Merge pull request #2003 from obscuren/abi-calling

accounts/abi: added output parsing & added call mechanism

6 files changed, 243 insertions, 88 deletions

diff --git a/accounts/abi/abi.go b/accounts/abi/abi.go
index 3f05bfe2d..635dc43fe 100644
--- a/accounts/abi/abi.go
+++ b/accounts/abi/abi.go
@@ -20,75 +20,17 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
-	"strings"
+	"math"
 
-	"github.com/ethereum/go-ethereum/crypto"
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
 )
 
-// Callable method given a `Name` and whether the method is a constant.
-// If the method is `Const` no transaction needs to be created for this
-// particular Method call. It can easily be simulated using a local VM.
-// For example a `Balance()` method only needs to retrieve something
-// from the storage and therefor requires no Tx to be send to the
-// network. A method such as `Transact` does require a Tx and thus will
-// be flagged `true`.
-// Input specifies the required input parameters for this gives method.
-type Method struct {
-	Name   string
-	Const  bool
-	Inputs []Argument
-	Return Type // not yet implemented
-}
-
-// Returns the methods string signature according to the ABI spec.
-//
-// Example
-//
-//     function foo(uint32 a, int b)    =    "foo(uint32,int256)"
-//
-// Please note that "int" is substitute for its canonical representation "int256"
-func (m Method) String() (out string) {
-	out += m.Name
-	types := make([]string, len(m.Inputs))
-	i := 0
-	for _, input := range m.Inputs {
-		types[i] = input.Type.String()
-		i++
-	}
-	out += "(" + strings.Join(types, ",") + ")"
-
-	return
-}
-
-func (m Method) Id() []byte {
-	return crypto.Sha3([]byte(m.String()))[:4]
-}
-
-// Argument holds the name of the argument and the corresponding type.
-// Types are used when packing and testing arguments.
-type Argument struct {
-	Name string
-	Type Type
-}
-
-func (a *Argument) UnmarshalJSON(data []byte) error {
-	var extarg struct {
-		Name string
-		Type string
-	}
-	err := json.Unmarshal(data, &extarg)
-	if err != nil {
-		return fmt.Errorf("argument json err: %v", err)
-	}
-
-	a.Type, err = NewType(extarg.Type)
-	if err != nil {
-		return err
-	}
-	a.Name = extarg.Name
-
-	return nil
-}
+// Executer is an executer method for performing state executions. It takes one
+// argument which is the input data and expects output data to be returned as
+// multiple 32 byte word length concatenated slice
+type Executer func(datain []byte) []byte
 
 // The ABI holds information about a contract's context and available
 // invokable methods. It will allow you to type check function calls and
@@ -97,6 +39,18 @@ type ABI struct {
 	Methods map[string]Method
 }
 
+// JSON returns a parsed ABI interface and error if it failed.
+func JSON(reader io.Reader) (ABI, error) {
+	dec := json.NewDecoder(reader)
+
+	var abi ABI
+	if err := dec.Decode(&abi); err != nil {
+		return ABI{}, err
+	}
+
+	return abi, nil
+}
+
 // tests, tests whether the given input would result in a successful
 // call. Checks argument list count and matches input to `input`.
 func (abi ABI) pack(name string, args ...interface{}) ([]byte, error) {
@@ -145,6 +99,55 @@ func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
 	return packed, nil
 }
 
+// toGoType parses the input and casts it to the proper type defined by the ABI
+// argument in t.
+func toGoType(t Argument, input []byte) interface{} {
+	switch t.Type.T {
+	case IntTy:
+		return common.BytesToBig(input)
+	case UintTy:
+		return common.BytesToBig(input)
+	case BoolTy:
+		return common.BytesToBig(input).Uint64() > 0
+	case AddressTy:
+		return common.BytesToAddress(input)
+	case HashTy:
+		return common.BytesToHash(input)
+	}
+	return nil
+}
+
+// Call executes a call and attemps to parse the return values and returns it as
+// an interface. It uses the executer method to perform the actual call since
+// the abi knows nothing of the lower level calling mechanism.
+//
+// Call supports all abi types and includes multiple return values. When only
+// one item is returned a single interface{} will be returned, if a contract
+// method returns multiple values an []interface{} slice is returned.
+func (abi ABI) Call(executer Executer, name string, args ...interface{}) interface{} {
+	callData, err := abi.Pack(name, args...)
+	if err != nil {
+		glog.V(logger.Debug).Infoln("pack error:", err)
+		return nil
+	}
+
+	output := executer(callData)
+
+	method := abi.Methods[name]
+	ret := make([]interface{}, int(math.Max(float64(len(method.Outputs)), float64(len(output)/32))))
+	for i := 0; i < len(ret); i += 32 {
+		index := i / 32
+		ret[index] = toGoType(method.Outputs[index], output[i:i+32])
+	}
+
+	// return single interface
+	if len(ret) == 1 {
+		return ret[0]
+	}
+
+	return ret
+}
+
 func (abi *ABI) UnmarshalJSON(data []byte) error {
 	var methods []Method
 	if err := json.Unmarshal(data, &methods); err != nil {
@@ -158,14 +161,3 @@ func (abi *ABI) UnmarshalJSON(data []byte) error {
 
