ftp

package
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 Go to latest Published: Apr 24, 2024 License: MIT Imports: 17 Imported by: 0

Documentation

Overview

Package ftp - FTP VFS implementation.

Usage

Rely on github.com/c2fo/vfs/v6/backend 

  import(
	  "github.com/c2fo/vfs/v6/backend"
	  "github.com/c2fo/vfs/v6/backend/ftp"
  )

  func UseFs() error {
	  fs := backend.Backend(ftp.Scheme)
	  ...
  }

Or call directly: 

  import "github.com/c2fo/vfs/v6/backend/ftp"

  func DoSomething() {
	  fs := ftp.NewFilesystem()

	  location, err := fs.NewLocation("myuser@server.com:21", "/some/path/")
	  if err != nil {
		 #handle error
	  }
	  ...
  }

ftp can be augmented with some implementation-specific methods. Backend returns vfs.Filesystem interface so it would have to be cast as ftp.Filesystem to use them.

These methods are chainable: (*FileSystem) WithClient(client interface{}) *FileSystem (*FileSystem) WithOptions(opts vfs.Options) *FileSystem 

  func DoSomething() {

	  // cast if fs was created using backend.Backend().  Not necessary if created directly from ftp.NewFilesystem().
	  fs := backend.Backend(ftp.Scheme)
	  fs = fs.(*ftp.Filesystem)

	  // to pass specific client implementing types.Client interface (in this case, _ftp github.com/jlaffaye/ftp)
	  client, _ := _ftp.Dial("server.com:21")
	  fs = fs.WithClient(client)

	  // to pass in client options. See Options for more info.  Note that changes to Options will make nil any client.
	  // This behavior ensures that changes to settings will get applied to a newly created client.
	  fs = fs.WithOptions(
		  ftp.Options{
			  Password: "s3cr3t",
			  DisableEPSV: true,
			  Protocol: ftp.ProtocolFTPES,
			  DialTimeout: 15 * time.Second,
			  DebugWriter: os.Stdout,
		  },
	  )

	  location, err := fs.NewLocation("myuser@server.com:21", "/some/path/")
	  #handle error

	  file, err := location.NewFile("myfile.txt")
	  #handle error

	  _, err = file.Write([]byte("some text"))
	  #handle error

	  err = file.Close()
	  #handle error

  }

Note - this vfs implementation can have issues conducting simultaneous reads and writes on files created from the same filesystem. This can cause issues when attempting to use those files with functions such as io.CopyBuffer.

The provided CopyToFile and CopyToLocation functions should be used instead in these instances. 

// initialize a location using bob@ftp.acme.com
_, _ := os.Setenv("VFS_FTP_PASSWORD", "somepass")
someLocation, _ := vfssimple.NewLocation("ftp://bob@ftp.acme.com/some/path/")

// open some existing file
oldFile, _ := someLocation.NewFile("someExistingFile.txt")

// open some new file using same filesystem (same auth/host, same client connection)
newFile, _ := someLocation.NewFile("someNonExistentFile.txt")

// can't read and write simultaneously from the same client connection - will result in
// an error
written, err := io.Copy(newFile, oldFile)

// CopyToFile/CopyToLocation, however, will work as expected because we copy to an
// intermediate local file, thereby making the Read / Write to the remote files sequential.
// MoveToFile/MoveToLocation are unaffected since they essentially just an FTP "RENAME".
err := oldFile.CopyToFile(newFile)

Authentication

Authentication, by default, occurs automatically when Client() is called. Since user is part of the URI authority section (Volume), auth is handled slightly differently than other vfs backends (except SFTP).

A client is initialized lazily, meaning we only make a connection to the server at the last moment, so we are free to modify options until then. The authenticated session is closed any time WithOption() or WithClient() occurs.

## USERNAME

User may only be set in the URI authority section (Volume in vfs parlance). 

 scheme             host
 __/             ___/____  port
/  \            /        \ /\
ftp://someuser@server.com:22/path/to/file.txt
       \____________________/ \______________/
       \______/       \               \
           /     authority section    path
     username       (Volume)

ftp vfs backend defaults to "anonymous" if no username is provided in the authority, ie "ftp://service.com/".

## PASSWORD

Passwords may be passed via Options.Password or via the environmental variable *VFS_FTP_PASSWORD*. If not password is provided, default is "anonymous". Password precedence is default, env var, Options.Password, such that env var, if set, overrides default and Options.Password, if set, overrides env var.

Protocol

The ftp backend supports the following FTP protocols: FTP (unencrypted), FTPS (implicit TLS), and FTPES (explicit TLS). Protocol can be set by env var *VFS_FTP_PROTOCOL* or in Options.Protocol. Options values take precedence over env vars.

