CommunitySolidServer/src/server/middleware/StaticAssetHandler.ts
2021-01-21 10:35:07 +01:00

58 lines
1.9 KiB
TypeScript

import { createReadStream } from 'fs';
import * as mime from 'mime-types';
import { getLoggerFor } from '../../logging/LogUtil';
import { APPLICATION_OCTET_STREAM } from '../../util/ContentTypes';
import { pipeSafely } from '../../util/StreamUtil';
import type { HttpHandlerInput } from '../HttpHandler';
import { HttpHandler } from '../HttpHandler';
import type { HttpRequest } from '../HttpRequest';
/**
* Handler that serves static resources on specific paths.
*/
export class StaticAssetHandler extends HttpHandler {
private readonly assets: Record<string, string>;
private readonly logger = getLoggerFor(this);
/**
* Creates a handler for the provided static resources.
* @param assets - A mapping from URL paths to file paths.
*/
public constructor(assets: Record<string, string>) {
super();
this.assets = { ...assets };
}
public async canHandle({ request }: HttpHandlerInput): Promise<void> {
if (request.method !== 'GET' && request.method !== 'HEAD') {
throw new Error('Only GET and HEAD requests are supported');
}
if (!(this.getAssetUrl(request) in this.assets)) {
throw new Error(`No static resource at ${request.url}`);
}
}
public async handle({ request, response }: HttpHandlerInput): Promise<void> {
// Determine the asset to serve
const filePath = this.assets[this.getAssetUrl(request)];
this.logger.debug(`Serving ${request.url} via static asset ${filePath}`);
// Send the response headers
const contentType = mime.lookup(filePath) || APPLICATION_OCTET_STREAM;
response.writeHead(200, { 'content-type': contentType });
// For HEAD, send an empty body
if (request.method === 'HEAD') {
response.end();
// For GET, stream the asset
} else {
const asset = createReadStream(filePath, 'utf8');
pipeSafely(asset, response);
}
}
private getAssetUrl({ url }: HttpRequest): string {
return !url ? '' : url.replace(/\?.*/u, '');
}
}