Upload file to Secured FTP in ASP.NET - asp.net

Question

I want to upload files to FTPS and SFTP. My code is currently using FtpWebRequest object to upload to FTP. What changes or class should I use to upload to FTP, FTPS and SFTP servers?

Answer 1

SFTP is not a built-in protocol for .NET, you'll have to use a third-party library, like SharpSSH; however, FTP and FTPS are. There are a number of third-party libraries both commercial and OpenSource (SSH Factory for .NET , Rebex SFTP for .NET/.NET CF, SharpSSH - A Secure Shell (SSH) library for .NET, Compare SFTP (SSH File Transfer Protocol) components for .NET (C#, VB.NET) - SecureBlackbox®) and you'll need to do some research to determine which one will best suit your needs.
Here's a sample console app I wrote that does FTP and FTPS using the .NET Framework's FtpWebRequest:
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Sockets;
using System.Net.Security;
using System.Security.Cryptography.X509Certificates;
using System.Text;
namespace FtpSslTest
{
class Program
{
static void Main(string[] args)
{
string server = null;
do
{
Console.Write("Enter the server to connect to: ");
server = Console.ReadLine();
} while (IsServerValid(server) == false);
UriBuilder ftpUrl = new UriBuilder("ftp", server);
bool useSsl = GetYesNo("Use SSL?");
bool allowInvalidCertificate = false;
if (useSsl)
{
allowInvalidCertificate = GetYesNo("Allow invalid SSL certificate?");
}
bool useActiveFtp = GetYesNo("Use Active FTP?");
string path = null;
do
{
Console.Write("Enter the path: ");
path = Console.ReadLine();
} while (IsValidPath(path) == false);
ftpUrl.Path = path;
Console.Write("Enter the user name: ");
string userName = Console.ReadLine();
string password = GetPasswordFromUser();
Console.WriteLine();
Console.WriteLine();
List<string> directoryContents = null;
try
{
directoryContents = DisplayDirectoryContents(ftpUrl.ToString(), userName, password, useSsl, allowInvalidCertificate, useActiveFtp, false);
}
catch (WebException ex)
{
Console.WriteLine("The request failed with status {0}. {1}", ex.Status, ex.Message);
}
catch (Exception ex)
{
Console.Error.WriteLine(ex.ToString());
}
if (directoryContents != null && directoryContents.Count == 1)
{
bool saveFile = GetYesNo(string.Format("Download the file {0} from {1}? ", directoryContents[0], server));
if (saveFile)
{
string savePath = null;
do
{
Console.Write("Enter a local path to save the file: ");
savePath = Console.ReadLine();
} while (!IsValidPath(savePath));
try
{
DownloadFileFromServer(ftpUrl.ToString(), userName, password, useSsl, allowInvalidCertificate, useActiveFtp, savePath);
}
catch (WebException ex)
{
Console.WriteLine("The request failed with status {0}. {1}", ex.Status, ex.Message);
}
catch (Exception ex)
{
Console.Error.WriteLine(ex.ToString());
}
}
}
}
private static bool GetYesNo(string message)
{
Console.Write("{0} (Y/N) ", message);
string input = null;
do
{
input = new string(Console.ReadKey(true).KeyChar, 1);
} while (!input.Equals("Y", StringComparison.CurrentCultureIgnoreCase) && !input.Equals("N", StringComparison.CurrentCultureIgnoreCase));
Console.WriteLine(input);
return input.Equals("Y", StringComparison.CurrentCultureIgnoreCase);
}
private static bool IsValidPath(string path)
{
bool validPath = false;
validPath = path != null && path.IndexOfAny(Path.GetInvalidPathChars()) < 0;
if (validPath == false)
{
Console.WriteLine("You must enter a valid path.");
}
return validPath;
}
private static bool IsServerValid(string server)
{
bool serverValid = false;
if (!string.IsNullOrEmpty(server))
{
try
{
IPAddress[] addresses = Dns.GetHostAddresses(server);
serverValid = (addresses != null && addresses.Length > 0);
}
catch (SocketException ex)
{
Console.WriteLine(ex.Message);
}
}
else
{
Console.WriteLine("You must provide a valid host name or IP address.");
