code:
'use strict'

const Buffer = require('buffer').Buffer
const types = require('./types')
const rcodes = require('./rcodes')
const opcodes = require('./opcodes')
const classes = require('./classes')
const optioncodes = require('./optioncodes')
const ip = require('@leichtgewicht/ip-codec')

const QUERY_FLAG = 0
const RESPONSE_FLAG = 1 << 15
const FLUSH_MASK = 1 << 15
const NOT_FLUSH_MASK = ~FLUSH_MASK
const QU_MASK = 1 << 15
const NOT_QU_MASK = ~QU_MASK

const name = exports.name = {}

name.encode = function (str, buf, offset, { mail = false } = {}) {
  if (!buf) buf = Buffer.alloc(name.encodingLength(str))
  if (!offset) offset = 0
  const oldOffset = offset

  // strip leading and trailing .
  const n = str.replace(/^\.|\.$/gm, '')
  if (n.length) {
    let list = []
    if (mail) {
      let localPart = ''
      n.split('.').forEach(label => {
        if (label.endsWith('\\')) {
          localPart += (localPart.length ? '.' : '') + label.slice(0, -1)
        } else {
          if (list.length === 0 && localPart.length) {
            list.push(localPart + '.' + label)
          } else {
            list.push(label)
          }
        }
      })
    } else {
      list = n.split('.')
    }

    for (let i = 0; i < list.length; i++) {
      const len = buf.write(list[i], offset + 1)
      buf[offset] = len
      offset += len + 1
    }
  }

  buf[offset++] = 0

  name.encode.bytes = offset - oldOffset
  return buf
}

name.encode.bytes = 0

name.decode = function (buf, offset, { mail = false } = {}) {
  if (!offset) offset = 0

  const list = []
  let oldOffset = offset
  let totalLength = 0
  let consumedBytes = 0
  let jumped = false

  while (true) {
    if (offset >= buf.length) {
      throw new Error('Cannot decode name (buffer overflow)')
    }
    const len = buf[offset++]
    consumedBytes += jumped ? 0 : 1

    if (len === 0) {
      break
    } else if ((len & 0xc0) === 0) {
      if (offset + len > buf.length) {
        throw new Error('Cannot decode name (buffer overflow)')
      }
      totalLength += len + 1
      if (totalLength > 254) {
        throw new Error('Cannot decode name (name too long)')
      }
      let label = buf.toString('utf-8', offset, offset + len)
      if (mail) {
        label = label.replace(/\./g, '\\.')
      }
      list.push(label)
      offset += len
      consumedBytes += jumped ? 0 : len
    } else if ((len & 0xc0) === 0xc0) {
      if (offset + 1 > buf.length) {
        throw new Error('Cannot decode name (buffer overflow)')
      }
      const jumpOffset = buf.readUInt16BE(offset - 1) - 0xc000
      if (jumpOffset >= oldOffset) {
        // Allow only pointers to prior data. RFC 1035, section 4.1.4 states:
        // "[...] an entire domain name or a list of labels at the end of a domain name
        // is replaced with a pointer to a prior occurance (sic) of the same name."
        throw new Error('Cannot decode name (bad pointer)')
      }
      offset = jumpOffset
      oldOffset = jumpOffset
      consumedBytes += jumped ? 0 : 1
      jumped = true
    } else {
      throw new Error('Cannot decode name (bad label)')
    }
  }

  name.decode.bytes = consumedBytes
  return list.length === 0 ? '.' : list.join('.')
}

name.decode.bytes = 0

name.encodingLength = function (n) {
  if (n === '.' || n === '..') return 1
  return Buffer.byteLength(n.replace(/^\.|\.$/gm, '')) + 2
}

const string = {}

string.encode = function (s, buf, offset) {
  if (!buf) buf = Buffer.alloc(string.encodingLength(s))
  if (!offset) offset = 0

  const len = buf.write(s, offset + 1)
  buf[offset] = len
  string.encode.bytes = len + 1
  return buf
}

string.encode.bytes = 0

string.decode = function (buf, offset) {
  if (!offset) offset = 0

  const len = buf[offset]
  const s = buf.toString('utf-8', offset + 1, offset + 1 + len)
  string.decode.bytes = len + 1
  return s
}

string.decode.bytes = 0

string.encodingLength = function (s) {
  return Buffer.byteLength(s) + 1
}

const header = {}

header.encode = function (h, buf, offset) {
  if (!buf) buf = header.encodingLength(h)
  if (!offset) offset = 0

  const flags = (h.flags || 0) & 32767
  const type = h.type === 'response' ? RESPONSE_FLAG : QUERY_FLAG

  buf.writeUInt16BE(h.id || 0, offset)
  buf.writeUInt16BE(flags | type, offset + 2)
  buf.writeUInt16BE(h.questions.length, offset + 4)
  buf.writeUInt16BE(h.answers.length, offset + 6)
  buf.writeUInt16BE(h.authorities.length, offset + 8)
  buf.writeUInt16BE(h.additionals.length, offset + 10)

  return buf
}

header.encode.bytes = 12

header.decode = function (buf, offset) {
  if (!offset) offset = 0
  if (buf.length < 12) throw new Error('Header must be 12 bytes')
  const flags = buf.readUInt16BE(offset + 2)

  return {
    id: buf.readUInt16BE(offset),
    type: flags & RESPONSE_FLAG ? 'response' : 'query',
    flags: flags & 32767,
    flag_qr: ((flags >> 15) & 0x1) === 1,
    opcode: opcodes.toString((flags >> 11) & 0xf),
    flag_aa: ((flags >> 10) & 0x1) === 1,
    flag_tc: ((flags >> 9) & 0x1) === 1,
    flag_rd: ((flags >> 8) & 0x1) === 1,
    flag_ra: ((flags >> 7) & 0x1) === 1,
    flag_z: ((flags >> 6) & 0x1) === 1,
    flag_ad: ((flags >> 5) & 0x1) === 1,
    flag_cd: ((flags >> 4) & 0x1) === 1,
    rcode: rcodes.toString(flags & 0xf),
    questions: new Array(buf.readUInt16BE(offset + 4)),
    answers: new Array(buf.readUInt16BE(offset + 6)),
    authorities: new Array(buf.readUInt16BE(offset + 8)),
    additionals: new Array(buf.readUInt16BE(offset + 10))
  }
}

header.decode.bytes = 12

header.encodingLength = function () {
  return 12
}

const runknown = exports.unknown = {}

runknown.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(runknown.encodingLength(data))
  if (!offset) offset = 0

  buf.writeUInt16BE(data.length, offset)
  data.copy(buf, offset + 2)

  runknown.encode.bytes = data.length + 2
  return buf
}

runknown.encode.bytes = 0

runknown.decode = function (buf, offset) {
  if (!offset) offset = 0

  const len = buf.readUInt16BE(offset)
  const data = buf.slice(offset + 2, offset + 2 + len)
  runknown.decode.bytes = len + 2
  return data
}

runknown.decode.bytes = 0

runknown.encodingLength = function (data) {
  return data.length + 2
}

const rns = exports.ns = {}

rns.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(rns.encodingLength(data))
  if (!offset) offset = 0

  name.encode(data, buf, offset + 2)
  buf.writeUInt16BE(name.encode.bytes, offset)
  rns.encode.bytes = name.encode.bytes + 2
  return buf
}

rns.encode.bytes = 0

rns.decode = function (buf, offset) {
  if (!offset) offset = 0

  const len = buf.readUInt16BE(offset)
  const dd = name.decode(buf, offset + 2)

  rns.decode.bytes = len + 2
  return dd
}

rns.decode.bytes = 0

rns.encodingLength = function (data) {
  return name.encodingLength(data) + 2
}

const rsoa = exports.soa = {}

rsoa.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(rsoa.encodingLength(data))
  if (!offset) offset = 0

  const oldOffset = offset
  offset += 2
  name.encode(data.mname, buf, offset)
  offset += name.encode.bytes
  name.encode(data.rname, buf, offset, { mail: true })
  offset += name.encode.bytes
  buf.writeUInt32BE(data.serial || 0, offset)
  offset += 4
  buf.writeUInt32BE(data.refresh || 0, offset)
  offset += 4
  buf.writeUInt32BE(data.retry || 0, offset)
  offset += 4
  buf.writeUInt32BE(data.expire || 0, offset)
  offset += 4
  buf.writeUInt32BE(data.minimum || 0, offset)
  offset += 4

  buf.writeUInt16BE(offset - oldOffset - 2, oldOffset)
  rsoa.encode.bytes = offset - oldOffset
  return buf
}

