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https://github.com/aljazceru/ark.git
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Congestion tree validation (#84)
* add common/pkg/tree validation * update noah go.mod * cleaning and fixes * fix builder_test.go * Fix deferred func * fix even number of vtxos in congestion tree --------- Co-authored-by: altafan <18440657+altafan@users.noreply.github.com>
This commit is contained in:
Louis Singer
306
common/tree/validation.go
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306
common/tree/validation.go
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@@ -0,0 +1,306 @@
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package tree
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import (
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"bytes"
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"encoding/hex"
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"errors"
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"fmt"
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"github.com/btcsuite/btcd/btcec/v2/schnorr"
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"github.com/btcsuite/btcd/chaincfg/chainhash"
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"github.com/decred/dcrd/dcrec/secp256k1/v4"
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"github.com/vulpemventures/go-elements/elementsutil"
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"github.com/vulpemventures/go-elements/psetv2"
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"github.com/vulpemventures/go-elements/taproot"
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"github.com/vulpemventures/go-elements/transaction"
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)
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var (
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ErrInvalidPoolTransaction = errors.New("invalid pool transaction")
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ErrEmptyTree = errors.New("empty congestion tree")
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ErrInvalidRootLevel = errors.New("root level must have only one node")
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ErrNoLeaves = errors.New("no leaves in the tree")
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ErrNodeTransactionEmpty = errors.New("node transaction is empty")
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ErrNodeTxidEmpty = errors.New("node txid is empty")
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ErrNodeParentTxidEmpty = errors.New("node parent txid is empty")
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ErrNodeTxidDifferent = errors.New("node txid differs from node transaction")
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ErrNumberOfInputs = errors.New("node transaction should have only one input")
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ErrNumberOfOutputs = errors.New("node transaction should have only three or two outputs")
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ErrParentTxidInput = errors.New("parent txid should be the input of the node transaction")
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ErrNumberOfChildren = errors.New("node branch transaction should have two children")
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ErrLeafChildren = errors.New("leaf node should have max 1 child")
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ErrInvalidChildTxid = errors.New("invalid child txid")
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ErrNumberOfTapscripts = errors.New("input should have two tapscripts leaves")
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ErrInternalKey = errors.New("taproot internal key is not unspendable")
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ErrInvalidTaprootScript = errors.New("invalid taproot script")
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ErrInvalidLeafTaprootScript = errors.New("invalid leaf taproot script")
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ErrInvalidAmount = errors.New("children amount is different from parent amount")
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ErrInvalidAsset = errors.New("invalid output asset")
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ErrInvalidSweepSequence = errors.New("invalid sweep sequence")
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ErrInvalidASP = errors.New("invalid ASP")
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ErrMissingFeeOutput = errors.New("missing fee output")
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ErrInvalidLeftOutput = errors.New("invalid left output")
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ErrInvalidRightOutput = errors.New("invalid right output")
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ErrMissingSweepTapscript = errors.New("missing sweep tapscript")
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ErrMissingBranchTapscript = errors.New("missing branch tapscript")
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ErrInvalidLeaf = errors.New("leaf node shouldn't have children")
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ErrWrongPoolTxID = errors.New("root input should be the pool tx outpoint")
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)
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const (
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UnspendablePoint = "0250929b74c1a04954b78b4b6035e97a5e078a5a0f28ec96d547bfee9ace803ac0"
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sharedOutputIndex = 0
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)
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// ValidateCongestionTree checks if the given congestion tree is valid
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// poolTxID & poolTxIndex & poolTxAmount are used to validate the root input outpoint
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// aspPublicKey & roundLifetimeSeconds are used to validate the sweep tapscript leaves
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// besides that, the function validates:
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// - the number of nodes
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// - the number of leaves
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// - children coherence with parent
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// - every control block and taproot output scripts
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// - input and output amounts
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func ValidateCongestionTree(
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tree CongestionTree,
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poolTxHex string,
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aspPublicKey *secp256k1.PublicKey,
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roundLifetimeSeconds uint,
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) error {
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unspendableKeyBytes, _ := hex.DecodeString(UnspendablePoint)
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unspendableKey, _ := secp256k1.ParsePubKey(unspendableKeyBytes)
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poolTransaction, err := transaction.NewTxFromHex(poolTxHex)
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if err != nil {
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return ErrInvalidPoolTransaction
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}
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poolTxAmount, err := elementsutil.ValueFromBytes(poolTransaction.Outputs[sharedOutputIndex].Value)
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if err != nil {
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return ErrInvalidPoolTransaction
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}
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poolTxID := poolTransaction.TxHash().String()
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nbNodes := tree.NumberOfNodes()
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if nbNodes == 0 {
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return ErrEmptyTree
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}
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if len(tree[0]) != 1 {
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return ErrInvalidRootLevel
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}
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// check that root input is connected to the pool tx
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rootPsetB64 := tree[0][0].Tx
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rootPset, err := psetv2.NewPsetFromBase64(rootPsetB64)
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if err != nil {
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return fmt.Errorf("invalid root transaction: %w", err)
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}
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if len(rootPset.Inputs) != 1 {
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return ErrNumberOfInputs
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}
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rootInput := rootPset.Inputs[0]
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if chainhash.Hash(rootInput.PreviousTxid).String() != poolTxID || rootInput.PreviousTxIndex != sharedOutputIndex {
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return ErrWrongPoolTxID
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}
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sumRootValue := uint64(0)
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for _, output := range rootPset.Outputs {
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sumRootValue += output.Value
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}
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if sumRootValue != poolTxAmount {
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return ErrInvalidAmount
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}
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if len(tree.Leaves()) == 0 {
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return ErrNoLeaves
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}
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// iterates over all the nodes of the tree
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for _, level := range tree {
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for _, node := range level {
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if err := validateNodeTransaction(node, tree, unspendableKey, aspPublicKey, roundLifetimeSeconds); err != nil {
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return err
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}
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}
