nfs

package module
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 Go to latest Published: Feb 10, 2022 License: Apache-2.0 Imports: 24 Imported by: 0

README

Golang Network File Server

NFSv3 protocol implementation in pure Golang.

Current Status:

  • Minimally tested
  • Mounts, read-only and read-write support

Usage

The most interesting demo is currently in example/osview.

Start the server go run ./example/osview ..

The local folder at . will be the initial view in the mount. mutations to metadata or contents will be stored purely in memory and not written back to the OS. When run, this demo will print the port it is listening on.

The mount can be accessed using a command similar to mount -o port=<n>,mountport=<n> -t nfs localhost:/mount <mountpoint> (For Mac users)

or

mount -o port=<n>,mountport=<n>,nfsvers=3,noacl,tcp -t nfs localhost:/mount <mountpoint> (For Linux users)

API

The NFS server runs on a net.Listener to export a file system to NFS clients. Usage is structured similarly to many other golang network servers.

package main

import (
	"fmt"
	"log"
	"net"

	"github.com/go-git/go-billy/v5/memfs"
	nfs "github.com/willscott/go-nfs"
	nfshelper "github.com/willscott/go-nfs/helpers"
)

func main() {
	listener, err := net.Listen("tcp", ":0")
	panicOnErr(err, "starting TCP listener")
	fmt.Printf("Server running at %s\n", listener.Addr())
	mem := memfs.New()
	f, err := mem.Create("hello.txt")
	panicOnErr(err, "creating file")
	_, err = f.Write([]byte("hello world"))
	panicOnErr(err, "writing data")
	f.Close()
	handler := nfshelper.NewNullAuthHandler(mem)
	cacheHelper := nfshelper.NewCachingHandler(handler, 1)
	panicOnErr(nfs.Serve(listener, cacheHelper), "serving nfs")
}

func panicOnErr(err error, desc ...interface{}) {
	if err == nil {
		return
	}
	log.Println(desc...)
	log.Panicln(err)
}

Notes

  • Ports are typically determined through portmap. The need for running portmap (which is the only part that needs a privileged listening port) can be avoided through specific mount options. e.g. mount -o port=n,mountport=n -t nfs host:/mount /localmount

  • This server currently uses billy to provide a file system abstraction layer. There are some edges of the NFS protocol which do not translate to this abstraction.

    • NFS expects access to an inode or equivalent unique identifier to reference files in a file system. These are considered opaque identifiers here, which means they will not work as expected in cases of hard linking.
    • The billy abstraction layer does not extend to exposing uid and gid ownership of files. If ownership is important to your file system, you will need to ensure that the os.FileInfo meets additional constraints. In particular, the Sys() escape hatch is queried by this library, and if your file system populates a syscall.Stat_t concrete struct, the ownership specified in that object will be used.

  • Relevant RFCS: 5531 - RPC protocol, 1813 - NFSv3, 1094 - NFS

Documentation

Index

Constants

View Source 
const (
	// FSInfoPropertyLink does the FS support hard links?
	FSInfoPropertyLink = 0x0001
	// FSInfoPropertySymlink does the FS support soft links?
	FSInfoPropertySymlink = 0x0002
	// FSInfoPropertyHomogeneous does the FS need PATHCONF calls for each file
	FSInfoPropertyHomogeneous = 0x0008
	// FSInfoPropertyCanSetTime can the FS support setting access/mod times?
	FSInfoPropertyCanSetTime = 0x0010
)
View Source 
const CheckRead = 1 << 15

CheckRead is a size where - if a request to read is larger than this, the server will stat the file to learn it's actual size before allocating a buffer to read into.

View Source 
const FHSize = 64

FHSize is the maximum size of a FileHandle

View Source 
const MNTNameLen = 255

MNTNameLen is the maximum size of a mount name

View Source 
const MaxRead = 1 << 24

MaxRead is the advertised largest buffer the server is willing to read

View Source 
const MntPathLen = 1024

MntPathLen is the maximum size of a mount path

View Source 
const PathNameMax = 255

PathNameMax is the maximum length for a file name

Variables

View Source 
var (
	// ErrInputInvalid is returned when input cannot be parsed
	ErrInputInvalid = errors.New("invalid input")
	// ErrAlreadySent is returned when writing a header/status multiple times
	ErrAlreadySent = errors.New("response already started")
)