rsoa.encode.bytes = 0

rsoa.decode = function (buf, offset) {
  if (!offset) offset = 0

  const oldOffset = offset

  const data = {}
  offset += 2
  data.mname = name.decode(buf, offset)
  offset += name.decode.bytes
  data.rname = name.decode(buf, offset, { mail: true })
  offset += name.decode.bytes
  data.serial = buf.readUInt32BE(offset)
  offset += 4
  data.refresh = buf.readUInt32BE(offset)
  offset += 4
  data.retry = buf.readUInt32BE(offset)
  offset += 4
  data.expire = buf.readUInt32BE(offset)
  offset += 4
  data.minimum = buf.readUInt32BE(offset)
  offset += 4

  rsoa.decode.bytes = offset - oldOffset
  return data
}

rsoa.decode.bytes = 0

rsoa.encodingLength = function (data) {
  return 22 + name.encodingLength(data.mname) + name.encodingLength(data.rname)
}

const rtxt = exports.txt = {}

rtxt.encode = function (data, buf, offset) {
  if (!Array.isArray(data)) data = [data]
  for (let i = 0; i < data.length; i++) {
    if (typeof data[i] === 'string') {
      data[i] = Buffer.from(data[i])
    }
    if (!Buffer.isBuffer(data[i])) {
      throw new Error('Must be a Buffer')
    }
  }

  if (!buf) buf = Buffer.alloc(rtxt.encodingLength(data))
  if (!offset) offset = 0

  const oldOffset = offset
  offset += 2

  data.forEach(function (d) {
    buf[offset++] = d.length
    d.copy(buf, offset, 0, d.length)
    offset += d.length
  })

  buf.writeUInt16BE(offset - oldOffset - 2, oldOffset)
  rtxt.encode.bytes = offset - oldOffset
  return buf
}

rtxt.encode.bytes = 0

rtxt.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset
  let remaining = buf.readUInt16BE(offset)
  offset += 2

  let data = []
  while (remaining > 0) {
    const len = buf[offset++]
    --remaining
    if (remaining < len) {
      throw new Error('Buffer overflow')
    }
    data.push(buf.slice(offset, offset + len))
    offset += len
    remaining -= len
  }

  rtxt.decode.bytes = offset - oldOffset
  return data
}

rtxt.decode.bytes = 0

rtxt.encodingLength = function (data) {
  if (!Array.isArray(data)) data = [data]
  let length = 2
  data.forEach(function (buf) {
    if (typeof buf === 'string') {
      length += Buffer.byteLength(buf) + 1
    } else {
      length += buf.length + 1
    }
  })
  return length
}

const rnull = exports.null = {}

rnull.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(rnull.encodingLength(data))
  if (!offset) offset = 0

  if (typeof data === 'string') data = Buffer.from(data)
  if (!data) data = Buffer.alloc(0)

  const oldOffset = offset
  offset += 2

  const len = data.length
  data.copy(buf, offset, 0, len)
  offset += len

  buf.writeUInt16BE(offset - oldOffset - 2, oldOffset)
  rnull.encode.bytes = offset - oldOffset
  return buf
}

rnull.encode.bytes = 0

rnull.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset
  const len = buf.readUInt16BE(offset)

  offset += 2

  const data = buf.slice(offset, offset + len)
  offset += len

  rnull.decode.bytes = offset - oldOffset
  return data
}

rnull.decode.bytes = 0

rnull.encodingLength = function (data) {
  if (!data) return 2
  return (Buffer.isBuffer(data) ? data.length : Buffer.byteLength(data)) + 2
}

const rhinfo = exports.hinfo = {}

rhinfo.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(rhinfo.encodingLength(data))
  if (!offset) offset = 0

  const oldOffset = offset
  offset += 2
  string.encode(data.cpu, buf, offset)
  offset += string.encode.bytes
  string.encode(data.os, buf, offset)
  offset += string.encode.bytes
  buf.writeUInt16BE(offset - oldOffset - 2, oldOffset)
  rhinfo.encode.bytes = offset - oldOffset
  return buf
}

rhinfo.encode.bytes = 0

rhinfo.decode = function (buf, offset) {
  if (!offset) offset = 0

  const oldOffset = offset

  const data = {}
  offset += 2
  data.cpu = string.decode(buf, offset)
  offset += string.decode.bytes
  data.os = string.decode(buf, offset)
  offset += string.decode.bytes
  rhinfo.decode.bytes = offset - oldOffset
  return data
}

rhinfo.decode.bytes = 0

rhinfo.encodingLength = function (data) {
  return string.encodingLength(data.cpu) + string.encodingLength(data.os) + 2
}

const rptr = exports.ptr = {}
const rcname = exports.cname = rptr
const rdname = exports.dname = rptr

rptr.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(rptr.encodingLength(data))
  if (!offset) offset = 0

  name.encode(data, buf, offset + 2)
  buf.writeUInt16BE(name.encode.bytes, offset)
  rptr.encode.bytes = name.encode.bytes + 2
  return buf
}

rptr.encode.bytes = 0

rptr.decode = function (buf, offset) {
  if (!offset) offset = 0

  const data = name.decode(buf, offset + 2)
  rptr.decode.bytes = name.decode.bytes + 2
  return data
}

rptr.decode.bytes = 0

rptr.encodingLength = function (data) {
  return name.encodingLength(data) + 2
}

const rsrv = exports.srv = {}

rsrv.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(rsrv.encodingLength(data))
  if (!offset) offset = 0

  buf.writeUInt16BE(data.priority || 0, offset + 2)
  buf.writeUInt16BE(data.weight || 0, offset + 4)
  buf.writeUInt16BE(data.port || 0, offset + 6)
  name.encode(data.target, buf, offset + 8)

  const len = name.encode.bytes + 6
  buf.writeUInt16BE(len, offset)

  rsrv.encode.bytes = len + 2
  return buf
}

rsrv.encode.bytes = 0

rsrv.decode = function (buf, offset) {
  if (!offset) offset = 0

  const len = buf.readUInt16BE(offset)

  const data = {}
  data.priority = buf.readUInt16BE(offset + 2)
  data.weight = buf.readUInt16BE(offset + 4)
  data.port = buf.readUInt16BE(offset + 6)
  data.target = name.decode(buf, offset + 8)

  rsrv.decode.bytes = len + 2
  return data
}

rsrv.decode.bytes = 0

rsrv.encodingLength = function (data) {
  return 8 + name.encodingLength(data.target)
}

const rcaa = exports.caa = {}

rcaa.ISSUER_CRITICAL = 1 << 7

rcaa.encode = function (data, buf, offset) {
  const len = rcaa.encodingLength(data)

  if (!buf) buf = Buffer.alloc(rcaa.encodingLength(data))
  if (!offset) offset = 0

  if (data.issuerCritical) {
    data.flags = rcaa.ISSUER_CRITICAL
  }

  buf.writeUInt16BE(len - 2, offset)
  offset += 2
  buf.writeUInt8(data.flags || 0, offset)
  offset += 1
  string.encode(data.tag, buf, offset)
  offset += string.encode.bytes
  buf.write(data.value, offset)
  offset += Buffer.byteLength(data.value)

  rcaa.encode.bytes = len
  return buf
}

rcaa.encode.bytes = 0

rcaa.decode = function (buf, offset) {
  if (!offset) offset = 0

  const len = buf.readUInt16BE(offset)
  offset += 2

  const oldOffset = offset
  const data = {}
  data.flags = buf.readUInt8(offset)
  offset += 1
  data.tag = string.decode(buf, offset)
  offset += string.decode.bytes
  data.value = buf.toString('utf-8', offset, oldOffset + len)

  data.issuerCritical = !!(data.flags & rcaa.ISSUER_CRITICAL)

  rcaa.decode.bytes = len + 2

  return data
}

rcaa.decode.bytes = 0

rcaa.encodingLength = function (data) {
  return string.encodingLength(data.tag) + string.encodingLength(data.value) + 2
}

const rmx = exports.mx = {}

rmx.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(rmx.encodingLength(data))
  if (!offset) offset = 0

  const oldOffset = offset
  offset += 2
  buf.writeUInt16BE(data.preference || 0, offset)
  offset += 2
  name.encode(data.exchange, buf, offset)
  offset += name.encode.bytes

  buf.writeUInt16BE(offset - oldOffset - 2, oldOffset)
  rmx.encode.bytes = offset - oldOffset
  return buf
}

