389 lines
15 KiB
C#
389 lines
15 KiB
C#
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using System;
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using System.Collections.Generic;
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using System.Globalization;
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using System.Linq;
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using System.Net;
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using System.Net.Sockets;
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using System.Text.RegularExpressions;
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using System.Threading;
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using System.Threading.Tasks;
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using Ae.Dns.Protocol.Enums;
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using Ae.Dns.Protocol.Records;
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using PCL.Core.IO.Net.Dns;
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using PCL.Core.Logging;
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using PCL.Core.Utils;
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namespace PCL.Core.Minecraft;
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public static class ServerAddressResolver
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{
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public readonly record struct ResolvedServerAddress(string Host, string? Ip, int Port);
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// Minecraft Java 默认端口
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private const int DefaultPort = 25565;
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// Happy Eyeballs 族间启动间隔（降低首包时延）
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private static readonly TimeSpan _HappyEyeballsStagger = TimeSpan.FromMilliseconds(250);
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// 单次 TCP 连接超时
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private static readonly TimeSpan _ConnectTimeout = TimeSpan.FromSeconds(2.5);
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// [IPv6]:port 或 [IPv6]
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private static readonly Regex _BracketedIpv6 =
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new(@"^\[(?<ip>.+?)\](?::(?<port>\d{1,5}))?$", RegexOptions.Compiled | RegexOptions.CultureInvariant);
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// 纯端口（用于 host:port 末尾匹配）
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private static readonly Regex _TrailingPort =
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new(@":(?<port>\d{1,5})$", RegexOptions.Compiled | RegexOptions.CultureInvariant);
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public static async Task<ResolvedServerAddress> GetResolvedServerAddressAsync(string address, CancellationToken cancelToken = default)
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{
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if (string.IsNullOrWhiteSpace(address))
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throw new ArgumentException("服务器地址不能为空", nameof(address));
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// 规范化：去除 scheme、空白、尾随斜杠
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address = _NormalizeInput(address);
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// 1) 解析出 host/ip 与端口（若端口未提供则为 null）
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var (hostOrIp, portOpt) = _ParseHostAndPort(address);
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// 2) 显式端口 => 禁止 SRV，直接解析 IP 并尝试连接
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if (portOpt is { } explicitPort)
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{
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_ValidatePort(explicitPort);
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LogWrapper.Info($"使用显式端口，跳过 SRV：{hostOrIp}:{explicitPort}");
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var target = await _ResolveReachableAsync(hostOrIp, explicitPort, cancelToken).ConfigureAwait(false);
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if (target is not null)
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return new ResolvedServerAddress(hostOrIp, target.Value.Ip, target.Value.Port);
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// 回退策略：无法连接则仍返回解析到的首个 IP
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var fallbackIp = await _ResolveFirstIpAsync(hostOrIp, cancelToken).ConfigureAwait(false);
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return new ResolvedServerAddress(hostOrIp, fallbackIp, explicitPort);
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}
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// 3) 未指定端口
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// 3.1 纯 IP（IPv4/IPv6）=> 直接使用默认端口
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if (IPAddress.TryParse(hostOrIp, out _))
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{
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var target = await _ResolveReachableAsync(hostOrIp, DefaultPort, cancelToken).ConfigureAwait(false);
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if (target is not null)
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return new ResolvedServerAddress(hostOrIp, target.Value.Ip, target.Value.Port);
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return new ResolvedServerAddress(hostOrIp, hostOrIp, DefaultPort);
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}
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// 3.2 域名 => 先尝试 SRV（_minecraft._tcp.），成功则按 SRV 顺序与加权尝试
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var idnHost = _ToAsciiIdn(hostOrIp);
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var srvOrdered = await _QuerySrvOrderedAsync(idnHost, cancelToken).ConfigureAwait(false);
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if (srvOrdered.Count > 0)
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{
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LogWrapper.Info($"SRV 记录可用（{srvOrdered.Count}）: _minecraft._tcp.{idnHost}");
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foreach (var srv in srvOrdered)
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{
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var targetHost = _TrimTrailingDot(srv.Target);
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var port = srv.Port;
