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additional checks, simplifications
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Since lightwalletd only works with Sapling and beyond, and since Sapling
requires v4 transactions, there's no need to distinguish between pre-v4
and v4 (we will never see pre-v4). This simplifies some of the
conditionals.

Also, add some additional checks, such as version group ID and consensus
branch ID.
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Larry Ruane committed Oct 18, 2021
1 parent 25949b2 commit 6f019a3
Showing 1 changed file with 55 additions and 58 deletions.
113 changes: 55 additions & 58 deletions parser/transaction.go
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Original file line number Diff line number Diff line change
Expand Up @@ -361,10 +361,13 @@ func (tx *Transaction) ToCompact(index int) *walletrpc.CompactTx {
return ctx
}

// parse versions 2 through 4
func (tx *Transaction) parseV1to4(data []byte, version uint32) ([]byte, error) {
// parse version 4
func (tx *Transaction) parseV4(data []byte) ([]byte, error) {
s := bytestring.String(data)
var err error
if tx.nVersionGroupID != 0x892F2085 {
return nil, errors.New(fmt.Sprintf("version group ID %x must be 0x892F2085", tx.nVersionGroupID))
}
s, err = tx.ParseTransparent([]byte(s))
if err != nil {
return nil, err
Expand All @@ -373,45 +376,41 @@ func (tx *Transaction) parseV1to4(data []byte, version uint32) ([]byte, error) {
return nil, errors.New("could not read nLockTime")
}

if tx.fOverwintered {
if !s.ReadUint32(&tx.nExpiryHeight) {
return nil, errors.New("could not read nExpiryHeight")
}
if !s.ReadUint32(&tx.nExpiryHeight) {
return nil, errors.New("could not read nExpiryHeight")
}

var spendCount, outputCount int

if tx.version >= 4 {
if !s.ReadInt64(&tx.valueBalanceSapling) {
return nil, errors.New("could not read valueBalance")
}
if !s.ReadCompactSize(&spendCount) {
return nil, errors.New("could not read nShieldedSpend")
}
if spendCount > 0 {
tx.shieldedSpends = make([]*spend, spendCount)
for i := 0; i < spendCount; i++ {
newSpend := &spend{}
s, err = newSpend.ParseFromSlice([]byte(s), tx.version)
if err != nil {
return nil, errors.Wrap(err, "while parsing shielded Spend")
}
tx.shieldedSpends[i] = newSpend
if !s.ReadInt64(&tx.valueBalanceSapling) {
return nil, errors.New("could not read valueBalance")
}
if !s.ReadCompactSize(&spendCount) {
return nil, errors.New("could not read nShieldedSpend")
}
if spendCount > 0 {
tx.shieldedSpends = make([]*spend, spendCount)
for i := 0; i < spendCount; i++ {
newSpend := &spend{}
s, err = newSpend.ParseFromSlice([]byte(s), 4)
if err != nil {
return nil, errors.Wrap(err, "while parsing shielded Spend")
}
tx.shieldedSpends[i] = newSpend
}
if !s.ReadCompactSize(&outputCount) {
return nil, errors.New("could not read nShieldedOutput")
}
if outputCount > 0 {
tx.shieldedOutputs = make([]*output, outputCount)
for i := 0; i < outputCount; i++ {
newOutput := &output{}
s, err = newOutput.ParseFromSlice([]byte(s), tx.version)
if err != nil {
return nil, errors.Wrap(err, "while parsing shielded Output")
}
tx.shieldedOutputs[i] = newOutput
}
if !s.ReadCompactSize(&outputCount) {
return nil, errors.New("could not read nShieldedOutput")
}
if outputCount > 0 {
tx.shieldedOutputs = make([]*output, outputCount)
for i := 0; i < outputCount; i++ {
newOutput := &output{}
s, err = newOutput.ParseFromSlice([]byte(s), 4)
if err != nil {
return nil, errors.Wrap(err, "while parsing shielded Output")
}
tx.shieldedOutputs[i] = newOutput
}
}
var joinSplitCount int
Expand All @@ -422,7 +421,7 @@ func (tx *Transaction) parseV1to4(data []byte, version uint32) ([]byte, error) {
if joinSplitCount > 0 {
tx.joinSplits = make([]*joinSplit, joinSplitCount)
for i := 0; i < joinSplitCount; i++ {
js := &joinSplit{version: tx.version}
js := &joinSplit{version: 4}
s, err = js.ParseFromSlice([]byte(s))
if err != nil {
return nil, errors.Wrap(err, "while parsing JoinSplit")
Expand All @@ -438,21 +437,25 @@ func (tx *Transaction) parseV1to4(data []byte, version uint32) ([]byte, error) {
return nil, errors.New("could not read joinSplitSig")
}
}
if tx.version >= 4 {
if spendCount+outputCount > 0 && !s.ReadBytes(&tx.bindingSigSapling, 64) {
return nil, errors.New("could not read bindingSigSapling")
}
if spendCount+outputCount > 0 && !s.ReadBytes(&tx.bindingSigSapling, 64) {
return nil, errors.New("could not read bindingSigSapling")
}
return s, nil
}

