github.com/kchristidis/fabric@v1.0.4-0.20171028114726-837acd08cde1/examples/chaincode/go/utxo/util/utxo.go (about)

     1  /*
     2  Copyright IBM Corp. 2016 All Rights Reserved.
     3  
     4  Licensed under the Apache License, Version 2.0 (the "License");
     5  you may not use this file except in compliance with the License.
     6  You may obtain a copy of the License at
     7  
     8  		 http://www.apache.org/licenses/LICENSE-2.0
     9  
    10  Unless required by applicable law or agreed to in writing, software
    11  distributed under the License is distributed on an "AS IS" BASIS,
    12  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    13  See the License for the specific language governing permissions and
    14  limitations under the License.
    15  */
    16  
    17  package util
    18  
    19  import (
    20  	"crypto/sha256"
    21  	"encoding/hex"
    22  	"fmt"
    23  	"math"
    24  
    25  	"github.com/hyperledger/fabric/examples/chaincode/go/utxo/consensus"
    26  )
    27  
    28  // UTXO includes the storage for the chaincode API or an in memory
    29  // store for testing
    30  type UTXO struct {
    31  	Store Store
    32  }
    33  
    34  // MakeUTXO constructs a new UTXO with the given store
    35  func MakeUTXO(store Store) *UTXO {
    36  	utxo := &UTXO{}
    37  	utxo.Store = store
    38  	return utxo
    39  }
    40  
    41  // Key represents the key for a transaction in storage. It has both a
    42  // hash and index
    43  type Key struct {
    44  	TxHashAsHex string
    45  	TxIndex     uint32
    46  }
    47  
    48  // GetTransactionHash returns the Bitcoin hash (double sha256) of
    49  // the given transaction
    50  func (u *UTXO) GetTransactionHash(txData []byte) [32]byte {
    51  	firstHash := sha256.Sum256(txData)
    52  	txHash := sha256.Sum256(firstHash[:])
    53  	return txHash
    54  }
    55  
    56  // IsCoinbase returns true if this is a coinbase transaction, false otherwise
    57  func (u *UTXO) IsCoinbase(index uint32) bool {
    58  	return index == math.MaxUint32
    59  }
    60  
    61  var mandatoryFlags = consensus.Verify_flags_p2sh
    62  
    63  var standardFlags = mandatoryFlags |
    64  	consensus.Verify_flags_dersig |
    65  	consensus.Verify_flags_strictenc |
    66  	consensus.Verify_flags_minimaldata |
    67  	consensus.Verify_flags_nulldummy |
    68  	consensus.Verify_flags_discourage_upgradable_nops |
    69  	consensus.Verify_flags_cleanstack |
    70  	consensus.Verify_flags_checklocktimeverify |
    71  	consensus.Verify_flags_low_s
    72  
    73  // ExecResult is the result of processing a transaction
    74  type ExecResult struct {
    75  	SumCurrentOutputs uint64
    76  	SumPriorOutputs   uint64
    77  	IsCoinbase        bool
    78  }
    79  
    80  // Execute processes the given transaction and outputs a result
    81  func (u *UTXO) Execute(txData []byte) (*ExecResult, error) {
    82  	newTX := ParseUTXOBytes(txData)
    83  	txHash := u.GetTransactionHash(txData)
    84  	execResult := &ExecResult{}
    85  	// Loop through outputs first
    86  	for index, output := range newTX.Txout {
    87  		currKey := &Key{TxHashAsHex: hex.EncodeToString(txHash[:]), TxIndex: uint32(index)}
    88  		_, ok, err := u.Store.GetState(*currKey)
    89  		if err != nil {
    90  			return nil, fmt.Errorf("Error getting state from store:  %s", err)
    91  		}
    92  		if ok == true {
    93  			// COLLISION
    94  			return nil, fmt.Errorf("COLLISION detected for key = %v, with output script length = %d", currKey, len(output.Script))
    95  		}
    96  		// Store the output in utxo
    97  		u.Store.PutState(*currKey, &TX_TXOUT{Script: output.Script, Value: output.Value})
    98  		execResult.SumCurrentOutputs += output.Value
    99  	}
   100  	// Now loop over inputs,
   101  	for index, input := range newTX.Txin {
   102  		prevTxHash := input.SourceHash
   103  		prevOutputIx := input.Ix
   104  		if u.IsCoinbase(prevOutputIx) {
   105  			execResult.IsCoinbase = true
   106  			//fmt.Println("COINBASE!!")
   107  		} else {
   108  			//fmt.Println("NOT COINBASE!!")
   109  			// NOT coinbase, need to verify
   110  			keyToPrevOutput := &Key{TxHashAsHex: hex.EncodeToString(prevTxHash), TxIndex: prevOutputIx}
   111  			value, ok, err := u.Store.GetState(*keyToPrevOutput)
   112  			if err != nil {
   113  				return nil, fmt.Errorf("Error getting state from store:  %s", err)
   114  			}
   115  			if !ok {
   116  				// Previous output not fouund,
   117  				return nil, fmt.Errorf("Could not find previous transaction output with key = %v", keyToPrevOutput)
   118  			}
   119  			// Call Verify_script
   120  			txInputIndex := uint(index)
   121  			result := consensus.Verify_script(&txData[0], int64(len(txData)), &value.Script[0], int64(len(value.Script)), txInputIndex, uint(standardFlags))
   122  			if result != consensus.Verify_result_eval_true {
   123  				result = consensus.Verify_script(&txData[0], int64(len(txData)), &value.Script[0], int64(len(value.Script)), txInputIndex, uint(mandatoryFlags))
   124  				if result != consensus.Verify_result_eval_true {
   125  					return nil, fmt.Errorf("Unexpected result from verify_script, expected %d, got %d, perhaps it is %d", consensus.Verify_result_eval_true, result, consensus.Verify_result_invalid_stack_operation)
   126  				}
   127  			}
   128  			// Verified, now remove prior outputs
   129  			u.Store.DelState(*keyToPrevOutput)
   130  			execResult.SumPriorOutputs += value.Value
   131  		}
   132  
   133  		hex := hex.EncodeToString(txHash[:])
   134  		fmt.Printf("PUT TRAN %s", hex)
   135  		u.Store.PutTran(hex, txData)
   136  	}
   137  	return execResult, nil
   138  }
   139  
   140  // Query search the storage for a given transaction hash
   141  func (u *UTXO) Query(txHashHex string) pb.Response {
   142  	tx, _, err := u.Store.GetTran(txHashHex)
   143  	return tx, err
   144  }