CDSI Support

ts/textsecure/cds/CDSBase.ts

@@ -0,0 +1,67 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import ProxyAgent from 'proxy-agent';
+
+import type {
+  CDSAuthType,
+  CDSRequestOptionsType,
+  CDSResponseType,
+} from './Types.d';
+import type { LoggerType } from '../../types/Logging';
+import { isOlderThan } from '../../util/timestamp';
+import { HOUR } from '../../util/durations';
+
+// It is 24 hours, but we don't want latency between server and client to be
+// count.
+const CACHED_AUTH_TTL = 23 * HOUR;
+
+export type CDSBaseOptionsType = Readonly<{
+  logger: LoggerType;
+  proxyUrl?: string;
+  getAuth(): Promise<CDSAuthType>;
+}>;
+
+export type CachedAuthType = Readonly<{
+  timestamp: number;
+  auth: CDSAuthType;
+}>;
+
+export abstract class CDSBase<
+  Options extends CDSBaseOptionsType = CDSBaseOptionsType
+> {
+  protected readonly logger: LoggerType;
+  protected readonly proxyAgent?: ReturnType<typeof ProxyAgent>;
+  protected cachedAuth?: CachedAuthType;
+
+  constructor(protected readonly options: Options) {
+    this.logger = options.logger;
+
+    if (options.proxyUrl) {
+      this.proxyAgent = new ProxyAgent(options.proxyUrl);
+    }
+  }
+
+  public abstract request(
+    options: CDSRequestOptionsType
+  ): Promise<CDSResponseType>;
+
+  protected async getAuth(): Promise<CDSAuthType> {
+    if (this.cachedAuth) {
+      if (isOlderThan(this.cachedAuth.timestamp, CACHED_AUTH_TTL)) {
+        this.cachedAuth = undefined;
+      } else {
+        return this.cachedAuth.auth;
+      }
+    }
+
+    const auth = await this.options.getAuth();
+
+    this.cachedAuth = {
+      auth,
+      timestamp: Date.now(),
+    };
+
+    return auth;
+  }
+}