69 lines
2.1 KiB
C#
69 lines
2.1 KiB
C#
using DNS.Client;
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using Microsoft.Extensions.DependencyInjection;
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using System;
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using System.Linq;
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using System.Net;
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using System.Net.Http;
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using System.Threading;
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using System.Threading.Tasks;
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namespace FastGithub.Scanner
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{
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/// <summary>
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/// 由本程序提值的dns的httpHandler
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/// </summary>
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[Service(ServiceLifetime.Transient)]
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sealed class LoopbackDnsHttpHandler : DelegatingHandler
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{
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/// <summary>
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/// 本程序的dns
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/// </summary>
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private static readonly DnsClient dnsClient = new(IPAddress.Loopback);
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/// <summary>
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/// 发送消息
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/// </summary>
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/// <param name="request"></param>
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/// <param name="cancellationToken"></param>
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/// <returns></returns>
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protected override async Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
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{
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var uri = request.RequestUri;
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if (uri != null && uri.HostNameType == UriHostNameType.Dns)
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{
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var address = await LookupAsync(uri.Host);
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if (address != null)
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{
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var builder = new UriBuilder(uri)
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{
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Host = address.ToString()
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};
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request.RequestUri = builder.Uri;
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request.Headers.Host = uri.Host;
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}
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}
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return await base.SendAsync(request, cancellationToken);
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}
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/// <summary>
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/// dns解析ip
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/// </summary>
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/// <param name="host"></param>
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/// <returns></returns>
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private static async Task<IPAddress?> LookupAsync(string host)
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{
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try
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{
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using var cancellationTokenSource = new CancellationTokenSource(TimeSpan.FromMilliseconds(500d));
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var addresses = await dnsClient.Lookup(host, cancellationToken: cancellationTokenSource.Token);
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return addresses.FirstOrDefault();
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}
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catch (Exception)
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{
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return default;
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}
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}
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}
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}
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