110 lines
3 KiB
JavaScript
110 lines
3 KiB
JavaScript
// provided by the edge runtime:
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/* global addEventListener */
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function getUrl(url, headers) {
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const urlObj = new URL(url);
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const protocol = headers.get('x-forwarded-proto');
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if (protocol) urlObj.protocol = protocol.split(/\b/).shift();
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urlObj.host = headers.get('x-forwarded-host');
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urlObj.port = headers.get('x-forwarded-port');
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return urlObj.toString();
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}
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async function respond(handler, event, options, dependencies) {
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const { Request, Response } = dependencies;
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const { isMiddleware } = options;
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event.request.headers.set(
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'host',
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event.request.headers.get('x-forwarded-host')
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);
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let response = await handler(
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new Request(
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getUrl(event.request.url, event.request.headers),
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event.request
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),
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event
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);
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if (!response) {
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if (isMiddleware) {
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// allow empty responses to pass through
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response = new Response(null, {
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headers: {
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'x-middleware-next': '1',
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},
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});
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} else {
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throw new Error(`Edge Function did not return a response.`);
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}
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}
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return response;
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}
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function toResponseError(error, Response) {
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// we can't easily show a meaningful stack trace
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// so, stick to just the error message for now
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const msg = error.cause
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? error.message + ': ' + (error.cause.message || error.cause)
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: error.message;
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return new Response(msg, {
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status: 500,
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headers: {
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'x-vercel-failed': 'edge-wrapper',
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},
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});
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}
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async function parseRequestEvent(event) {
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const serializedRequest = await event.request.text();
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const requestDetails = JSON.parse(serializedRequest);
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return requestDetails;
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}
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// This will be invoked by logic using this template
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// eslint-disable-next-line @typescript-eslint/no-unused-vars
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function registerFetchListener(module, options, dependencies) {
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let handler;
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addEventListener('fetch', async event => {
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try {
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if (typeof module.default === 'function') {
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handler = module.default;
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} else {
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if (
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['GET', 'HEAD', 'OPTIONS', 'POST', 'PUT', 'DELETE', 'PATCH'].some(
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method => typeof module[method] === 'function'
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)
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) {
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const method = event.request.method ?? 'GET';
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handler =
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typeof module[method] === 'function'
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? module[method]
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: () => new dependencies.Response(null, { status: 405 });
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}
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}
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if (!handler) {
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const url = getUrl(event.request.url, event.request.headers);
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throw new Error(
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`No default or HTTP-named export was found at ${url}. Add one to handle requests. Learn more: https://vercel.link/creating-edge-middleware`
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);
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}
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const response = await respond(
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(req, ctx) => handler(req, { waitUntil: ctx.waitUntil.bind(ctx) }),
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event,
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options,
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dependencies
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);
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event.respondWith(response);
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} catch (error) {
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event.respondWith(toResponseError(error, dependencies.Response));
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}
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});
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}
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module.exports = {
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getUrl,
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parseRequestEvent,
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registerFetchListener,
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respond,
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toResponseError,
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};
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