Refactor replace some HTTP related magic values by enums.

server/app.ts

@@ -11,6 +11,7 @@ import { config } from "./config";
 import type { CleartextPassword, PasswordHash, Username } from "./types";
 import { isString } from "./types";
 import Logger from "./logger";
+import { HttpHeader, HttpStatusCode, MimeType } from "./shared/utils/http";
 
 export const app: Express = express();
 
@@ -111,7 +112,7 @@ export function init(): void {
     router.use(compress());
 
     async function serveTemplate(
-        mimeType: string,
+        mimeType: MimeType,
         req: Request,
         res: Response
     ): Promise<void> {
@@ -120,13 +121,15 @@ export function init(): void {
             "utf8"
         );
 
-        res.writeHead(200, { "Content-Type": mimeType });
+        res.writeHead(HttpStatusCode.OK, {
+            [HttpHeader.CONTENT_TYPE]: mimeType,
+        });
         res.end(_.template(body)({ config: config.client }));
     }
 
     usePromise(async (req: Request, res: Response): Promise<void> => {
         if (jsTemplateFiles.indexOf(req.path) >= 0) {
-            await serveTemplate("application/javascript", req, res);
+            await serveTemplate(MimeType.APPLICATION_JSON, req, res);
         }
     });
 

server/resources/mailResource.ts

@@ -7,6 +7,7 @@ import { normalizeString, parseInteger } from "../shared/utils/strings";
 import { forConstraint } from "../shared/validation/validator";
 import type { Request, Response } from "express";
 import { isString, Mail, MailId } from "../types";
+import { HttpHeader } from "../shared/utils/http";
 
 const isValidId = forConstraint(CONSTRAINTS.id, false);
 
@@ -39,7 +40,7 @@ async function doGetAll(
 export function getAll(req: Request, res: Response): void {
     doGetAll(req)
         .then(({ total, mails }) => {
-            res.set("X-Total-Count", total.toString(10));
+            res.set(HttpHeader.X_TOTAL_COUNT, total.toString(10));
             return Resources.success(res, mails);
         })
         .catch((err) => Resources.error(res, err));

server/resources/monitoringResource.ts

@@ -14,6 +14,7 @@ import {
     NodeMonitoringStateResponse,
     toMonitoringResponse,
 } from "../types";
+import { HttpHeader } from "../shared/utils/http";
 
 const isValidToken = forConstraint(CONSTRAINTS.token, false);
 
@@ -33,7 +34,7 @@ async function doGetAll(
 export function getAll(req: Request, res: Response): void {
     doGetAll(req)
         .then(({ total, result }) => {
-            res.set("X-Total-Count", total.toString(10));
+            res.set(HttpHeader.X_TOTAL_COUNT, total.toString(10));
             Resources.success(res, result);
         })
         .catch((err) => Resources.error(res, err));

server/resources/nodeResource.ts

@@ -27,6 +27,7 @@ import {
     toNodeTokenResponse,
 } from "../types";
 import { filterUndefinedFromJSON } from "../shared/utils/json";
+import { HttpHeader } from "../shared/utils/http";
 
 const nodeFields = [
     "hostname",
@@ -165,7 +166,7 @@ export function getAll(req: Request, res: Response): void {
                 total: number;
                 pageNodes: DomainSpecificNodeResponse[];
             }) => {
-                res.set("X-Total-Count", result.total.toString(10));
+                res.set(HttpHeader.X_TOTAL_COUNT, result.total.toString(10));
                 return Resources.success(
                     res,
                     result.pageNodes.map(filterUndefinedFromJSON)

server/resources/taskResource.ts

@@ -14,6 +14,7 @@ import {
     TaskState,
     UnixTimestampSeconds,
 } from "../types";
+import { HttpHeader } from "../shared/utils/http";
 
 const isValidId = forConstraint(CONSTRAINTS.id, false);
 
@@ -109,7 +110,7 @@ async function doGetAll(
 export function getAll(req: Request, res: Response): void {
     doGetAll(req)
         .then(({ total, pageTasks }) => {
-            res.set("X-Total-Count", total.toString(10));
+            res.set(HttpHeader.X_TOTAL_COUNT, total.toString(10));
             Resources.success(res, pageTasks.map(toTaskResponse));
         })
         .catch((err) => Resources.error(res, err));

server/shared/types/newtypes.ts

@@ -68,6 +68,18 @@ export type Url = string & { readonly __tag: unique symbol };
  */
 export const isUrl = toIsNewtype(isString, "" as Url);
 
