116 lines
3.2 KiB
JavaScript
116 lines
3.2 KiB
JavaScript
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'use strict';
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/**
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* Polyfill for `endsWith`
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*
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* @param {string} str
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* @param {string} pattern
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* @return {boolean}
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*/
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function endsWith(str, pattern) {
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return (
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str.lastIndexOf(pattern) === (str.length - pattern.length)
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);
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}
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/**
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* Check if `vhost` is a valid suffix of `hostname` (top-domain)
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*
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* It means that `vhost` needs to be a suffix of `hostname` and we then need to
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* make sure that: either they are equal, or the character preceding `vhost` in
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* `hostname` is a '.' (it should not be a partial label).
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*
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* * hostname = 'not.evil.com' and vhost = 'vil.com' => not ok
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* * hostname = 'not.evil.com' and vhost = 'evil.com' => ok
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* * hostname = 'not.evil.com' and vhost = 'not.evil.com' => ok
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*
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* @param {string} hostname
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* @param {string} vhost
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* @return {boolean}
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*/
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function shareSameDomainSuffix(hostname, vhost) {
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if (endsWith(hostname, vhost)) {
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return (
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hostname.length === vhost.length ||
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hostname[hostname.length - vhost.length - 1] === '.'
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);
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}
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return false;
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}
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/**
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* Given a hostname and its public suffix, extract the general domain.
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*
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* @param {string} hostname
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* @param {string} publicSuffix
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* @return {string}
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*/
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function extractDomainWithSuffix(hostname, publicSuffix) {
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// Locate the index of the last '.' in the part of the `hostname` preceding
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// the public suffix.
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//
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// examples:
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// 1. not.evil.co.uk => evil.co.uk
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// ^ ^
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// | | start of public suffix
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// | index of the last dot
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//
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// 2. example.co.uk => example.co.uk
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// ^ ^
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// | | start of public suffix
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// |
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// | (-1) no dot found before the public suffix
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var publicSuffixIndex = hostname.length - publicSuffix.length - 2;
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var lastDotBeforeSuffixIndex = hostname.lastIndexOf('.', publicSuffixIndex);
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// No '.' found, then `hostname` is the general domain (no sub-domain)
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if (lastDotBeforeSuffixIndex === -1) {
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return hostname;
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}
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// Extract the part between the last '.'
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return hostname.substr(lastDotBeforeSuffixIndex + 1);
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}
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/**
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* Detects the domain based on rules and upon and a host string
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*
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* @api
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* @param {string} host
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* @return {String}
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*/
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module.exports = function getDomain(validHosts, suffix, hostname) {
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// Check if `hostname` ends with a member of `validHosts`.
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for (var i = 0; i < validHosts.length; i += 1) {
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var vhost = validHosts[i];
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if (shareSameDomainSuffix(hostname, vhost)) {
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return vhost;
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}
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}
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// If there is no suffix, there is no hostname
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if (suffix === null) {
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return null;
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}
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// If `hostname` is a valid public suffix, then there is no domain to return.
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// Since we already know that `getPublicSuffix` returns a suffix of `hostname`
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// there is no need to perform a string comparison and we only compare the
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// size.
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if (suffix.length === hostname.length) {
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return null;
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}
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// To extract the general domain, we start by identifying the public suffix
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// (if any), then consider the domain to be the public suffix with one added
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// level of depth. (e.g.: if hostname is `not.evil.co.uk` and public suffix:
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// `co.uk`, then we take one more level: `evil`, giving the final result:
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// `evil.co.uk`).
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return extractDomainWithSuffix(hostname, suffix);
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};
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