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hermez-node/db/statedb/txprocessors.go
db/statedb/txprocessors.goRaw
  1package statedb
  2
  3import (
  4	"bytes"
  5	"errors"
  6	"math/big"
  7
  8	ethCommon "github.com/ethereum/go-ethereum/common"
  9	"github.com/hermeznetwork/hermez-node/common"
 10	"github.com/hermeznetwork/hermez-node/log"
 11	"github.com/iden3/go-iden3-crypto/babyjub"
 12	"github.com/iden3/go-iden3-crypto/poseidon"
 13	"github.com/iden3/go-merkletree"
 14	"github.com/iden3/go-merkletree/db"
 15	"github.com/iden3/go-merkletree/db/memory"
 16)
 17
 18var (
 19	// keyidx is used as key in the db to store the current Idx
 20	keyidx = []byte("idx")
 21
 22	// ffAddr    = ethCommon.HexToAddress("0xffffffffffffffffffffffffffffffffffffffff")
 23	emptyAddr = ethCommon.HexToAddress("0x0000000000000000000000000000000000000000")
 24)
 25
 26func (s *StateDB) resetZKInputs() {
 27	s.zki = nil
 28	s.i = 0
 29}
 30
 31type processedExit struct {
 32	exit    bool
 33	newExit bool
 34	idx     common.Idx
 35	acc     common.Account
 36}
 37
 38// ProcessTxs process the given L1Txs & L2Txs applying the needed updates to
 39// the StateDB depending on the transaction Type. Returns the common.ZKInputs
 40// to generate the SnarkProof later used by the BatchBuilder, and if
 41// cmpExitTree is set to true, returns common.ExitTreeLeaf that is later used
 42// by the Synchronizer to update the HistoryDB.
 43func (s *StateDB) ProcessTxs(cmpExitTree, cmpZKInputs bool, l1usertxs, l1coordinatortxs []*common.L1Tx, l2txs []*common.PoolL2Tx) (*common.ZKInputs, []*common.ExitInfo, error) {
 44	var err error
 45	var exitTree *merkletree.MerkleTree
 46
 47	if s.zki != nil {
 48		return nil, nil, errors.New("Expected StateDB.zki==nil, something went wrong and it's not empty")
 49	}
 50	defer s.resetZKInputs()
 51
 52	nTx := len(l1usertxs) + len(l1coordinatortxs) + len(l2txs)
 53	if nTx == 0 {
 54		// TODO return ZKInputs of batch without txs
 55		return nil, nil, nil
 56	}
 57	exits := make([]processedExit, nTx)
 58
 59	if cmpZKInputs {
 60		s.zki = common.NewZKInputs(nTx, 24, 32) // TODO this values will be parameters of the function, taken from config file/coordinator call
 61		s.zki.OldLastIdx = (s.idx - 1).BigInt()
 62		s.zki.OldStateRoot = s.mt.Root().BigInt()
 63	}
 64
 65	// TBD if ExitTree is only in memory or stored in disk, for the moment
 66	// only needed in memory
 67	if cmpExitTree {
 68		exitTree, err = merkletree.NewMerkleTree(memory.NewMemoryStorage(), s.mt.MaxLevels())
 69		if err != nil {
 70			return nil, nil, err
 71		}
 72	}
 73
 74	// assumption: l1usertx are sorted by L1Tx.Position
 75	for _, tx := range l1usertxs {
 76		exitIdx, exitAccount, newExit, err := s.processL1Tx(exitTree, tx)
 77		if err != nil {
 78			return nil, nil, err
 79		}
 80		if exitIdx != nil && cmpExitTree {
 81			exits[s.i] = processedExit{
 82				exit:    true,
 83				newExit: newExit,
 84				idx:     *exitIdx,
 85				acc:     *exitAccount,
 86			}
 87		}
 88		if s.zki != nil {
 89			s.i++
 90		}
 91	}
 92	for _, tx := range l1coordinatortxs {
 93		exitIdx, exitAccount, newExit, err := s.processL1Tx(exitTree, tx)
 94		if err != nil {
 95			return nil, nil, err
 96		}
 97		if exitIdx != nil {
 98			log.Error("Unexpected Exit in L1CoordinatorTx")
 99		}
100		if exitIdx != nil && cmpExitTree {
101			exits[s.i] = processedExit{
102				exit:    true,
103				newExit: newExit,
104				idx:     *exitIdx,
105				acc:     *exitAccount,
106			}
107		}
108		if s.zki != nil {
109			s.i++
110		}
111	}
112	for _, tx := range l2txs {
113		exitIdx, exitAccount, newExit, err := s.processL2Tx(exitTree, tx)
114		if err != nil {
115			return nil, nil, err
116		}
117		if exitIdx != nil && cmpExitTree {
118			exits[s.i] = processedExit{
119				exit:    true,
120				newExit: newExit,
