cpp-dns

C++ async DNS resolver using UDNS and Boost.

Requirements

Reasonably new versions of:

• C++17 compatible compiler
• CMake
• Boost
• UDNS

Quick command for Ubuntu users:

apt install build-essential cmake libboost-all-dev libudns-dev

Install

Use of Git submodule and CMake subdirectory is recommended.

mkdir cpp_modules && cd cpp_modules
git submodule add https://github.com/YukiWorkshop/cpp-dns

add_subdirectory(cpp_modules/cpp-dns)
include_directories(cpp_modules/cpp-dns)
target_link_libraries(your_project cpp-dns)

Usage

#include <cpp-dns.hpp>

using namespace YukiWorkshop;

Create a new resolver instance with default nameservers.

DNSResolver d(io_svc);

Or with custom nameservers.

DNSResolver d(io_svc, {"1.1.1.1", "8.8.8.8", "8.8.4.4"});

Get A records of google.com.

d.resolve_a4("google.com", [](int err, auto& addrs, auto& qname, auto& cname, uint ttl){
    if (!err) {
        std::cout << "Query: " << qname << "\n";
        std::cout << "CNAME: " << cname << "\n";
        std::cout << "TTL: " << ttl << "\n";

        for (auto &it : addrs) {
            std::cout << "A Record: " << it.to_string() << "\n";
        }
    }
});

Get matrix SRV records of riot.im.

d.resolve_srv("riot.im", "matrix", "tcp", [&](int err, auto& hosts, auto& qname, auto& cname, uint ttl){
    if (!err) {
        std::cout << "Query: " << qname << "\n";
        std::cout << "CNAME: " << cname << "\n";
        std::cout << "TTL: " << ttl << "\n";

        for (auto &it : hosts) {
            std::cout << "SRV Record: " << it.priority << " " << it.weight << " " << it.port << " "  << it.name << "\n";
        }
    }
});

See what's going wrong.

d.resolve_a4("kefpdngjvoeqjgp3rnskldv", [&](int err, auto& addrs, auto& qname, auto& cname, uint ttl){
    assert(err);
    std::cout << "Oops. " << DNSResolver::error_string(err) << "\n";
});

See Test.cpp for more examples.

Callback definitions are in DNSResolver.hpp.

Important notice: You need to prevent io_service from stopping. Otherwise you'll need to recreate DNSResolver since the UDP socket will get removed from io_service when it stops.

License

LGPL