chore(apps): Add proxy

1 files changed, 113 insertions, 0 deletions

diff --git a/apps/proxy/src/index.js b/apps/proxy/src/index.js
new file mode 100644
index 00000000..f2a37111
--- /dev/null
+++ b/apps/proxy/src/index.js
@@ -0,0 +1,113 @@
+const handleRequest = async (request) => {
+	try {
+		const url = new URL(request.url);
+		let query;
+		let dropHeaders = false;
+
+		if (url.search.includes('&dh')) {
+			url.search = url.search.replace('&dh', '');
+			dropHeaders = true;
+		}
+
+		if (url.search.includes('?q=')) {
+			query = url.search.split('?q=')[1];
+		} else if (url.search.includes('?d=')) {
+			query = atob(url.search.split('?d=')[1]);
+		} else if (url.search.includes('?d2=')) {
+			const fullEncodedURL = url.search.split('?d2=')[1];
+			const key = parseInt(fullEncodedURL.slice(-2));
+
+			query = atob(fullEncodedURL.slice(0, -2))
+				.split(':')
+				.map((char) => String.fromCharCode(char - key))
+				.join('');
+		} else {
+			return new Response(null, {
+				status: 400,
+				statusText: 'Bad Request',
+			});
+		}
+
+		request = new Request(query, request);
+
+		request.headers.set('Host', new URL(query).origin);
+		request.headers.set('Referrer', new URL(query));
+		request.headers.set('Origin', new URL(query));
+		request.headers.set('Access-Control-Allow-Credentials', 'true');
+		request.headers.delete('X-Content-Type-Options');
+
+		let response = await fetch(request);
+
+		response = new Response(response.body, response);
+
+		if (dropHeaders) response.headers.forEach((_, key) => response.headers.delete(key));
+
+		response.headers.set('Access-Control-Allow-Origin', 'https://due.moe');
+		response.headers.append('Vary', 'Origin');
+		response.headers.set('Cache-Control', 'max-age=300');
+
+		return response;
+	} catch {
+		return new Response(null, {
+			status: 400,
+			statusText: 'Bad Request',
+		});
+	}
+};
+
+const handleOptions = async (request) => {
+	if (
+		request.headers.get('Origin') !== null &&
+		request.headers.get('Access-Control-Request-Method') !== null &&
+		request.headers.get('Access-Control-Request-Headers') !== null
+	) {
+		return new Response(null, {
+			headers: {
+				'Access-Control-Allow-Origin': '*',
+				'Access-Control-Allow-Methods': 'GET, HEAD, POST, OPTIONS',
+				'Access-Control-Allow-Headers': '*',
+			},
+		});
+	} else {
+		return new Response(null, {
+			headers: {
+				Allow: 'GET, HEAD, POST, OPTIONS',
+			},
+		});
+	}
+};
+
+addEventListener('fetch', (event) => {
+	const request = event.request;
+
+	try {
+		switch (request.method) {
+			case 'OPTIONS':
+				event.respondWith(handleOptions(request));
+
+				break;
+
+			case 'GET':
+			case 'HEAD':
+			case 'POST':
+				event.respondWith(handleRequest(request));
+
+				break;
+
+			default:
+				event.respondWith(async () => {
+					return new Response(null, {
+						status: 405,
+						statusText: 'Method Not Allowed',
+					});
+				});
+
+				break;
+		}
+	} catch {
+		return new Response(null, {
+			status: 400,
+			statusText: 'Bad Request',
+		});
+	}
+});