121				idx:     *exitIdx,
122				acc:     *exitAccount,
123			}
124		}
125		if s.zki != nil {
126			s.i++
127		}
128	}
129
130	if !cmpExitTree && !cmpZKInputs {
131		return nil, nil, nil
132	}
133
134	// once all txs processed (exitTree root frozen), for each Exit,
135	// generate common.ExitInfo data
136	var exitInfos []*common.ExitInfo
137	for i := 0; i < nTx; i++ {
138		if !exits[i].exit {
139			continue
140		}
141		exitIdx := exits[i].idx
142		exitAccount := exits[i].acc
143
144		// 0. generate MerkleProof
145		p, err := exitTree.GenerateCircomVerifierProof(exitIdx.BigInt(), nil)
146		if err != nil {
147			return nil, nil, err
148		}
149		// 1. compute nullifier
150		exitAccStateValue, err := exitAccount.HashValue()
151		if err != nil {
152			return nil, nil, err
153		}
154		nullifier, err := poseidon.Hash([]*big.Int{
155			exitAccStateValue,
156			big.NewInt(int64(s.currentBatch)),
157			exitTree.Root().BigInt(),
158		})
159		if err != nil {
160			return nil, nil, err
161		}
162		// 2. generate common.ExitInfo
163		ei := &common.ExitInfo{
164			AccountIdx:  exitIdx,
165			MerkleProof: p,
166			Nullifier:   nullifier,
167			Balance:     exitAccount.Balance,
168		}
169		exitInfos = append(exitInfos, ei)
170
171		if s.zki != nil {
172			s.zki.TokenID2[i] = exitAccount.TokenID.BigInt()
173			s.zki.Nonce2[i] = exitAccount.Nonce.BigInt()
174			if babyjub.PointCoordSign(exitAccount.PublicKey.X) {
175				s.zki.Sign2[i] = big.NewInt(1)
176			}
177			s.zki.Ay2[i] = exitAccount.PublicKey.Y
178			s.zki.Balance2[i] = exitAccount.Balance
179			s.zki.EthAddr2[i] = common.EthAddrToBigInt(exitAccount.EthAddr)
180			s.zki.Siblings2[i] = p.Siblings
181			if exits[i].newExit {
182				s.zki.NewExit[i] = big.NewInt(1)
183			}
184			if p.IsOld0 {
185				s.zki.IsOld0_2[i] = big.NewInt(1)
186			}
187			s.zki.OldKey2[i] = p.OldKey.BigInt()
188			s.zki.OldValue2[i] = p.OldValue.BigInt()
189		}
190	}
191	if !cmpZKInputs {
192		return nil, exitInfos, nil
193	}
194
195	// compute last ZKInputs parameters
196	s.zki.GlobalChainID = big.NewInt(0) // TODO, 0: ethereum, this will be get from config file
197	// zki.FeeIdxs = ? // TODO, this will be get from the config file
198	tokenIDs, err := s.getTokenIDsBigInt(l1usertxs, l1coordinatortxs, l2txs)
199	if err != nil {
200		return nil, nil, err
201	}
202	s.zki.FeePlanTokens = tokenIDs
203
204	// s.zki.ISInitStateRootFee = s.mt.Root().BigInt()
205
206	// TODO once the Node Config sets the Accounts where to send the Fees
207	// compute fees & update ZKInputs
208
209	// return exitInfos, so Synchronizer will be able to store it into
210	// HistoryDB for the concrete BatchNum
211	return s.zki, exitInfos, nil
212}
213
214// getTokenIDsBigInt returns the list of TokenIDs in *big.Int format
215func (s *StateDB) getTokenIDsBigInt(l1usertxs, l1coordinatortxs []*common.L1Tx, l2txs []*common.PoolL2Tx) ([]*big.Int, error) {
216	tokenIDs := make(map[common.TokenID]bool)
217	for i := 0; i < len(l1usertxs); i++ {
218		tokenIDs[l1usertxs[i].TokenID] = true
219	}
220	for i := 0; i < len(l1coordinatortxs); i++ {
221		tokenIDs[l1coordinatortxs[i].TokenID] = true
222	}
223	for i := 0; i < len(l2txs); i++ {
224		// as L2Tx does not have parameter TokenID, get it from the
225		// AccountsDB (in the StateDB)
226		acc, err := s.GetAccount(l2txs[i].ToIdx)
227		if err != nil {
228			return nil, err
229		}
230		tokenIDs[acc.TokenID] = true
231	}
232	var tBI []*big.Int
233	for t := range tokenIDs {
234		tBI = append(tBI, t.BigInt())
235	}
236	return tBI, nil
237}
238
239// processL1Tx process the given L1Tx applying the needed updates to the
240// StateDB depending on the transaction Type. It returns the 3 parameters
241// related to the Exit (in case of): Idx, ExitAccount, boolean determining if
242// the Exit created a new Leaf in the ExitTree.