Functions

func RegisterMessageHandler 

func RegisterMessageHandler(protocol uint32, proc uint32, handler HandleFunc) error

RegisterMessageHandler registers a handler for a specific XDR procedure.

func Serve 

func Serve(l net.Listener, handler Handler) error

Serve is a singleton listener paralleling http.Serve

func WritePostOpAttrs 

func WritePostOpAttrs(writer io.Writer, post *FileAttribute) error

WritePostOpAttrs writes the `post_op_attr` representation of a files attributes

func WriteWcc 

func WriteWcc(writer io.Writer, pre *FileCacheAttribute, post *FileAttribute) error

WriteWcc writes the `wcc_data` representation of an object.

Types

type AuthError 

type AuthError struct {
	AuthStat
}

AuthError is an RPCError

func (*AuthError) Code 

func (a *AuthError) Code() ResponseCode

Code for AuthErrors is ResponseCodeAuthError

func (*AuthError) Error 

func (a *AuthError) Error() string

Error is a textual representaiton of the auth error. From the RFC

func (*AuthError) MarshalBinary 

func (a *AuthError) MarshalBinary() (data []byte, err error)

MarshalBinary sends the specific auth status

type AuthFlavor 

type AuthFlavor uint32

AuthFlavor is a form of authentication, per rfc1057 section 7.2 

const (
	AuthFlavorNull  AuthFlavor = 0
	AuthFlavorUnix  AuthFlavor = 1
	AuthFlavorShort AuthFlavor = 2
	AuthFlavorDES   AuthFlavor = 3
)

AuthFlavor Codes

type AuthStat 

type AuthStat uint32

AuthStat is an enumeration of why authentication ahs failed 

const (
	AuthStatOK AuthStat = iota
	AuthStatBadCred
	AuthStatRejectedCred
	AuthStatBadVerifier
	AuthStatRejectedVerfier
	AuthStatTooWeak
	AuthStatInvalidResponse
	AuthStatFailed
	AuthStatKerbGeneric
	AuthStatTimeExpire
	AuthStatTktFile
	AuthStatDecode
	AuthStatNetAddr
	AuthStatRPCGSSCredProblem
	AuthStatRPCGSSCTXProblem
)

AuthStat Codes

type DirOpArg 

type DirOpArg struct {
	Handle   []byte
	Filename []byte
}

DirOpArg is a common serialization used for referencing an object in a directory

type FSStat 

type FSStat struct {
	TotalSize      uint64
	FreeSize       uint64
	AvailableSize  uint64
	TotalFiles     uint64
	FreeFiles      uint64
	AvailableFiles uint64
	// CacheHint is called "invarsec" in the nfs standard
	CacheHint time.Duration
}

FSStat returns metadata about a file system

type FileAttribute 

type FileAttribute struct {
	Type                FileType
	FileMode            uint32
	Nlink               uint32
	UID                 uint32
	GID                 uint32
	Filesize            uint64
	Used                uint64
	SpecData            [2]uint32
	FSID                uint64
	Fileid              uint64
	Atime, Mtime, Ctime FileTime
}

FileAttribute holds metadata about a filesystem object

func ToFileAttribute 

func ToFileAttribute(info os.FileInfo) *FileAttribute

ToFileAttribute creates an NFS fattr3 struct from an OS.FileInfo

func (FileAttribute) AsCache 

func (f FileAttribute) AsCache() *FileCacheAttribute

AsCache provides the wcc view of the file attributes

func (*FileAttribute) Mode 

func (f *FileAttribute) Mode() os.FileMode

Mode provides the OS interpreted mode of the file attributes

type FileCacheAttribute 

type FileCacheAttribute struct {
	Filesize     uint64
	Mtime, Ctime FileTime
}

FileCacheAttribute is the subset of FileAttribute used by wcc_attr

type FileHandle 

type FileHandle []byte

FileHandle maps to a fhandle3

type FileTime 

type FileTime struct {
	Seconds  uint32
	Nseconds uint32
}

FileTime is the NFS wire time format This is equivalent to go-nfs-client/nfs.NFS3Time

func ToNFSTime 

func ToNFSTime(t time.Time) FileTime

ToNFSTime generates the nfs 64bit time format from a golang time.

