Enforce bind direction, cap segments per message and pin the README examples

AGENTS.md

@@ -55,7 +55,7 @@ src/
 	result.ts            Result<T> — the shape every fallible call returns
 	send-sms.ts          submitSms composition and the submitSmParams builder
 	send-window.ts       SendWindow: the maxOutstanding semaphore
-	session-options.ts   SessionOptions, ReconnectOptions and the session defaults
+	session-options.ts   SessionOptions, ReconnectOptions, bind direction and the session defaults
 	udh.ts               User data header: the concatenation fields of a long SMS
 	uuid.ts              uuidv7() — the ids the library generates for messages
 	defs/
@@ -185,6 +185,13 @@ exactly 140.
   `server()`, so an implementation that needs 5.0 throughout can have it. The threshold at or above
   which a peer may be sent optional parameters is fixed at 0x34 by the spec and is not the same
   constant as the declared version.
+- **Bind direction is enforced on the library's own senders and on everything incoming, not on
+  `send()`.** A receiver-bound ESME carries no `submit_sm` and a transmitter-bound one no
+  `deliver_sm`; `sendSms()` and `sendDlr()` refuse locally, and an arriving PDU is answered
+  `ESME_RINVBNDSTS`. `bindAllows()` is a predicate on the same footing as `acceptsOptionalParams()`,
+  so the deliberately public low-level `send()` stays a passthrough. Only those two commands are
+  policed, because they are the only ones the library sends and dispatches by direction.
+
 - **The logger is a five-method contract this library declares, not a dependency.** `SmppLog` in
   `log.ts` is what the code actually calls (`debug`, `error`, `info`, `verbose`, `warn`), so an
   application can satisfy it with an object literal and `@larvit/smpp` ships with no runtime

README.md

@@ -92,16 +92,24 @@ Every one is optional.
 ```javascript
 await session.sendSms({
 	dlr:                  true,        // ask for a delivery report
+	destinationAddrNpi:   0,           // override the numbering plan of the recipient
+	destinationAddrTon:   1,
 	encoding:             'UCS2',      // override the automatic choice
 	flash:                false,
 	from:                 'MyBrand',   // alphanumeric -> TON 5, digits -> TON 1
+	maxSegments:          10,          // refuse a longer message instead of sending it
 	message:              'Hello world',
 	scheduleDeliveryTime: new Date(Date.now() + 3600_000),
+	sourceAddrNpi:        0,           // override the numbering plan of the sender
+	sourceAddrTon:        5,
 	to:                   '46709771337',
 	validityPeriod:       3600,        // seconds, or a Date
 }, { signal });                       // optional per-call AbortSignal
 ```
 
+`sourceAddrTon` and `destinationAddrTon` default to 5 for an alphanumeric address and 1 for a
+numeric one; the NPI fields default to 0. Set them for an operator that requires something else.
+
 Messages too long for one SMS are split automatically and sent as a concatenated message. You get
 one id per segment:
 
@@ -113,7 +121,8 @@ const { err, pduObjs, smsIds } = await session.sendSms({ from, message, to });
 segment goes on the wire together, `pduObjs` and `smsIds` then hold what the SMSC did accept — enough
 to reconcile against a later receipt, not enough to resend the rest, so treat a partial failure as a
 failed message. A message needing more than 255 segments is refused before anything is sent, since
-the concatenation header numbers segments in a single octet.
+the concatenation header numbers segments in a single octet. `maxSegments` lowers that ceiling:
+most handsets and SMSCs stop well short of 255, and refusing beats a message only half delivered.
 
 ### Receiving
 
@@ -143,6 +152,7 @@ if (err) throw err;
 smpp.on('session', session => {
 	session.on('sms', async sms => {
 		// sms.from, sms.to, sms.message, sms.dlr
+		await sms.sendResp();
 	});
 });
 ```
@@ -200,6 +210,20 @@ A message whose `data_coding` says 8-bit binary arrives as Latin-1, so `Buffer.f
 | `reassemblyTimeout` | `300000` | How long a late segment can still join an incomplete message. |
 | `responseTimeout`, `maxOutstanding`, `log`, `signal` | as for the client | |
 
+### Bind direction
+
+The three bind types are honoured in both directions, not just accepted. A receiver-bound ESME
+carries no `submit_sm` and a transmitter-bound one is sent no `deliver_sm`, whichever end of the
+link the session is:
+
+- `session.sendSms()` on a receiver-bound session, and `sms.sendDlr()` to a transmitter-bound peer,
+  fail with an `err` before anything reaches the wire.
+- A `submit_sm` arriving on a receiver-bound session, or a `deliver_sm` on a transmitter-bound one,
+  is answered `ESME_RINVBNDSTS`.
+
+A `transceiver` bind, the default, carries both. `session.send()` stays a low-level passthrough and
+is not checked, so the raw surface can still put whatever a test or a proxy needs on the wire.
+
 ## Errors
 
 Nothing in this library throws. Every fallible call returns a result carrying an optional `err`, so
@@ -278,6 +302,9 @@ at and above which the spec allows optional parameters to be sent to it; `peerIn
 the version it declared, `0x00` if it declared none. The library's own senders consult the first before attaching a TLV — a
 `send()` you build yourself is passed through as written, so consult it too when you attach TLVs.
 
+`bindAllows(cmdName)` answers the same question for the bind direction, and `boundAs` is the role
+the ESME bound with — see [Bind direction](#bind-direction).
+
 ## Working with PDUs directly
 
 The codec is exported, synchronous, and never throws — handy for inspecting captured traffic:

eslint.config.js

@@ -48,6 +48,11 @@ export default tseslint.config(
 		files: ['src/defs/encodings.ts'],
 		rules: { 'no-control-regex': 'off' },
 	},
+	{
+		// Mirrors the README's examples as written; an async event listener is part of what they show.
+		files: ['test/readme.test.ts'],
+		rules: { '@typescript-eslint/no-misused-promises': 'off' },
+	},
 	{
 		files: ['eslint.config.js'],
 		extends: [tseslint.configs.disableTypeChecked],

src/client.ts

@@ -1,7 +1,10 @@
 import type { ConnectionOptions } from 'node:tls';
 import type { Result, VoidResult } from './result.ts';
+import type { BindType } from './session-options.ts';
 import type { SmppLog } from './log.ts';
 import type { Socket } from 'node:net';
+export type { BindType };
+
 import { Session } from './session.ts';
 import { checkSessionOptions, undeclaredInterfaceVersion } from './session-options.ts';
 import { connect as netConnect } from 'node:net';
@@ -9,8 +12,6 @@ import { connect as tlsConnect } from 'node:tls';
 import { defaultInterfaceVersion } from './defs/constants.ts';
 import { silentLog } from './log.ts';
 
-export type BindType = 'receiver' | 'transceiver' | 'transmitter';
-
 export type ClientOptions = {
 	addressRange?: string;
 	addrNpi?: number;
@@ -125,6 +126,7 @@ async function bind(session: Session, options: ClientOptions): Promise<VoidResul
 
 	const declared = sent.pduObj.tlvs.sc_interface_version?.tagValue;
 
+	session.boundAs = bindType;
 	session.loggedIn = true;
 	session.peerInterfaceVersion = typeof declared === 'number'
 		? declared

src/incoming-requests.ts

@@ -48,6 +48,16 @@ export class IncomingRequests {
 	async handle(pduObj: PduObject): Promise<void> {
 		if (this.onRequest && await this.onRequest(this.session, pduObj)) return;
 
+		if (!this.session.bindAllows(pduObj.cmdName)) {
+			this.log.info('session - command the peer\'s bind direction does not carry', {
+				bindType: this.session.boundAs ?? '',
+				cmdName: pduObj.cmdName,
+			});
+			await this.session.sendReturn(pduObj, 'ESME_RINVBNDSTS');
+
+			return;
+		}
+
 		switch (pduObj.cmdName) {
 			case 'deliver_sm':
 				await this.onDeliverSm(pduObj);

src/send-sms.ts

@@ -15,6 +15,8 @@ export type SendSmsOptions = {
 	encoding?: EncodingName;
 	flash?: boolean;
 	from: string;
+	/** Refuse before sending anything if the message needs more than this many segments. */
+	maxSegments?: number;
 	message: string;
 	scheduleDeliveryTime?: Date | number | string;
 	sourceAddrNpi?: number;
@@ -79,31 +81,26 @@ export function submitSmParams(
 }
 
 /** Puts a message on the wire as one submit_sm per segment. */
-export async function submitSms(deps: SendSmsDeps, sms: SendSmsOptions): Promise<SendSmsResult> {
-	const encoding = sms.encoding ?? detect(sms.message);
-	const segments = splitMessage(sms.message, { encoding, reference: deps.reference });
-
-	if (segments.length === 0) {
-		return {
-			err: new Error(`Message needs more than ${String(maxSegments)} segments, the concatenation limit`),
-			pduObjs: [],
-			smsIds: [],
-		};
+/** Nothing goes on the wire until the whole message fits: a half-sent message bills twice. */
+function checkSegments(allowed: number, segments: number): Error | undefined {
+	if (!Number.isInteger(allowed) || allowed < 1 || allowed > maxSegments) {
+		return new Error(`maxSegments must be between 1 and ${String(maxSegments)}, got ${String(allowed)}`);
 	}
 
-	const multipart = segments.length > 1;
+	if (segments === 0) {
+		return new Error(`Message needs more than ${String(maxSegments)} segments, the concatenation limit`);
+	}
+
+	if (segments > allowed) {
+		return new Error(`Message needs ${String(segments)} segments, more than the ${String(allowed)} allowed`);
+	}
+
+	return undefined;
+}
+
+function collectSent(sent: Result<{ pduObj: PduObject }>[]): SendSmsResult {
 	const pduObjs: PduObject[] = [];
 	const smsIds: string[] = [];
-
-	deps.log.debug('sendSms() - sending', { encoding, segments: segments.length, to: sms.to });
-
-	// Segments go out together rather than one-after-a-response: a receiver that waits for every
-	// segment before answering — this library's own server does — would otherwise deadlock.
-	const sent = await Promise.all(segments.map(segment => deps.send({
-		cmdName: 'submit_sm',
-		params: submitSmParams(sms, segment, { encoding, multipart }),
-	})));
-
 	let failure: Error | undefined;
 
 	for (const one of sent) {
@@ -121,3 +118,25 @@ export async function submitSms(deps: SendSmsDeps, sms: SendSmsOptions): Promise
 
 	return failure ? { err: failure, pduObjs, smsIds } : { pduObjs, smsIds };
 }
+
+export async function submitSms(deps: SendSmsDeps, sms: SendSmsOptions): Promise<SendSmsResult> {
+	const allowed = sms.maxSegments ?? maxSegments;
+	const encoding = sms.encoding ?? detect(sms.message);
+	const segments = splitMessage(sms.message, { encoding, reference: deps.reference });
+	const refused = checkSegments(allowed, segments.length);
+
+	if (refused) return { err: refused, pduObjs: [], smsIds: [] };
+
+	const multipart = segments.length > 1;
+
+	deps.log.debug('sendSms() - sending', { encoding, segments: segments.length, to: sms.to });
+
+	// Segments go out together rather than one-after-a-response: a receiver that waits for every
+	// segment before answering — this library's own server does — would otherwise deadlock.
+	const sent = await Promise.all(segments.map(segment => deps.send({
+		cmdName: 'submit_sm',
+		params: submitSmParams(sms, segment, { encoding, multipart }),
+	})));
+
+	return collectSent(sent);
+}

src/server.ts

@@ -5,7 +5,7 @@ import type { Server as TlsServer, TlsOptions } from 'node:tls';
 import type { SmppLog } from './log.ts';
 import { EventEmitter } from 'node:events';
 import { Session, bindCommands, defaultSystemId } from './session.ts';
-import { checkSessionOptions, undeclaredInterfaceVersion } from './session-options.ts';
+import { bindTypeFromCommand, checkSessionOptions, undeclaredInterfaceVersion } from './session-options.ts';
 import { createServer as createNetServer } from 'node:net';
 import { createServer as createTlsServer } from 'node:tls';
 import { defaultInterfaceVersion } from './defs/constants.ts';
@@ -147,6 +147,7 @@ async function acceptBind(
 ): Promise<void> {
 	const declared = pduObj.params.interface_version;
 
+	session.boundAs = bindTypeFromCommand(pduObj.cmdName);
 	session.loggedIn = true;
 	session.peerInterfaceVersion = typeof declared === 'number'
 		? declared

src/session-options.ts

@@ -25,6 +25,28 @@ export const bindCommands: readonly string[] = [
 	'bind_transmitter',
 ];
 
+export type BindType = 'receiver' | 'transceiver' | 'transmitter';
+
+export function bindTypeFromCommand(cmdName: string): BindType | undefined {
+	if (cmdName === 'bind_receiver') return 'receiver';
+	if (cmdName === 'bind_transceiver') return 'transceiver';
+	if (cmdName === 'bind_transmitter') return 'transmitter';
+
+	return undefined;
+}
+
+/**
+ * Whether a bind direction carries a command at all. A receiver-bound ESME submits nothing and a
+ * transmitter-bound one is delivered nothing, whichever end of the link is looking. A session that
+ * has not bound carries everything, since nothing has declared a direction yet.
+ */
+export function bindCarries(bindType: BindType | undefined, cmdName: string): boolean {
+	if (bindType === 'receiver') return cmdName !== 'submit_sm';
+	if (bindType === 'transmitter') return cmdName !== 'deliver_sm';
+
+	return true;
+}
+
 export type SendOptions = { signal?: AbortSignal | undefined };
 
 /**

src/session.ts

@@ -2,7 +2,7 @@ import type { ErrorName } from './defs/errors.ts';
 import type { MessageDlr } from './dlr-merger.ts';
 import type { ParamValue } from './defs/types.ts';
 import type { PduObject, PduObjectInput, TlvInput } from './pdu.ts';
-import type { ReconnectOptions, SendOptions, SessionEvents, SessionOptions } from './session-options.ts';
+import type { BindType, ReconnectOptions, SendOptions, SessionEvents, SessionOptions } from './session-options.ts';
 import type { Result, VoidResult } from './result.ts';
 import type { SendSmsOptions, SendSmsResult } from './send-sms.ts';
 import type { SmppLog } from './log.ts';
@@ -16,7 +16,7 @@ import { PendingRequests } from './pending-requests.ts';
 import { ReconnectLoop } from './reconnect-loop.ts';
 import { SendWindow } from './send-window.ts';
 import { optionalParamsMinVersion } from './defs/constants.ts';
-import { bindCommands, defaultSystemId, defaults } from './session-options.ts';
+import { bindCarries, bindCommands, defaultSystemId, defaults } from './session-options.ts';
 import { isResp, objToPdu, pduReturn, pduToObj } from './pdu.ts';
 import { silentLog } from './log.ts';
 import { submitSms } from './send-sms.ts';
@@ -30,6 +30,7 @@ export type {
 	SessionEvents,
 	SessionOptions,
 };
+export type { BindType };
 export { bindCommands, defaultSystemId };
 
 export class Session extends EventEmitter<SessionEvents> {
@@ -37,6 +38,8 @@ export class Session extends EventEmitter<SessionEvents> {
 	sock: Socket;
 	readonly log: SmppLog;
 
+	/** The role the ESME bound with, whichever end of the link this is. Undefined before any bind. */
+	boundAs: BindType | undefined = undefined;
 	loggedIn = false;
 	/** What the peer declared when binding: 0x00 if it declared none, undefined before any bind. */
 	peerInterfaceVersion: number | undefined = undefined;
@@ -110,6 +113,11 @@ export class Session extends EventEmitter<SessionEvents> {
 		this.resetTimers();
 	}
 
+	/** Whether this session's bind direction carries a command. Consulted by the library's senders. */
+	bindAllows(cmdName: string): boolean {
+		return bindCarries(this.boundAs, cmdName);
+	}
+
 	/** SMPP 3.4 forbids sending optional parameters to a peer that declared an older version. */
 	acceptsOptionalParams(): boolean {
 		return this.peerInterfaceVersion === undefined
@@ -165,6 +173,10 @@ export class Session extends EventEmitter<SessionEvents> {
 	}
 
 	async sendSms(sms: SendSmsOptions, options: SendOptions = {}): Promise<SendSmsResult> {
+		if (!this.bindAllows('submit_sm')) {
+			return { err: new Error('A receiver-bound session does not carry submit_sm'), pduObjs: [], smsIds: [] };
+		}
+
 		const sent = await submitSms({
 			log: this.log,
 			reference: this.nextConcatReference(),

src/sms.ts

@@ -126,6 +126,10 @@ async function sendDlr(
 	sms: Sms,
 	status: MessageState = 'DELIVERED',
 ): Promise<Result<{ pduObjs: PduObject[] }>> {
+	if (!sms.session.bindAllows('deliver_sm')) {
+		return { err: new Error('A transmitter-bound session does not carry deliver_sm') };
+	}
+
 	const total = sms.pduObjs.length;
 	const pduObjs: PduObject[] = [];
 

test/readme.test.ts

@@ -0,0 +1,235 @@
+import assert from 'node:assert/strict';
+import test, { describe } from 'node:test';
+import type { Dlr } from '../src/dlr.ts';
+import type { Session } from '../src/session.ts';
+import type { Sms } from '../src/sms.ts';
+import type { SmppLog } from '../src/log.ts';
+import type { SmppServer } from '../src/server.ts';
+import type { TestContext } from 'node:test';
+import { client } from '../src/client.ts';
+import { server } from '../src/server.ts';
+
+function once<T>(register: (resolve: (value: T) => void) => void): Promise<T> {
+	return new Promise<T>((resolve, reject) => {
+		const timer = setTimeout(() => {
+			reject(new Error('waited 5000 ms for an event that never fired'));
+		}, 5000);
+
+		register(value => {
+			clearTimeout(timer);
+			resolve(value);
+		});
+	});
+}
+
+/** The README's examples listen on the documented default port, so one server runs at a time. */
+async function answeringServer(t: TestContext): Promise<SmppServer> {
+	const { err, server: smpp } = await server();
+
+	assert.equal(err, undefined);
+	assert.ok(smpp);
+	t.after(() => smpp.close());
+
+	smpp.on('session', session => {
+		session.on('sms', async sms => {
+			await sms.sendResp();
+
+			if (sms.dlr) await sms.sendDlr();
+		});
+	});
+
+	return smpp;
+}
+
+describe('README: Client', () => {
+	test('the simplest possible client', async t => {
+		await answeringServer(t);
+
+		const { err, session } = await client();
+		if (err) throw err;
+
+		await session.sendSms({
+			from: '46701113311',
+			message: 'Hello world',
+			to: '46709771337',
+		});
+
+		await session.unbind();
+	});
+
+	test('with connection parameters, a delivery report and logging', async t => {
+		await answeringServer(t);
+
+		const log: SmppLog = {
+			debug: () => undefined,
+			error: () => undefined,
+			info: () => undefined,
+			verbose: () => undefined,
+			warn: () => undefined,
+		};
+
+		const { err, session } = await client({
+			host: 'localhost',
+			log,
+			password: 'bar',
+			port: 2775,
+			username: 'foo',
+		});
+		if (err) throw err;
+
+		t.after(() => { session.close(); });
+
+		const reported = once<Dlr>(resolve => { session.on('dlr', resolve); });
+		const { err: sendErr, smsIds } = await session.sendSms({
+			dlr: true,
+			from: '46701113311',
+			message: '«baff»',
+			to: '46709771337',
+		});
+
+		assert.equal(sendErr, undefined);
+		assert.equal(smsIds.length, 1);
+		assert.equal((await reported).smsId, smsIds[0]);
+	});
+
+	test('the documented sending options', async t => {
+		const smpp = await answeringServer(t);
+		const incoming = once<Sms>(resolve => {
+			smpp.on('session', session => session.on('sms', resolve));
+		});
+		const { err, session } = await client();
+		if (err) throw err;
+
+		t.after(() => { session.close(); });
+
+		const { signal } = new AbortController();
+		const [sms, sent] = await Promise.all([
+			incoming,
+			session.sendSms({
+				dlr: true,
+				encoding: 'UCS2',
+				flash: false,
+				from: 'MyBrand',
+				message: 'Hello world',
+				scheduleDeliveryTime: new Date(Date.now() + 3600_000),
+				to: '46709771337',
+				validityPeriod: 3600,
+			}, { signal }),
+		]);
+
+		assert.equal(sent.err, undefined);
+		assert.equal(sms.from, 'MyBrand');
+		assert.equal(sms.message, 'Hello world');
+	});
+
+	test('receiving an inbound message on a client session', async t => {
+		const smpp = await answeringServer(t);
+		const bound = once<Session>(resolve => { smpp.on('session', resolve); });
+		const { err, session } = await client();
+		if (err) throw err;
+
+		t.after(() => { session.close(); });
+
+		const incoming = once<Sms>(resolve => { session.on('sms', resolve); });
+		const peer = await bound;
+
+		void peer.send({
+			cmdName: 'deliver_sm',
+			params: {
+				destination_addr: '46709771337',
+				short_message: 'inbound hello',
+				source_addr: '46701113311',
+			},
+		});
+
+		const sms = await incoming;
+
+		await sms.sendResp();
+
+		assert.equal(sms.message, 'inbound hello');
+	});
+});
+
+describe('README: Server', () => {
+	test('the simplest possible server', async t => {
+		const { err, server: smpp } = await server();
+		if (err) throw err;
+
+		t.after(() => smpp.close());
+
+		const received: string[] = [];
+
+		smpp.on('session', session => {
+			session.on('sms', async sms => {
+				received.push(sms.message);
+				await sms.sendResp();
+			});
+		});
+
+		const { err: clientErr, session } = await client();
+
+		assert.equal(clientErr, undefined);
+		assert.ok(session);
+
+		await session.sendSms({ from: '46701113311', message: 'Hello world', to: '46709771337' });
+		await session.unbind();
+
+		assert.deepEqual(received, ['Hello world']);
+	});
+
+	test('with authentication and delivery reports', async t => {
+		const { err, server: smpp } = await server({
+			authenticate: ({ password, systemId }) => {
+				if (systemId !== 'foo' || password !== 'bar') return false;
+
+				return { userData: { userId: 123 } };
+			},
+		});
+		if (err) throw err;
+
+		t.after(() => smpp.close());
+
+		smpp.on('session', session => {
+			session.on('sms', async sms => {
+				await sms.sendResp();
+
+				if (sms.dlr) {
+					await sms.sendDlr();
+				}
+			});
+		});
+
+		assert.equal(smpp.port, 2775);
+
+		const refused = await client({ password: 'wrong', username: 'foo' });
+
+		assert.ok(refused.err instanceof Error);
+
+		const { err: clientErr, session } = await client({ password: 'bar', username: 'foo' });
+
+		assert.equal(clientErr, undefined);
+		assert.ok(session);
+
+		const reported = once<Dlr>(resolve => { session.on('dlr', resolve); });
+		const sent = await session.sendSms({
+			dlr: true,
+			from: '46701113311',
+			message: 'with a receipt',
+			to: '46709771337',
+		});
+
+		assert.equal(sent.err, undefined);
+		assert.equal((await reported).statusMsg, 'DELIVERED');
+
+		await session.unbind();
+	});
+});
+
+describe('README: Errors', () => {
+	test('a refused connection reports err instead of throwing', async () => {
+		const { err, session } = await client({ port: 1 });
+
+		assert.ok(err instanceof Error);
+		assert.equal(session, undefined);
+	});
+});

test/session-extras.test.ts

@@ -243,6 +243,31 @@ describe('sendSms()', () => {
 		assert.ok(sent.err instanceof Error);
 		assert.equal(attempts.length, 0);
 	});
+
+	// Most handsets and SMSCs stop well short of the 255 a UDH can number.
+	test('refuses a message needing more segments than the caller allows', async () => {
+		const attempts: PduObjectInput[] = [];
+		const deps = {
+			log: silentLog,
+			reference: 3,
+			send: (input: PduObjectInput) => {
+				attempts.push(input);
+
+				return Promise.resolve({ pduObj: submitResp(attempts.length, `landed-${String(attempts.length)}`) });
+			},
+		};
+		const message = 'a'.repeat(153 * 4);
+
+		const refused = await submitSms(deps, { from: '46701113311', maxSegments: 3, message, to: '46709771337' });
+
+		assert.ok(refused.err instanceof Error);
+		assert.equal(attempts.length, 0);
+
+		const sent = await submitSms(deps, { from: '46701113311', maxSegments: 4, message, to: '46709771337' });
+
+		assert.equal(sent.err, undefined);
+		assert.equal(attempts.length, 4);
+	});
 });
 
 describe('reconnect', () => {

test/session.test.ts

@@ -424,6 +424,93 @@ describe('bind', () => {
 	});
 });
 
+describe('bind direction', () => {
+	// A receiver-bound ESME sends no submit_sm and a transmitter-bound one is sent no deliver_sm.
+	test('refuses a submit_sm from a peer that bound as a receiver', async () => {
+		const smpp = await startServer();
+		const { session } = await connect(smpp, { bindType: 'receiver' });
+
+		assert.ok(session);
+
+		const sent = await session.send({
+			cmdName: 'submit_sm',
+			params: { destination_addr: '46709771337', short_message: 'nope', source_addr: '46701113311' },
+		});
+
+		assert.ok(sent.pduObj);
+		assert.equal(sent.pduObj.cmdStatus, 'ESME_RINVBNDSTS');
+
+		session.close();
+		await smpp.close();
+	});
+
+	test('refuses sendSms() on a receiver-bound session before it reaches the wire', async () => {
+		const smpp = await startServer();
+		const arrived: Sms[] = [];
+
+		smpp.on('session', peer => peer.on('sms', sms => arrived.push(sms)));
+
+		const { session } = await connect(smpp, { bindType: 'receiver' });
+
+		assert.ok(session);
+
+		const sent = await session.sendSms({ from: '46701113311', message: 'nope', to: '46709771337' });
+
+		assert.ok(sent.err instanceof Error);
+		assert.match(sent.err.message, /receiver-bound/);
+		assert.deepEqual(sent.smsIds, []);
+		assert.equal(arrived.length, 0);
+
+		session.close();
+		await smpp.close();
+	});
+
+	test('refuses a deliver_sm sent to a peer that bound as a transmitter', async () => {
+		const smpp = await startServer();
+		const bound = once<Session>(resolve => { smpp.on('session', resolve); });
+		const { session } = await connect(smpp, { bindType: 'transmitter' });
+
+		assert.ok(session);
+
+		const peer = await bound;
+		const sent = await peer.send({
+			cmdName: 'deliver_sm',
+			params: { destination_addr: '46709771337', short_message: 'nope', source_addr: '46701113311' },
+		});
+
+		assert.ok(sent.pduObj);
+		assert.equal(sent.pduObj.cmdStatus, 'ESME_RINVBNDSTS');
+
+		session.close();
+		await smpp.close();
+	});
+
+	test('refuses sendDlr() to a transmitter-bound peer before it reaches the wire', async () => {
+		const smpp = await startServer();
+		const incoming = once<Sms>(resolve => {
+			smpp.on('session', peer => peer.on('sms', resolve));
+		});
+		const { session } = await connect(smpp, { bindType: 'transmitter' });
+
+		assert.ok(session);
+
+		const [sms] = await Promise.all([
+			incoming,
+			session.sendSms({ dlr: true, from: '46701113311', message: 'one way', to: '46709771337' }),
+		]);
+
+		await sms.sendResp();
+
+		const report = await sms.sendDlr();
+
+		assert.ok(report.err instanceof Error);
+		assert.match(report.err.message, /transmitter-bound/);
+
+		session.close();
+		await smpp.close();
+	});
+});
+
 describe('sending', () => {
 	test('delivers a simple SMS with the sender TON derived from the address', async () => {
 		const smpp = await startServer();
@@ -546,6 +633,40 @@ describe('sending', () => {
 		session.close();
 		await smpp.close();
 	});
+
+	test('puts the address TON and NPI the caller chose on the wire', async () => {
+		const smpp = await startServer();
+		const incoming = once<Sms>(resolve => {
+			smpp.on('session', peer => peer.on('sms', resolve));
+		});
+		const { session } = await connect(smpp);
+
+		assert.ok(session);
+
+		const [sms] = await Promise.all([
+			incoming,
+			session.sendSms({
+				destinationAddrNpi: consts.NPI.ISDN,
+				destinationAddrTon: consts.TON.NATIONAL,
+				from: '46701113311',
+				message: 'addressed by hand',
+				sourceAddrNpi: consts.NPI.PRIVATE,
+				sourceAddrTon: consts.TON.ABBREVIATED,
+				to: '46709771337',
+			}),
+		]);
+
+		const params = sms.pduObjs[0]?.params;
+
+		assert.ok(params);
+		assert.equal(params.dest_addr_npi, consts.NPI.ISDN);
+		assert.equal(params.dest_addr_ton, consts.TON.NATIONAL);
+		assert.equal(params.source_addr_npi, consts.NPI.PRIVATE);
+		assert.equal(params.source_addr_ton, consts.TON.ABBREVIATED);
+
+		session.close();
+		await smpp.close();
+	});
 });
 
 describe('receiving', () => {

todo.md

@@ -5,7 +5,7 @@ rules there constrain every item below.
 
 ## Status
 
-The rewrite is **feature complete and green**: 210 tests, lint and typecheck clean, verified on Node
+The rewrite is **feature complete and green**: 223 tests, lint and typecheck clean, verified on Node
 18, 20, 22 and 24. What is left is release work and a few things worth adding before or after 1.0.0.
 
 ```bash
@@ -54,12 +54,50 @@ Rules the API follows:
 | Stream framing | `test/pdu-framer.test.ts` |
 | Delivery receipt parsing, TLV and text | `test/dlr.test.ts` |
 | Session, client, server: bind, auth, send, reassembly, DLRs, timeouts, abort, send window | `test/session.test.ts` |
-| Merged multipart DLRs, reconnect, reassembly bounds, per-send abort | `test/session-extras.test.ts` |
+| Merged multipart DLRs, reconnect, reassembly bounds, per-send abort, the segment cap | `test/session-extras.test.ts` |
+| Every runnable README example | `test/readme.test.ts` |
 | Cross-checked against node-smpp both ways and over a live session | `test/interop.test.ts` |
 | CI on Node 18/20/22/24, Renovate, tag-triggered publish | `.github/workflows/` |
 
 Every defect listed in the AGENTS.md table has a regression test naming the behaviour.
 
+## The GitHub backlog, once this branch is `master`
+
+Nothing below is closed while `master` is still 0.4.0 — declining a security bump on a live default
+branch is worse than leaving it open. Work through this immediately after the merge.