243func (s *StateDB) processL1Tx(exitTree *merkletree.MerkleTree, tx *common.L1Tx) (*common.Idx, *common.Account, bool, error) {
244	// ZKInputs
245	if s.zki != nil {
246		// Txs
247		// s.zki.TxCompressedData[s.i] = tx.TxCompressedData() // uncomment once L1Tx.TxCompressedData is ready
248		s.zki.FromIdx[s.i] = tx.FromIdx.BigInt()
249		s.zki.ToIdx[s.i] = tx.ToIdx.BigInt()
250		s.zki.OnChain[s.i] = big.NewInt(1)
251
252		// L1Txs
253		s.zki.LoadAmountF[s.i] = tx.LoadAmount
254		s.zki.FromEthAddr[s.i] = common.EthAddrToBigInt(tx.FromEthAddr)
255		if tx.FromBJJ != nil {
256			s.zki.FromBJJCompressed[s.i] = BJJCompressedTo256BigInts(tx.FromBJJ.Compress())
257		}
258
259		// Intermediate States
260		s.zki.ISOnChain[s.i] = big.NewInt(1)
261	}
262
263	switch tx.Type {
264	case common.TxTypeForceTransfer, common.TxTypeTransfer:
265		// go to the MT account of sender and receiver, and update balance
266		// & nonce
267		err := s.applyTransfer(tx.Tx())
268		if err != nil {
269			return nil, nil, false, err
270		}
271	case common.TxTypeCreateAccountDeposit:
272		// add new account to the MT, update balance of the MT account
273		err := s.applyCreateAccount(tx)
274		if err != nil {
275			return nil, nil, false, err
276		}
277
278		if s.zki != nil {
279			s.zki.AuxFromIdx[s.i] = s.idx.BigInt() // last s.idx is the one used for creating the new account
280			s.zki.NewAccount[s.i] = big.NewInt(1)
281		}
282	case common.TxTypeDeposit:
283		// update balance of the MT account
284		err := s.applyDeposit(tx, false)
285		if err != nil {
286			return nil, nil, false, err
287		}
288	case common.TxTypeDepositTransfer:
289		// update balance in MT account, update balance & nonce of sender
290		// & receiver
291		err := s.applyDeposit(tx, true)
292		if err != nil {
293			return nil, nil, false, err
294		}
295	case common.TxTypeCreateAccountDepositTransfer:
296		// add new account to the merkletree, update balance in MT account,
297		// update balance & nonce of sender & receiver
298		err := s.applyCreateAccountDepositTransfer(tx)
299		if err != nil {
300			return nil, nil, false, err
301		}
302
303		if s.zki != nil {
304			s.zki.AuxFromIdx[s.i] = s.idx.BigInt() // last s.idx is the one used for creating the new account
305			s.zki.NewAccount[s.i] = big.NewInt(1)
306		}
307	case common.TxTypeExit:
308		// execute exit flow
309		exitAccount, newExit, err := s.applyExit(exitTree, tx.Tx())
310		if err != nil {
311			return nil, nil, false, err
312		}
313		return &tx.FromIdx, exitAccount, newExit, nil
314	default:
315	}
316
317	return nil, nil, false, nil
318}
319
320// processL2Tx process the given L2Tx applying the needed updates to the
321// StateDB depending on the transaction Type. It returns the 3 parameters
322// related to the Exit (in case of): Idx, ExitAccount, boolean determining if
323// the Exit created a new Leaf in the ExitTree.
