// 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"
"reflect"
"strings"
)
// 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
Indexed bool // indexed is only used by events
}
type Arguments []Argument
// UnmarshalJSON implements json.Unmarshaler interface
func (argument *Argument) UnmarshalJSON(data []byte) error {
var extarg struct {
Name string
Type string
Indexed bool
}
err := json.Unmarshal(data, &extarg)
if err != nil {
return fmt.Errorf("argument json err: %v", err)
}
argument.Type, err = NewType(extarg.Type)
if err != nil {
return err
}
argument.Name = extarg.Name
argument.Indexed = extarg.Indexed
return nil
}
// LengthNonIndexed returns the number of arguments when not counting 'indexed' ones. Only events
// can ever have 'indexed' arguments, it should always be false on arguments for method input/output
func (arguments Arguments) LengthNonIndexed() int {
out := 0
for _, arg := range arguments {
if !arg.Indexed {
out++
}
}
return out
}
// isTuple returns true for non-atomic constructs, like (uint,uint) or uint[]
func (arguments Arguments) isTuple() bool {
return len(arguments) > 1
}
// Unpack performs the operation hexdata -> Go format
func (arguments Arguments) Unpack(v interface{}, data []byte) error {
if arguments.isTuple() {
return arguments.unpackTuple(v, data)
}
return arguments.unpackAtomic(v, data)
}
func (arguments Arguments) unpackTuple(v interface{}, output []byte) error {
// make sure the passed value is arguments pointer
valueOf := reflect.ValueOf(v)
if reflect.Ptr != valueOf.Kind() {
return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
}
var (
value = valueOf.Elem()
typ = value.Type()
kind = value.Kind()
)
if err := requireUnpackKind(value, typ, kind, arguments); err != nil {
return err
}
// If the output interface is a struct, make sure names don't collide
if kind == reflect.Struct {
exists := make(map[string]bool)
for _, arg := range arguments {
field := capitalise(arg.Name)
if field == "" {
return fmt.Errorf("abi: purely underscored output cannot unpack to struct")
}
if exists[field] {
return fmt.Errorf("abi: multiple outputs mapping to the same struct field '%s'", field)
}
exists[field] = true
}
}
// `i` counts the nonindexed arguments.
// `j` counts the number of complex types.
// both `i` and `j` are used to to correctly compute `data` offset.
i, j := -1, 0
for _, arg := range arguments {
if arg.Indexed {
// can't read, continue
continue
}
i++
marshalledValue, err := toGoType((i+j)*32, arg.Type, output)
if err != nil {
return err
}
if arg.Type.T == ArrayTy {
// combined index ('i' + 'j') need to be adjusted only by size of array, thus
// we need to decrement 'j' because 'i' was incremented
j += arg.Type.Size - 1
}
reflectValue := reflect.ValueOf(marshalledValue)
switch kind {
case reflect.Struct:
name := capitalise(arg.Name)
for j := 0; j < typ.NumField(); j++ {
// TODO read tags: `abi:"fieldName"`
if typ.Field(j).Name == name {
if err := set(value.Field(j), reflectValue, arg); err != nil {
return err
}
}
}
case reflect.Slice, reflect.Array:
if value.Len() < i {
return fmt.Errorf("abi: insufficient number of arguments for unpack, want %d, got %d", len(arguments), value.Len())
}
v := value.Index(i)
if err := requireAssignable(v, reflectValue); err != nil {
return err
}
if err := set(v.Elem(), reflectValue, arg); err != nil {
return err
}
default:
return fmt.Errorf("abi:[2] cannot unmarshal tuple in to %v", typ)
}
}
return nil
}
// unpackAtomic unpacks ( hexdata -> go ) a single value
func (arguments Arguments) unpackAtomic(v interface{}, output []byte) error {
// make sure the passed value is arguments pointer
valueOf := reflect.ValueOf(v)
if reflect.Ptr != valueOf.Kind() {
return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
}
arg := arguments[0]
if arg.Indexed {
return fmt.Errorf("abi: attempting to unpack indexed variable into element.")
}
value := valueOf.Elem()
marshalledValue, err := toGoType(0, arg.Type, output)
if err != nil {
return err
}
return set(value, reflect.ValueOf(marshalledValue), arg)
}
// Unpack performs the operation Go format -> Hexdata
func (arguments Arguments) Pack(args ...interface{}) ([]byte, error) {
// Make sure arguments match up and pack them
abiArgs := arguments
if len(args) != len(abiArgs) {
return nil, fmt.Errorf("argument count mismatch: %d for %d", len(args), len(abiArgs))
}
// variable input is the output appended at the end of packed
// output. This is used for strings and bytes types input.
var variableInput []byte
// input offset is the bytes offset for packed output
inputOffset := 0
for _, abiArg := range abiArgs {
if abiArg.Type.T == ArrayTy {
inputOffset += (32 * abiArg.Type.Size)
} else {
inputOffset += 32
}
}
var ret []byte
for i, a := range args {
input := abiArgs[i]
// pack the input
packed, err := input.Type.pack(reflect.ValueOf(a))
if err != nil {
return nil, err
}
// check for a slice type (string, bytes, slice)
if input.Type.requiresLengthPrefix() {
// calculate the offset
offset := inputOffset + len(variableInput)
// set the offset
ret = append(ret, packNum(reflect.ValueOf(offset))...)
// 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
}
// capitalise makes the first character of a string upper case, also removing any
// prefixing underscores from the variable names.
func capitalise(input string) string {
for len(input) > 0 && input[0] == '_' {
input = input[1:]
}
if len(input) == 0 {
return ""
}
return strings.ToUpper(input[:1]) + input[1:]
}
