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// Copyright (C) 2016, The Duplicati Team
// http://www.duplicati.com, info@duplicati.com
//
// This library is free software; you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as
// published by the Free Software Foundation; either version 2.1 of the
// License, or (at your option) any later version.
//
// This library is distributed in the hope that it will be useful, but
// WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
// Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public
// License along with this library; if not, write to the Free Software
// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
using System;
using System.Linq;
using System.Collections.Generic;
namespace Duplicati.Server.WebServer.RESTMethods
{
public class Captcha : IRESTMethodGET, IRESTMethodPOST
{
private class CaptchaEntry
{
public readonly string Answer;
public readonly string Target;
public int Attempts;
public readonly DateTime Expires;
public CaptchaEntry(string answer, string target)
{
Answer = answer;
Target = target;
Attempts = 4;
Expires = DateTime.Now.AddMinutes(2);
}
}
private static object m_lock = new object();
private static Dictionary<string, CaptchaEntry> m_captchas = new Dictionary<string, CaptchaEntry>();
public static bool SolvedCaptcha(string token, string target, string answer)
{
lock(m_lock)
{
CaptchaEntry tp;
m_captchas.TryGetValue(token ?? string.Empty, out tp);
if (tp == null)
return false;
if (tp.Attempts > 0)
tp.Attempts--;
return tp.Attempts >= 0 && string.Equals(tp.Answer, answer, StringComparison.OrdinalIgnoreCase) && tp.Target == target && tp.Expires >= DateTime.Now;
}
}
public void GET(string key, RequestInfo info)
{
if (string.IsNullOrWhiteSpace(key))
{
info.ReportClientError("Missing token value", System.Net.HttpStatusCode.Unauthorized);
return;
}
else
{
string answer = null;
lock (m_lock)
{
CaptchaEntry tp;
m_captchas.TryGetValue(key, out tp);
if (tp != null && tp.Expires > DateTime.Now)
answer = tp.Answer;
}
if (string.IsNullOrWhiteSpace(answer))
{
info.ReportClientError("No such entry", System.Net.HttpStatusCode.NotFound);
return;
}
using (var bmp = CaptchaUtil.CreateCaptcha(answer))
using (var ms = new System.IO.MemoryStream())
{
info.Response.ContentType = "image/jpeg";
info.Response.ContentLength = ms.Length;
bmp.Save(ms, System.Drawing.Imaging.ImageFormat.Jpeg);
ms.Position = 0;
info.Response.ContentType = "image/jpeg";
info.Response.ContentLength = ms.Length;
info.Response.SendHeaders();
ms.CopyTo(info.Response.Body);
info.Response.Send();
}
}
}
public void POST(string key, RequestInfo info)
{
if (string.IsNullOrWhiteSpace(key))
{
var target = info.Request.Param["target"].Value;
if (string.IsNullOrWhiteSpace(target))
{
info.ReportClientError("Missing target parameter", System.Net.HttpStatusCode.BadRequest);
return;
}
var answer = CaptchaUtil.CreateRandomAnswer(minlength: 6, maxlength: 6);
var nonce = Guid.NewGuid().ToString();
string token;
using (var ms = new System.IO.MemoryStream())
{
var bytes = System.Text.Encoding.UTF8.GetBytes(answer + nonce);
ms.Write(bytes, 0, bytes.Length);
ms.Position = 0;
token = Library.Utility.Utility.Base64PlainToBase64Url(Library.Utility.Utility.CalculateHash(ms));
}
lock (m_lock)
{
var expired = m_captchas.Where(x => x.Value.Expires < DateTime.Now).Select(x => x.Key).ToArray();
foreach (var x in expired)
m_captchas.Remove(x);
if (m_captchas.Count > 3)
{
info.ReportClientError("Too many captchas, wait 2 minutes and try again", System.Net.HttpStatusCode.ServiceUnavailable);
return;
}
m_captchas[token] = new CaptchaEntry(answer, target);
}
info.OutputOK(new
{
token = token
});
}
else
{
var answer = info.Request.Param["answer"].Value;
var target = info.Request.Param["target"].Value;
if (string.IsNullOrWhiteSpace(answer))
{
info.ReportClientError("Missing answer parameter", System.Net.HttpStatusCode.BadRequest);
return;
}
if (string.IsNullOrWhiteSpace(target))
{
info.ReportClientError("Missing target parameter", System.Net.HttpStatusCode.BadRequest);
return;
}
if (SolvedCaptcha(key, target, answer))
info.OutputOK();
else
info.ReportClientError("Incorrect", System.Net.HttpStatusCode.Forbidden);
}
}
}
}
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