node-http-proxy/lib/http-proxy/common.js

const common   = exports,
      extend   = require('util')._extend,
      required = require('requires-port');

const upgradeHeader = /(^|,)\s*upgrade\s*($|,)/i,
      isSSL = /^https|wss/;

/**
 * Simple Regex for testing if protocol is https
 */
common.isSSL = isSSL;
/**
 * Copies the right headers from `options` and `req` to
 * `outgoing` which is then used to fire the proxied
 * request.
 *
 * Examples:
 *
 *    common.setupOutgoing(outgoing, options, req)
 *    // => { host: ..., hostname: ...}
 *
 * @param {Object} Outgoing Base object to be filled with required properties
 * @param {Object} Options Config object passed to the proxy
 * @param {ClientRequest} Req Request Object
 * @param {String} Forward String to select forward or target
 * 
 * @return {Object} Outgoing Object with all required properties set
 *
 * @api private
 */

common.setupOutgoing = function(outgoing, options, req, forward) {
  const target = options[forward || 'target'];
  const sslEnabled = isSSL.test(target.protocol)

  outgoing.port = target.port || (sslEnabled ? 443 : 80);

  ['host', 'hostname', 'socketPath', 'pfx', 'key',
    'passphrase', 'cert', 'ca', 'ciphers', 'secureProtocol'].forEach(
    function(e) { outgoing[e] = target[e]; }
  );

  outgoing.method = options.method || req.method;
  outgoing.headers = extend({}, req.headers);

  if (options.headers) {
    extend(outgoing.headers, options.headers);
  }

  if (options.auth) {
    outgoing.auth = options.auth;
  }
  
  if (options.ca) {
    outgoing.ca = options.ca;
  }

  if (sslEnabled) {
    outgoing.rejectUnauthorized = (typeof options.secure === 'undefined') ? true : options.secure;
  }

  outgoing.agent = options.agent || false;
  outgoing.localAddress = options.localAddress;

  //
  // Remark: If we are false and not upgrading, set the connection: close. This is the right thing to do
  // as node core doesn't handle this COMPLETELY properly yet.
  //
  if (!outgoing.agent) {
    outgoing.headers = outgoing.headers || {};
    if (typeof outgoing.headers.connection !== 'string'
        || !upgradeHeader.test(outgoing.headers.connection)
       ) { outgoing.headers.connection = 'close'; }
  }


  // the final path is target path + relative path requested by user:
  const targetPath = target && options.prependPath !== false
    ? (target.pathname || '')
    : '';

  // Base just needs to resemble a valid URL,
  // we only care about the parsing of the path & params
  const reqUrl = new URL(req.url, 'http://doesntmatter.com')

  for(entry of target.searchParams.entries()) {
    reqUrl.searchParams.set(entry[0], entry[1])
  }

  const params = reqUrl.search
  
  let outgoingPath = !options.toProxy
    ? (reqUrl.pathname || '')
    : req.url;

  //
  // Remark: ignorePath will just straight up ignore whatever the request's
  // path is. This can be labeled as FOOT-GUN material if you do not know what
  // you are doing and are using conflicting options.
  //
  outgoingPath = !options.ignorePath ? outgoingPath : '';

  outgoing.path = [targetPath, outgoingPath].filter(Boolean).join('/').replace(/\/+/g, '/') + params

  if (options.changeOrigin) {
    outgoing.headers.host =
      required(outgoing.port, target.protocol) && !hasPort(outgoing.host)
        ? outgoing.host + ':' + outgoing.port
        : outgoing.host;
  }

  return outgoing;
};

/**
 * Set the proper configuration for sockets,
 * set no delay and set keep alive, also set
 * the timeout to 0.
 *
 * Examples:
 *
 *    common.setupSocket(socket)
 *    // => Socket
 *
 * @param {Socket} Socket instance to setup
 * 
 * @return {Socket} Return the configured socket.
 *
 * @api private
 */

common.setupSocket = function(socket) {
  socket.setTimeout(0);
  socket.setNoDelay(true);

  socket.setKeepAlive(true, 0);

  return socket;
};

/**
 * Get the port number from the host. Or guess it based on the connection type.
 *
 * @param {Request} req Incoming HTTP request.
 *
 * @return {String} The port number.
 *
 * @api private
 */
common.getPort = function(req) {
  const res = req.headers.host ? req.headers.host.match(/:(\d+)/) : '';

  return res ?
    res[1] :
    common.hasEncryptedConnection(req) ? '443' : '80';
};

/**
 * Check if the request has an encrypted connection.
 *
 * @param {Request} req Incoming HTTP request.
 *
 * @return {Boolean} Whether the connection is encrypted or not.
 *
 * @api private
 */
common.hasEncryptedConnection = function(req) {
  return Boolean(req.connection.encrypted || req.connection.pair);
};

/**
 * Rewrites or removes the domain of a cookie header
 *
 * @param {String|Array} Header
 * @param {Object} Config, mapping of domain to rewritten domain.
 *                 '*' key to match any domain, null value to remove the domain.
 *
 * @api private
 */
common.rewriteCookieProperty = function rewriteCookieProperty(header, config, property) {
  if (Array.isArray(header)) {
    return header.map(function (headerElement) {
      return rewriteCookieProperty(headerElement, config, property);
    });
  }
  return header.replace(new RegExp("(;\\s*" + property + "=)([^;]+)", 'i'), function(match, prefix, previousValue) {
    let newValue;
    if (previousValue in config) {
      newValue = config[previousValue];
    } else if ('*' in config) {
      newValue = config['*'];
    } else {
      //no match, return previous value
      return match;
    }
    if (newValue) {
      //replace value
      return prefix + newValue;
    } else {
      //remove value
      return '';
    }
  });
};

/**
 * Check the host and see if it potentially has a port in it (keep it simple)
 *
 * @returns {Boolean} Whether we have one or not
 *
 * @api private
 */
function hasPort(host) {
  return !!~host.indexOf(':');
};