fix: epoch decoding

src/codec.spec.ts

@@ -17,6 +17,7 @@ import {
 } from "js-waku/lib/waku_message/version_1";
 
 import { RLNDecoder, RLNEncoder } from "./codec.js";
+import { epochBytesToInt } from "./epoch.js";
 import { RlnMessage } from "./message.js";
 
 import * as rln from "./index.js";
@@ -47,7 +48,6 @@ describe("RLN codec with version 0", () => {
 
     expect(bytes).to.not.be.undefined;
     const protoResult = await rlnDecoder.fromWireToProtoObj(bytes!);
-
     expect(protoResult).to.not.be.undefined;
     const msg = (await rlnDecoder.fromProtoObj(protoResult!))!;
 
@@ -267,3 +267,48 @@ describe("RLN codec with version 1", () => {
     expect(msg.timestamp).to.not.be.undefined;
   });
 });
+
+describe("RLN Codec - epoch", () => {
+  it("toProtoObj", async function () {
+    const rlnInstance = await rln.create();
+    const memKeys = rlnInstance.generateMembershipKey();
+    const index = 0;
+    const payload = new Uint8Array([1, 2, 3, 4, 5]);
+
+    rlnInstance.insertMember(memKeys.IDCommitment);
+
+    const rlnEncoder = new RLNEncoder(
+      new EncoderV0(TestContentTopic),
+      rlnInstance,
+      index,
+      memKeys
+    );
+    const rlnDecoder = new RLNDecoder(
+      rlnInstance,
+      new DecoderV0(TestContentTopic)
+    );
+
+    const proto = await rlnEncoder.toProtoObj({ payload });
+
+    expect(proto).to.not.be.undefined;
+    const msg = (await rlnDecoder.fromProtoObj(
+      proto!
+    )) as RlnMessage<MessageV0>;
+
+    const epochBytes = proto!.rateLimitProof!.epoch;
+    const epoch = epochBytesToInt(epochBytes);
+
+    expect(msg).to.not.be.undefined;
+    expect(msg.rateLimitProof).to.not.be.undefined;
+
+    expect(msg.verify()).to.be.true;
+    expect(msg.epoch).to.not.be.undefined;
+    expect(msg.epoch!.toString(10).length).to.eq(9);
+    expect(msg.epoch).to.eq(epoch);
+
+    expect(msg.contentTopic).to.eq(TestContentTopic);
+    expect(msg.msg.version).to.eq(0);
+    expect(msg.payload).to.deep.eq(payload);
+    expect(msg.timestamp).to.not.be.undefined;
+  });
+});

src/epoch.ts

@@ -23,7 +23,7 @@ export function epochIntToBytes(epoch: number): Uint8Array {
 }
 
 export function epochBytesToInt(bytes: Uint8Array): number {
-  const dv = new DataView(bytes.buffer);
+  const dv = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
   const epoch = dv.getUint32(0, true);
   log("decoded epoch", epoch, bytes);
   return epoch;