"use strict";
/*global require*/
var URI = require('urijs');
var defined = require('terriajs-cesium/Source/Core/defined');
var defaultValue = require('terriajs-cesium/Source/Core/defaultValue');
var loadJson = require('./loadJson');
var FeatureDetection = require('terriajs-cesium/Source/Core/FeatureDetection');
var DEFAULT_BASE_PROXY_PATH = 'proxy/';
/**
* Rewrites URLs so that they're resolved via the TerriaJS-Server proxy rather than going direct. This is most useful
* for getting around CORS restrictions on services that don't have CORS set up or when using pre-CORS browsers like IE9.
* Going via the proxy is also useful if you want to change the caching headers on map requests (for instance many map
* tile providers set cache headers to no-cache even for maps that rarely change, resulting in a much slower experience
* particularly on time-series data).
*
* @param overrideLoadJson A method for getting JSON from a URL that matches the signature of Core/loadJson
* module - this is overridable mainly for testing.
* @constructor
*/
function CorsProxy(overrideLoadJson) {
this.loadJson = defaultValue(overrideLoadJson, loadJson);
// Note that many of the following are intended to be set by a request to the server performed in {@link CorsProxy#init},
// but these can be overridden if necessary.
/**
* The base URL of the TerriaJS server proxy, to which requests will be appended. In most cases this is the server's
* host + '/proxy'.
* @type {String}
*/
this.baseProxyUrl = undefined;
/**
* Domains that should be proxied for, as set by config files. Stored as an array of hosts - if a TLD is specified,
* subdomains will also be proxied.
* @type {String[]}
*/
this.proxyDomains = undefined;
/**
* True if we expect that the proxy will proxy any URL - note that if the server isn't set up to do this, having
* this set to true will just result in a lot of failed AJAX calls
* @type {boolean}
*/
this.isOpenProxy = false;
/**
* Domains that are known to support CORS, as set by config files.
* @type {String[]}
*/
this.corsDomains = [];
/**
* Whether the proxy should be used regardless of whether the domain supports CORS or not. This defaults to true
* on IE<10.
* @type {boolean}
*/
this.alwaysUseProxy = FeatureDetection.isInternetExplorer() && FeatureDetection.internetExplorerVersion()[0] < 10; // IE versions prior to 10 don't support CORS, so always use the proxy.
/**
* Whether the page that Terria is running on is HTTPS. This is relevant because calling an HTTP domain from HTTPS
* results in mixed content warnings and going through the proxy is required to get around this.
* @type {boolean}
*/
this.pageIsHttps = typeof window !== 'undefined' && defined(window.location) && defined(window.location.href) && new URI(window.location.href).protocol() === 'https';
}
/**
* Initialises values with config previously loaded from server. This is the recommended way to use this object as it ensures
* the options will be correct for the proxy server it's configured to call, but this can be skipped and the values it
* initialises set manually if desired.
*
* @param {Object} serverConfig Configuration options retrieved from a ServerConfig object.
* @param {String} baseProxyUrl The base URL to proxy with - this will default to 'proxy/'
* @param {String[]} proxyDomains Initial value for proxyDomains to which proxyable domains from the server will be appended -
* defaults to an empty array.
* @returns {Promise} A promise that resolves when initialisation is complete.
*/
CorsProxy.prototype.init = function(serverConfig, baseProxyUrl, proxyDomains) {
this.baseProxyUrl = defaultValue(baseProxyUrl, DEFAULT_BASE_PROXY_PATH);
this.proxyDomains = defaultValue(proxyDomains, []);
if (serverConfig && typeof serverConfig === 'object') {
this.isOpenProxy = !! serverConfig.proxyAllDomains;
// ignore client list of allowed proxies in favour of definitive server list.
if (Array.isArray(serverConfig.allowProxyFor)) {
this.proxyDomains = serverConfig.allowProxyFor;
}
}
};
/**
* Determines if the proxying service should be used to access the given URL, based on our list of
* domains we're willing to proxy for and hosts that are known to support CORS.
*
* @param {String} url The url to examine.
* @return {Boolean} true if the proxy should be used, false if not.
*/
CorsProxy.prototype.shouldUseProxy = function(url) {
if (!defined(url)) {
// eg. no url may be passed if all data is embedded
return false;
}
var uri = new URI(url);
var host = uri.host();
if (host === '') {
// do not proxy local files
return false;
}
if (!this.isOpenProxy && !hostInDomains(host, this.proxyDomains)) {
// we're not willing to proxy for this host
return false;
}
if (this.alwaysUseProxy) {
return true;
}
if (this.pageIsHttps && uri.protocol() === 'http') {
// if we're accessing an http resource from an https page, always proxy in order to avoid a mixed content error.
return true;
}
if (hostInDomains(host, this.corsDomains)) {
// we don't need to proxy for this host, because it supports CORS
return false;
}
// we are ok with proxying for this host and we need to
return true;
};
/**
* Proxies a URL by appending it to {@link CorsProxy#baseProxyUrl}. Optionally inserts a proxyFlag that will override
* the cache headers of the response, allowing for caching to be added where it wouldn't otherwise.
*
* @param {String} resource the URL to potentially proxy
* @param {String} proxyFlag the proxy flag to pass - generally this is the length of time that you want to override
* the cache headers with. E.g. '2d' for 2 days.
* @returns {String} The proxied URL
*/
CorsProxy.prototype.getURL = function (resource, proxyFlag) {
var flag = (proxyFlag === undefined) ? '' : '_' + proxyFlag + '/';
return this.baseProxyUrl + flag + resource;
};
/**
* Convenience method that combines {@link CorsProxy#shouldUseProxy} and {@link getURL} - if the URL passed needs to be
* proxied according to the rules/config of the proxy, this will return a proxied URL, otherwise it will return the
* original URL.
*
* {@see CorsProxy#shouldUseProxy}
* {@see CorsProxy#getURL}
*
* @param {String} resource the URL to potentially proxy
* @param {String} proxyFlag the proxy flag to pass - generally this is the length of time that you want to override
* the cache headers with. E.g. '2d' for 2 days.
* @returns {String} Either the URL passed in or a proxied URL if it should be proxied.
*/
CorsProxy.prototype.getURLProxyIfNecessary = function (resource, proxyFlag) {
if (this.shouldUseProxy(resource)) {
return this.getURL(resource, proxyFlag);
}
return resource;
};
/**
* Determines whether this host is, or is a subdomain of, an item in the provided array.
*
* @param {String} host The host to search for
* @param {String[]} domains The array of domains to look in
* @returns {boolean} The result.
*/
function hostInDomains(host, domains) {
if (!defined(domains)) {
return false;
}
host = host.toLowerCase();
for (var i = 0; i < domains.length; i++) {
if (host.match("(^|\\.)" + domains[i] + "$")) {
return true;
}
}
return false;
}
module.exports = CorsProxy;