Find File Type From Magic Number Of File In MVC 5

Introduction

In this article we are going to upload a document from html input & we can find the magic number of that file & from that number we can find the type of that file.

Magic Number:

• A magic number is a number embedded at or near the beginning of a file that indicates its file format (i.e. the type of file it is).
  
• This number is not visible to us.
  
• Every file has a number which represents name of file types which is hexadecimal format.
  
• In our program we will convert it into bytes and array for checking file type from.

Chart for magic number


Note: Refer chart source for file types Wikipedia.

Step 1: Create simple project in Visual Studio 2013.



Step 2: Create one controller (right click on controller folder, add, then controller).



Step 3: Now from Index action create single view (right click on action method => add view) for this action.



Step 4: Now add code for UI which will represent one input file button, one submit button & some label (to show error, success, file name, etc).

<h2>Find File Type From Magic Number of File</h2>
@using (Html.BeginForm("Index",
"File_Upload",
FormMethod.Post,
new { enctype = "multipart/form-data" }))
{
   <label for="file">Upload file :</label>
   <input type="file" name="file" id="file" /><br>
   <input type="submit" id="submit" /> <br />
   <p>Program_Errors will show here:</p>
   @ViewBag.error
   <p>You have uploaded file type is : @ViewBag.File_Type </p>
   <br />
   @ViewBag.Message
   <br />
   @ViewBag.signature
   <br />
   @ViewBag.out_put
}

Step 5: Now create another action method with same name as index & pass ttpPostedFileBase  object.

In our action we will do the following things:

 

• Will create one array in which we can store above magic number so that it will help us at the end to compare file type in switch case.
  
  
• We need to add namespace using System.IO;
  
  
• Create one folder in our solution file as “Docs” to upload a document in this folder (download code for more information).
  
  
• Substring to select first 11 characters from hexadecimal array because every file has a different magic number so I chose only three which have same characters.
  

  [HttpPost]
  
  public ActionResult Index(HttpPostedFileBase file)
  {
  
      string ext = null;
  
      string[] file_hexa_signature = {
          "38-42-50-53", "25-50-44-46", "4D-4D-00-2A", "4D-4D-00-2A"
      };
  
      try
  
      {
  
          ext = System.IO.Path.GetExtension(file.FileName).ToLower();
  
      } catch (Exception ex)
  
      {
  
          ViewBag.error = ex.Message;
  
      }
  
      if (ext == null)
  
      {
  
          ViewBag.error = "please select onlt psd, pdf, tif file types only";
  
      }
  
  
      if (file != null && file.ContentLength > 0)
  
      {
  
          string str = Path.GetFileName(file.FileName);
  
          string path = Path.Combine(Server.MapPath("~/Docs"),
  
              Path.GetFileName(file.FileName));
  
          file.SaveAs(path);
  
          BinaryReader reader = new BinaryReader(new FileStream(Convert.ToString(path), FileMode.Open, FileAccess.Read, FileShare.None));
  
          reader.BaseStream.Position = 0x0; // The offset you are reading the data from
  
          byte[] data = reader.ReadBytes(0x10); // Read 16 bytes into an array
  
          string data_as_hex = BitConverter.ToString(data);
  
          reader.Close();
  
          // substring to select first 11 characters from hexadecimal array
  
          string my = data_as_hex.Substring(0, 11);
  
          string output = null;
  
          switch (my)
  
          {
  
              case "38-42-50-53":
  
                  output = " => psd";
  
                  break;
  
              case "25-50-44-46":
  
                  output = " => pdf";
  
                  break;
  
              case "49-49-2A-00":
  
                  output = " => tif";
  
                  break;
  
              case "4D-4D-00-2A":
  
                  output = " => tif";
  
                  break;
  
              case "null":
  
                  output = "file type is not matches with array";
  
                  break;
  
          }
  
          ViewBag.Message = data_as_hex;
  
          ViewBag.signature = my;
  
          ViewBag.out_put = output;
  
      }
  
      return View();
  
  }

Step 6: Now run our program.



Step 7: Now click on browse button & select file as shown.



Step 8: After selecting file it will show the file name.



Step 9: Now click on submit query & our output will be like. the following



Summary

This article will help freshers as well as experience candidates.

Hope you enjoyed this complete article. Don’t forget to comment.