Merge pull request #2396 from obscuren/abi-slices

abi: support for input and output slices & removed support for implicit type conversion

accounts/abi/abi.go

@@ -20,6 +20,7 @@ import (
 	"encoding/json"
 	"fmt"
 	"io"
+	"math/big"
 	"reflect"
 	"strings"
 
@@ -63,9 +64,8 @@ func (abi ABI) pack(method Method, args ...interface{}) ([]byte, error) {
 			return nil, fmt.Errorf("`%s` %v", method.Name, err)
 		}
 
-		// check for a string or bytes input type
+		// check for a slice type (string, bytes, slice)
-		switch input.Type.T {
+		if input.Type.T == StringTy || input.Type.T == BytesTy || input.Type.IsSlice {
-		case StringTy, BytesTy:
 			// calculate the offset
 			offset := len(method.Inputs)*32 + len(variableInput)
 			// set the offset
@@ -73,7 +73,7 @@ func (abi ABI) pack(method Method, args ...interface{}) ([]byte, error) {
 			// Append the packed output to the variable input. The variable input
 			// will be appended at the end of the input.
 			variableInput = append(variableInput, packed...)
-		default:
+		} else {
 			// append the packed value to the input
 			ret = append(ret, packed...)
 		}
@@ -117,11 +117,80 @@ func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
 	return append(method.Id(), arguments...), nil
 }
 
+// toGoSliceType prses the input and casts it to the proper slice defined by the ABI
+// argument in T.
+func toGoSlice(i int, t Argument, output []byte) (interface{}, error) {
+	index := i * 32
+	// The slice must, at very least be large enough for the index+32 which is exactly the size required
+	// for the [offset in output, size of offset].
+	if index+32 > len(output) {
+		return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), index+32)
+	}
+
+	// first we need to create a slice of the type
+	var refSlice reflect.Value
+	switch t.Type.T {
+	case IntTy, UintTy, BoolTy: // int, uint, bool can all be of type big int.
+		refSlice = reflect.ValueOf([]*big.Int(nil))
+	case AddressTy: // address must be of slice Address
+		refSlice = reflect.ValueOf([]common.Address(nil))
+	case HashTy: // hash must be of slice hash
+		refSlice = reflect.ValueOf([]common.Hash(nil))
+	default: // no other types are supported
+		return nil, fmt.Errorf("abi: unsupported slice type %v", t.Type.T)
+	}
+	// get the offset which determines the start of this array ...
+	offset := int(common.BytesToBig(output[index : index+32]).Uint64())
+	if offset+32 > len(output) {
+		return nil, fmt.Errorf("abi: cannot marshal in to go slice: offset %d would go over slice boundary (len=%d)", len(output), offset+32)
+	}
+
+	slice := output[offset:]
+	// ... starting with the size of the array in elements ...
+	size := int(common.BytesToBig(slice[:32]).Uint64())
+	slice = slice[32:]
+	// ... and make sure that we've at the very least the amount of bytes
+	// available in the buffer.
+	if size*32 > len(slice) {
+		return nil, fmt.Errorf("abi: cannot marshal in to go slice: insufficient size output %d require %d", len(output), offset+32+size*32)
+	}
+
+	// reslice to match the required size
+	slice = slice[:(size * 32)]
+	for i := 0; i < size; i++ {
+		var (
+			inter        interface{}             // interface type
+			returnOutput = slice[i*32 : i*32+32] // the return output
+		)
+
+		// set inter to the correct type (cast)
+		switch t.Type.T {
+		case IntTy, UintTy:
+			inter = common.BytesToBig(returnOutput)
+		case BoolTy:
+			inter = common.BytesToBig(returnOutput).Uint64() > 0
+		case AddressTy:
+			inter = common.BytesToAddress(returnOutput)
+		case HashTy:
+			inter = common.BytesToHash(returnOutput)
+		}
+		// append the item to our reflect slice
+		refSlice = reflect.Append(refSlice, reflect.ValueOf(inter))
+	}
+
+	// return the interface
+	return refSlice.Interface(), nil
+}
+
 // toGoType parses the input and casts it to the proper type defined by the ABI
 // argument in T.
 func toGoType(i int, t Argument, output []byte) (interface{}, error) {
-	index := i * 32
+	// we need to treat slices differently
+	if t.Type.IsSlice {
+		return toGoSlice(i, t, output)
+	}
 
