'use strict';
const { tokenChars } = require('./validation');
/**
* Adds an offer to the map of extension offers or a parameter to the map of
* parameters.
*
* @param {Object} dest The map of extension offers or parameters
* @param {String} name The extension or parameter name
* @param {(Object|Boolean|String)} elem The extension parameters or the
* parameter value
* @private
*/
function push(dest, name, elem) {
if (dest[name] === undefined) dest[name] = [elem];
else dest[name].push(elem);
}
/**
* Parses the `Sec-WebSocket-Extensions` header into an object.
*
* @param {String} header The field value of the header
* @return {Object} The parsed object
* @public
*/
function parse(header) {
const offers = Object.create(null);
let params = Object.create(null);
let mustUnescape = false;
let isEscaping = false;
let inQuotes = false;
let extensionName;
let paramName;
let start = -1;
let code = -1;
let end = -1;
let i = 0;
for (; i < header.length; i++) {
code = header.charCodeAt(i);
if (extensionName === undefined) {
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 === 0x3b /* ';' */ || code === 0x2c /* ',' */) {
if (start === -1) {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
if (end === -1) end = i;
const name = header.slice(start, end);
if (code === 0x2c) {
push(offers, name, params);
params = Object.create(null);
} else {
extensionName = name;
}
start = end = -1;
} else {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
} else if (paramName === undefined) {
if (end === -1 && tokenChars[code] === 1) {
if (start === -1) start = i;
} else if (code === 0x20 || code === 0x09) {
if (end === -1 && start !== -1) end = i;
} else if (code === 0x3b || code === 0x2c) {
if (start === -1) {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
if (end === -1) end = i;
push(params, header.slice(start, end), true);
if (code === 0x2c) {
push(offers, extensionName, params);
params = Object.create(null);
extensionName = undefined;
}
start = end = -1;
} else if (code === 0x3d /* '=' */ && start !== -1 && end === -1) {
paramName = header.slice(start, i);
start = end = -1;
} else {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
} else {
//
// The value of a quoted-string after unescaping must conform to the
// token ABNF, so only token characters are valid.
// Ref: https://tools.ietf.org/html/rfc6455#section-9.1
//
if (isEscaping) {
if (tokenChars[code] !== 1) {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
if (start === -1) start = i;
else if (!mustUnescape) mustUnescape = true;
isEscaping = false;
} else if (inQuotes) {
if (tokenChars[code] === 1) {
if (start === -1) start = i;
} else if (code === 0x22 /* '"' */ && start !== -1) {
inQuotes = false;
end = i;
} else if (code === 0x5c /* '\' */) {
isEscaping = true;
} else {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
} else if (code === 0x22 && header.charCodeAt(i - 1) === 0x3d) {
inQuotes = true;
} else if (end === -1 && tokenChars[code] === 1) {
if (start === -1) start = i;
} else if (start !== -1 && (code === 0x20 || code === 0x09)) {
if (end === -1) end = i;
} else if (code === 0x3b || code === 0x2c) {
if (start === -1) {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
if (end === -1) end = i;
let value = header.slice(start, end);
if (mustUnescape) {
value = value.replace(/\\/g, '');
mustUnescape = false;
}
push(params, paramName, value);
if (code === 0x2c) {
push(offers, extensionName, params);
params = Object.create(null);
extensionName = undefined;
}
paramName = undefined;
start = end = -1;
} else {
throw new SyntaxError(`Unexpected character at index ${i}`);
}
}
}
if (start === -1 || inQuotes || code === 0x20 || code === 0x09) {
throw new SyntaxError('Unexpected end of input');
}
if (end === -1) end = i;
const token = header.slice(start, end);
if (extensionName === undefined) {
push(offers, token, params);
} else {
if (paramName === undefined) {
push(params, token, true);
} else if (mustUnescape) {
push(params, paramName, token.replace(/\\/g, ''));
} else {
push(params, paramName, token);
}
push(offers, extensionName, params);
}
return offers;
}
/**
* Builds the `Sec-WebSocket-Extensions` header field value.
*
* @param {Object} extensions The map of extensions and parameters to format
* @return {String} A string representing the given object
* @public
*/
function format(extensions) {
return Object.keys(extensions)
.map((extension) => {
let configurations = extensions[extension];
if (!Array.isArray(configurations)) configurations = [configurations];
return configurations
.map((params) => {
return [extension]
.concat(
Object.keys(params).map((k) => {
let values = params[k];
if (!Array.isArray(values)) values = [values];
return values
.map((v) => (v === true ? k : `${k}=${v}`))
.join('; ');
})
)
.join('; ');
})
.join(', ');
})
.join(', ');
}
module.exports = { format, parse };