这真让我抓狂。我的 .NET 应用程序调用存储过程以从数据库中检索存储的散列密码:
ALTER PROCEDURE [dbo].[sGetHashedPW]
-- Add the parameters for the stored procedure here
@UserName varchar(32) = N''
AS
DECLARE @ContextInfo varbinary(128)
BEGIN
SET NOCOUNT ON;
--Set Context Info for this session to Username requested
SELECT @ContextInfo = CAST(@Username AS varbinary(128));
SET CONTEXT_INFO @ContextInfo;
--Return Hashed User Password to Application
SELECT TOP 1 [Password] as PWHash FROM [dbo].[vSecurity] WHERE [UserName] = @UserName;
END
应用程序验证密码并运行第二个存储过程,该过程在表中创建一行,session
向应用程序返回一个字符串 (GUID),并设置CONTEXT_INFO
为该字符串的值。
现在,只要应用程序打开一个连接,它就会调用sSessionStart
并传递它在登录期间收到的字符串。如果连接在新会话中打开,则 proc 应该设置CONTEXT_INFO
为它传递的经过验证的字符串值:
ALTER PROCEDURE [dbo].[sStartSession]
@token varchar(128)=NULL
AS
DECLARE @GUID uniqueidentifier
BEGIN
SET NOCOUNT ON;
IF @token IS NULL --Token not passed from the application
BEGIN
BEGIN TRANSACTION;
BEGIN TRY
SELECT @GUID = personnel_token
FROM t300_Personnel INNER JOIN vSecurity ON t300_Personnel.personnel_user_name = vSecurity.UserName
WHERE personnel_user_name = CAST(CONTEXT_INFO() as varchar(128));
SET @GUID = ISNULL(@GUID,NewID());
INSERT INTO dbo.t900_UserSession
(session_token,session_dbuser,session_id)
OUTPUT CAST(@GUID as varchar(128))
SELECT @GUID, [DB_User], @@SPID
FROM t300_Personnel INNER JOIN
vSecurity ON t300_Personnel.personnel_user_name = vSecurity.UserName
WHERE [UserName] = CAST(CONTEXT_INFO() as varchar(128));
UPDATE dbo.t300_Personnel SET [personnel_token]= @GUID
WHERE [personnel_user_name] = CAST(CONTEXT_INFO() as varchar(128));
--Change Context Info to the GUID
SET CONTEXT_INFO @GUID;
END TRY
BEGIN CATCH
IF @@TRANCOUNT > 0
ROLLBACK TRANSACTION;
THROW 51000, N'Session could not be opened',1;
END CATCH
IF @@TRANCOUNT > 0
COMMIT TRANSACTION;
END
ELSE --Token was passed from the application
BEGIN
BEGIN TRY
SELECT @GUID = CAST(@token as uniqueidentifier);
INSERT INTO dbo.t900_UserSession
(session_token,session_dbuser,session_id)
SELECT @GUID, DB_User, @@SPID
FROM t300_Personnel INNER JOIN
vSecurity ON t300_Personnel.personnel_user_name = vSecurity.UserName
WHERE personnel_token = @GUID;
IF (@@ROWCOUNT = 0) --Insert failed due to invalid token
SELECT CAST('INVALID TOKEN' as varchar(128));
ELSE --New session was created
BEGIN
SET CONTEXT_INFO @GUID;
SELECT CAST(@GUID as varchar(128));
END
END TRY
BEGIN CATCH
IF (ERROR_NUMBER() = 2627) --Token is valid but session already exists
SELECT CAST(@GUID as varchar(128));
ELSE
THROW;
END CATCH
END
END
当我在 SSMS 查询会话中模拟它时,一切正常。该应用程序遇到了问题。
第一部分工作正常:
Public Sub Authenticate(username As String, password As String, connString As String)
Using oConn As New SqlConnection(connString)
'Check that connection exists and is open
oConn.Open()
If oConn.State = ConnectionState.Open Then
Dim sqlCmd As New SqlCommand("EXEC dbo.sGetHashedPW N'" & username & "'", oConn)
_pwhash = sqlCmd.ExecuteScalar
_authenticated = EncryptHash.VerifyHash(password, "SHA512", _pwhash)
If _authenticated Then
_username = username
_connString = oConn.ConnectionString
sqlCmd.CommandText = "EXEC dbo.sStartSession"
_hashToken = sqlCmd.ExecuteScalar
Else
clearVariables()
End If
End If
End Using
End Sub
此时一切CONTEXT_INFO
正常,在两个程序中都设置正确。连接现在已关闭,但应用程序具有从该sStartSession
过程返回的验证字符串。
SqlConnection
打开表单时,会创建并打开一个表单。表单运行sStartSession
,传递字符串参数:
Private Sub frmPersonnel_Load(sender As System.Object, e As System.EventArgs) Handles MyBase.Load
Me.MdiParent = frmMain
'Open the form's connection and ensure the database session is logged
oCN = New SqlConnection(currentUser.ConnectionString)
oCN.Open()
Dim sqlCmd As New SqlCommand("EXEC dbo.sStartSession '" & currentUser.Token & "'", oCN)
Dim sResult = sqlCmd.ExecuteScalar
这是有趣的事情......sResult
按预期返回字符串,但立即CONTEXT_INFO
设置为0x00000:
SELECT
[session_id], [context_info],
CAST([context_info] as uniqueidentifier) as Context,
CAST([context_info] as varchar(128)) as Context2,
[program_name]
FROM
sys.dm_exec_sessions
WHERE
[program_name] = 'this application'
啊啊啊!