}
return serverValid;
}
private static string GetPasswordFromUser()
{
Console.Write("Enter the password: ");
StringBuilder password = new StringBuilder();
char readChar = '\x00';
while (readChar != '\r')
{
readChar = Console.ReadKey(true).KeyChar;
if (readChar == '\b')
{
if (password.Length > 0)
{
password.Length--;
Console.Write("\b \b");
}
}
else if (readChar != '\r')
{
Console.Write('*');
password.Append(readChar);
}
}
return password.ToString();
}
public static bool ServicePointManager_ServerCertificateValidationCallback(object sender, X509Certificate certificate, X509Chain chain, SslPolicyErrors sslPolicyErrors)
{
bool allowCertificate = true;
if (sslPolicyErrors != SslPolicyErrors.None)
{
Console.WriteLine("Accepting the certificate with errors:");
if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateNameMismatch) == SslPolicyErrors.RemoteCertificateNameMismatch)
{
Console.WriteLine("\tThe certificate subject {0} does not match.", certificate.Subject);
}
if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateChainErrors) == SslPolicyErrors.RemoteCertificateChainErrors)
{
Console.WriteLine("\tThe certificate chain has the following errors:");
foreach (X509ChainStatus chainStatus in chain.ChainStatus)
{
Console.WriteLine("\t\t{0}", chainStatus.StatusInformation);
if (chainStatus.Status == X509ChainStatusFlags.Revoked)
{
allowCertificate = false;
}
}
}
if ((sslPolicyErrors & SslPolicyErrors.RemoteCertificateNotAvailable) == SslPolicyErrors.RemoteCertificateNotAvailable)
{
Console.WriteLine("No certificate available.");
allowCertificate = false;
}
Console.WriteLine();
}
return allowCertificate;
}
private static FtpWebRequest CreateFtpWebRequest(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp)
{
FtpWebRequest request = (FtpWebRequest)WebRequest.Create(ftpUrl);
request.Credentials = new NetworkCredential(userName, password);
if (useSsl)
{
request.EnableSsl = true;
if (allowInvalidCertificate)
{
ServicePointManager.ServerCertificateValidationCallback = ServicePointManager_ServerCertificateValidationCallback;
}
else
{
ServicePointManager.ServerCertificateValidationCallback = null;
}
}
request.UsePassive = !useActiveFtp;
return request;
}
private static List<string> DisplayDirectoryContents(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp, bool detailed)
{
List<string> directoryContents = new List<string>();
FtpWebRequest request = CreateFtpWebRequest(ftpUrl, userName, password, useSsl, allowInvalidCertificate, useActiveFtp);
if (detailed)
{
request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
}
else
{
request.Method = WebRequestMethods.Ftp.ListDirectory;
}
Stopwatch stopwatch = new Stopwatch();
long bytesReceived = 0;
stopwatch.Start();
using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
{
Console.WriteLine(response.BannerMessage);
Console.WriteLine(response.WelcomeMessage);
Console.WriteLine(response.StatusDescription);
using (Stream responseStream = response.GetResponseStream())
using (StreamReader responseStreamReader = new StreamReader(responseStream))
{
while (!responseStreamReader.EndOfStream)
{
string directoryEntry = responseStreamReader.ReadLine();
Console.WriteLine(directoryEntry);
directoryContents.Add(directoryEntry);
}
}
Console.WriteLine(response.ExitMessage);
}
stopwatch.Stop();
Console.WriteLine();
Console.WriteLine("{0} bytes received in {1} seconds.", bytesReceived, stopwatch.ElapsedMilliseconds / 1000.0);
return directoryContents;
}
private static List<string> ListDirectoryContents(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp, bool detailed)
{
List<string> directoryContents = new List<string>();
FtpWebRequest request = CreateFtpWebRequest(ftpUrl, userName, password, useSsl, allowInvalidCertificate, useActiveFtp);
if (detailed)
{
