c# - 是否可以在 C# 的 HttpClient 中设置自定义 DNS 解析器

Question

我到底想要什么:

public static CustomDnsResolver : Dns 
{
   .....
}

public static void Main(string[] args) 
{
    var httpClient = new HttpClient();
    httpClient.Dns(new CustomDnsResolver());
}

基本上我只想在 HttpClient 中使用我的自定义 DNS 解析器而不是系统默认值，有什么方法可以实现吗？

Answer 1

您拥有的用例正是 Microsoft 构建 HttpClient 堆栈的原因。它允许您在 HttpMessageHandler 的帮助下将业务逻辑放在分层类中类(class)。您可以在 ms docs 中找到一些样本或 visualstudiomagazine

void Main()
{
    var dnsHandler = new DnsHandler(new CustomDnsResolver());
    var client = new HttpClient(dnsHandler);
    var html = client.GetStringAsync("http://google.com").Result;
}

public class DnsHandler : HttpClientHandler
{
    private readonly CustomDnsResolver _dnsResolver;

    public DnsHandler(CustomDnsResolver dnsResolver)
    {
        _dnsResolver = dnsResolver;
    }

    protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
    {
        var host = request.RequestUri.Host;
        var ip = _dnsResolver.Resolve(host);

        var builder = new UriBuilder(request.RequestUri);
        builder.Host = ip;

        request.RequestUri = builder.Uri;

        return base.SendAsync(request, cancellationToken);
    }
}

public class CustomDnsResolver
{
    public string Resolve(string host)
    {
        return "127.0.0.1";
    }
}