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dotNet Library: Fraction Support

Add fraction support.

 

Known Issue:

Using an instance built by default parameterless constructor will cause exception or miscalculation. To avoid this, always use parameter-based constructors. This will not be fixed due to consideration about running speed.

 

Source code: Github

License: MIT

Nuget: SecretNest.TimerFix

Supported platform: NetCore 1, NetCore 2, NetFx 4, NetStd 1.3, NetStd 2.0

TimerFix

A replacement of NetFx Threading.Timer without cumulative error

This is a complete replacement of Threading.Timer. All methods of Threading.Timer are supported. You could use this TimerFix by simply replacing the Threading.Timer object.

Threading.Timer is encapsulated in this class.

In constructors, you could pass the interval setting value. Less the value set, more CPU time is required. Default value is 15 milliseconds.

 

Source code: Github

License: MIT

Nuget: SecretNest.TimerFix

Supported platform: NetCore 1, NetCore 2, NetFx 4, NetStd 1.3, NetStd 2.0

A way to run nearly all functions of dotNet from SQL Server

Last night, I got a case to write a function in SQL Server 2005 to support the user account and password check against Active Directory. The user requirement is quite clear:

  • Create a scalar-valued function named LDAPUserCheck;
  • Parameter @username nvarchar(MAX) for user name to check;
  • Parameter @password nvarchar(MAX) for password matching the username specified;
  • Return bit 1 if succeeded, or 0 for all other reasons.

After a digging, I found that LDAP password authentication is not supported directly by SQL Server. But SQLCLR is a way to build the native dotnet program into SQL Server. In a new created SQLCLR project in VS 2005, I realized it’s unable to add the reference System.DirectoryServices.AccountManagement, which is required by running the code for Active Directory authentication. But a Web Service is a choice.

My steps to achieve that:

1 Create and deploy a Web Service for the authentication check.

1.1 Create a Web Service project.

1.2 Add System.DirectoryServices.AccountManagement as a reference.

1.3 Add a setting DomainName as string for storing the domain name.

1.4 Add a service like this:

    public class LDAPAuthentication : System.Web.Services.WebService
    {
        static string domainName = Settings.Default.DomainName;

        [WebMethod]
        public bool Check(string userName, string password)
        {
            using (PrincipalContext pc = new PrincipalContext(ContextType.Domain, domainName))
            {
                // validate the credentials
                bool isValid = pc.ValidateCredentials(userName, password);
                return isValid;
            }
        }
    }

1.5 Deploy this service and use a application pool running by a domain user. This user should be added to IIS_WPG group in Windows Server 2003.

2 Create a SQLCLR project to call the Web Service.

2.1 Create a SQLCLR project in Visual Studio 2005.

2.2 Add a Web Service reference. It’s named as LDAP in my project.

2.3 Add a User Defined Functions.

    [Microsoft.SqlServer.Server.SqlFunction]
    public static SqlBoolean LDAPUserCheck(
        SqlString username, SqlString password)
    {
        using (LDAPAuthentication.LDAP.LDAPAuthentication service = new LDAPAuthentication.LDAP.LDAPAuthentication())
        {
            if (service.Check(username.ToString(), password.ToString()))
            {
                return SqlBoolean.True;
            }
            else
            {
                return SqlBoolean.False;
            }
        }
    }

2.4 Set Permission Level to External in Database page of project setting.

2.5 Build this project to get the dll files. In my case, these files are named LDAPAuthentication.dll and LDAPAuthentication.XmlSerializers.dll.

3 Deploy this project into SQL Server 2005.

3.1 Enable the CLR support in SQL Server 2005 by running this code:

sp_configure 'show advanced options', 1;
GO
RECONFIGURE;
GO

sp_configure 'clr enabled', 1;
GO
RECONFIGURE;
GO

sp_configure 'show advanced options', 0;
GO
RECONFIGURE;
GO

3.2 Create a database for storing this function. Or, you can use any existed database as well. In my case, I created a database “tester”.

3.3 Set trustworthy on this database by running:

ALTER DATABASE [tester] SET trustworthy ON

3.4 Copy the 2 dll files created in step 2 to this server. In my case, these are stored in C:\SQLCLR folder.

3.5 Create assemblies in SQL Server by running:

create assembly [LDAPAuthentication] from 'C:\SQLCLR\LDAPAuthentication.dll' with permission_set = external_access
create assembly [LDAPAuthentication.XmlSerializers] from 'C:\SQLCLR\LDAPAuthentication.XmlSerializers.dll' with permission_set = external_access

3.6 Create function to run the method we’ve created in VS 2005:

CREATE FUNCTION [dbo].[LDAPUserCheck](@username [nvarchar](4000), @password [nvarchar](4000))
RETURNS [bit] WITH EXECUTE AS CALLER
AS 
EXTERNAL NAME [LDAPAuthentication].[UserDefinedFunctions].[LDAPUserCheck]

Now everything is done. You can call this function like all others created by SQL. Run this for test.

select dbo.LDAPUserCheck('myusername','mypassword')

 

Solved: Why Linq Where.FirstOrDefault is faster than use FirstOrDefault with condition on an array?

Hi all.

 

Why applying “.Where(condition).FirstOrDefault()” is much faster than “.FirstOrDefault(condition) when it’s applied on an array?

20140725100245

 

Answer: While calling method Where() on an Array or a List, it’s optimized to use the enumerator of the source directly. But FirstOrDefault(), which doesn’t have this mechanism, runs the virtual method version from IEnumerator.GetEnumerator().

Special thanks to Iris Sakura.

C#: Convert a tree node and sub nodes to text

Screen Shot 2013-02-20 at 10.45.56 PM

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Windows.Forms;

namespace TreeToText
{
    class TreeToText
    {
        const string LineMid = "├─";
        const string LineLast = "└─";
        const string Line = "│  ";
        const string Space = "    ";

        /// <summary>
        /// Convert a tree node to text
        /// </summary>
        /// <param name="node">Root node to convert</param>
        /// <returns>Text</returns>
        public static string Tree2Text(TreeNode node)
        {
            if (node == null) return null;
            StringBuilder builder = new StringBuilder();
            builder.AppendLine(TreeNodeText(node));
            Tree2Text(builder, node, "");
            return builder.ToString();
        }

        static string TreeNodeText(TreeNode node)
        {
            return node.Text;
        }

        static void Tree2Text(StringBuilder builder, TreeNode parent, string prefix)
        {
            int nodesCount = parent.Nodes.Count;
            if (nodesCount == 0) return;
            int nodeMaxIndex = nodesCount - 1;
            for (int i = 0; i < nodesCount; i++)
            {
                builder.Append(prefix);
                TreeNode node = parent.Nodes[i];
                if (i != nodeMaxIndex)
                {
                    builder.Append(LineMid);
                    builder.AppendLine(TreeNodeText(node));
                    Tree2Text(builder, node, prefix + Line);
                }
                else
                {
                    builder.Append(LineLast);
                    builder.AppendLine(TreeNodeText(node));
                    Tree2Text(builder, node, prefix + Space);
                }
            }
        }
    }
}

中国IP地址段抽取工具

本工具可以将所有中国的IP v4地址段抽取出来,并按照用户给定的格式保存。
通常可以用于制作特定的路由表。

IP信息来源:每次运行时自动获取自APNIC。
运行需要:dotnet Framework 4.0

运行前,请用文本编辑器打开CNRouteExtractor.exe.config,按照注释修改其中的Format字符串。
运行时的格式:CNRouteExtractor filename
将生成filename作为目标输出文件。如不指定filename则不输出(仅测试下载与抽取)。

下载地址