core/vm: implement contract storage and script retrieval

Fixes script invocations via the APPCALL instruction. Adjust contract state
field types accordingly.

pkg/core/blockchain.go

@@ -313,6 +313,7 @@ func (bc *Blockchain) storeBlock(block *Block) error {
 		spentCoins   = make(SpentCoins)
 		accounts     = make(Accounts)
 		assets       = make(Assets)
+		contracts    = make(Contracts)
 	)
 
 	if err := storeAsBlock(batch, block, 0); err != nil {
@@ -399,7 +400,7 @@ func (bc *Blockchain) storeBlock(block *Block) error {
 				Email:       t.Email,
 				Description: t.Description,
 			}
-			_ = contract
+			contracts[contract.ScriptHash()] = contract
 
 		case *transaction.InvocationTX:
 		}
@@ -418,6 +419,9 @@ func (bc *Blockchain) storeBlock(block *Block) error {
 	if err := assets.commit(batch); err != nil {
 		return err
 	}
+	if err := contracts.commit(batch); err != nil {
+		return err
+	}
 	if err := bc.memStore.PutBatch(batch); err != nil {
 		return err
 	}
@@ -643,6 +647,33 @@ func getAssetStateFromStore(s storage.Store, assetID util.Uint256) *AssetState {
 	return &a
 }
 
+// GetContractState returns contract by its script hash.
+func (bc *Blockchain) GetContractState(hash util.Uint160) *ContractState {
+	cs := getContractStateFromStore(bc.memStore, hash)
+	if cs == nil {
+		cs = getContractStateFromStore(bc.Store, hash)
+	}
+	return cs
+}
+
+// getContractStateFromStore returns contract state as recorded in the given
+// store by the given script hash.
+func getContractStateFromStore(s storage.Store, hash util.Uint160) *ContractState {
+	key := storage.AppendPrefix(storage.STContract, hash.Bytes())
+	contractBytes, err := s.Get(key)
+	if err != nil {
+		return nil
+	}
+	var c ContractState
+	r := io.NewBinReaderFromBuf(contractBytes)
+	c.DecodeBinary(r)
+	if r.Err != nil || c.ScriptHash() != hash {
+		return nil
+	}
+
+	return &c
+}
+
 // GetAccountState returns the account state from its script hash
 func (bc *Blockchain) GetAccountState(scriptHash util.Uint160) *AccountState {
 	as, err := getAccountStateFromStore(bc.memStore, scriptHash)
@@ -1001,6 +1032,13 @@ func (bc *Blockchain) VerifyWitnesses(t *transaction.Transaction) error {
 
 		vm := vm.New(vm.ModeMute)
 		vm.SetCheckedHash(t.VerificationHash().Bytes())
+		vm.SetScriptGetter(func(hash util.Uint160) []byte {
+			cs := bc.GetContractState(hash)
+			if cs == nil {
+				return nil
+			}
+			return cs.Script
+		})
 		vm.LoadScript(verification)
 		vm.LoadScript(witnesses[i].InvocationScript)
 		vm.Run()

pkg/core/contract_state.go

@@ -1,16 +1,22 @@
 package core
 
 import (
+	"github.com/CityOfZion/neo-go/pkg/core/storage"
+	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
+	"github.com/CityOfZion/neo-go/pkg/io"
 	"github.com/CityOfZion/neo-go/pkg/smartcontract"
 	"github.com/CityOfZion/neo-go/pkg/util"
 )
 
+// Contracts is a mapping between scripthash and ContractState.
+type Contracts map[util.Uint160]*ContractState
+
 // ContractState holds information about a smart contract in the NEO blockchain.
 type ContractState struct {
 	Script           []byte
 	ParamList        []smartcontract.ParamType
 	ReturnType       smartcontract.ParamType
-	Properties       []int
+	Properties       []byte
 	Name             string
 	CodeVersion      string
 	Author           string
@@ -21,3 +27,69 @@ type ContractState struct {
 
 	scriptHash util.Uint160
 }
+
+// commit flushes all contracts to the given storage.Batch.
+func (a Contracts) commit(b storage.Batch) error {
+	buf := io.NewBufBinWriter()
+	for hash, contract := range a {
+		contract.EncodeBinary(buf.BinWriter)
+		if buf.Err != nil {
+			return buf.Err
+		}
+		key := storage.AppendPrefix(storage.STContract, hash.Bytes())
+		b.Put(key, buf.Bytes())
+		buf.Reset()
+	}
+	return nil
+}
+
+// DecodeBinary implements Serializable interface.
+func (a *ContractState) DecodeBinary(br *io.BinReader) {
+	a.Script = br.ReadBytes()
+	paramBytes := br.ReadBytes()
+	a.ParamList = make([]smartcontract.ParamType, len(paramBytes))
+	for k := range paramBytes {
+		a.ParamList[k] = smartcontract.ParamType(paramBytes[k])
+	}
+	br.ReadLE(&a.ReturnType)
+	a.Properties = br.ReadBytes()
+	a.Name = br.ReadString()
+	a.CodeVersion = br.ReadString()
+	a.Author = br.ReadString()
+	a.Email = br.ReadString()
+	a.Description = br.ReadString()
+	br.ReadLE(&a.HasStorage)
+	br.ReadLE(&a.HasDynamicInvoke)
+	a.createHash()
+}
+
+// EncodeBinary implements Serializable interface.
+func (a *ContractState) EncodeBinary(bw *io.BinWriter) {
+	bw.WriteBytes(a.Script)
+	bw.WriteVarUint(uint64(len(a.ParamList)))
+	for k := range a.ParamList {
+		bw.WriteLE(a.ParamList[k])
+	}
+	bw.WriteLE(a.ReturnType)
+	bw.WriteBytes(a.Properties)
+	bw.WriteString(a.Name)
+	bw.WriteString(a.CodeVersion)
+	bw.WriteString(a.Author)
+	bw.WriteString(a.Email)
+	bw.WriteString(a.Description)
+	bw.WriteLE(a.HasStorage)
+	bw.WriteLE(a.HasDynamicInvoke)
+}
+
+// ScriptHash returns a contract script hash.
+func (a *ContractState) ScriptHash() util.Uint160 {
+	if a.scriptHash.Equals(util.Uint160{}) {
+		a.createHash()
+	}
+	return a.scriptHash
+}
+
+// createHash creates contract script hash.
+func (a *ContractState) createHash() {
+	a.scriptHash = hash.Hash160(a.Script)
+}