rmx.encode.bytes = 0

rmx.decode = function (buf, offset) {
  if (!offset) offset = 0

  const oldOffset = offset

  const data = {}
  offset += 2
  data.preference = buf.readUInt16BE(offset)
  offset += 2
  data.exchange = name.decode(buf, offset)
  offset += name.decode.bytes

  rmx.decode.bytes = offset - oldOffset
  return data
}

rmx.encodingLength = function (data) {
  return 4 + name.encodingLength(data.exchange)
}

const ra = exports.a = {}

ra.encode = function (host, buf, offset) {
  if (!buf) buf = Buffer.alloc(ra.encodingLength(host))
  if (!offset) offset = 0

  buf.writeUInt16BE(4, offset)
  offset += 2
  ip.v4.encode(host, buf, offset)
  ra.encode.bytes = 6
  return buf
}

ra.encode.bytes = 0

ra.decode = function (buf, offset) {
  if (!offset) offset = 0

  offset += 2
  const host = ip.v4.decode(buf, offset)
  ra.decode.bytes = 6
  return host
}

ra.decode.bytes = 0

ra.encodingLength = function () {
  return 6
}

const raaaa = exports.aaaa = {}

raaaa.encode = function (host, buf, offset) {
  if (!buf) buf = Buffer.alloc(raaaa.encodingLength(host))
  if (!offset) offset = 0

  buf.writeUInt16BE(16, offset)
  offset += 2
  ip.v6.encode(host, buf, offset)
  raaaa.encode.bytes = 18
  return buf
}

raaaa.encode.bytes = 0

raaaa.decode = function (buf, offset) {
  if (!offset) offset = 0

  offset += 2
  const host = ip.v6.decode(buf, offset)
  raaaa.decode.bytes = 18
  return host
}

raaaa.decode.bytes = 0

raaaa.encodingLength = function () {
  return 18
}

const roption = exports.option = {}

roption.encode = function (option, buf, offset) {
  if (!buf) buf = Buffer.alloc(roption.encodingLength(option))
  if (!offset) offset = 0
  const oldOffset = offset

  const code = optioncodes.toCode(option.code)
  buf.writeUInt16BE(code, offset)
  offset += 2
  if (option.data) {
    buf.writeUInt16BE(option.data.length, offset)
    offset += 2
    option.data.copy(buf, offset)
    offset += option.data.length
  } else {
    switch (code) {
      // case 3: NSID.  No encode makes sense.
      // case 5,6,7: Not implementable
      case 8: // ECS
        // note: do IP math before calling
        const spl = option.sourcePrefixLength || 0
        const fam = option.family || ip.familyOf(option.ip)
        const ipBuf = ip.encode(option.ip, Buffer.alloc)
        const ipLen = Math.ceil(spl / 8)
        buf.writeUInt16BE(ipLen + 4, offset)
        offset += 2
        buf.writeUInt16BE(fam, offset)
        offset += 2
        buf.writeUInt8(spl, offset++)
        buf.writeUInt8(option.scopePrefixLength || 0, offset++)

        ipBuf.copy(buf, offset, 0, ipLen)
        offset += ipLen
        break
      // case 9: EXPIRE (experimental)
      // case 10: COOKIE.  No encode makes sense.
      case 11: // KEEP-ALIVE
        if (option.timeout) {
          buf.writeUInt16BE(2, offset)
          offset += 2
          buf.writeUInt16BE(option.timeout, offset)
          offset += 2
        } else {
          buf.writeUInt16BE(0, offset)
          offset += 2
        }
        break
      case 12: // PADDING
        const len = option.length || 0
        buf.writeUInt16BE(len, offset)
        offset += 2
        buf.fill(0, offset, offset + len)
        offset += len
        break
      // case 13:  CHAIN.  Experimental.
      case 14: // KEY-TAG
        const tagsLen = option.tags.length * 2
        buf.writeUInt16BE(tagsLen, offset)
        offset += 2
        for (const tag of option.tags) {
          buf.writeUInt16BE(tag, offset)
          offset += 2
        }
        break
      default:
        throw new Error(`Unknown roption code: ${option.code}`)
    }
  }

  roption.encode.bytes = offset - oldOffset
  return buf
}

roption.encode.bytes = 0

roption.decode = function (buf, offset) {
  if (!offset) offset = 0
  const option = {}
  option.code = buf.readUInt16BE(offset)
  option.type = optioncodes.toString(option.code)
  offset += 2
  const len = buf.readUInt16BE(offset)
  offset += 2
  option.data = buf.slice(offset, offset + len)
  switch (option.code) {
    // case 3: NSID.  No decode makes sense.
    case 8: // ECS
      option.family = buf.readUInt16BE(offset)
      offset += 2
      option.sourcePrefixLength = buf.readUInt8(offset++)
      option.scopePrefixLength = buf.readUInt8(offset++)
      const padded = Buffer.alloc((option.family === 1) ? 4 : 16)
      buf.copy(padded, 0, offset, offset + len - 4)
      option.ip = ip.decode(padded)
      break
    // case 12: Padding.  No decode makes sense.
    case 11: // KEEP-ALIVE
      if (len > 0) {
        option.timeout = buf.readUInt16BE(offset)
        offset += 2
      }
      break
    case 14:
      option.tags = []
      for (let i = 0; i < len; i += 2) {
        option.tags.push(buf.readUInt16BE(offset))
        offset += 2
      }
    // don't worry about default.  caller will use data if desired
  }

  roption.decode.bytes = len + 4
  return option
}

roption.decode.bytes = 0

roption.encodingLength = function (option) {
  if (option.data) {
    return option.data.length + 4
  }
  const code = optioncodes.toCode(option.code)
  switch (code) {
    case 8: // ECS
      const spl = option.sourcePrefixLength || 0
      return Math.ceil(spl / 8) + 8
    case 11: // KEEP-ALIVE
      return (typeof option.timeout === 'number') ? 6 : 4
    case 12: // PADDING
      return option.length + 4
    case 14: // KEY-TAG
      return 4 + (option.tags.length * 2)
  }
  throw new Error(`Unknown roption code: ${option.code}`)
}

const ropt = exports.opt = {}

ropt.encode = function (options, buf, offset) {
  if (!buf) buf = Buffer.alloc(ropt.encodingLength(options))
  if (!offset) offset = 0
  const oldOffset = offset

  const rdlen = encodingLengthList(options, roption)
  buf.writeUInt16BE(rdlen, offset)
  offset = encodeList(options, roption, buf, offset + 2)

  ropt.encode.bytes = offset - oldOffset
  return buf
}

ropt.encode.bytes = 0

ropt.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset

  const options = []
  let rdlen = buf.readUInt16BE(offset)
  offset += 2
  let o = 0
  while (rdlen > 0) {
    options[o++] = roption.decode(buf, offset)
    offset += roption.decode.bytes
    rdlen -= roption.decode.bytes
  }
  ropt.decode.bytes = offset - oldOffset
  return options
}

ropt.decode.bytes = 0

ropt.encodingLength = function (options) {
  return 2 + encodingLengthList(options || [], roption)
}

const rdnskey = exports.dnskey = {}

rdnskey.PROTOCOL_DNSSEC = 3
rdnskey.ZONE_KEY = 0x80
rdnskey.SECURE_ENTRYPOINT = 0x8000

rdnskey.encode = function (key, buf, offset) {
  if (!buf) buf = Buffer.alloc(rdnskey.encodingLength(key))
  if (!offset) offset = 0
  const oldOffset = offset

  const keydata = key.key
  if (!Buffer.isBuffer(keydata)) {
    throw new Error('Key must be a Buffer')
  }

  offset += 2 // Leave space for length
  buf.writeUInt16BE(key.flags, offset)
  offset += 2
  buf.writeUInt8(rdnskey.PROTOCOL_DNSSEC, offset)
  offset += 1
  buf.writeUInt8(key.algorithm, offset)
  offset += 1
  keydata.copy(buf, offset, 0, keydata.length)
  offset += keydata.length

  rdnskey.encode.bytes = offset - oldOffset
  buf.writeUInt16BE(rdnskey.encode.bytes - 2, oldOffset)
  return buf
}

rdnskey.encode.bytes = 0

rdnskey.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset

  var key = {}
  var length = buf.readUInt16BE(offset)
  offset += 2
  key.flags = buf.readUInt16BE(offset)
  offset += 2
  if (buf.readUInt8(offset) !== rdnskey.PROTOCOL_DNSSEC) {
    throw new Error('Protocol must be 3')
  }
  offset += 1
  key.algorithm = buf.readUInt8(offset)
  offset += 1
  key.key = buf.slice(offset, oldOffset + length + 2)
  offset += key.key.length
  rdnskey.decode.bytes = offset - oldOffset
  return key
}

