From 96e1f17aa9e5f7397726fd478f08c229cc727d3c Mon Sep 17 00:00:00 2001
From: Alexey 'Cluster' Avdyukhin <clusterrr@clusterrr.com>
Date: Tue, 11 Apr 2017 07:32:55 +0300
Subject: FTP server (seriously!) and many fixes

---
 FtpServer/FileSystemHelper.cs | 66 +++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 FtpServer/FileSystemHelper.cs

(limited to 'FtpServer/FileSystemHelper.cs')

diff --git a/FtpServer/FileSystemHelper.cs b/FtpServer/FileSystemHelper.cs
new file mode 100644
index 00000000..36cc4979
--- /dev/null
+++ b/FtpServer/FileSystemHelper.cs
@@ -0,0 +1,66 @@
+using System;
+using System.Collections.Generic;
+
+namespace mooftpserv
+{
+    public class FileSystemHelper
+    {
+        /// Handles TVFS path resolution, similar to Path.GetFullPath(Path.Combine(basePath, path))
+        public static string ResolvePath(string basePath, string path)
+        {
+            // CF is missing String.IsNullOrWhiteSpace
+            if (path == null || path.Trim() == "")
+                return null;
+
+            // first, make a complete unix path
+            string fullPath;
+            if (path[0] == '/') {
+                fullPath = path;
+            } else {
+                fullPath = basePath;
+                if (!fullPath.EndsWith("/"))
+                    fullPath += "/";
+                fullPath += path;
+            }
+
+            // then, remove ".." and "."
+            List<string> tokens = new List<string>(fullPath.Split('/'));
+            for (int i = 0; i < tokens.Count; ++i) {
+                if (tokens[i] == "") {
+                    if (i == 0 || i == tokens.Count - 1) {
+                        continue; // ignore, start and end should be empty tokens
+                    } else {
+                        tokens.RemoveAt(i);
+                        --i;
+                    }
+                } else if (tokens[i] == "..") {
+                    if (i < 2) {
+                        // cannot go higher than root, just remove the token
+                        tokens.RemoveAt(i);
+                        --i;
+                    } else {
+                        tokens.RemoveRange(i - 1, 2);
+                        i -= 2;
+                    }
+                } else if (i < tokens.Count - 1 && tokens[i].EndsWith(@"\")) {
+                    int slashes = 0;
+                    for (int c = tokens[i].Length - 1; c >= 0 && tokens[i][c] == '\\'; --c)
+                        ++slashes;
+
+                    if (slashes % 2 != 0) {
+                        // the slash was actually escaped, merge tokens
+                        tokens[i] += ("/" + tokens[i + 1]);
+                        ++i;
+                    }
+                }
+            }
+
+            if (tokens.Count > 1)
+                return String.Join("/", tokens.ToArray());
+            else
+                return "/";
+        }
+
+    }
+}
+
-- 
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