"use strict";
const protocol = require('./protocol');
const crypto = require('crypto');
/* TODO: consider rewriting these functions using buffers instead
* of arrays
*/
/** Publish
* @memberof MqttConnector
*/
module.exports.publish = function(opts) {
opts = opts || {};
let dup = opts.dup ? protocol.DUP_MASK : 0;
let qos = opts.qos || 0;
let retain = opts.retain ? protocol.RETAIN_MASK : 0;
let topic = opts.topic;
let payload = opts.payload || Buffer.allocUnsafe(0);
let id = (typeof opts.messageId === 'undefined') ? randint() : opts.messageId;
let packet = {header: 0, payload: []};
/* Check required fields */
if (typeof topic !== 'string' || topic.length <= 0) return null;
/* if payload is a string, we'll convert it into a buffer */
if(typeof payload == 'string') {
payload = Buffer.from(payload);
}
/* accepting only a buffer for payload */
if (!Buffer.isBuffer(payload)) return null;
if (typeof qos !== 'number' || qos < 0 || qos > 2) return null;
if (typeof id !== 'number' || id < 0 || id > 0xFFFF) return null;
/* Generate header */
packet.header = protocol.codes.publish << protocol.CMD_SHIFT | dup | qos << protocol.QOS_SHIFT | retain;
/* Topic name */
packet.payload = packet.payload.concat(gen_string(topic));
/* Message ID */
if (qos > 0) packet.payload = packet.payload.concat(gen_number(id));
let buf = Buffer.from([packet.header]
.concat(gen_length(packet.payload.length + payload.length))
.concat(packet.payload));
return Buffer.concat([buf, payload]);
};
/* Requires length be a number > 0 */
let gen_length = function(length) {
if(typeof length !== "number") return null;
if(length < 0) return null;
let len = [];
let digit = 0;
do {
digit = length % 128 | 0;
length = length / 128 | 0;
if (length > 0) {
digit = digit | 0x80;
}
len.push(digit);
} while (length > 0);
return len;
};
let gen_string = function(str, without_length) { /* based on code in (from http://farhadi.ir/downloads/utf8.js) */
if(arguments.length < 2) without_length = false;
if(typeof str !== "string") return null;
if(typeof without_length !== "boolean") return null;
let string = [];
let length = 0;
for(let i = 0; i < str.length; i++) {
let code = str.charCodeAt(i);
if (code < 128) {
string.push(code); ++length;
} else if (code < 2048) {
string.push(192 + ((code >> 6 ) )); ++length;
string.push(128 + ((code ) & 63)); ++length;
} else if (code < 65536) {
string.push(224 + ((code >> 12) )); ++length;
string.push(128 + ((code >> 6 ) & 63)); ++length;
string.push(128 + ((code ) & 63)); ++length;
} else if (code < 2097152) {
string.push(240 + ((code >> 18) )); ++length;
string.push(128 + ((code >> 12) & 63)); ++length;
string.push(128 + ((code >> 6 ) & 63)); ++length;
string.push(128 + ((code ) & 63)); ++length;
} else {
throw new Error("Can't encode character with code " + code);
}
}
return without_length ? string : gen_number(length).concat(string);
};
let gen_number = function(num) {
let number = [num >> 8, num & 0x00FF];
return number;
};
let randint = function() { return Math.floor(Math.random() * 0xFFFF); };