mirror of
https://github.com/hanzoai/utf-8-validate.git
synced 2026-09-24 17:03:57 +00:00
Luigi Pinca
19508d6c84
The function is always called with a buffer in ws so we don't need to validate the argument. Type checking can be done in JavaScript, before calling the function, if needed.
69 lines
1.8 KiB
JavaScript
69 lines
1.8 KiB
JavaScript
/*!
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* UTF-8 validate: UTF-8 validation for WebSockets.
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* Copyright(c) 2015 Einar Otto Stangvik <[email protected]>
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* MIT Licensed
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*/
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'use strict';
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/**
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* Checks if a given buffer contains only correct UTF-8.
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* Ported from https://www.cl.cam.ac.uk/%7Emgk25/ucs/utf8_check.c by
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* Markus Kuhn.
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*
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* @param {Buffer} buf The buffer to check
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* @return {Boolean} `true` if `buf` contains only correct UTF-8, else `false`
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* @public
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*/
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const isValidUTF8 = (buf) => {
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var len = buf.length;
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var i = 0;
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while (i < len) {
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if (buf[i] < 0x80) { // 0xxxxxxx
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i++;
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} else if ((buf[i] & 0xe0) === 0xc0) { // 110xxxxx 10xxxxxx
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if (
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i + 1 === len ||
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(buf[i + 1] & 0xc0) !== 0x80 ||
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(buf[i] & 0xfe) === 0xc0 // overlong
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) {
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return false;
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} else {
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i += 2;
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}
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} else if ((buf[i] & 0xf0) === 0xe0) { // 1110xxxx 10xxxxxx 10xxxxxx
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if (
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i + 2 >= len ||
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(buf[i + 1] & 0xc0) !== 0x80 ||
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(buf[i + 2] & 0xc0) !== 0x80 ||
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buf[i] === 0xe0 && (buf[i + 1] & 0xe0) === 0x80 || // overlong
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buf[i] === 0xed && (buf[i + 1] & 0xe0) === 0xa0 // surrogate (U+D800 - U+DFFF)
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) {
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return false;
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} else {
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i += 3;
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}
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} else if ((buf[i] & 0xf8) === 0xf0) { // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
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if (
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i + 3 >= len ||
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(buf[i + 1] & 0xc0) !== 0x80 ||
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(buf[i + 2] & 0xc0) !== 0x80 ||
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(buf[i + 3] & 0xc0) !== 0x80 ||
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buf[i] === 0xf0 && (buf[i + 1] & 0xf0) === 0x80 || // overlong
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buf[i] === 0xf4 && buf[i + 1] > 0x8f || buf[i] > 0xf4 // > U+10FFFF
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) {
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return false;
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} else {
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i += 4;
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}
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} else {
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return false;
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}
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}
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return true;
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};
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module.exports = isValidUTF8;
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