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http-proxy-middleware.js
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Sat, Dec 14, 16:45

http-proxy-middleware.js
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"use strict";
Object.defineProperty(exports, "__esModule", { value: true });
exports.HttpProxyMiddleware = void 0;
const httpProxy = require("http-proxy");
const config_factory_1 = require("./config-factory");
const contextMatcher = require("./context-matcher");
const handlers = require("./_handlers");
const logger_1 = require("./logger");
const PathRewriter = require("./path-rewriter");
const Router = require("./router");
class HttpProxyMiddleware {
constructor(context, opts) {
this.logger = (0, logger_1.getInstance)();
this.wsInternalSubscribed = false;
this.serverOnCloseSubscribed = false;
// https://github.com/Microsoft/TypeScript/wiki/'this'-in-TypeScript#red-flags-for-this
this.middleware = async (req, res, next) => {
var _a, _b;
if (this.shouldProxy(this.config.context, req)) {
try {
const activeProxyOptions = await this.prepareProxyRequest(req);
this.proxy.web(req, res, activeProxyOptions);
}
catch (err) {
next(err);
}
}
else {
next();
}
/**
* Get the server object to subscribe to server events;
* 'upgrade' for websocket and 'close' for graceful shutdown
*
* NOTE:
* req.socket: node >= 13
* req.connection: node < 13 (Remove this when node 12/13 support is dropped)
*/
const server = (_b = ((_a = req.socket) !== null && _a !== void 0 ? _a : req.connection)) === null || _b === void 0 ? void 0 : _b.server;
if (server && !this.serverOnCloseSubscribed) {
server.on('close', () => {
this.logger.info('[HPM] server close signal received: closing proxy server');
this.proxy.close();
});
this.serverOnCloseSubscribed = true;
}
if (this.proxyOptions.ws === true) {
// use initial request to access the server object to subscribe to http upgrade event
this.catchUpgradeRequest(server);
}
};
this.catchUpgradeRequest = (server) => {
if (!this.wsInternalSubscribed) {
server.on('upgrade', this.handleUpgrade);
// prevent duplicate upgrade handling;
// in case external upgrade is also configured
this.wsInternalSubscribed = true;
}
};
this.handleUpgrade = async (req, socket, head) => {
if (this.shouldProxy(this.config.context, req)) {
const activeProxyOptions = await this.prepareProxyRequest(req);
this.proxy.ws(req, socket, head, activeProxyOptions);
this.logger.info('[HPM] Upgrading to WebSocket');
}
};
/**
* Determine whether request should be proxied.
*
* @private
* @param {String} context [description]
* @param {Object} req [description]
* @return {Boolean}
*/
this.shouldProxy = (context, req) => {
const path = req.originalUrl || req.url;
return contextMatcher.match(context, path, req);
};
/**
* Apply option.router and option.pathRewrite
* Order matters:
* Router uses original path for routing;
* NOT the modified path, after it has been rewritten by pathRewrite
* @param {Object} req
* @return {Object} proxy options
*/
this.prepareProxyRequest = async (req) => {
// https://github.com/chimurai/http-proxy-middleware/issues/17
// https://github.com/chimurai/http-proxy-middleware/issues/94
req.url = req.originalUrl || req.url;
// store uri before it gets rewritten for logging
const originalPath = req.url;
const newProxyOptions = Object.assign({}, this.proxyOptions);
// Apply in order:
// 1. option.router
// 2. option.pathRewrite
await this.applyRouter(req, newProxyOptions);
await this.applyPathRewrite(req, this.pathRewriter);
// debug logging for both http(s) and websockets
if (this.proxyOptions.logLevel === 'debug') {
const arrow = (0, logger_1.getArrow)(originalPath, req.url, this.proxyOptions.target, newProxyOptions.target);
this.logger.debug('[HPM] %s %s %s %s', req.method, originalPath, arrow, newProxyOptions.target);
}
return newProxyOptions;
};
// Modify option.target when router present.
this.applyRouter = async (req, options) => {
let newTarget;
if (options.router) {
newTarget = await Router.getTarget(req, options);
if (newTarget) {
this.logger.debug('[HPM] Router new target: %s -> "%s"', options.target, newTarget);
options.target = newTarget;
}
}
};
// rewrite path
this.applyPathRewrite = async (req, pathRewriter) => {
if (pathRewriter) {
const path = await pathRewriter(req.url, req);
if (typeof path === 'string') {
req.url = path;
}
else {
this.logger.info('[HPM] pathRewrite: No rewritten path found. (%s)', req.url);
}
}
};
this.logError = (err, req, res, target) => {
var _a;
const hostname = ((_a = req.headers) === null || _a === void 0 ? void 0 : _a.host) || req.hostname || req.host; // (websocket) || (node0.10 || node 4/5)
const requestHref = `${hostname}${req.url}`;
const targetHref = `${target === null || target === void 0 ? void 0 : target.href}`; // target is undefined when websocket errors
const errorMessage = '[HPM] Error occurred while proxying request %s to %s [%s] (%s)';
const errReference = 'https://nodejs.org/api/errors.html#errors_common_system_errors'; // link to Node Common Systems Errors page
this.logger.error(errorMessage, requestHref, targetHref, err.code || err, errReference);
};
this.config = (0, config_factory_1.createConfig)(context, opts);
this.proxyOptions = this.config.options;
// create proxy
this.proxy = httpProxy.createProxyServer({});
this.logger.info(`[HPM] Proxy created: ${this.config.context} -> ${this.proxyOptions.target}`);
this.pathRewriter = PathRewriter.createPathRewriter(this.proxyOptions.pathRewrite); // returns undefined when "pathRewrite" is not provided
// attach handler to http-proxy events
handlers.init(this.proxy, this.proxyOptions);
// log errors for debug purpose
this.proxy.on('error', this.logError);
// https://github.com/chimurai/http-proxy-middleware/issues/19
// expose function to upgrade externally
this.middleware.upgrade = (req, socket, head) => {
if (!this.wsInternalSubscribed) {
this.handleUpgrade(req, socket, head);
}
};
}
}
exports.HttpProxyMiddleware = HttpProxyMiddleware;

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