Reproduction of LLM-over-DNS in C# 10

llm-app.cs

#:package ARSoft.Tools.Net@3.6.1
#:package LLMTornado@3.7.25

using ARSoft.Tools.Net;
using ARSoft.Tools.Net.Dns;
using LlmTornado.Code;
using LlmTornado;
using LlmTornado.Chat;

(string EnvKey, LLmProviders Provider)[] Providers = [
    ("GOOGLE_API_KEY", LLmProviders.Google),
    ("OAI_API_KEY", LLmProviders.OpenAi),
    ("ANTHROPIC_API_KEY", LLmProviders.Anthropic),
    ("OPENROUTER_API_KEY", LLmProviders.OpenRouter),
    ("COHERE_API_KEY", LLmProviders.Cohere),
    ("GROQ_API_KEY", LLmProviders.Groq),
    ("DEEPSEEK_API_KEY", LLmProviders.DeepSeek),
    ("MISTRAL_API_KEY", LLmProviders.Mistral),
    ("XAI_API_KEY", LLmProviders.XAi),
    ("PERPLEXITY_API_KEY", LLmProviders.Perplexity)
];

// Get the model
string? model = Environment.GetEnvironmentVariable("LLM_MODEL");
if (string.IsNullOrWhiteSpace(model))
    throw new ArgumentException("LLM_MODEL configuration is required.");

// Get the configured provider (Will throw error if not found)
var provider = Providers.First(p => !string.IsNullOrWhiteSpace(Environment.GetEnvironmentVariable(p.EnvKey)));

var api = new TornadoApi(Environment.GetEnvironmentVariable(provider.EnvKey)!, provider.Provider);

var server = new DnsServer();
server.QueryReceived += async (object sender, QueryReceivedEventArgs e) => {
    try {
        var query = e.Query as DnsMessage ?? throw new ArgumentException("Query is not a valid DNS message.");
        if (query.Questions.Count != 1 || query.Questions[0].RecordType != RecordType.Txt)
            return;

        var response = query.CreateResponseInstance();
        e.Response = response;

        var domain = query.Questions[0].Name;
        var llmResult = await api.Chat.CreateConversation(model)
                .AppendAssistantMessage("You are a helpful assistant who responds very very concisely.")
                .AppendUserInput(domain.ToString())
                .GetResponseRich();

        // Break it up into chunks of 250 chars (TODO: handle bytes)
        int offset = 0;
        while (offset < llmResult.Text.Length) {
            response.AnswerRecords.Add(new TxtRecord(domain, 3600, llmResult.Text[offset..Math.Min(llmResult.Text.Length, offset + 250)]));
            offset += 250;
        }
        response.ReturnCode = ReturnCode.NoError;
    }
    catch (Exception ex) {
        Console.WriteLine("Error processing DNS query: " + ex.Message);
    }
};

server.Start();
Console.WriteLine("DNS server started on port 53");
try {
    await Task.Delay(Timeout.Infinite, CancellationToken.None);
} 
finally {
    server.Stop();
    Console.WriteLine("DNS server stopped");
}