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.CrossChainInput:
  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                 switch spentOutput := tx.Entries[*e.SpentOutputId].(type) {
  36                 case *bc.IntraChainOutput:
  37                         a1 := spentOutput.Source.Value.AssetId.Bytes()
  38                         assetID = &a1
  39                         amount = &spentOutput.Source.Value.Amount
  40                         destPos = &e.WitnessDestination.Position
  41                         s := e.SpentOutputId.Bytes()
  42                         spentOutputID = &s
  43
  44                 case *bc.VoteOutput:
  45                         a1 := spentOutput.Source.Value.AssetId.Bytes()
  46                         assetID = &a1
  47                         amount = &spentOutput.Source.Value.Amount
  48                         destPos = &e.WitnessDestination.Position
  49                         s := e.SpentOutputId.Bytes()
  50                         spentOutputID = &s
  51                 }
  52         }
  53
  54         var txSigHash *[]byte
  55         txSigHashFn := func() []byte {
  56                 if txSigHash == nil {
  57                         hasher := sha3pool.Get256()
  58                         defer sha3pool.Put256(hasher)
  59
  60                         entryID.WriteTo(hasher)
  61                         tx.ID.WriteTo(hasher)
  62
  63                         var hash bc.Hash
  64                         hash.ReadFrom(hasher)
  65                         hashBytes := hash.Bytes()
  66                         txSigHash = &hashBytes
  67                 }
  68                 return *txSigHash
  69         }
  70
  71         ec := &entryContext{
  72                 entry:   entry,
  73                 entries: tx.Entries,
  74         }
  75
  76         result := &vm.Context{
  77                 VMVersion: prog.VmVersion,
  78                 Code:      witnessProgram(prog.Code),
  79                 Arguments: args,
  80
  81                 EntryID: entryID.Bytes(),
  82
  83                 TxVersion:   &tx.Version,
  84                 BlockHeight: &blockHeight,
  85
  86                 TxSigHash:     txSigHashFn,
  87                 NumResults:    &numResults,
  88                 AssetID:       assetID,
  89                 Amount:        amount,
  90                 DestPos:       destPos,
  91                 SpentOutputID: spentOutputID,
  92                 CheckOutput:   ec.checkOutput,
  93         }
  94
  95         return result
  96 }
  97
  98 func witnessProgram(prog []byte) []byte {
  99         if segwit.IsP2WPKHScript(prog) {
 100                 if witnessProg, err := segwit.ConvertP2PKHSigProgram([]byte(prog)); err == nil {
 101                         return witnessProg
 102                 }
 103         } else if segwit.IsP2WSHScript(prog) {
 104                 if witnessProg, err := segwit.ConvertP2SHProgram([]byte(prog)); err == nil {
 105                         return witnessProg
 106                 }
 107         }
 108         return prog
 109 }
 110
 111 type entryContext struct {
 112         entry   bc.Entry
 113         entries map[bc.Hash]bc.Entry
 114 }
 115
 116 func (ec *entryContext) checkOutput(index uint64, amount uint64, assetID []byte, vmVersion uint64, code []byte, expansion bool) (bool, error) {
 117         checkEntry := func(e bc.Entry) (bool, error) {
 118                 check := func(prog *bc.Program, value *bc.AssetAmount) bool {
 119                         return (prog.VmVersion == vmVersion &&
 120                                 bytes.Equal(prog.Code, code) &&
 121                                 bytes.Equal(value.AssetId.Bytes(), assetID) &&
 122                                 value.Amount == amount)
 123                 }
 124
 125                 switch e := e.(type) {
 126                 case *bc.IntraChainOutput:
 127                         return check(e.ControlProgram, e.Source.Value), nil
 128
 129                 case *bc.VoteOutput:
 130                         return check(e.ControlProgram, e.Source.Value), nil
 131
 132                 case *bc.Retirement:
 133                         var prog bc.Program
 134                         if expansion {
 135                                 // The spec requires prog.Code to be the empty string only
 136                                 // when !expansion. When expansion is true, we prepopulate
 137                                 // prog.Code to give check() a freebie match.
 138                                 //
 139                                 // (The spec always requires prog.VmVersion to be zero.)
 140                                 prog.Code = code
 141                         }
 142                         return check(&prog, e.Source.Value), nil
 143                 }
 144
 145                 return false, vm.ErrContext
 146         }
 147
 148         checkMux := func(m *bc.Mux) (bool, error) {
 149                 if index >= uint64(len(m.WitnessDestinations)) {
 150                         return false, errors.Wrapf(vm.ErrBadValue, "index %d >= %d", index, len(m.WitnessDestinations))
 151                 }
 152                 eID := m.WitnessDestinations[index].Ref
 153                 e, ok := ec.entries[*eID]
 154                 if !ok {
 155                         return false, errors.Wrapf(bc.ErrMissingEntry, "entry for mux destination %d, id %x, not found", index, eID.Bytes())
 156                 }
 157                 return checkEntry(e)
 158         }
 159
 160         switch e := ec.entry.(type) {
 161         case *bc.Mux:
 162                 return checkMux(e)
 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 }