rdnskey.decode.bytes = 0

rdnskey.encodingLength = function (key) {
  return 6 + Buffer.byteLength(key.key)
}

const rrrsig = exports.rrsig = {}

rrrsig.encode = function (sig, buf, offset) {
  if (!buf) buf = Buffer.alloc(rrrsig.encodingLength(sig))
  if (!offset) offset = 0
  const oldOffset = offset

  const signature = sig.signature
  if (!Buffer.isBuffer(signature)) {
    throw new Error('Signature must be a Buffer')
  }

  offset += 2 // Leave space for length
  buf.writeUInt16BE(types.toType(sig.typeCovered), offset)
  offset += 2
  buf.writeUInt8(sig.algorithm, offset)
  offset += 1
  buf.writeUInt8(sig.labels, offset)
  offset += 1
  buf.writeUInt32BE(sig.originalTTL, offset)
  offset += 4
  buf.writeUInt32BE(sig.expiration, offset)
  offset += 4
  buf.writeUInt32BE(sig.inception, offset)
  offset += 4
  buf.writeUInt16BE(sig.keyTag, offset)
  offset += 2
  name.encode(sig.signersName, buf, offset)
  offset += name.encode.bytes
  signature.copy(buf, offset, 0, signature.length)
  offset += signature.length

  rrrsig.encode.bytes = offset - oldOffset
  buf.writeUInt16BE(rrrsig.encode.bytes - 2, oldOffset)
  return buf
}

rrrsig.encode.bytes = 0

rrrsig.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset

  var sig = {}
  var length = buf.readUInt16BE(offset)
  offset += 2
  sig.typeCovered = types.toString(buf.readUInt16BE(offset))
  offset += 2
  sig.algorithm = buf.readUInt8(offset)
  offset += 1
  sig.labels = buf.readUInt8(offset)
  offset += 1
  sig.originalTTL = buf.readUInt32BE(offset)
  offset += 4
  sig.expiration = buf.readUInt32BE(offset)
  offset += 4
  sig.inception = buf.readUInt32BE(offset)
  offset += 4
  sig.keyTag = buf.readUInt16BE(offset)
  offset += 2
  sig.signersName = name.decode(buf, offset)
  offset += name.decode.bytes
  sig.signature = buf.slice(offset, oldOffset + length + 2)
  offset += sig.signature.length
  rrrsig.decode.bytes = offset - oldOffset
  return sig
}

rrrsig.decode.bytes = 0

rrrsig.encodingLength = function (sig) {
  return 20 +
    name.encodingLength(sig.signersName) +
    Buffer.byteLength(sig.signature)
}

const rrp = exports.rp = {}

rrp.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(rrp.encodingLength(data))
  if (!offset) offset = 0
  const oldOffset = offset

  offset += 2 // Leave space for length
  name.encode(data.mbox || '.', buf, offset, { mail: true })
  offset += name.encode.bytes
  name.encode(data.txt || '.', buf, offset)
  offset += name.encode.bytes
  rrp.encode.bytes = offset - oldOffset
  buf.writeUInt16BE(rrp.encode.bytes - 2, oldOffset)
  return buf
}

rrp.encode.bytes = 0

rrp.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset

  const data = {}
  offset += 2
  data.mbox = name.decode(buf, offset, { mail: true }) || '.'
  offset += name.decode.bytes
  data.txt = name.decode(buf, offset) || '.'
  offset += name.decode.bytes
  rrp.decode.bytes = offset - oldOffset
  return data
}

rrp.decode.bytes = 0

rrp.encodingLength = function (data) {
  return 2 + name.encodingLength(data.mbox || '.') + name.encodingLength(data.txt || '.')
}

const typebitmap = {}

typebitmap.encode = function (typelist, buf, offset) {
  if (!buf) buf = Buffer.alloc(typebitmap.encodingLength(typelist))
  if (!offset) offset = 0
  const oldOffset = offset

  var typesByWindow = []
  for (var i = 0; i < typelist.length; i++) {
    var typeid = types.toType(typelist[i])
    if (typesByWindow[typeid >> 8] === undefined) {
      typesByWindow[typeid >> 8] = []
    }
    typesByWindow[typeid >> 8][(typeid >> 3) & 0x1F] |= 1 << (7 - (typeid & 0x7))
  }

  for (i = 0; i < typesByWindow.length; i++) {
    if (typesByWindow[i] !== undefined) {
      var windowBuf = Buffer.from(typesByWindow[i])
      buf.writeUInt8(i, offset)
      offset += 1
      buf.writeUInt8(windowBuf.length, offset)
      offset += 1
      windowBuf.copy(buf, offset)
      offset += windowBuf.length
    }
  }

  typebitmap.encode.bytes = offset - oldOffset
  return buf
}

typebitmap.encode.bytes = 0

typebitmap.decode = function (buf, offset, length) {
  if (!offset) offset = 0
  const oldOffset = offset

  var typelist = []
  while (offset - oldOffset < length) {
    var window = buf.readUInt8(offset)
    offset += 1
    var windowLength = buf.readUInt8(offset)
    offset += 1
    for (var i = 0; i < windowLength; i++) {
      var b = buf.readUInt8(offset + i)
      for (var j = 0; j < 8; j++) {
        if (b & (1 << (7 - j))) {
          var typeid = types.toString((window << 8) | (i << 3) | j)
          typelist.push(typeid)
        }
      }
    }
    offset += windowLength
  }

  typebitmap.decode.bytes = offset - oldOffset
  return typelist
}

typebitmap.decode.bytes = 0

typebitmap.encodingLength = function (typelist) {
  var extents = []
  for (var i = 0; i < typelist.length; i++) {
    var typeid = types.toType(typelist[i])
    extents[typeid >> 8] = Math.max(extents[typeid >> 8] || 0, typeid & 0xFF)
  }

  var len = 0
  for (i = 0; i < extents.length; i++) {
    if (extents[i] !== undefined) {
      len += 2 + Math.ceil((extents[i] + 1) / 8)
    }
  }

  return len
}

const rnsec = exports.nsec = {}

rnsec.encode = function (record, buf, offset) {
  if (!buf) buf = Buffer.alloc(rnsec.encodingLength(record))
  if (!offset) offset = 0
  const oldOffset = offset

  offset += 2 // Leave space for length
  name.encode(record.nextDomain, buf, offset)
  offset += name.encode.bytes
  typebitmap.encode(record.rrtypes, buf, offset)
  offset += typebitmap.encode.bytes

  rnsec.encode.bytes = offset - oldOffset
  buf.writeUInt16BE(rnsec.encode.bytes - 2, oldOffset)
  return buf
}

rnsec.encode.bytes = 0

rnsec.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset

  var record = {}
  var length = buf.readUInt16BE(offset)
  offset += 2
  record.nextDomain = name.decode(buf, offset)
  offset += name.decode.bytes
  record.rrtypes = typebitmap.decode(buf, offset, length - (offset - oldOffset))
  offset += typebitmap.decode.bytes

  rnsec.decode.bytes = offset - oldOffset
  return record
}

rnsec.decode.bytes = 0

rnsec.encodingLength = function (record) {
  return 2 +
    name.encodingLength(record.nextDomain) +
    typebitmap.encodingLength(record.rrtypes)
}

const rnsec3 = exports.nsec3 = {}

rnsec3.encode = function (record, buf, offset) {
  if (!buf) buf = Buffer.alloc(rnsec3.encodingLength(record))
  if (!offset) offset = 0
  const oldOffset = offset

  const salt = record.salt
  if (!Buffer.isBuffer(salt)) {
    throw new Error('salt must be a Buffer')
  }

  const nextDomain = record.nextDomain
  if (!Buffer.isBuffer(nextDomain)) {
    throw new Error('nextDomain must be a Buffer')
  }

  offset += 2 // Leave space for length
  buf.writeUInt8(record.algorithm, offset)
  offset += 1
  buf.writeUInt8(record.flags, offset)
  offset += 1
  buf.writeUInt16BE(record.iterations, offset)
  offset += 2
  buf.writeUInt8(salt.length, offset)
  offset += 1
  salt.copy(buf, offset, 0, salt.length)
  offset += salt.length
  buf.writeUInt8(nextDomain.length, offset)
  offset += 1
  nextDomain.copy(buf, offset, 0, nextDomain.length)
  offset += nextDomain.length
  typebitmap.encode(record.rrtypes, buf, offset)
  offset += typebitmap.encode.bytes

