globaldb.cs

计算机学院网站及管理系统

using System;
using System.Text;
using System.Configuration;
using System.Runtime.InteropServices;
using System.Collections;

namespace ComputerWeb
{
	/// <summary>
	/// Summary description for GlobalDB.
	/// </summary>
	
	public enum Store {Machine = 1, User};

	public class DBConnectionString
	{
		private static readonly string _ConnectionString = ConnectionInfo.DecryptDBConnectionString(ConfigurationSettings.AppSettings["ConnectionString"]);
		
		public static string ConnectionString
		{
			get
			{
				return _ConnectionString;
			}
		}		
	}

	public class GlobalVars
	{
		public static ArrayList FilePictureID = new ArrayList();

		public static int ChannelID = 0;
	}
	
	//自定义Exception
	public class MyException:Exception
	{
		//包含系统Excepton
		public MyException(string source,string message,Exception inner):base(message,inner)
		{
			base.Source=source;
		}

		//不包含系统Exception
		public MyException(string source,string message):base(message)
		{
			base.Source=source;
		}
	}

	public sealed class CleanString 
	{
		public static string InputText(string inputString, int maxLength) 
		{			
			StringBuilder retVal = new StringBuilder();

			// check incoming parameters for null or blank string
			if ((inputString != null) && (inputString != String.Empty)) 
			{
				inputString = inputString.Trim();

				//chop the string incase the client-side max length
				//fields are bypassed to prevent buffer over-runs
				if (inputString.Length > maxLength)
					inputString = inputString.Substring(0, maxLength);

				//convert some harmful symbols incase the regular
				//expression validators are changed
				for (int i = 0; i < inputString.Length; i++) 
				{
					switch(inputString[i]) 
					{
						case '"':
							retVal.Append("&quot;");
							break;
						case '<':
							retVal.Append("&lt;");
							break;
						case '>':
							retVal.Append("&gt;");
							break;
						default:
							retVal.Append(inputString[i]);
							break;
					}
				}

				// Replace single quotes with white space
				retVal.Replace("'", " ");
			}

			return retVal.ToString();			
		}
	}
		
	public class ConnectionInfo
	{
		public static string DecryptDBConnectionString(string InputConnectionString)
		{
			if(InputConnectionString.Equals(string.Empty))
			{
				return InputConnectionString;
			}

			DataProtector dp = new DataProtector(Store.Machine);

			byte[] decryptedData = dp.Decrypt(Convert.FromBase64String(InputConnectionString ), null);
			
			return Encoding.ASCII.GetString(decryptedData);
		}

		public static string EncryptDBConnectionString(string encryptedString)
		{
			DataProtector dp = new DataProtector(Store.Machine);

			byte[] dataBytes = Encoding.ASCII.GetBytes(encryptedString);
			byte[] encryptedBytes = dp.Encrypt(dataBytes, null);

			return Convert.ToBase64String(encryptedBytes);
		}
	}

	public class DataProtector 
	{
		#region Constants
		static private IntPtr NullPtr = ((IntPtr)((int)(0)));
		private const int CRYPTPROTECT_UI_FORBIDDEN = 0x1;
		private const int CRYPTPROTECT_LOCAL_MACHINE = 0x4;
		private Store store;
		#endregion

		#region P/Invoke structures
		[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
			internal struct DATA_BLOB 
		{
			public int cbData;
			public IntPtr pbData;
		}

		[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Unicode)]
			internal struct CRYPTPROTECT_PROMPTSTRUCT 
		{
			public int cbSize;
			public int dwPromptFlags;
			public IntPtr hwndApp;
			public String szPrompt;
		}
		#endregion

		#region External methods
		[DllImport("Crypt32.dll", SetLastError=true, CharSet=CharSet.Auto)]
		private static extern bool CryptProtectData(
			ref DATA_BLOB pDataIn, 
			String szDataDescr, 
			ref DATA_BLOB pOptionalEntropy,
			IntPtr pvReserved, 
			ref CRYPTPROTECT_PROMPTSTRUCT 
			pPromptStruct, 
			int dwFlags, 
			ref DATA_BLOB pDataOut);

		[DllImport("Crypt32.dll", SetLastError=true, CharSet=CharSet.Auto)]
		private static extern bool CryptUnprotectData(
			ref DATA_BLOB pDataIn, 
			String szDataDescr, 
			ref DATA_BLOB pOptionalEntropy, 
			IntPtr pvReserved, 
			ref CRYPTPROTECT_PROMPTSTRUCT 
			pPromptStruct, 
			int dwFlags, 
			ref DATA_BLOB pDataOut);
		
		#endregion

		#region Constructor
		public DataProtector(Store tempStore) 
		{
			store = tempStore;
		}
		#endregion

		#region Public methods
		public byte[] Encrypt(byte[] plainText, byte[] optionalEntropy) 
		{
			bool retVal = false;

			DATA_BLOB plainTextBlob = new DATA_BLOB();
			DATA_BLOB cipherTextBlob = new DATA_BLOB();
			DATA_BLOB entropyBlob = new DATA_BLOB();

