From 82a95593bdc4b7ef0a5119d17996e1bc028310f1 Mon Sep 17 00:00:00 2001 From: Lilleman auf Larv Date: Tue, 1 Sep 2026 19:16:21 +0200 Subject: [PATCH] Refuse to answer a message whose link went, instead of reporting it delivered --- README.md | 4 +++ src/dlr-merger.ts | 4 +-- src/expiring-groups.ts | 7 +++++- src/held-messages.ts | 11 ++++++++- src/incoming-requests.ts | 1 + src/reassembly.ts | 2 +- src/sms.ts | 11 ++++++++- test/session-extras.test.ts | 49 +++++++++++++++++++++++++++++++++++++ todo.md | 7 +----- 9 files changed, 84 insertions(+), 12 deletions(-) diff --git a/README.md b/README.md index 51acdc6..cb67bf3 100644 --- a/README.md +++ b/README.md @@ -355,6 +355,10 @@ so it fails, and `sendSms()` and `sms.sendDlr()` count it in `unanswered`, wheth under it, the peer never answered in time, or you aborted it after it went out. Neither applies with `reconnect: false`, where a drop ends the session and every send after it is refused. +An answer cannot wait for a link that way, because it carries the sequence number the message arrived +on: `sms.sendResp()` on a message whose link dropped writes nothing and returns an `err`. Its +`sms.sendDlr()` still goes out, since a receipt is a request of its own, correlated by the id it names. + `responseTimeout` bounds the wait for a link and the wait for an answer separately, and a send also queues for a `maxOutstanding` slot, which nothing bounds — so it is not a deadline for the call. Pass `{ signal: AbortSignal.timeout(ms) }` when you need one. diff --git a/src/dlr-merger.ts b/src/dlr-merger.ts index 71d30a6..678ad10 100644 --- a/src/dlr-merger.ts +++ b/src/dlr-merger.ts @@ -120,8 +120,8 @@ export class DlrMerger { } clear(): void { - this.groups.clear(); - this.spent.clear(); + this.groups.takeAll(); + this.spent.takeAll(); } /** Drops every group past its deadline. Runs before each collect and on its own timer. */ diff --git a/src/expiring-groups.ts b/src/expiring-groups.ts index 584a1a2..3a25d89 100644 --- a/src/expiring-groups.ts +++ b/src/expiring-groups.ts @@ -58,9 +58,14 @@ export class ExpiringGroups { this.idle(); } - clear(): void { + /** Removes every group and hands them over. */ + takeAll(): [string, T][] { + const taken: [string, T][] = [...this.entries].map(([key, entry]) => [key, entry.group]); + this.entries.clear(); this.idle(); + + return taken; } /** Removes every group past its deadline and hands them over. */ diff --git a/src/held-messages.ts b/src/held-messages.ts index 0a2a665..3324784 100644 --- a/src/held-messages.ts +++ b/src/held-messages.ts @@ -20,6 +20,7 @@ function keyOf(pduObjs: PduObject[]): string | undefined { /** The messages handed to the application that it has not answered yet, held by their segments. */ export class HeldMessages { + private readonly droppedWithLink = new WeakSet(); private readonly held: ExpiringGroups; private readonly idleWaiters = new IdleWaiters(); private readonly log: SmppLog; @@ -64,6 +65,11 @@ export class HeldMessages { return key !== undefined && this.held.get(key) === pduObjs; } + /** Whether this message's link went before it was answered, so no answer of ours correlates. */ + lostLink(pduObjs: PduObject[]): boolean { + return this.droppedWithLink.has(pduObjs); + } + release(pduObjs: PduObject[]): void { const key = keyOf(pduObjs); @@ -76,7 +82,10 @@ export class HeldMessages { /** Drops every message: their segments went with the link, so no answer of ours correlates now. */ clear(): void { - this.held.clear(); + for (const [, pduObjs] of this.held.takeAll()) { + this.droppedWithLink.add(pduObjs); + } + this.idleWaiters.settle(); } diff --git a/src/incoming-requests.ts b/src/incoming-requests.ts index 202f3af..0487401 100644 --- a/src/incoming-requests.ts +++ b/src/incoming-requests.ts @@ -170,6 +170,7 @@ export class IncomingRequests { session: this.session, to: paramText(first.params.destination_addr), }, { + lostLink: () => this.held.lostLink(pduObjs), // A turn later, so a listener sending its receipt straight after the response still holds. onAnswered: () => { setImmediate(() => { this.held.release(pduObjs); }); }, // Past the refusal only while a drain is still waiting for this message; an ordinary send after. diff --git a/src/reassembly.ts b/src/reassembly.ts index efc5e2e..59b1634 100644 --- a/src/reassembly.ts +++ b/src/reassembly.ts @@ -163,7 +163,7 @@ export class Reassembler { } clear(): void { - this.groups.clear(); + this.groups.takeAll(); this.octets = 0; } diff --git a/src/sms.ts b/src/sms.ts index a93cf6f..8f8f847 100644 --- a/src/sms.ts +++ b/src/sms.ts @@ -54,6 +54,8 @@ export type SmsInput = { /** What the session's incoming side gives a message so it can be answered and accounted for. */ export type SmsHandlers = { + /** Whether the link this message arrived on is gone, so no answer of ours correlates. */ + lostLink: () => boolean; onAnswered: () => void; send: (input: PduObjectInput) => Promise>; }; @@ -76,7 +78,8 @@ export function createSms(input: SmsInput, handlers: SmsHandlers): Sms { message: input.message, pduObjs: input.pduObjs, sendDlr: status => sendDlr(sms, handlers.send, status), - sendResp: options => sendResp(sms, answered, options ?? {}).finally(handlers.onAnswered), + sendResp: options => sendResp(sms, answered, options ?? {}, handlers.lostLink) + .finally(handlers.onAnswered), session: input.session, get smsId(): string { return answered.smsId; @@ -92,6 +95,7 @@ async function sendResp( sms: Sms, answered: { smsId: string }, options: SendRespOptions, + lostLink: () => boolean, ): Promise { const total = sms.pduObjs.length; @@ -103,6 +107,11 @@ async function sendResp( return { err: new Error('smsId must not be empty') }; } + // A response carries the sequence number it was asked on, which the next link knows nothing about. + if (lostLink()) { + return { err: new Error('The link this message arrived on is gone, so nothing would correlate the response') }; + } + if (options.smsId !