  rnsec3.encode.bytes = offset - oldOffset
  buf.writeUInt16BE(rnsec3.encode.bytes - 2, oldOffset)
  return buf
}

rnsec3.encode.bytes = 0

rnsec3.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset

  var record = {}
  var length = buf.readUInt16BE(offset)
  offset += 2
  record.algorithm = buf.readUInt8(offset)
  offset += 1
  record.flags = buf.readUInt8(offset)
  offset += 1
  record.iterations = buf.readUInt16BE(offset)
  offset += 2
  const saltLength = buf.readUInt8(offset)
  offset += 1
  record.salt = buf.slice(offset, offset + saltLength)
  offset += saltLength
  const hashLength = buf.readUInt8(offset)
  offset += 1
  record.nextDomain = buf.slice(offset, offset + hashLength)
  offset += hashLength
  record.rrtypes = typebitmap.decode(buf, offset, length - (offset - oldOffset))
  offset += typebitmap.decode.bytes

  rnsec3.decode.bytes = offset - oldOffset
  return record
}

rnsec3.decode.bytes = 0

rnsec3.encodingLength = function (record) {
  return 8 +
    record.salt.length +
    record.nextDomain.length +
    typebitmap.encodingLength(record.rrtypes)
}

const rds = exports.ds = {}

rds.encode = function (digest, buf, offset) {
  if (!buf) buf = Buffer.alloc(rds.encodingLength(digest))
  if (!offset) offset = 0
  const oldOffset = offset

  const digestdata = digest.digest
  if (!Buffer.isBuffer(digestdata)) {
    throw new Error('Digest must be a Buffer')
  }

  offset += 2 // Leave space for length
  buf.writeUInt16BE(digest.keyTag, offset)
  offset += 2
  buf.writeUInt8(digest.algorithm, offset)
  offset += 1
  buf.writeUInt8(digest.digestType, offset)
  offset += 1
  digestdata.copy(buf, offset, 0, digestdata.length)
  offset += digestdata.length

  rds.encode.bytes = offset - oldOffset
  buf.writeUInt16BE(rds.encode.bytes - 2, oldOffset)
  return buf
}

rds.encode.bytes = 0

rds.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset

  var digest = {}
  var length = buf.readUInt16BE(offset)
  offset += 2
  digest.keyTag = buf.readUInt16BE(offset)
  offset += 2
  digest.algorithm = buf.readUInt8(offset)
  offset += 1
  digest.digestType = buf.readUInt8(offset)
  offset += 1
  digest.digest = buf.slice(offset, oldOffset + length + 2)
  offset += digest.digest.length
  rds.decode.bytes = offset - oldOffset
  return digest
}

rds.decode.bytes = 0

rds.encodingLength = function (digest) {
  return 6 + Buffer.byteLength(digest.digest)
}

const rsshfp = exports.sshfp = {}

rsshfp.getFingerprintLengthForHashType = function getFingerprintLengthForHashType (hashType) {
  switch (hashType) {
    case 1: return 20
    case 2: return 32
  }
}

rsshfp.encode = function encode (record, buf, offset) {
  if (!buf) buf = Buffer.alloc(rsshfp.encodingLength(record))
  if (!offset) offset = 0
  const oldOffset = offset

  offset += 2 // The function call starts with the offset pointer at the RDLENGTH field, not the RDATA one
  buf[offset] = record.algorithm
  offset += 1
  buf[offset] = record.hash
  offset += 1

  const fingerprintBuf = Buffer.from(record.fingerprint.toUpperCase(), 'hex')
  if (fingerprintBuf.length !== rsshfp.getFingerprintLengthForHashType(record.hash)) {
    throw new Error('Invalid fingerprint length')
  }
  fingerprintBuf.copy(buf, offset)
  offset += fingerprintBuf.byteLength

  rsshfp.encode.bytes = offset - oldOffset
  buf.writeUInt16BE(rsshfp.encode.bytes - 2, oldOffset)

  return buf
}

rsshfp.encode.bytes = 0

rsshfp.decode = function decode (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset

  const record = {}
  offset += 2 // Account for the RDLENGTH field
  record.algorithm = buf[offset]
  offset += 1
  record.hash = buf[offset]
  offset += 1

  const fingerprintLength = rsshfp.getFingerprintLengthForHashType(record.hash)
  record.fingerprint = buf.slice(offset, offset + fingerprintLength).toString('hex').toUpperCase()
  offset += fingerprintLength
  rsshfp.decode.bytes = offset - oldOffset
  return record
}

rsshfp.decode.bytes = 0

rsshfp.encodingLength = function (record) {
  return 4 + Buffer.from(record.fingerprint, 'hex').byteLength
}

const rnaptr = exports.naptr = {}

rnaptr.encode = function (data, buf, offset) {
  if (!buf) buf = Buffer.alloc(rnaptr.encodingLength(data))
  if (!offset) offset = 0
  const oldOffset = offset
  offset += 2
  buf.writeUInt16BE(data.order || 0, offset)
  offset += 2
  buf.writeUInt16BE(data.preference || 0, offset)
  offset += 2
  string.encode(data.flags, buf, offset)
  offset += string.encode.bytes
  string.encode(data.services, buf, offset)
  offset += string.encode.bytes
  string.encode(data.regexp, buf, offset)
  offset += string.encode.bytes
  name.encode(data.replacement, buf, offset)
  offset += name.encode.bytes
  rnaptr.encode.bytes = offset - oldOffset
  buf.writeUInt16BE(rnaptr.encode.bytes - 2, oldOffset)
  return buf
}

rnaptr.encode.bytes = 0

rnaptr.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset
  const data = {}
  offset += 2
  data.order = buf.readUInt16BE(offset)
  offset += 2
  data.preference = buf.readUInt16BE(offset)
  offset += 2
  data.flags = string.decode(buf, offset)
  offset += string.decode.bytes
  data.services = string.decode(buf, offset)
  offset += string.decode.bytes
  data.regexp = string.decode(buf, offset)
  offset += string.decode.bytes
  data.replacement = name.decode(buf, offset)
  offset += name.decode.bytes
  rnaptr.decode.bytes = offset - oldOffset
  return data
}

rnaptr.decode.bytes = 0

rnaptr.encodingLength = function (data) {
  return string.encodingLength(data.flags) +
    string.encodingLength(data.services) +
    string.encodingLength(data.regexp) +
    name.encodingLength(data.replacement) + 6
}

const rtlsa = exports.tlsa = {}

rtlsa.encode = function (cert, buf, offset) {
  if (!buf) buf = Buffer.alloc(rtlsa.encodingLength(cert))
  if (!offset) offset = 0
  const oldOffset = offset

  const certdata = cert.certificate
  if (!Buffer.isBuffer(certdata)) {
    throw new Error('Certificate must be a Buffer')
  }

  offset += 2 // Leave space for length
  buf.writeUInt8(cert.usage, offset)
  offset += 1
  buf.writeUInt8(cert.selector, offset)
  offset += 1
  buf.writeUInt8(cert.matchingType, offset)
  offset += 1
  certdata.copy(buf, offset, 0, certdata.length)
  offset += certdata.length

  rtlsa.encode.bytes = offset - oldOffset
  buf.writeUInt16BE(rtlsa.encode.bytes - 2, oldOffset)
  return buf
}

rtlsa.encode.bytes = 0

rtlsa.decode = function (buf, offset) {
  if (!offset) offset = 0
  const oldOffset = offset

  const cert = {}
  const length = buf.readUInt16BE(offset)
  offset += 2
  cert.usage = buf.readUInt8(offset)
  offset += 1
  cert.selector = buf.readUInt8(offset)
  offset += 1
  cert.matchingType = buf.readUInt8(offset)
  offset += 1
  cert.certificate = buf.slice(offset, oldOffset + length + 2)
  offset += cert.certificate.length
  rtlsa.decode.bytes = offset - oldOffset
  return cert
}

rtlsa.decode.bytes = 0

rtlsa.encodingLength = function (cert) {
  return 5 + Buffer.byteLength(cert.certificate)
}

const renc = exports.record = function (type) {
  switch (type.toUpperCase()) {
    case 'A': return ra
    case 'PTR': return rptr
    case 'CNAME': return rcname
    case 'DNAME': return rdname
    case 'TXT': return rtxt
    case 'NULL': return rnull
    case 'AAAA': return raaaa
    case 'SRV': return rsrv
    case 'HINFO': return rhinfo
    case 'CAA': return rcaa
    case 'NS': return rns
    case 'SOA': return rsoa
    case 'MX': return rmx
    case 'OPT': return ropt
    case 'DNSKEY': return rdnskey
    case 'RRSIG': return rrrsig
    case 'RP': return rrp
    case 'NSEC': return rnsec
    case 'NSEC3': return rnsec3
    case 'SSHFP': return rsshfp
    case 'DS': return rds
    case 'NAPTR': return rnaptr
    case 'TLSA': return rtlsa
  }
  return runknown
}

