1 files changed, 531 insertions, 0 deletions
diff --git a/follow-redirects/index.js b/follow-redirects/index.js
new file mode 100644
index 0000000..8ac500e
--- /dev/null
+++ b/follow-redirects/index.js
@@ -0,0 +1,531 @@
+var url = require("url");
+var URL = url.URL;
+var http = require("http");
+var https = require("https");
+var Writable = require("stream").Writable;
+var assert = require("assert");
+var debug = require("./debug");
+
+// Create handlers that pass events from native requests
+var events = ["abort", "aborted", "connect", "error", "socket", "timeout"];
+var eventHandlers = Object.create(null);
+events.forEach(function (event) {
+  eventHandlers[event] = function (arg1, arg2, arg3) {
+    this._redirectable.emit(event, arg1, arg2, arg3);
+  };
+});
+
+// Error types with codes
+var RedirectionError = createErrorType(
+  "ERR_FR_REDIRECTION_FAILURE",
+  ""
+);
+var TooManyRedirectsError = createErrorType(
+  "ERR_FR_TOO_MANY_REDIRECTS",
+  "Maximum number of redirects exceeded"
+);
+var MaxBodyLengthExceededError = createErrorType(
+  "ERR_FR_MAX_BODY_LENGTH_EXCEEDED",
+  "Request body larger than maxBodyLength limit"
+);
+var WriteAfterEndError = createErrorType(
+  "ERR_STREAM_WRITE_AFTER_END",
+  "write after end"
+);
+
+// An HTTP(S) request that can be redirected
+function RedirectableRequest(options, responseCallback) {
+  // Initialize the request
+  Writable.call(this);
+  this._sanitizeOptions(options);
+  this._options = options;
+  this._ended = false;
+  this._ending = false;
+  this._redirectCount = 0;
+  this._redirects = [];
+  this._requestBodyLength = 0;
+  this._requestBodyBuffers = [];
+
+  // Attach a callback if passed
+  if (responseCallback) {
+    this.on("response", responseCallback);
+  }
+
+  // React to responses of native requests
+  var self = this;
+  this._onNativeResponse = function (response) {
+    self._processResponse(response);
+  };
+
+  // Perform the first request
+  this._performRequest();
+}
+RedirectableRequest.prototype = Object.create(Writable.prototype);
+
+RedirectableRequest.prototype.abort = function () {
+  abortRequest(this._currentRequest);
+  this.emit("abort");
+};
+
+// Writes buffered data to the current native request
+RedirectableRequest.prototype.write = function (data, encoding, callback) {
+  // Writing is not allowed if end has been called
+  if (this._ending) {
+    throw new WriteAfterEndError();
+  }
+
+  // Validate input and shift parameters if necessary
+  if (!(typeof data === "string" || typeof data === "object" && ("length" in data))) {
+    throw new TypeError("data should be a string, Buffer or Uint8Array");
+  }
+  if (typeof encoding === "function") {
+    callback = encoding;
+    encoding = null;
+  }
+
+  // Ignore empty buffers, since writing them doesn't invoke the callback
+  // https://github.com/nodejs/node/issues/22066
+  if (data.length === 0) {
+    if (callback) {
+      callback();
+    }
+    return;
+  }
+  // Only write when we don't exceed the maximum body length
+  if (this._requestBodyLength + data.length <= this._options.maxBodyLength) {
+    this._requestBodyLength += data.length;
+    this._requestBodyBuffers.push({ data: data, encoding: encoding });
+    this._currentRequest.write(data, encoding, callback);
+  }
+  // Error when we exceed the maximum body length
+  else {
+    this.emit("error", new MaxBodyLengthExceededError());
+    this.abort();
+  }
+};
+
+// Ends the current native request
+RedirectableRequest.prototype.end = function (data, encoding, callback) {
+  // Shift parameters if necessary
+  if (typeof data === "function") {
+    callback = data;
+    data = encoding = null;
+  }
+  else if (typeof encoding === "function") {
+    callback = encoding;
+    encoding = null;
+  }
+
+  // Write data if needed and end
+  if (!data) {
+    this._ended = this._ending = true;
+    this._currentRequest.end(null, null, callback);
+  }
+  else {
+    var self = this;
+    var currentRequest = this._currentRequest;
+    this.write(data, encoding, function () {
+      self._ended = true;
+      currentRequest.end(null, null, callback);
+    });
+    this._ending = true;
+  }
+};
+
+// Sets a header value on the current native request
