Allow registering multiple ContentCodecs per media type with optional scheme support

packages/binding-coap/README.md

@@ -52,6 +52,75 @@ servient
     });
 ```
 
+## Using PSK with CoAPs (DTLS)
+
+The CoAP binding also supports secure communication over `coaps://` using DTLS with Pre-Shared Keys (PSK).
+
+To use PSK security, define a `psk` security scheme in the Thing Description and provide the credentials when consuming the Thing.
+
+### Thing Description Example (PSK)
+
+```json
+{
+    "title": "SecureThing",
+    "securityDefinitions": {
+        "psk_sc": {
+            "scheme": "psk"
+        }
+    },
+    "security": ["psk_sc"],
+    "properties": {
+        "count": {
+            "type": "integer",
+            "forms": [
+                {
+                    "href": "coaps://localhost:5684/count"
+                }
+            ]
+        }
+    }
+}
+```
+
+### Client Example with PSK
+
+```js
+const { Servient } = require("@node-wot/core");
+const { CoapClientFactory } = require("@node-wot/binding-coap");
+
+const servient = new Servient();
+servient.addClientFactory(new CoapClientFactory());
+
+servient
+    .start()
+    .then(async (WoT) => {
+        try {
+            const td = await WoT.requestThingDescription("coaps://localhost:5684/secureThing");
+            const thing = await WoT.consume(td);
+
+            // configure PSK security
+            thing.setSecurity(td.securityDefinitions, {
+                identity: "Client_identity",
+                psk: "secretPSK",
+            });
+
+            const value = await thing.readProperty("count");
+            console.log("count value is:", await value.value());
+        } catch (err) {
+            console.error("Script error:", err);
+        }
+    })
+    .catch((err) => {
+        console.error("Start error:", err);
+    });
+```
+
+### Notes
+
+-   The `identity` must match the server configuration.
+-   The `psk` must match the server's configured secret.
+-   Currently, only the `psk` security scheme is supported for `coaps://` in this binding.
+
 ### Server Example
 
 The server example produces a thing that allows for setting a property `count`. The thing is reachable through CoAP.

packages/binding-coap/eslint.config.mjs

@@ -0,0 +1,10 @@
+import rootConfig from "../../eslint.config.mjs";
+
+export default [
+    ...rootConfig,
+    {
+        rules: {
+            "@typescript-eslint/no-unnecessary-condition": "warn",
+        },
+    },
+];

packages/binding-coap/src/coap-client.ts

@@ -65,7 +65,9 @@ export default class CoapClient implements ProtocolClient {
                 debug(`CoapClient received Content-Format: ${res.headers["Content-Format"]}`);
 
                 // FIXME does not work with blockwise because of node-coap
-                const contentType = (res.headers["Content-Format"] as string) ?? form.contentType;
+                const rawContentType = res.headers["Content-Format"];
+                const contentType =
+                    typeof rawContentType === "string" ? rawContentType : (form.contentType ?? ContentSerdes.DEFAULT);
 
                 resolve(new Content(contentType, Readable.from(res.payload)));
             });
@@ -109,8 +111,11 @@ export default class CoapClient implements ProtocolClient {
                 debug(`CoapClient received ${res.code} from ${form.href}`);
                 debug(`CoapClient received Content-Format: ${res.headers["Content-Format"]}`);
                 debug(`CoapClient received headers: ${JSON.stringify(res.headers)}`);
-                const contentType = res.headers["Content-Format"] as string;
-                resolve(new Content(contentType ?? "", Readable.from(res.payload)));
+
+                const rawContentType = res.headers["Content-Format"];
+                const contentType = typeof rawContentType === "string" ? rawContentType : ContentSerdes.DEFAULT;
+
+                resolve(new Content(contentType, Readable.from(res.payload)));
             });
             req.on("error", (err: Error) => reject(err));
             (async () => {
@@ -156,10 +161,12 @@ export default class CoapClient implements ProtocolClient {
                 debug(`CoapClient received Content-Format: ${res.headers["Content-Format"]}`);
 
