[FIX] cross language compatible meta subject (#372)

BREAKING CHANGE

nats-base-client/base64.ts

@@ -0,0 +1,41 @@
+export class Base64Codec {
+  static encode(bytes: string | Uint8Array): string {
+    if (typeof bytes === "string") {
+      return btoa(bytes);
+    }
+    const a = Array.from(bytes);
+    return btoa(String.fromCharCode(...a));
+  }
+
+  static decode(s: string, binary = false): Uint8Array | string {
+    const bin = atob(s);
+    if (!binary) {
+      return bin;
+    }
+    return Uint8Array.from(bin, (c) => c.charCodeAt(0));
+  }
+}
+
+export class Base64UrlCodec {
+  static encode(bytes: string | Uint8Array): string {
+    return Base64UrlCodec.toB64URLEncoding(Base64Codec.encode(bytes));
+  }
+
+  static decode(s: string, binary = false): Uint8Array | string {
+    return Base64Codec.decode(Base64UrlCodec.fromB64URLEncoding(s), binary);
+  }
+
+  static toB64URLEncoding(b64str: string): string {
+    return b64str
+      .replace(/=/g, "")
+      .replace(/\+/g, "-")
+      .replace(/\//g, "_");
+  }
+
+  static fromB64URLEncoding(b64str: string): string {
+    // pads are % 4, but not necessary on decoding
+    return b64str
+      .replace(/_/g, "/")
+      .replace(/-/g, "+");
+  }
+}

nats-base-client/objectstore.ts

@@ -35,6 +35,7 @@ import {
   StreamInfoRequestOptions,
 } from "./types.ts";
 import { validateBucket, validateKey } from "./kv.ts";
+import { Base64UrlCodec } from "./base64.ts";
 import { JSONCodec } from "./codec.ts";
 import { nuid } from "./nuid.ts";
 import { deferred } from "./util.ts";
@@ -248,7 +249,7 @@ export class ObjectStoreImpl implements ObjectStore {
       return Promise.reject(error);
     }
 
-    const meta = `$O.${this.name}.M.${obj}`;
+    const meta = this._metaSubject(obj);
     try {
       const m = await this.jsm.streams.getMessage(this.stream, {
         last_by_subj: meta,
@@ -674,7 +675,7 @@ export class ObjectStoreImpl implements ObjectStore {
   }
 
   _metaSubject(n: string): string {
-    return `$O.${this.name}.M.${n}`;
+    return `$O.${this.name}.M.${Base64UrlCodec.encode(n)}`;
   }
 
   _metaSubjectAll(): string {

tests/objectstore_test.ts

@@ -33,6 +33,7 @@ import { assertRejects } from "https://deno.land/std@0.152.0/testing/asserts.ts"
 import { equals } from "https://deno.land/std@0.152.0/bytes/mod.ts";
 import { ObjectInfo, ObjectStoreMeta } from "../nats-base-client/types.ts";
 import { SHA256 } from "../nats-base-client/sha256.js";
+import { Base64UrlCodec } from "../nats-base-client/base64.ts";
 
 function readableStreamFrom(data: Uint8Array): ReadableStream<Uint8Array> {
   return new ReadableStream<Uint8Array>({
@@ -676,9 +677,14 @@ Deno.test("objectstore - sanitize", async () => {
   const info = await os.status({
     subjects_filter: ">",
   });
-  assertEquals(info.streamInfo.state?.subjects!["$O.test.M.has_dots_here"], 1);
   assertEquals(
-    info.streamInfo.state.subjects!["$O.test.M.the_spaces_are_here"],
+    info.streamInfo.state
+      ?.subjects![`$O.test.M.${Base64UrlCodec.encode("has_dots_here")}`],
+    1,
+  );
+  assertEquals(
+    info.streamInfo.state
+      .subjects![`$O.test.M.${Base64UrlCodec.encode("the_spaces_are_here")}`],
     1,
   );