rpc: support big integers as request parameters

Signed-off-by: Evgeniy Stratonikov <evgeniy@nspcc.ru>

pkg/rpc/request/param.go

@@ -7,6 +7,7 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
+	"math/big"
 	"strconv"
 	"strings"
 
@@ -115,7 +116,7 @@ func (p *Param) GetString() (string, error) {
 		if err == nil {
 			p.cache = s
 		} else {
-			var i int
+			var i int64
 			err = json.Unmarshal(p.RawMessage, &i)
 			if err == nil {
 				p.cache = i
@@ -133,8 +134,8 @@ func (p *Param) GetString() (string, error) {
 	switch t := p.cache.(type) {
 	case string:
 		return t, nil
-	case int:
+	case int64:
-		return strconv.Itoa(t), nil
+		return strconv.FormatInt(t, 10), nil
 	case bool:
 		if t {
 			return "true", nil
@@ -180,7 +181,7 @@ func (p *Param) GetBoolean() (bool, error) {
 			if err == nil {
 				p.cache = s
 			} else {
-				var i int
+				var i int64
 				err = json.Unmarshal(p.RawMessage, &i)
 				if err == nil {
 					p.cache = i
@@ -195,7 +196,7 @@ func (p *Param) GetBoolean() (bool, error) {
 		return t, nil
 	case string:
 		return t != "", nil
-	case int:
+	case int64:
 		return t != 0, nil
 	default:
 		return false, errNotABool
@@ -210,20 +211,46 @@ func (p *Param) GetIntStrict() (int, error) {
 	if p.IsNull() {
 		return 0, errNotAnInt
 	}
-	if p.cache == nil {
+	value, err := p.fillIntCache()
-		var i int
-		err := json.Unmarshal(p.RawMessage, &i)
 	if err != nil {
-			return i, errNotAnInt
+		return 0, err
 	}
-		p.cache = i
+	if i, ok := value.(int64); ok && i == int64(int(i)) {
-	}
+		return int(i), nil
-	if i, ok := p.cache.(int); ok {
-		return i, nil
 	}
 	return 0, errNotAnInt
 }
 
+func (p *Param) fillIntCache() (interface{}, error) {
+	if p.cache != nil {
+		return p.cache, nil
+	}
+
+	// We could also try unmarshalling to uint64, but JSON reliably supports numbers
+	// up to 53 bits in size.
+	var i int64
+	err := json.Unmarshal(p.RawMessage, &i)
+	if err == nil {
+		p.cache = i
+		return i, nil
+	}
+
+	var s string
+	err = json.Unmarshal(p.RawMessage, &s)
+	if err == nil {
+		p.cache = s
+		return s, nil
+	}
+
+	var b bool
+	err = json.Unmarshal(p.RawMessage, &b)
+	if err == nil {
+		p.cache = b
+		return b, nil
+	}
+	return nil, errNotAnInt
+}
+
 // GetInt returns int value of the parameter or tries to cast parameter to an int value.
 func (p *Param) GetInt() (int, error) {
 	if p == nil {
@@ -232,30 +259,16 @@ func (p *Param) GetInt() (int, error) {
 	if p.IsNull() {
 		return 0, errNotAnInt
 	}
-	if p.cache == nil {
+	value, err := p.fillIntCache()
-		var i int
+	if err != nil {
-		err := json.Unmarshal(p.RawMessage, &i)
+		return 0, err
-		if err == nil {
+	}
-			p.cache = i
+	switch t := value.(type) {
-		} else {
+	case int64:
-			var s string
+		if t == int64(int(t)) {
-			err = json.Unmarshal(p.RawMessage, &s)
+			return int(t), nil
-			if err == nil {
+		}
-				p.cache = s
-			} else {
-				var b bool
-				err = json.Unmarshal(p.RawMessage, &b)
-				if err == nil {
-					p.cache = b
-				} else {
 		return 0, errNotAnInt
-				}
-			}
-		}
-	}
-	switch t := p.cache.(type) {
-	case int:
-		return t, nil
 	case string:
 		return strconv.Atoi(t)
 	case bool:
@@ -264,7 +277,38 @@ func (p *Param) GetInt() (int, error) {
 		}
 		return 0, nil
 	default:
-		return 0, errNotAnInt
+		panic("unreachable")
+	}
+}
+
+// GetBigInt returns big-interer value of the parameter.
+func (p *Param) GetBigInt() (*big.Int, error) {
+	if p == nil {
+		return nil, errMissingParameter
+	}
+	if p.IsNull() {
+		return nil, errNotAnInt
+	}
+	value, err := p.fillIntCache()
+	if err != nil {
+		return nil, err
+	}
+	switch t := value.(type) {
+	case int64:
+		return big.NewInt(t), nil
+	case string:
+		bi, ok := new(big.Int).SetString(t, 10)
+		if !ok {
+			return nil, errNotAnInt
+		}
+		return bi, nil
+	case bool:
+		if t {
+			return big.NewInt(1), nil
+		}
+		return new(big.Int), nil
+	default:
+		panic("unreachable")
 	}
 }
 

pkg/rpc/request/param_test.go

@@ -5,6 +5,8 @@ import (
 	"encoding/hex"
 	"encoding/json"
 	"fmt"
+	"math"
+	"math/big"
 	"testing"
 
 	"github.com/nspcc-dev/neo-go/pkg/core/transaction"
@@ -190,6 +192,48 @@ func TestParam_UnmarshalJSON(t *testing.T) {
 	}
 }
 
