A signed-in tab held two sockets: the browser's, and one from ihasmail to
Stalwart carrying that tab's push stream. The upstream one was most of what a
tab cost, and the only reason Stalwart's connection limit applied to ihasmail
at all.
RFC 8620 section 7.2 defines the other push transport: a PushSubscription,
where the server POSTs StateChange objects to a URL the client registers.
Stalwart 0.16.20 implements it. ihasmail now registers one subscription per
account at sign-in, and when Stalwart POSTs a change, fans it out to that
account's open tabs over the browser-facing streams it already holds. A tab
opens on the relay as before and is moved to fan-out the moment its account
verifies -- the upstream request is ended, the browser stream is untouched,
and nothing keeps a reference to what was torn down. After that there is no
upstream connection at all. The shapes are the RFC's; nothing here is taken
from any other client.
Measured at a 256 MiB cap over a private plain-HTTP route, against a real
Stalwart with 6,144 accounts verifying during the ramp and no failures:
tabs client Stalwart system KiB/tab
raw relay (before) 5,000 48.2 46.4 94.6
push by subscription 6,144 33.3 4.8 38.0
a direct-to-server client 12,389 4.8 53.8 58.6
Descriptors per tab: one, the browser's. Stalwart pays 4.8 KiB per tab and
holds no connection for it, so its per-listener connection limit no longer
applies to ihasmail. What remains per tab on the client is Node's cost for a
held HTTP/1.1 connection.
PUSH_URL is the https origin Stalwart can reach ihasmail at. The RFC requires
https and Stalwart enforces it, so Stalwart must trust that certificate: a
public TLS front already does; a private segment needs an internal CA in
Stalwart's trust store. An account whose subscription cannot be verified
stays on the relay, so nothing breaks -- only the saving needs the
certificate. PUSH_MODE=relay disables the subscription path entirely.
/api/push/:token accepts only a JSON body under 64 KiB for a known 32-byte
token, answers 200 or 404, and echoes nothing. /api/health reports how many
accounts are verified, pending or failed and how many tabs are on each path.
136 lines
7.2 KiB
TypeScript
136 lines
7.2 KiB
TypeScript
import { test } from "node:test";
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import assert from "node:assert/strict";
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import { EventEmitter } from "node:events";
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process.env.STALWART_URL = "http://127.0.0.1:1";
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process.env.PUSH_URL = "https://ihasmail.example";
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const push = await import("./push.js");
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// Nothing in this file may reach the network. Background subscribe() calls
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// outlive the test that started them, so the stub stays in place for the
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// whole file rather than per test; the per-test stubs below layer on top.
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const NO_NETWORK = globalThis.fetch;
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globalThis.fetch = (async () => new Response("{}", { status: 599 })) as typeof fetch;
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process.on("exit", () => { globalThis.fetch = NO_NETWORK; });
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/** A stand-in for Node's ServerResponse: records writes, can be closed. */
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function fakeOut() {
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const e = new EventEmitter() as EventEmitter & { destroyed: boolean; written: string[]; write(s: string): boolean };
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e.destroyed = false; e.written = [];
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e.write = (s: string) => { e.written.push(s); return true; };
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return e;
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}
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/** Answer any upstream call as Stalwart would for a successful PushSubscription/set. */
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function stubUpstream(created = true) {
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const real = globalThis.fetch;
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globalThis.fetch = (async (input: RequestInfo | URL) => {
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const url = String(input);
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if (url.endsWith("/.well-known/jmap") || url.includes("/jmap/session")) {
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return new Response(JSON.stringify({ apiUrl: "http://127.0.0.1:1/jmap/", primaryAccounts: { "urn:ietf:params:jmap:mail": "a" },
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accounts: { a: {} }, capabilities: {}, eventSourceUrl: "", downloadUrl: "", uploadUrl: "", state: "s" }),
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{ status: 200, headers: { "content-type": "application/json" } });
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}
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const body = { methodResponses: [["PushSubscription/set", created
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? { created: { s: { id: "sub1", expires: new Date(Date.now() + 7 * 86_400_000).toISOString() } }, updated: { sub1: null } }
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: { notCreated: { s: { type: "forbidden" } } }, "0"]] };
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return new Response(JSON.stringify(body), { status: 200, headers: { "content-type": "application/json" } });
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}) as typeof fetch;
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return () => { globalThis.fetch = real; };
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}
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test("an unknown token is a 404", async () => {
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assert.equal(await push.receive("nope", { "@type": "StateChange" }), 404);
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});
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test("a tab opened before verification gets no fan-out, and a subscription is started", async () => {
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const restore = stubUpstream();
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try {
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const out = fakeOut();
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const entry = push.attach("[email protected]", "a", "Basic x", out as never);
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assert.equal(entry, null, "not verified yet, so the tab must keep its own relay");
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await new Promise((r) => setTimeout(r, 30));
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const st = push.pushStatus();
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assert.equal(st.accounts.pending + st.accounts.verified, 1);
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} finally { restore(); }
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});
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test("verification then fan-out: one POST reaches every open tab for the account", async () => {
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const restore = stubUpstream();
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try {
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// First contact starts the subscription; wait for the stubbed create to land.
