256 lines
8.7 KiB
Go
256 lines
8.7 KiB
Go
// 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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"bytes"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/crypto"
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)
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// The ABI holds information about a contract's context and available
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// invokable methods. It will allow you to type check function calls and
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// packs data accordingly.
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type ABI struct {
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Constructor Method
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Methods map[string]Method
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Events map[string]Event
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Errors map[string]Error
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// Additional "special" functions introduced in solidity v0.6.0.
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// It's separated from the original default fallback. Each contract
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// can only define one fallback and receive function.
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Fallback Method // Note it's also used to represent legacy fallback before v0.6.0
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Receive Method
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}
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// JSON returns a parsed ABI interface and error if it failed.
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func JSON(reader io.Reader) (ABI, error) {
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dec := json.NewDecoder(reader)
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var abi ABI
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if err := dec.Decode(&abi); err != nil {
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return ABI{}, err
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}
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return abi, nil
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}
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// Pack the given method name to conform the ABI. Method call's data
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// will consist of method_id, args0, arg1, ... argN. Method id consists
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// of 4 bytes and arguments are all 32 bytes.
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// Method ids are created from the first 4 bytes of the hash of the
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// methods string signature. (signature = baz(uint32,string32))
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func (abi ABI) Pack(name string, args ...interface{}) ([]byte, error) {
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// Fetch the ABI of the requested method
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if name == "" {
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// constructor
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arguments, err := abi.Constructor.Inputs.Pack(args...)
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if err != nil {
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return nil, err
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}
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return arguments, nil
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}
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method, exist := abi.Methods[name]
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if !exist {
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return nil, fmt.Errorf("method '%s' not found", name)
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}
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arguments, err := method.Inputs.Pack(args...)
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if err != nil {
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return nil, err
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}
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// Pack up the method ID too if not a constructor and return
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return append(method.ID, arguments...), nil
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}
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func (abi ABI) getArguments(name string, data []byte) (Arguments, error) {
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// since there can't be naming collisions with contracts and events,
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// we need to decide whether we're calling a method or an event
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var args Arguments
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if method, ok := abi.Methods[name]; ok {
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if len(data)%32 != 0 {
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return nil, fmt.Errorf("abi: improperly formatted output: %s - Bytes: [%+v]", string(data), data)
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}
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args = method.Outputs
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}
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if event, ok := abi.Events[name]; ok {
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args = event.Inputs
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}
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if args == nil {
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return nil, fmt.Errorf("abi: could not locate named method or event: %s", name)
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}
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return args, nil
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}
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// Unpack unpacks the output according to the abi specification.
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func (abi ABI) Unpack(name string, data []byte) ([]interface{}, error) {
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args, err := abi.getArguments(name, data)
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if err != nil {
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return nil, err
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}
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return args.Unpack(data)
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}
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// UnpackIntoInterface unpacks the output in v according to the abi specification.
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// It performs an additional copy. Please only use, if you want to unpack into a
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// structure that does not strictly conform to the abi structure (e.g. has additional arguments)
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func (abi ABI) UnpackIntoInterface(v interface{}, name string, data []byte) error {
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args, err := abi.getArguments(name, data)
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if err != nil {
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return err
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}
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unpacked, err := args.Unpack(data)
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if err != nil {
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return err
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}
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return args.Copy(v, unpacked)
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}
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// UnpackIntoMap unpacks a log into the provided map[string]interface{}.
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func (abi ABI) UnpackIntoMap(v map[string]interface{}, name string, data []byte) (err error) {
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args, err := abi.getArguments(name, data)
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if err != nil {
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return err
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}
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return args.UnpackIntoMap(v, data)
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}
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// UnmarshalJSON implements json.Unmarshaler interface.
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func (abi *ABI) UnmarshalJSON(data []byte) error {
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var fields []struct {
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Type string
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Name string
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Inputs []Argument
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Outputs []Argument
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// Status indicator which can be: "pure", "view",
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// "nonpayable" or "payable".
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StateMutability string
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// Deprecated Status indicators, but removed in v0.6.0.
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Constant bool // True if function is either pure or view
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Payable bool // True if function is payable
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// Event relevant indicator represents the event is
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// declared as anonymous.