                 // FIXME does not work with blockwise because of node-coap
-                const contentType = res.headers["Content-Format"] ?? form.contentType ?? ContentSerdes.DEFAULT;
+                const rawContentType = res.headers["Content-Format"];
+                const contentType =
+                    typeof rawContentType === "string" ? rawContentType : (form.contentType ?? ContentSerdes.DEFAULT);
 
                 res.on("data", (data: Buffer) => {
-                    next(new Content(`${contentType}`, Readable.from(res.payload)));
+                    next(new Content(contentType, Readable.from(res.payload)));
                 });
 
                 resolve(
@@ -190,7 +197,9 @@ export default class CoapClient implements ProtocolClient {
         req.setOption("Accept", "application/td+json");
         return new Promise<Content>((resolve, reject) => {
             req.on("response", (res: IncomingMessage) => {
-                const contentType = (res.headers["Content-Format"] as string) ?? "application/td+json";
+                const rawContentType = res.headers["Content-Format"];
+                const contentType = typeof rawContentType === "string" ? rawContentType : "application/td+json";
+
                 resolve(new Content(contentType, Readable.from(res.payload)));
             });
             req.on("error", (err: Error) => reject(err));

packages/binding-coap/src/coap-server.ts

@@ -41,7 +41,10 @@ const { debug, warn, info, error } = createLoggers("binding-coap", "coap-server"
 
 type CoreLinkFormatParameters = Map<string, string[] | number[]>;
 
-type AffordanceElement = PropertyElement | ActionElement | EventElement;
+type AffordanceElement =
+    Omit<PropertyElement, "forms"> |
+    Omit<ActionElement, "forms"> |
+    Omit<EventElement, "forms">;
 
 // TODO: Move to core?
 type AugmentedInteractionOptions = WoT.InteractionOptions & { formIndex: number };
@@ -145,11 +148,6 @@ export default class CoapServer implements ProtocolServer {
         const port = this.getPort();
         const urlPath = this.createThingUrlPath(thing);
 
-        if (port === -1) {
-            warn("CoapServer is assigned an invalid port, aborting expose process.");
-            return;
-        }
-
         this.fillInBindingData(thing, port, urlPath);
 
         debug(`CoapServer on port ${port} exposes '${thing.title}' as unique '/${urlPath}'`);
@@ -236,12 +234,8 @@ export default class CoapServer implements ProtocolServer {
     }
 
     private addFormToAffordance(form: Form, affordance: AffordanceElement): void {
-        const affordanceForms = affordance.forms;
-        if (affordanceForms == null) {
-            affordance.forms = [form];
-        } else {
-            affordanceForms.push(form);
-        }
+        const withForms = affordance as AffordanceElement & { forms?: Form[] };
+        (withForms.forms ??= []).push(form);
     }
 
     private fillInPropertyBindingData(thing: ExposedThing, base: string, offeredMediaType: string) {
@@ -354,9 +348,8 @@ export default class CoapServer implements ProtocolServer {
 
     public async destroy(thingId: string): Promise<boolean> {
         debug(`CoapServer on port ${this.getPort()} destroying thingId '${thingId}'`);
-        for (const name of this.things.keys()) {
-            const exposedThing = this.things.get(name);
-            if (exposedThing?.id === thingId) {
+        for (const [name, exposedThing] of this.things.entries()) {
+            if (exposedThing.id === thingId) {
                 this.things.delete(name);
                 this.coreResources.delete(name);
                 this.mdnsIntroducer?.delete(name);
@@ -374,7 +367,7 @@ export default class CoapServer implements ProtocolServer {
         return Array.from(this.coreResources.values())
             .map((resource) => {
                 const formattedPath = `</${resource.urlPath}>`;
-                const parameters = Array.from(resource.parameters?.entries() ?? []);
+                const parameters = resource.parameters ? Array.from(resource.parameters.entries()) : [];
 
                 const parameterValues = parameters.map((parameter) => {
                     const key = parameter[0];
@@ -499,20 +492,24 @@ export default class CoapServer implements ProtocolServer {