+	index := i * 32
 	if index+32 > len(output) {
 		return nil, fmt.Errorf("abi: cannot marshal in to go type: length insufficient %d require %d", len(output), index+32)
 	}

accounts/abi/abi_test.go

@@ -49,7 +49,9 @@ const jsondata2 = `
 	{ "type" : "function", "name" : "foo", "const" : false, "inputs" : [ { "name" : "inputs", "type" : "uint32" } ] },
 	{ "type" : "function", "name" : "bar", "const" : false, "inputs" : [ { "name" : "inputs", "type" : "uint32" }, { "name" : "string", "type" : "uint16" } ] },
 	{ "type" : "function", "name" : "slice", "const" : false, "inputs" : [ { "name" : "inputs", "type" : "uint32[2]" } ] },
-	{ "type" : "function", "name" : "slice256", "const" : false, "inputs" : [ { "name" : "inputs", "type" : "uint256[2]" } ] }
+	{ "type" : "function", "name" : "slice256", "const" : false, "inputs" : [ { "name" : "inputs", "type" : "uint256[2]" } ] },
+	{ "type" : "function", "name" : "sliceAddress", "const" : false, "inputs" : [ { "name" : "inputs", "type" : "address[]" } ] },
+	{ "type" : "function", "name" : "sliceMultiAddress", "const" : false, "inputs" : [ { "name" : "a", "type" : "address[]" }, { "name" : "b", "type" : "address[]" } ] }
 ]`
 
 func TestType(t *testing.T) {
@@ -57,7 +59,7 @@ func TestType(t *testing.T) {
 	if err != nil {
 		t.Error(err)
 	}
-	if typ.Kind != reflect.Ptr {
+	if typ.Kind != reflect.Uint {
 		t.Error("expected uint32 to have kind Ptr")
 	}
 
@@ -65,10 +67,10 @@ func TestType(t *testing.T) {
 	if err != nil {
 		t.Error(err)
 	}
-	if typ.Kind != reflect.Slice {
+	if !typ.IsSlice {
-		t.Error("expected uint32[] to have type slice")
+		t.Error("expected uint32[] to be slice")
 	}
-	if typ.Type != ubig_ts {
+	if typ.Type != ubig_t {
 		t.Error("expcted uith32[] to have type uint64")
 	}
 
@@ -76,13 +78,13 @@ func TestType(t *testing.T) {
 	if err != nil {
 		t.Error(err)
 	}
-	if typ.Kind != reflect.Slice {
+	if !typ.IsSlice {
-		t.Error("expected uint32[2] to have kind slice")
+		t.Error("expected uint32[2] to be slice")
 	}
-	if typ.Type != ubig_ts {
+	if typ.Type != ubig_t {
 		t.Error("expcted uith32[2] to have type uint64")
 	}
-	if typ.Size != 2 {
+	if typ.SliceSize != 2 {
 		t.Error("expected uint32[2] to have a size of 2")
 	}
 }
@@ -147,10 +149,6 @@ func TestTestNumbers(t *testing.T) {
 		t.Errorf("expected send( ptr ) to throw, requires *big.Int instead of *int")
 	}
 
-	if _, err := abi.Pack("send", 1000); err != nil {
-		t.Error("expected send(1000) to cast to big")
-	}
-
 	if _, err := abi.Pack("test", uint32(1000)); err != nil {
 		t.Error(err)
 	}
@@ -202,17 +200,7 @@ func TestTestSlice(t *testing.T) {
 		t.FailNow()
 	}
 
-	addr := make([]byte, 20)
+	slice := make([]uint64, 2)
-	if _, err := abi.Pack("address", addr); err != nil {
-		t.Error(err)
-	}
-
-	addr = make([]byte, 21)
-	if _, err := abi.Pack("address", addr); err == nil {
-		t.Error("expected address of 21 width to throw")
-	}
-
-	slice := make([]byte, 2)
 	if _, err := abi.Pack("uint64[2]", slice); err != nil {
 		t.Error(err)
 	}
@@ -222,16 +210,18 @@ func TestTestSlice(t *testing.T) {
 	}
 }
 