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Anonymous bool
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}
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if err := json.Unmarshal(data, &fields); err != nil {
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return err
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}
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abi.Methods = make(map[string]Method)
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abi.Events = make(map[string]Event)
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abi.Errors = make(map[string]Error)
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for _, field := range fields {
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switch field.Type {
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case "constructor":
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abi.Constructor = NewMethod("", "", Constructor, field.StateMutability, field.Constant, field.Payable, field.Inputs, nil)
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case "function":
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name := ResolveNameConflict(field.Name, func(s string) bool { _, ok := abi.Methods[s]; return ok })
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abi.Methods[name] = NewMethod(name, field.Name, Function, field.StateMutability, field.Constant, field.Payable, field.Inputs, field.Outputs)
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case "fallback":
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// New introduced function type in v0.6.0, check more detail
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// here https://solidity.readthedocs.io/en/v0.6.0/contracts.html#fallback-function
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if abi.HasFallback() {
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return errors.New("only single fallback is allowed")
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}
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abi.Fallback = NewMethod("", "", Fallback, field.StateMutability, field.Constant, field.Payable, nil, nil)
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case "receive":
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// New introduced function type in v0.6.0, check more detail
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// here https://solidity.readthedocs.io/en/v0.6.0/contracts.html#fallback-function
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if abi.HasReceive() {
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return errors.New("only single receive is allowed")
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}
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if field.StateMutability != "payable" {
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return errors.New("the statemutability of receive can only be payable")
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}
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abi.Receive = NewMethod("", "", Receive, field.StateMutability, field.Constant, field.Payable, nil, nil)
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case "event":
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name := ResolveNameConflict(field.Name, func(s string) bool { _, ok := abi.Events[s]; return ok })
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abi.Events[name] = NewEvent(name, field.Name, field.Anonymous, field.Inputs)
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case "error":
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// Errors cannot be overloaded or overridden but are inherited,
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// no need to resolve the name conflict here.
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abi.Errors[field.Name] = NewError(field.Name, field.Inputs)
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default:
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return fmt.Errorf("abi: could not recognize type %v of field %v", field.Type, field.Name)
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}
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}
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return nil
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}
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// MethodById looks up a method by the 4-byte id,
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// returns nil if none found.
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func (abi *ABI) MethodById(sigdata []byte) (*Method, error) {
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if len(sigdata) < 4 {
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return nil, fmt.Errorf("data too short (%d bytes) for abi method lookup", len(sigdata))
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}
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for _, method := range abi.Methods {
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if bytes.Equal(method.ID, sigdata[:4]) {
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return &method, nil
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}
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}
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return nil, fmt.Errorf("no method with id: %#x", sigdata[:4])
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}
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// EventByID looks an event up by its topic hash in the
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// ABI and returns nil if none found.
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func (abi *ABI) EventByID(topic common.Hash) (*Event, error) {
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for _, event := range abi.Events {
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if bytes.Equal(event.ID.Bytes(), topic.Bytes()) {
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return &event, nil
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}
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}
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return nil, fmt.Errorf("no event with id: %#x", topic.Hex())
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}
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// HasFallback returns an indicator whether a fallback function is included.
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func (abi *ABI) HasFallback() bool {
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return abi.Fallback.Type == Fallback
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}
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// HasReceive returns an indicator whether a receive function is included.
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func (abi *ABI) HasReceive() bool {
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return abi.Receive.Type == Receive
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}
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// revertSelector is a special function selector for revert reason unpacking.
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var revertSelector = crypto.Keccak256([]byte("Error(string)"))[:4]
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// UnpackRevert resolves the abi-encoded revert reason. According to the solidity
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// spec https://solidity.readthedocs.io/en/latest/control-structures.html#revert,
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// the provided revert reason is abi-encoded as if it were a call to a function
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// `Error(string)`. So it's a special tool for it.
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func UnpackRevert(data []byte) (string, error) {
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if len(data) < 4 {
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return "", errors.New("invalid data for unpacking")
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}
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if !bytes.Equal(data[:4], revertSelector) {
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return "", errors.New("invalid data for unpacking")
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}
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typ, _ := NewType("string", "", nil)
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unpacked, err := (Arguments{{Type: typ}}).Unpack(data[4:])
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if err != nil {
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return "", err
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}
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return unpacked[0].(string), nil
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}
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