2015-11-20 12:45:37 +00:00
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// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package abi
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import (
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"fmt"
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2016-04-07 09:39:22 +00:00
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"reflect"
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2015-11-20 12:45:37 +00:00
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"strings"
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"github.com/ethereum/go-ethereum/crypto"
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)
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2017-11-10 01:48:51 +00:00
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// Method represents a callable given a `Name` and whether the method is a constant.
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2015-11-20 12:45:37 +00:00
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// If the method is `Const` no transaction needs to be created for this
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// particular Method call. It can easily be simulated using a local VM.
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// For example a `Balance()` method only needs to retrieve something
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// from the storage and therefor requires no Tx to be send to the
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// network. A method such as `Transact` does require a Tx and thus will
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// be flagged `true`.
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// Input specifies the required input parameters for this gives method.
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type Method struct {
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Name string
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Const bool
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Inputs []Argument
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Outputs []Argument
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}
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2017-06-27 08:05:33 +00:00
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func (method Method) pack(args ...interface{}) ([]byte, error) {
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// Make sure arguments match up and pack them
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if len(args) != len(method.Inputs) {
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return nil, fmt.Errorf("argument count mismatch: %d for %d", len(args), len(method.Inputs))
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}
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// variable input is the output appended at the end of packed
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// output. This is used for strings and bytes types input.
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var variableInput []byte
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2017-10-12 14:58:53 +00:00
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// input offset is the bytes offset for packed output
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inputOffset := 0
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for _, input := range method.Inputs {
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if input.Type.T == ArrayTy {
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inputOffset += (32 * input.Type.Size)
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} else {
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inputOffset += 32
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}
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}
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2016-04-07 09:39:22 +00:00
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var ret []byte
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for i, a := range args {
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input := method.Inputs[i]
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// pack the input
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packed, err := input.Type.pack(reflect.ValueOf(a))
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if err != nil {
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return nil, fmt.Errorf("`%s` %v", method.Name, err)
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}
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// check for a slice type (string, bytes, slice)
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if input.Type.requiresLengthPrefix() {
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// calculate the offset
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offset := inputOffset + len(variableInput)
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// set the offset
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ret = append(ret, packNum(reflect.ValueOf(offset))...)
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// Append the packed output to the variable input. The variable input
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// will be appended at the end of the input.
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variableInput = append(variableInput, packed...)
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} else {
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// append the packed value to the input
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ret = append(ret, packed...)
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}
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}
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// append the variable input at the end of the packed input
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ret = append(ret, variableInput...)
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return ret, nil
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}
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2017-10-17 11:07:08 +00:00
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// unpacks a method return tuple into a struct of corresponding go types
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//
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// Unpacking can be done into a struct or a slice/array.
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func (method Method) tupleUnpack(v interface{}, outputSlice []byte) error {
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// make sure the passed value is a pointer
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valueOf := reflect.ValueOf(v)
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if reflect.Ptr != valueOf.Kind() {
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return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
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}
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var (
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value = valueOf.Elem()
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typ = value.Type()
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kind = value.Kind()
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)
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if err := requireUnpackKind(value, typ, kind, method.Outputs, false); err != nil {
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return err
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}
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j := 0
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for i, output := range method.Outputs {
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marshalledValue, err := toGoType((i+j)*32, ouptut.Type, outputSlice)
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if err != nil {
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return err
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}
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if output.Type.T == ArrayTy {
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2017-12-20 14:09:23 +00:00
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// combined index ('i' + 'j') need to be adjusted only by size of array, thus
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// we need to decrement 'j' because 'i' was incremented
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j += output.Type.Size - 1
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}
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reflectValue := reflect.ValueOf(marshalledValue)
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2017-11-10 01:30:26 +00:00
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switch kind {
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case reflect.Struct:
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for j := 0; j < typ.NumField(); j++ {
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field := typ.Field(j)
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// TODO read tags: `abi:"fieldName"`
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if field.Name == strings.ToUpper(output.Name[:1])+output.Name[1:] {
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if err := set(value.Field(j), reflectValue, output); err != nil {
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return err
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}
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}
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}
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case reflect.Slice, reflect.Array:
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v := value.Index(i)
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if err := requireAssignable(v, reflectValue); err != nil {
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return err
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}
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if err := set(v.Elem(), reflectValue, output); err != nil {
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return err
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}
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}
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}
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return nil
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}
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func (method Method) isTupleReturn() bool { return len(method.Outputs) > 1 }
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func (method Method) singleUnpack(v interface{}, output []byte) error {
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// make sure the passed value is a pointer
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valueOf := reflect.ValueOf(v)
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if reflect.Ptr != valueOf.Kind() {
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return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
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}
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value := valueOf.Elem()
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marshalledValue, err := toGoType(0, method.Outputs[0].Type, output)
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if err != nil {
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return err
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}
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return set(value, reflect.ValueOf(marshalledValue), method.Outputs[0])
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}
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2015-11-20 12:45:37 +00:00
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// Sig returns the methods string signature according to the ABI spec.
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//
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// Example
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//
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// function foo(uint32 a, int b) = "foo(uint32,int256)"
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//
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// Please note that "int" is substitute for its canonical representation "int256"
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func (method Method) Sig() string {
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types := make([]string, len(method.Inputs))
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i := 0
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for _, input := range method.Inputs {
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types[i] = input.Type.String()
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i++
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}
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return fmt.Sprintf("%v(%v)", method.Name, strings.Join(types, ","))
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}
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func (method Method) String() string {
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inputs := make([]string, len(method.Inputs))
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for i, input := range method.Inputs {
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inputs[i] = fmt.Sprintf("%v %v", input.Name, input.Type)
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}
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outputs := make([]string, len(method.Outputs))
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for i, output := range method.Outputs {
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2015-11-20 12:45:37 +00:00
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if len(output.Name) > 0 {
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outputs[i] = fmt.Sprintf("%v ", output.Name)
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}
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outputs[i] += output.Type.String()
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}
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2016-03-16 09:19:25 +00:00
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constant := ""
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if method.Const {
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constant = "constant "
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}
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return fmt.Sprintf("function %v(%v) %sreturns(%v)", method.Name, strings.Join(inputs, ", "), constant, strings.Join(outputs, ", "))
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}
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2017-11-10 01:48:51 +00:00
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func (method Method) Id() []byte {
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return crypto.Keccak256([]byte(method.Sig()))[:4]
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}
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