neo-go/pkg/rpc/txBuilder.go

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package rpc
import (
"bytes"
"github.com/CityOfZion/neo-go/pkg/core/transaction"
"github.com/CityOfZion/neo-go/pkg/crypto"
"github.com/CityOfZion/neo-go/pkg/crypto/keys"
"github.com/CityOfZion/neo-go/pkg/util"
errs "github.com/pkg/errors"
)
// CreateRawContractTransaction returns contract-type Transaction built from specified parameters.
func CreateRawContractTransaction(params ContractTxParams) (*transaction.Transaction, error) {
var (
err error
tx = transaction.NewContractTX()
toAddressHash, fromAddressHash util.Uint160
fromAddress string
senderOutput, receiverOutput *transaction.Output
inputs []transaction.Input
spent util.Fixed8
witness transaction.Witness
wif, assetID, address, amount, balancer = params.wif, params.assetID, params.address, params.value, params.balancer
)
fromAddress = wif.PrivateKey.Address()
if fromAddressHash, err = crypto.Uint160DecodeAddress(fromAddress); err != nil {
return nil, errs.Wrapf(err, "Failed to take script hash from address: %v", fromAddress)
}
if toAddressHash, err = crypto.Uint160DecodeAddress(address); err != nil {
return nil, errs.Wrapf(err, "Failed to take script hash from address: %v", address)
}
tx.Attributes = append(tx.Attributes,
&transaction.Attribute{
Usage: transaction.Script,
Data: fromAddressHash.Bytes(),
})
if inputs, spent, err = balancer.CalculateInputs(fromAddress, assetID, amount); err != nil {
return nil, errs.Wrap(err, "Failed to get inputs for transaction")
}
for _, input := range inputs {
tx.AddInput(&input)
}
if senderUnspent := spent - amount; senderUnspent > 0 {
senderOutput = transaction.NewOutput(assetID, senderUnspent, fromAddressHash)
tx.AddOutput(senderOutput)
}
receiverOutput = transaction.NewOutput(assetID, amount, toAddressHash)
tx.AddOutput(receiverOutput)
if witness.InvocationScript, err = GetInvocationScript(tx, wif); err != nil {
return nil, errs.Wrap(err, "Failed to create invocation script")
}
witness.VerificationScript = wif.GetVerificationScript()
tx.Scripts = append(tx.Scripts, &witness)
tx.Hash()
return tx, nil
}
// GetInvocationScript returns NEO VM script containing transaction signature.
func GetInvocationScript(tx *transaction.Transaction, wif keys.WIF) ([]byte, error) {
const (
pushbytes64 = 0x40
)
var (
err error
buf = new(bytes.Buffer)
signature []byte
)
if err = tx.EncodeBinary(buf); err != nil {
return nil, errs.Wrap(err, "Failed to encode transaction to binary")
}
data := buf.Bytes()
signature, err = wif.PrivateKey.Sign(data[:(len(data) - 1)])
if err != nil {
return nil, errs.Wrap(err, "Failed ti sign transaction with private key")
}
return append([]byte{pushbytes64}, signature...), nil
}