Converting a sequence to a dictionary using the ToDictionary LINQ operator

February 2, 2016 Leave a comment

Say you have a sequence of objects that you’d like to convert into a Dictionary for efficient access by key. Ideally the objects have some kind of “natural” key for the dictionary such as an ID:

public class Singer
{
	public int Id { get; set; }
	public string FirstName { get; set; }
	public string LastName { get; set; }
}

IEnumerable<Singer> singers = new List<Singer>() 
		{
			new Singer(){Id = 1, FirstName = "Freddie", LastName = "Mercury"} 
			, new Singer(){Id = 2, FirstName = "Elvis", LastName = "Presley"}
			, new Singer(){Id = 3, FirstName = "Chuck", LastName = "Berry"}
			, new Singer(){Id = 4, FirstName = "Ray", LastName = "Charles"}
			, new Singer(){Id = 5, FirstName = "David", LastName = "Bowie"}
		};

Read more of this post

Filed under .NET, LINQ Tagged with ,

Using client certificates in .NET part 7: working with client certificates in OWIN/Katana

February 1, 2016 Leave a comment

Introduction

In the previous post we accomplished a couple of things. First we secured our demo Web API website with a client certificate. Second we enabled client certificates for it so that IIS doesn’t just ignore them. Finally we saw that the client certificate is also picked up in the customers controller when sent in code in a web request.

In this post we’ll start discussing how to add client certificate handling as an OWIN middleware component.

Make sure you open the demo Web API project in Visual Studio as an administrator.

Read more of this post

Filed under .NET, Security Tagged with , , , , ,

Subscribing to cancel key press events in a .NET console application

January 29, 2016 Leave a comment

Users can stop and close a console application by any of the following methods:

  • Pressing the ‘x’ button in the top right hand corner
  • Pressing ctrl+c
  • Pressing ctrl+break

Occasionally you might want to check whether the user has pressed either ctrl+c or ctrl+break. The following code sample will show you how to do that.

Read more of this post

Filed under .NET, C# language features Tagged with ,

Using client certificates in .NET part 6: setting up client certificates for local test usage

January 28, 2016 10 Comments

Introduction

In the previous post we investigated how to attach a client certificate to the web request and how to extract it in a controller. We faced an issue that by default client certificates are ignored by IIS so we couldn’t actually read the certificate.

We’ll solve that problem in this post.

Read more of this post

Filed under .NET, Security Tagged with , , , , ,

How to find various machine-level system information with C# .NET

January 27, 2016 1 Comment

The Environment class holds a range of properties that help you describe the system your app is running on. Here come some examples with inline comments:

//returns true on my PC as it is a 64-bit OS
bool is64BitOperatingSystem = Environment.Is64BitOperatingSystem;
//returns the machine name, in my case ANDRAS1
string machineName = Environment.MachineName;
			
//returns information about the operating system version, build, major, minor etc.
OperatingSystem os = Environment.OSVersion;
//returns the platform id as an enumeration, in my case it's Win32NT
PlatformID platform = os.Platform;			
//the currently installed service pack, Service Pack 1 in my case
string servicePack = os.ServicePack;
//the toString version of the OS, this is "Microsoft Windows NT 6.1.7601 Service Pack 1" on this PC
string version = os.VersionString;

//I have 4 processors on this PC
int processorCount = Environment.ProcessorCount;

//returns 2 logical drives: C: and D:
string[] logicalDrives = Environment.GetLogicalDrives();

//this is how to find all environmental variables of the system and iterate through them
IDictionary envVars = Environment.GetEnvironmentVariables();
foreach (string key in envVars.Keys)
{
	//e.g. the JAVA_HOME env.var is set to "C:\Progra~1\Java\jdk1.7.0_51\"
	Debug.WriteLine(string.Concat("key: ", key, ": ", envVars[key]));
}

//retrieve the current CLR version, in my case it's "4.0.30319.18444"
Version clrVersion = Environment.Version;

View all posts related to diagnostics here.

Filed under .NET, Diagnostics Tagged with ,

Using the KeyedCollection object in C# .NET

January 26, 2016 Leave a comment

The abstract generic KeyedCollection object can be used to declare which field of your custom object to use as a key in a Dictionary. It provides sort of a short-cut where you’d want to organise your objects in a Dictionary by an attribute of that object.

Let’s take the following object as an example:

public class CloudServer
{
	public string CloudProvider { get; set; }
	public string ImageId { get; set; }
	public string Size { get; set; }
}

The Image IDs are always unique so the ImageId property seems to be a good candidate for a dictionary key.

Here’s an example:

Read more of this post

Filed under .NET, C# language features, Generics Tagged with ,

Using client certificates in .NET part 5: working with client certificates in a web project

January 25, 2016 9 Comments

Introduction

In the previous post we looked at a couple pf examples on how to work with digital certificates in C# code. In particular we saw how to load certificates from a certificate store, how to search for and how to validate one.

In this post we’ll go through how to attach a client certificate to a web request and how to extract it in a .NET Web API 2 project.

Read more of this post

Filed under .NET, Security Tagged with , , , , ,

Checking whether an enum value exists by an integer reference in C#

January 22, 2016 Leave a comment

Say you have the following ShipmentOption enumeration:

public enum ShipmentOption
{
	Land,
	Sea,
	Air
}

By default each enumeration value will have an integer representation starting with 0. So 0 corresponds to Land, 1 to Sea and 2 to Air. Imagine that a method accepts the numeric value like this:

public void SendShipment(int numericShipmentType)

Then the incoming numeric parameter could be anything. How can we check whether an integer has a corresponding enumeration value?

The following code will do just that:

public void SendShipment(int numericShipmentType)
{
	if (Enum.IsDefined(typeof(ShipmentOption), numericShipmentType))
	{
		Console.WriteLine("This type is defined: {0}", (ShipmentOption)numericShipmentType);
	}
	else
	{
		throw new InvalidEnumArgumentException("ShipmentOption", numericShipmentType, typeof(ShipmentOption));
	}
}

The InvalidEnumArgumentException class is defined in the System.ComponentModel namespace.

Passing in 2 will result in the following output:

This type is defined: Air

An invalid integer argument will throw an exception:

The value of argument ‘ShipmentOption’ (5) is invalid for Enum type ‘ShipmentOption’.

View all various C# language feature related posts here.

Filed under .NET, C# language features Tagged with , ,

Using client certificates in .NET part 4: working with client certificates in code

January 21, 2016 1 Comment

Introduction

In the previous post we discussed how to install certificates into the certificate store. We looked at the tool mmc.exe and its certificate handler snap-in. We also inspected the imported certificates visually and verified that the client certificate is valid.

In this post we’ll see a couple of examples how to work with client certificates in code.

Read more of this post

Filed under .NET, Security Tagged with , , , , ,

How to redirect standard input for a .NET console application

January 20, 2016 Leave a comment

Normally .NET console applications read their input from the console through Console.ReadLine(). The user is prompted for some input, they enter some text, press enter and the console can read this input.

However, this is not the only option you have. The standard input channel can be overridden.

Read more of this post

Filed under .NET, C# language features Tagged with ,

← Older posts

Newer posts →

Elliot Balynn's Blog

A directory of wonderful thoughts

Software Engineering

Web development

Disparate Opinions

Various tidbits

chsakell's Blog

WEB APPLICATION DEVELOPMENT TUTORIALS WITH OPEN-SOURCE PROJECTS

Once Upon a Camayoc

ARCHIVED: Bite-size insight on Cyber Security for the not too technical.