func (FileTime) EqualTimespec 

func (t FileTime) EqualTimespec(sec int64, nsec int64) bool

EqualTimespec returns if this time is equal to a local time spec

func (FileTime) Native 

func (t FileTime) Native() *time.Time

Native generates a golang time from an nfs time spec

type FileType 

type FileType uint32

FileType represents a NFS File Type 

const (
	FileTypeRegular FileType = iota + 1
	FileTypeDirectory
	FileTypeBlock
	FileTypeCharacter
	FileTypeLink
	FileTypeSocket
	FileTypeFIFO
)

Enumeration of NFS FileTypes

func (FileType) String 

func (f FileType) String() string

type HandleFunc 

type HandleFunc func(ctx context.Context, w *response, userHandler Handler) error

HandleFunc represents a handler for a specific protocol message.

type Handler 

type Handler interface {
	Mount(context.Context, net.Conn, MountRequest) (MountStatus, billy.Filesystem, []AuthFlavor)

	// Change can return 'nil' if filesystem is read-only
	Change(billy.Filesystem) billy.Change

	// Fill in information about a file system's free space.
	FSStat(context.Context, billy.Filesystem, *FSStat) error

	// represent file objects as opaque references
	// Can be safely implemented via helpers/cachinghandler.
	ToHandle(fs billy.Filesystem, path []string) []byte
	FromHandle(fh []byte) (billy.Filesystem, []string, error)
	// How many handles can be safely maintained by the handler.
	HandleLimit() int
}

Handler represents the interface of the file system / vfs being exposed over NFS

type MountProcedure 

type MountProcedure uint32

MountProcedure is the valid RPC calls for the mount service. 

const (
	MountProcNull MountProcedure = iota
	MountProcMount
	MountProcDump
	MountProcUmnt
	MountProcUmntAll
	MountProcExport
)

MountProcedure Codes

func (MountProcedure) String 

func (m MountProcedure) String() string

type MountRequest 

type MountRequest struct {
	rpc.Header
	Dirpath []byte
}

MountRequest contains the format of a client request to open a mount.

type MountResponse 

type MountResponse struct {
	rpc.Header
	FileHandle
	AuthFlavors []int
}

MountResponse is the server's response with status `MountStatusOk`

type MountStatus 

type MountStatus uint32

MountStatus defines the response to the Mount Procedure 

const (
	MountStatusOk             MountStatus = 0
	MountStatusErrPerm        MountStatus = 1
	MountStatusErrNoEnt       MountStatus = 2
	MountStatusErrIO          MountStatus = 5
	MountStatusErrAcces       MountStatus = 13
	MountStatusErrNotDir      MountStatus = 20
	MountStatusErrInval       MountStatus = 22
	MountStatusErrNameTooLong MountStatus = 63
	MountStatusErrNotSupp     MountStatus = 10004
	MountStatusErrServerFault MountStatus = 10006
)

MountStatus Codes

type NFSProcedure 

type NFSProcedure uint32

NFSProcedure is the valid RPC calls for the nfs service. 

const (
	NFSProcedureNull NFSProcedure = iota
	NFSProcedureGetAttr
	NFSProcedureSetAttr
	NFSProcedureLookup
	NFSProcedureAccess
	NFSProcedureReadlink
	NFSProcedureRead
	NFSProcedureWrite
	NFSProcedureCreate
	NFSProcedureMkDir
	NFSProcedureSymlink
	NFSProcedureMkNod
	NFSProcedureRemove
	NFSProcedureRmDir
	NFSProcedureRename
	NFSProcedureLink
	NFSProcedureReadDir
	NFSProcedureReadDirPlus
	NFSProcedureFSStat
	NFSProcedureFSInfo
	NFSProcedurePathConf
	NFSProcedureCommit
)

