Use the new Soroban RPC simulation method when preparing transactions

.github/workflows/tests.yml

@@ -25,7 +25,9 @@ jobs:
           node-version: ${{ matrix.node-version }}
 
       - name: Install Dependencies
-        run: yarn install
+        run: |
+          yarn cache clean
+          yarn install --network-concurrency 1
 
       - name: Build
         run: gulp

CHANGELOG.md

@@ -4,6 +4,10 @@
 
 A breaking change should be clearly marked in this log.
 
+#### Pending
+updated prepare transaction for new soroban simulation results and fees [#76](https://github.com/stellar/js-soroban-client/issues/76)
+
+
 #### 0.5.1
 
 * remove params from jsonrpc post payload if empty. [#70](https://github.com/stellar/js-soroban-client/pull/70)

package.json

@@ -138,7 +138,7 @@
     "axios": "0.25.0",
     "es6-promise": "^4.2.4",
     "lodash": "4.17.21",
-    "stellar-base": "8.2.2-soroban.12",
+    "stellar-base": "https://github.com/stellar/js-stellar-base\\#host_functions_ts",
     "urijs": "^1.19.1"
   }
 }

src/server.ts

@@ -372,8 +372,11 @@ export class Server {
   }
 
   /**
-   * Submit a trial contract invocation, then add the expected ledger footprint
-   * and auth into the transaction so it is ready for signing & sending.
+   * Submit a trial contract invocation, first run a simulation of the contract
+   * invocation, and use the results to set the ledger footprint
+   * and auth into the returned transaction so it is ready for signing & sending.
+   * The return transaction will also have an updated fee if the contract resource
+   * fees estimated from simulation exceed the fee from input transaction.
    *
    * @example
    * const contractId = '0000000000000000000000000000000000000000000000000000000000000001';
@@ -419,25 +422,29 @@ export class Server {
    *    passphrase. If not passed, the current network passphrase will be requested
    *    from the server via `getNetwork`.
    * @returns {Promise<Transaction | FeeBumpTransaction>} Returns a copy of the
-   *    transaction, with the expected ledger footprint added.
+   *    transaction, with the expected ledger footprint and authorizations added
+   *    and the transaction fee will automatically be adjusted if it was lower
+   *    than the soroban contract minimum resource fees discovered from the simulation,
+   *    it will be set to that minimum resource fees value instead.
+   *
    */
   public async prepareTransaction(
     transaction: Transaction | FeeBumpTransaction,
     networkPassphrase?: string,
   ): Promise<Transaction | FeeBumpTransaction> {
-    const [{ passphrase }, { error, results }] = await Promise.all([
+    const [{ passphrase }, simResponse] = await Promise.all([
       networkPassphrase
         ? Promise.resolve({ passphrase: networkPassphrase })
         : this.getNetwork(),
       this.simulateTransaction(transaction),
     ]);
-    if (error) {
-      throw error;
+    if (simResponse.error) {
+      throw simResponse.error;
     }
-    if (!results) {
+    if (!simResponse.results || simResponse.results.length < 1) {
       throw new Error("transaction simulation failed");
     }
-    return assembleTransaction(transaction, passphrase, results);
+    return assembleTransaction(transaction, passphrase, simResponse);
   }
 
   /**

src/soroban_rpc.ts

@@ -112,16 +112,22 @@ export namespace SorobanRpc {
     latestLedgerCloseTime: number;
   }
 
+  export interface SimulateHostFunctionResult {
+    // each string is ContractAuth XDR in base64
+    auth: string[];
+    // function response as SCVal XDR in base64
+    xdr: string;
+  }
+
   export interface SimulateTransactionResponse {
     id: string;
-    cost: Cost;
-    results?: Array<{
-      xdr: string;
-      footprint: string;
-      auth: string[];
-      events: string[];
-    }>;
     error?: jsonrpc.Error;
+    // this is SorobanTransactionData XDR in base64
+    transactionData: string;
+    events: string[];
+    minResourceFee: string;
+    results: SimulateHostFunctionResult[];
     latestLedger: number;
+    cost: Cost;
   }
 }

src/transaction.ts

@@ -6,35 +6,53 @@ import {
   TransactionBuilder,
   xdr,
 } from "stellar-base";
+import { SorobanRpc } from "./soroban_rpc";
 
 // TODO: Transaction is immutable, so we need to re-build it here. :(
 export function assembleTransaction(
   raw: Transaction | FeeBumpTransaction,
   networkPassphrase: string,
-  simulated: Array<null | {
-    footprint: Buffer | string | xdr.LedgerFootprint;
-    auth: Array<Buffer | string | xdr.ContractAuth>;
-  }>,
+  simulation: SorobanRpc.SimulateTransactionResponse,
 ): Transaction {
   if ("innerTransaction" in raw) {
     // TODO: Handle feebump transactions
     return assembleTransaction(
       raw.innerTransaction,
       networkPassphrase,
-      simulated,
+      simulation,
     );
   }
 