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var reachable = await _ResolveReachableAsync(targetHost, port, cancelToken).ConfigureAwait(false);
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if (reachable is not null)
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{
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LogWrapper.Info($"SRV 命中：{targetHost}:{port} -> {reachable.Value.Ip}:{port}");
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return new ResolvedServerAddress(idnHost, reachable.Value.Ip, reachable.Value.Port);
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}
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}
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// SRV 全部不可达则回退到 SRV 第一条的解析 IP 或域名默认端口
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var first = srvOrdered[0];
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var firstIp = await _ResolveFirstIpAsync(_TrimTrailingDot(first.Target), cancelToken).ConfigureAwait(false);
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if (!string.IsNullOrEmpty(firstIp)) return new ResolvedServerAddress(idnHost, firstIp, first.Port);
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}
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else
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{
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LogWrapper.Info($"无 SRV 记录或查询失败，回退默认端口：{idnHost}:{DefaultPort}");
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}
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// 3.3 最终回退：域名 + 默认端口
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var ip = await _ResolveFirstIpAsync(idnHost, cancelToken).ConfigureAwait(false);
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return new ResolvedServerAddress(idnHost, ip, DefaultPort);
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}
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// 规范化地址输入：去掉 scheme、空白、尾随 '/'
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private static string _NormalizeInput(string input)
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{
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var s = input.Trim();
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// 去掉任意 scheme:// 前缀（例如 http://、https://、minecraft://）
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var schemeIdx = s.IndexOf("://", StringComparison.Ordinal);
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if (schemeIdx > 0)
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s = s[(schemeIdx + 3)..];
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// 去掉尾随的 '/'
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while (s.EndsWith("/", StringComparison.Ordinal))
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s = s[..^1];
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return s;
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}
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private static void _ValidatePort(int port)
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{
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if (port is < 1 or > 65535)
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throw new FormatException($"无效的端口：{port}");
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}
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private static string _ToAsciiIdn(string host)
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{
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try
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{
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// 处理国际化域名
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var idn = new IdnMapping();
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// 允许末尾点号（FQDN）
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var h = _TrimTrailingDot(host);
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return idn.GetAscii(h) + (host.EndsWith(".", StringComparison.Ordinal) ? "." : "");
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}
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catch
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{
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// 无法转换时返回原值，交给后续 DNS 解析处理
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return host;
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}
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}
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private static string _TrimTrailingDot(string host)
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=> host.EndsWith(".", StringComparison.Ordinal) ? host[..^1] : host;
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private static (string HostOrIp, int? Port) _ParseHostAndPort(string input)
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{
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// 1) [IPv6] 或 [IPv6]:port
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var m = _BracketedIpv6.Match(input);
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if (m.Success)
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{
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var ip = m.Groups["ip"].Value;
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if (!IPAddress.TryParse(ip, out _))
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throw new FormatException("无效的 IPv6 地址格式");
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var portGroup = m.Groups["port"];
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if (portGroup.Success)
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{
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var port = int.Parse(portGroup.Value, CultureInfo.InvariantCulture);
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_ValidatePort(port);
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return (ip, port);
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}
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return (ip, null);
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}
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// 2) 试图解析为纯 IP（IPv4 或 IPv6 无端口）
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if (IPAddress.TryParse(input, out _))
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return (input, null);
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// 3) host:port（仅在末尾存在且为纯数字端口时成立）
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var pm = _TrailingPort.Match(input);
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if (pm.Success)
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{