         const { thingKey, affordanceType, affordanceKey } = this.parseUriSegments(requestUri);
         const thing = this.things.get(thingKey);
 
-        if (thing == null) {
+        if (thing === undefined) {
             this.sendNotFoundResponse(res);
             return;
         }
 
         // TODO: Remove support for trailing slashes (or rather: trailing empty URI path segments)
-        if (affordanceType == null || affordanceType === "") {
+        if (!affordanceType) {
             await this.handleTdRequest(req, res, thing);
             return;
         }
 
         switch (affordanceType) {
             case this.PROPERTY_DIR:
-                this.handlePropertyRequest(thing, affordanceKey, req, res, contentType);
+                if (!affordanceKey) {
+                    this.handlePropertiesRequest(req, contentType, thing, res);
+                } else {
+                    this.handlePropertyRequest(thing, affordanceKey, req, res, contentType);
+                }
                 break;
             case this.ACTION_DIR:
                 this.handleActionRequest(thing, affordanceKey, req, res, contentType);
@@ -554,11 +551,6 @@ export default class CoapServer implements ProtocolServer {
     ) {
         const property = thing.properties[affordanceKey];
 
-        if (property == null) {
-            this.handlePropertiesRequest(req, contentType, thing, res);
-            return;
-        }
-
         switch (req.method) {
             case "GET":
                 if (req.headers.Observe == null) {
@@ -588,7 +580,7 @@ export default class CoapServer implements ProtocolServer {
     ) {
         const forms = thing.forms;
 
-        if (forms == null) {
+        if (!forms || forms.length === 0) {
             this.sendNotFoundResponse(res);
             return;
         }
@@ -618,26 +610,33 @@ export default class CoapServer implements ProtocolServer {
                 contentType,
                 thing.uriVariables
             );
-            const readablePropertyKeys = this.getReadableProperties(thing).map(([key, _]) => key);
+
+            const readablePropertyKeys = this.getReadableProperties(thing).map(([key]) => key);
+
             const contentMap = await thing.handleReadMultipleProperties(readablePropertyKeys, interactionOptions);
 
             const recordResponse: Record<string, DataSchemaValue> = {};
             for (const [key, content] of contentMap.entries()) {
-                const value = ContentSerdes.get().contentToValue(
-                    { type: ContentSerdes.DEFAULT, body: await content.toBuffer() },
-                    {}
-                );
-
-                if (value == null) {
-                    // TODO: How should this case be handled?
+                try {
+                    if (
+                        content.type !== ContentSerdes.DEFAULT &&
+                        content.type !== "application/json"
+                    ) {
+                        continue;
+                    }
+                    const buffer = await content.toBuffer();
+                    const parsed = JSON.parse(buffer.toString());
+
+                    recordResponse[key] = parsed;
+                } catch {
+                    // Ignore non-JSON properties
                     continue;
                 }
-
-                recordResponse[key] = value;
             }
 
-            const content = ContentSerdes.get().valueToContent(recordResponse, undefined, contentType);
-            this.streamContentResponse(res, content);
+            const responseContent = ContentSerdes.get().valueToContent(recordResponse,undefined,contentType);
+
+            this.streamContentResponse(res, responseContent);
         } catch (err) {
             const errorMessage = `${err}`;
             error(`CoapServer on port ${this.getPort()} got internal error on read '${req.url}': ${errorMessage}`);
@@ -775,11 +774,6 @@ export default class CoapServer implements ProtocolServer {
     ) {
         const action = thing.actions[affordanceKey];
 
-        if (action == null) {
-            this.sendNotFoundResponse(res);
-            return;
-        }
-
         if (req.method !== "POST") {
             this.sendMethodNotAllowedResponse(res);