-  if (simulated.length !== raw.operations.length) {
+  if (
+    raw.operations.length !== 1 ||
+    raw.operations[0].type !== "invokeHostFunction"
+  ) {
     throw new Error(
-      "number of simulated operations not equal to number of transaction operations",
+      "unsupported operation type, must be only one InvokeHostFunctionOp in the transaction.",
+    );
+  }
+
+  const rawInvokeHostFunctionOp: any = raw.operations[0];
+
+  if (
+    !rawInvokeHostFunctionOp.functions ||
+    !simulation.results ||
+    rawInvokeHostFunctionOp.functions.length !== simulation.results.length
+  ) {
+    throw new Error(
+      "preflight simulation results do not contain same count of HostFunctions that InvokeHostFunctionOp in the transaction has.",
     );
   }
 
-  // TODO: Figure out a cleaner way to clone this transaction.
   const source = new Account(raw.source, `${parseInt(raw.sequence, 10) - 1}`);
-  const txn = new TransactionBuilder(source, {
-    fee: raw.fee,
+  const classicFeeNum = parseInt(raw.fee, 10) || 0;
+  const minResourceFeeNum = parseInt(simulation.minResourceFee, 10) || 0;
+  const txnBuilder = new TransactionBuilder(source, {
+    // automatically update the 'classic' tx fee if min resource fees from simulation response
+    // surpass that value.
+    // 'classic' fees are measured as the product of tx.fee * 'number of operations', In soroban contract tx,
+    // there can only be single operation in the tx, so can safely make simplification of classic fee = tx.fee.
+    fee: Math.max(classicFeeNum + minResourceFeeNum, classicFeeNum).toString(),
     memo: raw.memo,
     networkPassphrase,
     timebounds: raw.timeBounds,
@@ -44,35 +62,47 @@ export function assembleTransaction(
     minAccountSequenceLedgerGap: raw.minAccountSequenceLedgerGap,
     extraSigners: raw.extraSigners,
   });
-  for (let i = 0; i < raw.operations.length; i++) {
-    const rawOp = raw.operations[i];
-    if ("function" in rawOp) {
-      const sim = simulated[i];
-      if (!sim) {
-        throw new Error("missing simulated operation");
-      }
-      let footprint = sim.footprint ?? rawOp.footprint;
-      if (!(footprint instanceof xdr.LedgerFootprint)) {
-        footprint = xdr.LedgerFootprint.fromXDR(footprint.toString(), "base64");
-      }
-      const auth = (sim.auth ?? rawOp.auth).map((a) =>
-        a instanceof xdr.ContractAuth
-          ? a
-          : xdr.ContractAuth.fromXDR(a.toString(), "base64"),
-      );
-      // TODO: Figure out a cleaner way to clone these operations
-      txn.addOperation(
-        Operation.invokeHostFunction({
-          function: rawOp.function,
-          parameters: rawOp.parameters,
-          footprint,
-          auth,
-        }),
-      );
-    } else {
-      // TODO: Handle this.
-      throw new Error("Unsupported operation type");
-    }
+
+  // apply the pre-built Auth from simulation onto each Tx/Op/HostFunction
+  // invocation
+  const authDecoratedHostFunctions = simulation.results.map(
+    (functionSimulationResult, i) => {
+      const hostFn: xdr.HostFunction = rawInvokeHostFunctionOp.functions[i];
+      hostFn.auth(buildContractAuth(functionSimulationResult.auth));
+      return hostFn;
+    },
+  );
+
+  txnBuilder.addOperation(
+    Operation.invokeHostFunctions({
+      functions: authDecoratedHostFunctions,
+    }),
+  );
+
+  // apply the pre-built Soroban Tx Ext from simulation onto the Tx
+  txnBuilder.setExt(buildExt(simulation.transactionData));
+
+  return txnBuilder.build();
+}
+
+function buildExt(sorobanTxDataStr: string) {
+  const sorobanTxData: xdr.SorobanTransactionData = xdr.SorobanTransactionData.fromXDR(
+    sorobanTxDataStr,
+    "base64",
+  );
+
+  // TODO - remove this workaround to use constructor on js-xdr union
+  //       and use the typescript generated static factory method once fixed
+  //       https://github.com/stellar/dts-xdr/issues/5
+  // @ts-ignore
+  const txExt = new xdr.TransactionExt(1, sorobanTxData);
+  return txExt;
+}
+
+function buildContractAuth(auths: string[]): xdr.ContractAuth[] {
+  const contractAuths: xdr.ContractAuth[] = [];
+  for (const authStr of auths) {
+    contractAuths.push(xdr.ContractAuth.fromXDR(authStr, "base64"));
   }
-  return txn.build();
+  return contractAuths;
 }

test/unit/server/simulate_transaction_test.js

@@ -5,24 +5,75 @@ describe("Server#simulateTransaction", function() {
     "56199647068161",
   );
 