By default, FTPS and FTPS will use the following TLS configuration but can be overridden(recommended) with Options.TLSConfig: 

tlsConfig := &tls.Config{
	MinVersion:         tls.VersionTLS12,
	InsecureSkipVerify: true,
	ClientSessionCache: tls.NewLRUClientSessionCache(0),
	ServerName:         hostname,
}

See https://pkg.go.dev/crypto/tls#Config for all TLS configuration options.

Other Options

DebugWriter *io.Writer* - captures FTP command details to any writer.

DialTimeout *time.Duration - sets timeout for connecting only.

DisableEPSV bool - Extended Passive mode (EPSV) is attempted by default. Set to true to use regular Passive mode (PASV).

Index

Constants

View Source 
const (
	// ProtocolFTP signifies plain, unencrypted FTP
	ProtocolFTP = "FTP"
	// ProtocolFTPS signifies FTP over implicit TLS
	ProtocolFTPS = "FTPS"
	// ProtocolFTPES signifies FTP over explicit TLS
	ProtocolFTPES = "FTPES"
)
View Source 
const Scheme = "ftp"

Scheme defines the filesystem type.

Variables

This section is empty.

Functions

This section is empty.

Types

type File 

type File struct {
	// contains filtered or unexported fields
}

File implements vfs.File interface for FTP fs.

func (*File) Close 

func (f *File) Close() error

Close calls the underlying ftp.Response Close, if opened, and clears the internal pointer

func (*File) CopyToFile 

func (f *File) CopyToFile(file vfs.File) (err error)

CopyToFile puts the contents of File into the targetFile passed.

func (*File) CopyToLocation 

func (f *File) CopyToLocation(location vfs.Location) (vfs.File, error)

CopyToLocation creates a copy of *File, using the file's current path as the new file's path at the given location.

func (*File) Delete 

func (f *File) Delete(_ ...options.DeleteOption) error

Delete removes the remote file. Error is returned, if any.

func (*File) Exists 

func (f *File) Exists() (bool, error)

Exists returns a boolean of whether or not the file exists on the ftp server

func (*File) LastModified 

func (f *File) LastModified() (*time.Time, error)

LastModified returns the LastModified property of ftp file.

func (*File) Location 

func (f *File) Location() vfs.Location

Location returns a vfs.Location at the location of the file. IE: if file is at ftp://someuser@host.com/here/is/the/file.txt the location points to ftp://someuser@host.com/here/is/the/

func (*File) MoveToFile 

func (f *File) MoveToFile(t vfs.File) error

MoveToFile puts the contents of File into the targetFile passed using File.CopyToFile. If the copy succeeds, the source file is deleted. Any errors from the copy or delete are returned. If the given location is also ftp AND for the same user and host, the ftp Rename method is used, otherwise we'll do a an io.Copy to the destination file then delete source file.

func (*File) MoveToLocation 

func (f *File) MoveToLocation(location vfs.Location) (vfs.File, error)

MoveToLocation works by creating a new file on the target location then calling MoveToFile() on it.

func (*File) Name 

func (f *File) Name() string

Name returns the path portion of the file's path property. IE: "file.txt" of "ftp://someuser@host.com/some/path/to/file.txt

func (*File) Path 

func (f *File) Path() string

Path return the directory portion of the file's path. IE: "/path/to/" of "ftp://someuser@host.com/some/path/to/file.txt

func (*File) Read 

func (f *File) Read(p []byte) (n int, err error)

Read calls the underlying ftp.File Read.

func (*File) Seek 

func (f *File) Seek(offset int64, whence int) (int64, error)

Seek calls the underlying ftp.File Seek.

func (*File) Size 

func (f *File) Size() (uint64, error)

Size returns the size of the remote file.

func (*File) String 

func (f *File) String() string

String implement fmt.Stringer, returning the file's URI as the default string.

func (*File) Touch 

func (f *File) Touch() error

Touch creates a zero-length file on the vfs.File if no File exists. Update File's last modified timestamp. Returns error if unable to touch File.

func (*File) URI 

func (f *File) URI() string

URI returns the File's URI as a string.

func (*File) Write 

func (f *File) Write(data []byte) (res int, err error)

Write calls the underlying ftp.File Write.

type FileSystem 

type FileSystem struct {
	// contains filtered or unexported fields
}

FileSystem implements vfs.Filesystem for the FTP filesystem.

func NewFileSystem 

func NewFileSystem() *FileSystem

NewFileSystem initializer for fileSystem struct.

func (*FileSystem) Client 

func (fs *FileSystem) Client(ctx context.Context, authority utils.Authority) (types.Client, error)

