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middleware.js
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Fri, Feb 14, 07:49

middleware.js
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"use strict";
const path = require("path");
const mime = require("mime-types");
const parseRange = require("range-parser");
const getFilenameFromUrl = require("./utils/getFilenameFromUrl");
const {
getHeaderNames,
getHeaderFromRequest,
getHeaderFromResponse,
setHeaderForResponse,
setStatusCode,
send
} = require("./utils/compatibleAPI");
const ready = require("./utils/ready");
/** @typedef {import("./index.js").NextFunction} NextFunction */
/** @typedef {import("./index.js").IncomingMessage} IncomingMessage */
/** @typedef {import("./index.js").ServerResponse} ServerResponse */
/**
* @param {string} type
* @param {number} size
* @param {import("range-parser").Range} [range]
* @returns {string}
*/
function getValueContentRangeHeader(type, size, range) {
return `${type} ${range ? `${range.start}-${range.end}` : "*"}/${size}`;
}
/**
* @param {string | number} title
* @param {string} body
* @returns {string}
*/
function createHtmlDocument(title, body) {
return `${"<!DOCTYPE html>\n" + '<html lang="en">\n' + "<head>\n" + '<meta charset="utf-8">\n' + "<title>"}${title}</title>\n` + `</head>\n` + `<body>\n` + `<pre>${body}</pre>\n` + `</body>\n` + `</html>\n`;
}
const BYTES_RANGE_REGEXP = /^ *bytes/i;
/**
* @template {IncomingMessage} Request
* @template {ServerResponse} Response
* @param {import("./index.js").Context<Request, Response>} context
* @return {import("./index.js").Middleware<Request, Response>}
*/
function wrapper(context) {
return async function middleware(req, res, next) {
const acceptedMethods = context.options.methods || ["GET", "HEAD"]; // fixes #282. credit @cexoso. in certain edge situations res.locals is undefined.
// eslint-disable-next-line no-param-reassign
res.locals = res.locals || {};
if (req.method && !acceptedMethods.includes(req.method)) {
await goNext();
return;
}
ready(context, processRequest, req);
async function goNext() {
if (!context.options.serverSideRender) {
return next();
}
return new Promise(resolve => {
ready(context, () => {
/** @type {any} */
// eslint-disable-next-line no-param-reassign
res.locals.webpack = {
devMiddleware: context
};
resolve(next());
}, req);
});
}
async function processRequest() {
const filename = getFilenameFromUrl(context,
/** @type {string} */
req.url);
if (!filename) {
await goNext();
return;
}
let {
headers
} = context.options;
if (typeof headers === "function") {
// @ts-ignore
headers = headers(req, res, context);
}
/**
* @type {{key: string, value: string | number}[]}
*/
const allHeaders = [];
if (typeof headers !== "undefined") {
if (!Array.isArray(headers)) {
// eslint-disable-next-line guard-for-in
for (const name in headers) {
// @ts-ignore
allHeaders.push({
key: name,
value: headers[name]
});
}
headers = allHeaders;
}
headers.forEach(
/**
* @param {{key: string, value: any}} header
*/
header => {
setHeaderForResponse(res, header.key, header.value);
});
}
if (!getHeaderFromResponse(res, "Content-Type")) {
// content-type name(like application/javascript; charset=utf-8) or false
const contentType = mime.contentType(path.extname(filename)); // Only set content-type header if media type is known
// https://tools.ietf.org/html/rfc7231#section-3.1.1.5
if (contentType) {
setHeaderForResponse(res, "Content-Type", contentType);
}
}
if (!getHeaderFromResponse(res, "Accept-Ranges")) {
setHeaderForResponse(res, "Accept-Ranges", "bytes");
}
const rangeHeader = getHeaderFromRequest(req, "range");
let start;
let end;
if (rangeHeader && BYTES_RANGE_REGEXP.test(rangeHeader)) {
const size = await new Promise(resolve => {
/** @type {import("fs").lstat} */
context.outputFileSystem.lstat(filename, (error, stats) => {
if (error) {
context.logger.error(error);
return;
}
resolve(stats.size);
});
});
const parsedRanges = parseRange(size, rangeHeader, {
combine: true
});
if (parsedRanges === -1) {
const message = "Unsatisfiable range for 'Range' header.";
context.logger.error(message);
const existingHeaders = getHeaderNames(res);
for (let i = 0; i < existingHeaders.length; i++) {
res.removeHeader(existingHeaders[i]);
}
setStatusCode(res, 416);
setHeaderForResponse(res, "Content-Range", getValueContentRangeHeader("bytes", size));
setHeaderForResponse(res, "Content-Type", "text/html; charset=utf-8");
const document = createHtmlDocument(416, `Error: ${message}`);
const byteLength = Buffer.byteLength(document);
setHeaderForResponse(res, "Content-Length", Buffer.byteLength(document));
send(req, res, document, byteLength);
return;
} else if (parsedRanges === -2) {
context.logger.error("A malformed 'Range' header was provided. A regular response will be sent for this request.");
} else if (parsedRanges.length > 1) {
context.logger.error("A 'Range' header with multiple ranges was provided. Multiple ranges are not supported, so a regular response will be sent for this request.");
}
if (parsedRanges !== -2 && parsedRanges.length === 1) {
// Content-Range
setStatusCode(res, 206);
setHeaderForResponse(res, "Content-Range", getValueContentRangeHeader("bytes", size,
/** @type {import("range-parser").Ranges} */
parsedRanges[0]));
[{
start,
end
}] = parsedRanges;
}
}
const isFsSupportsStream = typeof context.outputFileSystem.createReadStream === "function";
let bufferOtStream;
let byteLength;
try {
if (typeof start !== "undefined" && typeof end !== "undefined" && isFsSupportsStream) {
bufferOtStream =
/** @type {import("fs").createReadStream} */
context.outputFileSystem.createReadStream(filename, {
start,
end
});
byteLength = end - start + 1;
} else {
bufferOtStream =
/** @type {import("fs").readFileSync} */
context.outputFileSystem.readFileSync(filename);
({
byteLength
} = bufferOtStream);
}
} catch (_ignoreError) {
await goNext();
return;
}
send(req, res, bufferOtStream, byteLength);
}
};
}
module.exports = wrapper;

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