73 lines
2.4 KiB
C#
73 lines
2.4 KiB
C#
using DNS.Client.RequestResolver;
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using DNS.Protocol;
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using DNS.Protocol.ResourceRecords;
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using Microsoft.Extensions.Logging;
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using Microsoft.Extensions.Options;
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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.Threading;
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using System.Threading.Tasks;
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namespace FastGithub.Dns
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{
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/// <summary>
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/// dns解析者
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/// </summary>
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sealed class RequestResolver : IRequestResolver
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{
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private readonly TimeSpan ttl = TimeSpan.FromMinutes(1d);
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private readonly IRequestResolver untrustedResolver;
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private readonly IOptionsMonitor<FastGithubOptions> options;
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private readonly ILogger<RequestResolver> logger;
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/// <summary>
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/// dns解析者
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/// </summary>
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/// <param name="options"></param>
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/// <param name="logger"></param>
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public RequestResolver(
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IOptionsMonitor<FastGithubOptions> options,
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ILogger<RequestResolver> logger)
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{
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this.options = options;
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this.logger = logger;
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this.untrustedResolver = new UdpRequestResolver(options.CurrentValue.GetTrustedDns());
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}
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/// <summary>
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/// 解析域名
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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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public async Task<IResponse> Resolve(IRequest request, CancellationToken cancellationToken = default)
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{
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var response = Response.FromRequest(request);
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if (request is not RemoteEndPointRequest remoteEndPointRequest)
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{
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return response;
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}
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var question = request.Questions.FirstOrDefault();
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if (question == null || question.Type != RecordType.A)
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{
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return response;
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}
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var domain = question.Name;
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if (this.options.CurrentValue.IsMatch(domain.ToString()) == true)
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{
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var localAddress = remoteEndPointRequest.GetLocalAddress() ?? IPAddress.Loopback;
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var record = new IPAddressResourceRecord(domain, localAddress, this.ttl);
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response.AnswerRecords.Add(record);
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this.logger.LogInformation($"[{domain}->{localAddress}]");
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return response;
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}
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return await this.untrustedResolver.Resolve(request, cancellationToken);
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}
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}
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}
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