Say what a peer did with each receipt segment, and leave no drop unlogged

src/held-messages.ts

@@ -21,6 +21,7 @@ export class HeldMessages {
 	private readonly held: ExpiringGroups<PduObject[]>;
 	private readonly idleWaiters = new IdleWaiters();
 	private readonly log: SmppLog;
+	private readonly max: number;
 
 	constructor(options: HeldMessagesOptions) {
 		this.held = new ExpiringGroups({
@@ -29,6 +30,7 @@ export class HeldMessages {
 			timeout: options.timeout,
 		});
 		this.log = options.log;
+		this.max = options.max;
 	}
 
 	/** An application that answers no message at all may not grow this without end. */
@@ -37,12 +39,10 @@ export class HeldMessages {
 
 		if (key === undefined) return;
 
-		if (this.held.full) {
-			const evicted = this.held.takeOldest();
-
-			if (evicted) {
-				this.log.warn('heldMessages - dropping the message held longest', { seqNr: evicted[0] });
-			}
+		if (this.held.get(key)) {
+			this.log.warn('heldMessages - replacing a message on a re-used sequence number', { seqNr: key });
+		} else if (this.held.full) {
+			this.dropOldest();
 		}
 
 		this.held.set(key, pduObjs);
@@ -76,6 +76,16 @@ export class HeldMessages {
 		return this.idleWaiters.wait(() => this.held.size, timeout, signal);
 	}
 
+	private dropOldest(): void {
+		const oldest = this.held.takeOldest();
+
+		if (!oldest) return;
+
+		const [seqNr] = oldest;
+
+		this.log.warn('heldMessages - buffer full, dropping the oldest message', { max: this.max, seqNr });
+	}
+
 	private sweep(): void {
 		const expired = this.held.takeExpired();
 

src/idle-waiters.ts

@@ -18,7 +18,7 @@ export class IdleWaiters {
 	 * Resolves 0 once nothing is left, or with what still is when the timeout or the signal cuts the
 	 * wait short. A timeout of 0 waits forever.
 	 */
-	wait(remaining: () => number, timeout: number, signal?: AbortSignal): Promise<number> {
+	wait(remaining: () => number, timeout: number, signal: AbortSignal | undefined): Promise<number> {
 		if (remaining() === 0) return Promise.resolve(0);
 
 		if (signal?.aborted === true) return Promise.resolve(remaining());

src/send-window.ts

@@ -43,7 +43,7 @@ export class SendWindow {
 	}
 
 	/** Resolves 0 once nothing is left on the wire, or with what still is. */
-	idle(timeout: number, signal?: AbortSignal): Promise<number> {
+	idle(timeout: number, signal: AbortSignal | undefined): Promise<number> {
 		return this.idleWaiters.wait(() => this.unfinished(), timeout, signal);
 	}
 }

src/sms.ts

@@ -137,6 +137,28 @@ function receiptTlvs(smsId: string, status: MessageState): Record<string, TlvInp
 	};
 }
 
+function collectReceipt(sent: Result<{ pduObj: PduObject }>[]): SendDlrResult {
+	const pduObjs: PduObject[] = [];
+	let failure: Error | undefined;
+	let unanswered = 0;
+
+	for (const one of sent) {
+		if (one.err) {
+			if (one.err instanceof UnansweredError) unanswered++;
+
+			failure ??= one.err;
+		} else if (one.pduObj.cmdStatus === 'ESME_ROK') {
+			pduObjs.push(one.pduObj);
+		} else {
+			const refusal = one.pduObj.cmdStatus ?? String(one.pduObj.cmdStatusId);
+
+			failure ??= new Error(`deliver_sm refused by the peer: ${refusal}`);
+		}
+	}
+
+	return failure ? { err: failure, pduObjs, unanswered } : { pduObjs, unanswered };
+}
+
 async function sendDlr(
 	sms: Sms,
 	send: SmsHandlers['send'],
@@ -166,19 +188,5 @@ async function sendDlr(
 			...(sms.session.acceptsOptionalParams() ? { tlvs: receiptTlvs(smsId, status) } : {}),
 		});
 	}));
-	const pduObjs: PduObject[] = [];
-	let failure: Error | undefined;
-	let unanswered = 0;
-
-	for (const one of sent) {
-		if (!one.err) {
-			pduObjs.push(one.pduObj);
-		} else {
-			if (one.err instanceof UnansweredError) unanswered++;
-
-			failure ??= one.err;
-		}
-	}
-
-	return failure ? { err: failure, pduObjs, unanswered } : { pduObjs, unanswered };
+	return collectReceipt(sent);
 }