-func TestTestAddress(t *testing.T) {
+func TestImplicitTypeCasts(t *testing.T) {
 	abi, err := JSON(strings.NewReader(jsondata2))
 	if err != nil {
 		t.Error(err)
 		t.FailNow()
 	}
 
-	addr := make([]byte, 20)
+	slice := make([]uint8, 2)
-	if _, err := abi.Pack("address", addr); err != nil {
+	_, err = abi.Pack("uint64[2]", slice)
-		t.Error(err)
+	expStr := "`uint64[2]` abi: cannot use type uint8 as type uint64"
+	if err.Error() != expStr {
+		t.Errorf("expected %v, got %v", expStr, err)
 	}
 }
 
@@ -310,44 +300,69 @@ func TestPackSlice(t *testing.T) {
 	}
 
 	sig := crypto.Keccak256([]byte("slice(uint32[2])"))[:4]
-	sig = append(sig, make([]byte, 64)...)
+	sig = append(sig, common.LeftPadBytes([]byte{32}, 32)...)
-	sig[35] = 1
+	sig = append(sig, common.LeftPadBytes([]byte{2}, 32)...)
-	sig[67] = 2
+	sig = append(sig, common.LeftPadBytes([]byte{1}, 32)...)
+	sig = append(sig, common.LeftPadBytes([]byte{2}, 32)...)
 
 	packed, err := abi.Pack("slice", []uint32{1, 2})
 	if err != nil {
 		t.Error(err)
-		t.FailNow()
+	}
+
+	if !bytes.Equal(packed, sig) {
+		t.Errorf("expected %x got %x", sig, packed)
+	}
+
+	var addrA, addrB = common.Address{1}, common.Address{2}
+	sig = abi.Methods["sliceAddress"].Id()
+	sig = append(sig, common.LeftPadBytes([]byte{32}, 32)...)
+	sig = append(sig, common.LeftPadBytes([]byte{2}, 32)...)
+	sig = append(sig, common.LeftPadBytes(addrA[:], 32)...)
+	sig = append(sig, common.LeftPadBytes(addrB[:], 32)...)
+
+	packed, err = abi.Pack("sliceAddress", []common.Address{addrA, addrB})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(packed, sig) {
+		t.Errorf("expected %x got %x", sig, packed)
+	}
+
+	var addrC, addrD = common.Address{3}, common.Address{4}
+	sig = abi.Methods["sliceMultiAddress"].Id()
+	sig = append(sig, common.LeftPadBytes([]byte{64}, 32)...)
+	sig = append(sig, common.LeftPadBytes([]byte{160}, 32)...)
+	sig = append(sig, common.LeftPadBytes([]byte{2}, 32)...)
+	sig = append(sig, common.LeftPadBytes(addrA[:], 32)...)
+	sig = append(sig, common.LeftPadBytes(addrB[:], 32)...)
+	sig = append(sig, common.LeftPadBytes([]byte{2}, 32)...)
+	sig = append(sig, common.LeftPadBytes(addrC[:], 32)...)
+	sig = append(sig, common.LeftPadBytes(addrD[:], 32)...)
+
+	packed, err = abi.Pack("sliceMultiAddress", []common.Address{addrA, addrB}, []common.Address{addrC, addrD})
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !bytes.Equal(packed, sig) {
+		t.Errorf("expected %x got %x", sig, packed)
+	}
+
+	sig = crypto.Keccak256([]byte("slice256(uint256[2])"))[:4]
+	sig = append(sig, common.LeftPadBytes([]byte{32}, 32)...)
+	sig = append(sig, common.LeftPadBytes([]byte{2}, 32)...)
+	sig = append(sig, common.LeftPadBytes([]byte{1}, 32)...)
+	sig = append(sig, common.LeftPadBytes([]byte{2}, 32)...)
+
+	packed, err = abi.Pack("slice256", []*big.Int{big.NewInt(1), big.NewInt(2)})
+	if err != nil {
+		t.Error(err)
 	}
 
