Send data-only messages to Android apps that open previews themselves

src/app.test.ts

@@ -35,7 +35,7 @@ async function start(env: Record<string, string> = {}, senders?: Senders) {
   const config = loadConfig({ PORT: "0", ...env });
   const fake: Senders = senders ?? {
     ios: async (token, apnsEnv, alert) => (sent.push({ platform: "ios", token, env: apnsEnv, alert }), next),
-    android: async (token, alert) => (sent.push({ platform: "android", token, alert }), next),
+    android: async (token, alert, opens) => (sent.push({ platform: "android", token, alert, opens }), next),
   };
   const { handle } = createHandler(config, store, fake, quiet);
   server = createServer((req, res) => void handle(req, res));
@@ -51,8 +51,8 @@ function post(path: string, body: unknown, cap?: string) {
   });
 }
 
-async function register(platform = "ios", token = IOS_TOKEN, env?: string): Promise<string> {
-  const res = await post("/v1/devices", { platform, token, env });
+async function register(platform = "ios", token = IOS_TOKEN, env?: string, opens?: boolean): Promise<string> {
+  const res = await post("/v1/devices", { platform, token, env, opens });
   assert.equal(res.status, 201);
   return ((await res.json()) as { capability: string }).capability;
 }
@@ -123,6 +123,30 @@ describe("push relay", () => {
     assert.equal(sent[0].alert.body, "New direct message");
   });
 
+  it("sends a data-only message to an android app that opens previews itself", async () => {
+    const preview = "AQ" + "x".repeat(60);
+    const opener = await register("android", FCM_TOKEN, undefined, true);
+    await post("/v1/push", { kind: "message", preview }, opener);
+    assert.equal(sent[0].opens, true);
+    const message = (fcmMessage("t", sent[0].alert, true) as { message: Record<string, unknown> }).message;
+    assert.ok(!("notification" in message), "Android would show the fixed text itself and never wake the app");
+    assert.deepEqual(message.data, { c: sent[0].alert.tag, p: preview, t: "Gryt", b: "New message" });
+  });
+
+  it("keeps the shown notification for an older android app, and for a push with no preview", async () => {
+    const older = await register("android", FCM_TOKEN);
+    await post("/v1/push", { kind: "message", preview: "AQ" + "x".repeat(60) }, older);
+    assert.equal(sent[0].opens, false);
+    assert.ok("notification" in (fcmMessage("t", sent[0].alert, false) as { message: object }).message);
+    const bare = { title: "Gryt", body: "New message", tag: "0123456789abcdef" };
+    assert.ok("notification" in (fcmMessage("t", bare, true) as { message: object }).message);
+  });
+
+  it("ignores opens on iOS, where the extension does the opening", async () => {
+    const cap = await register("ios", IOS_TOKEN, undefined, true);
+    assert.equal(store.get(hashCapability(cap))?.opens, false);
+  });
+
   it("refuses bad platforms, tokens and kinds", async () => {
     assert.equal((await post("/v1/devices", { platform: "web", token: IOS_TOKEN })).status, 400);
     assert.equal((await post("/v1/devices", { platform: "ios", token: "nothex" })).status, 400);

src/app.ts

@@ -9,7 +9,7 @@ import { alertFor, KINDS, PREVIEW_SHAPE, type Alert, type Kind, type SendResult
 
 export interface Senders {
   ios?: (token: string, env: ApnsEnv, alert: Alert) => Promise<SendResult>;
-  android?: (token: string, alert: Alert) => Promise<SendResult>;
+  android?: (token: string, alert: Alert, opens: boolean) => Promise<SendResult>;
 }
 
 const MAX_BODY = 8 * 1024;
@@ -48,7 +48,8 @@ export function createHandler(config: Config, store: Store, senders: Senders, lo
     if (!registrations.take(ip, clock())) throw new HttpError(429, "too_many_registrations");
 
     const cap = newCapability();
-    store.add(hashCapability(cap), { platform, token: body.token, env }, clock());
+    const opens = platform === "android" && body.opens === true;
+    store.add(hashCapability(cap), { platform, token: body.token, env, opens }, clock());
     store.bump("registered", platform, "", clock());
     sendJson(res, 201, { capability: cap });
   }
@@ -71,7 +72,7 @@ export function createHandler(config: Config, store: Store, senders: Senders, lo
     const alert = alertFor(kind, capabilityTag(cap), preview as string | undefined);
     const result = device.platform === "ios"
       ? await senders.ios?.(device.token, device.env, alert)
-      : await senders.android?.(device.token, alert);
+      : await senders.android?.(device.token, alert, device.opens === true);
     if (!result) throw new HttpError(503, `${device.platform}_unavailable`);
 
     if (result.ok) {

src/db.ts

@@ -20,6 +20,8 @@ export interface Device {
   platform: Platform;
   token: string;
   env: ApnsEnv;
+  /** An Android app that opens sealed previews itself, so it's sent data-only messages (GRYT-1698). */
+  opens?: boolean;
 }
 
