From 6e02263f8dc7b5a53bdbadd4134b7ab215717a90 Mon Sep 17 00:00:00 2001
From: Jan Romann <jan.romann@uni-bremen.de>
Date: Mon, 24 Jul 2023 17:26:42 +0200
Subject: [PATCH] fixup! refactor(coap-server): refactor request handling

---
 packages/binding-coap/src/coap-server.ts | 44 ++++++++++++++++--------
 1 file changed, 30 insertions(+), 14 deletions(-)

diff --git a/packages/binding-coap/src/coap-server.ts b/packages/binding-coap/src/coap-server.ts
index 181fa6070..c6980c33f 100644
--- a/packages/binding-coap/src/coap-server.ts
+++ b/packages/binding-coap/src/coap-server.ts
@@ -28,7 +28,7 @@ import Servient, {
     createLoggers,
 } from "@node-wot/core";
 import { Socket } from "dgram";
-import { Server, createServer, registerFormat, IncomingMessage, OutgoingMessage } from "coap";
+import { Server, createServer, registerFormat, IncomingMessage, OutgoingMessage, OptionValue } from "coap";
 import slugify from "slugify";
 import { Readable } from "stream";
 import { MdnsIntroducer } from "./mdns-introducer";
@@ -339,26 +339,42 @@ export default class CoapServer implements ProtocolServer {
             return;
         }
 
-        const accept = req.headers.Accept;
+        const { contentType, isSupported } = this.processAcceptValue(req);
+
+        if (!isSupported) {
+            this.sendResponse(res, "4.06", `Content-Format ${contentType} is not supported by this resource.`);
+            return;
+        }
 
-        const contentSerdes = ContentSerdes.get();
+        const content = ContentSerdes.get().valueToContent(thing.getThingDescription(), undefined, contentType);
+        const payload = await ProtocolHelpers.readStreamFully(content.body);
 
-        const isUnsupportedAcceptValue = typeof accept === "string" && !contentSerdes.isSupported(accept);
+        debug(`Sending CoAP response for TD with Content-Format ${contentType}.`);
+        this.sendContentResponse(res, payload, contentType);
+    }
 
-        if (isUnsupportedAcceptValue) {
-            debug(`Request contained an accept option with value ${accept} which is not supported.`);
-            this.sendResponse(res, "4.06", `Content-Format ${accept} is not supported by this resource.`);
-            return;
+    private processAcceptValue(req: IncomingMessage) {
+        const accept = req.headers.Accept;
+
+        if (typeof accept !== "string") {
+            debug(`Request contained no Accept option.`);
+            return {
+                contentType: ContentSerdes.TD,
+                isSupported: true,
+            };
         }
 
-        debug(`Received an available or no Content-Format (${accept}) in Accept option.`);
-        const contentFormat = (accept as string) ?? ContentSerdes.TD;
+        const isSupported = ContentSerdes.get().isSupported(accept);
 
-        const content = contentSerdes.valueToContent(thing.getThingDescription(), undefined, contentFormat);
-        const payload = await ProtocolHelpers.readStreamFully(content.body);
+        if (!isSupported) {
+            debug(`Request contained an accept option with value ${accept} which is not supported.`);
+        }
 
-        debug(`Sending CoAP response for TD with Content-Format ${contentFormat}.`);
-        this.sendContentResponse(res, payload, contentFormat);
+        debug(`Received an available Content-Format ${accept} in Accept option.`);
+        return {
+            contentType: accept,
+            isSupported,
+        };
     }
 
     private async handleRequest(req: IncomingMessage, res: OutgoingMessage) {