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dnsd

(★ 267)

Dynamic authoritative name server

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최종 버전 다운로드 (.zip)

- aaaa-query
- aaaa-response
- ds-query
- ds-response
- dynamic-update
- edns-query
- foo.iriscouch.com-query
- foo.iriscouch.com-response
- ipv6_ptr-query
- iriscouch.com-query
- iriscouch.com-response
- oreilly.com-query
- oreilly.com-response
- ptr-query
- ptr-response
- registry.npmjs.org-response
- srv-query
- srv-response
- txt-query
- txt-response
- www.company.example-query
- www.company.example-response
- www.microsoft.com-query
- www.microsoft.com-response
- api.js
- convenience.js
- message.js
- print.js
- server.js
- null-server.js
.gitignore
constants.js
convenient.js
encode.js
LICENSE
message.js
named.js
package.json
parse.js
README.md
server.js

# 설치 가이드

1. 코드 내려받기

git clone https://github.com/iriscouch/dnsd

깃허브에서 프로젝트 코드 전체를 내 컴퓨터로 내려받습니다.

cd dnsd

방금 내려받은 프로젝트 폴더 안으로 이동합니다.

2. Node.js

쉬움 추천

사전 준비물

Git GitHub에서 프로젝트 코드를 내려받으려면 필요합니다.
Node.js npm 명령어를 쓰려면 Node.js가 설치되어 있어야 합니다. LTS(장기지원) 버전을 추천합니다.

$ npm install dnsd

package.json에 명시된 라이브러리들을 내려받아 설치합니다.

✅ 명령어 실행 후 터미널에 나타나는 주소(보통 http://localhost:3000 형태)를 브라우저에서 열어보세요.

이 레포의 README에 적힌 실제 명령어를 그대로 가져왔습니다.

// repository documentation

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# dnsd: DNS encoder, decoder, and server

*dnsd* is a Node.js package for working with DNS. It converts binary DNS messages to and from convenient JavaScript objects; and it provides a server API, for running a custom name server.

*dnsd* is available as an npm module.

$ npm install dnsd

## Example: Running a server

This simple DNS server responds with an "A" (address) record of `1.2.3.4` for every request.

```javascript
var dnsd = require('dnsd')
dnsd.createServer(function(req, res) {
  res.end('1.2.3.4')
}).listen(5353, '127.0.0.1')
console.log('Server running at 127.0.0.1:5353')
```

Now test your server:

$ dig @localhost -p 5353 foo.example A

; <<>> DiG 9.8.1-P1 <<>> @localhost -p 5353 foo.example A
    ; (1 server found)
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 27955
    ;; flags: qr rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
    ;; WARNING: recursion requested but not available

;; QUESTION SECTION:
    ;foo.example.			IN	A

;; ANSWER SECTION:
    foo.example.		3600	IN	A	1.2.3.4

;; Query time: 1 msec
    ;; SERVER: 127.0.0.1#5353(127.0.0.1)
    ;; WHEN: Wed Aug  8 05:10:40 2012
    ;; MSG SIZE  rcvd: 45

This example logs all requests. For address (A) queries, it returns two records, with a random TTL, and the final octet of the IP address is the length of the hostname queried.

```javascript
var dnsd = require('dnsd')

var server = dnsd.createServer(handler)
server.zone('example.com', 'ns1.example.com', 'us@example.com', 'now', '2h', '30m', '2w', '10m')
      .listen(5353, '127.0.0.1')
console.log('Server running at 127.0.0.1:5353')

function handler(req, res) {
  console.log('%s:%s/%s %j', req.connection.remoteAddress, req.connection.remotePort, req.connection.type, req)

var question = res.question[0]
    , hostname = question.name
    , length = hostname.length
    , ttl = Math.floor(Math.random() * 3600)

if(question.type == 'A') {
    res.answer.push({name:hostname, type:'A', data:"1.1.1."+length, 'ttl':ttl})
    res.answer.push({name:hostname, type:'A', data:"2.2.2."+length, 'ttl':ttl})
  }
  res.end()
}
```

Test the SOA response:

$ dig @localhost -p 5353 example.com soa

; <<>> DiG 9.8.1-P1 <<>> @localhost -p 5353 example.com soa
    ; (1 server found)
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 30176
    ;; flags: qr aa rd; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 0
    ;; WARNING: recursion requested but not available

;; QUESTION SECTION:
    ;example.com.			IN	SOA

;; ANSWER SECTION:
    example.com.		600	IN	SOA	ns1.example.com. us.example.com. 1344403648 7200 1800 1209600 600

;; Query time: 5 msec
    ;; SERVER: 127.0.0.1#5353(127.0.0.1)
    ;; WHEN: Wed Aug  8 05:27:32 2012
    ;; MSG SIZE  rcvd: 72

And test the address (A) response:

$ dig @localhost -p 5353 example.com a

; <<>> DiG 9.8.1-P1 <<>> @localhost -p 5353 example.com a
    ; (1 server found)
    ;; global options: +cmd
    ;; Got answer:
    ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 19419
    ;; flags: qr aa rd; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 0
    ;; WARNING: recursion requested but not available

;; QUESTION SECTION:
    ;example.com.			IN	A

;; ANSWER SECTION:
    example.com.		1222	IN	A	1.1.1.11
    example.com.		1222	IN	A	2.2.2.11

;; Query time: 1 msec
    ;; SERVER: 127.0.0.1#5353(127.0.0.1)
    ;; WHEN: Wed Aug  8 05:27:34 2012
    ;; MSG SIZE  rcvd: 61

Server output for these queries:

Server running at 127.0.0.1:5353
    127.0.0.1:34427/udp4 {"id":30176,"type":"request","responseCode":0,"opcode":"query","authoritative":false,"truncated":false,"recursion_desired":true,"recursion_available":false,"authenticated":false,"checking_disabled":false,"question":[{"name":"example.com","type":"SOA","class":"IN"}]}
    127.0.0.1:59596/udp4 {"id":19419,"type":"request","responseCode":0,"opcode":"query","authoritative":false,"truncated":false,"recursion_desired":true,"recursion_available":false,"authenticated":false,"checking_disabled":false,"question":[{"name":"example.com","type":"A","class":"IN"}]}

## Example: MX Records
This is an example if you need to route your mail server with an MX record.

```javascript
// Example MX response with dnsd
//
// To test:
// 1. Run this program
// 2. dig @localhost -p 5353 example.com mx
 
var dnsd = require('dnsd')
 
var server = dnsd.createServer(handler)
server.zone('example.com', 'ns1.example.com', 'us@example.com', 'now', '2h', '30m', '2w', '10m')
server.listen(5353, '127.0.0.1')
console.log('Listening at 127.0.0.1:5353')
 
function handler(req, res) {
  var question = res.question && res.question[0]
 
  if(question.type != 'MX')
    return res.end()
 
  console.log('MX lookup for domain: %s', question.name)
  res.answer.push({'name':question.name, 'type':'MX', 'data':[10, 'mail.example.com']})
  res.answer.push({'name':question.name, 'type':'MX', 'data':[20, 'mail.backupexample.com']})
  
  return res.end()
}
```

The MX data attribute needs to be an Array to work properly, the first value is the priority, the second is the server.
This server name must be a domain string and not an IP address. Make sure you have an A record or CNAME setup for this.

See http://support.google.com/a/bin/answer.py?hl=en&answer=140034 for more info on MX records and configuration.

## Example: Parse a message

```javascript
var fs = require('fs')
var dnsd = require('dnsd')

var msg_file = require.resolve('dnsd/_test_data/registry.npmjs.org-response')
  , msg_data = fs.readFileSync(msg_file)
  , message = dnsd.parse(msg_data)

console.dir(message)
```

Output

```javascript
{ id: 34233,
  type: 'response',
  responseCode: 0,
  opcode: 'query',
  authoritative: false,
  truncated: false,
  recursion_desired: true,
  recursion_available: true,
  authenticated: false,
  checking_disabled: false,
  question: [ { name: 'registry.npmjs.org', type: 'A', class: 'IN' } ],
  answer:
   [ { name: 'registry.npmjs.org',
       type: 'CNAME',
       class: 'IN',
       ttl: 85,
       data: 'isaacs.iriscouch.net' },
     { name: 'isaacs.iriscouch.net',
       type: 'CNAME',
       class: 'IN',
       ttl: 2821,
       data: 'ec2-23-23-147-24.compute-1.amazonaws.com' },
     { name: 'ec2-23-23-147-24.compute-1.amazonaws.com',
       type: 'A',
       class: 'IN',
       ttl: 356336,
       data: '23.23.147.24' } ] }
```

## Example: Encode a message

```javascript
var dnsd = require('dnsd')

var questions = [ {name:'example.com', class:'IN', type:'TXT'} ]
  , message = {type:'query', id:123, opcode:'query', recursion_desired:true, question:questions}
  , msg_data = dnsd.binify(message)

console.log('Encoded = %j', Array.prototype.slice.apply(msg_data))

message = dnsd.parse(msg_data)

console.log('Round trip:')
console.dir(message)
```

Output:

```javascript
Encoded = [0,123,1,0,0,1,0,0,0,0,0,0,7,101,120,97,109,112,108,101,3,99,111,109,0,0,16,0,1]
Round trip:
{ id: 123,
  type: 'request',
  responseCode: 0,
  opcode: 'query',
  authoritative: false,
  truncated: false,
  recursion_desired: true,
  recursion_available: false,
  authenticated: false,
  checking_disabled: false,
  question: [ { name: 'example.com', type: 'TXT', class: 'IN' } ] }
```

## Defaults

`dnsd` is [defaultable][def]. The option `convenient` (`true` by default) adds convenience code when running a server.  Convenience mode adds several features, mostly to build standards-compliant name servers.

```javascript
var dnsd_easy = require('dnsd')
var dnsd_hard = dnsd_easy.defaults({convenient: false})
```

First, your handler's response object already has `.type = "response"` set; then there are many helpers processing your response:

* You can pass a value to `res.end()`, with special handling depending on type:
  * Array: those values will be added to the `res.answer` section.
  * Object: that object will be sent as a response (`res` is unused).
  * String: the response will add an anser `A` record with your value as the IP address.
* Automatically respond to `SOA` queries with the `SOA` record.
* Responses to an `A` query with no answers will add the `SOA` record to the response.
* If the response records are missing a TTL, use the one from the `.zone()` definition (the `SOA` record)

Without convenience mode, dnsd will simply send your response verbatim, as you define it (or throw an encoding error for missing or bad data).

## Tests

Follow uses [node-tap][tap]. If you clone this Git repository, tap is included.

$ tap test
    ok test/api.js ........................................ 10/10
    ok test/convenience.js ................................ 22/22
    ok test/message.js .................................. 176/176
    ok test/print.js ...................................... 10/10
    ok test/server.js ..................................... 35/35
    total ............................................... 253/253

ok

## License

Apache 2.0

See the [Apache 2.0 license](dnsd/blob/master/LICENSE).

[tap]: https://github.com/isaacs/node-tap
[def]: https://github.com/iriscouch/defaultable