             return;
@@ -837,19 +831,14 @@ export default class CoapServer implements ProtocolServer {
     ) {
         const event = thing.events[affordanceKey];
 
-        if (event == null) {
-            this.sendNotFoundResponse(res);
-            return;
-        }
-
         if (req.method !== "GET") {
             this.sendMethodNotAllowedResponse(res);
             return;
         }
 
-        const observe = req.headers.Observe as number;
+        const observe = req.headers.Observe as number | undefined;
 
-        if (observe == null) {
+        if (observe === undefined) {
             debug(
                 `CoapServer on port ${this.getPort()} rejects '${affordanceKey}' event subscription from ${Helpers.toUriLiteral(
                     req.rsinfo.address
@@ -923,17 +912,18 @@ export default class CoapServer implements ProtocolServer {
     }
 
     private getContentTypeFromRequest(req: IncomingMessage): string {
-        const contentType = req.headers["Content-Format"] as string;
+        const contentType = req.headers["Content-Format"] as string | undefined;
 
-        if (contentType == null) {
+        if (contentType === undefined) {
             warn(
                 `CoapServer on port ${this.getPort()} received no Content-Format from ${Helpers.toUriLiteral(
                     req.rsinfo.address
                 )}:${req.rsinfo.port}`
             );
+            return ContentSerdes.DEFAULT;
         }
 
-        return contentType ?? ContentSerdes.DEFAULT;
+        return contentType;
     }
 
     private checkContentTypeSupportForInput(method: string, contentType: string): boolean {
@@ -974,7 +964,7 @@ export default class CoapServer implements ProtocolServer {
     }
 
     // TODO: The name of this method might not be ideal yet.
-    private streamContentResponse(res: OutgoingMessage, content: Content, options?: { end?: boolean | undefined }) {
+    private streamContentResponse(res: OutgoingMessage, content: Content, options?: { end?: boolean }) {
         res.setOption("Content-Format", content.type);
         res.code = "2.05";
         content.body.pipe(res, options);

packages/binding-coap/src/coaps-client.ts

@@ -110,13 +110,13 @@ export default class CoapsClient implements ProtocolClient {
     ): Promise<Subscription> {
         return new Promise<Subscription>((resolve, reject) => {
             const requestUri = new URL(form.href.replace(/$coaps/, "https"));
-            if (this.authorization != null) {
+            if (this.authorization !== undefined) {
                 coaps.setSecurityParams(requestUri.hostname, this.authorization);
             }
 
             const callback = (resp: CoapResponse) => {
                 if (resp.payload != null) {
-                    next(new Content(form?.contentType ?? ContentSerdes.DEFAULT, Readable.from(resp.payload)));
+                    next(new Content(form.contentType ?? ContentSerdes.DEFAULT, Readable.from(resp.payload)));
                 }
             };
 
@@ -163,14 +163,14 @@ export default class CoapsClient implements ProtocolClient {
     }
 
     public setSecurity(metadata: Array<SecurityScheme>, credentials?: pskSecurityParameters): boolean {
-        if (metadata === undefined || !Array.isArray(metadata) || metadata.length === 0) {
+        if (!Array.isArray(metadata) || metadata.length === 0) {
             warn(`CoapsClient received empty security metadata`);
             return false;
         }
 
         const security: SecurityScheme = metadata[0];
 
-        if (security.scheme === "psk" && credentials != null) {
+        if (security.scheme === "psk" && credentials !== undefined) {
             this.authorization = { psk: {} };
             this.authorization.psk[credentials.identity] = credentials.psk;
         } else if (security.scheme === "apikey") {
@@ -224,7 +224,7 @@ export default class CoapsClient implements ProtocolClient {
     ): Promise<CoapResponse> {
         // url only works with http*
         const requestUri = new URL(form.href.replace(/$coaps/, "https"));
-        if (this.authorization != null) {
+        if (this.authorization !== undefined) {
             coaps.setSecurityParams(requestUri.hostname, this.authorization);
         }