 	if !bytes.Equal(packed, sig) {
 		t.Errorf("expected %x got %x", sig, packed)
 	}
 }
-
-func TestPackSliceBig(t *testing.T) {
-	abi, err := JSON(strings.NewReader(jsondata2))
-	if err != nil {
-		t.Error(err)
-		t.FailNow()
-	}
-
-	sig := crypto.Keccak256([]byte("slice256(uint256[2])"))[:4]
-	sig = append(sig, make([]byte, 64)...)
-	sig[35] = 1
-	sig[67] = 2
-
-	packed, err := abi.Pack("slice256", []*big.Int{big.NewInt(1), big.NewInt(2)})
-	if err != nil {
-		t.Error(err)
-		t.FailNow()
-	}
-
-	if !bytes.Equal(packed, sig) {
-		t.Errorf("expected %x got %x", sig, packed)
-	}
-}
-
 func ExampleJSON() {
 	const definition = `[{"constant":true,"inputs":[{"name":"","type":"address"}],"name":"isBar","outputs":[{"name":"","type":"bool"}],"type":"function"}]`
 
@@ -370,7 +385,7 @@ func TestInputVariableInputLength(t *testing.T) {
 	{ "type" : "function", "name" : "strOne", "const" : true, "inputs" : [ { "name" : "str", "type" : "string" } ] },
 	{ "type" : "function", "name" : "bytesOne", "const" : true, "inputs" : [ { "name" : "str", "type" : "bytes" } ] },
 	{ "type" : "function", "name" : "strTwo", "const" : true, "inputs" : [ { "name" : "str", "type" : "string" }, { "name" : "str1", "type" : "string" } ] }
-]`
+	]`
 
 	abi, err := JSON(strings.NewReader(definition))
 	if err != nil {
@@ -493,35 +508,6 @@ func TestInputVariableInputLength(t *testing.T) {
 	}
 }
 
-func TestBytes(t *testing.T) {
-	const definition = `[
-	{ "type" : "function", "name" : "balance", "const" : true, "inputs" : [ { "name" : "address", "type" : "bytes20" } ] },
-	{ "type" : "function", "name" : "send", "const" : false, "inputs" : [ { "name" : "amount", "type" : "uint256" } ] }
-]`
-
-	abi, err := JSON(strings.NewReader(definition))
-	if err != nil {
-		t.Fatal(err)
-	}
-	ok := make([]byte, 20)
-	_, err = abi.Pack("balance", ok)
-	if err != nil {
-		t.Error(err)
-	}
-
-	toosmall := make([]byte, 19)
-	_, err = abi.Pack("balance", toosmall)
-	if err != nil {
-		t.Error(err)
-	}
-
-	toobig := make([]byte, 21)
-	_, err = abi.Pack("balance", toobig)
-	if err == nil {
-		t.Error("expected error")
-	}
-}
-
 func TestDefaultFunctionParsing(t *testing.T) {
 	const definition = `[{ "name" : "balance" }]`
 
@@ -713,12 +699,15 @@ func TestUnmarshal(t *testing.T) {
 	{ "name" : "bytes", "const" : false, "outputs": [ { "type": "bytes" } ] },
 	{ "name" : "fixed", "const" : false, "outputs": [ { "type": "bytes32" } ] },
 	{ "name" : "multi", "const" : false, "outputs": [ { "type": "bytes" }, { "type": "bytes" } ] },
+	{ "name" : "addressSliceSingle", "const" : false, "outputs": [ { "type": "address[]" } ] },
+	{ "name" : "addressSliceDouble", "const" : false, "outputs": [ { "name": "a", "type": "address[]" }, { "name": "b", "type": "address[]" } ] },
 	{ "name" : "mixedBytes", "const" : true, "outputs": [ { "name": "a", "type": "bytes" }, { "name": "b", "type": "bytes32" } ] }]`
 
 	abi, err := JSON(strings.NewReader(definition))
 	if err != nil {
 		t.Fatal(err)
 	}
+	buff := new(bytes.Buffer)
 
 	// marshal int
 	var Int *big.Int
@@ -743,7 +732,6 @@ func TestUnmarshal(t *testing.T) {
 	}
 
