Check HOSTS file - C# WinForms

Hello,

In today's post i'm giving a good (and simple) anti-hacking tool which allow your application to CHECK for any changes in the Windows HOSTS file.

So, the operation is simple:
Just read the hosts file content, and validate that your site DNS is not included in the list.
[basiclly, check if hosts file contains your dns name]
if so, the user probably is trying to bypass your server so you can stop him from doing so.

The code:

static bool IsDnsByPassed(string p_dnsName)
{
    string path = Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.System), @"drivers\etc\hosts");
    string hostsText = File.ReadAllText(path);
    return hostsText.ToLower().Contains(p_dnsName.ToLower());
}

Note:
Although reading the HOSTS file is allowed to all user, do not try to edit the HOSTS file, because on Vista & Windows7 this operation is allowed only for administrators. if your application is NOT running as Admin, then you won't have permission for this (and an Exception will be thrown).

Best regard,
MDB-Blog

C# | Determine if Adobe (Macromedia) Flash player installed.

All started when I needed to integrate an Adobe (Macromedia) Flash object in my C# WinForm application.
I saw several posts about it, where two solutions where presents:
1. Add WebBrowser Control and just nevigate to the "test.swf" file.
2. Create COM object of ADOBE MACROMEDIA.

I liked the 1st option more, because I don't need to handle COM objects (and to add another DLL to the app).
Here is the code I used:

WebBrowser wb = new WebBrowser();
//wb.Location = SOME LOCATION
//wb.Size = SOME SIZE
wb.AllowNavigation = false;
wb.IsWebBrowserContextMenuEnabled = false;
this.Controls.Add(wb); // this = FORM
wb.Navigate(@"C:\test.swf");

BUT, Then i noticed that when a pc do NOT have Adobe (Macromedia) Flash player installed, the webbrowser display a big red X.
SO, before I use the FLASH image in my winform application, I needed to check if FLASH player is INSTALLED or not!

The idea is to check the registry for:

HKEY_LOCAL_MACHINE\SOFTWARE\Macromedia\FlashPlayer\CurrentVersion

And indeed it worked!
Here is the full code for testing if FLASH installed (and also get the major Version):

internal static int? GetFlashPlayerVersion()
{
    using (RegistryKey rk = Registry.LocalMachine.OpenSubKey(@"SOFTWARE\Macromedia\FlashPlayer"))
    {
        if (rk != null)
        {
            string version = rk.GetValue("CurrentVersion") as string;
            if (string.IsNullOrEmpty(version) == false)
            {
                int idx = version.IndexOf(",");
                if (idx > 0)
                {
                    int value;
                    if (int.TryParse(version.Substring(0, idx), out value) == true)
                    {
                        return value;
                    }
                }
            }
        }
    }
    return null;
}

And the code which using the method:

int? flashVersion = WindowsUtils.GetFlashPlayerVersion();
if (flashVersion.HasValue == true && flashVersion > 6)
{
    WebBrowser wb = new WebBrowser();
    wb.AllowNavigation = false;
    wb.IsWebBrowserContextMenuEnabled = false;
    this.Controls.Add(wb); // this = FORM
    wb.Navigate(@"C:\test.swf");
}

Best regards,
MDB-Blog

C# | Check if app is installed for “All users” or "Just me"

Today I bring a very HARD-to-find topic about getting an installed application "Installation context".
An installation context may be Per-Machine Installation Context (ALLUSERS=1) and Per-User Installation Context (ALLUSERS="").

When installing an application, the user may select one of two options:
a. Install [APP] for yourself
b. or for anyone who uses this computer
[a] installs only for the current user(just me) while [b] installs for the Local System user which is for all-users(everyone).

In this post I will give a code for checking is an installed application was installed for "Everyone" or "Just me".

The validation process is check if the APPLICATION-NAME exists in the registry keys under UserData.
(*) Everyone - check under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Products\ (S-1-5-18 represents the Local System user)

(*) Just me (Current user) - check under HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-?!?!?!?!\Products\ (S-?!?!?!?! represents the Current user. this value found by the code: WindowsIdentity.GetCurrent().User.Value.


[Code] Method's return type:

private enum InstallationContexts { NotInstalled, Everyone, JustMe };

[Code] Method declaration:

private InstallationContexts GetInstalledContext(string p_appDisplayName)
{
    //The S-1-5-18  =
Local System user (Everyone) | HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-1-5-18\Products\

    //The S-XXXXXX  =
Current user (Just me)       |
HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\S-?!?!?!?!\Products\

    string key;
    string keyFormat = @"SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\{0}\Products\";
 
    // Check if installed for -> Everyone
    key = string.Format(keyFormat, "S-1-5-18");
    bool res = GetInstalledContext_IsRegKeyExists(key, p_appDisplayName, StringComparison.OrdinalIgnoreCase);
    if (res == true)
    {
        return InstallationContexts.Everyone;
    }
 
