feat: 文传易匿名临时文件传输站初始版本

- 后端 .NET 8 + FreeSql + 阿里云 OSS，支持共享/私密/标签三种文件模式 - 前端 Vue3 + Vite + TDesign，上传/取件/管理三页 - 取件码/二维码/海报合成（含保存二维码为图片） - deploy/ 部署文档与一键 FTP 发布脚本 - appsettings.json 含真实凭据，已 gitignore 不入库
2026-08-24 00:03:28 +08:00
commit 1bfc72f9cb
40 changed files with 6849 additions and 0 deletions
@@ -0,0 +1,108 @@
+using System.Text.RegularExpressions;
+using WenChuanyi.Api.Models;
+
+namespace WenChuanyi.Api.Services;
+
+/// <summary>业务规则共享静态工具：密码/标签校验、模式判定、预览分类</summary>
+public static class FileRules
+{
+    public const long MaxFileBytes = 200L * 1024 * 1024;   // 200MB
+    public const long MaxTextPreview = 2L * 1024 * 1024;   // 文本预览 2MB
+    public const long MaxPdfImagePreview = 30L * 1024 * 1024; // PDF/图片预览 30MB
+
+    /// <summary>清洗文件名：去除 Windows 非法字符/控制字符、首尾空格与点、保留名与超长限制，防止存储路径注入</summary>
+    public static string SanitizeFileName(string? name)
+    {
+        if (string.IsNullOrWhiteSpace(name)) return "未命名";
+        var dot = name.LastIndexOf('.');
+        var ext = dot >= 0 ? name[(dot + 1)..] : "";
+        var baseName = dot >= 0 ? name[..dot] : name;
+
+        var cleanBase = new string(baseName
+            .Where(c => c >= 32 && c != 127 && c != '<' && c != '>' && c != ':' && c != '"'
+                && c != '/' && c != '\\' && c != '|' && c != '?' && c != '*')
+            .ToArray()).Trim().TrimEnd('.', ' ');
+
+        var result = string.IsNullOrEmpty(cleanBase) ? "未命名" : cleanBase;
+
+        // Windows 保留设备名：CON PRN AUX NUL COM1-9 LPT1-9（含扩展名也禁止）
+        var upperBase = result.Split('.')[0].ToUpperInvariant();
+        if (upperBase is "CON" or "PRN" or "AUX" or "NUL"
+            || Regex.IsMatch(upperBase, @"^COM[1-9]$") || Regex.IsMatch(upperBase, @"^LPT[1-9]$"))
+        {
+            result = "_" + result;
+        }
+
+        // 长度限制（保留扩展名，主体最长 180 字符）
+        if (result.Length > 180) result = result[..180];
+
+        // 扩展名仅保留字母/数字/点，最长 10 字符
+        var extRaw = new string(ext.Where(c => char.IsLetterOrDigit(c) || c == '.').ToArray()).TrimStart('.');
+        var cleanExt = extRaw.Length > 0 ? "." + (extRaw.Length > 10 ? extRaw[..10] : extRaw) : "";
+
+        return result + cleanExt;
+    }
+
+    /// <summary>校验密码（4-12 位），null 表示通过</summary>
+    public static string? ValidatePassword(string? pwd)
+    {
+        if (string.IsNullOrEmpty(pwd)) return null;
+        if (pwd.Length < 4 || pwd.Length > 12)
+        {
+            return "密码长度须为 4-12 位";
+        }
+        return null;
+    }
+
+    /// <summary>校验标签：仅英文+数字；纯数字须 &gt;8 位；含英文须 &gt;4 位；null 表示通过</summary>
+    public static string? ValidateTag(string? tag)
+    {
+        if (string.IsNullOrEmpty(tag)) return null;
+        if (!Regex.IsMatch(tag, "^[A-Za-z0-9]+$"))
+        {
+            return "标签仅允许英文与数字，不能包含符号或空格";
+        }
+        if (Regex.IsMatch(tag, "^[0-9]+$"))
+        {
+            if (tag.Length <= 8)
+            {
+                return "纯数字标签须超过 8 位（建议使用 11 位手机号码）";
+            }
+        }
+        else if (tag.Length <= 4)
+        {
+            return "含英文字母的标签须超过 4 位";
+        }
+        return null;
+    }
+
+    /// <summary>模式判定：有密码→private；仅标签→tagged；否则 standard</summary>
+    public static string ResolveFileType(bool hasPassword, bool hasTag)
+        => hasPassword ? "private" : hasTag ? "tagged" : "standard";
+
+    /// <summary>取件码位数：私密 6 位，其余 8 位</summary>
+    public static int PickCodeLength(string fileType) => fileType == "private" ? 6 : 8;
+
+    /// <summary>剩余有效期文本</summary>
+    public static string ExpireText(FileItem f)
+    {
+        if (f.IsPermanent || f.ExpiresAt == null) return "永久";
+        var remain = f.ExpiresAt.Value - DateTime.Now;
+        if (remain <= TimeSpan.Zero) return "已过期";
+        if (remain.TotalDays >= 1) return $"{(int)remain.TotalDays} 天";
+        if (remain.TotalHours >= 1) return $"{(int)remain.TotalHours} 小时";
+        return $"{(int)Math.Max(1, remain.TotalMinutes)} 分钟";
+    }
+
+    public static bool IsText(string ext)
+        => ext is ".txt" or ".md" or ".xml" or ".json" or ".csv" or ".log" or ".ini" or ".conf"
+            or ".srt" or ".html" or ".htm" or ".css" or ".js" or ".ts" or ".cs" or ".java" or ".sql"
+            or ".yml" or ".yaml" or ".sh" or ".bat" or ".ps1" or ".py" or ".go" or ".c" or ".h" or ".php";
+
+    public static bool IsPdfOrImage(string mime)
+        => mime is "application/pdf"
+            or "image/png" or "image/jpeg" or "image/gif" or "image/webp" or "image/bmp" or "image/svg+xml";
+
+    public static bool IsVideoWhitelist(string ext) => ext is ".mp4" or ".webm";
+    public static bool IsAudioWhitelist(string ext) => ext is ".mp3" or ".wav" or ".m4a" or ".aac" or ".ogg";
+}