			CRYPTPROTECT_PROMPTSTRUCT prompt = new CRYPTPROTECT_PROMPTSTRUCT();
			InitPromptstruct(ref prompt);

			int dwFlags;
			try 
			{
				try 
				{
					int bytesSize = plainText.Length;
					plainTextBlob.pbData = Marshal.AllocHGlobal(bytesSize);
					if(IntPtr.Zero == plainTextBlob.pbData) 
					{
						throw new Exception("Unable to allocate plaintext buffer.");
					}
					plainTextBlob.cbData = bytesSize;
					Marshal.Copy(plainText, 0, plainTextBlob.pbData, bytesSize);
				}
				catch(Exception ex) 
				{
					throw new Exception("Exception marshalling data. " + ex.Message);
				}
				if(Store.Machine == store) 
				{
					//Using the machine store, should be providing entropy.
					dwFlags = CRYPTPROTECT_LOCAL_MACHINE|CRYPTPROTECT_UI_FORBIDDEN;
					//Check to see if the entropy is null
					if(null == optionalEntropy) 
					{
						//Allocate something
						optionalEntropy = new byte[0];
					}
					try 
					{
						int bytesSize = optionalEntropy.Length;
						entropyBlob.pbData = Marshal.AllocHGlobal(optionalEntropy.Length);
						if(IntPtr.Zero == entropyBlob.pbData) 
						{
							throw new Exception("Unable to allocate entropy data buffer.");
						}
						Marshal.Copy(optionalEntropy, 0, entropyBlob.pbData, bytesSize);
						entropyBlob.cbData = bytesSize;
					}
					catch(Exception ex) 
					{
						throw new Exception("Exception entropy marshalling data. " + ex.Message);
					}
				}
				else 
				{
					//Using the user store
					dwFlags = CRYPTPROTECT_UI_FORBIDDEN;
				}
				retVal = CryptProtectData( ref plainTextBlob, "", ref entropyBlob, 
					IntPtr.Zero, ref prompt, dwFlags, ref cipherTextBlob);
				if(false == retVal) 
				{
					throw new Exception("Encryption failed. ");// + GetErrorMessage(Marshal.GetLastWin32Error()));
				}
			}
			catch(Exception ex) 
			{
				throw new Exception("Exception encrypting. " + ex.Message);
			}
			byte[] cipherText = new byte[cipherTextBlob.cbData];
			Marshal.Copy(cipherTextBlob.pbData, cipherText, 0, cipherTextBlob.cbData);
			return cipherText;
		}

		public byte[] Decrypt(byte[] cipherText, byte[] optionalEntropy) 
		{
			bool retVal = false;
			DATA_BLOB plainTextBlob = new DATA_BLOB();
			DATA_BLOB cipherBlob = new DATA_BLOB();
			CRYPTPROTECT_PROMPTSTRUCT prompt = new CRYPTPROTECT_PROMPTSTRUCT();
			InitPromptstruct(ref prompt);
			try 
			{
				try 
				{
					int cipherTextSize = cipherText.Length;
					cipherBlob.pbData = Marshal.AllocHGlobal(cipherTextSize);
					if(IntPtr.Zero == cipherBlob.pbData) 
					{
						throw new Exception("Unable to allocate cipherText buffer.");
					}
					cipherBlob.cbData = cipherTextSize;
					Marshal.Copy(cipherText, 0, cipherBlob.pbData, cipherBlob.cbData);
				}
				catch(Exception ex) 
				{
					throw new Exception("Exception marshalling data. " + ex.Message);
				}
				DATA_BLOB entropyBlob = new DATA_BLOB();
				int dwFlags;
				if(Store.Machine == store) 
				{
					//Using the machine store, should be providing entropy.
					dwFlags = CRYPTPROTECT_LOCAL_MACHINE|CRYPTPROTECT_UI_FORBIDDEN;
					//Check to see if the entropy is null
					if(null == optionalEntropy) 
					{
						//Allocate something
						optionalEntropy = new byte[0];
					}
					try 
					{
						int bytesSize = optionalEntropy.Length;
						entropyBlob.pbData = Marshal.AllocHGlobal(bytesSize);
						if(IntPtr.Zero == entropyBlob.pbData) 
						{
							throw new Exception("Unable to allocate entropy buffer.");
						}
						entropyBlob.cbData = bytesSize;
						Marshal.Copy(optionalEntropy, 0, entropyBlob.pbData, bytesSize);
					}
					catch(Exception ex) 
					{
						throw new Exception("Exception entropy marshalling data. " + ex.Message);
					}
				}
				else 
				{
					//Using the user store
					dwFlags = CRYPTPROTECT_UI_FORBIDDEN;
				}
				retVal = CryptUnprotectData(ref cipherBlob, null, ref 
					entropyBlob, 
					IntPtr.Zero, ref prompt, dwFlags, 
					ref plainTextBlob);
				if(false == retVal) 
				{
					throw new Exception("Decryption failed. ");
				}
				

				if(IntPtr.Zero != cipherBlob.pbData) 
				{
					Marshal.FreeHGlobal(cipherBlob.pbData);
				}
				if(IntPtr.Zero != entropyBlob.pbData) 
				{
					Marshal.FreeHGlobal(entropyBlob.pbData);
				}
			}
			catch(Exception ex) 
			{
				throw new Exception("Exception decrypting. " + ex.Message);
			}
			byte[] plainText = new byte[plainTextBlob.cbData];
			Marshal.Copy(plainTextBlob.pbData, plainText, 0, plainTextBlob.cbData);
			return plainText;
		}
		#endregion

		#region Private methods
		private void InitPromptstruct(ref CRYPTPROTECT_PROMPTSTRUCT ps) 
		{
			ps.cbSize = Marshal.SizeOf(typeof(CRYPTPROTECT_PROMPTSTRUCT));
			ps.dwPromptFlags = 0;
			ps.hwndApp = NullPtr;
			ps.szPrompt = null;
		}
		#endregion
	}
}