 /**
@@ -43,6 +45,9 @@ export class Store {
         last_used_at INTEGER NOT NULL
       )
     `);
+    // Added after the table shipped, so an existing push.db gets the column here.
+    const columns = this.db.prepare("PRAGMA table_info(devices)").all() as { name: string }[];
+    if (!columns.some((c) => c.name === "opens")) this.db.exec("ALTER TABLE devices ADD COLUMN opens INTEGER NOT NULL DEFAULT 0");
     // Kept apart from devices, so the totals outlive every device that made them.
     this.db.exec(`
       CREATE TABLE IF NOT EXISTS daily_counts (
@@ -63,15 +68,15 @@ export class Store {
 
   add(capHash: string, device: Device, now: number): void {
     this.db
-      .prepare("INSERT INTO devices (cap_hash, platform, token, env, created_at, last_used_at) VALUES (?, ?, ?, ?, ?, ?)")
-      .run(capHash, device.platform, device.token, device.env, now, now);
+      .prepare("INSERT INTO devices (cap_hash, platform, token, env, opens, created_at, last_used_at) VALUES (?, ?, ?, ?, ?, ?, ?)")
+      .run(capHash, device.platform, device.token, device.env, device.opens ? 1 : 0, now, now);
   }
 
   get(capHash: string): Device | null {
-    const row = this.db.prepare("SELECT platform, token, env FROM devices WHERE cap_hash = ?").get(capHash) as
-      | { platform: Platform; token: string; env: ApnsEnv }
+    const row = this.db.prepare("SELECT platform, token, env, opens FROM devices WHERE cap_hash = ?").get(capHash) as
+      | { platform: Platform; token: string; env: ApnsEnv; opens: number }
       | undefined;
-    return row ? { platform: row.platform, token: row.token, env: row.env } : null;
+    return row ? { platform: row.platform, token: row.token, env: row.env, opens: row.opens === 1 } : null;
   }
 
   touch(capHash: string, now: number): void {

src/fcm.ts

@@ -15,7 +15,17 @@ export function fcmAssertion(config: FcmConfig, key: KeyObject, nowSec: number):
   return `${body}.${sign("sha256", Buffer.from(body), key).toString("base64url")}`;
 }
 
-export function fcmMessage(deviceToken: string, alert: Alert): object {
+export function fcmMessage(deviceToken: string, alert: Alert, opens = false): object {
+  // Data-only, so Android hands it to the app to open instead of showing the fixed text itself.
+  if (opens && alert.preview) {
+    return {
+      message: {
+        token: deviceToken,
+        android: { priority: "high" },
+        data: { c: alert.tag, p: alert.preview, t: alert.title, b: alert.body },
+      },
+    };
+  }
   return {
     message: {
       token: deviceToken,
@@ -71,12 +81,12 @@ export class FcmSender {
     return this.access.value;
   }
 
-  async send(deviceToken: string, alert: Alert, now = Date.now()): Promise<SendResult> {
+  async send(deviceToken: string, alert: Alert, opens = false, now = Date.now()): Promise<SendResult> {
     try {
       const res = await this.fetchImpl(`${this.sendOrigin}/v1/projects/${this.config.projectId}/messages:send`, {
         method: "POST",
         headers: { authorization: `Bearer ${await this.accessToken(now)}`, "content-type": "application/json" },
-        body: JSON.stringify(fcmMessage(deviceToken, alert)),
+        body: JSON.stringify(fcmMessage(deviceToken, alert, opens)),
         signal: AbortSignal.timeout(TIMEOUT_MS),
       });
       if (res.ok) return { ok: true };

src/index.ts

@@ -21,7 +21,7 @@ const apns = config.apns ? new ApnsSender(config.apns) : null;
 if (apns) senders.ios = (token, env, alert) => apns.send(token, env, alert);
 if (config.fcm) {
   const fcm = new FcmSender(config.fcm);
-  senders.android = (token, alert) => fcm.send(token, alert);
+  senders.android = (token, alert, opens) => fcm.send(token, alert, opens);
 }
 
 const { handle, prune } = createHandler(config, store, senders, log);

src/senders.test.ts

@@ -91,8 +91,8 @@ describe("FCM", () => {
     }) as unknown as typeof fetch;
 
     const fcm = new FcmSender(config, fakeFetch, "https://google.test/token", "https://fcm.test");
-    assert.deepEqual(await fcm.send("tok", alert, 1_000_000), { ok: true });
-    assert.deepEqual(await fcm.send("tok", alert, 1_000_500), { ok: true });
+    assert.deepEqual(await fcm.send("tok", alert, false, 1_000_000), { ok: true });
+    assert.deepEqual(await fcm.send("tok", alert, false, 1_000_500), { ok: true });
     assert.equal(calls.filter((c) => c.url.endsWith("/token")).length, 1);
 
     const assertion = new URLSearchParams(String(calls[0].init.body)).get("assertion")!;