http-proxy-middleware
Version:
The one-liner node.js proxy middleware for connect, express, next.js and more
82 lines (81 loc) • 2.73 kB
JavaScript
import * as querystring from 'node:querystring';
import * as zlib from 'node:zlib';
/**
* Fix proxied body if bodyParser is involved.
*
* @example
* ```ts
* createProxyMiddleware({
* target: 'http://example.com',
* on: {
* proxyReq: fixRequestBody,
* }
* });
* ```
*
* Alternative solution without using `fixRequestBody()`: put `http-proxy-middleware` before `bodyParser` in the middleware stack.
*
* @see {@link https://github.com/chimurai/http-proxy-middleware/issues/40 Github issue #40 - POST request body is not proxied}
*/
export function fixRequestBody(proxyReq, req) {
// skip fixRequestBody() when req.readableLength not 0 (bodyParser failure)
if (req.readableLength !== 0) {
return;
}
const requestBody = req.body;
if (!requestBody) {
return;
}
const contentType = proxyReq.getHeader('Content-Type');
if (!contentType) {
return;
}
const writeBody = (bodyData) => {
let proxyData = bodyData;
const contentEncoding = String(proxyReq.getHeader('Content-Encoding')).toLowerCase();
switch (contentEncoding) {
case 'br':
proxyData = zlib.brotliCompressSync(proxyData);
break;
case 'deflate':
proxyData = zlib.deflateSync(proxyData);
break;
case 'gzip':
proxyData = zlib.gzipSync(proxyData);
break;
case 'zstd':
proxyData = zlib.zstdCompressSync(proxyData);
break;
}
proxyReq.setHeader('Content-Length', Buffer.byteLength(proxyData));
proxyReq.write(proxyData);
};
// Use if-elseif to prevent multiple writeBody/setHeader calls:
// Error: "Cannot set headers after they are sent to the client"
if (contentType.includes('application/json') || contentType.includes('+json')) {
writeBody(JSON.stringify(requestBody));
}
else if (contentType.includes('application/x-www-form-urlencoded')) {
writeBody(querystring.stringify(requestBody));
}
else if (contentType.includes('multipart/form-data')) {
writeBody(handlerFormDataBodyData(contentType, requestBody));
}
else if (contentType.includes('text/plain')) {
writeBody(requestBody);
}
}
/**
* format FormData data
* @param contentType
* @param data
* @returns
*/
function handlerFormDataBodyData(contentType, data) {
const boundary = contentType.replace(/^.*boundary=(.*)$/, '$1');
let str = '';
for (const [key, value] of Object.entries(data)) {
str += `--${boundary}\r\nContent-Disposition: form-data; name="${key}"\r\n\r\n${value}\r\n`;
}
return str;
}