== undefined) answered.smsId = options.smsId; const results = await Promise.all(sms.pduObjs.map((pduObj, index) => sms.session.sendReturn( diff --git a/test/session-extras.test.ts b/test/session-extras.test.ts index 91c41be..087deec 100644 --- a/test/session-extras.test.ts +++ b/test/session-extras.test.ts @@ -557,6 +557,40 @@ describe('reconnect', () => { assert.equal(report.segments.length, 3); }); + test('refuses to answer a message whose link went, rather than reporting it delivered', async t => { + const smpp = await startServer(t); + const { session } = await connect(t, smpp, { reconnect: { maxDelay: 100, minDelay: 20 } }); + + assert.ok(session); + + const arrived = once(resolve => { session.on('sms', resolve); }); + + void peerOf(smpp).send({ + cmdName: 'deliver_sm', + params: { + destination_addr: '46701113311', + short_message: 'answered too late', + source_addr: '46709771337', + }, + }); + + const sms = await arrived; + const reconnected = once(resolve => { session.on('reconnected', () => { resolve(true); }); }); + + await peerOf(smpp).close({ signal: AbortSignal.abort() }); + await reconnected; + + const answered = await sms.sendResp(); + + assert.match(answered.err?.message ?? '', /link this message arrived on is gone/); + + // A receipt is a request of its own, correlated by its id, so the new link carries it. + const report = await sms.sendDlr('DELIVERED'); + + assert.equal(report.err, undefined); + assert.equal(report.pduObjs.length, 1); + }); + test('does not reconnect after an explicit close', async t => { const smpp = await startServer(t); const { session } = await connect(t, smpp, { reconnect: { maxDelay: 50, minDelay: 10 } }); @@ -913,6 +947,20 @@ describe('held message bounds', () => { held.clear(); }); + test('remembers which messages went with the link, and which were answered', () => { + const held = new HeldMessages({ log: silentLog, max: 10, timeout: 10_000 }); + const answered = message(1); + const dropped = message(2); + + held.hold(answered); + held.hold(dropped); + held.release(answered); + held.clear(); + + assert.equal(held.lostLink(dropped), true); + assert.equal(held.lostLink(answered), false); + }); + // Without this the drain sits out its whole budget before returning what a sweep already settled. test('wakes a waiting drain when the last message expires', async () => { let now = 0; @@ -944,6 +992,7 @@ describe('sendDlr()', () => { session, to: '46709771337', }, { + lostLink: () => false, onAnswered: () => undefined, send: () => { call++; diff --git a/todo.md b/todo.md index 1f1cacb..b495093 100644 --- a/todo.md +++ b/todo.md @@ -60,6 +60,7 @@ Rules the API follows: | `OutgoingRequests`: the gate, the window, the pending map and the retry under one owner, told when a link comes up or goes down | `test/session-extras.test.ts`, `test/session.test.ts` | | Held messages capped and expiring, so an application that answers nothing cannot grow them | `test/session-extras.test.ts` | | A send with no link held for the next one, and one the link dropped under counted as `unanswered` | `test/session-extras.test.ts` | +| A message whose link dropped refused an answer, with its receipt still allowed out | `test/session-extras.test.ts` | | Every runnable README example | `test/readme.test.ts` | | Receipt-versus-message classification by `esm_class` | `test/dlr.test.ts`, `test/session.test.ts` | | A listener that throws, or rejects, reaching `sessionError`/`serverError` rather than the process | `test/session.test.ts`, `test/error-from.test.ts` | @@ -140,12 +141,6 @@ session message is a change to every call site. until the message expires. Same cost as the `onRequest`-answers-nothing case that was declined, but reached by a bug rather than a policy. Raised by review, 2026-09-01. -- [ ] **A message the reconnect dropped is answered into the void, and reported as delivered.** - `teardown()` clears the held messages along with the inbound segments, which is right — but the - application still holds the `Sms`, so `sendResp()` writes the old link's sequence numbers to the - new socket, succeeds, and returns `{}` for a response that correlates with nothing at the peer. - `HeldMessages` now knows exactly which messages went that way, so saying so is a small - addition. Goal 2, low frequency. Raised by review, 2026-09-01. - [ ] **Does an intermediate delivery notification deserve to be a `dlr`?** `esm_class` message type `INTERMEDIATE_DELIVERY` (0x20) is classified as a message today, so a peer that reports non-final states with it hands the application a raw `id:… stat:ENROUTE` text as an inbound