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}
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return nil
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}
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func validateNodeTransaction(
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node Node,
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tree CongestionTree,
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expectedInternalKey,
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expectedPublicKeyASP *secp256k1.PublicKey,
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expectedSequenceSeconds uint,
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) error {
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if node.Tx == "" {
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return ErrNodeTransactionEmpty
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}
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if node.Txid == "" {
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return ErrNodeTxidEmpty
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}
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if node.ParentTxid == "" {
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return ErrNodeParentTxidEmpty
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}
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decodedPset, err := psetv2.NewPsetFromBase64(node.Tx)
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if err != nil {
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return fmt.Errorf("invalid node transaction: %w", err)
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}
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utx, err := decodedPset.UnsignedTx()
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if err != nil {
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return fmt.Errorf("invalid node transaction: %w", err)
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}
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if utx.TxHash().String() != node.Txid {
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return ErrNodeTxidDifferent
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}
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if len(decodedPset.Inputs) != 1 {
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return ErrNumberOfInputs
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}
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input := decodedPset.Inputs[0]
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if len(input.TapLeafScript) != 2 {
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return ErrNumberOfTapscripts
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}
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if chainhash.Hash(decodedPset.Inputs[0].PreviousTxid).String() != node.ParentTxid {
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return ErrParentTxidInput
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}
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feeOutput := decodedPset.Outputs[len(decodedPset.Outputs)-1]
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if len(feeOutput.Script) != 0 {
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return ErrMissingFeeOutput
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}
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children := tree.Children(node.Txid)
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if node.Leaf && len(children) > 1 {
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return ErrLeafChildren
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}
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for childIndex, child := range children {
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childTx, err := psetv2.NewPsetFromBase64(child.Tx)
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if err != nil {
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return fmt.Errorf("invalid child transaction: %w", err)
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}
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parentOutput := decodedPset.Outputs[childIndex]
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previousScriptKey := parentOutput.Script[2:]
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if len(previousScriptKey) != 32 {
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return ErrInvalidTaprootScript
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}
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sweepLeafFound := false
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branchLeafFound := false
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for _, tapLeaf := range childTx.Inputs[0].TapLeafScript {
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key := tapLeaf.ControlBlock.InternalKey
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if !key.IsEqual(expectedInternalKey) {
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return ErrInternalKey
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}
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rootHash := tapLeaf.ControlBlock.RootHash(tapLeaf.Script)
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outputScript := taproot.ComputeTaprootOutputKey(key, rootHash)
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if !bytes.Equal(schnorr.SerializePubKey(outputScript), previousScriptKey) {
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return ErrInvalidTaprootScript
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}
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isSweepLeaf, aspKey, seconds, err := decodeSweepScript(tapLeaf.Script)
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if err != nil {
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return fmt.Errorf("invalid sweep script: %w", err)
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}
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if isSweepLeaf {
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if !aspKey.IsEqual(aspKey) {
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return ErrInvalidASP
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}
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if seconds != expectedSequenceSeconds {
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return ErrInvalidSweepSequence
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}
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sweepLeafFound = true
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continue
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}
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isBranchLeaf, leftKey, rightKey, leftAmount, rightAmount, err := decodeBranchScript(tapLeaf.Script)
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if err != nil {
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return fmt.Errorf("invalid vtxo script: %w", err)
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}
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if isBranchLeaf {
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branchLeafFound = true
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// check outputs
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nbOuts := len(childTx.Outputs)
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if leftKey != nil && rightKey != nil {
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if nbOuts != 3 {
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return ErrNumberOfOutputs
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}
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} else {
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if nbOuts != 2 {
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return ErrNumberOfOutputs
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}
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}
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leftWitnessProgram := childTx.Outputs[0].Script[2:]
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leftOutputAmount := childTx.Outputs[0].Value
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if !bytes.Equal(leftWitnessProgram, schnorr.SerializePubKey(leftKey)) {
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return ErrInvalidLeftOutput
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}
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if leftAmount != leftOutputAmount {
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return ErrInvalidLeftOutput
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}
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if rightKey != nil {
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rightWitnessProgram := childTx.Outputs[1].Script[2:]
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rightOutputAmount := childTx.Outputs[1].Value
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if !bytes.Equal(rightWitnessProgram, schnorr.SerializePubKey(rightKey)) {
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return ErrInvalidRightOutput
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}
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if rightAmount != rightOutputAmount {
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return ErrInvalidRightOutput
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}
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}
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}
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}
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if !sweepLeafFound {
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return ErrMissingSweepTapscript
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}
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if !branchLeafFound {
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return ErrMissingBranchTapscript
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}
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sumChildAmount := uint64(0)
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for _, output := range childTx.Outputs {
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sumChildAmount += output.Value
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if !bytes.Equal(output.Asset, parentOutput.Asset) {
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return ErrInvalidAsset
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}
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}
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if sumChildAmount != parentOutput.Value {
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return ErrInvalidAmount
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}
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}
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return nil
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}
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