fix(relayer): Ensure argument keys are sorted before hashing

src/utils/EventUtils.ts

@@ -216,8 +216,26 @@ export class EventManager {
    */
   hashEvent(event: Log): string {
     const { event: eventName, blockNumber, blockHash, transactionHash, transactionIndex, logIndex, args } = event;
-    const _args = Object.values(args).join("-");
+    const _args = this.flattenObject(args);
     const key = `${eventName}-${blockNumber}-${blockHash}-${transactionHash}-${transactionIndex}-${logIndex}-${_args}`;
     return ethersUtils.id(key);
   }
+
+  /**
+   * Recurse through an object and sort its keys in order to produce an ordered string of values.
+   * @param obj Object to iterate through.
+   * @returns string A hyphenated string containing all arguments of the object, sorted by key.
+   */
+  private flattenObject(obj: Record<string, unknown>): string {
+    const args = Object.keys(obj)
+      .sort()
+      .map((k) => {
+        const val = obj[k];
+        // When val is a nested object, recursively flatten and stringify it.
+        return typeof val === "object" ? this.flattenObject(val as Record<string, unknown>) : val;
+      })
+      .join("-");
+
+    return args;
+  }
 }

test/EventManager.ts

@@ -116,7 +116,7 @@ describe("EventManager: Event Handling ", async function () {
     expect(events.length).to.equal(0);
   });
 
-  it("Hashes events correctly", async function () {
+  it("Hashes events correctly: uniqueness", async function () {
     const log1 = eventTemplate;
     const hash1 = eventMgr.hashEvent(log1);
     expect(hash1).to.exist;
@@ -130,6 +130,45 @@ describe("EventManager: Event Handling ", async function () {
     expect(hash3).to.equal(hash1);
   });
 
+  it("Hashes events correctly: sorting", async function () {
+    const log = {
+      ...eventTemplate,
+      args: {
+        c: 3,
+        b: 2,
+        f: {
+          h: 7,
+          i: 8,
+          g: 6,
+        },
+        a: 1,
+        d: 4,
+        e: 5,
+      },
+    };
+    const sortedLog = {
+      ...log,
+      args: {
+        a: 1,
+        b: 2,
+        c: 3,
+        d: 4,
+        e: 5,
+        f: {
+          g: 6,
+          h: 7,
+          i: 8,
+        },
+      },
+    };
+
+    const hash1 = eventMgr.hashEvent(log);
+    expect(hash1).to.exist;
+
+    const hash2 = eventMgr.hashEvent(sortedLog);
+    expect(hash2).to.equal(hash1);
+  });
+
   it("Does not submit duplicate events", async function () {
     expect(quorum).to.equal(2);