// parse version 5
func (tx *Transaction) parseV5(data []byte, version uint32) ([]byte, error) {
func (tx *Transaction) parseV5(data []byte) ([]byte, error) {
s := bytestring.String(data)
var err error
if !s.ReadUint32(&tx.consensusBranchID) {
return nil, errors.New("could not read nVersionGroupId")
}
if tx.nVersionGroupID != 0x26A7270A {
return nil, errors.New(fmt.Sprintf("version number %d must be 0x26A7270A", tx.nVersionGroupID))
}
if tx.consensusBranchID != 0x37519621 {
return nil, errors.New("unknown consensusBranchID")
}
if !s.ReadUint32(&tx.nLockTime) {
return nil, errors.New("could not read nLockTime")
}
Expand Down Expand Up @@ -511,6 +514,9 @@ func (tx *Transaction) parseV5(data []byte, version uint32) ([]byte, error) {
if !s.ReadCompactSize(&actionsCount) {
return nil, errors.New("could not read nActionsOrchard")
}
if actionsCount >= (1 << 16) {
return nil, errors.New(fmt.Sprintf("actionsCount (%d) must be less than 2^16", actionsCount))
}
if !s.Skip(820 * actionsCount) {
return nil, errors.New("could not skip vActionsOrchard")
}
Expand Down Expand Up @@ -554,31 +560,22 @@ func (tx *Transaction) ParseFromSlice(data []byte) ([]byte, error) {
}

tx.fOverwintered = (header >> 31) == 1
tx.version = header & 0x7FFFFFFF

// Implement the effective version rule. From the spec section 7.1:
//
// "Version constraints apply to the effectiveVersion, which is equal to
// min(2, version) when fOverwintered = 0 and to version otherwise."
if !tx.fOverwintered && tx.version > 2 {
tx.version = 2
if !tx.fOverwintered {
return nil, errors.New("fOverwinter flag must be set")
}

// Spec says fOverwinter must be set for version 5.
if tx.version >= 5 && !tx.fOverwintered {
return nil, errors.New(fmt.Sprintf("version %d requires fOverwinter", tx.version))
tx.version = header & 0x7FFFFFFF
if tx.version < 4 {
return nil, errors.New(fmt.Sprintf("version number %d must be greater or equal to 4", tx.version))
}

if tx.version >= 3 {
if !s.ReadUint32(&tx.nVersionGroupID) {
return nil, errors.New("could not read nVersionGroupId")
}
if !s.ReadUint32(&tx.nVersionGroupID) {
return nil, errors.New("could not read nVersionGroupId")
}
// parse the main part of the transaction
if tx.version <= 4 {
s, err = tx.parseV1to4([]byte(s), tx.version)
s, err = tx.parseV4([]byte(s))
} else {
s, err = tx.parseV5([]byte(s), tx.version)
s, err = tx.parseV5([]byte(s))
}
if err != nil {
return nil, err
Expand Down

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