ASP安全检测与过滤函数SafeCheck

'作用:安全字符串检测函数
'名字:SafeCheck
'参数:CheckString,CheckType,CheckLength
'说明:
'Checkstring待检测字符串:任意字符.
'CheckType检测类型0正常短字符1数字2日期3金钱4编码HTML5解码HTML6登录字符串7防攻击检测
'CheckLength检测类型长度:类型为int,当为金钱时为小数点的位置
'返回值:如果通过检测,返回正确字符串,
'如果未通过则返回错误代码SYSTEM_ERROR ERROR_CODE
'Script Writen by :SnowDu(杜雪.NET)
'Web:http://www.snsites.com/
'Web:http://www.knowsky.com/
'-------------------------------------------
function  SafeCheck(CheckString,CheckType,CheckLength)
On Error Resume Next
ErrorRoot="SYSTEM_ERROR "
if checkString="" then
 SafeCheck=ErrorRoot&"00001"
 exit function
end if

CheckString=Replace(CheckString,"'","&#39")
select case CheckType
case 0
 CheckString=trim(CheckString)
 SafeCheck=Left(CheckString,CheckLength)
case 1
 if not isnumberic(CheckString) then
  SafeCheck=ErrorRoot&"00002"
  exit function
 else
  SafeCheck=Left(CheckString,CheckLength)
 end if
case 2
 tempVar=IsDate(CheckString)
 if Not TempVar then
  SafeCheck=ErrorRoot&"00003"
  exit function
 else
  select case CheckLength
  case 0
   SafeCheck=FormatDateTime(CheckString,vbShortDate)
  case 1
   SafeCheck=FormatDateTime(CheckString,vbLongDate)
  case 2
   SafeCheck=CheckString
  end select
 end if
case 3
 tempVar=FormatCurrency(CheckString,0)
 if Err then
  SafeCheck=ErrorRoot&"00004"
  exit function
 else
  SafeCheck=FormatCurrency(CheckString,CheckLength)
 end if
case 4
 sTemp = CheckString
 If IsNull(sTemp) = True Then
  SafeCheck=ErrorRoot&"00005"
  Exit Function
 End If
 sTemp = Replace(sTemp, "&", "&")
 sTemp = Replace(sTemp, "<", "&lt;")
 sTemp = Replace(sTemp, ">", "&gt;")
 sTemp = Replace(sTemp, Chr(34), "&quot;")
 sTemp = Replace(sTemp, Chr(10), "<br>")
 SafeCheck = Left(sTemp,CheckLength)
case 5
 sTemp = CheckString
 If IsNull(sTemp) = True Then
  SafeCheck=ErrorRoot&"00006"
  Exit Function
 End If
 sTemp = Replace(sTemp, "&amp;", "&")
 sTemp = Replace(sTemp, "&lt;", "<")
 sTemp = Replace(sTemp, "&gt;", ">")
 sTemp = Replace(sTemp, "&quot;", Chr(34))
 sTemp = Replace(sTemp, "<br>",Chr(10))
 SafeCheck = Left(sTemp,CheckLength)
case 6
 s_BadStr = "' 　&<>?%,;:()`~!@#$^*{}[] +-=" & Chr(34) & Chr(9) & Chr(32)
 n = Len(s_BadStr)
 IsSafeStr = True
 For i = 1 To n
  If Instr(CheckString, Mid(s_BadStr, i, 1)) > 0 Then
   IsSafeStr = False
  End If
 Next
 if IsSafeStr then
  SafeCheck=left(CheckString,CheckLength)
 else
  SafeCheck=ErrorRoot&"00007"
  Exit Function
 end if
case 7
 s_Filter="net user xp_cmdshell /add select count asc char mid ' "" "
 S_Filter=S_Filter&"insert delete drop truncate from % declare -"
 S_Filters=split(S_Filter," ")
 isFound=false
 for i=0 to ubound(S_Filters)-1
  if Instr(lcase(CheckString),lcase(S_Filters(i)))<>0 then
   isFound=true
   exit for
  end if
 next
 if isFound then
  SafeCheck=ErrorRoot&"00008"
  Exit Function
 else
  SafeCheck=left(CheckString,CheckLength)
 end if
end select
end function

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