const answer = exports.answer = {}

answer.encode = function (a, buf, offset) {
  if (!buf) buf = Buffer.alloc(answer.encodingLength(a))
  if (!offset) offset = 0

  const oldOffset = offset

  name.encode(a.name, buf, offset)
  offset += name.encode.bytes

  buf.writeUInt16BE(types.toType(a.type), offset)

  if (a.type.toUpperCase() === 'OPT') {
    if (a.name !== '.') {
      throw new Error('OPT name must be root.')
    }
    buf.writeUInt16BE(a.udpPayloadSize || 4096, offset + 2)
    buf.writeUInt8(a.extendedRcode || 0, offset + 4)
    buf.writeUInt8(a.ednsVersion || 0, offset + 5)
    buf.writeUInt16BE(a.flags || 0, offset + 6)

    offset += 8
    ropt.encode(a.options || [], buf, offset)
    offset += ropt.encode.bytes
  } else {
    let klass = classes.toClass(a.class === undefined ? 'IN' : a.class)
    if (a.flush) klass |= FLUSH_MASK // the 1st bit of the class is the flush bit
    buf.writeUInt16BE(klass, offset + 2)
    buf.writeUInt32BE(a.ttl || 0, offset + 4)

    offset += 8
    const enc = renc(a.type)
    enc.encode(a.data, buf, offset)
    offset += enc.encode.bytes
  }

  answer.encode.bytes = offset - oldOffset
  return buf
}

answer.encode.bytes = 0

answer.decode = function (buf, offset) {
  if (!offset) offset = 0

  const a = {}
  const oldOffset = offset

  a.name = name.decode(buf, offset)
  offset += name.decode.bytes
  a.type = types.toString(buf.readUInt16BE(offset))
  if (a.type === 'OPT') {
    a.udpPayloadSize = buf.readUInt16BE(offset + 2)
    a.extendedRcode = buf.readUInt8(offset + 4)
    a.ednsVersion = buf.readUInt8(offset + 5)
    a.flags = buf.readUInt16BE(offset + 6)
    a.flag_do = ((a.flags >> 15) & 0x1) === 1
    a.options = ropt.decode(buf, offset + 8)
    offset += 8 + ropt.decode.bytes
  } else {
    const klass = buf.readUInt16BE(offset + 2)
    a.ttl = buf.readUInt32BE(offset + 4)

    a.class = classes.toString(klass & NOT_FLUSH_MASK)
    a.flush = !!(klass & FLUSH_MASK)

    const enc = renc(a.type)
    a.data = enc.decode(buf, offset + 8)
    offset += 8 + enc.decode.bytes
  }

  answer.decode.bytes = offset - oldOffset
  return a
}

answer.decode.bytes = 0

answer.encodingLength = function (a) {
  const data = (a.data !== null && a.data !== undefined) ? a.data : a.options
  return name.encodingLength(a.name) + 8 + renc(a.type).encodingLength(data)
}

const question = exports.question = {}

question.encode = function (q, buf, offset) {
  if (!buf) buf = Buffer.alloc(question.encodingLength(q))
  if (!offset) offset = 0

  const oldOffset = offset

  name.encode(q.name, buf, offset)
  offset += name.encode.bytes

  buf.writeUInt16BE(types.toType(q.type), offset)
  offset += 2

  buf.writeUInt16BE(classes.toClass(q.class === undefined ? 'IN' : q.class), offset)
  offset += 2

  question.encode.bytes = offset - oldOffset
  return q
}

question.encode.bytes = 0

question.decode = function (buf, offset) {
  if (!offset) offset = 0

  const oldOffset = offset
  const q = {}

  q.name = name.decode(buf, offset)
  offset += name.decode.bytes

  q.type = types.toString(buf.readUInt16BE(offset))
  offset += 2

  q.class = classes.toString(buf.readUInt16BE(offset))
  offset += 2

  const qu = !!(q.class & QU_MASK)
  if (qu) q.class &= NOT_QU_MASK

  question.decode.bytes = offset - oldOffset
  return q
}

question.decode.bytes = 0

question.encodingLength = function (q) {
  return name.encodingLength(q.name) + 4
}

exports.AUTHORITATIVE_ANSWER = 1 << 10
exports.TRUNCATED_RESPONSE = 1 << 9
exports.RECURSION_DESIRED = 1 << 8
exports.RECURSION_AVAILABLE = 1 << 7
exports.AUTHENTIC_DATA = 1 << 5
exports.CHECKING_DISABLED = 1 << 4
exports.DNSSEC_OK = 1 << 15

exports.encode = function (result, buf, offset) {
  const allocing = !buf

  if (allocing) buf = Buffer.alloc(exports.encodingLength(result))
  if (!offset) offset = 0

  const oldOffset = offset

  if (!result.questions) result.questions = []
  if (!result.answers) result.answers = []
  if (!result.authorities) result.authorities = []
  if (!result.additionals) result.additionals = []

  header.encode(result, buf, offset)
  offset += header.encode.bytes

  offset = encodeList(result.questions, question, buf, offset)
  offset = encodeList(result.answers, answer, buf, offset)
  offset = encodeList(result.authorities, answer, buf, offset)
  offset = encodeList(result.additionals, answer, buf, offset)

  exports.encode.bytes = offset - oldOffset

  // just a quick sanity check
  if (allocing && exports.encode.bytes !== buf.length) {
    return buf.slice(0, exports.encode.bytes)
  }

  return buf
}

exports.encode.bytes = 0

exports.decode = function (buf, offset) {
  if (!offset) offset = 0

  const oldOffset = offset
  const result = header.decode(buf, offset)
  offset += header.decode.bytes

  offset = decodeList(result.questions, question, buf, offset)
  offset = decodeList(result.answers, answer, buf, offset)
  offset = decodeList(result.authorities, answer, buf, offset)
  offset = decodeList(result.additionals, answer, buf, offset)

  exports.decode.bytes = offset - oldOffset

  return result
}

exports.decode.bytes = 0

exports.encodingLength = function (result) {
  return header.encodingLength(result) +
    encodingLengthList(result.questions || [], question) +
    encodingLengthList(result.answers || [], answer) +
    encodingLengthList(result.authorities || [], answer) +
    encodingLengthList(result.additionals || [], answer)
}

exports.streamEncode = function (result) {
  const buf = exports.encode(result)
  const sbuf = Buffer.alloc(2)
  sbuf.writeUInt16BE(buf.byteLength)
  const combine = Buffer.concat([sbuf, buf])
  exports.streamEncode.bytes = combine.byteLength
  return combine
}

exports.streamEncode.bytes = 0

exports.streamDecode = function (sbuf) {
  const len = sbuf.readUInt16BE(0)
  if (sbuf.byteLength < len + 2) {
    // not enough data
    return null
  }
  const result = exports.decode(sbuf.slice(2))
  exports.streamDecode.bytes = exports.decode.bytes
  return result
}

exports.streamDecode.bytes = 0

function encodingLengthList (list, enc) {
  let len = 0
  for (let i = 0; i < list.length; i++) len += enc.encodingLength(list[i])
  return len
}

function encodeList (list, enc, buf, offset) {
  for (let i = 0; i < list.length; i++) {
    enc.encode(list[i], buf, offset)
    offset += enc.encode.bytes
  }
  return offset
}

function decodeList (list, enc, buf, offset) {
  for (let i = 0; i < list.length; i++) {
    list[i] = enc.decode(buf, offset)
    offset += enc.decode.bytes
  }
  return offset
}


code:
'use strict'

