Added mailboxes as local data sources (#1022)

app/MindWork AI Studio/Tools/Mail/MailServerHosts.cs

@@ -0,0 +1,52 @@
+using System.Globalization;
+
+namespace AIStudio.Tools.Mail;
+
+public static class MailServerHosts
+{
+    /// <summary>
+    /// The host in the form certificates and the allowed hosts for root certificates use.
+    /// </summary>
+    /// <param name="host">The host as somebody wrote it, e.g., with umlauts or surrounding white space.</param>
+    /// <param name="idnHost">The host in its ASCII form, or an IP address as written.</param>
+    /// <returns>True when the text is a host name or an IP address.</returns>
+    public static bool TryGetIdnHost(string host, out string idnHost)
+    {
+        idnHost = host.Trim();
+        switch (Uri.CheckHostName(idnHost))
+        {
+            case UriHostNameType.IPv4:
+            case UriHostNameType.IPv6:
+                return true;
+
+            case UriHostNameType.Dns:
+                try
+                {
+                    idnHost = new IdnMapping().GetAscii(idnHost);
+                    return true;
+                }
+                catch (ArgumentException)
+                {
+                    return false;
+                }
+
+            default:
+                return false;
+        }
+    }
+
+    /// <summary>
+    /// Whether two hosts name the same server, however each was written.
+    /// </summary>
+    /// <remarks>
+    /// Case, umlauts against their ASCII form, and a closing dot make no difference. A text which
+    /// is no host at all is the same as nothing.
+    /// </remarks>
+    /// <param name="host">The one host.</param>
+    /// <param name="otherHost">The other host.</param>
+    /// <returns>True when both are hosts and name the same server.</returns>
+    public static bool AreSame(string host, string otherHost) =>
+        TryGetIdnHost(host, out var idnHost) &&
+        TryGetIdnHost(otherHost, out var otherIdnHost) &&
+        idnHost.TrimEnd('.').Equals(otherIdnHost.TrimEnd('.'), StringComparison.OrdinalIgnoreCase);
+}