 	// marshal dynamic bytes max length 32
-	buff := new(bytes.Buffer)
 	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000020"))
 	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000020"))
 	bytesOut := common.RightPadBytes([]byte("hello"), 32)
@@ -862,4 +850,71 @@ func TestUnmarshal(t *testing.T) {
 	if !bytes.Equal(fixed, out[1].([]byte)) {
 		t.Errorf("expected %x, got %x", fixed, out[1])
 	}
+
+	// marshal address slice
+	buff.Reset()
+	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000020")) // offset
+	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001")) // size
+	buff.Write(common.Hex2Bytes("0000000000000000000000000100000000000000000000000000000000000000"))
+
+	var outAddr []common.Address
+	err = abi.Unpack(&outAddr, "addressSliceSingle", buff.Bytes())
+	if err != nil {
+		t.Fatal("didn't expect error:", err)
+	}
+
+	if len(outAddr) != 1 {
+		t.Fatal("expected 1 item, got", len(outAddr))
+	}
+
+	if outAddr[0] != (common.Address{1}) {
+		t.Errorf("expected %x, got %x", common.Address{1}, outAddr[0])
+	}
+
+	// marshal multiple address slice
+	buff.Reset()
+	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000040")) // offset
+	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000080")) // offset
+	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000001")) // size
+	buff.Write(common.Hex2Bytes("0000000000000000000000000100000000000000000000000000000000000000"))
+	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000002")) // size
+	buff.Write(common.Hex2Bytes("0000000000000000000000000200000000000000000000000000000000000000"))
+	buff.Write(common.Hex2Bytes("0000000000000000000000000300000000000000000000000000000000000000"))
+
+	var outAddrStruct struct {
+		A []common.Address
+		B []common.Address
+	}
+	err = abi.Unpack(&outAddrStruct, "addressSliceDouble", buff.Bytes())
+	if err != nil {
+		t.Fatal("didn't expect error:", err)
+	}
+
+	if len(outAddrStruct.A) != 1 {
+		t.Fatal("expected 1 item, got", len(outAddrStruct.A))
+	}
+
+	if outAddrStruct.A[0] != (common.Address{1}) {
+		t.Errorf("expected %x, got %x", common.Address{1}, outAddrStruct.A[0])
+	}
+
+	if len(outAddrStruct.B) != 2 {
+		t.Fatal("expected 1 item, got", len(outAddrStruct.B))
+	}
+
+	if outAddrStruct.B[0] != (common.Address{2}) {
+		t.Errorf("expected %x, got %x", common.Address{2}, outAddrStruct.B[0])
+	}
+	if outAddrStruct.B[1] != (common.Address{3}) {
+		t.Errorf("expected %x, got %x", common.Address{3}, outAddrStruct.B[1])
+	}
+
+	// marshal invalid address slice
+	buff.Reset()
+	buff.Write(common.Hex2Bytes("0000000000000000000000000000000000000000000000000000000000000100"))
+
+	err = abi.Unpack(&outAddr, "addressSliceSingle", buff.Bytes())
+	if err == nil {
+		t.Fatal("expected error:", err)
+	}
 }

accounts/abi/numbers.go

@@ -117,8 +117,6 @@ func packNum(value reflect.Value, to byte) []byte {
 // checks whether the given reflect value is signed. This also works for slices with a number type
 func isSigned(v reflect.Value) bool {
 	switch v.Type() {
-	case ubig_ts, big_ts, big_t, ubig_t:
-		return true
 	case int_ts, int8_ts, int16_ts, int32_ts, int64_ts, int_t, int8_t, int16_t, int32_t, int64_t:
 		return true
 	}

accounts/abi/numbers_test.go

@@ -81,8 +81,4 @@ func TestSigned(t *testing.T) {
 	if !isSigned(reflect.ValueOf(int(10))) {
 		t.Error()
 	}
-
-	if !isSigned(reflect.ValueOf(big.NewInt(10))) {
-		t.Error()
-	}
 }

accounts/abi/type.go

@@ -40,6 +40,9 @@ const (
 
 // Type is the reflection of the supported argument type
 type Type struct {
+	IsSlice   bool
+	SliceSize int
+
 	Kind       reflect.Kind
 	Type       reflect.Type
 	Size       int
@@ -47,6 +50,11 @@ type Type struct {
 	stringKind string // holds the unparsed string for deriving signatures
 }
 