 	return nil
 }
-
-func JSON(reader io.Reader) (ABI, error) {
-	dec := json.NewDecoder(reader)
-
-	var abi ABI
-	if err := dec.Decode(&abi); err != nil {
-		return ABI{}, err
-	}
-
-	return abi, nil
-}
diff --git a/accounts/abi/abi_test.go b/accounts/abi/abi_test.go
index 96dd3ee62..d514fb8c7 100644
--- a/accounts/abi/abi_test.go
+++ b/accounts/abi/abi_test.go
@@ -92,12 +92,12 @@ func TestReader(t *testing.T) {
 	exp := ABI{
 		Methods: map[string]Method{
 			"balance": Method{
-				"balance", true, nil, Type{},
+				"balance", true, nil, nil,
 			},
 			"send": Method{
 				"send", false, []Argument{
 					Argument{"amount", Uint256},
-				}, Type{},
+				}, nil,
 			},
 		},
 	}
@@ -238,10 +238,10 @@ func TestTestAddress(t *testing.T) {
 func TestMethodSignature(t *testing.T) {
 	String, _ := NewType("string")
 	String32, _ := NewType("string32")
-	m := Method{"foo", false, []Argument{Argument{"bar", String32}, Argument{"baz", String}}, Type{}}
+	m := Method{"foo", false, []Argument{Argument{"bar", String32}, Argument{"baz", String}}, nil}
 	exp := "foo(string32,string)"
-	if m.String() != exp {
-		t.Error("signature mismatch", exp, "!=", m.String())
+	if m.Sig() != exp {
+		t.Error("signature mismatch", exp, "!=", m.Sig())
 	}
 
 	idexp := crypto.Sha3([]byte(exp))[:4]
@@ -250,10 +250,10 @@ func TestMethodSignature(t *testing.T) {
 	}
 
 	uintt, _ := NewType("uint")
-	m = Method{"foo", false, []Argument{Argument{"bar", uintt}}, Type{}}
+	m = Method{"foo", false, []Argument{Argument{"bar", uintt}}, nil}
 	exp = "foo(uint256)"
-	if m.String() != exp {
-		t.Error("signature mismatch", exp, "!=", m.String())
+	if m.Sig() != exp {
+		t.Error("signature mismatch", exp, "!=", m.Sig())
 	}
 }
 
