Develop Reference

Failed network error - When downloading a File

I have this code to download files:
WebClient req = new WebClient();
HttpResponse response = HttpContext.Current.Response;
string filePath = file.Path;
response.Clear();
response.ClearContent();
response.ClearHeaders();
response.Buffer = true;
response.AddHeader("Content-Disposition", "attachment; filename=\"" + _fileName + "\"");
response.ContentType = Path.GetExtension(filePath);
byte[] data = req.DownloadData(filePath);
response.BinaryWrite(data);
response.Flush();
response.Close();
Some of the variables like file.path and _fileName are from a list I created to save information from the upload control in asp.net webforms.
This download code works great on all browsers in my computer, but when I passed it to a local machine, it doesn't work at all, on firefox it downloads but I can't open the file, and on chrome it says Failed Network Error.
The files are uploaded on my C: drive, but on the machine they are uploaded on a fileshare that simulates a C: drive. I used logs to understand if he was getting the file properly, and this is what I get:
\\10.50.237.18\opt\Liferay_DATA\eforms\20180126\70edd349-8cd1-4518-a55e-d49dcadb3f7c\0eadc797-7817-4e99-b39a-35f179ec1c5d.pdf
For What I understood, the file is being upload properly. But when I'm trying to download it, it's not working. I know this is a common question, but I check several solutions and I can't seem to make it work. Could you please help me understand what the problem is? Maybe the response.header?

Restrict .xml file and .cs file from download

In one of project i saw the below code.
string FileName = Request.QueryString["filename"];
System.Web.HttpResponse response = System.Web.HttpContext.Current.Response;
response.ClearContent();
response.Clear();
response.ContentType = "application/octet-stream";
response.AddHeader("Content-Disposition", "attachment; filename=" + FileName + ";");
response.TransmitFile(Server.MapPath("~/" + FileName));
response.Flush();
response.End();
which is used to download file from server. Now if someone changes filename (like web.config) in query string manually then it downloads config file also.
So please share your knowledge how to restrict from download based on file extension.

That is usually done in IIS. But, if you wanna to it programmatically:
string[] forbiddenExtensions = new string[] {".config", ".abc", ".xml" };
FileInfo fi = new FileInfo(FileName);
if (forbiddenExtensions.Contains(fi.Extension))
{
//throw some error or something...
}

First of all, you'll have to ask yourself whether you want to write code to let users download files present on the file system. The web server itself is perfectly fine handling file downloads and preventing access to files that shouldn't be shared.
If you're sure you want to do this, for example because you want some code to run before every download, then you should look at creating a handler instead. Then the web server will still first determine permissions and whatnot, in order to prevent malicious users from downloading sensitive files, and when allowed, your code will run before the download.
That being said, you don't want to serve files for download from your web root. Instead create a dedicated directory, say, "Downloads", and host your files for download from there. Then use filename = Path.GetFileName(filename) to prevent the user from navigating outside that directory (using .. and/or \).

Could not find a part of the path error on file download

I've taken on an asp/c# web app to fix originally done by the previous developer at my workplace. The code shows a Gridview populated by results from a query showing a list of files, one column is made up of 'command fields' that when clicked download a file. Everything seems to go smoothly until it reaches the file download as it can't seem to find the file on the server. My C# really isn't strong so bear with me and if you need further info that I've missed out please do say so.
Here is the specific part of code that causes problems:
//strSuppDocName - is already declared elsewhere
string path = System.IO.Path.Combine(Server.MapPath("~/Documents/"), strSuppDocName);
if (!Directory.Exists(path)){
System.Windows.Forms.MessageBox.Show(path + " - file path doesn't exist");
}
else {
System.Net.WebClient client = new System.Net.WebClient();
Byte[] buffer = client.DownloadData(path);
if (buffer != null)
{
Response.ClearContent();
Response.ClearHeaders();
FileInfo file = new FileInfo(path);
Response.Clear();
Response.AddHeader("Content-Disposition", "Attachment;FileName:" + file.Name);
Response.AddHeader("Content-Length", file.Length.ToString());
Response.ContentType = ReturnExtension(strExtSuppDoc.ToLower());
Response.WriteFile(file.FullName);
Response.End();
}
}
What happens when I run the code is that the grid view populates okay, I click the file to download and it enters the first branch of the if statement showing the path. Before I added in the if statement it was showing the following error: "could not find a part of the path". I've tried fiddling with the path such as setting it absolutely:
string path = System.IO.Path.Combine(#"E:\web\Attestation\Documents\", strSuppDocName);
And without using the Combine method above and using standard string concatenation with '+'. Any help or guidance is most appreciated, thanks!

