From 5e7385a96bebc62fe2c94e526b3a939b6ead7259 Mon Sep 17 00:00:00 2001
From: "Frank A. Krueger" <fak@praeclarum.org>
Date: Tue, 22 Aug 2017 21:24:52 -0700
Subject: [PATCH] More work on decoding multipart form data

---
 Samples/FilesSample.cs | 94 +++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 93 insertions(+), 1 deletion(-)

diff --git a/Samples/FilesSample.cs b/Samples/FilesSample.cs
index 626cbb0..4adecbb 100644
--- a/Samples/FilesSample.cs
+++ b/Samples/FilesSample.cs
@@ -1,4 +1,5 @@
 using System;
+using System.Collections.Generic;
 using System.Net;
 using System.Threading;
 using Ooui;
@@ -35,11 +36,102 @@ namespace Samples
 			var ct = req.ContentType;
 			var bi = ct.IndexOf ("boundary=", StringComparison.InvariantCulture);
 			var boundaryString = ct.Substring (bi + 9);
-			var boundaryBytes = System.Text.Encoding.UTF8.GetBytes (boundaryString);
+			var boundaryBytes = System.Text.Encoding.UTF8.GetBytes ("--" + boundaryString + "\r\n");
 			var boundaryEndBytes = System.Text.Encoding.UTF8.GetBytes (boundaryString + "--");
+			var headerEndBytes = System.Text.Encoding.UTF8.GetBytes ("\r\n\r\n");
 			Console.WriteLine ("OMGGGGGG " + boundaryString);
+
+			var state = 0;
+			var buffer = new byte[1024];
+			var bufferLen = 0;
+
+			var needsRead = true;
+
+			using (var s = req.InputStream) {
+				while (state < 1000) {
+					if (needsRead) {
+						var r = buffer.Length - bufferLen;
+						if (r <= 0) {
+							Array.Resize (ref buffer, buffer.Length * 2);
+							r = buffer.Length - bufferLen;
+						}
+						var n = s.Read (buffer, bufferLen, r);
+						if (n > 0) {
+							bufferLen += n;
+						}
+						else if (n == 0) {
+							// End!
+							state = 1000;
+						}
+						else {
+							state = 1001;
+						}
+					}
+					switch (state) {
+						case 0:
+							var i = FindIndex (buffer, 0, bufferLen, boundaryBytes);
+							if (i >= 0) {
+								var e = i + boundaryBytes.Length;
+								var r = bufferLen - e;
+								Buffer.BlockCopy (buffer, e, buffer, 0, r);
+								bufferLen = r;
+								state = 1;
+							}
+							else {
+								needsRead = true;
+							}
+							break;
+						case 1:
+							i = FindIndex (buffer, 0, bufferLen, headerEndBytes);
+							if (i >= 0) {
+								var h = System.Text.Encoding.ASCII.GetString (buffer, 0, i);
+								Console.WriteLine ("HEADERS {0}", h);
+								var e = i + headerEndBytes.Length;
+								var r = bufferLen - e;
+								Buffer.BlockCopy (buffer, e, buffer, 0, r);
+								bufferLen = r;
+								state = 2;
+							}
+							else {
+								needsRead = true;
+							}
+							break;
+						case 2:
+							i = FindIndex (buffer, 0, bufferLen, boundaryEndBytes);
+							if (i >= 0) {
+								Console.WriteLine ("DATA {0}", bufferLen);
+								var data = new byte[bufferLen];
+								var e = i + boundaryBytes.Length;
+								var r = bufferLen - e;
+								Buffer.BlockCopy (buffer, e, buffer, 0, r);
+								bufferLen = r;
+								state = 0;
+							}
+							else {
+								needsRead = true;
+							}
+							break;
+					}
+				}
+			}
+
+			Console.WriteLine ("STATE " + state);
 			listenerContext.Response.StatusCode = 200;
 			listenerContext.Response.Close ();
 		}
+
+		static int FindIndex (byte[] buffer, int bufferStart, int bufferLen, byte[] pattern)
+		{
+			var n = pattern.Length;
+			for (var i = bufferLen - n; i >= bufferStart; i--) {
+				var all = true;
+				for (var j = 0; all && j < n; j++) {
+					all = buffer[i + j] == pattern[j];
+				}
+				if (all)
+					return i;
+			}
+			return -1;
+		}
 	}
 }