+func TestGetBigInt(t *testing.T) {
+	maxUint64 := new(big.Int).SetUint64(math.MaxUint64)
+	minInt64 := big.NewInt(math.MinInt64)
+	testCases := []struct {
+		raw      string
+		expected *big.Int
+	}{
+		{"true", big.NewInt(1)},
+		{"false", new(big.Int)},
+		{"42", big.NewInt(42)},
+		{`"` + minInt64.String() + `"`, minInt64},
+		{`"` + maxUint64.String() + `"`, maxUint64},
+		{`"` + minInt64.String() + `000"`, new(big.Int).Mul(minInt64, big.NewInt(1000))},
+		{`"` + maxUint64.String() + `000"`, new(big.Int).Mul(maxUint64, big.NewInt(1000))},
+		{`"abc"`, nil},
+		{`[]`, nil},
+		{`null`, nil},
+	}
+
+	for _, tc := range testCases {
+		var p Param
+		require.NoError(t, json.Unmarshal([]byte(tc.raw), &p))
+
+		actual, err := p.GetBigInt()
+		if tc.expected == nil {
+			require.Error(t, err)
+			continue
+		}
+		require.NoError(t, err)
+		require.Equal(t, tc.expected, actual)
+
+		expected := tc.expected.Int64()
+		actualInt, err := p.GetInt()
+		if !actual.IsInt64() || int64(int(expected)) != expected {
+			require.Error(t, err)
+		} else {
+			require.NoError(t, err)
+			require.Equal(t, int(expected), actualInt)
+		}
+	}
+}
+
 func TestGetWitness(t *testing.T) {
 	accountHash, err := util.Uint160DecodeStringLE("cadb3dc2faa3ef14a13b619c9a43124755aa2569")
 	require.NoError(t, err)

pkg/rpc/request/txBuilder.go

@@ -63,11 +63,11 @@ func ExpandArrayIntoScript(script *io.BinWriter, slice []Param) error {
 			}
 			emit.Bytes(script, key.Bytes())
 		case smartcontract.IntegerType:
-			val, err := fp.Value.GetInt()
+			bi, err := fp.Value.GetBigInt()
 			if err != nil {
 				return err
 			}
-			emit.Int(script, int64(val))
+			emit.BigInt(script, bi)
 		case smartcontract.BoolType:
 			val, err := fp.Value.GetBoolean() // not GetBooleanStrict(), because that's the way C# code works
 			if err != nil {

pkg/rpc/request/tx_builder_test.go

@@ -3,6 +3,7 @@ package request
 import (
 	"encoding/hex"
 	"fmt"
+	"math/big"
 	"testing"
 
 	"github.com/nspcc-dev/neo-go/pkg/io"
@@ -100,6 +101,10 @@ func TestInvocationScriptCreationBad(t *testing.T) {
 }
 
 func TestExpandArrayIntoScript(t *testing.T) {
+	bi := new(big.Int).Lsh(big.NewInt(1), 254)
+	rawInt := make([]byte, 32)
+	rawInt[31] = 0x40
+
 	testCases := []struct {
 		Input    []Param
 		Expected []byte
@@ -112,6 +117,10 @@ func TestExpandArrayIntoScript(t *testing.T) {
 			Input:    []Param{{RawMessage: []byte(`{"type": "Array", "value": [{"type": "String", "value": "a"}]}`)}},
 			Expected: []byte{byte(opcode.PUSHDATA1), 1, byte('a'), byte(opcode.PUSH1), byte(opcode.PACK)},
 		},
+		{
+			Input:    []Param{{RawMessage: []byte(`{"type": "Integer", "value": "` + bi.String() + `"}`)}},
+			Expected: append([]byte{byte(opcode.PUSHINT256)}, rawInt...),
+		},
 	}
 	for _, c := range testCases {
 		script := io.NewBufBinWriter()

pkg/vm/emit/emit.go

@@ -52,18 +52,38 @@ func padRight(s int, buf []byte) []byte {
 
 // Int emits a int type to the given buffer.
 func Int(w *io.BinWriter, i int64) {
+	if smallInt(w, i) {
+		return
+	}
+	bigInt(w, big.NewInt(i), false)
+}
+
+// BigInt emits big-integer to the given buffer.
+func BigInt(w *io.BinWriter, n *big.Int) {
+	bigInt(w, n, true)
+}
+
+func smallInt(w *io.BinWriter, i int64) bool {
 	switch {
 	case i == -1:
 		Opcodes(w, opcode.PUSHM1)
 	case i >= 0 && i < 16:
-		val := opcode.Opcode(int(opcode.PUSH1) - 1 + int(i))
+		val := opcode.Opcode(int(opcode.PUSH0) + int(i))
 		Opcodes(w, val)
 	default:
-		bigInt(w, big.NewInt(i))
+		return false
 	}
+	return true
+}
+
+func bigInt(w *io.BinWriter, n *big.Int, trySmall bool) {
+	if w.Err != nil {
+		return
+	}
+	if trySmall && n.IsInt64() && smallInt(w, n.Int64()) {
+		return
 	}
 
-func bigInt(w *io.BinWriter, n *big.Int) {
 	buf := bigint.ToPreallocatedBytes(n, make([]byte, 0, 32))
 	if len(buf) == 0 {
 		Opcodes(w, opcode.PUSH0)
@@ -101,7 +121,7 @@ func Array(w *io.BinWriter, es ...interface{}) {
 		case int:
 			Int(w, int64(e))
 		case *big.Int:
-			bigInt(w, e)
+			BigInt(w, e)
 		case string:
 			String(w, e)
 		case util.Uint160: