CHANGELOG.md

@@ -32,6 +32,8 @@
   a caller that reads only `smsIds` meets a failure it has not met before. A whole number in an
   address or an id still spells its digits, so `message_id: 123` is unchanged. The integer fields
   name a refused `NaN` too, where the refusal used to read `null`.
+- An inbound `alert_notification` or `outbind` is logged and left unanswered, as SMPP 3.4 gives
+  neither a response. Each used to raise a `sessionError`.
 
 ## 0.5.0
 

src/incoming-requests.ts

@@ -16,6 +16,7 @@ import { createSms } from './sms.ts';
 import { dlrFromPdu } from './dlr.ts';
 import { paramText } from './defs/types.ts';
 import { respIdParams, segmentId } from './sms-id.ts';
+import { respNameFor } from './defs/commands.ts';
 
 /** SMPP 3.4 lists ESME_RMSGQFUL under submit_sm_resp only; 4.6.2's retryable code is another. */
 export function refusedSegmentStatus(
@@ -171,6 +172,12 @@ export class IncomingRequests {
 			return;
 		}
 
+		if (!respNameFor(pduObj.cmdName)) {
+			this.log.info('session - ignoring a command that takes no response', { cmdName: pduObj.cmdName });
+
+			return;
+		}
+
 		this.log.info('session - no handler for command', { cmdName: pduObj.cmdName });
 		await this.session.sendReturn(pduObj, 'ESME_RINVCMDID');
 	}

test/session.test.ts

@@ -1792,6 +1792,26 @@ describe('a PDU the codec cannot read', () => {
 		assert.ok((await raceWithin(2000, failed)) instanceof Error, 'one sessionError per refused PDU');
 	});
 
+	test('answers neither alert_notification nor outbind, which have no response', async t => {
+		const { peer, session } = await bound(t);
+		let failures = 0;
+
+		session.on('sessionError', () => { failures++; });
+		peer.writeRaw(pduBytes({
+			cmdName: 'alert_notification',
+			params: { esme_addr: '46701234567', source_addr: '46709876543' },
+			seqNr: 3,
+		}));
+		peer.writeRaw(pduBytes({ cmdName: 'outbind', params: { password: 'pw', system_id: 'smsc' }, seqNr: 4 }));
+		peer.writeRaw(pduBytes({ cmdName: 'enquire_link', seqNr: 5 }));
+
+		const answered = await answerTo(peer);
+
+		assert.equal(answered.cmdName, 'enquire_link_resp');
+		assert.equal(answered.seqNr, 5);
+		assert.equal(failures, 0);
+	});
+
 	test('answers a deliver_sm with a truncated TLV stream with ESME_RINVTLVSTREAM', async t => {
 		const { peer, session } = await bound(t);
 		let reports = 0;

todo.md

@@ -200,12 +200,6 @@ and is also what the panel ranked hardest — two methods, one answer.
       caller never wrote." A goal is the maintainer's, so nothing edits README until that is
       answered. From the prose pass of #18.
 
-- [ ] **Answer `alert_notification` and `outbind` by not answering them.** Both are response-less in
-      SMPP 3.4, both fall through `route()`'s default into `unhandled()`, which calls
-      `sendReturn(pduObj, 'ESME_RINVCMDID')`; `pduReturn()` then finds no response command, and the
-      failure reaches the application as `sessionError` on every occurrence. `alert_notification`
-      appears nowhere in `src/` but `defs/commands.ts`. One case arm each: log and return.
-
 - [ ] **Range-check `maxOctets` with its five siblings.** `limitsOf()` in `session-options.ts`
       covers `idleTimeout`, `maxOutstanding`, `maxReassembly`, `reassemblyTimeout`, `responseTimeout`
       and `shutdownTimeout`; `maxOctets` is documented, consumed by `Reassembler`, and absent from