+var (
+	fullTypeRegex = regexp.MustCompile("([a-zA-Z0-9]+)(\\[([0-9]*)?\\])?")
+	typeRegex     = regexp.MustCompile("([a-zA-Z]+)([0-9]*)?")
+)
+
 // NewType returns a fully parsed Type given by the input string or an error if it  can't be parsed.
 //
 // Strings can be in the format of:
@@ -61,98 +69,87 @@ type Type struct {
 //      address    int256    uint256    real[2]
 func NewType(t string) (typ Type, err error) {
 	// 1. full string 2. type 3. (opt.) is slice 4. (opt.) size
-	freg, err := regexp.Compile("([a-zA-Z0-9]+)(\\[([0-9]*)?\\])?")
+	// parse the full representation of the abi-type definition; including:
-	if err != nil {
+	// * full string
-		return Type{}, err
+	// * type
-	}
+	// 	* is slice
-	res := freg.FindAllStringSubmatch(t, -1)[0]
+	//	* slice size
-	var (
+	res := fullTypeRegex.FindAllStringSubmatch(t, -1)[0]
-		isslice bool
+
-		size    int
+	// check if type is slice and parse type.
-	)
 	switch {
 	case res[3] != "":
 		// err is ignored. Already checked for number through the regexp
-		size, _ = strconv.Atoi(res[3])
+		typ.SliceSize, _ = strconv.Atoi(res[3])
-		isslice = true
+		typ.IsSlice = true
 	case res[2] != "":
-		isslice = true
+		typ.IsSlice, typ.SliceSize = true, -1
-		size = -1
 	case res[0] == "":
-		return Type{}, fmt.Errorf("type parse error for `%s`", t)
+		return Type{}, fmt.Errorf("abi: type parse error: %s", t)
 	}
 
-	treg, err := regexp.Compile("([a-zA-Z]+)([0-9]*)?")
+	// parse the type and size of the abi-type.
-	if err != nil {
+	parsedType := typeRegex.FindAllStringSubmatch(res[1], -1)[0]
-		return Type{}, err
+	// varSize is the size of the variable
+	var varSize int
+	if len(parsedType[2]) > 0 {
+		var err error
+		varSize, err = strconv.Atoi(parsedType[2])
+		if err != nil {
+			return Type{}, fmt.Errorf("abi: error parsing variable size: %v", err)
+		}
 	}
-
+	// varType is the parsed abi type
-	parsedType := treg.FindAllStringSubmatch(res[1], -1)[0]
+	varType := parsedType[1]
-	vsize, _ := strconv.Atoi(parsedType[2])
+	// substitute canonical integer
-	vtype := parsedType[1]
+	if varSize == 0 && (varType == "int" || varType == "uint") {
-	// substitute canonical representation
+		varSize = 256
-	if vsize == 0 && (vtype == "int" || vtype == "uint") {
-		vsize = 256
 		t += "256"
 	}
 
-	if isslice {
+	switch varType {
-		typ.Kind = reflect.Slice
+	case "int":
-		typ.Size = size
+		typ.Kind = reflect.Int
-		switch vtype {
+		typ.Type = big_t
-		case "int":
+		typ.Size = varSize
-			typ.Type = big_ts
+		typ.T = IntTy
-		case "uint":
+	case "uint":
-			typ.Type = ubig_ts
+		typ.Kind = reflect.Uint
-		default:
+		typ.Type = ubig_t
-			return Type{}, fmt.Errorf("unsupported arg slice type: %s", t)
+		typ.Size = varSize
-		}
+		typ.T = UintTy
-	} else {
+	case "bool":
-		switch vtype {
+		typ.Kind = reflect.Bool
-		case "int":
+		typ.T = BoolTy
-			typ.Kind = reflect.Ptr
+	case "real": // TODO
-			typ.Type = big_t
+		typ.Kind = reflect.Invalid
-			typ.Size = 256
+	case "address":
-			typ.T = IntTy
+		typ.Type = address_t
-		case "uint":
+		typ.Size = 20
-			typ.Kind = reflect.Ptr
+		typ.T = AddressTy
-			typ.Type = ubig_t
+	case "string":
-			typ.Size = 256
+		typ.Kind = reflect.String
-			typ.T = UintTy
+		typ.Size = -1
-		case "bool":
+		typ.T = StringTy
-			typ.Kind = reflect.Bool
+		if varSize > 0 {
-			typ.T = BoolTy
-		case "real": // TODO
-			typ.Kind = reflect.Invalid
-		case "address":
-			typ.Kind = reflect.Slice
-			typ.Type = address_t
-			typ.Size = 20
-			typ.T = AddressTy
-		case "string":
-			typ.Kind = reflect.String
-			typ.Size = -1
-			typ.T = StringTy
-			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
-			typ.Size = vsize
-			if vsize == 0 {
-				typ.T = BytesTy
-			} else {
-				typ.T = FixedBytesTy
-			}
-		default:
-			return Type{}, fmt.Errorf("unsupported arg type: %s", t)
 		}
+	case "hash":
+		typ.Kind = reflect.Array
+		typ.Size = 32
+		typ.Type = hash_t
+		typ.T = HashTy
+	case "bytes":
+		typ.Kind = reflect.Array
+		typ.Type = byte_ts
+		typ.Size = varSize
+		if varSize == 0 {
+			typ.T = BytesTy
+		} else {
+			typ.T = FixedBytesTy
+		}
+	default:
+		return Type{}, fmt.Errorf("unsupported arg type: %s", t)
 	}
 	typ.stringKind = t
 
