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'use strict';
const { tokenChars } = require('./validation');
/**
* Parses the `Sec-WebSocket-Protocol` header into a set of subprotocol names.
*
* @param {String} header The field value of the header
* @return {Set} The subprotocol names
* @public
*/
function parse(header) {
const protocols = new Set();
let start = -1;
let end = -1;
let i = 0;
for (i; i < header.length; i++) {
const code = header.charCodeAt(i);
if (end === -1 && tokenChars[code] === 1) {
if (start === -1) start = i;
} else if (
i !== 0 &&
(code === 0x20 /* ' ' */ || code === 0x09) /* '\t' */
) {
if (end === -1 && start !== -1) end = i;
} else if (code === 0x2c /* ',' */) {
if (start === -1) {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
if (end === -1) end = i;
const protocol = header.slice(start, end);
if (protocols.has(protocol)) {
throw new SyntaxError(`The "${protocol}" subprotocol is duplicated`);
}
protocols.add(protocol);
start = end = -1;
} else {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
}
if (start === -1 || end !== -1) {
throw new SyntaxError('Unexpected end of input');
}
const protocol = header.slice(start, i);
if (protocols.has(protocol)) {
throw new SyntaxError(`The "${protocol}" subprotocol is duplicated`);
}
protocols.add(protocol);
return protocols;
}
module.exports = { parse };