You're mixing a handful of technologies here. First of all, this doesn't belong in a web application:
System.Windows.Forms.MessageBox.Show(path + " - file path doesn't exist");
Web applications aren't Windows Forms applications. This won't display anything to someone using the web application, because there's no concept of a "message box" over HTTP.
More to the point, however, you're using path in two very different ways. Here:
Byte[] buffer = client.DownloadData(path);
and here:
FileInfo file = new FileInfo(path);
Is path a URL on the network or a file on the file system? It can't be both. The first line is treating it as a URL, trying to download it from a web server. The second line is treating it as a local file, trying to read it from the file system.
What is path and how are you looking to access it? If it's a URL, download it with the WebClient and stream it to the user. If it's a file, read it from the file system and stream it to the user. You can't do both at the same time.

If you are interacting with a path on a network (aka UNC path), you have to use Server.MapPath to turn a UNC path or virtual path into a physical path that .NET can understand. So anytime you're opening files, creating, updating and deleting files, opening directories and deleting directories on a network path, use Server.MapPath.
Example:
System.IO.Directory.CreateDirectory(Server.MapPath("\\server\path"));

The answer in short is that the file name was incorrect.
Strangely or mistakenly the author of the code, when uploading a given file, added an extra extension so a file would be something like 'image.png' to start off with then when uploaded would become image.png.png. Why didn't I notice this before you may ask? Simply because the whole path wasn't shown in Windows XP (don't ask why I was using XP) when viewing it through the explorer window and I dismissed this issue long before - a big mistake! After trying to find the file by typing the address of the file into the windows explorer address bar and receiving an error that the file doesn't exist, yet I could plainly see it did, a colleague looked at for the file remotely using Windows 7 and we saw that the file was shown as 'image.png.png'. Thereafter the path to the file worked correctly.

Force browser to open DOCX files in full word not Word plugin

I have a web application which lists DOCX files within a directory when the users click a link the document opens within the browser using the word plug in. Is it at all possible to force the browser to open the document in full word instead of the word plug in?
This application is running on a corporate network and i have no access to amend any settings on the machines it can only be done from the web server.
They are currently using IE6 and a browser upgrade is not due for several months.
I suspect the answer is it cant be done.

I had a similar problem. I achieve a solution using a Generic Handler.
Add a new GeneriChandler.cs to you project and in the ProcessRequest do this code:
//Search for the file by querystring or other method you did, like name.
string fileId = context.Request.QueryString["fileId"];
FileInfo file = new FileInfo("C:\\" + fileId + ".docx");
context.Response.Clear();
context.Response.AddHeader("Content-Disposition", "attachment; filename=" + file.Name);
context.Response.AddHeader("Content-Length", file.Length.ToString());
context.Response.ContentType = "application/octet-stream";
context.Response.WriteFile(file.FullName);
So if your handler is called MyHandler.ashx you can call the file in the link like that :
File 1

download file to a specific location with Response.BinaryWrite and Server.Mappath possible?

I have varbinary data associated with a file in the DB. This is the code I'm using to download this file on clicking a link -
//a is my attachment object
var r = context.Response;
r.AddHeader("Content-Disposition", "attachment; filename=" + a.FileName);
r.Charset = "";
r.ContentType = a.MIME;
r.BinaryWrite(a.Content.ToArray());
Currently, this file gets downloaded to the Downloads folder. Is there any way to create a new folder in the users system and have this file download there? I read that server.mappath can be used with r.WriteFile, but I'm not quite sure. Can this be done?

No, this is not possible. Otherwise, people could maliciously write all manner of files into specific system directories. Once you send the file down to the user, the control is now out of your hands.