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parse.js
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parse.js
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/* Parse - packet parsing */
var protocol = require('./protocol');
module.exports.header = function(buf, packet) {
packet.cmd = protocol.types[buf[0] >> protocol.CMD_SHIFT];
packet.retain = (buf[0] & protocol.RETAIN_MASK) !== 0;
packet.qos = (buf[0] >> protocol.QOS_SHIFT) & protocol.QOS_MASK;
packet.dup = (buf[0] & protocol.DUP_MASK) !== 0;
return packet;
};
module.exports.connect = function(buf, packet) {
var pos = 0
, len = buf.length
, flags = {};
/* Parse version string */
version_and_len = parse_string(buf, len, pos);
packet.version = version_and_len[0];
if(packet.version === null) return null;
pos += version_and_len[1] + 2;
/* Parse version number */
if(pos > len) return null;
packet.versionNum = buf[pos];
pos += 1;
/* Parse connect flags */
flags.username = (buf[pos] & protocol.USERNAME_MASK);
flags.password = (buf[pos] & protocol.PASSWORD_MASK);
flags.will = (buf[pos] & protocol.WILL_FLAG_MASK);
if(flags.will) {
packet.will = {}
packet.will.retain = (buf[pos] & protocol.WILL_RETAIN_MASK) !== 0;
packet.will.qos = (buf[pos] & protocol.WILL_QOS_MASK) >> protocol.WILL_QOS_SHIFT;
}
packet.clean = (buf[pos] & protocol.CLEAN_SESSION_MASK) !== 0;
pos += 1;
/* Parse keepalive */
packet.keepalive = parse_num(buf, len, pos);
if(packet.keepalive === null) return null;
pos += 2;
/* Parse client ID */
client_and_len = parse_string(buf, len, pos);
packet.client = client_and_len[0];
if(packet.client === null) return null;
pos += client_and_len[1] + 2;
if(flags.will) {
/* Parse will topic */
topic_and_len = parse_string(buf, len, pos);
packet.will.topic = topic_and_len[0];
if(packet.will.topic === null) return null;
pos += topic_and_len[1] + 2;
/* Parse will payload */
payload_and_len = parse_string(buf, len, pos);
packet.will.payload = payload_and_len[0];
if(packet.will.payload === null) return null;
pos += payload_and_len[1] + 2;
}
/* Parse username */
if(flags.username) {
username_and_len = parse_string(buf, len, pos);
packet.username = username_and_len[0];
if(packet.username === null) return null;
pos += username_and_len[1] + 2;
}
/* Parse password */
if(flags.password) {
password_and_len = parse_string(buf, len, pos);
packet.password = password_and_len[0];
if(packet.password === null) return null;
pos += password_and_len[1] + 2;
}
return packet;
};
module.exports.connack = function(buf, packet) {
var len = buf.length
, pos = 0;
packet.returnCode = parse_num(buf, len, pos);
if(packet.returnCode === null) return null;
return packet;
};
module.exports.publish = function(buf, packet) {
var len = buf.length
, pos = 0;
/* Parse topic name */
topic_and_len = parse_string(buf, len, pos);
packet.topic = topic_and_len[0];
if(packet.topic === null) return null;
pos += topic_and_len[1] + 2;
/* Parse message ID */
if (packet.qos > 0) {
packet.messageId = parse_num(buf, len, pos);
if(packet.messageId === null) return null;
pos += 2;
}
/* Parse the payload */
/* No checks - whatever remains in the packet is the payload */
packet.payload = buf.toString('utf8', pos, len);
return packet;
}
var pubs = ['puback', 'pubrec', 'pubrel', 'pubcomp', 'unsuback'];
for (var i = 0; i < pubs.length; i++) {
module.exports[pubs[i]] = function(buf, packet) {
var len = buf.length
, pos = 0;
packet.messageId = parse_num(buf, len, pos);
if (packet.messageId === null) return null;
return packet;
};
}
module.exports.subscribe = function(buf, packet) {
var len = buf.length
, pos = 0;
packet.subscriptions = [];
/* Parse message ID */
packet.messageId = parse_num(buf, len, pos);
if(packet.messageId === null) return null;
pos += 2;
while(pos < len) {
var topic, qos;
/* Parse topic */
topic_and_len = parse_string(buf, len, pos);
topic = topic_and_len[0];
if(topic === null) return null;
pos += topic_and_len[1] + 2;
/* Parse QoS */
qos = buf[pos++];
/* Push pair to subscriptions */
packet.subscriptions.push({topic: topic, qos: qos});
}
return packet;
};
module.exports.suback = function(buf, packet) {
var len = buf.length
, pos = 0;
packet.granted = [];
/* Parse message ID */
packet.messageId = parse_num(buf, len, pos);
if(packet.messageId === null) return null;
pos += 2;
while(pos < len) {
packet.granted.push(buf[pos++]);
}
return packet;
};
module.exports.unsubscribe = function(buf, packet) {
var len = buf.length
, pos = 0;
packet.unsubscriptions = [];
/* Parse message ID */
packet.messageId = parse_num(buf, len, pos);
if(packet.messageId === null) return null;
pos += 2;
while(pos < len) {
var topic;
/* Parse topic */
topic_and_len = parse_string(buf, len, pos);
topic = topic_and_len[0];
if(topic === null) return null;
pos += topic_and_len[1] + 2;
/* Push topic to unsubscriptions */
packet.unsubscriptions.push(topic);
}
return packet;
};
var empties = ['pingreq', 'pingresp', 'disconnect'];
for (var i = 0; i < empties.length; i++) {
module.exports[empties[i]] = function(buf, packet) {
return {};
};
}
var parse_num = function(buf, len, pos) {
if(2 > pos + len) return null;
return buf.readUInt16BE(pos);
}
var parse_string = function(buf, len, pos) {
var length = parse_num(buf, len, pos);
if(length === null || length > pos + len) return null;
return [buf.toString('utf8', pos + 2, pos + length + 2), length];
}