pkg/core/contract_state_test.go

@@ -0,0 +1,39 @@
+package core
+
+import (
+	"testing"
+
+	"github.com/CityOfZion/neo-go/pkg/crypto/hash"
+	"github.com/CityOfZion/neo-go/pkg/io"
+	"github.com/CityOfZion/neo-go/pkg/smartcontract"
+	"github.com/stretchr/testify/assert"
+)
+
+func TestEncodeDecodeContractState(t *testing.T) {
+	script := []byte("testscript")
+
+	contract := &ContractState{
+		Script:           script,
+		ParamList:        []smartcontract.ParamType{smartcontract.StringType, smartcontract.IntegerType, smartcontract.Hash160Type},
+		ReturnType:       smartcontract.BoolType,
+		Properties:       []byte("smth"),
+		Name:             "Contracto",
+		CodeVersion:      "1.0.0",
+		Author:           "Joe Random",
+		Email:            "joe@example.com",
+		Description:      "Test contract",
+		HasStorage:       true,
+		HasDynamicInvoke: false,
+	}
+
+	assert.Equal(t, hash.Hash160(script), contract.ScriptHash())
+	buf := io.NewBufBinWriter()
+	contract.EncodeBinary(buf.BinWriter)
+	assert.Nil(t, buf.Err)
+	contractDecoded := &ContractState{}
+	r := io.NewBinReaderFromBuf(buf.Bytes())
+	contractDecoded.DecodeBinary(r)
+	assert.Nil(t, r.Err)
+	assert.Equal(t, contract, contractDecoded)
+	assert.Equal(t, contract.ScriptHash(), contractDecoded.ScriptHash())
+}

pkg/smartcontract/param_context.go

@@ -3,7 +3,7 @@ package smartcontract
 import "github.com/CityOfZion/neo-go/pkg/util"
 
 // ParamType represent the Type of the contract parameter
-type ParamType int
+type ParamType byte
 
 // A list of supported smart contract parameter types.
 const (

pkg/vm/vm.go

@@ -35,8 +35,8 @@ type VM struct {
 	// registered interop hooks.
 	interop map[string]InteropFunc
 
-	// scripts loaded in memory.
+	// callback to get scripts.
-	scripts map[util.Uint160][]byte
+	getScript func(util.Uint160) []byte
 
 	istack *Stack // invocation stack.
 	estack *Stack // execution stack.
@@ -51,12 +51,12 @@ type VM struct {
 // New returns a new VM object ready to load .avm bytecode scripts.
 func New(mode Mode) *VM {
 	vm := &VM{
-		interop: make(map[string]InteropFunc),
+		interop:   make(map[string]InteropFunc),
-		scripts: make(map[util.Uint160][]byte),
+		getScript: nil,
-		state:   haltState,
+		state:     haltState,
-		istack:  NewStack("invocation"),
+		istack:    NewStack("invocation"),
-		estack:  NewStack("evaluation"),
+		estack:    NewStack("evaluation"),
-		astack:  NewStack("alt"),
+		astack:    NewStack("alt"),
 	}
 	if mode == ModeMute {
 		vm.mute = true
@@ -248,6 +248,11 @@ func (v *VM) SetCheckedHash(h []byte) {
 	copy(v.checkhash, h)
 }
 
+// SetScriptGetter sets the script getter for CALL instructions.
+func (v *VM) SetScriptGetter(gs func(util.Uint160) []byte) {
+	v.getScript = gs
+}
+
 // execute performs an instruction cycle in the VM. Acting on the instruction (opcode).
 func (v *VM) execute(ctx *Context, op Instruction) {
 	// Instead of polluting the whole VM logic with error handling, we will recover
@@ -850,8 +855,8 @@ func (v *VM) execute(ctx *Context, op Instruction) {
 		}
 
 	case APPCALL, TAILCALL:
-		if len(v.scripts) == 0 {
+		if v.getScript == nil {
-			panic("script table is empty")
+			panic("no getScript callback is set up")
 		}
 
 		hash, err := util.Uint160DecodeBytes(ctx.readBytes(20))
@@ -859,8 +864,8 @@ func (v *VM) execute(ctx *Context, op Instruction) {
 			panic(err)
 		}
 
-		script, ok := v.scripts[hash]
+		script := v.getScript(hash)
-		if !ok {
+		if script == nil {
 			panic("could not find script")
 		}
 

pkg/vm/vm_test.go

@@ -1000,7 +1000,12 @@ func TestAppCall(t *testing.T) {
 	prog = append(prog, byte(RET))
 
 	vm := load(prog)
-	vm.scripts[hash] = makeProgram(DEPTH)
+	vm.SetScriptGetter(func(in util.Uint160) []byte {
+		if in.Equals(hash) {
+			return makeProgram(DEPTH)
+		}
+		return nil
+	})
 	vm.estack.PushVal(2)
 
 	vm.Run()