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// 防止误把 IPv6 当作 host:port（IPv6 必须用中括号携带端口）
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// 此处 input 中若包含多个 ':' 则极可能是 IPv6 而非 host:port
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var colonCount = input.Count(c => c == ':');
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if (colonCount == 1)
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{
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var port = int.Parse(pm.Groups["port"].Value, CultureInfo.InvariantCulture);
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_ValidatePort(port);
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var host = input[..^pm.Value.Length];
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if (string.IsNullOrWhiteSpace(host))
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throw new FormatException("无效的主机名");
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return (host, port);
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}
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}
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// 4) 其余情况按“域名（无端口）”处理
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return (input, null);
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}
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// ===== SRV 查询与排序（RFC 2782） =====
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private sealed record SrvRecord(int Priority, int Weight, int Port, string Target);
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private static async Task<List<SrvRecord>> _QuerySrvOrderedAsync(string domain, CancellationToken ct)
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{
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try
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{
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var name = $"_minecraft._tcp.{_TrimTrailingDot(domain)}";
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LogWrapper.Info($"尝试 SRV 查询：{name}");
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// NDnsQuery.GetSrvRecords 返回 string 列表，为兼容不同实现，这里进行鲁棒解析
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var raw = await DnsQuery.Instance.QueryAsync(name, DnsQueryType.SRV, ct);
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if (raw is null || raw.Answers.Count == 0) return [];
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List<SrvRecord> parsed = [];
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foreach (var answer in raw.Answers)
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{
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if (answer.Resource is not DnsUnknownResource dnsRaw) return [];
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var srcRecord = new DnsSrvResource();
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var offset = 0;
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srcRecord.ReadBytes(dnsRaw.Raw, ref offset, dnsRaw.Raw.Length);
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parsed.Add(new SrvRecord(srcRecord.Priority, srcRecord.Weight, srcRecord.Port, srcRecord.Target));
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}
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// 过滤 target 为 "."（表示服务不可用）
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parsed.RemoveAll(p => p.Target == ".");
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if (parsed.Count == 0)
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return [];
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// RFC 2782：按 priority 升序；相同 priority 内按权重加权随机选择顺序
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var ordered = new List<SrvRecord>(parsed.Count);
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foreach (var group in parsed.GroupBy(p => p.Priority).OrderBy(g => g.Key))
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{
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var pool = group.ToList();
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while (pool.Count > 0)
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{
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var next = _PopByWeight(pool);
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ordered.Add(next);
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}
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}
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return ordered;
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}
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catch (SocketException ex)
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{
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LogWrapper.Warn(ex, "SRV 查询失败（网络错误）");
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return [];
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}
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catch (Exception ex)
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{
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LogWrapper.Warn(ex, "SRV 查询异常");
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return [];
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}
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}
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private static SrvRecord _PopByWeight(List<SrvRecord> pool)
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{
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// RFC 2782 加权随机：在组内以 weight 为权重抽取
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var total = pool.Sum(p => p.Weight);
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if (total <= 0)
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{
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// 无权重时等概率
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var i = RandomUtils.NextInt(0, pool.Count - 1);
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var chosen = pool[i];
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pool.RemoveAt(i);
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return chosen;
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}
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var r = RandomUtils.NextInt(1, total); // (1..total)
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var sum = 0;
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for (var i = 0; i < pool.Count; i++)
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{
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sum += pool[i].Weight;