324func (s *StateDB) processL2Tx(exitTree *merkletree.MerkleTree, tx *common.PoolL2Tx) (*common.Idx, *common.Account, bool, error) {
325	var err error
326	// ZKInputs
327	if s.zki != nil {
328		// Txs
329		// s.zki.TxCompressedData[s.i] = tx.TxCompressedData() // uncomment once L1Tx.TxCompressedData is ready
330		// s.zki.TxCompressedDataV2[s.i] = tx.TxCompressedDataV2() // uncomment once L2Tx.TxCompressedDataV2 is ready
331		s.zki.FromIdx[s.i] = tx.FromIdx.BigInt()
332		s.zki.ToIdx[s.i] = tx.ToIdx.BigInt()
333
334		// fill AuxToIdx if needed
335		if tx.ToIdx == common.Idx(0) {
336			var idx common.Idx
337			if !bytes.Equal(tx.ToEthAddr.Bytes(), emptyAddr.Bytes()) && tx.ToBJJ == nil {
338				// case ToEthAddr!=0 && ToBJJ=0
339				idx, err = s.GetIdxByEthAddr(tx.ToEthAddr)
340				if err != nil {
341					return nil, nil, false, ErrToIdxNotFound
342				}
343			} else if !bytes.Equal(tx.ToEthAddr.Bytes(), emptyAddr.Bytes()) && tx.ToBJJ != nil {
344				// case ToEthAddr!=0 && ToBJJ!=0
345				idx, err = s.GetIdxByEthAddrBJJ(tx.ToEthAddr, tx.ToBJJ)
346				if err != nil {
347					return nil, nil, false, ErrToIdxNotFound
348				}
349			} else {
350				// rest of cases (included case ToEthAddr==0) are not possible
351				return nil, nil, false, ErrToIdxNotFound
352			}
353			s.zki.AuxToIdx[s.i] = idx.BigInt()
354		}
355		s.zki.ToBJJAy[s.i] = tx.ToBJJ.Y
356		s.zki.ToEthAddr[s.i] = common.EthAddrToBigInt(tx.ToEthAddr)
357
358		s.zki.OnChain[s.i] = big.NewInt(0)
359		s.zki.NewAccount[s.i] = big.NewInt(0)
360
361		// L2Txs
362		// s.zki.RqOffset[s.i] =  // TODO Rq once TxSelector is ready
363		// s.zki.RqTxCompressedDataV2[s.i] = // TODO
364		// s.zki.RqToEthAddr[s.i] = common.EthAddrToBigInt(tx.RqToEthAddr) // TODO
365		// s.zki.RqToBJJAy[s.i] = tx.ToBJJ.Y // TODO
366		s.zki.S[s.i] = tx.Signature.S
367		s.zki.R8x[s.i] = tx.Signature.R8.X
368		s.zki.R8y[s.i] = tx.Signature.R8.Y
369	}
370
371	switch tx.Type {
372	case common.TxTypeTransfer:
373		// go to the MT account of sender and receiver, and update
374		// balance & nonce
375		err = s.applyTransfer(tx.Tx())
376		if err != nil {
377			return nil, nil, false, err
378		}
379	case common.TxTypeExit:
380		// execute exit flow
381		exitAccount, newExit, err := s.applyExit(exitTree, tx.Tx())
382		if err != nil {
383			return nil, nil, false, err
384		}
385		return &tx.FromIdx, exitAccount, newExit, nil
386	default:
387	}
388	return nil, nil, false, nil
389}
390
391// applyCreateAccount creates a new account in the account of the depositer, it
392// stores the deposit value
393func (s *StateDB) applyCreateAccount(tx *common.L1Tx) error {
394	account := &common.Account{
395		TokenID:   tx.TokenID,
396		Nonce:     0,
397		Balance:   tx.LoadAmount,
398		PublicKey: tx.FromBJJ,
399		EthAddr:   tx.FromEthAddr,
400	}
401
402	p, err := s.CreateAccount(common.Idx(s.idx+1), account)
403	if err != nil {
404		return err
405	}
406	if s.zki != nil {
407		s.zki.TokenID1[s.i] = tx.TokenID.BigInt()
408		s.zki.Nonce1[s.i] = big.NewInt(0)
409		if babyjub.PointCoordSign(tx.FromBJJ.X) {
410			s.zki.Sign1[s.i] = big.NewInt(1)
411		}
412		s.zki.Ay1[s.i] = tx.FromBJJ.Y
413		s.zki.Balance1[s.i] = tx.LoadAmount
414		s.zki.EthAddr1[s.i] = common.EthAddrToBigInt(tx.FromEthAddr)
415		s.zki.Siblings1[s.i] = siblingsToZKInputFormat(p.Siblings)
416		if p.IsOld0 {
417			s.zki.IsOld0_1[s.i] = big.NewInt(1)
418		}
419		s.zki.OldKey1[s.i] = p.OldKey.BigInt()
