FTPS Implementation for Go

Information

This implementation does not implement the full FTP/FTPS specification. Only a small subset.

Installation

go get github.com/marcobeierer/ftps

Usage

ftps := new(FTPS)

err := ftps.Connect("localhost", 21)
if err != nil {
	panic(err)
}

err = ftps.Login("username", "password")
if err != nil {
	panic(err)
}

directory, err := ftps.PrintWorkingDirectory()
if err != nil {
	panic(err)
}
log.Printf("Current working directory: %s", directory)

// Verify or keep alive an idle control connection.
if err := ftps.Noop(); err != nil {
	panic(err)
}

err = ftps.Quit()
if err != nil {
	panic(err)
}

Implicit FTPS

For servers that establish TLS immediately, commonly on port 990, use ConnectImplicit instead of Connect:

err := ftps.ConnectImplicit("localhost", 990)
if err != nil {
	panic(err)
}

Custom connections and proxies

Set Dialer to control how both the FTPS control and passive data connections are established:

ftps.Dialer = &net.Dialer{Timeout: 10 * time.Second}

Any type with a Dial(network, address string) (net.Conn, error) method can be used. This includes SOCKS dialers from golang.org/x/net/proxy.

The default timeout for connection establishment and each subsequent network operation is 30 seconds. Set Timeout to another duration when needed. Custom dialers that implement DialContext use this timeout during connection establishment; other custom dialers are responsible for their own dial timeout.

TLS verification

Server certificates are verified against the connection hostname and the system certificate pool by default. For a private certificate authority, add that authority to TLSConfig.RootCAs. Do not use InsecureSkipVerify in production.

Resource limits

Control responses, directory listings, listing lines, and files returned by RetrieveFileData have conservative default size limits. Configure MaxControlResponseSize, MaxListSize, MaxListLineSize, or MaxRetrieveSize when larger values are required. Use RetrieveWriter to download large files without buffering them in memory.

Streaming transfers

Use StoreReader and RetrieveWriter to transfer data without buffering the entire file in memory:

if err := ftps.StoreReader("remote.dat", source); err != nil {
	panic(err)
}

if err := ftps.RetrieveWriter("remote.dat", destination); err != nil {
	panic(err)
}

Testing

Run the default test suite with:

go test ./...

The tests start an in-process explicit FTPS server with temporary storage and a self-signed certificate. No external FTPS server or environment variable is required.

The github.com/fclairamb/ftpserverlib and github.com/spf13/afero dependencies are used only by the test files to provide this server and its temporary filesystem. They are not used by the FTPS client at runtime.

Credits

This work was inspired by the work of jlaffaye (https://github.com/jlaffaye/ftp) and smallfish (https://github.com/smallfish/ftp).