@@ -180,14 +177,26 @@ func (t Type) pack(v interface{}) ([]byte, error) {
 	value := reflect.ValueOf(v)
 	switch kind := value.Kind(); kind {
 	case reflect.Uint, reflect.Uint8, reflect.Uint16, reflect.Uint32, reflect.Uint64:
+		// check input is unsigned
 		if t.Type != ubig_t {
-			return nil, fmt.Errorf("type mismatch: %s for %T", t.Type, v)
+			return nil, fmt.Errorf("abi: type mismatch: %s for %T", t.Type, v)
 		}
+
+		// no implicit type casting
+		if int(value.Type().Size()*8) != t.Size {
+			return nil, fmt.Errorf("abi: cannot use type %T as type uint%d", v, t.Size)
+		}
+
 		return packNum(value, t.T), nil
 	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32, reflect.Int64:
 		if t.Type != ubig_t {
 			return nil, fmt.Errorf("type mismatch: %s for %T", t.Type, v)
 		}
+
+		// no implicit type casting
+		if int(value.Type().Size()*8) != t.Size {
+			return nil, fmt.Errorf("abi: cannot use type %T as type uint%d", v, t.Size)
+		}
 		return packNum(value, t.T), nil
 	case reflect.Ptr:
 		// If the value is a ptr do a assign check (only used by
@@ -203,30 +212,29 @@ func (t Type) pack(v interface{}) ([]byte, error) {
 
 		return packBytesSlice([]byte(value.String()), value.Len()), nil
 	case reflect.Slice:
-		// if the param is a bytes type, pack the slice up as a string
+		// Byte slice is a special case, it gets treated as a single value
 		if t.T == BytesTy {
 			return packBytesSlice(value.Bytes(), value.Len()), nil
 		}
 
-		if t.Size > -1 && value.Len() > t.Size {
+		if t.SliceSize > -1 && value.Len() > t.SliceSize {
 			return nil, fmt.Errorf("%v out of bound. %d for %d", value.Kind(), value.Len(), t.Size)
 		}
 
-		// Address is a special slice. The slice acts as one rather than a list of elements.
-		if t.T == AddressTy {
-			return common.LeftPadBytes(v.([]byte), 32), nil
-		}
-
 		// Signed / Unsigned check
-		if (t.T != IntTy && isSigned(value)) || (t.T == UintTy && isSigned(value)) {
+		if value.Type() == big_t && (t.T != IntTy && isSigned(value)) || (t.T == UintTy && isSigned(value)) {
 			return nil, fmt.Errorf("slice of incompatible types.")
 		}
 
 		var packed []byte
 		for i := 0; i < value.Len(); i++ {
-			packed = append(packed, packNum(value.Index(i), t.T)...)
+			val, err := t.pack(value.Index(i).Interface())
+			if err != nil {
+				return nil, err
+			}
+			packed = append(packed, val...)
 		}
-		return packed, nil
+		return packBytesSlice(packed, value.Len()), nil
 	case reflect.Bool:
 		if value.Bool() {
 			return common.LeftPadBytes(common.Big1.Bytes(), 32), nil