@@ -393,3 +393,34 @@ func TestBytes(t *testing.T) {
 		t.Error("expected error")
 	}
 }
+
+func TestReturn(t *testing.T) {
+	const definition = `[
+	{ "name" : "balance", "const" : true, "inputs" : [], "outputs" : [ { "name": "", "type": "hash" } ] },
+	{ "name" : "name", "const" : true, "inputs" : [], "outputs" : [ { "name": "", "type": "address" } ] }
+
+]`
+
+	abi, err := JSON(strings.NewReader(definition))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	r := abi.Call(func([]byte) []byte {
+		t := make([]byte, 32)
+		t[0] = 1
+		return t
+	}, "balance")
+	if _, ok := r.(common.Hash); !ok {
+		t.Errorf("expected type common.Hash, got %T", r)
+	}
+
+	r = abi.Call(func([]byte) []byte {
+		t := make([]byte, 32)
+		t[0] = 1
+		return t
+	}, "name")
+	if _, ok := r.(common.Address); !ok {
+		t.Errorf("expected type common.Address, got %T", r)
+	}
+}
diff --git a/accounts/abi/argument.go b/accounts/abi/argument.go
new file mode 100644
index 000000000..8907b2979
--- /dev/null
+++ b/accounts/abi/argument.go
@@ -0,0 +1,48 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package abi
+
+import (
+	"encoding/json"
+	"fmt"
+)
+
+// Argument holds the name of the argument and the corresponding type.
+// Types are used when packing and testing arguments.
+type Argument struct {
+	Name string
+	Type Type
+}
+
+func (a *Argument) UnmarshalJSON(data []byte) error {
+	var extarg struct {
+		Name string
+		Type string
+	}
+	err := json.Unmarshal(data, &extarg)
+	if err != nil {
+		return fmt.Errorf("argument json err: %v", err)
+	}
+
+	a.Type, err = NewType(extarg.Type)
+	if err != nil {
+		return err
+	}
+	a.Name = extarg.Name
+
+	return nil
+}
diff --git a/accounts/abi/method.go b/accounts/abi/method.go
new file mode 100644
index 000000000..63194e788
--- /dev/null
+++ b/accounts/abi/method.go
@@ -0,0 +1,76 @@
+// Copyright 2015 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package abi
+
+import (
+	"fmt"
+	"strings"
+
+	"github.com/ethereum/go-ethereum/crypto"
+)
+
+// Callable method given a `Name` and whether the method is a constant.
+// If the method is `Const` no transaction needs to be created for this
+// particular Method call. It can easily be simulated using a local VM.
+// For example a `Balance()` method only needs to retrieve something
+// from the storage and therefor requires no Tx to be send to the
+// network. A method such as `Transact` does require a Tx and thus will
+// be flagged `true`.
+// Input specifies the required input parameters for this gives method.
+type Method struct {
+	Name    string
+	Const   bool
+	Inputs  []Argument
+	Outputs []Argument
+}
+
+// Sig returns the methods string signature according to the ABI spec.
+//
+// Example
+//
+//     function foo(uint32 a, int b)    =    "foo(uint32,int256)"
+//
+// Please note that "int" is substitute for its canonical representation "int256"
+func (m Method) Sig() string {
+	types := make([]string, len(m.Inputs))
+	i := 0
+	for _, input := range m.Inputs {
+		types[i] = input.Type.String()
+		i++
+	}
+	return fmt.Sprintf("%v(%v)", m.Name, strings.Join(types, ","))
+}
+
+func (m Method) String() string {
+	inputs := make([]string, len(m.Inputs))
+	for i, input := range m.Inputs {
+		inputs[i] = fmt.Sprintf("%v %v", input.Name, input.Type)
+	}
+	outputs := make([]string, len(m.Outputs))
+	for i, output := range m.Outputs {
+		if len(output.Name) > 0 {
+			outputs[i] = fmt.Sprintf("%v ", output.Name)
+		}
+		outputs[i] += output.Type.String()
+	}
+
+	return fmt.Sprintf("function %v(%v) returns(%v)", m.Name, strings.Join(inputs, ", "), strings.Join(outputs, ", "))
+}
+
+func (m Method) Id() []byte {
+	return crypto.Sha3([]byte(m.Sig()))[:4]
+}
diff --git a/accounts/abi/numbers.go b/accounts/abi/numbers.go
index 2a7049425..c37cd5f68 100644
--- a/accounts/abi/numbers.go
+++ b/accounts/abi/numbers.go
@@ -37,6 +37,8 @@ var int8_t = reflect.TypeOf(int8(0))
 var int16_t = reflect.TypeOf(int16(0))
 var int32_t = reflect.TypeOf(int32(0))
 var int64_t = reflect.TypeOf(int64(0))
+var hash_t = reflect.TypeOf(common.Hash{})
+var address_t = reflect.TypeOf(common.Address{})
 
 var uint_ts = reflect.TypeOf([]uint(nil))
 var uint8_ts = reflect.TypeOf([]uint8(nil))
diff --git a/accounts/abi/type.go b/accounts/abi/type.go
index 16d7491e7..8f0238fc9 100644
--- a/accounts/abi/type.go
+++ b/accounts/abi/type.go
@@ -31,6 +31,7 @@ const (
 	BoolTy
 	SliceTy
 	AddressTy
+	HashTy
 	RealTy
 )
 
@@ -121,7 +122,7 @@ func NewType(t string) (typ Type, err error) {
 			typ.Kind = reflect.Invalid
 		case "address":
 			typ.Kind = reflect.Slice
-			typ.Type = byte_ts
+			typ.Type = address_t
 			typ.Size = 20
 			typ.T = AddressTy
 		case "string":
@@ -130,6 +131,11 @@ func NewType(t string) (typ Type, err error) {
 			if vsize > 0 {
 				typ.Size = 32
 			}
+		case "hash":
+			typ.Kind = reflect.Slice
+			typ.Size = 32
+			typ.Type = hash_t
+			typ.T = HashTy
 		case "bytes":
 			typ.Kind = reflect.Slice
 			typ.Type = byte_ts
@@ -206,9 +212,9 @@ func (t Type) pack(v interface{}) ([]byte, error) {
 		}
 	case reflect.Array:
 		if v, ok := value.Interface().(common.Address); ok {
-			return t.pack(v[:])
+			return common.LeftPadBytes(v[:], 32), nil
 		} else if v, ok := value.Interface().(common.Hash); ok {
-			return t.pack(v[:])
+			return v[:], nil
 		}
 	}