diff --git a/AGENTS.md b/AGENTS.md index d791e9d..8e083bc 100644 --- a/AGENTS.md +++ b/AGENTS.md @@ -307,6 +307,11 @@ Grouped by what each one constrains. shutdown emits `close`. A retry that opens a socket and then loses it clears `closed` through `attach()`, which is why a second drop emits again. +- **An answer belongs to the link the message arrived on; a receipt does not.** Maintainer's call, + 2026-09-01. Rejected: answering on the new link, which succeeds and reports `{}` for a response + that correlates with nothing — goal 2's wrong answer. Accepted: a receipt sent after a refused + response names an id the peer has no record of. + - **`reconnect` takes `{ minDelay, maxDelay }` to retune and `false` to turn off**, so absent means on and there is one spelling for each. Only `client()` reconnects — a `server()` session is a connection the peer opened, and nothing at this end can reopen it. The retry timer is `unref()`'d, diff --git a/README.md b/README.md index 51acdc6..48108aa 100644 --- a/README.md +++ b/README.md @@ -316,7 +316,7 @@ TypeScript users can import `SmppLog` to have the compiler check one. | Event | Fires when | | --- | --- | -| `sms` | An SMS arrives, reassembled if it was multipart. Carries `sendResp()`, `sendDlr()` and the `smsId` it was answered with. | +| `sms` | An SMS arrives, reassembled if it was multipart. Carries `sendResp()`, `sendDlr()` and its `smsId`. | | `dlr` | A delivery report arrives, one per segment. `smsId` is undefined when the peer marked a receipt whose body carries no readable id. `statusMsg` names `statusId` unless the peer sent a `message_state` this library cannot name — then `statusId` is that raw value and `statusMsg` is whatever the body said, or `UNKNOWN`. | | `messageDlr` | Every segment of a multipart message sent with `dlr: true` has been reported on, carrying the worst status of the segments. Merging needs the SMSC to number its segment ids `-`, which is this library's own server's convention — an SMSC that hands out unrelated ids per segment never fires it. A base is merged once: a later message the SMSC gives the same ids is reported on through `dlr` alone, and an earlier one still collecting loses its merged report as well. | | `close` | The session is over, because nothing will bring the link back. Fires once, whether you closed it or the link failed for good. | @@ -355,6 +355,11 @@ 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`. Where a +reconnect follows, its `sms.sendDlr()` still goes out on the new link, 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. @@ -394,7 +399,8 @@ The spec tables are exported both individually (`cmds`, `consts`, `encodings`, ` - **`server()` resolves once, when it is listening**, and gives you a handle with `close()`, `port` and a `session` event. It no longer calls your callback once per incoming connection. - **The id a message is answered with goes to `sendResp({ smsId })`**, and `sms.smsId` is read-only: - it reports what the response actually carried. Delete any `sms.smsId = …` line — assigning to it + it reports the id `sendResp()` was given, or the UUID v7 generated instead. Delete any + `sms.smsId = …` line — assigning to it throws a `TypeError`, since modules are always strict mode — and pass the id to `sendResp()`. - **`checkuserpass` is now `authenticate`**, takes `{ password, session, systemId, systemType }` and returns `false` or `{ userData }`. diff --git a/src/incoming-requests.ts b/src/incoming-requests.ts index 202f3af..547015a 100644 --- a/src/incoming-requests.ts +++ b/src/incoming-requests.ts @@ -39,6 +39,7 @@ export class IncomingRequests { private readonly session: Session; private readonly smsIdFormat: SmsIdFormat; private readonly systemId: string; + private linkGeneration = 0; constructor(options: IncomingRequestsOptions) { this.dlrMerger = options.dlrMerger; @@ -62,8 +63,17 @@ export class IncomingRequests { } async handle(pduObj: PduObject): Promise { + const generation = this.linkGeneration; + if (this.onRequest && await this.onRequest(this.session, pduObj)) return; + // The link it arrived on went while the hook ran, so nothing we answer now correlates. + if (this.linkGeneration !== generation) { + this.log.info('session - dropping a request whose link went', { cmdName: pduObj.cmdName }); + + return; + } + if (!this.session.bindAllows(pduObj.cmdName)) { this.log.info('session - command the peer\'s bind direction does not carry', { bindType: this.session.boundAs ?? '', @@ -96,6 +106,7 @@ export class IncomingRequests { /** Drops the segments of every message that never became whole, and of every one still held. */ clear(): void { + this.linkGeneration++; this.held.clear(); this.reassembler.clear(); } @@ -163,6 +174,8 @@ export class IncomingRequests { if (!first) return; + const generation = this.linkGeneration; + const sms = createSms({ from: paramText(first.params.source_addr), message: decodeSegments(pduObjs), @@ -170,6 +183,7 @@ export class IncomingRequests { session: this.session, to: paramText(first.params.destination_addr), }, { + lostLink: () => this.linkGeneration !