measurement: name the kinds by protocol and action, add the http_request kind and QUIC settings

backend/shared/MoShiro.Protocol/Tasks/TargetHost.cs

@@ -0,0 +1,104 @@
+using System.Globalization;
+using System.Net;
+
+namespace MoShiro.Protocol;
+
+/// <summary>
+/// 单个 Agent 任务的目标：<c>http</c> 是 <c>http(s)://主机[:端口][/路径]</c>，其余 Kind 是 <c>主机[:端口]</c>（IP 或域名，IPv6 带端口时用方括号）。
+/// Backend 只检查格式，不做 DNS 解析；解析在 Agent 上进行，每个解析出的地址都要在 <c>allowed_target_cidrs</c> 里。
+/// </summary>
+public static class TargetHost
+{
+    public const string HttpKind = "http_request";
+
+    /// <summary>解析目标；<paramref name="port"/> 为 0 表示没有写端口，<paramref name="url"/> 只在 http(s) URL 时有值。</summary>
+    public static bool TryParse(string? target, out string host, out int port, out Uri? url)
+    {
+        host = "";
+        port = 0;
+        url = null;
+        if (string.IsNullOrWhiteSpace(target) || target.Length > 2048 || target.Any(char.IsWhiteSpace))
+        {
+            return false;
+        }
+
+        if (target.Contains("://", StringComparison.Ordinal))
+        {
+            if (!Uri.TryCreate(target, UriKind.Absolute, out Uri? uri) || uri.Scheme is not ("http" or "https") || uri.UserInfo.Length > 0 || !ValidHost(uri.IdnHost))
+            {
+                return false;
+            }
+
+            url = uri;
+            host = uri.IdnHost.Trim('[', ']');
+            port = uri.IsDefaultPort ? 0 : uri.Port;
+            return true;
+        }
+
+        // IPAddress.TryParse 会把「[v6]:端口」的端口丢掉，带方括号的先按端点解析
+        if (!target.StartsWith('[') && IPAddress.TryParse(target, out IPAddress? ip))
+        {
+            host = ip.ToString();
+            return true;
+        }
+
+        if (IPEndPoint.TryParse(target, out IPEndPoint? endpoint))
+        {
+            if (endpoint.Port is 0)
+            {
+                return false;
+            }
+
+            host = endpoint.Address.ToString();
+            port = endpoint.Port;
+            return true;
+        }
+
+        int colon = target.LastIndexOf(':');
+        string name = colon < 0 ? target : target[..colon];
+        if (colon >= 0 && (!int.TryParse(target.AsSpan(colon + 1), NumberStyles.None, CultureInfo.InvariantCulture, out port) || port is < 1 or > 65535))
+        {
+            return false;
+        }
+
+        if (!ValidHost(name))
+        {
+            return false;
+        }
+
+        host = name.ToLowerInvariant();
+        return true;
+    }
+
+    /// <summary>按 Kind 检查并规范化：<c>http</c> 必须是 http(s) URL，其余 Kind 必须是主机[:端口]；不合格返回 null。</summary>
+    public static string? Normalize(string kindId, string? target)
+    {
+        if (!TryParse(target, out string host, out int port, out Uri? url) || (url is not null) != (kindId == HttpKind))
+        {
+            return null;
+        }
+
+        if (url is not null)
+        {
+            return url.AbsoluteUri;
+        }
+
+        string shown = IPAddress.TryParse(host, out IPAddress? ip) && ip.AddressFamily == System.Net.Sockets.AddressFamily.InterNetworkV6 && port != 0 ? "[" + host + "]" : host;
+        return port == 0 ? host : shown + ":" + port.ToString(CultureInfo.InvariantCulture);
+    }
+
+    private static bool ValidHost(string name)
+    {
+        if (IPAddress.TryParse(name.Trim('[', ']'), out _))
+        {
+            return true;
+        }
+
+        if (name.Length is 0 or > 253 || name[^1] == '-' || name[0] is '-' or '.')
+        {
+            return false;
+        }
+
+        return name.TrimEnd('.').Split('.').All(label => label.Length is > 0 and <= 63 && label.All(c => char.IsAsciiLetterOrDigit(c) || c == '-'));
+    }
+}