    // Check if installed for -> Just me
    key = string.Format(keyFormat, WindowsIdentity.GetCurrent().User.Value);
    res = GetInstalledContext_IsRegKeyExists(key, p_appDisplayName, StringComparison.OrdinalIgnoreCase);
    if (res == true)
    {
        return InstallationContexts.JustMe;
    }
 
    return InstallationContexts.NotInstalled;
}
private bool GetInstalledContext_IsRegKeyExists(string p_regKey, string p_appDisplayName, StringComparison p_scompare)
{
    using (RegistryKey regkey = Registry.LocalMachine.OpenSubKey(p_regKey))
    {
        if (regkey != null)
        {
            RegistryKey rk;
            string[] arrProducs = regkey.GetSubKeyNames();
            for (int i = 0; i < arrProducs.Length; i++)
            {
               using (rk = regkey.OpenSubKey(arrProducs[i] + @"\InstallProperties"))
               {
if (rk != null &&
                        p_appDisplayName.Equals(rk.GetValue("DisplayName").ToString(), p_scompare) == true)
                   {
                        return true;
                   }
               }
            }
        }
    }
 
    return false;
}

[Code] Method's usage example:

InstallationContexts appContext = GetInstalledContext("APP-DISPLAY-NAME");

This code gives the ability to detect previously installed application or previously installed software is installed to ALLUSERS (everyone) or only to CURRENT USER (just me).



Addition on 19.12.2010:
(*) This checking operation is valid ONLY for an application and software which were installed using Microsoft's Windows Installer.
For general checking for installed application, check my post about check if program/application is installed.


Enjoy...
MDB-Blog

C# | Winforms | Textbox within Button

Here is an example for creating a Button control which contains a Textbox inside it.
This is very usefull when the button functionality is based (only) on the textbox content text, and it is very usefull for the user.

Screenshot (image) example:

The Code:

class ButtonWithTextbox : Button
{
    TextBox _textbox = new TextBox();

    public int TextboxWidth
    {
        get { return _textbox.Width; }
        set { _textbox.Width = value; }
    }
    public Point TextboxLocation
    {
        get { return _textbox.Location; }
        set { _textbox.Location = value; }
    }
    /** And we may add all properties of the Textbox ***/

    public ButtonWithTextbox()
    {
        this.Controls.Add(_textbox);
    }
}

Also work great on the designer... :)

MDB-Blog
http://mdb-blog.blogspot.com

Trim Image white-spaces (black&white) | C# Winforms

I searched for a simple code that preform "TRIMMING" to an image.
By "trimming" i mean, that if i have a LARGE image that contains information (painting/drawing...) only in small part of the image and all other is white-space (WHITE or BLACK pixels).

I needed to remove such whitespace and also to decrease image size.
Following three code examples:

Code #1 - Gets the NON-WHITE-SPACE bounds of an image

private Rectangle GetImageNonWhiteSpaceBounds(Bitmap p_img, bool p_isBlackWhitespace)
{
    Rectangle rect = new Rectangle();
    unsafe
    {
        BitmapData bdActual = null;
        try
        {
            int width = p_img.Width;
            int height = p_img.Height;

            bdActual = p_img.LockBits(new Rectangle(0, 0, width, height), System.Drawing.Imaging.ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
            Int32 i;
            Int32 pSize = 3;
            Byte whiteTrashold = (Byte)240;
            Byte blackTrashold = (Byte)10;
            Byte* sourceRow;

            Int32 minX = width;
            Int32 maxX = 0;
            Int32 minY = height;
            Int32 maxY = 0;
            bool isWhitepace;

            for (Int32 _y = 0; _y < height; ++_y)             {                 sourceRow = (Byte*)bdActual.Scan0 + (_y * bdActual.Stride);                 for (Int32 _x = 0; _x < width; ++_x)                 {                     i = _x * pSize;                     isWhitepace =                         (p_isBlackWhitespace && sourceRow[i] <= blackTrashold && sourceRow[i + 1] <= blackTrashold && sourceRow[i + 2] <= blackTrashold)                         ||                         (!p_isBlackWhitespace && sourceRow[i] >= whiteTrashold && sourceRow[i + 1] >= whiteTrashold && sourceRow[i + 2] >= whiteTrashold);

                    if (isWhitepace == false)
                    {
                        // NO whitespace!!!
                        minX = Math.Min(_x, minX);
                        maxX = Math.Max(_x, maxX);

                        minY = Math.Min(_y, minY);
                        maxY = Math.Max(_y, maxY);
                    }
                }
            }

            rect.X = minX;
            rect.Y = minY;
            rect.Width = maxX - minX;
            rect.Height = maxY - minY;
        }
        finally
        {
            if (bdActual != null)
            {
                p_img.UnlockBits(bdActual);
            }
        }
    }
    return rect;
}

Code #2 - Draw rectangle around the NON-WHITE-SPACE

private void DrawNonWhiteSpaceRectangle(Bitmap p_img, bool p_isBlackWhitespace, Color p_color)
{
    unsafe
    {
        BitmapData bdActual = null;
        try
        {
            int width = p_img.Width;
            int height = p_img.Height;

            bdActual = p_img.LockBits(new Rectangle(0, 0, width, height), System.Drawing.Imaging.ImageLockMode.ReadWrite, PixelFormat.Format24bppRgb);
            Int32 i;
            Int32 pSize = 3;
            Byte whiteTrashold = (Byte)240;
            Byte blackTrashold = (Byte)10;
            Byte* sourceRow;

