index.js
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var url = require("url");
var URL = url.URL;
var http = require("http");
var https = require("https");
var assert = require("assert");
var Writable = require("stream").Writable;
var debug = require("debug")("follow-redirects");
// RFC7231§4.2.1: Of the request methods defined by this specification,
// the GET, HEAD, OPTIONS, and TRACE methods are defined to be safe.
var SAFE_METHODS = { GET: true, HEAD: true, OPTIONS: true, TRACE: true };
// Create handlers that pass events from native requests
var eventHandlers = Object.create(null);
["abort", "aborted", "error", "socket", "timeout"].forEach(function (event) {
eventHandlers[event] = function (arg) {
this._redirectable.emit(event, arg);
};
});
// An HTTP(S) request that can be redirected
function RedirectableRequest(options, responseCallback) {
// Initialize the request
Writable.call(this);
options.headers = options.headers || {};
this._options = options;
this._ended = false;
this._ending = false;
this._redirectCount = 0;
this._redirects = [];
this._requestBodyLength = 0;
this._requestBodyBuffers = [];
// 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;
}
// 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);
};
// 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);
}
}
// Perform the first request
this._performRequest();
}
RedirectableRequest.prototype = Object.create(Writable.prototype);
// 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 Error("write after end");
}
// Validate input and shift parameters if necessary
if (!(typeof data === "string" || typeof data === "object" && ("length" in data))) {
throw new Error("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 Error("Request body larger than maxBodyLength limit"));
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) {
if (callback) {
this.once("timeout", callback);
}
if (this.socket) {
startTimer(this, msecs);
}
else {
var self = this;
this._currentRequest.once("socket", function () {
startTimer(self, msecs);
});
}
this.once("response", clearTimer);
this.once("error", clearTimer);
return this;
};
function startTimer(request, msecs) {
clearTimeout(request._timeout);
request._timeout = setTimeout(function () {
request.emit("timeout");
}, msecs);
}
function clearTimer() {
clearTimeout(this._timeout);
}
// Proxy all other public ClientRequest methods
[
"abort", "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]; },
});
});
// 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 Error("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 event in eventHandlers) {
/* istanbul ignore else */
if (event) {
request.on(event, eventHandlers[event]);
}
}
// 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
if (this._options.trackRedirects) {
this._redirects.push({
url: this._currentUrl,
headers: response.headers,
statusCode: response.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 &&
response.statusCode >= 300 && response.statusCode < 400) {
// Abort the current request
this._currentRequest.removeAllListeners();
this._currentRequest.on("error", noop);
this._currentRequest.abort();
// 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 Error("Max redirects exceeded."));
return;
}
// RFC7231§6.4: Automatic redirection needs to done with
// care for methods not known to be safe […],
// since the user might not wish to redirect an unsafe request.
// RFC7231§6.4.7: The 307 (Temporary Redirect) status code indicates
// that the target resource resides temporarily under a different URI
// and the user agent MUST NOT change the request method
// if it performs an automatic redirection to that URI.
var header;
var headers = this._options.headers;
if (response.statusCode !== 307 && !(this._options.method in SAFE_METHODS)) {
this._options.method = "GET";
// Drop a possible entity and headers related to it
this._requestBodyBuffers = [];
for (header in headers) {
if (/^content-/i.test(header)) {
delete headers[header];
}
}
}
// Drop the Host header, as the redirect might lead to a different host
if (!this._isRedirect) {
for (header in headers) {
if (/^host$/i.test(header)) {
delete headers[header];
}
}
}
// Perform the redirected request
var redirectUrl = url.resolve(this._currentUrl, location);
debug("redirecting to", redirectUrl);
Object.assign(this._options, url.parse(redirectUrl));
this._isRedirect = true;
this._performRequest();
// Discard the remainder of the response to avoid waiting for data
response.destroy();
}
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
wrappedProtocol.request = function (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
wrappedProtocol.get = function (input, options, callback) {
var request = wrappedProtocol.request(input, options, callback);
request.end();
return request;
};
});
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;
}
// Exports
module.exports = wrap({ http: http, https: https });
module.exports.wrap = wrap;