== generation, // 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/sms.ts b/src/sms.ts index a93cf6f..8b74b1d 100644 --- a/src/sms.ts +++ b/src/sms.ts @@ -38,7 +38,7 @@ export type Sms = { /** Answers every segment. Part of the protocol, not optional. Defaults to ESME_ROK. */ sendResp: (options?: SendRespOptions) => Promise; session: Session; - /** The id answered to the peer: what sendResp() was given, or a generated UUID v7. */ + /** The id `sendResp()` was given, or a generated UUID v7. */ readonly smsId: string; submitTime: Date; to: string; @@ -54,6 +54,7 @@ export type SmsInput = { /** What the session's incoming side gives a message so it can be answered and accounted for. */ export type SmsHandlers = { + lostLink: () => boolean; onAnswered: () => void; send: (input: PduObjectInput) => Promise>; }; @@ -76,7 +77,8 @@ 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 +94,7 @@ async function sendResp( sms: Sms, answered: { smsId: string }, options: SendRespOptions, + lostLink: () => boolean, ): Promise { const total = sms.pduObjs.length; @@ -105,6 +108,11 @@ async function sendResp( if (options.smsId !== undefined) answered.smsId = options.smsId; + // 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') }; + } + const results = await Promise.all(sms.pduObjs.map((pduObj, index) => sms.session.sendReturn( pduObj, options.status ?? 'ESME_ROK', diff --git a/test/session-extras.test.ts b/test/session-extras.test.ts index 91c41be..1608de2 100644 --- a/test/session-extras.test.ts +++ b/test/session-extras.test.ts @@ -13,6 +13,7 @@ import type { Sms } from '../src/sms.ts'; import type { SmppServer } from '../src/server.ts'; import type { TestContext } from 'node:test'; import { HeldMessages } from '../src/held-messages.ts'; +import { IncomingRequests } from '../src/incoming-requests.ts'; import { UnansweredError } from '../src/unanswered-error.ts'; import { createSms } from '../src/sms.ts'; import { LinkGate } from '../src/link-gate.ts'; @@ -557,6 +558,88 @@ describe('reconnect', () => { assert.equal(report.segments.length, 3); }); + test('refuses to answer a message whose link went, held or already answered', async t => { + const smpp = await startServer(t); + const { session } = await connect(t, smpp, { reconnect: { maxDelay: 100, minDelay: 20 } }); + + assert.ok(session); + + const arrived: Sms[] = []; + const both = once(resolve => { + session.on('sms', sms => { + arrived.push(sms); + + if (arrived.length === 2) resolve(true); + }); + }); + + for (const text of ['answered before the drop', 'never answered']) { + void peerOf(smpp).send({ + cmdName: 'deliver_sm', + params: { + destination_addr: '46701113311', + short_message: text, + source_addr: '46709771337', + }, + }); + } + + await both; + + const [answered, held] = arrived; + + assert.ok(answered); + assert.ok(held); + assert.equal(answered.message, 'answered before the drop'); + assert.equal((await answered.sendResp()).err, undefined); + + const reconnected = once(resolve => { session.on('reconnected', () => { resolve(true); }); }); + + await peerOf(smpp).close({ signal: AbortSignal.abort() }); + await reconnected; + + let taken = 0; + + // A response is dispatched before `incomingPduObj`, so only the raw event sees one arrive. + peerOf(smpp).on('incomingPdu', () => { taken++; }); + + assert.match((await answered.sendResp()).err?.message ?? '', /link this message arrived on is gone/); + assert.match((await held.sendResp()).err?.message ?? '', /link this message arrived on is gone/); + + assert.equal((await held.sendDlr('DELIVERED')).err, undefined); + assert.equal(taken, 1, 'a refused response reached the new link'); + }); + + test('drops a message whose link went while onRequest was still running', async t => { + const session = new Session({ sock: new net.Socket() }); + + closeAfter(t, session); + session.boundAs = 'transceiver'; + + const incoming = new IncomingRequests({ + dlrMerger: new DlrMerger({ log: silentLog, max: 10, timeout: 10_000 }), + log: silentLog, + onRequest: async () => { await delay(10); return false; }, + sendPastDrain: () => Promise.resolve({ err: new Error('never sent') }), + session, + }); + let messages = 0; + + session.on('sms', () => { messages++; }); + + const handled = incoming.handle(submitPdu(1)); + + incoming.clear(); + + await handled; + + assert.equal(messages, 0); + + await incoming.handle(submitPdu(2)); + + assert.equal(messages, 1, 'the harness delivers a message whose link stayed'); + }); + 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 } }); @@ -944,6 +1027,7 @@ describe('sendDlr()', () => { session, to: '46709771337', }, { + lostLink: () => false, onAnswered: () => undefined, send: () => { call++; diff --git a/todo.md b/todo.md index 8353602..7762c37 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 +141,11 @@ 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. +- [ ] **A refused `sendResp()` releases the hold anyway.** Every early return runs + `.finally(onAnswered)`, so `sendResp({ smsId: '' })` refuses and stops the drain waiting for a + message the peer was never answered, which `close()` then reports as answered. 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