420		s.zki.OldValue1[s.i] = p.OldValue.BigInt()
421	}
422
423	s.idx = s.idx + 1
424	return s.setIdx(s.idx)
425}
426
427// applyDeposit updates the balance in the account of the depositer, if
428// andTransfer parameter is set to true, the method will also apply the
429// Transfer of the L1Tx/DepositTransfer
430func (s *StateDB) applyDeposit(tx *common.L1Tx, transfer bool) error {
431	// deposit the tx.LoadAmount into the sender account
432	accSender, err := s.GetAccount(tx.FromIdx)
433	if err != nil {
434		return err
435	}
436	accSender.Balance = new(big.Int).Add(accSender.Balance, tx.LoadAmount)
437
438	// in case that the tx is a L1Tx>DepositTransfer
439	var accReceiver *common.Account
440	if transfer {
441		accReceiver, err = s.GetAccount(tx.ToIdx)
442		if err != nil {
443			return err
444		}
445		// subtract amount to the sender
446		accSender.Balance = new(big.Int).Sub(accSender.Balance, tx.Amount)
447		// add amount to the receiver
448		accReceiver.Balance = new(big.Int).Add(accReceiver.Balance, tx.Amount)
449	}
450	// update sender account in localStateDB
451	p, err := s.UpdateAccount(tx.FromIdx, accSender)
452	if err != nil {
453		return err
454	}
455	if s.zki != nil {
456		s.zki.TokenID1[s.i] = accSender.TokenID.BigInt()
457		s.zki.Nonce1[s.i] = accSender.Nonce.BigInt()
458		if babyjub.PointCoordSign(accSender.PublicKey.X) {
459			s.zki.Sign1[s.i] = big.NewInt(1)
460		}
461		s.zki.Ay1[s.i] = accSender.PublicKey.Y
462		s.zki.Balance1[s.i] = accSender.Balance
463		s.zki.EthAddr1[s.i] = common.EthAddrToBigInt(accSender.EthAddr)
464		s.zki.Siblings1[s.i] = siblingsToZKInputFormat(p.Siblings)
465		// IsOld0_1, OldKey1, OldValue1 not needed as this is not an insert
466	}
467
468	// this is done after updating Sender Account (depositer)
469	if transfer {
470		// update receiver account in localStateDB
471		p, err := s.UpdateAccount(tx.ToIdx, accReceiver)
472		if err != nil {
473			return err
474		}
475		if s.zki != nil {
476			s.zki.TokenID2[s.i] = accReceiver.TokenID.BigInt()
477			s.zki.Nonce2[s.i] = accReceiver.Nonce.BigInt()
478			if babyjub.PointCoordSign(accReceiver.PublicKey.X) {
479				s.zki.Sign2[s.i] = big.NewInt(1)
480			}
481			s.zki.Ay2[s.i] = accReceiver.PublicKey.Y
482			s.zki.Balance2[s.i] = accReceiver.Balance
483			s.zki.EthAddr2[s.i] = common.EthAddrToBigInt(accReceiver.EthAddr)
484			s.zki.Siblings2[s.i] = siblingsToZKInputFormat(p.Siblings)
485			// IsOld0_2, OldKey2, OldValue2 not needed as this is not an insert
486		}
487	}
488
489	return nil
490}
491
492// applyTransfer updates the balance & nonce in the account of the sender, and
493// the balance in the account of the receiver
494func (s *StateDB) applyTransfer(tx *common.Tx) error {
495	// get sender and receiver accounts from localStateDB
496	accSender, err := s.GetAccount(tx.FromIdx)
497	if err != nil {
498		return err
499	}
500	accReceiver, err := s.GetAccount(tx.ToIdx)
501	if err != nil {
502		return err
503	}
504
505	// increment nonce
506	accSender.Nonce++
507
508	// subtract amount to the sender
509	accSender.Balance = new(big.Int).Sub(accSender.Balance, tx.Amount)
510	// add amount to the receiver
511	accReceiver.Balance = new(big.Int).Add(accReceiver.Balance, tx.Amount)
512
513	// update sender account in localStateDB
514	pSender, err := s.UpdateAccount(tx.FromIdx, accSender)
515	if err != nil {
516		return err
517	}
518	if s.zki != nil {
