bouke / dns

Swift implementation of DNS Records / RR

DNS Record Types

A Swift implementation of DNS Record Types. Used for example in mDNS / NetService.

Usage

// Encoding a message
let request = Message(
    type: .query,
    questions: [Question(name: "apple.com.", type: .pointer)]
)
let requestData = try request.serialize()

// Not shown here: send to DNS server over UDP, receive reply.

// Decoding a message
let responseData = Data()
let response = try Message.init(deserialize: responseData)
print(response.answers.first)

Credits

This library was written by Bouke Haarsma.

dns's Issues

CNAME support

Replace UInt16 InternetClass with Enum

See RFC; i.e. IN / CH / HS

Support truncation

UDP DNS messages are limited to 512 bytes. If messages are over 512 bytes, the message is cut-off at 512 bytes and the truncation bit is set. Currently the bit is parsed, but the message isn't handled differently, resulting in a parsing failure. The correct way here would be parsing only a partial message without throwing.

The other way around should also be supported, cutting off messages when truncation is supported.

Also, I need to read up on the spec to see how truncation actually works.

Replace response true/false with something like enum request/response

So instead of:

Header(response: false)

You'd write:

Header(type: .request)

Is it okay that fuzz tests fail?

Hi. I enabled the fuzz tests and swift test always crashes. Is this okay (like, the library should fail when Message(deserialize: data) finds that data is corrupted), or is it a bug?

I'm on Linux, Swift 4.1

Unicode Support

Hi!

I'm using DNS as a dependency of HAP in a Linux box. I'm getting error logs when replying to DNS Messages because of unicode encoding not supported. Nearly all of my members of my family have accents on their names, so their iDevices, shared libraries, and even some rooms, like "baño" have them...

Is unicode not supported by design or is it simply not implemented? If you can give me some pointers maybe I can try to fix it.

Thanks in advance!

Add support for CAA record

Hi!

Is it possible to add support for parsing the CAA of the lookup?

https://support.dnsimple.com/articles/caa-record/

Unable to Use Libary

Hello Everyone,
I am unable to use this library. would be great to get some help.

I found out, that what I need to use is resolving a DNS SRV Records.
so what I did was using the

func testReadMe() throws {
    // If the code below doesn't work, also update the README.md to
    // demonstrate the changes in the API.
    let request = Message(
        type: .query,
        questions: [Question(name: "_sip._tls", type: .service)]  //Changed this to Service
    )
    let requestData = try request.serialize()

    // Not shown here: send to DNS server over UDP, receive reply.
    let responseData = requestData

    // Decoding a message
    let response = try Message(deserialize: responseData)
    print(response.answers.first ?? "No answers")
}

1. This is not using the DNS Search List, as far as I can see
2. This is not Returning any result.

What is wrong here?

Error found during fuzzing

The following message could not be deserialized:

000084000001000200000002085f61692e706c6179045f746370065f6c6f63616c00000c0001c00c000c0001000000780013076578616d706c65085f616972706c6179c015c03200210001000000780015000000001b58076578616d706c65056c6f63616c00c057000100010000007800040a000102c00c000c000100000078000c0b68656c6c6f3d776f726c64

Xcode reports INVOP in Bytes.swift:25 (let step = data[position]).

Use Custom DNS server to query from

How can we specify custom dns server to query from?

Wrong IP address decoding

Environment:
SPM.
Package version 1.2.0
macOS 10.15.6.

When I use DNS messages with debug configuration everything looks good, but once I switch to release, IP addresses could not be parsed:

Release build:

Request: DNS Request(id: 0, authoritativeAnswer: true, truncation: false, recursionDesired: true, recursionAvailable: false, questions: [DNS.Question(name: "amazon.com", type: A, unique: true, internetClass: A)], answers: [], authorities: [], additional: [])
Response: DNS Response(id: 0, returnCode: 0, authoritativeAnswer: false, truncation: false, recursionDesired: true, recursionAvailable: true, questions: [DNS.Question(name: "amazon.com.", type: A, unique: false, internetClass: A)], answers: [DNS.HostRecord<DNS.IPv4>(name: "amazon.com.", unique: false, internetClass: A, ttl: 31, ip: �[�ޭ�), DNS.HostRecord<DNS.IPv4>(name: "amazon.com.", unique: false, internetClass: A, ttl: 31, ip: �[�ޭ�), DNS.HostRecord<DNS.IPv4>(name: "amazon.com.", unique: false, internetClass: A, ttl: 31, ip: �[�ޭ�)], authorities: [], additional: [])

Debug build:

Request: DNS Request(id: 0, authoritativeAnswer: true, truncation: false, recursionDesired: true, recursionAvailable: false, questions: [DNS.Question(name: "amazon.com", type: A, unique: true, internetClass: A)], answers: [], authorities: [], additional: [])
Response: DNS Response(id: 0, returnCode: 0, authoritativeAnswer: false, truncation: false, recursionDesired: true, recursionAvailable: true, questions: [DNS.Question(name: "amazon.com.", type: A, unique: false, internetClass: A)], answers: [DNS.HostRecord<DNS.IPv4>(name: "amazon.com.", unique: false, internetClass: A, ttl: 55, ip: 176.32.103.205), DNS.HostRecord<DNS.IPv4>(name: "amazon.com.", unique: false, internetClass: A, ttl: 55, ip: 176.32.98.166), DNS.HostRecord<DNS.IPv4>(name: "amazon.com.", unique: false, internetClass: A, ttl: 55, ip: 205.251.242.103)], authorities: [], additional: [])

I need some tome to investigate it more and get the real cause, but as far as I can see now, this this PR https://github.com/Bouke/DNS/pull/25/files fixes the problem.

Simplify cyclic reference check

limitedBy could use startPosition, not needing the cyclic reference check

DNS/Sources/DNS/Bytes.swift

Line 26 in 328a0cd

guard var pointer = data.index(data.startIndex, offsetBy: offset, limitedBy: data.endIndex) else {