fix: handling preflight requests (#66)

* fix: handling preflight requests

* rename handler

packages/edge-gateway-link/src/cors.js

@@ -33,3 +33,17 @@ export function addCorsHeaders (request, response) {
   response.headers.set('Access-Control-Expose-Headers', 'Link')
   return response
 }
+
+/**
+ * Handle OPTIONS requests in the proxy itself by returning a 204 No Content response with CORS headers.
+ *
+ * @param {Request} request
+ * @returns {Response}
+ */
+export function corsPreflightRequest (request) {
+  const headers = new Headers()
+  headers.set('Access-Control-Allow-Origin', request.headers.get('origin') || '*')
+  headers.set('Access-Control-Allow-Methods', 'GET, HEAD, POST, OPTIONS')
+  headers.set('Access-Control-Allow-Headers', 'Content-Type, Authorization')
+  return new Response(null, { headers, status: 204 })
+}

packages/edge-gateway-link/src/index.js

@@ -7,7 +7,7 @@ import { ipnsGet } from './ipns.js'
 import { versionGet } from './version.js'
 import { gatewayGet } from './gateway.js'
 
-import { addCorsHeaders, withCorsHeaders } from './cors.js'
+import { addCorsHeaders, corsPreflightRequest, withCorsHeaders } from './cors.js'
 import { errorHandler } from './error-handler.js'
 import { envAll } from './env.js'
 
@@ -18,6 +18,7 @@ const router = Router()
 
 router
   .all('*', envAll)
+  .options('*', corsPreflightRequest)
   .post('*', withCorsHeaders(proxyPostRequest))
   .get('/version', withCorsHeaders(versionGet))
   .get('/ipfs/:cid', withCorsHeaders(ipfsGet))
@@ -45,7 +46,7 @@ function serverError (error, request, env) {
  * @param {import('./env').Env} env
  * @returns {Promise<Response>}
  */
-async function proxyPostRequest(request, env) {
+async function proxyPostRequest (request, env) {
   const originRequest = new Request(request)
   const url = new URL(request.url)
   const targetUrl = new URL(url.pathname, env.UCANTO_SERVER_URL)

packages/edge-gateway-link/test/gateway.spec.js

@@ -99,3 +99,10 @@ test('Proxies POST requests to the UCANTO Server', async t => {
   t.is(res.headers.get('X-Proxied-By'), 'TestUcantoServer')
   t.true(res.ok)
 })
+
+test('Handles OPTIONS requests', async t => {
+  const res = await t.context.mf.dispatchFetch('http://localhost:8787', {
+    method: 'OPTIONS'
+  })
+  t.is(res.status, 204)
+})

packages/edge-gateway-link/test/scripts/gateway.js

@@ -16,8 +16,7 @@ export default {
         request.url.replace('localhost:8787', IPFS_GATEWAY_REDIRECT_HOSTNAME),
         307
       )
-    }
-    else if (subdomainCid) {
+    } else if (subdomainCid) {
       const headers = new Headers({
         etag: subdomainCid
       })