            Int32 minX = width;
            Int32 maxX = 0;
            Int32 minY = height;
            Int32 maxY = 0;
            bool isWhitepace;

            for (Int32 _y = 0; _y < height; ++_y)             {                 sourceRow = (Byte*)bdActual.Scan0 + (_y * bdActual.Stride);                 for (Int32 _x = 0; _x < width; ++_x)                 {                     i = _x * pSize;                     isWhitepace =                         (p_isBlackWhitespace && sourceRow[i] <= blackTrashold && sourceRow[i + 1] <= blackTrashold && sourceRow[i + 2] <= blackTrashold)                         ||                         (!p_isBlackWhitespace && sourceRow[i] >= whiteTrashold && sourceRow[i + 1] >= whiteTrashold && sourceRow[i + 2] >= whiteTrashold);

                    if (isWhitepace == false)
                    {
                        // NO whitespace!!!
                        minX = Math.Min(_x, minX);
                        maxX = Math.Max(_x, maxX);

                        minY = Math.Min(_y, minY);
                        maxY = Math.Max(_y, maxY);
                    }
                }
            }

            // draw rectagle:
            for (Int32 _y = minY; _y <= maxY; ++_y)             {                 sourceRow = (Byte*)bdActual.Scan0 + (_y * bdActual.Stride);                 i = minX * pSize;                 sourceRow[i] = (Byte)p_color.R;                 sourceRow[i + 1] = (Byte)p_color.G;                 sourceRow[i + 2] = (Byte)p_color.B;                 i = maxX * pSize;                 sourceRow[i] = (Byte)p_color.R;                 sourceRow[i + 1] = (Byte)p_color.G;                 sourceRow[i + 2] = (Byte)p_color.B;             }             Byte* sourceRowX1 = (Byte*)bdActual.Scan0 + (minY * bdActual.Stride);             Byte* sourceRowX2 = (Byte*)bdActual.Scan0 + (maxY * bdActual.Stride);             for (Int32 _x = minX; _x <= maxX; ++_x)             {                 i = _x * pSize;                 sourceRowX1[i] = (Byte)p_color.R;                 sourceRowX1[i + 1] = (Byte)p_color.G;                 sourceRowX1[i + 2] = (Byte)p_color.B;                 sourceRowX2[i] = (Byte)p_color.R;                 sourceRowX2[i + 1] = (Byte)p_color.G;                 sourceRowX2[i + 2] = (Byte)p_color.B;             }         }         finally         {             if (bdActual != null)             {                 p_img.UnlockBits(bdActual);             }         }     } }

Code #3 - Trim Image whitespaces

private Bitmap CropImageWhitespaces(Bitmap p_img, bool p_isBlackWhitespace)
{
    Rectangle rect = new Rectangle();
    unsafe
    {
        BitmapData bdActual = null;
        try
        {
            int width = p_img.Width;
            int height = p_img.Height;

            bdActual = p_img.LockBits(new Rectangle(0, 0, width, height), System.Drawing.Imaging.ImageLockMode.ReadOnly, PixelFormat.Format24bppRgb);
            Int32 i;
            Int32 pSize = 3;
            Byte whiteTrashold = (Byte)240;
            Byte blackTrashold = (Byte)10;
            Byte* sourceRow;

            Int32 minX = width;
            Int32 maxX = 0;
            Int32 minY = height;
            Int32 maxY = 0;
            bool isWhitepace;

            for (Int32 _y = 0; _y < height; ++_y)             {                 sourceRow = (Byte*)bdActual.Scan0 + (_y * bdActual.Stride);                 for (Int32 _x = 0; _x < width; ++_x)                 {                     i = _x * pSize;                     isWhitepace =                         (p_isBlackWhitespace && sourceRow[i] <= blackTrashold && sourceRow[i + 1] <= blackTrashold && sourceRow[i + 2] <= blackTrashold)                         ||                         (!p_isBlackWhitespace && sourceRow[i] >= whiteTrashold && sourceRow[i + 1] >= whiteTrashold && sourceRow[i + 2] >= whiteTrashold);

                    if (isWhitepace == false)
                    {
                        // NO whitespace!!!
                        minX = Math.Min(_x, minX);
                        maxX = Math.Max(_x, maxX);

                        minY = Math.Min(_y, minY);
                        maxY = Math.Max(_y, maxY);
                    }
                }
            }

            rect.X = minX;
            rect.Y = minY;
            rect.Width = maxX - minX;
            rect.Height = maxY - minY;
        }
        finally
        {
            if (bdActual != null)
            {
                p_img.UnlockBits(bdActual);
            }
        }
    }

    return p_img.Clone(rect, p_img.PixelFormat);
}

I hope it will be helpful for you.
this code if fast and easy to use.