519		s.zki.TokenID1[s.i] = accSender.TokenID.BigInt()
520		s.zki.Nonce1[s.i] = accSender.Nonce.BigInt()
521		if babyjub.PointCoordSign(accSender.PublicKey.X) {
522			s.zki.Sign1[s.i] = big.NewInt(1)
523		}
524		s.zki.Ay1[s.i] = accSender.PublicKey.Y
525		s.zki.Balance1[s.i] = accSender.Balance
526		s.zki.EthAddr1[s.i] = common.EthAddrToBigInt(accSender.EthAddr)
527		s.zki.Siblings1[s.i] = siblingsToZKInputFormat(pSender.Siblings)
528	}
529
530	// update receiver account in localStateDB
531	pReceiver, err := s.UpdateAccount(tx.ToIdx, accReceiver)
532	if err != nil {
533		return err
534	}
535	if s.zki != nil {
536		s.zki.TokenID2[s.i] = accReceiver.TokenID.BigInt()
537		s.zki.Nonce2[s.i] = accReceiver.Nonce.BigInt()
538		if babyjub.PointCoordSign(accReceiver.PublicKey.X) {
539			s.zki.Sign2[s.i] = big.NewInt(1)
540		}
541		s.zki.Ay2[s.i] = accReceiver.PublicKey.Y
542		s.zki.Balance2[s.i] = accReceiver.Balance
543		s.zki.EthAddr2[s.i] = common.EthAddrToBigInt(accReceiver.EthAddr)
544		s.zki.Siblings2[s.i] = siblingsToZKInputFormat(pReceiver.Siblings)
545	}
546
547	return nil
548}
549
550// applyCreateAccountDepositTransfer, in a single tx, creates a new account,
551// makes a deposit, and performs a transfer to another account
552func (s *StateDB) applyCreateAccountDepositTransfer(tx *common.L1Tx) error {
553	accSender := &common.Account{
554		TokenID:   tx.TokenID,
555		Nonce:     0,
556		Balance:   tx.LoadAmount,
557		PublicKey: tx.FromBJJ,
558		EthAddr:   tx.FromEthAddr,
559	}
560	accSender.Balance = new(big.Int).Add(accSender.Balance, tx.LoadAmount)
561	accReceiver, err := s.GetAccount(tx.ToIdx)
562	if err != nil {
563		return err
564	}
565	// subtract amount to the sender
566	accSender.Balance = new(big.Int).Sub(accSender.Balance, tx.Amount)
567	// add amount to the receiver
568	accReceiver.Balance = new(big.Int).Add(accReceiver.Balance, tx.Amount)
569
570	// create Account of the Sender
571	p, err := s.CreateAccount(common.Idx(s.idx+1), accSender)
572	if err != nil {
573		return err
574	}
575	if s.zki != nil {
576		s.zki.TokenID1[s.i] = tx.TokenID.BigInt()
577		s.zki.Nonce1[s.i] = big.NewInt(0)
578		if babyjub.PointCoordSign(tx.FromBJJ.X) {
579			s.zki.Sign1[s.i] = big.NewInt(1)
580		}
581		s.zki.Ay1[s.i] = tx.FromBJJ.Y
582		s.zki.Balance1[s.i] = tx.LoadAmount
583		s.zki.EthAddr1[s.i] = common.EthAddrToBigInt(tx.FromEthAddr)
584		s.zki.Siblings1[s.i] = siblingsToZKInputFormat(p.Siblings)
585		if p.IsOld0 {
586			s.zki.IsOld0_1[s.i] = big.NewInt(1)
587		}
588		s.zki.OldKey1[s.i] = p.OldKey.BigInt()
589		s.zki.OldValue1[s.i] = p.OldValue.BigInt()
590	}
591
592	// update receiver account in localStateDB
593	p, err = s.UpdateAccount(tx.ToIdx, accReceiver)
594	if err != nil {
595		return err
596	}
597	if s.zki != nil {
598		s.zki.TokenID2[s.i] = accReceiver.TokenID.BigInt()
599		s.zki.Nonce2[s.i] = accReceiver.Nonce.BigInt()
600		if babyjub.PointCoordSign(accReceiver.PublicKey.X) {
601			s.zki.Sign2[s.i] = big.NewInt(1)
602		}
603		s.zki.Ay2[s.i] = accReceiver.PublicKey.Y
604		s.zki.Balance2[s.i] = accReceiver.Balance
605		s.zki.EthAddr2[s.i] = common.EthAddrToBigInt(accReceiver.EthAddr)
606		s.zki.Siblings2[s.i] = siblingsToZKInputFormat(p.Siblings)
607	}
608
609	s.idx = s.idx + 1
610	return s.setIdx(s.idx)
611}
612
613// It returns the ExitAccount and a boolean determining if the Exit created a
614// new Leaf in the ExitTree.
