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handler.js
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handler.js
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import 'SHIMS';
import fs from 'node:fs';
import path from 'node:path';
import sirv from 'sirv';
import { fileURLToPath } from 'node:url';
import { parse as polka_url_parser } from '@polka/url';
import { getRequest, setResponse } from '@sveltejs/kit/node';
import { Server } from 'SERVER';
import { manifest, prerendered } from 'MANIFEST';
import { env } from 'ENV';
/* global ENV_PREFIX */
const server = new Server(manifest);
await server.init({ env: process.env });
const origin = env('ORIGIN', undefined);
const xff_depth = parseInt(env('XFF_DEPTH', '1'));
const address_header = env('ADDRESS_HEADER', '').toLowerCase();
const protocol_header = env('PROTOCOL_HEADER', '').toLowerCase();
const host_header = env('HOST_HEADER', 'host').toLowerCase();
const body_size_limit = parseInt(env('BODY_SIZE_LIMIT', '524288'));
const dir = path.dirname(fileURLToPath(import.meta.url));
/**
* @param {string} path
* @param {boolean} client
*/
function serve(path, client = false) {
return (
fs.existsSync(path) &&
sirv(path, {
etag: true,
gzip: true,
brotli: true,
setHeaders:
client &&
((res, pathname) => {
// only apply to build directory, not e.g. version.json
if (pathname.startsWith(`/${manifest.appPath}/immutable/`) && res.statusCode === 200) {
res.setHeader('cache-control', 'public,max-age=31536000,immutable');
}
})
})
);
}
// required because the static file server ignores trailing slashes
/** @returns {import('polka').Middleware} */
function serve_prerendered() {
const handler = serve(path.join(dir, 'prerendered'));
return (req, res, next) => {
let { pathname, search, query } = polka_url_parser(req);
try {
pathname = decodeURIComponent(pathname);
} catch {
// ignore invalid URI
}
if (prerendered.has(pathname)) {
return handler(req, res, next);
}
// remove or add trailing slash as appropriate
let location = pathname.at(-1) === '/' ? pathname.slice(0, -1) : pathname + '/';
if (prerendered.has(location)) {
if (query) location += search;
res.writeHead(308, { location }).end();
} else {
next();
}
};
}
/** @type {import('polka').Middleware} */
const ssr = async (req, res) => {
/** @type {Request | undefined} */
let request;
try {
request = await getRequest({
base: origin || get_origin(req.headers),
request: req,
bodySizeLimit: body_size_limit
});
} catch (err) {
res.statusCode = err.status || 400;
res.end('Invalid request body');
return;
}
setResponse(
res,
await server.respond(request, {
platform: { req },
getClientAddress: () => {
if (address_header) {
if (!(address_header in req.headers)) {
throw new Error(
`Address header was specified with ${
ENV_PREFIX + 'ADDRESS_HEADER'
}=${address_header} but is absent from request`
);
}
const value = /** @type {string} */ (req.headers[address_header]) || '';
if (address_header === 'x-forwarded-for') {
const addresses = value.split(',');
if (xff_depth < 1) {
throw new Error(`${ENV_PREFIX + 'XFF_DEPTH'} must be a positive integer`);
}
if (xff_depth > addresses.length) {
throw new Error(
`${ENV_PREFIX + 'XFF_DEPTH'} is ${xff_depth}, but only found ${
addresses.length
} addresses`
);
}
return addresses[addresses.length - xff_depth].trim();
}
return value;
}
return (
req.connection?.remoteAddress ||
// @ts-expect-error
req.connection?.socket?.remoteAddress ||
req.socket?.remoteAddress ||
// @ts-expect-error
req.info?.remoteAddress
);
}
})
);
};
/** @param {import('polka').Middleware[]} handlers */
function sequence(handlers) {
/** @type {import('polka').Middleware} */
return (req, res, next) => {
/**
* @param {number} i
* @returns {ReturnType<import('polka').Middleware>}
*/
function handle(i) {
if (i < handlers.length) {
return handlers[i](req, res, () => handle(i + 1));
} else {
return next();
}
}
return handle(0);
};
}
/**
* @param {import('http').IncomingHttpHeaders} headers
* @returns
*/
function get_origin(headers) {
const protocol = (protocol_header && headers[protocol_header]) || 'https';
const host = headers[host_header];
return `${protocol}://${host}`;
}
export const handler = sequence(
[
serve(path.join(dir, 'client'), true),
serve(path.join(dir, 'static')),
serve_prerendered(),
ssr
].filter(Boolean)
);