react-native-mosquito-transport
Version:
React native javascript sdk for mosquito-transport (https://github.com/brainbehindx/mosquito-transport)
60 lines (54 loc) • 1.95 kB
JavaScript
// this file was sourced from https://github.com/websockets/utf-8-validate/blob/v6.0.5/fallback.js
/**
* Checks if a given buffer contains only correct UTF-8.
* Ported from https://www.cl.cam.ac.uk/%7Emgk25/ucs/utf8_check.c by
* Markus Kuhn.
*
* @param {Buffer} buf The buffer to check
* @return {Boolean} `true` if `buf` contains only correct UTF-8, else `false`
* @public
*/
export default function isValidUTF8(buf) {
const len = buf.length;
let i = 0;
while (i < len) {
if ((buf[i] & 0x80) === 0x00) { // 0xxxxxxx
i++;
} else if ((buf[i] & 0xe0) === 0xc0) { // 110xxxxx 10xxxxxx
if (
i + 1 === len ||
(buf[i + 1] & 0xc0) !== 0x80 ||
(buf[i] & 0xfe) === 0xc0 // overlong
) {
return false;
}
i += 2;
} else if ((buf[i] & 0xf0) === 0xe0) { // 1110xxxx 10xxxxxx 10xxxxxx
if (
i + 2 >= len ||
(buf[i + 1] & 0xc0) !== 0x80 ||
(buf[i + 2] & 0xc0) !== 0x80 ||
buf[i] === 0xe0 && (buf[i + 1] & 0xe0) === 0x80 || // overlong
buf[i] === 0xed && (buf[i + 1] & 0xe0) === 0xa0 // surrogate (U+D800 - U+DFFF)
) {
return false;
}
i += 3;
} else if ((buf[i] & 0xf8) === 0xf0) { // 11110xxx 10xxxxxx 10xxxxxx 10xxxxxx
if (
i + 3 >= len ||
(buf[i + 1] & 0xc0) !== 0x80 ||
(buf[i + 2] & 0xc0) !== 0x80 ||
(buf[i + 3] & 0xc0) !== 0x80 ||
buf[i] === 0xf0 && (buf[i + 1] & 0xf0) === 0x80 || // overlong
buf[i] === 0xf4 && buf[i + 1] > 0x8f || buf[i] > 0xf4 // > U+10FFFF
) {
return false;
}
i += 4;
} else {
return false;
}
}
return true;
}