[FEAT] Direct API get for last message by subject will now set the su…

…bject as part of the request subject, rather than include it on the payload of the request. This allows for downstream clients, such as KV, to clamp on permissions for a GET.j

nats-base-client/jsmdirect_api.ts

@@ -18,7 +18,9 @@ import {
   DirectMsgHeaders,
   DirectMsgRequest,
   DirectStreamAPI,
+  Empty,
   JetStreamOptions,
+  LastForMsgRequest,
   Msg,
   NatsConnection,
   StoredMsg,
@@ -37,9 +39,21 @@ export class DirectStreamAPIImpl extends BaseApiClient
     query: DirectMsgRequest,
   ): Promise<StoredMsg> {
     validateStreamName(stream);
+    // if doing a last_by_subj request, we append the subject
+    // this allows last_by_subj to be subject to permissions (KV)
+    let qq: DirectMsgRequest | null = query;
+    const { last_by_subj } = qq as LastForMsgRequest;
+    if (last_by_subj) {
+      qq = null;
+    }
+
+    const payload = qq ? this.jc.encode(qq) : Empty;
+    const subj = last_by_subj
+      ? `$JS.API.DIRECT.GET.${stream}.${last_by_subj}`
+      : `$JS.API.DIRECT.GET.${stream}`;
     const r = await this.nc.request(
-      `$JS.API.DIRECT.GET.${stream}`,
-      this.jc.encode(query),
+      subj,
+      payload,
     );
 
     // response is not a JS.API response

tests/jsm_test.ts

@@ -31,7 +31,6 @@ import {
   JSONCodec,
   jwtAuthenticator,
   nanos,
-  NatsConnectionImpl,
   NatsError,
   nkeys,
   nuid,
@@ -1210,9 +1209,6 @@ Deno.test("jsm - direct getMessage", async () => {
   await js.publish("bar", sc.encode("d"), { expect: { lastSequence: 3 } });
   await js.publish("foo", sc.encode("e"), { expect: { lastSequence: 4 } });
 
-  const nci = nc as NatsConnectionImpl;
-  nci.options.debug = true;
-
   let m = await jsm.direct.getMessage("A", { seq: 0, next_by_subj: "bar" });
   assertEquals(m.seq, 4);