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134 lines
3.8 KiB
134 lines
3.8 KiB
package merkle
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import (
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"bytes"
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cmn "github.com/tendermint/tendermint/libs/common"
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)
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//----------------------------------------
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// ProofOp gets converted to an instance of ProofOperator:
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// ProofOperator is a layer for calculating intermediate Merkle roots
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// when a series of Merkle trees are chained together.
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// Run() takes leaf values from a tree and returns the Merkle
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// root for the corresponding tree. It takes and returns a list of bytes
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// to allow multiple leaves to be part of a single proof, for instance in a range proof.
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// ProofOp() encodes the ProofOperator in a generic way so it can later be
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// decoded with OpDecoder.
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type ProofOperator interface {
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Run([][]byte) ([][]byte, error)
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GetKey() []byte
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ProofOp() ProofOp
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}
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//----------------------------------------
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// Operations on a list of ProofOperators
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// ProofOperators is a slice of ProofOperator(s).
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// Each operator will be applied to the input value sequentially
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// and the last Merkle root will be verified with already known data
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type ProofOperators []ProofOperator
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func (poz ProofOperators) VerifyValue(root []byte, keypath string, value []byte) (err error) {
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return poz.Verify(root, keypath, [][]byte{value})
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}
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func (poz ProofOperators) Verify(root []byte, keypath string, args [][]byte) (err error) {
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keys, err := KeyPathToKeys(keypath)
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if err != nil {
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return
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}
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for i, op := range poz {
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key := op.GetKey()
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if len(key) != 0 {
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if !bytes.Equal(keys[0], key) {
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return cmn.NewError("Key mismatch on operation #%d: expected %+v but %+v", i, []byte(keys[0]), []byte(key))
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}
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keys = keys[1:]
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}
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args, err = op.Run(args)
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if err != nil {
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return
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}
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}
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if !bytes.Equal(root, args[0]) {
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return cmn.NewError("Calculated root hash is invalid: expected %+v but %+v", root, args[0])
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}
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if len(keys) != 0 {
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return cmn.NewError("Keypath not consumed all")
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}
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return nil
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}
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//----------------------------------------
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// ProofRuntime - main entrypoint
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type OpDecoder func(ProofOp) (ProofOperator, error)
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type ProofRuntime struct {
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decoders map[string]OpDecoder
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}
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func NewProofRuntime() *ProofRuntime {
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return &ProofRuntime{
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decoders: make(map[string]OpDecoder),
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}
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}
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func (prt *ProofRuntime) RegisterOpDecoder(typ string, dec OpDecoder) {
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_, ok := prt.decoders[typ]
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if ok {
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panic("already registered for type " + typ)
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}
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prt.decoders[typ] = dec
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}
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func (prt *ProofRuntime) Decode(pop ProofOp) (ProofOperator, error) {
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decoder := prt.decoders[pop.Type]
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if decoder == nil {
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return nil, cmn.NewError("unrecognized proof type %v", pop.Type)
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}
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return decoder(pop)
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}
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func (prt *ProofRuntime) DecodeProof(proof *Proof) (ProofOperators, error) {
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var poz ProofOperators
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for _, pop := range proof.Ops {
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operator, err := prt.Decode(pop)
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if err != nil {
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return nil, cmn.ErrorWrap(err, "decoding a proof operator")
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}
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poz = append(poz, operator)
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}
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return poz, nil
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}
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func (prt *ProofRuntime) VerifyValue(proof *Proof, root []byte, keypath string, value []byte) (err error) {
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return prt.Verify(proof, root, keypath, [][]byte{value})
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}
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// TODO In the long run we'll need a method of classifcation of ops,
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// whether existence or absence or perhaps a third?
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func (prt *ProofRuntime) VerifyAbsence(proof *Proof, root []byte, keypath string) (err error) {
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return prt.Verify(proof, root, keypath, nil)
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}
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func (prt *ProofRuntime) Verify(proof *Proof, root []byte, keypath string, args [][]byte) (err error) {
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poz, err := prt.DecodeProof(proof)
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if err != nil {
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return cmn.ErrorWrap(err, "decoding proof")
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}
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return poz.Verify(root, keypath, args)
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}
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// DefaultProofRuntime only knows about Simple value
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// proofs.
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// To use e.g. IAVL proofs, register op-decoders as
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// defined in the IAVL package.
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func DefaultProofRuntime() (prt *ProofRuntime) {
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prt = NewProofRuntime()
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prt.RegisterOpDecoder(ProofOpSimpleValue, SimpleValueOpDecoder)
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return
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}
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