+RedirectableRequest.prototype.setHeader = function (name, value) {
+  this._options.headers[name] = value;
+  this._currentRequest.setHeader(name, value);
+};
+
+// Clears a header value on the current native request
+RedirectableRequest.prototype.removeHeader = function (name) {
+  delete this._options.headers[name];
+  this._currentRequest.removeHeader(name);
+};
+
+// Global timeout for all underlying requests
+RedirectableRequest.prototype.setTimeout = function (msecs, callback) {
+  var self = this;
+  if (callback) {
+    this.on("timeout", callback);
+  }
+
+  function destroyOnTimeout(socket) {
+    socket.setTimeout(msecs);
+    socket.removeListener("timeout", socket.destroy);
+    socket.addListener("timeout", socket.destroy);
+  }
+
+  // Sets up a timer to trigger a timeout event
+  function startTimer(socket) {
+    if (self._timeout) {
+      clearTimeout(self._timeout);
+    }
+    self._timeout = setTimeout(function () {
+      self.emit("timeout");
+      clearTimer();
+    }, msecs);
+    destroyOnTimeout(socket);
+  }
+
+  // Prevent a timeout from triggering
+  function clearTimer() {
+    clearTimeout(this._timeout);
+    if (callback) {
+      self.removeListener("timeout", callback);
+    }
+    if (!this.socket) {
+      self._currentRequest.removeListener("socket", startTimer);
+    }
+  }
+
+  // Start the timer when the socket is opened
+  if (this.socket) {
+    startTimer(this.socket);
+  }
+  else {
+    this._currentRequest.once("socket", startTimer);
+  }
+
+  this.on("socket", destroyOnTimeout);
+  this.once("response", clearTimer);
+  this.once("error", clearTimer);
+
+  return this;
+};
+
+// Proxy all other public ClientRequest methods
+[
+  "flushHeaders", "getHeader",
+  "setNoDelay", "setSocketKeepAlive",
+].forEach(function (method) {
+  RedirectableRequest.prototype[method] = function (a, b) {
+    return this._currentRequest[method](a, b);
+  };
+});
+
+// Proxy all public ClientRequest properties
+["aborted", "connection", "socket"].forEach(function (property) {
+  Object.defineProperty(RedirectableRequest.prototype, property, {
+    get: function () { return this._currentRequest[property]; },
+  });
+});
+
+RedirectableRequest.prototype._sanitizeOptions = function (options) {
+  // Ensure headers are always present
+  if (!options.headers) {
+    options.headers = {};
+  }
+
+  // Since http.request treats host as an alias of hostname,
+  // but the url module interprets host as hostname plus port,
+  // eliminate the host property to avoid confusion.
+  if (options.host) {
+    // Use hostname if set, because it has precedence
+    if (!options.hostname) {
+      options.hostname = options.host;
+    }
+    delete options.host;
+  }
+
+  // Complete the URL object when necessary
+  if (!options.pathname && options.path) {
+    var searchPos = options.path.indexOf("?");
+    if (searchPos < 0) {
+      options.pathname = options.path;
+    }
+    else {
+      options.pathname = options.path.substring(0, searchPos);
+      options.search = options.path.substring(searchPos);
+    }
+  }
+};
+
+
+// Executes the next native request (initial or redirect)
+RedirectableRequest.prototype._performRequest = function () {
+  // Load the native protocol
+  var protocol = this._options.protocol;
+  var nativeProtocol = this._options.nativeProtocols[protocol];
+  if (!nativeProtocol) {
+    this.emit("error", new TypeError("Unsupported protocol " + protocol));
+    return;
+  }
+
+  // If specified, use the agent corresponding to the protocol
+  // (HTTP and HTTPS use different types of agents)
+  if (this._options.agents) {
+    var scheme = protocol.substr(0, protocol.length - 1);
+    this._options.agent = this._options.agents[scheme];
+  }
+
+  // Create the native request
+  var request = this._currentRequest =
+        nativeProtocol.request(this._options, this._onNativeResponse);
+  this._currentUrl = url.format(this._options);
+
+  // Set up event handlers
+  request._redirectable = this;
+  for (var e = 0; e < events.length; e++) {
+    request.on(events[e], eventHandlers[events[e]]);
+  }
+
+  // End a redirected request
+  // (The first request must be ended explicitly with RedirectableRequest#end)
+  if (this._isRedirect) {
+    // Write the request entity and end.
