From 759ae56bdc1d992a87070f6476d2d4c5de1f2ced Mon Sep 17 00:00:00 2001
From: Joel Wetzell <jwetzell@yahoo.com>
Date: Sat, 7 Dec 2024 11:41:03 -0600
Subject: [PATCH] add sdt NAK data decoding

---
 README.md                   |  2 +-
 packages/acn/src/models.ts  | 20 +++++++++++++++++++-
 packages/acn/src/pdu/sdt.ts | 26 +++++++++++++++++++++++---
 3 files changed, 43 insertions(+), 5 deletions(-)

diff --git a/README.md b/README.md
index fa46500..1293b2d 100644
--- a/README.md
+++ b/README.md
@@ -9,7 +9,7 @@ not sure how far I will take this but messing around with E1.17 ACN protocol
     - [x] JOIN_REFUSE
     - [x] JOIN_ACCEPT
     - [x] LEAVING
-    - [ ] NAK
+    - [x] NAK
     - [x] REL_WRAP
     - [x] UNREL_WRAP
     - [x] GET_SESSIONS
diff --git a/packages/acn/src/models.ts b/packages/acn/src/models.ts
index addb466..e9a49e3 100644
--- a/packages/acn/src/models.ts
+++ b/packages/acn/src/models.ts
@@ -111,6 +111,15 @@ export type SDTAckData = {
   reliableSequenceNumber: number;
 };
 
+export type SDTNakData = {
+  leaderComponenetID: string;
+  channelNumber: number;
+  memberID: number;
+  reliableSequenceNumber: number;
+  firstMissedSequence: number;
+  lastMissedSequence: number;
+};
+
 export type SDTGetSessionsData = {
   componentID: string;
 };
@@ -118,7 +127,16 @@ export type SDTGetSessionsData = {
 export type SessionDataTransportPDU = {
   vector: SessionDataTransportVectors;
   // TODO(jwetzell): cleanup these types
-  data: SDTJoinData | SDTJoinAcceptData | SDTJoinRefuseData | SDTWrapperData | SDTAckData | SDTLeavingData | SDTGetSessionsData | Uint8Array;
+  data:
+    | SDTJoinData
+    | SDTJoinAcceptData
+    | SDTJoinRefuseData
+    | SDTWrapperData
+    | SDTAckData
+    | SDTLeavingData
+    | SDTGetSessionsData
+    | SDTNakData
+    | Uint8Array;
 };
 
 export type SDTClientBlock = {
diff --git a/packages/acn/src/pdu/sdt.ts b/packages/acn/src/pdu/sdt.ts
index 02e2a34..a5e593d 100644
--- a/packages/acn/src/pdu/sdt.ts
+++ b/packages/acn/src/pdu/sdt.ts
@@ -6,6 +6,7 @@ import {
   SDTJoinData,
   SDTJoinRefuseData,
   SDTLeavingData,
+  SDTNakData,
   SDTWrapperData,
   SessionDataTransportPDU,
   SessionDataTransportVectors,
@@ -125,7 +126,16 @@ function decodeClientBlock(bytes: Uint8Array) {
 function decodeData(
   vector: SessionDataTransportVectors,
   bytes: Uint8Array
-): SDTJoinData | SDTJoinAcceptData | SDTJoinRefuseData | SDTWrapperData | SDTAckData | SDTLeavingData | SDTGetSessionsData | Uint8Array {
+):
+  | SDTJoinData
+  | SDTJoinAcceptData
+  | SDTJoinRefuseData
+  | SDTWrapperData
+  | SDTAckData
+  | SDTLeavingData
+  | SDTGetSessionsData
+  | SDTNakData
+  | Uint8Array {
   const view = new DataView(bytes.buffer, bytes.byteOffset, bytes.byteLength);
   switch (vector) {
     case SessionDataTransportVectors.JOIN: {
@@ -212,8 +222,18 @@ function decodeData(
     }
     case SessionDataTransportVectors.GET_SESSIONS: {
       return {
-        componentID: toHex(bytes.subarray(0, 16))
-      }
+        componentID: toHex(bytes.subarray(0, 16)),
+      };
+    }
+    case SessionDataTransportVectors.NAK: {
+      return {
+        leaderComponentID: toHex(bytes.subarray(0, 16)),
+        channelNumber: view.getUint16(16),
+        memberID: view.getUint16(18),
+        reliableSequenceNumber: view.getUint32(20),
+        firstMissedSequence: view.getUint32(24),
+        lastMissedSequence: view.getUint32(28),
+      };
     }
     default:
       console.error(`unhandled SDT vector: ${vector}`);