65 lines
2.1 KiB
C#
65 lines
2.1 KiB
C#
using DNS.Client;
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using Microsoft.Extensions.Caching.Memory;
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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.Net.Http;
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using System.Threading;
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using System.Threading.Tasks;
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namespace FastGithub.ReverseProxy
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{
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/// <summary>
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/// github解析器
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/// </summary>
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sealed class GithubResolver
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{
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private readonly IMemoryCache memoryCache;
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private readonly IOptionsMonitor<FastGithubOptions> options;
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private readonly ILogger<GithubResolver> logger;
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/// <summary>
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/// github解析器
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/// </summary>
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/// <param name="options"></param>
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public GithubResolver(
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IMemoryCache memoryCache,
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IOptionsMonitor<FastGithubOptions> options,
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ILogger<GithubResolver> logger)
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{
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this.memoryCache = memoryCache;
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this.options = options;
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this.logger = logger;
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}
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/// <summary>
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/// 解析指定的域名
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/// </summary>
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/// <param name="domain"></param>
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/// <returns></returns>
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public async Task<IPAddress> ResolveAsync(string domain, CancellationToken cancellationToken)
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{
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// 缓存，避免做不必要的并发查询
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var key = $"domain:{domain}";
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var address = await this.memoryCache.GetOrCreateAsync(key, async e =>
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{
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e.SetAbsoluteExpiration(TimeSpan.FromMinutes(2d));
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var dnsClient = new DnsClient(this.options.CurrentValue.TrustedDns.ToIPEndPoint());
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var addresses = await dnsClient.Lookup(domain, DNS.Protocol.RecordType.A, cancellationToken);
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return addresses?.FirstOrDefault();
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});
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if (address == null)
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{
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var message = $"无法解析{domain}的ip";
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this.logger.LogWarning(message);
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throw new HttpRequestException(message);
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}
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this.logger.LogInformation($"[{domain}->{address}]");
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return address;
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}
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}
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}
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