615func (s *StateDB) applyExit(exitTree *merkletree.MerkleTree, tx *common.Tx) (*common.Account, bool, error) {
616	// 0. subtract tx.Amount from current Account in StateMT
617	// add the tx.Amount into the Account (tx.FromIdx) in the ExitMT
618	acc, err := s.GetAccount(tx.FromIdx)
619	if err != nil {
620		return nil, false, err
621	}
622	acc.Balance = new(big.Int).Sub(acc.Balance, tx.Amount)
623	p, err := s.UpdateAccount(tx.FromIdx, acc)
624	if err != nil {
625		return nil, false, err
626	}
627	if s.zki != nil {
628		s.zki.TokenID1[s.i] = acc.TokenID.BigInt()
629		s.zki.Nonce1[s.i] = acc.Nonce.BigInt()
630		if babyjub.PointCoordSign(acc.PublicKey.X) {
631			s.zki.Sign1[s.i] = big.NewInt(1)
632		}
633		s.zki.Ay1[s.i] = acc.PublicKey.Y
634		s.zki.Balance1[s.i] = acc.Balance
635		s.zki.EthAddr1[s.i] = common.EthAddrToBigInt(acc.EthAddr)
636		s.zki.Siblings1[s.i] = siblingsToZKInputFormat(p.Siblings)
637	}
638
639	if exitTree == nil {
640		return nil, false, nil
641	}
642	exitAccount, err := getAccountInTreeDB(exitTree.DB(), tx.FromIdx)
643	if err == db.ErrNotFound {
644		// 1a. if idx does not exist in exitTree:
645		// add new leaf 'ExitTreeLeaf', where ExitTreeLeaf.Balance = exitAmount (exitAmount=tx.Amount)
646		exitAccount := &common.Account{
647			TokenID:   acc.TokenID,
648			Nonce:     common.Nonce(1),
649			Balance:   tx.Amount,
650			PublicKey: acc.PublicKey,
651			EthAddr:   acc.EthAddr,
652		}
653		_, err = createAccountInTreeDB(exitTree.DB(), exitTree, tx.FromIdx, exitAccount)
654		return exitAccount, true, err
655	} else if err != nil {
656		return exitAccount, false, err
657	}
658
659	// 1b. if idx already exist in exitTree:
660	// update account, where account.Balance += exitAmount
661	exitAccount.Balance = new(big.Int).Add(exitAccount.Balance, tx.Amount)
662	_, err = updateAccountInTreeDB(exitTree.DB(), exitTree, tx.FromIdx, exitAccount)
663	return exitAccount, false, err
664}
665
666// getIdx returns the stored Idx from the localStateDB, which is the last Idx
667// used for an Account in the localStateDB.
668func (s *StateDB) getIdx() (common.Idx, error) {
669	idxBytes, err := s.DB().Get(keyidx)
670	if err == db.ErrNotFound {
671		return 0, nil
672	}
673	if err != nil {
674		return 0, err
675	}
676	return common.IdxFromBytes(idxBytes[:4])
677}
678
679// setIdx stores Idx in the localStateDB
680func (s *StateDB) setIdx(idx common.Idx) error {
681	tx, err := s.DB().NewTx()
682	if err != nil {
683		return err
684	}
685	err = tx.Put(keyidx, idx.Bytes())
686	if err != nil {
687		return err
688	}
689	if err := tx.Commit(); err != nil {
690		return err
691	}
692	return nil
693}