multipart/form-data support

Network/Platforms/iOS/Structs/NSMultipartFormData.cs

@@ -0,0 +1,66 @@
+using Foundation;
+
+namespace Blahblah.Library.Network;
+
+class NSMultipartFormData
+{
+    public const string DefaultMimeType = "application/octet-stream";
+
+    public NSMutableData Data => boundaryData;
+
+    readonly string boundary;
+    readonly NSMutableData boundaryData;
+
+    public string ContentType => $"{NetworkHelper.ContentFormData}; boundary={boundary}";
+
+    public NSMultipartFormData()
+    {
+        var data = new byte[12];
+        for (var i = 0; i < 12; i++)
+        {
+            data[i] = (byte)(Random.Shared.Next(0x30, 0x3a));
+        }
+        var id = Convert.ToBase64String(data);
+        boundary = $"----WebKitFormBoundary{id}";
+        boundaryData = new NSMutableData();
+    }
+
+    public void AddTextField(string name, string value)
+    {
+        // Content-Type: text/plain; charset=ISO-8859-1
+        // Content-Transfer-Encoding: 8bit
+
+        var field = $"--{boundary}\r\n" +
+            $"Content-Disposition: form-data; name=\"{name}\"\r\n\r\n" +
+            $"{value}\r\n";
+        boundaryData.AppendData(NSData.FromString(field, NSStringEncoding.UTF8));
+    }
+
+    public void AddDataField(string name, Stream data, string? fileName = null, string mimeType = DefaultMimeType)
+    {
+        if (fileName == null)
+        {
+            fileName = "";
+        }
+        else if (!string.IsNullOrEmpty(fileName))
+        {
+            fileName = $"; filename=\"{fileName}\"";
+        }
+        var field = $"--{boundary}\r\n" +
+            $"Content-Disposition: form-data; name=\"{name}\"{fileName}\r\n" +
+            $"Content-Type: {mimeType}\r\n\r\n";
+        boundaryData.AppendData(NSData.FromString(field, NSStringEncoding.UTF8));
+
+        var stream = NSData.FromStream(data);
+        if (stream != null)
+        {
+            boundaryData.AppendData(stream);
+        }
+        boundaryData.AppendData(NSData.FromString("\r\n"));
+    }
+
+    public void AddEnd()
+    {
+        boundaryData.AppendData(NSData.FromString($"--{boundary}--"));
+    }
+}