+  const simulationResponse = {
+    transactionData: new SorobanClient.xdr.SorobanTransactionData({
+      resources: new SorobanClient.xdr.SorobanResources({
+        footprint: new SorobanClient.xdr.LedgerFootprint({
+          readOnly: [],
+          readWrite: [],
+        }),
+        instructions: 0,
+        readBytes: 0,
+        writeBytes: 0,
+        extendedMetaDataSizeBytes: 0,
+      }),
+      refundableFee: SorobanClient.xdr.Int64.fromString("0"),
+      ext: new SorobanClient.xdr.ExtensionPoint(0),
+    }).toXDR("base64"),
+    events: [],
+    minResourceFee: "15",
+    results: [
+      {
+        auth: [
+          new SorobanClient.xdr.ContractAuth({
+            addressWithNonce: null,
+            rootInvocation: new SorobanClient.xdr.AuthorizedInvocation({
+              contractId: Buffer.alloc(32),
+              functionName: "fn",
+              args: [],
+              subInvocations: [],
+            }),
+            signatureArgs: [],
+          }).toXDR("base64"),
+        ],
+        xdr: SorobanClient.xdr.ScVal.scvU32(0)
+          .toXDR()
+          .toString("base64"),
+      },
+    ],
+    latestLedger: 3,
+    cost: {
+      cpuInsns: "0",
+      memBytes: "0",
+    },
+  };
+
   beforeEach(function() {
     this.server = new SorobanClient.Server(serverUrl);
     this.axiosMock = sinon.mock(AxiosClient);
-    let transaction = new SorobanClient.TransactionBuilder(account, {
-      fee: 100,
-      networkPassphrase: SorobanClient.Networks.TESTNET,
-      v1: true,
-    })
-      .addOperation(
-        SorobanClient.Operation.payment({
-          destination:
-            "GASOCNHNNLYFNMDJYQ3XFMI7BYHIOCFW3GJEOWRPEGK2TDPGTG2E5EDW",
-          asset: SorobanClient.Asset.native(),
-          amount: "100.50",
-        }),
-      )
-      .setTimeout(SorobanClient.TimeoutInfinite)
-      .build();
+    const source = new SorobanClient.Account(
+      "GBZXN7PIRZGNMHGA7MUUUF4GWPY5AYPV6LY4UV2GL6VJGIQRXFDNMADI",
+      "1",
+    );
+    function emptyContractTransaction() {
+      return new SorobanClient.TransactionBuilder(source, {
+        fee: 100,
+        networkPassphrase: "Test",
+        v1: true,
+      })
+        .addOperation(
+          SorobanClient.Operation.invokeHostFunction({
+            args: new SorobanClient.xdr.HostFunctionArgs.hostFunctionTypeInvokeContract(
+              [],
+            ),
+            auth: [],
+          }),
+        )
+        .setTimeout(SorobanClient.TimeoutInfinite)
+        .build();
+    }
+
+    const transaction = emptyContractTransaction();
     transaction.sign(keypair);
 
     this.transaction = transaction;
@@ -38,26 +89,6 @@ describe("Server#simulateTransaction", function() {
     this.axiosMock.restore();
   });
 
-  const result = {
-    cost: {
-      cpuInsns: "10000",
-      memBytes: "10000",
-    },
-    results: [
-      {
-        xdr: SorobanClient.xdr.ScVal.scvU32(0)
-          .toXDR()
-          .toString("base64"),
-        footprint: new SorobanClient.xdr.LedgerFootprint({
-          readOnly: [],
-          readWrite: [],
-        }).toXDR("base64"),
-        events: [],
-      },
-    ],
-    latestLedger: 1,
-  };
-
   it("simulates a transaction", function(done) {
     this.axiosMock
       .expects("post")
@@ -67,12 +98,14 @@ describe("Server#simulateTransaction", function() {
         method: "simulateTransaction",
         params: [this.blob],
       })
-      .returns(Promise.resolve({ data: { id: 1, result } }));
+      .returns(
+        Promise.resolve({ data: { id: 1, result: simulationResponse } }),
+      );
 
     this.server
       .simulateTransaction(this.transaction)
       .then(function(response) {
-        expect(response).to.be.deep.equal(result);
+        expect(response).to.be.deep.equal(simulationResponse);
         done();
       })
       .catch(function(err) {