+    var i = 0;
+    var self = this;
+    var buffers = this._requestBodyBuffers;
+    (function writeNext(error) {
+      // Only write if this request has not been redirected yet
+      /* istanbul ignore else */
+      if (request === self._currentRequest) {
+        // Report any write errors
+        /* istanbul ignore if */
+        if (error) {
+          self.emit("error", error);
+        }
+        // Write the next buffer if there are still left
+        else if (i < buffers.length) {
+          var buffer = buffers[i++];
+          /* istanbul ignore else */
+          if (!request.finished) {
+            request.write(buffer.data, buffer.encoding, writeNext);
+          }
+        }
+        // End the request if `end` has been called on us
+        else if (self._ended) {
+          request.end();
+        }
+      }
+    }());
+  }
+};
+
+// Processes a response from the current native request
+RedirectableRequest.prototype._processResponse = function (response) {
+  // Store the redirected response
+  var statusCode = response.statusCode;
+  if (this._options.trackRedirects) {
+    this._redirects.push({
+      url: this._currentUrl,
+      headers: response.headers,
+      statusCode: statusCode,
+    });
+  }
+
+  // RFC7231§6.4: The 3xx (Redirection) class of status code indicates
+  // that further action needs to be taken by the user agent in order to
+  // fulfill the request. If a Location header field is provided,
+  // the user agent MAY automatically redirect its request to the URI
+  // referenced by the Location field value,
+  // even if the specific status code is not understood.
+  var location = response.headers.location;
+  if (location && this._options.followRedirects !== false &&
+      statusCode >= 300 && statusCode < 400) {
+    // Abort the current request
+    abortRequest(this._currentRequest);
+    // Discard the remainder of the response to avoid waiting for data
+    response.destroy();
+
+    // RFC7231§6.4: A client SHOULD detect and intervene
+    // in cyclical redirections (i.e., "infinite" redirection loops).
+    if (++this._redirectCount > this._options.maxRedirects) {
+      this.emit("error", new TooManyRedirectsError());
+      return;
+    }
+
+    // RFC7231§6.4: Automatic redirection needs to done with
+    // care for methods not known to be safe, […]
+    // RFC7231§6.4.2–3: For historical reasons, a user agent MAY change
+    // the request method from POST to GET for the subsequent request.
+    if ((statusCode === 301 || statusCode === 302) && this._options.method === "POST" ||
+        // RFC7231§6.4.4: The 303 (See Other) status code indicates that
+        // the server is redirecting the user agent to a different resource […]
+        // A user agent can perform a retrieval request targeting that URI
+        // (a GET or HEAD request if using HTTP) […]
+        (statusCode === 303) && !/^(?:GET|HEAD)$/.test(this._options.method)) {
+      this._options.method = "GET";
+      // Drop a possible entity and headers related to it
+      this._requestBodyBuffers = [];
+      removeMatchingHeaders(/^content-/i, this._options.headers);
+    }
+
+    // Drop the Host header, as the redirect might lead to a different host
+    var previousHostName = removeMatchingHeaders(/^host$/i, this._options.headers) ||
+      url.parse(this._currentUrl).hostname;
+
+    // Create the redirected request
+    var redirectUrl = url.resolve(this._currentUrl, location);
+    debug("redirecting to", redirectUrl);
+    this._isRedirect = true;
+    var redirectUrlParts = url.parse(redirectUrl);
+    Object.assign(this._options, redirectUrlParts);
+
+    // Drop the Authorization header if redirecting to another host
+    if (redirectUrlParts.hostname !== previousHostName) {
+      removeMatchingHeaders(/^authorization$/i, this._options.headers);
+    }
+
+    // Evaluate the beforeRedirect callback
+    if (typeof this._options.beforeRedirect === "function") {
+      var responseDetails = { headers: response.headers };
+      try {
+        this._options.beforeRedirect.call(null, this._options, responseDetails);
+      }
+      catch (err) {
+        this.emit("error", err);
+        return;
+      }
+      this._sanitizeOptions(this._options);
+    }
+
