Durian.cr - Domain Name System Resolver

Description

• Because Crystal Domain Name Resolver uses C.getaddrinfo, It seems to have serious problems.
  • This may cause the program to Freeze, so I created this repository.
• Of course, Crystal official is always busy, it will not help you solve these problems.
  • Thanks to rdp for the help, this made me sure that the problem was caused by C.getaddrinfo.
• Then I discovered the CrDNS repository, but it too broken, so I gave up the idea.
  • I started looking at many documents and started researching how to build a DNS resolver.
  • It took me some time to make it, it's not troublesome, it's not easy.
• That's it, Thanks for using, If you encounter any problems, please let me know.

Features

• If sending fails, it will try to resend through the next DNS server.
• It supports Querying / Receiving multiple DNS record Types.
  • AAAA
  • A
  • NS
  • PTR
  • SOA
  • TXT
  • MX
  • CNAME
  • DNAME
  • SRV
• It supports TCP and UDP protocols DNS server.
• It does not contain any C.getaddrinfo.
• It supports simple DNS caching (non-LRUCache).
  • (tapCount + updatedAt) custom Cache.
• You can send / receive packets via Resolver.
  • or you can process packets via Packet.from_io, Packet.to_io.
• ...

Tips

• If the connection fails or there is no response packet, it will try to use the next server.
• C.getaddrinfo is incompatible with green threads, It may cause your program to pause.
  • C.getaddrinfo is too bad, you should not use it in green thread.
  • (libuv uv_getaddrinfo, libevent evdns_getaddrinfo) is too complicated, you may encounter many problems.

Next

• Support Alias & Mapping and Special DNS Server.
• Support response packet to_io operation.
• More exception handling.
• Support DNS server features.
• Better performance, Better DNS cache.
• Supported DNS over TLS (DoT) feature.

Usage

• Client | Http - Testing DNS resolution for IP availability.

require "durian"

servers = [] of Durian::Resolver::Server
servers << Durian::Resolver::Server.new ipAddress: Socket::IPAddress.new("8.8.8.8", 53_i32), protocol: Durian::Protocol::UDP
servers << Durian::Resolver::Server.new ipAddress: Socket::IPAddress.new("1.1.1.1", 53_i32), protocol: Durian::Protocol::UDP

buffer = uninitialized UInt8[4096_i32]
resolver = Durian::Resolver.new servers
resolver.ip_cache = Durian::Cache::IPAddress.new

begin
  socket = Durian::TCPSocket.connect "www.example.com", 80_i32, resolver, 5_i32
  socket.read_timeout = 5_i32
  socket.write_timeout = 5_i32
rescue
  abort "Connect Failed"
end

begin
  socket << "GET / HTTP/1.1\r\nHost: www.example.com\r\nConnection: close\r\n\r\n"
rescue
  abort "Write Failed"
end

begin
  length = socket.read buffer.to_slice
rescue
  abort "Read Failed"
end

STDOUT.puts [length, String.new buffer.to_slice[0_i32, length]]

• Client | Query - A similar React Proc usage.

require "durian"

servers = [] of Durian::Resolver::Server
servers << Durian::Resolver::Server.new ipAddress: Socket::IPAddress.new("8.8.8.8", 53_i32), protocol: Durian::Protocol::UDP
servers << Durian::Resolver::Server.new ipAddress: Socket::IPAddress.new("1.1.1.1", 53_i32), protocol: Durian::Protocol::UDP

resolver = Durian::Resolver.new servers
resolver.record_cache = Durian::Cache::Record.new

resolver.resolve "google.com", [Durian::RecordFlag::A, Durian::RecordFlag::AAAA] do |response|
  STDOUT.puts [:Google, Time.utc, response]
end

resolver.resolve "twitter.com", Durian::RecordFlag::SOA do |response|
  STDOUT.puts [:Twitter, Time.utc, response]
end

resolver.resolve "facebook.com", [Durian::RecordFlag::A, Durian::RecordFlag::AAAA] do |response|
  STDOUT.puts [:FaceBook, Time.utc, response]
end

resolver.resolve "twitter.com", Durian::RecordFlag::SOA do |response|
  STDOUT.puts [:Twitter, Time.utc, response]
end

resolver.run

• Client | Packet - from_io, to_io usage.

require "durian"

buffer = uninitialized UInt8[4096_i32]

request = Durian::Packet.new Durian::Protocol::UDP, Durian::Packet::QRFlag::Query
request.add_query "www.example.com", Durian::RecordFlag::A

_request = IO::Memory.new request.to_slice
STDOUT.puts [:Request, Durian::Packet.from_io Durian::Protocol::UDP, _request]

udp_socket = UDPSocket.new
udp_socket.connect Socket::IPAddress.new "8.8.8.8", 53_i32
udp_socket.send _request.to_slice
length, ip_address = udp_socket.receive buffer.to_slice

_response = IO::Memory.new buffer.to_slice[0_i32, length]
STDOUT.puts [:Response, Durian::Packet.from_io Durian::Protocol::UDP, _response]

Used as Shard

Add this to your application's shard.yml:

dependencies:
  durian:
    github: 636f7374/durian.cr

Installation

$ git clone https://github.com/636f7374/durian.cr.git

Development

$ make test

References

• StackOverflow | How to convert a string or integer to binary in Ruby?
• StackOverflow | Requesting A and AAAA records in single DNS query
• StackOverflow | Example of DNS Compression Pointer Offset > than 12 bytes
• StackOverflow | why libuv do DNS request by multiple thread
• Official | DNS_HEADER structure
• Official | The Saga of Concurrent DNS in Python, and the Defeat of the Wicked Mutex Troll
• Official | Help understanding DNS packet data
• Official | Ietf - RFC 1035
• Official | Docs.rs::hyper_trust_dns_connector
• Official | libuv provides asynchronous variants of getaddrinfo and getnameinfo
• Blogs | Adventures in Rust: Futures and Tokio
• Blogs | Cocoa: Asynchronous Host name lookups
• Blogs | Using DNS with Libevent: high and low-level functionality
• Blogs | The problem with libresolv
• Blogs | The problem with getaddrinfo
• Blogs | What does getaddrinfo do?
• Blogs | A warm welcome to DNS
• Document | DNS Query Message Format
• Docuemnt | Protocol and Format
• Document | Binary Numbers
• Document | DNS Message Header and Question Section Format
• Document | DNS Name Notation and Message Compression Technique
• Github Gist | DNS Query Code in C with linux sockets
• Github Gist | getaddrinfo.strace
• Source Code | posix/getaddrinfo.c
• Source Code | DNS header for C | 0x00sec
• ...

Related

• #8480 | blocking call in one fiber can cause IO timeouts in others
• #4816 | Add Resolv class to standard library
• #2660 | Fix/Implement own DNS resolver
• #4236 | Configurable DNS resolvers
• #2829 | DNS threaded resolver
• #2745 | Don't use libevent's getaddrinfo, use C's getaddrinfo
• #8376 | Some TCPSocket connections will cause HTTP::Server accept (freeze | blocking | hangs | waiting)?
• ...

Credit

• _Icon::Wanicon/Fruits
• _Icon::Freepik/GraphicDesign

Contributors

Name	Creator	Maintainer	Contributor
636f7374	√	√
rdp			√
teknomunk			√
ilmanzo			√
yunixon			√
z64			√

License

• MIT License