Merge pull request #1724 from jatelReview/feature-mainnet-launch

fix wasm external function platon_block_hash get too low block hash.

core/vm/wagon_runtime.go

@@ -826,7 +826,19 @@ func GasPrice(proc *exec.Process, gasPrice uint32) uint32 {
 func BlockHash(proc *exec.Process, num uint64, dst uint32) {
 	ctx := proc.HostCtx().(*VMContext)
 	checkGas(ctx, GasExtStep)
-	blockHash := ctx.evm.GetHash(num)
+
+	// Add get block height limit, same as evm opBlockhash
+	var upper, lower uint64
+	upper = ctx.evm.BlockNumber.Uint64()
+	if upper < 257 {
+		lower = 0
+	} else {
+		lower = upper - 256
+	}
+	var blockHash common.Hash
+	if num >= lower && num < upper {
+		blockHash = ctx.evm.GetHash(num)
+	}
 	_, err := proc.WriteAt(blockHash.Bytes(), int64(dst))
 	if nil != err {
 		panic(err)

core/vm/wagon_runtime_test.go

@@ -5,6 +5,7 @@ import (
 	"context"
 	"crypto/sha256"
 	"encoding/binary"
+	"github.com/PlatONnetwork/PlatON-Go/common/hexutil"
 	"hash/fnv"
 	"io/ioutil"
 	"math/big"
@@ -50,6 +51,7 @@ var testCase = []*Case{
 	{
 		ctx: &VMContext{
 			evm: &EVM{Context: Context{
+				BlockNumber: big.NewInt(99),
 				GetHash: func(u uint64) common.Hash {
 					return common.Hash{1, 2, 3}
 				}},
@@ -1367,6 +1369,23 @@ var testCase = []*Case{
 	},
 }
 
+var initExternalGas = uint64(10000000)
+
+type testContract struct{}
+
+func (testContract) Address() common.Address {
+	return common.Address{}
+}
+
+func newTestVM(evm *EVM) *exec.VM {
+	code := "0x0061736d010000000108026000006000017f03030200010405017001010105030100020615037f01418088040b7f00418088040b7f004180080b072c04066d656d6f727902000b5f5f686561705f6261736503010a5f5f646174615f656e640302046d61696e00010a090202000b0400412a0b004d0b2e64656275675f696e666f3d0000000400000000000401000000000c0023000000000000004300000005000000040000000205000000040000005c000000010439000000036100000005040000100e2e64656275675f6d6163696e666f0000400d2e64656275675f616262726576011101250e1305030e10171b0e110112060000022e0011011206030e3a0b3b0b49133f190000032400030e3e0b0b0b000000005e0b2e64656275675f6c696e654e000000040037000000010101fb0e0d0001010101000000010000012f746d702f6275696c645f7664717864336f336f316c2e24000066696c652e630001000000000502050000001505030a3d020100010100700a2e64656275675f737472636c616e672076657273696f6e20382e302e3020287472756e6b2033343139363029002f746d702f6275696c645f7664717864336f336f316c2e242f66696c652e63002f746d702f6275696c645f7664717864336f336f316c2e24006d61696e00696e74000021046e616d65011a0200115f5f7761736d5f63616c6c5f63746f727301046d61696e"
+	module, _ := ReadWasmModule(hexutil.MustDecode(code), false)
+
+	vm, _ := exec.NewVM(module.RawModule)
+	vm.SetHostCtx(&VMContext{evm: evm, contract: NewContract(&testContract{}, &testContract{}, big.NewInt(0), initExternalGas)})
+	return vm
+}
+
 func TestExternalFunction(t *testing.T) {
 	buf, err := ioutil.ReadFile("./testdata/external.wasm")
 	assert.Nil(t, err)
@@ -1557,3 +1576,39 @@ func checkContractRet(ret []byte) bool {
 	}
 	return true
 }
+
+func TestGetBlockHash(t *testing.T) {
+
+	testBlockHash := common.BytesToHash([]byte{1, 2, 3, 4})
+	newProc := func(blockNumber int64) *exec.Process {
+		return exec.NewProcess(newTestVM(&EVM{
+			Context: Context{
+				GetHash: func(u uint64) common.Hash {
+					return testBlockHash
+				},
+				BlockNumber: big.NewInt(blockNumber),
+			},
+		}))
+	}
+
+	type TestCase struct {
+		blockNumber int64
+		getNumber   uint64
+		expect      common.Hash
+	}
+	cases := []TestCase{
+		{1, 123, common.Hash{}},
+		{123, 123, common.Hash{}},
+		{123, 122, testBlockHash},
+		{1024, 122, common.Hash{}},
+		{1024, 1024 - 256, testBlockHash},
+	}
+	for _, c := range cases {
+		proc := newProc(c.blockNumber)
+		BlockHash(proc, c.getNumber, 1024)
+		res := common.Hash{}
+		proc.ReadAt(res[:], 1024)
+		assert.Equal(t, c.expect, res)
+		assert.Equal(t, initExternalGas-GasExtStep, proc.HostCtx().(*VMContext).contract.Gas)
+	}
+}