67 lines
2.2 KiB
C#
67 lines
2.2 KiB
C#
using DNS.Client;
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using DNS.Client.RequestResolver;
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using DNS.Protocol;
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using DNS.Protocol.ResourceRecords;
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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.DomainResolve
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{
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/// <summary>
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/// DNS客户端
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/// </summary>
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sealed class DnsClient
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{
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private readonly IPEndPoint dns;
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private readonly IRequestResolver resolver;
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private readonly TimeSpan timeout = TimeSpan.FromSeconds(5d);
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/// <summary>
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/// DNS客户端
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/// </summary>
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/// <param name="dns"></param>
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/// <param name="forceTcp"></param>
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public DnsClient(IPEndPoint dns, bool forceTcp)
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{
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this.dns = dns;
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this.resolver = forceTcp
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? new TcpRequestResolver(dns)
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: new UdpRequestResolver(dns, new TcpRequestResolver(dns));
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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="domain"></param>
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/// <param name="cancellationToken"></param>
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/// <returns></returns>
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public async Task<IPAddress[]> LookupAsync(string domain, CancellationToken cancellationToken = default)
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{
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var request = new Request
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{
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RecursionDesired = true,
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OperationCode = OperationCode.Query
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};
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request.Questions.Add(new Question(new Domain(domain), RecordType.A));
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var clientRequest = new ClientRequest(this.resolver, request);
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using var timeoutTokenSource = new CancellationTokenSource(this.timeout);
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using var linkedTokenSource = CancellationTokenSource.CreateLinkedTokenSource(cancellationToken, timeoutTokenSource.Token);
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var response = await clientRequest.Resolve(linkedTokenSource.Token);
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return response.AnswerRecords.OfType<IPAddressResourceRecord>().Select(item => item.IPAddress).ToArray();
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}
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/// <summary>
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/// 转换为文本
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/// </summary>
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/// <returns></returns>
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public override string ToString()
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{
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return this.dns.ToString();
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}
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}
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}
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