Atomic Transaction Support for Backend (#560)

routes/atomic_txns.go

@@ -0,0 +1,106 @@
+package routes
+
+import (
+	"encoding/hex"
+	"encoding/json"
+	"fmt"
+	"github.com/deso-protocol/core/lib"
+	"io"
+	"net/http"
+)
+
+type CreateAtomicTxnsWrapperRequest struct {
+	Transactions []*lib.MsgDeSoTxn
+	ExtraData    map[string]string
+}
+
+type CreateAtomicTxnsWrapperResponse struct {
+	// TransactionsWrapped as a helpful sanity check for the caller of the
+	// CreateAtomicTxnsWrapper endpoint. That being said, the caller should
+	// also sanity check that the returned wrapper transaction has the atomic
+	// transactions ordered correctly.
+	TransactionsWrapped uint64 `safeForLogging:"true"`
+
+	// TotalFeeNanos represents the total fees paid cumulatively by all
+	// wrapper atomic transactions and is consistent with the
+	// returned Transaction.TxnFeeNanos field.
+	TotalFeeNanos  uint64
+	Transaction    *lib.MsgDeSoTxn
+	TransactionHex string
+}
+
+func (fes *APIServer) CreateAtomicTxnsWrapper(ww http.ResponseWriter, req *http.Request) {
+	decoder := json.NewDecoder(io.LimitReader(req.Body, MaxRequestBodySizeBytes))
+	requestData := CreateAtomicTxnsWrapperRequest{}
+	if err := decoder.Decode(&requestData); err != nil {
+		_AddBadRequestError(ww, fmt.Sprintf("CreateAtomicTxnsWrapper: Error parsing request body: %v", err))
+		return
+	}
+
+	// Grab a view (needed for getting global params, etc).
+	utxoView, err := fes.backendServer.GetMempool().GetAugmentedUniversalView()
+	if err != nil {
+		_AddBadRequestError(ww, fmt.Sprintf("CreateAtomicTxnsWrapper: Error getting utxoView: %v", err))
+		return
+	}
+
+	// Validate the request data.
+	if len(requestData.Transactions) == 0 {
+		_AddBadRequestError(ww, fmt.Sprint("CreateAtomicTxnsWrapper: must have at least one transaction "+
+			"in Transactions"))
+		return
+	}
+
+	// Encode the ExtraData map.
+	extraData, err := EncodeExtraDataMap(requestData.ExtraData)
+	if err != nil {
+		_AddBadRequestError(ww, fmt.Sprintf("CreateAtomicTxnsWrapper: Problem encoding ExtraData: %v", err))
+		return
+	}
+
+	// Construct the atomic transactions wrapper transaction type.
+	txn, totalFees, err := fes.blockchain.CreateAtomicTxnsWrapper(requestData.Transactions, extraData)
+	if err != nil {
+		_AddBadRequestError(ww, fmt.Sprintf("CreateAtomicTxnsWrapper: Problem constructing transaction: %v", err))
+		return
+	}
+
+	// Serialize the transaction.
+	txnBytes, err := txn.ToBytes(true)
+	if err != nil {
+		_AddBadRequestError(ww, fmt.Sprintf("CreateAtomicTxnsWrapper: Problem serializing transaction: %v", err))
+		return
+	}
+	txnSizeBytes := uint64(len(txnBytes))
+
+	// Validate that:
+	// 	(1) The resulting transaction is not over the size limit of an atomic transaction.
+	// 	(2) The resulting wrapper transactions have sufficient fees to cover the wrapper.
+	if txnSizeBytes > utxoView.GetCurrentGlobalParamsEntry().MaxTxnSizeBytesPoS {
+		_AddBadRequestError(ww, fmt.Sprint("CreateAtomicTxnsWrapper: Resulting wrapper transaction too large"))
+		return
+	}
+	if txnSizeBytes != 0 && utxoView.GlobalParamsEntry.MinimumNetworkFeeNanosPerKB != 0 {
+		// Check for overflow or minimum network fee not met.
+		if totalFees != ((totalFees*1000)/1000) ||
+			(totalFees*1000)/uint64(txnSizeBytes) < utxoView.GlobalParamsEntry.MinimumNetworkFeeNanosPerKB {
+			_AddBadRequestError(ww, fmt.Sprint("CreateAtomicTxnsWrapper: Transactions used to construct"+
+				" atomic transaction do not cumulatively pay sufficient network fees to cover wrapper"))
+			return
+		}
+	}
+
+	// Construct a response.
+	res := CreateAtomicTxnsWrapperResponse{
+		TransactionsWrapped: uint64(len(txn.TxnMeta.(*lib.AtomicTxnsWrapperMetadata).Txns)),
+		TotalFeeNanos:       totalFees,
+		Transaction:         txn,
+		TransactionHex:      hex.EncodeToString(txnBytes),
+	}
+
+	if err = json.NewEncoder(ww).Encode(res); err != nil {
+		_AddInternalServerError(ww,
+			fmt.Sprintf("CreateAtomicTxnsWrapper: Problem serializing object to JSON: %v", err))
+		return
+	}
+}

routes/server.go

@@ -331,6 +331,9 @@ const (
 	RoutePathCoinUnlock             = "/api/v0/coin-unlock"
 	RoutePathLockupYieldCurvePoints = "/api/v0/lockup-yield-curve-points"
 	RoutePathLockedBalanceEntries   = "/api/v0/locked-balance-entries"
+
+	// atomic_txns.go
+	RoutePathCreateAtomicTxnsWrapper = "/api/v0/create-atomic-txns-wrapper"
 )
 
 // APIServer provides the interface between the blockchain and things like the
@@ -1419,6 +1422,13 @@ func (fes *APIServer) NewRouter() *muxtrace.Router {
 			fes.LockedBalanceEntries,
 			PublicAccess,
 		},
+		{
+			"CreateAtomicTxnsWrapper",
+			[]string{"POST", "OPTIONS"},
+			RoutePathCreateAtomicTxnsWrapper,
+			fes.CreateAtomicTxnsWrapper,
+			PublicAccess,
+		},
 		// Jumio Routes
 		{
 			"JumioBegin",