/*
 * Traditional DNS header OPCODEs (4-bits) defined by IANA in
 * https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-5
 */

exports.toString = function (opcode) {
  switch (opcode) {
    case 0: return 'QUERY'
    case 1: return 'IQUERY'
    case 2: return 'STATUS'
    case 3: return 'OPCODE_3'
    case 4: return 'NOTIFY'
    case 5: return 'UPDATE'
    case 6: return 'OPCODE_6'
    case 7: return 'OPCODE_7'
    case 8: return 'OPCODE_8'
    case 9: return 'OPCODE_9'
    case 10: return 'OPCODE_10'
    case 11: return 'OPCODE_11'
    case 12: return 'OPCODE_12'
    case 13: return 'OPCODE_13'
    case 14: return 'OPCODE_14'
    case 15: return 'OPCODE_15'
  }
  return 'OPCODE_' + opcode
}

exports.toOpcode = function (code) {
  switch (code.toUpperCase()) {
    case 'QUERY': return 0
    case 'IQUERY': return 1
    case 'STATUS': return 2
    case 'OPCODE_3': return 3
    case 'NOTIFY': return 4
    case 'UPDATE': return 5
    case 'OPCODE_6': return 6
    case 'OPCODE_7': return 7
    case 'OPCODE_8': return 8
    case 'OPCODE_9': return 9
    case 'OPCODE_10': return 10
    case 'OPCODE_11': return 11
    case 'OPCODE_12': return 12
    case 'OPCODE_13': return 13
    case 'OPCODE_14': return 14
    case 'OPCODE_15': return 15
  }
  return 0
}

license: mit


code:
'use strict'

exports.toString = function (type) {
  switch (type) {
    // list at
    // https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml#dns-parameters-11
    case 1: return 'LLQ'
    case 2: return 'UL'
    case 3: return 'NSID'
    case 5: return 'DAU'
    case 6: return 'DHU'
    case 7: return 'N3U'
    case 8: return 'CLIENT_SUBNET'
    case 9: return 'EXPIRE'
    case 10: return 'COOKIE'
    case 11: return 'TCP_KEEPALIVE'
    case 12: return 'PADDING'
    case 13: return 'CHAIN'
    case 14: return 'KEY_TAG'
    case 26946: return 'DEVICEID'
  }
  if (type < 0) {
    return null
  }
  return `OPTION_${type}`
}

exports.toCode = function (name) {
  if (typeof name === 'number') {
    return name
  }
  if (!name) {
    return -1
  }
  switch (name.toUpperCase()) {
    case 'OPTION_0': return 0
    case 'LLQ': return 1
    case 'UL': return 2
    case 'NSID': return 3
    case 'OPTION_4': return 4
    case 'DAU': return 5
    case 'DHU': return 6
    case 'N3U': return 7
    case 'CLIENT_SUBNET': return 8
    case 'EXPIRE': return 9
    case 'COOKIE': return 10
    case 'TCP_KEEPALIVE': return 11
    case 'PADDING': return 12
    case 'CHAIN': return 13
    case 'KEY_TAG': return 14
    case 'DEVICEID': return 26946
    case 'OPTION_65535': return 65535
  }
  const m = name.match(/_(\d+)$/)
  if (m) {
    return parseInt(m[1], 10)
  }
  return -1
}


dns-packet

description: An abstract-encoding compliant module for encoding / decoding DNS packets

author: Mathias Buus

license: MIT

repository: mafintosh/dns-packet

clean: rm -rf coverage .nyc_output/

lint: eslint --color *.js examples/*.js

pretest: npm run lint

test: tape test.js

coverage: nyc -r html npm test

keywords: dns packet encodings encoding encoder abstract-encoding


code:
'use strict'

/*
 * Traditional DNS header RCODEs (4-bits) defined by IANA in
 * https://www.iana.org/assignments/dns-parameters/dns-parameters.xhtml
 */

exports.toString = function (rcode) {
  switch (rcode) {
    case 0: return 'NOERROR'
    case 1: return 'FORMERR'
    case 2: return 'SERVFAIL'
    case 3: return 'NXDOMAIN'
    case 4: return 'NOTIMP'
    case 5: return 'REFUSED'
    case 6: return 'YXDOMAIN'
    case 7: return 'YXRRSET'
    case 8: return 'NXRRSET'
    case 9: return 'NOTAUTH'
    case 10: return 'NOTZONE'
    case 11: return 'RCODE_11'
    case 12: return 'RCODE_12'
    case 13: return 'RCODE_13'
    case 14: return 'RCODE_14'
    case 15: return 'RCODE_15'
  }
  return 'RCODE_' + rcode
}

exports.toRcode = function (code) {
  switch (code.toUpperCase()) {
    case 'NOERROR': return 0
    case 'FORMERR': return 1
    case 'SERVFAIL': return 2
    case 'NXDOMAIN': return 3
    case 'NOTIMP': return 4
    case 'REFUSED': return 5
    case 'YXDOMAIN': return 6
    case 'YXRRSET': return 7
    case 'NXRRSET': return 8
    case 'NOTAUTH': return 9
    case 'NOTZONE': return 10
    case 'RCODE_11': return 11
    case 'RCODE_12': return 12
    case 'RCODE_13': return 13
    case 'RCODE_14': return 14
    case 'RCODE_15': return 15
  }
  return 0
}


code:
'use strict'

exports.toString = function (type) {
  switch (type) {
    case 1: return 'A'
    case 10: return 'NULL'
    case 28: return 'AAAA'
    case 18: return 'AFSDB'
    case 42: return 'APL'
    case 257: return 'CAA'
    case 60: return 'CDNSKEY'
    case 59: return 'CDS'
    case 37: return 'CERT'
    case 5: return 'CNAME'
    case 49: return 'DHCID'
    case 32769: return 'DLV'
    case 39: return 'DNAME'
    case 48: return 'DNSKEY'
    case 43: return 'DS'
    case 55: return 'HIP'
    case 13: return 'HINFO'
    case 45: return 'IPSECKEY'
    case 25: return 'KEY'
    case 36: return 'KX'
    case 29: return 'LOC'
    case 15: return 'MX'
    case 35: return 'NAPTR'
    case 2: return 'NS'
    case 47: return 'NSEC'
    case 50: return 'NSEC3'
    case 51: return 'NSEC3PARAM'
    case 12: return 'PTR'
    case 46: return 'RRSIG'
    case 17: return 'RP'
    case 24: return 'SIG'
    case 6: return 'SOA'
    case 99: return 'SPF'
    case 33: return 'SRV'
    case 44: return 'SSHFP'
    case 32768: return 'TA'
    case 249: return 'TKEY'
    case 52: return 'TLSA'
    case 250: return 'TSIG'
    case 16: return 'TXT'
    case 252: return 'AXFR'
    case 251: return 'IXFR'
    case 41: return 'OPT'
    case 255: return 'ANY'
  }
  return 'UNKNOWN_' + type
}

exports.toType = function (name) {
  switch (name.toUpperCase()) {
    case 'A': return 1
    case 'NULL': return 10
    case 'AAAA': return 28
    case 'AFSDB': return 18
    case 'APL': return 42
    case 'CAA': return 257
    case 'CDNSKEY': return 60
    case 'CDS': return 59
    case 'CERT': return 37
    case 'CNAME': return 5
    case 'DHCID': return 49
    case 'DLV': return 32769
    case 'DNAME': return 39
    case 'DNSKEY': return 48
    case 'DS': return 43
    case 'HIP': return 55
    case 'HINFO': return 13
    case 'IPSECKEY': return 45
    case 'KEY': return 25
    case 'KX': return 36
    case 'LOC': return 29
    case 'MX': return 15
    case 'NAPTR': return 35
    case 'NS': return 2
    case 'NSEC': return 47
    case 'NSEC3': return 50
    case 'NSEC3PARAM': return 51
    case 'PTR': return 12
    case 'RRSIG': return 46
    case 'RP': return 17
    case 'SIG': return 24
    case 'SOA': return 6
    case 'SPF': return 99
    case 'SRV': return 33
    case 'SSHFP': return 44
    case 'TA': return 32768
    case 'TKEY': return 249
    case 'TLSA': return 52
    case 'TSIG': return 250
    case 'TXT': return 16
    case 'AXFR': return 252
    case 'IXFR': return 251
    case 'OPT': return 41
    case 'ANY': return 255
    case '*': return 255
  }
  if (name.toUpperCase().startsWith('UNKNOWN_')) return parseInt(name.slice(8))
  return 0
}


code:
v3.0.0 - November 9, 2018

* 0b5a8c7 Breaking: drop support for Node < 6 (#223) (Kai Cataldo)
* a05e9f2 Upgrade: eslint-release@1.0.0 (#220) (Teddy Katz)
* 36ed027 Chore: upgrade coveralls to ^3.0.1 (#213) (Teddy Katz)
* 8667e34 Upgrade: eslint-release@^0.11.1 (#210) (Kevin Partington)

v2.1.0 - January 6, 2018

* 827f314 Update: support node ranges (fixes #89) (#190) (Teddy Katz)

v2.0.2 - November 25, 2017

* 5049ee3 Fix: Remove redundant LICENSE/README names from files (#203) (Kevin Partington)

