98 lines
2.2 KiB
JavaScript
98 lines
2.2 KiB
JavaScript
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"use strict";
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/**
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* Check if the code point is a digit [0-9]
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*
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* @param {number} code
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* @return boolean
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*/
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function isDigit(code) {
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// 48 == '0'
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// 57 == '9'
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return code >= 48 && code <= 57;
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}
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/**
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* Check if the code point is a letter [a-zA-Z]
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*
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* @param {number} code
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* @return boolean
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*/
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function isAlpha(code) {
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// 97 === 'a'
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// 122 == 'z'
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return code >= 97 && code <= 122;
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}
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/**
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* Check if a hostname string is valid (according to RFC). It's usually a
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* preliminary check before trying to use getDomain or anything else.
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*
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* Beware: it does not check if the TLD exists.
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*
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* @api
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* @param {string} hostname
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* @return {boolean}
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*/
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module.exports = function isValid(hostname) {
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if (typeof hostname !== 'string') {
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return false;
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}
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if (hostname.length > 255) {
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return false;
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}
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if (hostname.length === 0) {
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return false;
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}
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// Check first character: [a-zA-Z0-9]
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var firstCharCode = hostname.charCodeAt(0);
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if (!(isAlpha(firstCharCode) || isDigit(firstCharCode))) {
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return false;
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}
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// Validate hostname according to RFC
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var lastDotIndex = -1;
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var lastCharCode;
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var code;
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var len = hostname.length;
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for (var i = 0; i < len; i += 1) {
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code = hostname.charCodeAt(i);
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if (code === 46) { // '.'
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if (
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// Check that previous label is < 63 bytes long (64 = 63 + '.')
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(i - lastDotIndex) > 64 ||
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// Check that previous character was not already a '.'
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lastCharCode === 46 ||
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// Check that the previous label does not end with a '-'
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lastCharCode === 45
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) {
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return false;
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}
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lastDotIndex = i;
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} else if (!(isAlpha(code) || isDigit(code) || code === 45)) {
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// Check if there is a forbidden character in the label: [^a-zA-Z0-9-]
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return false;
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}
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lastCharCode = code;
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}
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return (
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// Check that last label is shorter than 63 chars
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(len - lastDotIndex - 1) <= 63 &&
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// Check that the last character is an allowed trailing label character.
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// Since we already checked that the char is a valid hostname character,
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// we only need to check that it's different from '-'.
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lastCharCode !== 45
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);
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};
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