Client returns the underlying ftp client, creating it, if necessary See Overview for authentication resolution

func (*FileSystem) DataConn 

func (fs *FileSystem) DataConn(ctx context.Context, authority utils.Authority, t types.OpenType, f *File) (types.DataConn, error)

Client returns the underlying ftp data connection, creating it, if necessary See Overview for authentication resolution

func (*FileSystem) Name 

func (fs *FileSystem) Name() string

Name returns "Secure File Transfer Protocol"

func (*FileSystem) NewFile 

func (fs *FileSystem) NewFile(authority, filePath string) (vfs.File, error)

NewFile function returns the FTP implementation of vfs.File.

func (*FileSystem) NewLocation 

func (fs *FileSystem) NewLocation(authority, locPath string) (vfs.Location, error)

NewLocation function returns the FTP implementation of vfs.Location.

func (*FileSystem) Retry 

func (fs *FileSystem) Retry() vfs.Retry

Retry will return the default no-op retrier. The FTP client provides its own retryer interface, and is available to override via the ftp.FileSystem Options type.

func (*FileSystem) Scheme 

func (fs *FileSystem) Scheme() string

Scheme return "ftp" as the initial part of a file URI ie: ftp://

func (*FileSystem) WithClient 

func (fs *FileSystem) WithClient(client types.Client) *FileSystem

WithClient passes in an ftp client and returns the filesystem (chainable)

func (*FileSystem) WithOptions 

func (fs *FileSystem) WithOptions(opts vfs.Options) *FileSystem

WithOptions sets options for client and returns the filesystem (chainable)

type Location 

type Location struct {
	Authority utils.Authority
	// contains filtered or unexported fields
}

Location implements the vfs.Location interface specific to ftp fs.

func (*Location) ChangeDir 

func (l *Location) ChangeDir(relativePath string) error

ChangeDir takes a relative path, and modifies the underlying Location's path. The caller is modified by this so the only return is any error. For this implementation there are no errors.

func (*Location) DeleteFile 

func (l *Location) DeleteFile(fileName string, _ ...options.DeleteOption) error

DeleteFile removes the file at fileName path.

func (*Location) Exists 

func (l *Location) Exists() (bool, error)

Exists returns true if the remote FTP directory exists.

func (*Location) FileSystem 

func (l *Location) FileSystem() vfs.FileSystem

FileSystem returns a vfs.fileSystem interface of the location's underlying fileSystem.

func (*Location) List 

func (l *Location) List() ([]string, error)

List calls FTP ReadDir to list all files in the location's path. If you have many thousands of files at the given location, this could become quite expensive.

func (*Location) ListByPrefix 

func (l *Location) ListByPrefix(prefix string) ([]string, error)

ListByPrefix calls FTP ReadDir with the location's path modified relatively by the prefix arg passed to the function.

  • Returns ([]string{}, nil) in the case of a non-existent directory/prefix/location.
  • "relative" prefixes are allowed, ie, listByPrefix from "/some/path/" with prefix "to/somepattern" is the same as location "/some/path/to/" with prefix of "somepattern"
  • If the user cares about the distinction between an empty location and a non-existent one, Location.Exists() should be checked first.

func (*Location) ListByRegex 

func (l *Location) ListByRegex(regex *regexp.Regexp) ([]string, error)

ListByRegex retrieves the filenames of all the files at the location's current path, then filters out all those that don't match the given regex. The resource considerations of List() apply here as well.

func (*Location) NewFile 

func (l *Location) NewFile(filePath string) (vfs.File, error)

NewFile uses the properties of the calling location to generate a vfs.File (backed by an ftp.File). The filePath argument is expected to be a relative path to the location's current path.

func (*Location) NewLocation 

func (l *Location) NewLocation(relativePath string) (vfs.Location, error)

NewLocation makes a copy of the underlying Location, then modifies its path by calling ChangeDir with the relativePath argument, returning the resulting location. The only possible errors come from the call to ChangeDir, which, for the FTP implementation doesn't ever result in an error.

func (*Location) Path 

func (l *Location) Path() string

Path returns the path the location references in most FTP calls.

func (*Location) String 

func (l *Location) String() string

String implement fmt.Stringer, returning the location's URI as the default string.

func (*Location) URI 

func (l *Location) URI() string

URI returns the Location's URI as a string.

func (*Location) Volume 

func (l *Location) Volume() string

Volume returns the Authority the location is contained in.

type Options 

type Options struct {
	Password    string // env var VFS_FTP_PASSWORD
	Protocol    string // env var VFS_FTP_PROTOCOL
	DisableEPSV *bool  // env var VFS_DISABLE_EPSV
	DebugWriter io.Writer
	TLSConfig   *tls.Config
	DialTimeout time.Duration
}

Options struct implements the vfs.Options interface, providing optional parameters for creating and ftp filesystem.

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