protocol/validation/vmcontext.go

   1 package validation
   2
   3 import (
   4         "bytes"
   5
   6         "github.com/vapor/consensus/segwit"
   7         "github.com/vapor/crypto/sha3pool"
   8         "github.com/vapor/errors"
   9         "github.com/vapor/protocol/bc"
  10         "github.com/vapor/protocol/vm"
  11 )
  12
  13 // NewTxVMContext generates the vm.Context for BVM
  14 func NewTxVMContext(vs *validationState, entry bc.Entry, prog *bc.Program, args [][]byte) *vm.Context {
  15         var (
  16                 tx          = vs.tx
  17                 blockHeight = vs.block.BlockHeader.GetHeight()
  18                 numResults  = uint64(len(tx.ResultIds))
  19                 entryID     = bc.EntryID(entry) // TODO(bobg): pass this in, don't recompute it
  20
  21                 assetID       *[]byte
  22                 amount        *uint64
  23                 destPos       *uint64
  24                 spentOutputID *[]byte
  25         )
  26
  27         switch e := entry.(type) {
  28         case *bc.Issuance:
  29                 a1 := e.Value.AssetId.Bytes()
  30                 assetID = &a1
  31                 amount = &e.Value.Amount
  32                 destPos = &e.WitnessDestination.Position
  33
  34         case *bc.Spend:
  35                 spentOutput := tx.Entries[*e.SpentOutputId].(*bc.Output)
  36                 a1 := spentOutput.Source.Value.AssetId.Bytes()
  37                 assetID = &a1
  38                 amount = &spentOutput.Source.Value.Amount
  39                 destPos = &e.WitnessDestination.Position
  40                 s := e.SpentOutputId.Bytes()
  41                 spentOutputID = &s
  42         }
  43
  44         var txSigHash *[]byte
  45         txSigHashFn := func() []byte {
  46                 if txSigHash == nil {
  47                         hasher := sha3pool.Get256()
  48                         defer sha3pool.Put256(hasher)
  49
  50                         entryID.WriteTo(hasher)
  51                         tx.ID.WriteTo(hasher)
  52
  53                         var hash bc.Hash
  54                         hash.ReadFrom(hasher)
  55                         hashBytes := hash.Bytes()
  56                         txSigHash = &hashBytes
  57                 }
  58                 return *txSigHash
  59         }
  60
  61         ec := &entryContext{
  62                 entry:   entry,
  63                 entries: tx.Entries,
  64         }
  65
  66         result := &vm.Context{
  67                 VMVersion: prog.VmVersion,
  68                 Code:      witnessProgram(prog.Code),
  69                 Arguments: args,
  70
  71                 EntryID: entryID.Bytes(),
  72
  73                 TxVersion:   &tx.Version,
  74                 BlockHeight: &blockHeight,
  75
  76                 TxSigHash:     txSigHashFn,
  77                 NumResults:    &numResults,
  78                 AssetID:       assetID,
  79                 Amount:        amount,
  80                 DestPos:       destPos,
  81                 SpentOutputID: spentOutputID,
  82                 CheckOutput:   ec.checkOutput,
  83         }
  84
  85         return result
  86 }
  87
  88 func witnessProgram(prog []byte) []byte {
  89         if segwit.IsP2WPKHScript(prog) {
  90                 if witnessProg, err := segwit.ConvertP2PKHSigProgram([]byte(prog)); err == nil {
  91                         return witnessProg
  92                 }
  93         } else if segwit.IsP2WSHScript(prog) {
  94                 if witnessProg, err := segwit.ConvertP2SHProgram([]byte(prog)); err == nil {
  95                         return witnessProg
  96                 }
  97         }
  98         return prog
  99 }
 100
 101 type entryContext struct {
 102         entry   bc.Entry
 103         entries map[bc.Hash]bc.Entry
 104 }
 105
 106 func (ec *entryContext) checkOutput(index uint64, amount uint64, assetID []byte, vmVersion uint64, code []byte, expansion bool) (bool, error) {
 107         checkEntry := func(e bc.Entry) (bool, error) {
 108                 check := func(prog *bc.Program, value *bc.AssetAmount) bool {
 109                         return (prog.VmVersion == vmVersion &&
 110                                 bytes.Equal(prog.Code, code) &&
 111                                 bytes.Equal(value.AssetId.Bytes(), assetID) &&
 112                                 value.Amount == amount)
 113                 }
 114
 115                 switch e := e.(type) {
 116                 case *bc.Output:
 117                         return check(e.ControlProgram, e.Source.Value), nil
 118
 119                 case *bc.Retirement:
 120                         var prog bc.Program
 121                         if expansion {
 122                                 // The spec requires prog.Code to be the empty string only
 123                                 // when !expansion. When expansion is true, we prepopulate
 124                                 // prog.Code to give check() a freebie match.
 125                                 //
 126                                 // (The spec always requires prog.VmVersion to be zero.)
 127                                 prog.Code = code
 128                         }
 129                         return check(&prog, e.Source.Value), nil
 130                 }
 131
 132                 return false, vm.ErrContext
 133         }
 134
 135         checkMux := func(m *bc.Mux) (bool, error) {
 136                 if index >= uint64(len(m.WitnessDestinations)) {
 137                         return false, errors.Wrapf(vm.ErrBadValue, "index %d >= %d", index, len(m.WitnessDestinations))
 138                 }
 139                 eID := m.WitnessDestinations[index].Ref
 140                 e, ok := ec.entries[*eID]
 141                 if !ok {
 142                         return false, errors.Wrapf(bc.ErrMissingEntry, "entry for mux destination %d, id %x, not found", index, eID.Bytes())
 143                 }
 144                 return checkEntry(e)
 145         }
 146
 147         switch e := ec.entry.(type) {
 148         case *bc.Mux:
 149                 return checkMux(e)
 150
 151         case *bc.Issuance:
 152                 d, ok := ec.entries[*e.WitnessDestination.Ref]
 153                 if !ok {
 154                         return false, errors.Wrapf(bc.ErrMissingEntry, "entry for issuance destination %x not found", e.WitnessDestination.Ref.Bytes())
 155                 }
 156                 if m, ok := d.(*bc.Mux); ok {
 157                         return checkMux(m)
 158                 }
 159                 if index != 0 {
 160                         return false, errors.Wrapf(vm.ErrBadValue, "index %d >= 1", index)
 161                 }
 162                 return checkEntry(d)
 163
 164         case *bc.Spend:
 165                 d, ok := ec.entries[*e.WitnessDestination.Ref]
 166                 if !ok {
 167                         return false, errors.Wrapf(bc.ErrMissingEntry, "entry for spend destination %x not found", e.WitnessDestination.Ref.Bytes())
 168                 }
 169                 if m, ok := d.(*bc.Mux); ok {
 170                         return checkMux(m)
 171                 }
 172                 if index != 0 {
 173                         return false, errors.Wrapf(vm.ErrBadValue, "index %d >= 1", index)
 174                 }
 175                 return checkEntry(d)
 176         }
 177
 178         return false, vm.ErrContext
 179 }