+/**
+ * Typesafe string representation of paths.
+ */
+export type Path = string & { readonly __tag: unique symbol };
+
+/**
+ * Type guard for {@link Path}.
+ *
+ * @param arg - Value to check.
+ */
+export const isPath = toIsNewtype(isString, "" as Url);
+
 /**
  * Fastd VPN key of a Freifunk node. This is the key used by the node to open a VPN tunnel to Freifunk gateways.
  */

server/shared/utils/http.ts

@@ -0,0 +1,84 @@
+/**
+ * Enum representing supported HTTP methods.
+ */
+export enum HttpMethod {
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/GET}.
+     */
+    GET = "GET",
+
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/POST}.
+     */
+    POST = "POST",
+
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/PUT}.
+     */
+    PUT = "PUT",
+
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods/DELETE}.
+     */
+    DELETE = "DELETE",
+}
+
+/**
+ * Enum representing supported HTTP headers.
+ */
+export enum HttpHeader {
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Headers/Content-Type}.
+     */
+    CONTENT_TYPE = "Content-Type",
+
+    /**
+     * Holds the total number of entities known by the server matching the request (ignoring paging parameters).
+     */
+    X_TOTAL_COUNT = "X-Total-Count",
+}
+
+/**
+ * Enum representing supported mime-types.
+ */
+export enum MimeType {
+    /**
+     * The content is JSON.
+     */
+    APPLICATION_JSON = "application/json",
+
+    /**
+     * The content is (X)HTML.
+     */
+    TEXT_HTML = "text/html",
+}
+
+/**
+ * Enum representing supported HTTP response status codes.
+ */
+export enum HttpStatusCode {
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/200}.
+     */
+    OK = 200,
+
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/400}.
+     */
+    BAD_REQUEST = 400,
+
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/404}.
+     */
+    NOT_FOUND = 404,
+
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/409}.
+     */
+    CONFLICT = 409,
+
+    /**
+     * See {@link https://developer.mozilla.org/en-US/docs/Web/HTTP/Status/500}.
+     */
+    INTERNAL_SERVER_ERROR = 500,
+}

server/utils/errorTypes.ts

@@ -1,6 +1,9 @@
+import { HttpStatusCode } from "../shared/utils/http";
+
+// TODO: Replace this by throwing typed errors.
 export default {
-    badRequest: { code: 400 },
-    notFound: { code: 404 },
-    conflict: { code: 409 },
-    internalError: { code: 500 },
+    badRequest: { code: HttpStatusCode.BAD_REQUEST },
+    notFound: { code: HttpStatusCode.NOT_FOUND },
+    conflict: { code: HttpStatusCode.CONFLICT },
+    internalError: { code: HttpStatusCode.INTERNAL_SERVER_ERROR },
 };

server/utils/resources.ts

@@ -22,6 +22,7 @@ import {
     TypeGuard,
 } from "../types";
 import { getFieldIfExists } from "../shared/utils/objects";
+import { HttpHeader, HttpStatusCode, MimeType } from "../shared/utils/http";
 
 export type RequestData = JSONObject;
 export type RequestHandler = (request: Request, response: Response) => void;
@@ -46,30 +47,34 @@ export type FilterClause = { query: string; params: unknown[] };
 
 function respond(
     res: Response,
-    httpCode: number,
+    httpCode: HttpStatusCode,
     data: string,
-    type: "html"
+    type: MimeType.TEXT_HTML
 ): void;
 function respond(
     res: Response,
-    httpCode: number,
+    httpCode: HttpStatusCode,
     data: JSONValue,
-    type: "json"
+    type: MimeType.APPLICATION_JSON
 ): void;
 function respond(
     res: Response,
-    httpCode: number,
+    httpCode: HttpStatusCode,
     data: JSONValue,
-    type: "html" | "json"
+    type: MimeType.APPLICATION_JSON | MimeType.TEXT_HTML
 ): void {
     switch (type) {
-        case "html":
-            res.writeHead(httpCode, { "Content-Type": "text/html" });
+        case MimeType.TEXT_HTML:
+            res.writeHead(httpCode, {
+                [HttpHeader.CONTENT_TYPE]: MimeType.TEXT_HTML,
+            });
             res.end(data);
             break;
 
         default:
-            res.writeHead(httpCode, { "Content-Type": "application/json" });
+            res.writeHead(httpCode, {
+                [HttpHeader.CONTENT_TYPE]: MimeType.APPLICATION_JSON,
+            });
             res.end(JSON.stringify(data));
             break;
     }
@@ -365,18 +370,18 @@ export function filterClause<SortField>(
 }
 
 export function success(res: Response, data: JSONValue) {
-    respond(res, 200, data, "json");
+    respond(res, HttpStatusCode.OK, data, MimeType.APPLICATION_JSON);
 }
 
 export function successHtml(res: Response, html: string) {
-    respond(res, 200, html, "html");
+    respond(res, HttpStatusCode.OK, html, MimeType.APPLICATION_JSON);
 }
 
 export function error(
     res: Response,
-    err: { data: JSONValue; type: { code: number } }
+    err: { data: JSONValue; type: { code: HttpStatusCode } }
 ) {
-    respond(res, err.type.code, err.data, "json");
+    respond(res, err.type.code, err.data, MimeType.APPLICATION_JSON);
 }
 
 export function handleJSON<Response>(