C # Gets all database servers within a local area network

Find the network:

#region 供使用API方式时使用
        [System.Runtime.InteropServices.DllImport("odbc32.dll")]
        private static extern short SQLAllocHandle(short hType, IntPtr inputHandle, out IntPtr outputHandle);

        [System.Runtime.InteropServices.DllImport("odbc32.dll")]
        private static extern short SQLSetEnvAttr(IntPtr henv, int attribute, IntPtr valuePtr, int strLength);

        [System.Runtime.InteropServices.DllImport("odbc32.dll")]
        private static extern short SQLFreeHandle(short hType, IntPtr handle);

        [System.Runtime.InteropServices.DllImport("odbc32.dll", CharSet = System.Runtime.InteropServices.CharSet.Ansi)]

        private static extern short SQLBrowseConnect(IntPtr hconn, System.Text.StringBuilder inString,
            short inStringLength, System.Text.StringBuilder outString, short outStringLength,
            out short outLengthNeeded);

        private const short SQL_HANDLE_ENV = 1;
        private const short SQL_HANDLE_DBC = 2;
        private const int SQL_ATTR_ODBC_VERSION = 200;
        private const int SQL_OV_ODBC3 = 3;
        private const short SQL_SUCCESS = 0;
        private const short SQL_NEED_DATA = 99;
        private const short DEFAULT_RESULT_SIZE = 1024;

        private const string SQL_DRIVER_STR = "DRIVER=SQL SERVER";

        #endregion

        public Form1()
        {
            InitializeComponent();
        }

        /// <summary>
        /// 获取网内的数据库服务器名称
        /// </summary>
        /// <returns>服务器名称数组</returns>
        public static string[] GetLocalSqlServerNamesWithAPI()
        {
            string list = string.Empty;
            IntPtr henv = IntPtr.Zero;
            IntPtr hconn = IntPtr.Zero;
            System.Text.StringBuilder inString = new System.Text.StringBuilder(SQL_DRIVER_STR);
            System.Text.StringBuilder outString = new System.Text.StringBuilder(DEFAULT_RESULT_SIZE);
            short inStringLength = (short)inString.Length;
            short lenNeeded = 0;
            try
            {
                if (SQL_SUCCESS == SQLAllocHandle(SQL_HANDLE_ENV, henv, out henv))
                {
                    if (SQL_SUCCESS == SQLSetEnvAttr(henv, SQL_ATTR_ODBC_VERSION, (IntPtr)SQL_OV_ODBC3, 0))
                    {
                        if (SQL_SUCCESS == SQLAllocHandle(SQL_HANDLE_DBC, henv, out hconn))
                        {
                            if (SQL_NEED_DATA == SQLBrowseConnect(hconn, inString, inStringLength, outString,
                                 DEFAULT_RESULT_SIZE, out lenNeeded))
                            {
                                if (DEFAULT_RESULT_SIZE < lenNeeded)
                                {
                                    outString.Capacity = lenNeeded;
                                    if (SQL_NEED_DATA != SQLBrowseConnect(hconn, inString, inStringLength, outString,
                                         lenNeeded, out lenNeeded))
                                    {
                                        throw new ApplicationException("Unabled to aquire SQL Servers from ODBC driver.");
                                    }
                                }
                                list = outString.ToString();
                                int start = list.IndexOf("{") + 1;
                                int len = list.IndexOf("}") - start;
                                if ((start > 0) && (len > 0))
                                {
                                    list = list.Substring(start, len);
                                }
                                else
                                {
                                    list = string.Empty;
                                }
                            }
                        }
                    }
                }
            }
            catch
            {
                list = string.Empty;
            }

            finally
            {
                if (hconn != IntPtr.Zero)
                {
                    SQLFreeHandle(SQL_HANDLE_DBC, hconn);
                }

                if (henv != IntPtr.Zero)
                {
                    SQLFreeHandle(SQL_HANDLE_ENV, hconn);
                }
            }

            string[] array = null;

            if (list.Length > 0)
            {

                array = list.Split(',');

            }
            return array;
        }

        /// <summary>
        /// 获取局域网内的所有数据库服务器名称
        /// </summary>
        /// <returns>服务器名称数组</returns>
        public static string[] GetLocalSqlServerNamesWithSqlClientFactory()
        {
            DataTable dataSources = SqlClientFactory.Instance.CreateDataSourceEnumerator().GetDataSources();
            DataColumn column2 = dataSources.Columns["ServerName"];
            DataColumn column = dataSources.Columns["InstanceName"];
            DataRowCollection rows = dataSources.Rows;
            string[] array = new string[rows.Count];
            for (int i = 0; i < array.Length; i++)
            {
                string str2 = rows[i][column2] as string;
                string str = rows[i][column] as string;
                if (((str == null) || (str.Length == 0)) || ("MSSQLSERVER" == str))
                {
                    array[i] = str2;
                }
                else
                {
                    array[i] = str2 + @"\" + str;
                }
            }
            Array.Sort<string>(array);

            return array;
        }

        private void button1_Click(object sender, EventArgs e)
        {
            string[] arrystr = GetLocalSqlServerNamesWithSqlClientFactory();
            arrystr = GetLocalSqlServerNamesWithAPI();
            for (int i = 0; i < arrystr.Length; i++)
            {
                comboBox1.Items.Add(arrystr[i]);
            }

            comboBox1.SelectedIndex = 0;
        }