ASP防止图片木马上传的代码

const adTypeBinary=1 

dim jpg(1):jpg(0)=CByte(&HFF):jpg(1)=CByte(&HD8) 
dim bmp(1):bmp(0)=CByte(&H42):bmp(1)=CByte(&H4D) 
dim png(3):png(0)=CByte(&H89):png(1)=CByte(&H50):png(2)=CByte(&H4E):png(3)=CByte(&H47) 
dim gif(5):gif(0)=CByte(&H47):gif(1)=CByte(&H49):gif(2)=CByte(&H46):gif(3)=CByte(&H39):gif(4)=CByte(&H38):gif(5)=CByte(&H61) 
Response.Write CheckFileType(Server.MapPath("2.gif")) 

function CheckFileType(filename) 
on error resume next 
CheckFileType=false 
dim fstream,fileExt,stamp,i 
fileExt=mid(filename,InStrRev(filename,".")+1) 
set fstream=Server.createobject("ADODB.Stream") 
fstream.Open 
fstream.Type=adTypeBinary 
fstream.LoadFromFile filename 
fstream.position=0 
select case fileExt 
case "jpg","jpeg" 
stamp=fstream.read(2) 
for i=0 to 1 
if ascB(MidB(stamp,i+1,1))=jpg(i) then CheckFileType=true else CheckFileType=false 
next 
case "gif" 
stamp=fstream.read(6) 
for i=0 to 5 
if ascB(MidB(stamp,i+1,1))=gif(i) then CheckFileType=true else CheckFileType=false 
next 
case "png" 
stamp=fstream.read(4) 
for i=0 to 3 
if ascB(MidB(stamp,i+1,1))=png(i) then CheckFileType=true else CheckFileType=false 
next 
case "bmp" 
stamp=fstream.read(2) 
for i=0 to 1 
if ascB(MidB(stamp,i+1,1))=bmp(i) then CheckFileType=true else CheckFileType=false 
next 
end select 
fstream.Close 
set fseteam=nothing 
if err.number<>0 then CheckFileType=false 
end function 
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