Implemented FtpSource based on FluentFtp library

src/NAppUpdate.Framework/NAppUpdate.Framework.csproj

@@ -68,7 +68,11 @@
     <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
   </PropertyGroup>
   <ItemGroup>
+    <Reference Include="FluentFTP, Version=19.2.2.0, Culture=neutral, PublicKeyToken=f4af092b1d8df44f, processorArchitecture=MSIL">
+      <HintPath>..\..\..\packages\FluentFTP.19.2.2\lib\net35\FluentFTP.dll</HintPath>
+    </Reference>
     <Reference Include="System" />
+    <Reference Include="System.Web" />
     <Reference Include="System.Xml" />
   </ItemGroup>
   <ItemGroup>
@@ -97,6 +101,7 @@
       <DesignTime>True</DesignTime>
       <DependentUpon>Resources.resx</DependentUpon>
     </Compile>
+    <Compile Include="Sources\FtpSource.cs" />
     <Compile Include="Sources\IUpdateSource.cs" />
     <Compile Include="Sources\MemorySource.cs" />
     <Compile Include="Sources\SimpleWebSource.cs" />
@@ -123,6 +128,7 @@
       <SubType>Designer</SubType>
     </EmbeddedResource>
     <None Include="NAppUpdate.snk" />
+    <None Include="packages.config" />
     <None Include="Updater\updater.exe" />
   </ItemGroup>
   <ItemGroup>

src/NAppUpdate.Framework/Sources/FtpSource.cs

@@ -0,0 +1,83 @@
+using System;
+using System.IO;
+using System.Net;
+using System.Text;
+using System.Web.UI.WebControls;
+using FluentFTP;
+using NAppUpdate.Framework.Common;
+
+namespace NAppUpdate.Framework.Sources
+{
+	public class FtpSource : IUpdateSource
+	{
+		public string HostUrl { get; set; }
+
+		private string feedPath { get; }
+
+		private string feedBasePath => Path.GetDirectoryName(feedPath);
+
+		private FtpClient ftpClient { get; }
+
+		/// <param name="hostUrl">Url of ftp server ("ftp://somesite.com/")</param>
+		/// <param name="feedPath">Local ftp path to feed ("/path/to/feed.xml")</param>
+		/// <param name="login">Login of ftp user, if needed</param>
+		/// <param name="password">Password of ftp user, if needed</param>
+		public FtpSource(string hostUrl, string feedPath, string login = null, string password = null)
+		{
+			ftpClient = new FtpClient(hostUrl);
+			HostUrl = hostUrl;
+			this.feedPath = feedPath;
+
+			if (login != null && password != null)
+			{
+				ftpClient.Credentials = new NetworkCredential(login, password);
+			}
+		}
+
+		private void TryConnectToHost()
+		{
+			try
+			{
+				ftpClient.Connect();
+			}
+			catch(Exception e)
+			{
+				throw new WebException($"Failed to connect to host: {HostUrl}. Error message: {e.Message}");
+			}
+		}
+
+		#region IUpdateSource Members
+
+		public String GetUpdatesFeed()
+		{
+			TryConnectToHost();
+
+			string data = null;
+
+			using (var fileStream = ftpClient.OpenRead(feedPath, FtpDataType.ASCII, true))
+			{
+				using (var streamReader = new StreamReader(fileStream))
+				{
+					data = streamReader.ReadToEnd();
+				}
+			}
+
+			// Remove byteorder mark if necessary
+			int indexTagOpening = data.IndexOf('<');
+			if (indexTagOpening > 0)
+			{
+				data = data.Substring(indexTagOpening);
+			}
+
+			return data;
+		}
+
+		public Boolean GetData(String filePath, String basePath, Action<UpdateProgressInfo> onProgress, ref String tempLocation)
+		{
+			ftpClient.DownloadFile(tempLocation, Path.Combine(feedBasePath, filePath));
+			return true;
+		}
+
+		#endregion
+	}
+}

src/NAppUpdate.Framework/packages.config

@@ -0,0 +1,4 @@
+<?xml version="1.0" encoding="utf-8"?>
+<packages>
+  <package id="FluentFTP" version="19.2.2" targetFramework="net35" />
+</packages>