+
+**Close as fixed by 1.0.0**, naming the replacement in the comment:
+
+| | Fixed by |
+| --- | --- |
+| [#4](https://github.com/larvit/larvitsmpp/issues/4) DLR errors with `message_state` missing | `dlrFromPdu()` parses the `stat:` receipt text when the TLVs are absent |
+| [#33](https://github.com/larvit/larvitsmpp/issues/33) Large inbound text arrives as raw `Buffer` segments | `IncomingRequests` reassembles a UDH-carrying `deliver_sm` into one `sms` event |
+| [#3](https://github.com/larvit/larvitsmpp/issues/3) Tests for flash messages | `test/session.test.ts` |
+| [#20](https://github.com/larvit/larvitsmpp/issues/20) Tests fail on current dependency versions | The mocha suite is gone; `node:test` on Node 18/20/22/24 |
+| [#2](https://github.com/larvit/larvitsmpp/issues/2) Tests for the README examples | `test/readme.test.ts` |
+| [#17](https://github.com/larvit/larvitsmpp/issues/17) `addr_ton`/`addr_npi` should be settable | `sendSms()` takes all four, documented and tested |
+| [#16](https://github.com/larvit/larvitsmpp/issues/16) Support all three bind types | Bound and enforced in both directions |
+| [#13](https://github.com/larvit/larvitsmpp/issues/13) Limit a long SMS to fewer segments | The `maxSegments` send option |
+| [#68](https://github.com/larvit/larvitsmpp/pull/68) `message_id` in `submit_sm_resp`, spec DLR codes | All four hold: `sendResp()` always answers a `message_id`, per segment; `stat:UNDELIV` is the 7-character code. Credit the reporter — the fork found real defects. |
+
+**Close as superseded**, all against 0.4.0 dependencies the rewrite does not have — `async`,
+`coveralls`, `eslint`, `iconv-lite`, `larvitutils`, `mocha`, `mocha-eslint`, `portfinder`, `uuid`:
+[#40](https://github.com/larvit/larvitsmpp/pull/40), [#41](https://github.com/larvit/larvitsmpp/pull/41),
+[#42](https://github.com/larvit/larvitsmpp/pull/42), [#45](https://github.com/larvit/larvitsmpp/pull/45),
+[#46](https://github.com/larvit/larvitsmpp/pull/46), [#47](https://github.com/larvit/larvitsmpp/pull/47),
+[#59](https://github.com/larvit/larvitsmpp/pull/59), [#63](https://github.com/larvit/larvitsmpp/pull/63),
+[#64](https://github.com/larvit/larvitsmpp/pull/64), [#65](https://github.com/larvit/larvitsmpp/pull/65),
+[#67](https://github.com/larvit/larvitsmpp/pull/67), [#70](https://github.com/larvit/larvitsmpp/pull/70).
+[#70](https://github.com/larvit/larvitsmpp/pull/70) is the open `uuid` advisory GitHub reports on the
+default branch; it disappears with the runtime dependencies rather than being fixed.
+
+[#60](https://github.com/larvit/larvitsmpp/issues/60) is Renovate's dashboard — leave it, it
+re-baselines itself against the new `package.json`.
+
+**Leave open:** [#8](https://github.com/larvit/larvitsmpp/issues/8), the socket's remote host and
+port on log messages. Only `server - incoming connection` carries them today; putting them on every
+session message is a change to every call site.
+
 ## Before publishing 1.0.0
 
 - [ ] Create the `@larvit/smpp` package on npm and add `NPM_TOKEN` to the repository secrets, which
@@ -71,10 +109,19 @@ Every defect listed in the AGENTS.md table has a regression test naming the beha
 
 ## Worth doing, not blocking
 
+- [ ] **An `async` event listener that rejects escapes the guard.** `Session.emit()` wraps
+      `super.emit()` in try/catch, which catches a listener that throws synchronously but not one
+      that returns a rejected promise — that surfaces as an unhandled rejection and takes the
+      process down, which hard rule 1 says must not happen. Every README example uses
+      `session.on('sms', async sms => …)`, so the shape is the one applications will write. The
+      library's own calls inside such a listener never reject, so the examples themselves are safe.
+      Fixing it means dispatching `rawListeners()` by hand in `emit()` and routing a rejection to
+      `sessionError` — a change to the hottest path, so it needs a decision before 1.0.0.
+
 - [ ] **In-flight sends across a reconnect.** They currently fail with "Session closed before a
       response arrived" and the caller retries. Re-queueing them automatically would be friendlier
       but risks duplicate delivery, so it needs a decision before it is built.
-- [ ] **`session.ts` is 459 lines.** The one seam left in it is a socket-to-PDU transport, which
+- [ ] **`session.ts` is 386 lines.** The one seam left in it is a socket-to-PDU transport, which
       would move the deliberately public `sock` field out of `Session` or turn it into a getter —
       a public-surface change, so it waits for a decision.
 - [ ] **Group the session's collaborators under `src/session/`.** Only `session.ts` imports