path: root/accounts/abi/argument.go

// 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

type ArgumentMarshaling struct {
    Name       string
    Type       string
    Components []ArgumentMarshaling
    Indexed    bool
}

// UnmarshalJSON implements json.Unmarshaler interface
func (argument *Argument) UnmarshalJSON(data []byte) error {
    var arg ArgumentMarshaling
    err := json.Unmarshal(data, &arg)
    if err != nil {
        return fmt.Errorf("argument json err: %v", err)
    }

    argument.Type, err = NewType(arg.Type, arg.Components)
    if err != nil {
        return err
    }
    argument.Name = arg.Name
    argument.Indexed = arg.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
}

// NonIndexed returns the arguments with indexed arguments filtered out
func (arguments Arguments) NonIndexed() Arguments {
    var ret []Argument
    for _, arg := range arguments {
        if !arg.Indexed {
            ret = append(ret, arg)
        }
    }
    return ret
}

// 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 {
    // make sure the passed value is arguments pointer
    if reflect.Ptr != reflect.ValueOf(v).Kind() {
        return fmt.Errorf("abi: Unpack(non-pointer %T)", v)
    }
    marshalledValues, err := arguments.UnpackValues(data)
    if err != nil {
        return err
    }
    if arguments.isTuple() {
        return arguments.unpackTuple(v, marshalledValues)
    }
    return arguments.unpackAtomic(v, marshalledValues[0])
}

// UnpackIntoMap performs the operation hexdata -> mapping of argument name to argument value
func (arguments Arguments) UnpackIntoMap(v map[string]interface{}, data []byte) error {
    marshalledValues, err := arguments.UnpackValues(data)
    if err != nil {
        return err
    }

    return arguments.unpackIntoMap(v, marshalledValues)
}

// unpack sets the unmarshalled value to go format.
// Note the dst here must be settable.
func unpack(t *Type, dst interface{}, src interface{}) error {
    var (
        dstVal = reflect.ValueOf(dst).Elem()
        srcVal = reflect.ValueOf(src)
    )

    if t.T != TupleTy && !((t.T == SliceTy || t.T == ArrayTy) && t.Elem.T == TupleTy) {
        return set(dstVal, srcVal)
    }

    switch t.T {
    case TupleTy:
        if dstVal.Kind() != reflect.Struct {
            return fmt.Errorf("abi: invalid dst value for unpack, want struct, got %s", dstVal.Kind())
        }
        fieldmap, err := mapArgNamesToStructFields(t.TupleRawNames, dstVal)
        if err != nil {
            return err
        }
        for i, elem := range t.TupleElems {
            fname := fieldmap[t.TupleRawNames[i]]
            field := dstVal.FieldByName(fname)
            if !field.IsValid() {
                return fmt.Errorf("abi: field %s can't found in the given value", t.TupleRawNames[i])
            }
            if err := unpack(elem, field.Addr().Interface(), srcVal.Field(i).Interface()); err != nil {
                return err
            }
        }
        return nil
    case SliceTy:
        if dstVal.Kind() != reflect.Slice {
            return fmt.Errorf("abi: invalid dst value for unpack, want slice, got %s", dstVal.Kind())
        }
        slice := reflect.MakeSlice(dstVal.Type(), srcVal.Len(), srcVal.Len())
        for i := 0; i < slice.Len(); i++ {
            if err := unpack(t.Elem, slice.Index(i).Addr().Interface(), srcVal.Index(i).Interface()); err != nil {
                return err
            }
        }
        dstVal.Set(slice)
    case ArrayTy:
        if dstVal.Kind() != reflect.Array {
            return fmt.Errorf("abi: invalid dst value for unpack, want array, got %s", dstVal.Kind())
        }
        array := reflect.New(dstVal.Type()).Elem()
        for i := 0; i < array.Len(); i++ {
            if err := unpack(t.Elem, array.Index(i).Addr().Interface(), srcVal.Index(i).Interface()); err != nil {
                return err
            }
        }
        dstVal.Set(array)
    }
    return nil
}

// unpackIntoMap unpacks marshalledValues into the provided map[string]interface{}
func (arguments Arguments) unpackIntoMap(v map[string]interface{}, marshalledValues []interface{}) error {
    // Make sure map is not nil
    if v == nil {
        return fmt.Errorf("abi: cannot unpack into a nil map")
    }

    for i, arg := range arguments.NonIndexed() {
        v[arg.Name] = marshalledValues[i]
    }
    return nil
}

