[bug] Can't open or download files in subfolder using FTP

[velicanu]

[bug] Can't open or download files in subfolder using FTP

[mickael-kerjean]

That's interesting, what server are you using for this? Can you send me some test credentials I could use to replicate what you're getting on your side? This is a case of a FTP server I've never seen yet, it seems that somehow you're FTP server always say everything is going well but when queries it says there's nothing in this folder.

[velicanu]

I'm using a docker based ftp server, delfer/alpine-ftp-server . I don't have a URL for you to test this on, but if you do docker-compose up with the following docker-compose.yaml file you should be able to reproduce this locally:

version: "2"
services:
  app:
    container_name: filestash
    image: machines/filestash
    restart: always
    ports:
      - "8334:8334"
    volumes:
      - ./state/:/app/data/state/

  demo:
    image: delfer/alpine-ftp-server
    environment:
      - USERS=demo|foobar
    container_name: demo
    restart: always
    volumes:
      - ./demo:/ftp/demo

Login credentials:

[vbochetRTE]

I noticed the same strange behaviour. In fact, it is even stranger than what @velicanu describes in the original post: as stated above, you can't read/download a file located in a subfolder on your FTP server except if there is a file with the same name located in the current directory of your FTP user (which in the case of filestash looks to be the home directory). There is no need that the file is the same, just it has to have the same name.

After many hours of investigations, it seems that the problem comes from FTP's LIST command itself, as I also replicated the strange behaviour only using FTP command lines.

Maybe the solution would be to change the way you check the existence of the file at the beginning of the Cat method: perform a ReadDir in the parent folder and check if it contains a file with corresponding filename, instead of using Stat method.

I tried this on my side and it seems to work. I add in my message below the code I used to test my solution, but it may not be well written according to Go standards, as I never coded in Go before.

@mickael-kerjean Please let me know if you think my solution is good and if you want me to open a PR or if you implement the solution yourself. 🙂

func (f Ftp) Cat(path string) (reader io.ReadCloser, err error) {
	fileExists := false
	f.Execute(func(client *goftp.Client) error {
		slashLastIndex := strings.LastIndex(path, "/") // split the path to get the parent path on one side and the filename on the other side
		parentPath := path[0:slashLastIndex]
		filename := path[slashLastIndex+1:]
		var fileInfos []os.FileInfo
		fileInfos, err = client.ReadDir(parentPath) // get the content of the parent folder
		if err != nil {
			return err
		} else {
			for _, fileInfo := range fileInfos { // check if a file in the parent folder matches the name of the file we want to read
				fileExists = fileExists || fileInfo.Name() == filename
			}
		}

		if fileExists { // if the file exists, read it
			pr, pw := io.Pipe()
			go func() {
				err = client.Retrieve(path, pw)
				if err != nil {
					pr.CloseWithError(NewError("Problem", 409))
				}
				pw.Close()
			}()
			reader = pr
		}

		return nil
	})

	if reader == nil { // if we couldn't find the file, return an error
		err = NewError(fmt.Sprintf("No file matches path %s", path), 404)
	}

	return reader, err
}