how to read word document before uploading it by webpage

Question

I have excel file abc.xls and I renamed it as abc.doc using command prompt. My requirement is: I want to upload a proper doc file, but there I can only check the MIME type of the file to upload file, this is not sufficient. I want to confirm before uploading the doc file, that it is a doc and not allow users to upload abc.doc file, because it is not a doc file its a excel file.

Answer 1

Because the OP wrote it in the comments:

You are on a wrong track here, Validation should always happen on the server side, you can add additional validation on the client side, but its not required. You have to do this for a simple reason:

Clients can always circumvent client-side Validation methods because the Client is fully under their control. So even if you implement your validation method to check if its a doc or excel document, a bad user can always just send you a post request with the validation disabled and you're getting a excel document or a virus etc.

This is a core webprogramming principle: Never trust input data, you can't validate on the client only!

Secondly your validation is done much mor easily on the server. So you should upload any file (check for file extensions & size) and then validate on the server!

Answer 2

You probably need an ActiveX Object to access the file content on the client system before uploading. Checking the byte array with javascript to find whether it's a real doc might prove interesting though :-) EDIT :

function CheckWordDoc(filepath){
    var fso, f, ts, s;
    var ForReading = 1, ForWriting = 2, ForAppending = 8;
    var TristateUseDefault = -2, TristateTrue = -1, TristateFalse = 0;
    fso = new ActiveXObject("Scripting.FileSystemObject");
    f = fso.getFile(filepath);
    ts = f.OpenAsTextStream(ForReading, TristateUseDefault);
    while (!ts.AtEndOfStream) {
        s = ts.ReadLine();
        if (s.indexOf("Word.Document.8") != -1) {
            ts.Close( );
            return true;
        }
    }          
    ts.Close( );
    return false;
}

http://www.piclist.com/techref/language/asp/vbs/vbscript/jsmthopenastextstream.htm http://msdn.microsoft.com/en-us/library/hwfw5c59%28v=vs.85%29.aspx