fix: cors server errors

server/capi.dev/delegator.ts

@@ -1,8 +1,8 @@
 import { serve } from "../../deps/std/http.ts"
 import { TimedMemo } from "../../util/memo.ts"
-import { f, handleErrors } from "../mod.ts"
+import { f, handleCors, handleErrors } from "../mod.ts"
 
-serve(handleErrors(handler))
+serve(handleCors(handleErrors(handler)))
 
 const ttl = 60_000
 const shaAbbrevLength = 8

server/handler.ts

@@ -1,10 +1,10 @@
-import { Handler } from "../deps/std/http.ts"
+import { Handler, Status } from "../deps/std/http.ts"
 import { Env } from "./Env.ts"
 import * as f from "./factories.ts"
 import { parsePathInfo } from "./PathInfo.ts"
 
 export function handler(env: Env): Handler {
-  return handleErrors(async (request) => {
+  return handleCors(handleErrors(async (request) => {
     const url = new URL(request.url)
     const { pathname } = url
     if (pathname === "/") return new Response("capi dev server active")
@@ -34,19 +34,53 @@ export function handler(env: Env): Handler {
       } catch (_e) {}
     }
     return f.notFound()
-  })
+  }))
 }
 
 const staticDirs = ["../", "./static/"].map((p) => import.meta.resolve(p))
 
-export function handleErrors(handler: (request: Request) => Promise<Response>) {
-  return async (request: Request) => {
+export function handleErrors(handler: Handler): Handler {
+  return async (request, connInfo) => {
     try {
-      return await handler(request)
+      return await handler(request, connInfo)
     } catch (e) {
       if (e instanceof Response) return e.clone()
       console.error(e)
       return f.serverError(Deno.inspect(e))
     }
   }
 }
+
+export function handleCors(handler: Handler): Handler {
+  return async (request, connInfo) => {
+    const newHeaders = new Headers()
+    newHeaders.set("Access-Control-Allow-Origin", "*")
+    newHeaders.set("Access-Control-Allow-Headers", "*")
+    newHeaders.set("Access-Control-Allow-Methods", "*")
+    newHeaders.set("Access-Control-Allow-Credentials", "true")
+
+    if (request.method === "OPTIONS") {
+      return new Response(null, {
+        headers: newHeaders,
+        status: Status.NoContent,
+      })
+    }
+
+    const res = await handler(request, connInfo)
+
+    // Deno.upgradeWebSocket response objects cannot be modified
+    if (res.headers.get("upgrade") !== "websocket") {
+      for (const [k, v] of res.headers) {
+        newHeaders.append(k, v)
+      }
+
+      return new Response(res.body, {
+        headers: newHeaders,
+        status: res.status,
+        statusText: res.statusText,
+      })
+    }
+
+    return res
+  }
+}