dns-lookup-sync

       

       

       

       

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Synchronous version of dnsPromises.lookup

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• 1. Installation
• 2. Usage
  • 2.1. hostname
  • 2.2. options
  • 2.3. return
• 3. License
• 4. Limitations
• 5. Caveats

1. Installation

npm install dns-lookup-sync

2. Usage

Try with Replit.

The API is identical to dnsPromises.lookup, with the promise being unwrapped in the return type to achieve synchronicity.

dnsLookupSync(hostname, options);

Examples (click to view)

Looking up 'localhost' with default options

const dnsLookupSync = require('dns-lookup-sync');

console.log(dnsLookupSync('localhost'));

// Sample output:
// { address: '127.0.0.1', family: 4 }

Looking up a list of addresses from 'www.google.com'

const dnsLookupSync = require('dns-lookup-sync');

console.log(dnsLookupSync('www.google.com', { all: true }));

// Sample output:
// [
//   { address: '172.217.167.100', family: 4 },
//   { address: '2404:6800:4006:80b::2004', family: 6 }
// ]

2.1. hostname

Hostname string to look up. For example,

• 'localhost'
• 'www.google.com'

2.2. options

If an integer is passed, for example 4, it is equivalent to passing the object { family: 4 }.

Option	Description	Example	Default
family number	The record family. Must be 4, 6, or 0. The value 0 indicates that IPv4 and IPv6 addresses are both returned.	4	0
hints number	One or more supported getaddrinfo flags. Multiple flags may be passed by bitwise ORing their values.	dns.ADDRCONFIG	undefined
all boolean	When true, the dnsLookupSync will return all addresses in an array. Otherwise, returns a single address	true	false
verbatim boolean	When true, the returns the IPv4 and IPv6 addresses in the order the DNS resolver returned them. When false, IPv4 addresses are placed before IPv6 addresses.	true	see docs

2.3. return

By default, i.e. options.all === false, a LookupAddress of the form

{ address: string, family: number };

is returned. For example localhost may resolve to:

{ address: '127.0.0.1', family: 4 }

Otherwise, an array of LookupAddress is returned. For example, www.google.com may resolve to:

[
  { address: '142.250.204.4', family: 4 },
  { address: '2404:6800:4006:814::2004', family: 6 }
]

3. License

Massachusetts Institute of Technology (MIT)

Copyright (c) 2023 Khiet Tam Nguyen

Permission is hereby granted, free of charge, to any person obtaining a
copy of this software and associated documentation files (the “Software”),
to deal in the Software without restriction, including without limitation
the rights to use, copy, modify, merge, publish, distribute, sublicense,
and/or sell copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
DEALINGS IN THE SOFTWARE.

4. Limitations

There are currently no known limitations.

5. Caveats

This module was inspired by dns-sync, although focuses primarily on providing the most up-to-date version of dnsPromises.lookup in a synchronous manner.