accouns/abi: refactored ABI package

Refactored the abi package parsing and type handling. Relying mostly on
package reflect as opposed to most of our own type reflection. Our own
type reflection is still used however for cases such as Bytes and
FixedBytes (abi: bytes•).

This also inclused several fixes for slice handling of arbitrary and
fixed size for all supported types.

This also further removes implicit type casting such as assigning,
for example `[2]T{} = []T{1}` will fail, however `[2]T{} == []T{1, 2}`
(notice assigning *slice* to fixed size *array*). Assigning arrays to
slices will always succeed if they are of the same element type.

Incidentally also fixes #2379

1 files changed, 10 insertions, 47 deletions

diff --git a/accounts/abi/abi.go b/accounts/abi/abi.go
index 9ef7c0f0d..82ea4a0d5 100644
--- a/accounts/abi/abi.go
+++ b/accounts/abi/abi.go
@@ -48,42 +48,6 @@ func JSON(reader io.Reader) (ABI, error) {
 	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(method Method, args ...interface{}) ([]byte, error) {
-	// variable input is the output appended at the end of packed
-	// output. This is used for strings and bytes types input.
-	var variableInput []byte
-
-	var ret []byte
-	for i, a := range args {
-		input := method.Inputs[i]
-		// pack the input
-		packed, err := input.Type.pack(a)
-		if err != nil {
-			return nil, fmt.Errorf("`%s` %v", method.Name, err)
-		}
-
-		// check for a slice type (string, bytes, slice)
-		if input.Type.T == StringTy || input.Type.T == BytesTy || input.Type.IsSlice {
-			// calculate the offset
-			offset := len(method.Inputs)*32 + len(variableInput)
-			// set the offset
-			ret = append(ret, packNum(reflect.ValueOf(offset), UintTy)...)
-			// Append the packed output to the variable input. The variable input
-			// will be appended at the end of the input.
-			variableInput = append(variableInput, packed...)
-		} else {
-			// append the packed value to the input
-			ret = append(ret, packed...)
-		}
-	}
-	// append the variable input at the end of the packed input
-	ret = append(ret, variableInput...)
-
-	return ret, nil
-}
-
 // Pack the given method name to conform the ABI. Method call's data
 // will consist of method_id, args0, arg1, ... argN. Method id consists
 // of 4 bytes and arguments are all 32 bytes.
@@ -102,11 +66,7 @@ func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
 		}
 		method = m
 	}
-	// Make sure arguments match up and pack them
-	if len(args) != len(method.Inputs) {
-		return nil, fmt.Errorf("argument count mismatch: %d for %d", len(args), len(method.Inputs))
-	}
-	arguments, err := abi.pack(method, args...)
+	arguments, err := method.pack(method, args...)
 	if err != nil {
 		return nil, err
 	}
@@ -126,18 +86,21 @@ func toGoSlice(i int, t Argument, output []byte) (interface{}, error) {
 	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)
 	}
+	elem := t.Type.Elem
 
 	// first we need to create a slice of the type
 	var refSlice reflect.Value
-	switch t.Type.T {
+	switch elem.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))
+	case FixedBytesTy:
+		refSlice = reflect.ValueOf([]byte(nil))
 	default: // no other types are supported
-		return nil, fmt.Errorf("abi: unsupported slice type %v", t.Type.T)
+		return nil, fmt.Errorf("abi: unsupported slice type %v", elem.T)
 	}
 	// get the offset which determines the start of this array ...
 	offset := int(common.BytesToBig(output[index : index+32]).Uint64())
@@ -164,7 +127,7 @@ func toGoSlice(i int, t Argument, output []byte) (interface{}, error) {
 		)
 
 		// set inter to the correct type (cast)
-		switch t.Type.T {
+		switch elem.T {
 		case IntTy, UintTy:
 			inter = common.BytesToBig(returnOutput)
 		case BoolTy:
@@ -186,7 +149,7 @@ func toGoSlice(i int, t Argument, output []byte) (interface{}, error) {
 // argument in T.
 func toGoType(i int, t Argument, output []byte) (interface{}, error) {
 	// we need to treat slices differently
-	if t.Type.IsSlice {
+	if (t.Type.IsSlice || t.Type.IsArray) && t.Type.T != BytesTy && t.Type.T != StringTy && t.Type.T != FixedBytesTy {
 		return toGoSlice(i, t, output)
 	}
 
@@ -328,8 +291,8 @@ func set(dst, src reflect.Value, output Argument) error {
 			return fmt.Errorf("abi: cannot unmarshal %v in to array of elem %v", src.Type(), dstType.Elem())
 		}
 
-		if dst.Len() < output.Type.Size {
-			return fmt.Errorf("abi: cannot unmarshal src (len=%d) in to dst (len=%d)", output.Type.Size, dst.Len())
+		if dst.Len() < output.Type.SliceSize {
+			return fmt.Errorf("abi: cannot unmarshal src (len=%d) in to dst (len=%d)", output.Type.SliceSize, dst.Len())
 		}
 		reflect.Copy(dst, src)
 	default: