)
 	FinalizedBlockNumber = BlockNumber(-3)
-	PendingBlockNumber   = BlockNumber(-2)
-	LatestBlockNumber    = BlockNumber(-1)
+	LatestBlockNumber    = BlockNumber(-2)
+	PendingBlockNumber   = BlockNumber(-1)
 	EarliestBlockNumber  = BlockNumber(0)
 )
 
@@ -111,28 +111,36 @@ func (bn *BlockNumber) UnmarshalJSON(data []byte) error {
 	return nil
 }
 
+// Int64 returns the block number as int64.
+func (bn BlockNumber) Int64() int64 {
+	return (int64)(bn)
+}
+
 // MarshalText implements encoding.TextMarshaler. It marshals:
 // - "safe", "finalized", "latest", "earliest" or "pending" as strings
 // - other numbers as hex
 func (bn BlockNumber) MarshalText() ([]byte, error) {
+	return []byte(bn.String()), nil
+}
+
+func (bn BlockNumber) String() string {
 	switch bn {
 	case EarliestBlockNumber:
-		return []byte("earliest"), nil
+		return "earliest"
 	case LatestBlockNumber:
-		return []byte("latest"), nil
+		return "latest"
 	case PendingBlockNumber:
-		return []byte("pending"), nil
+		return "pending"
 	case FinalizedBlockNumber:
-		return []byte("finalized"), nil
+		return "finalized"
 	case SafeBlockNumber:
-		return []byte("safe"), nil
+		return "safe"
 	default:
-		return hexutil.Uint64(bn).MarshalText()
+		if bn < 0 {
+			return fmt.Sprintf("<invalid %d>", bn)
 		}
+		return hexutil.Uint64(bn).String()
 	}
-
-func (bn BlockNumber) Int64() int64 {
-	return (int64)(bn)
 }
 
 type BlockNumberOrHash struct {