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if (sum >= r)
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{
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var chosen = pool[i];
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pool.RemoveAt(i);
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return chosen;
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}
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}
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// 理论不可达，兜底返回末尾
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var last = pool[^1];
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pool.RemoveAt(pool.Count - 1);
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return last;
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}
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// ===== DNS 与连接可达性 =====
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private static async Task<(string Ip, int Port)?> _ResolveReachableAsync(string hostOrIp, int port, CancellationToken ct)
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{
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try
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{
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// 已是字面量 IP
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if (IPAddress.TryParse(hostOrIp, out var ipLiteral))
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{
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var result = await _ConnectOneAsync(ipLiteral, port, ct).ConfigureAwait(false);
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if (result.ok) return (ipLiteral.ToString(), port);
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return null;
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}
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var addresses = await Dns.GetHostAddressesAsync(_TrimTrailingDot(hostOrIp), ct).ConfigureAwait(false);
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if (addresses.Length == 0)
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return null;
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// Happy Eyeballs：分组（IPv6、IPv4），按组分阶段并行连接，取首个成功
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var v6 = addresses.Where(a => a.AddressFamily == AddressFamily.InterNetworkV6).ToArray();
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var v4 = addresses.Where(a => a.AddressFamily == AddressFamily.InterNetwork).ToArray();
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// 第一阶段：IPv6
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var winner = await _ConnectAnyAsync(v6, port, TimeSpan.Zero, ct).ConfigureAwait(false);
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if (winner is not null)
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return (winner, port);
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// 第二阶段：IPv4（稍作延迟以避免同时轰炸）
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winner = await _ConnectAnyAsync(v4, port, _HappyEyeballsStagger, ct).ConfigureAwait(false);
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if (winner is not null)
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return (winner, port);
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return null;
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}
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catch (Exception ex) when (ex is not OperationCanceledException)
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{
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LogWrapper.Warn(ex, $"解析或连接失败：{hostOrIp}:{port}");
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return null;
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}
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}
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private static async Task<string?> _ResolveFirstIpAsync(string hostOrIp, CancellationToken ct)
|
|||
|
|
{
|
|||
|
|
try
|
|||
|
|
{
|
|||
|
|
if (IPAddress.TryParse(hostOrIp, out var ip))
|
|||
|
|
return ip.ToString();
|
|||
|
|
|
|||
|
|
var addresses = await Dns.GetHostAddressesAsync(_TrimTrailingDot(hostOrIp), ct).ConfigureAwait(false);
|
|||
|
|
var chosen = addresses.FirstOrDefault(a => a.AddressFamily == AddressFamily.InterNetworkV6)
|
|||
|
|
?? addresses.FirstOrDefault(a => a.AddressFamily == AddressFamily.InterNetwork);
|
|||
|
|
return chosen?.ToString();
|
|||
|
|
}
|
|||
|
|
catch (Exception ex) when (ex is not OperationCanceledException)
|
|||
|
|
{
|
|||
|
|
LogWrapper.Warn(ex, $"DNS 解析失败：{hostOrIp}");
|
|||
|
|
return null;
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private static async Task<string?> _ConnectAnyAsync(IReadOnlyList<IPAddress> addrs, int port, TimeSpan delay, CancellationToken ct)
|
|||
|
|
{
|
|||
|
|
if (addrs.Count == 0) return null;
|
|||
|
|
if (delay > TimeSpan.Zero)
|
|||
|
|
await Task.Delay(delay, ct).ConfigureAwait(false);
|
|||
|
|
|
|||
|
|
using var cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
|
|||
|
|
var tasks = new List<Task<(bool ok, string ip)>>(addrs.Count);
|
|||
|
|
tasks.AddRange(addrs.Select(ip => _ConnectOneAsync(ip, port, cts.Token)));
|
|||
|
|
|
|||
|
|
while (tasks.Count > 0)
|
|||
|
|
{
|
|||
|
|
var done = await Task.WhenAny(tasks).ConfigureAwait(false);
|
|||
|
|
tasks.Remove(done);
|
|||
|
|
var (ok, ip) = await done.ConfigureAwait(false);
|
|||
|
|
if (!ok) continue;
|
|||
|
|
// 取消其余连接尝试
|
|||
|
|
try { await cts.CancelAsync().ConfigureAwait(false); } catch { /* ignore */ }
|
|||
|
|
return ip;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
return null;
|
|||
|
|
}
|
|||
|
|
|
|||
|
|
private static async Task<(bool ok, string ip)> _ConnectOneAsync(IPAddress ip, int port, CancellationToken ct)
|
|||
|
|
{
|
|||
|
|
try
|
|||
|
|
{
|
|||
|
|
using var sock = new Socket(ip.AddressFamily, SocketType.Stream, ProtocolType.Tcp);
|
|||
|
|
sock.NoDelay = true;
|
|||
|
|
|
|||
|
|
using var timeoutCts = new CancellationTokenSource(_ConnectTimeout);
|
|||
|
|
using var linked = CancellationTokenSource.CreateLinkedTokenSource(ct, timeoutCts.Token);
|
|||
|
|
#if NET8_0_OR_GREATER
|
|||
|
|
await sock.ConnectAsync(new IPEndPoint(ip, port), linked.Token).ConfigureAwait(false);
|
|||
|
|
#else
|
|||
|
|
await sock.ConnectAsync(new IPEndPoint(ip, port)).WaitAsync(ConnectTimeout, linked.Token).ConfigureAwait(false);
|
|||
|
|
#endif
|
|||
|
|
return (true, ip.ToString());
|
|||
|
|
}
|
|||
|
|
catch
|
|||
|
|
{
|
|||
|
|
return (false, ip.ToString());
|
|||
|
|
}
|
|||
|
|
}
|
|||
|
|
}
|