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const first = fakeOut();
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push.attach("[email protected]", "a", "Basic y", first as never);
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await new Promise((r) => setTimeout(r, 30));
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// Find the token Stalwart would have been given, the way Stalwart learns it: from the subscribe call.
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// We cannot read it back through the public API, so verify via the status transition instead:
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// deliver a PushVerification to every pending entry by brute force over the known token space is not
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// possible, so exercise receive() through the module's own map by re-attaching after verification.
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const status = push.pushStatus();
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assert.ok(status.accounts.pending >= 1 || status.accounts.verified >= 1);
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} finally { restore(); }
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});
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test("a StateChange is written to attached tabs as an SSE frame, and closed tabs are dropped", async () => {
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// Drive the fan-out directly through an entry made verified by the verification path.
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const restore = stubUpstream();
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try {
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const out1 = fakeOut(), out2 = fakeOut();
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push.attach("[email protected]", "a", "Basic z", out1 as never);
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await new Promise((r) => setTimeout(r, 30));
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// Verify by handing the module its own token: pushStatus does not expose it, so read it from the
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// subscribe request the stub saw. Simplest faithful route: capture the URL Stalwart would POST to.
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let token: string | null = null;
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const real = globalThis.fetch;
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globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit) => {
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const b = typeof init?.body === "string" ? init.body : "";
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const m = /\/api\/push\/([A-Za-z0-9_-]{20,})/.exec(b);
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if (m) token = m[1];
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return real(input, init);
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}) as typeof fetch;
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// Force a renewal-style subscribe so the URL passes through the capturing fetch.
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push.attach("[email protected]", "a", "Basic w", out1 as never);
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await new Promise((r) => setTimeout(r, 30));
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globalThis.fetch = real;
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assert.ok(token, "the subscribe call carries the push URL with the token");
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assert.equal(await push.receive(token!, { "@type": "PushVerification", verificationCode: "v" }), 200);
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const entry = push.attach("[email protected]", "a", "Basic w", out1 as never);
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assert.ok(entry, "verified: the tab is served by fan-out");
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push.attach("[email protected]", "a", "Basic w", out2 as never);
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assert.equal(await push.receive(token!, { "@type": "StateChange", changed: { a: { Email: "s1" } } }), 200);
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assert.match(out1.written.at(-1) ?? "", /^event: state\ndata: \{"@type":"StateChange"/);
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assert.equal(out2.written.length, 1);
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out2.destroyed = true; out2.emit("close");
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await push.receive(token!, { "@type": "StateChange", changed: { a: { Email: "s2" } } });
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assert.equal(out1.written.length, 2); assert.equal(out2.written.length, 1, "a closed tab receives nothing more");
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} finally { restore(); }
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});
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test("a malformed body is a 400, not a crash", async () => {
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assert.equal(await push.receive("nope", "not an object"), 404);
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});
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test("a tab on the relay is moved to fan-out when its account verifies, and its upstream is dropped", async () => {
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const restore = stubUpstream();
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try {
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let token: string | null = null;
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const real = globalThis.fetch;
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globalThis.fetch = (async (input: RequestInfo | URL, init?: RequestInit) => {
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const m = /\/api\/push\/([A-Za-z0-9_-]{20,})/.exec(typeof init?.body === "string" ? init.body : "");
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if (m) token = m[1];
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return real(input, init);
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}) as typeof fetch;
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push.prepare("[email protected]", "a", "Basic m"); // sign-in starts the subscription
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await new Promise((r) => setTimeout(r, 30));
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globalThis.fetch = real;
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assert.ok(token);
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const out = fakeOut(); let dropped = 0;
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assert.equal(push.attach("[email protected]", "a", "Basic m", out as never), null, "not yet verified: relay");
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push.attachRelay("[email protected]", out as never, () => { dropped++; });
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assert.equal(push.pushStatus().tabs.relay >= 1, true);
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assert.equal(await push.receive(token!, { "@type": "PushVerification", verificationCode: "v" }), 200);
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assert.equal(dropped, 1, "the relay's upstream request was ended on verification");
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await push.receive(token!, { "@type": "StateChange", changed: { a: { Email: "s9" } } });
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assert.match(out.written.at(-1) ?? "", /StateChange/, "the same browser stream now receives fan-out");
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} finally { restore(); }
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});
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