// unpackAtomic unpacks ( hexdata -> go ) a single value
func (arguments Arguments) unpackAtomic(v interface{}, marshalledValues interface{}) error {
    if arguments.LengthNonIndexed() == 0 {
        return nil
    }
    argument := arguments.NonIndexed()[0]
    elem := reflect.ValueOf(v).Elem()

    if elem.Kind() == reflect.Struct {
        fieldmap, err := mapArgNamesToStructFields([]string{argument.Name}, elem)
        if err != nil {
            return err
        }
        field := elem.FieldByName(fieldmap[argument.Name])
        if !field.IsValid() {
            return fmt.Errorf("abi: field %s can't be found in the given value", argument.Name)
        }
        return unpack(&argument.Type, field.Addr().Interface(), marshalledValues)
    }
    return unpack(&argument.Type, elem.Addr().Interface(), marshalledValues)
}

// unpackTuple unpacks ( hexdata -> go ) a batch of values.
func (arguments Arguments) unpackTuple(v interface{}, marshalledValues []interface{}) error {
    var (
        value = reflect.ValueOf(v).Elem()
        typ   = value.Type()
        kind  = value.Kind()
    )
    if err := requireUnpackKind(value, typ, kind, arguments); err != nil {
        return err
    }

    // If the interface is a struct, get of abi->struct_field mapping
    var abi2struct map[string]string
    if kind == reflect.Struct {
        var (
            argNames []string
            err      error
        )
        for _, arg := range arguments.NonIndexed() {
            argNames = append(argNames, arg.Name)
        }
        abi2struct, err = mapArgNamesToStructFields(argNames, value)
        if err != nil {
            return err
        }
    }
    for i, arg := range arguments.NonIndexed() {
        switch kind {
        case reflect.Struct:
            field := value.FieldByName(abi2struct[arg.Name])
            if !field.IsValid() {
                return fmt.Errorf("abi: field %s can't be found in the given value", arg.Name)
            }
            if err := unpack(&arg.Type, field.Addr().Interface(), marshalledValues[i]); 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, reflect.ValueOf(marshalledValues[i])); err != nil {
                return err
            }
            if err := unpack(&arg.Type, v.Addr().Interface(), marshalledValues[i]); err != nil {
                return err
            }
        default:
            return fmt.Errorf("abi:[2] cannot unmarshal tuple in to %v", typ)
        }
    }
    return nil

}

// UnpackValues can be used to unpack ABI-encoded hexdata according to the ABI-specification,
// without supplying a struct to unpack into. Instead, this method returns a list containing the
// values. An atomic argument will be a list with one element.
func (arguments Arguments) UnpackValues(data []byte) ([]interface{}, error) {
    retval := make([]interface{}, 0, arguments.LengthNonIndexed())
    virtualArgs := 0
    for index, arg := range arguments.NonIndexed() {
        marshalledValue, err := toGoType((index+virtualArgs)*32, arg.Type, data)
        if arg.Type.T == ArrayTy && !isDynamicType(arg.Type) {
            // If we have a static array, like [3]uint256, these are coded as
            // just like uint256,uint256,uint256.
            // This means that we need to add two 'virtual' arguments when
            // we count the index from now on.
            //
            // Array values nested multiple levels deep are also encoded inline:
            // [2][3]uint256: uint256,uint256,uint256,uint256,uint256,uint256
            //
            // Calculate the full array size to get the correct offset for the next argument.
            // Decrement it by 1, as the normal index increment is still applied.
            virtualArgs += getTypeSize(arg.Type)/32 - 1
        } else if arg.Type.T == TupleTy && !isDynamicType(arg.Type) {
            // If we have a static tuple, like (uint256, bool, uint256), these are
            // coded as just like uint256,bool,uint256
            virtualArgs += getTypeSize(arg.Type)/32 - 1
        }
        if err != nil {
            return nil, err
        }
        retval = append(retval, marshalledValue)
    }
    return retval, nil
}

// PackValues performs the operation Go format -> Hexdata
// It is the semantic opposite of UnpackValues
func (arguments Arguments) PackValues(args []interface{}) ([]byte, error) {
    return arguments.Pack(args...)
}

// Pack 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 {
        inputOffset += getTypeSize(abiArg.Type)
    }
    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 dynamic types
        if isDynamicType(input.Type) {
            // set the offset
            ret = append(ret, packNum(reflect.ValueOf(inputOffset))...)
            // calculate next offset
            inputOffset += len(packed)
            // append to variable 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
}

// ToCamelCase converts an under-score string to a camel-case string
func ToCamelCase(input string) string {
    parts := strings.Split(input, "_")
    for i, s := range parts {
        if len(s) > 0 {
            parts[i] = strings.ToUpper(s[:1]) + s[1:]
        }
    }
    return strings.Join(parts, "")
}