request.Method = WebRequestMethods.Ftp.ListDirectoryDetails;
}
else
{
request.Method = WebRequestMethods.Ftp.ListDirectory;
}
using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
{
using (Stream responseStream = response.GetResponseStream())
using (StreamReader responseStreamReader = new StreamReader(responseStream))
{
while (!responseStreamReader.EndOfStream)
{
string directoryEntry = responseStreamReader.ReadLine();
directoryContents.Add(directoryEntry);
}
}
}
return directoryContents;
}
private static void DownloadFileFromServer(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp, string savePath)
{
FtpWebRequest request = CreateFtpWebRequest(ftpUrl, userName, password, useSsl, allowInvalidCertificate, useActiveFtp);
request.Method = WebRequestMethods.Ftp.DownloadFile;
Stopwatch stopwatch = new Stopwatch();
long bytesReceived = 0;
stopwatch.Start();
using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
{
Console.WriteLine(response.BannerMessage);
Console.WriteLine(response.WelcomeMessage);
Console.WriteLine(response.StatusDescription);
using (Stream responseStream = response.GetResponseStream())
using (FileStream saveFileStream = File.OpenWrite(savePath))
{
// Note that this method call requires .NET 4.0 or higher. If using an earlier version it will need to be replaced.
responseStream.CopyTo(saveFileStream);
}
bytesReceived = response.ContentLength;
Console.WriteLine(response.ExitMessage);
}
stopwatch.Stop();
Console.WriteLine();
Console.WriteLine("{0} bytes received in {1} seconds.", bytesReceived, stopwatch.ElapsedMilliseconds / 1000.0);
}
private static void UploadFileToServer(string ftpUrl, string userName, string password, bool useSsl, bool allowInvalidCertificate, bool useActiveFtp, string filePath)
{
FtpWebRequest request = CreateFtpWebRequest(ftpUrl, userName, password, useSsl, allowInvalidCertificate, useActiveFtp);
request.Method = WebRequestMethods.Ftp.UploadFile;
Stopwatch stopwatch = new Stopwatch();
long bytesReceived = 0;
stopwatch.Start();
long bytesSent = 0;
using (Stream requestStream = request.GetRequestStream())
using (FileStream uploadFileStream = File.OpenRead(filePath))
{
// Note that this method call requires .NET 4.0 or higher. If using an earlier version it will need to be replaced.
uploadFileStream.CopyTo(requestStream);
bytesSent = uploadFileStream.Position;
}
using (FtpWebResponse response = (FtpWebResponse)request.GetResponse())
{
Console.WriteLine(response.BannerMessage);
Console.WriteLine(response.WelcomeMessage);
Console.WriteLine(response.StatusDescription);
bytesReceived = response.ContentLength;
Console.WriteLine(response.ExitMessage);
}
stopwatch.Stop();
Console.WriteLine();
Console.WriteLine("{0} bytes sent in {1} seconds.", bytesSent, stopwatch.ElapsedMilliseconds / 1000.0);
}
}
}
You can also get detailed tracing for debugging purposes by using the following config file with the sample application:
<?xml version="1.0"?>
<configuration>
<system.diagnostics>
<sources>
<source name="System.Net">
<listeners>
<add name="TraceFile"/>
</listeners>
</source>
<source name="System.Net.Sockets" maxdatasize="1024">
<listeners>
<add name="TraceFile"/>
</listeners>
</source>
</sources>
<sharedListeners>
<add name="TraceFile" type="System.Diagnostics.TextWriterTraceListener" initializeData="System.Net.trace.log" traceOutputOptions="DateTime"/>
</sharedListeners>
<switches>
<add name="System.Net" value="Verbose"/>
<!--<add name="System.Net.Sockets" value="Verbose"/>-->
</switches>
<trace autoflush="true" />
</system.diagnostics>
<startup>
<supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/>
</startup>
</configuration>

Answer 2

I use this library to download and upload files over sftp. Should be samples of how to use the library if you download the source. http://sshnet.codeplex.com