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