v2.0.1 - November 10, 2017

* 009f33d Fix: Making sure union type stringification respects compact flag (#199) (Mitermayer Reis)
* 19da935 Use native String.prototype.trim instead of a custom implementation. (#201) (Rouven Weßling)
* e3a011b chore: add mocha.opts to restore custom mocha config (Jason Kurian)
* d888200 chore: adds nyc and a newer version of mocha to accurately report coverage (Jason Kurian)
* 6b210a8 fix: support type expression for @this tag (fixes #181) (#182) (Frédéric Junod)
* 1c4a4c7 fix: Allow array indexes in names (#193) (Tom MacWright)
* 9aed54d Fix incorrect behavior when arrow functions are used as default values (#189) (Gaurab Paul)
* 9efb6ca Upgrade: Use Array.isArray instead of isarray package (#195) (medanat)

v2.0.0 - November 15, 2016

* 7d7c5f1 Breaking: Re-license to Apache 2 (fixes #176) (#178) (Nicholas C. Zakas)
* 5496132 Docs: Update license copyright (Nicholas C. Zakas)

v1.5.0 - October 13, 2016

* e33c6bb Update: Add support for BooleanLiteralType (#173) (Erik Arvidsson)

v1.4.0 - September 13, 2016

* d7426e5 Update: add ability to parse optional properties in typedefs (refs #5) (#174) (ikokostya)

v1.3.0 - August 22, 2016

* 12c7ad9 Update: Add support for numeric and string literal types (fixes #156) (#172) (Andrew Walter)

v1.2.3 - August 16, 2016

* b96a884 Build: Add CI release script (Nicholas C. Zakas)
* 8d9b3c7 Upgrade: Upgrade esutils to v2.0.2 (fixes #170) (#171) (Emeegeemee)

v1.2.2 - May 19, 2016

* ebe0b08 Fix: Support case insensitive tags (fixes #163) (#164) (alberto)
* 8e6d81e Chore: Remove copyright and license from headers (Nicholas C. Zakas)
* 79035c6 Chore: Include jQuery Foundation copyright (Nicholas C. Zakas)
* 06910a7 Fix: Preserve whitespace in default param string values (fixes #157) (Kai Cataldo)

v1.2.1 - March 29, 2016

* 1f54014 Fix: allow hyphens in names (fixes #116) (Kai Cataldo)
* bbee469 Docs: Add issue template (Nicholas C. Zakas)

v1.2.0 - February 19, 2016

* 18136c5 Build: Cleanup build system (Nicholas C. Zakas)
* b082f85 Update: Add support for slash in namepaths (fixes #100) (Ryan Duffy)
* def53a2 Docs: Fix typo in option lineNumbers (Daniel Tschinder)
* e2cbbc5 Update: Bump isarray to v1.0.0 (Shinnosuke Watanabe)
* ae07aa8 Fix: Allow whitespace in optional param with default value (fixes #141) (chris)

v1.1.0 - January 6, 2016

* Build: Switch to Makefile.js (Nicholas C. Zakas)
* New: support name expression for @this tag (fixes #143) (Tim Schaub)
* Build: Update ESLint settings (Nicholas C. Zakas)

v1.0.0 - December 21, 2015

* New: parse caption tags in examples into separate property. (fixes #131) (Tom MacWright)

v0.7.2 - November 27, 2015

* Fix: Line numbers for some tags (fixes #138) Fixing issue where input was not consumed via advance() but was skipped when parsing tags resulting in sometimes incorrect reported lineNumber. (TEHEK)
* Build: Add missing linefix package (Nicholas C. Zakas)

v0.7.1 - November 13, 2015

* Update: Begin switch to Makefile.js (Nicholas C. Zakas)
* Fix: permit return tag without type (fixes #136) (Tom MacWright)
* Fix: package.json homepage field (Bogdan Chadkin)
* Fix: Parse array default syntax. Fixes #133 (Tom MacWright)
* Fix: Last tag always has \n in the description (fixes #87) (Burak Yigit Kaya)
* Docs: Add changelog (Nicholas C. Zakas)

v0.7.0 - September 21, 2015

* Docs: Update README with new info (fixes #127) (Nicholas C. Zakas)
* Fix: Parsing fix for param with arrays and properties (fixes #111) (Gyandeep Singh)
* Build: Add travis build (fixes #123) (Gyandeep Singh)
* Fix: Parsing of parameter name without a type (fixes #120) (Gyandeep Singh)
* New: added preserveWhitespace option (Aleks Totic)
* New: Add "files" entry to only deploy select files (Rob Loach)
* New: Add support and tests for typedefs. Refs #5 (Tom MacWright)


code:
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code:
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright
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code:
[![NPM version][npm-image]][npm-url]
[![build status][travis-image]][travis-url]
[![Test coverage][coveralls-image]][coveralls-url]
[![Downloads][downloads-image]][downloads-url]
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# Doctrine

Doctrine is a [JSDoc](http://usejsdoc.org) parser that parses documentation comments from JavaScript (you need to pass in the comment, not a whole JavaScript file).

## Installation

You can install Doctrine using [npm](https://npmjs.com):

```
$ npm install doctrine --save-dev
```

Doctrine can also be used in web browsers using [Browserify](http://browserify.org).

## Usage

Require doctrine inside of your JavaScript:

```js
var doctrine = require("doctrine");
```

### parse()

The primary method is `parse()`, which accepts two arguments: the JSDoc comment to parse and an optional options object. The available options are:

* `unwrap` - set to `true` to delete the leading `/**`, any `*` that begins a line, and the trailing `*/` from the source text. Default: `false`.
* `tags` - an array of tags to return. When specified, Doctrine returns only tags in this array. For example, if `tags` is `["param"]`, then only `@param` tags will be returned. Default: `null`.
* `recoverable` - set to `true` to keep parsing even when syntax errors occur. Default: `false`.
* `sloppy` - set to `true` to allow optional parameters to be specified in brackets (`@param {string} [foo]`). Default: `false`.
* `lineNumbers` - set to `true` to add `lineNumber` to each node, specifying the line on which the node is found in the source. Default: `false`.
* `range` - set to `true` to add `range` to each node, specifying the start and end index of the node in the original comment. Default: `false`.

Here's a simple example:

```js
var ast = doctrine.parse(
    [
        "/**",
        " * This function comment is parsed by doctrine",
        " * @param {{ok:String}} userName",
        "*/"
    ].join('\n'), { unwrap: true });
```

This example returns the following AST:

    {
        "description": "This function comment is parsed by doctrine",
        "tags": [
            {
                "title": "param",
                "description": null,
                "type": {
                    "type": "RecordType",
                    "fields": [
                        {
                            "type": "FieldType",
                            "key": "ok",
                            "value": {
                                "type": "NameExpression",
                                "name": "String"
                            }
                        }
                    ]
                },
                "name": "userName"
            }
        ]
    }

See the [demo page](http://eslint.org/doctrine/demo/) more detail.

## Team

These folks keep the project moving and are resources for help:

* Nicholas C. Zakas ([@nzakas](https://github.com/nzakas)) - project lead
* Yusuke Suzuki ([@constellation](https://github.com/constellation)) - reviewer

## Contributing

Issues and pull requests will be triaged and responded to as quickly as possible. We operate under the [ESLint Contributor Guidelines](http://eslint.org/docs/developer-guide/contributing), so please be sure to read them before contributing. If you're not sure where to dig in, check out the [issues](https://github.com/eslint/doctrine/issues).

## Frequently Asked Questions

### Can I pass a whole JavaScript file to Doctrine?

No. Doctrine can only parse JSDoc comments, so you'll need to pass just the JSDoc comment to Doctrine in order to work.

### License

#### doctrine

Copyright JS Foundation and other contributors, https://js.foundation

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

    http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.

#### esprima

some of functions is derived from esprima

Copyright (C) 2012, 2011 [Ariya Hidayat](http://ariya.ofilabs.com/about)
 (twitter: [@ariyahidayat](http://twitter.com/ariyahidayat)) and other contributors.

Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:

  * Redistributions of source code must retain the above copyright
    notice, this list of conditions and the following disclaimer.

  * Redistributions in binary form must reproduce the above copyright
    notice, this list of conditions and the following disclaimer in the
    documentation and/or other materials provided with the distribution.

THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
ARE DISCLAIMED. IN NO EVENT SHALL <COPYRIGHT HOLDER> BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

#### closure-compiler

some of extensions is derived from closure-compiler

Apache License
Version 2.0, January 2004
http://www.apache.org/licenses/

### Where to ask for help?

Join our [Chatroom](https://gitter.im/eslint/doctrine)

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