1package common
  2
  3import (
  4	"math/big"
  5
  6	ethCommon "github.com/ethereum/go-ethereum/common"
  7	"github.com/iden3/go-iden3-crypto/babyjub"
  8)
  9
 10const (
 11	fromBJJCompressedB = 256
 12	fromEthAddrB       = 160
 13	f16B               = 16
 14	tokenIDB           = 32
 15	cidXB              = 32
 16)
 17
 18// L1Tx is a struct that represents a L1 tx
 19type L1Tx struct {
 20	// Stored in DB: mandatory fileds
 21	TxID            TxID               `meddler:"tx_id"`
 22	ToForgeL1TxsNum uint32             `meddler:"to_forge_l1_txs_num"` // toForgeL1TxsNum in which the tx was forged / will be forged
 23	Position        int                `meddler:"position"`
 24	UserOrigin      bool               `meddler:"user_origin"` // true if the tx was originated by a user, false if it was aoriginated by a coordinator. Note that this differ from the spec for implementation simplification purpposes
 25	FromIdx         Idx                `meddler:"from_idx"`    // FromIdx is used by L1Tx/Deposit to indicate the Idx receiver of the L1Tx.LoadAmount (deposit)
 26	FromEthAddr     ethCommon.Address  `meddler:"from_eth_addr"`
 27	FromBJJ         *babyjub.PublicKey `meddler:"from_bjj"`
 28	ToIdx           Idx                `meddler:"to_idx"` // ToIdx is ignored in L1Tx/Deposit, but used in the L1Tx/DepositAndTransfer
 29	TokenID         TokenID            `meddler:"token_id"`
 30	Amount          *big.Int           `meddler:"amount,bigint"`
 31	LoadAmount      *big.Int           `meddler:"load_amount,bigint"`
 32	EthBlockNum     uint64             `meddler:"eth_block_num"` // Ethereum Block Number in which this L1Tx was added to the queue
 33	Type            TxType             `meddler:"tx_type"`
 34	BatchNum        BatchNum           `meddler:"-"`
 35}
 36
 37// Tx returns a *Tx from the L1Tx
 38func (tx *L1Tx) Tx() *Tx {
 39	return &Tx{
 40		TxID:    tx.TxID,
 41		FromIdx: tx.FromIdx,
 42		ToIdx:   tx.ToIdx,
 43		Amount:  tx.Amount,
 44		Type:    tx.Type,
 45	}
 46}
 47
 48// Bytes encodes a L1Tx into []byte
 49func (tx *L1Tx) Bytes(nLevels int) []byte {
 50	res := big.NewInt(0)
 51	res = res.Add(res, big.NewInt(0).Or(big.NewInt(0), tx.ToIdx.BigInt()))
 52	res = res.Add(res, big.NewInt(0).Lsh(big.NewInt(0).Or(big.NewInt(0), big.NewInt(int64(tx.TokenID))), uint(nLevels)))
 53	res = res.Add(res, big.NewInt(0).Lsh(big.NewInt(0).Or(big.NewInt(0), tx.Amount), uint(nLevels+tokenIDB)))
 54	res = res.Add(res, big.NewInt(0).Lsh(big.NewInt(0).Or(big.NewInt(0), tx.LoadAmount), uint(nLevels+tokenIDB+f16B)))
 55	res = res.Add(res, big.NewInt(0).Lsh(big.NewInt(0).Or(big.NewInt(0), tx.FromIdx.BigInt()), uint(nLevels+tokenIDB+2*f16B)))
 56
 57	fromBJJ := big.NewInt(0)
 58	fromBJJ.SetString(tx.FromBJJ.String(), 16)
 59	fromBJJCompressed := big.NewInt(0).Or(big.NewInt(0), fromBJJ)
 60	res = res.Add(res, big.NewInt(0).Lsh(fromBJJCompressed, uint(2*nLevels+tokenIDB+2*f16B)))
 61
 62	fromEthAddr := big.NewInt(0).Or(big.NewInt(0), tx.FromEthAddr.Hash().Big())
 63	res = res.Add(res, big.NewInt(0).Lsh(fromEthAddr, uint(fromBJJCompressedB+2*nLevels+tokenIDB+2*f16B)))
 64
 65	return res.Bytes()
 66}
 67
 68// L1TxFromBytes decodes a L1Tx from []byte
 69func L1TxFromBytes(l1TxEncoded []byte) (*L1Tx, error) {
 70	l1Tx := &L1Tx{}
 71	var idxB uint = cidXB
 72
 73	l1TxEncodedBI := big.NewInt(0)
 74	l1TxEncodedBI.SetBytes(l1TxEncoded)
 75
 76	toIdx, err := IdxFromBigInt(extract(l1TxEncodedBI, 0, idxB))
 77
 78	if err != nil {
 79		return nil, err
 80	}
 81
 82	l1Tx.ToIdx = toIdx
 83
 84	l1Tx.TokenID = TokenID(extract(l1TxEncodedBI, idxB, tokenIDB).Uint64())
 85	l1Tx.Amount = extract(l1TxEncodedBI, idxB+tokenIDB, f16B)
 86	l1Tx.LoadAmount = extract(l1TxEncodedBI, idxB+tokenIDB+f16B, f16B)
 87	fromIdx, err := IdxFromBigInt(extract(l1TxEncodedBI, idxB+tokenIDB+2*f16B, f16B))
 88
 89	if err != nil {
 90		return nil, err
 91	}
 92
 93	l1Tx.FromIdx = fromIdx
 94
 95	var pkComp babyjub.PublicKeyComp
 96	copy(pkComp[:], extract(l1TxEncodedBI, 2*idxB+tokenIDB+2*f16B, fromBJJCompressedB).Bytes())
 97	pk, err := pkComp.Decompress()
 98
 99	if err != nil {
100		return nil, err
101	}
102
103	l1Tx.FromBJJ = pk
104
105	l1Tx.FromEthAddr = ethCommon.BigToAddress(extract(l1TxEncodedBI, fromBJJCompressedB+2*idxB+tokenIDB+2*f16B, fromEthAddrB))
106
107	return l1Tx, nil
108}
109
110// extract masks and shifts a bigInt
111func extract(num *big.Int, origin uint, len uint) *big.Int {
112	mask := big.NewInt(0).Sub(big.NewInt(0).Lsh(big.NewInt(1), len), big.NewInt(1))
113	return big.NewInt(0).And(big.NewInt(0).Rsh(num, origin), mask)
114}