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// Copyright (C) 2019-2022 Algorand, Inc.
// This file is part of go-algorand
//
// go-algorand is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// go-algorand 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 Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with go-algorand. If not, see <https://www.gnu.org/licenses/>.
package transactions
import (
"errors"
"fmt"
"github.com/algorand/go-algorand/crypto"
"github.com/algorand/go-algorand/data/basics"
"github.com/algorand/go-algorand/protocol"
)
// SignedTxn wraps a transaction and a signature.
// It exposes a Verify() method that verifies the signature and checks that the
// underlying transaction is well-formed.
// TODO: update this documentation now that there's multisig
type SignedTxn struct {
_struct struct{} `codec:",omitempty,omitemptyarray"`
Sig crypto.Signature `codec:"sig"`
Msig crypto.MultisigSig `codec:"msig"`
Lsig LogicSig `codec:"lsig"`
Txn Transaction `codec:"txn"`
AuthAddr basics.Address `codec:"sgnr"`
}
// SignedTxnInBlock is how a signed transaction is encoded in a block.
type SignedTxnInBlock struct {
_struct struct{} `codec:",omitempty,omitemptyarray"`
SignedTxnWithAD
HasGenesisID bool `codec:"hgi"`
HasGenesisHash bool `codec:"hgh"`
}
// SignedTxnWithAD is a (decoded) SignedTxn with associated ApplyData
type SignedTxnWithAD struct {
_struct struct{} `codec:",omitempty,omitemptyarray"`
SignedTxn
ApplyData
}
// ID returns the Txid (i.e., hash) of the underlying transaction.
func (s SignedTxn) ID() Txid {
return s.Txn.ID()
}
// ID on SignedTxnInBlock should never be called, because the ID depends
// on the block from which this transaction will be decoded. By having
// a different return value from SignedTxn.ID(), we will catch errors at
// compile-time.
func (s SignedTxnInBlock) ID() {
}
// GetEncodedLength returns the length in bytes of the encoded transaction
func (s SignedTxn) GetEncodedLength() int {
enc := s.MarshalMsg(protocol.GetEncodingBuf())
defer protocol.PutEncodingBuf(enc)
return len(enc)
}
// GetEncodedLength returns the length in bytes of the encoded transaction
func (s SignedTxnInBlock) GetEncodedLength() int {
enc := s.MarshalMsg(protocol.GetEncodingBuf())
defer protocol.PutEncodingBuf(enc)
return len(enc)
}
// Authorizer returns the address against which the signature/msig/lsig should be checked,
// or so the SignedTxn claims.
// This is just s.AuthAddr or, if s.AuthAddr is zero, s.Txn.Sender.
// It's provided as a convenience method.
func (s SignedTxn) Authorizer() basics.Address {
if s.AuthAddr.IsZero() {
return s.Txn.Sender
}
return s.AuthAddr
}
// AssembleSignedTxn assembles a multisig-signed transaction from a transaction an optional sig, and an optional multisig.
// No signature checking is done -- for example, this might only be a partial multisig
// TODO: is this method used anywhere, or is it safe to remove?
func AssembleSignedTxn(txn Transaction, sig crypto.Signature, msig crypto.MultisigSig) (SignedTxn, error) {
if sig != (crypto.Signature{}) && !msig.Blank() {
return SignedTxn{}, errors.New("signed txn can only have one of sig or msig")
}
s := SignedTxn{
Txn: txn,
Sig: sig,
Msig: msig,
}
return s, nil
}
// ToBeHashed implements the crypto.Hashable interface.
func (s *SignedTxnInBlock) ToBeHashed() (protocol.HashID, []byte) {
return protocol.SignedTxnInBlock, protocol.Encode(s)
}
// Hash implements an optimized version of crypto.HashObj(s).
func (s *SignedTxnInBlock) Hash() crypto.Digest {
enc := s.MarshalMsg(append(protocol.GetEncodingBuf(), []byte(protocol.SignedTxnInBlock)...))
defer protocol.PutEncodingBuf(enc)
return crypto.Hash(enc)
}
// WrapSignedTxnsWithAD takes an array SignedTxn and returns the same as SignedTxnWithAD
// Each txn's ApplyData is the default empty state.
func WrapSignedTxnsWithAD(txgroup []SignedTxn) []SignedTxnWithAD {
txgroupad := make([]SignedTxnWithAD, len(txgroup))
for i, tx := range txgroup {
txgroupad[i].SignedTxn = tx
}
return txgroupad
}
// FeeCredit computes the amount of fee credit that can be spent on
// inner txns because it was more than required.
func FeeCredit(txgroup []SignedTxnWithAD, minFee uint64) (uint64, error) {
minFeeCount := uint64(0)
feesPaid := uint64(0)
for _, stxn := range txgroup {
if stxn.Txn.Type != protocol.CompactCertTx {
minFeeCount++
}
feesPaid = basics.AddSaturate(feesPaid, stxn.Txn.Fee.Raw)
}
feeNeeded, overflow := basics.OMul(minFee, minFeeCount)
if overflow {
return 0, fmt.Errorf("txgroup fee requirement overflow")
}
// feesPaid may have saturated. That's ok. Since we know
// feeNeeded did not overflow, simple comparison tells us
// feesPaid was enough.
if feesPaid < feeNeeded {
return 0, fmt.Errorf("txgroup had %d in fees, which is less than the minimum %d * %d",
feesPaid, minFeeCount, minFee)
}
// Now, if feesPaid *did* saturate, you will not get "credit" for
// all those fees while executing AVM code that might create
// transactions. But you'll get the max uint64 - good luck
// spending it.
return feesPaid - feeNeeded, nil
}
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