Initial commit: WpywMail 自建邮件系统：.NET 8 原生 SMTP/IMAP 服务端（DKIM 签名、SPF/DKIM/DMARC 入站校验、SQLite 存储、完整账号体系）、Node 服务端、WinUI 3 客户端与 Web 前端

server-native/Mime.cs

@@ -0,0 +1,47 @@
+using System.Text;
+
+namespace WpywMail.Native;
+
+public sealed record ParsedMime(string From, string To, string Subject, string MessageId, string Text);
+
+public static class Mime
+{
+    public static ParsedMime Parse(byte[] raw)
+    {
+        var value = Encoding.UTF8.GetString(raw).Replace("\r\n", "\n");
+        var split = value.IndexOf("\n\n", StringComparison.Ordinal);
+        var headerText = split >= 0 ? value[..split] : value;
+        var body = split >= 0 ? value[(split + 2)..] : "";
+        var headers = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
+        string? current = null;
+        foreach (var line in headerText.Split('\n'))
+        {
+            if ((line.StartsWith(' ') || line.StartsWith('\t')) && current is not null) headers[current] += " " + line.Trim();
+            else { var colon = line.IndexOf(':'); if (colon > 0) { current = line[..colon]; headers[current] = line[(colon + 1)..].Trim(); } }
+        }
+        return new ParsedMime(headers.GetValueOrDefault("From", ""), headers.GetValueOrDefault("To", ""), headers.GetValueOrDefault("Subject", "(无主题)"), headers.GetValueOrDefault("Message-ID", ""), body.TrimEnd());
+    }
+
+    public static byte[] Build(string from, string[] to, string subject, string text)
+    {
+        var body = WrapBase64(Encoding.UTF8.GetBytes(text));
+        var value = $"From: {from}\r\nTo: {string.Join(", ", to)}\r\nSubject: {EncodeHeader(subject)}\r\nDate: {DateTimeOffset.UtcNow:R}\r\nMessage-ID: <{Guid.NewGuid():N}@wpyw.site>\r\nMIME-Version: 1.0\r\nContent-Type: text/plain; charset=UTF-8\r\nContent-Transfer-Encoding: base64\r\n\r\n{body}\r\n";
+        return Encoding.UTF8.GetBytes(value);
+    }
+
+    private static string EncodeHeader(string value)
+    {
+        if (value.All(ch => ch <= 0x7F)) return value;
+        var encoded = Convert.ToBase64String(Encoding.UTF8.GetBytes(value));
+        return $"=?UTF-8?B?{encoded}?=";
+    }
+
+    private static string WrapBase64(byte[] bytes)
+    {
+        var encoded = Convert.ToBase64String(bytes);
+        return string.Join("\r\n", Enumerable.Range(0, (encoded.Length + 75) / 76)
+            .Select(index => encoded.Substring(index * 76, Math.Min(76, encoded.Length - index * 76))));
+    }
+
+    public static string[] Addresses(string value) => value.Split([',', ';'], StringSplitOptions.RemoveEmptyEntries | StringSplitOptions.TrimEntries).Select(x => x.Contains('<') ? x[(x.IndexOf('<') + 1)..x.IndexOf('>')] : x).Where(x => x.Contains('@')).ToArray();
+}