'use strict'
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var Buffer = require('safe-buffer').Buffer
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/* Protocol - protocol constants */
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var protocol = module.exports
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/* Command code => mnemonic */
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protocol.types = {
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0: 'reserved',
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1: 'connect',
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2: 'connack',
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3: 'publish',
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4: 'puback',
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5: 'pubrec',
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6: 'pubrel',
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7: 'pubcomp',
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8: 'subscribe',
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9: 'suback',
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10: 'unsubscribe',
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11: 'unsuback',
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12: 'pingreq',
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13: 'pingresp',
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14: 'disconnect',
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15: 'reserved'
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}
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/* Mnemonic => Command code */
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protocol.codes = {}
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for (var k in protocol.types) {
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var v = protocol.types[k]
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protocol.codes[v] = k
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}
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/* Header */
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protocol.CMD_SHIFT = 4
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protocol.CMD_MASK = 0xF0
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protocol.DUP_MASK = 0x08
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protocol.QOS_MASK = 0x03
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protocol.QOS_SHIFT = 1
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protocol.RETAIN_MASK = 0x01
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/* Length */
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protocol.LENGTH_MASK = 0x7F
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protocol.LENGTH_FIN_MASK = 0x80
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/* Connack */
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protocol.SESSIONPRESENT_MASK = 0x01
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protocol.SESSIONPRESENT_HEADER = Buffer.from([protocol.SESSIONPRESENT_MASK])
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protocol.CONNACK_HEADER = Buffer.from([protocol.codes['connack'] << protocol.CMD_SHIFT])
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/* Connect */
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protocol.USERNAME_MASK = 0x80
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protocol.PASSWORD_MASK = 0x40
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protocol.WILL_RETAIN_MASK = 0x20
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protocol.WILL_QOS_MASK = 0x18
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protocol.WILL_QOS_SHIFT = 3
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protocol.WILL_FLAG_MASK = 0x04
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protocol.CLEAN_SESSION_MASK = 0x02
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protocol.CONNECT_HEADER = Buffer.from([protocol.codes['connect'] << protocol.CMD_SHIFT])
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function genHeader (type) {
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return [0, 1, 2].map(function (qos) {
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return [0, 1].map(function (dup) {
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return [0, 1].map(function (retain) {
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var buf = new Buffer(1)
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buf.writeUInt8(
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protocol.codes[type] << protocol.CMD_SHIFT |
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(dup ? protocol.DUP_MASK : 0) |
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qos << protocol.QOS_SHIFT | retain, 0, true)
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return buf
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})
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})
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})
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}
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/* Publish */
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protocol.PUBLISH_HEADER = genHeader('publish')
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/* Subscribe */
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protocol.SUBSCRIBE_HEADER = genHeader('subscribe')
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/* Unsubscribe */
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protocol.UNSUBSCRIBE_HEADER = genHeader('unsubscribe')
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/* Confirmations */
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protocol.ACKS = {
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unsuback: genHeader('unsuback'),
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puback: genHeader('puback'),
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pubcomp: genHeader('pubcomp'),
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pubrel: genHeader('pubrel'),
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pubrec: genHeader('pubrec')
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}
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protocol.SUBACK_HEADER = Buffer.from([protocol.codes['suback'] << protocol.CMD_SHIFT])
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/* Protocol versions */
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protocol.VERSION3 = Buffer.from([3])
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protocol.VERSION4 = Buffer.from([4])
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/* QoS */
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protocol.QOS = [0, 1, 2].map(function (qos) {
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return Buffer.from([qos])
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})
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/* Empty packets */
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protocol.EMPTY = {
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pingreq: Buffer.from([protocol.codes['pingreq'] << 4, 0]),
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pingresp: Buffer.from([protocol.codes['pingresp'] << 4, 0]),
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disconnect: Buffer.from([protocol.codes['disconnect'] << 4, 0])
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}
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