+    // Perform the redirected request
+    try {
+      this._performRequest();
+    }
+    catch (cause) {
+      var error = new RedirectionError("Redirected request failed: " + cause.message);
+      error.cause = cause;
+      this.emit("error", error);
+    }
+  }
+  else {
+    // The response is not a redirect; return it as-is
+    response.responseUrl = this._currentUrl;
+    response.redirects = this._redirects;
+    this.emit("response", response);
+
+    // Clean up
+    this._requestBodyBuffers = [];
+  }
+};
+
+// Wraps the key/value object of protocols with redirect functionality
+function wrap(protocols) {
+  // Default settings
+  var exports = {
+    maxRedirects: 21,
+    maxBodyLength: 10 * 1024 * 1024,
+  };
+
+  // Wrap each protocol
+  var nativeProtocols = {};
+  Object.keys(protocols).forEach(function (scheme) {
+    var protocol = scheme + ":";
+    var nativeProtocol = nativeProtocols[protocol] = protocols[scheme];
+    var wrappedProtocol = exports[scheme] = Object.create(nativeProtocol);
+
+    // Executes a request, following redirects
+    function request(input, options, callback) {
+      // Parse parameters
+      if (typeof input === "string") {
+        var urlStr = input;
+        try {
+          input = urlToOptions(new URL(urlStr));
+        }
+        catch (err) {
+          /* istanbul ignore next */
+          input = url.parse(urlStr);
+        }
+      }
+      else if (URL && (input instanceof URL)) {
+        input = urlToOptions(input);
+      }
+      else {
+        callback = options;
+        options = input;
+        input = { protocol: protocol };
+      }
+      if (typeof options === "function") {
+        callback = options;
+        options = null;
+      }
+
+      // Set defaults
+      options = Object.assign({
+        maxRedirects: exports.maxRedirects,
+        maxBodyLength: exports.maxBodyLength,
+      }, input, options);
+      options.nativeProtocols = nativeProtocols;
+
+      assert.equal(options.protocol, protocol, "protocol mismatch");
+      debug("options", options);
+      return new RedirectableRequest(options, callback);
+    }
+
+    // Executes a GET request, following redirects
+    function get(input, options, callback) {
+      var wrappedRequest = wrappedProtocol.request(input, options, callback);
+      wrappedRequest.end();
+      return wrappedRequest;
+    }
+
+    // Expose the properties on the wrapped protocol
+    Object.defineProperties(wrappedProtocol, {
+      request: { value: request, configurable: true, enumerable: true, writable: true },
+      get: { value: get, configurable: true, enumerable: true, writable: true },
+    });
+  });
+  return exports;
+}
+
+/* istanbul ignore next */
+function noop() { /* empty */ }
+
+// from https://github.com/nodejs/node/blob/master/lib/internal/url.js
+function urlToOptions(urlObject) {
+  var options = {
+    protocol: urlObject.protocol,
+    hostname: urlObject.hostname.startsWith("[") ?
+      /* istanbul ignore next */
+      urlObject.hostname.slice(1, -1) :
+      urlObject.hostname,
+    hash: urlObject.hash,
+    search: urlObject.search,
+    pathname: urlObject.pathname,
+    path: urlObject.pathname + urlObject.search,
+    href: urlObject.href,
+  };
+  if (urlObject.port !== "") {
+    options.port = Number(urlObject.port);
+  }
+  return options;
+}
+
+function removeMatchingHeaders(regex, headers) {
+  var lastValue;
+  for (var header in headers) {
+    if (regex.test(header)) {
+      lastValue = headers[header];
+      delete headers[header];
+    }
+  }
+  return lastValue;
+}
+
+function createErrorType(code, defaultMessage) {
+  function CustomError(message) {
+    Error.captureStackTrace(this, this.constructor);
+    this.message = message || defaultMessage;
+  }
+  CustomError.prototype = new Error();
+  CustomError.prototype.constructor = CustomError;
+  CustomError.prototype.name = "Error [" + code + "]";
+  CustomError.prototype.code = code;
+  return CustomError;
+}
+
+function abortRequest(request) {
+  for (var e = 0; e < events.length; e++) {
+    request.removeListener(events[e], eventHandlers[events[e]]);
+  }
+  request.on("error", noop);
+  request.abort();
+}
+
+// Exports
+module.exports = wrap({ http: http, https: https });
+module.exports.wrap = wrap;