NfsProcedure Codes

func (NFSProcedure) String 

func (n NFSProcedure) String() string

type NFSStatus 

type NFSStatus uint32

NFSStatus (nfsstat3) is a result code for nfs rpc calls 

const (
	NFSStatusOk          NFSStatus = 0
	NFSStatusPerm        NFSStatus = 1
	NFSStatusNoEnt       NFSStatus = 2
	NFSStatusIO          NFSStatus = 5
	NFSStatusNXIO        NFSStatus = 6
	NFSStatusAccess      NFSStatus = 13
	NFSStatusExist       NFSStatus = 17
	NFSStatusXDev        NFSStatus = 18
	NFSStatusNoDev       NFSStatus = 19
	NFSStatusNotDir      NFSStatus = 20
	NFSStatusIsDir       NFSStatus = 21
	NFSStatusInval       NFSStatus = 22
	NFSStatusFBig        NFSStatus = 27
	NFSStatusNoSPC       NFSStatus = 28
	NFSStatusROFS        NFSStatus = 30
	NFSStatusMlink       NFSStatus = 31
	NFSStatusNameTooLong NFSStatus = 63
	NFSStatusNotEmpty    NFSStatus = 66
	NFSStatusDQuot       NFSStatus = 69
	NFSStatusStale       NFSStatus = 70
	NFSStatusRemote      NFSStatus = 71
	NFSStatusBadHandle   NFSStatus = 10001
	NFSStatusNotSync     NFSStatus = 10002
	NFSStatusBadCookie   NFSStatus = 10003
	NFSStatusNotSupp     NFSStatus = 10004
	NFSStatusTooSmall    NFSStatus = 10005
	NFSStatusServerFault NFSStatus = 10006
	NFSStatusBadType     NFSStatus = 10007
	NFSStatusJukebox     NFSStatus = 10008
)

NFSStatus codes

func (NFSStatus) String 

func (s NFSStatus) String() string

type NFSStatusError 

type NFSStatusError struct {
	NFSStatus
	WrappedErr error
}

NFSStatusError represents an error at the NFS level.

func (*NFSStatusError) Code 

func (s *NFSStatusError) Code() ResponseCode

Code for NFS issues are successful RPC responses

func (*NFSStatusError) Error 

func (s *NFSStatusError) Error() string

Error is The wrapped error

func (*NFSStatusError) MarshalBinary 

func (s *NFSStatusError) MarshalBinary() (data []byte, err error)

MarshalBinary - The binary form of the code.

func (*NFSStatusError) Unwrap 

func (s *NFSStatusError) Unwrap() error

Unwrap unpacks wrapped errors

type RPCError 

type RPCError interface {
	// An RPCError is an `error` with this method
	Error() string
	// Code is the RPC Response code to send
	Code() ResponseCode
	// BinaryMarshaler is the on-wire representation of this error
	encoding.BinaryMarshaler
}

RPCError provides the error interface for errors thrown by procedures to be transmitted over the XDR RPC channel

type RPCMismatchError 

type RPCMismatchError struct {
	Low  uint32
	High uint32
}

RPCMismatchError is an RPCError

func (*RPCMismatchError) Code 

func (r *RPCMismatchError) Code() ResponseCode

Code for RPCMismatchError is ResponseCodeRPCMismatch

func (*RPCMismatchError) Error 

func (r *RPCMismatchError) Error() string

func (*RPCMismatchError) MarshalBinary 

func (r *RPCMismatchError) MarshalBinary() (data []byte, err error)

MarshalBinary sends the specific rpc mismatch range

type ResponseCode 

type ResponseCode uint32

ResponseCode is a combination of accept_stat and reject_stat. 

const (
	ResponseCodeSuccess ResponseCode = iota
	ResponseCodeProgUnavailable
	ResponseCodeProcUnavailable
	ResponseCodeGarbageArgs
	ResponseCodeSystemErr
	ResponseCodeRPCMismatch
	ResponseCodeAuthError
)

ResponseCode Codes

type ResponseCodeProcUnavailableError 

type ResponseCodeProcUnavailableError struct {
}

ResponseCodeProcUnavailableError is an RPCError

func (*ResponseCodeProcUnavailableError) Code 

func (r *ResponseCodeProcUnavailableError) Code() ResponseCode

Code for ResponseCodeProcUnavailableError

func (*ResponseCodeProcUnavailableError) Error 

func (r *ResponseCodeProcUnavailableError) Error() string

func (*ResponseCodeProcUnavailableError) MarshalBinary 

func (r *ResponseCodeProcUnavailableError) MarshalBinary() (data []byte, err error)

MarshalBinary - this error has no associated body

type ResponseCodeSystemError 

type ResponseCodeSystemError struct {
}

ResponseCodeSystemError is an RPCError

func (*ResponseCodeSystemError) Code 

func (r *ResponseCodeSystemError) Code() ResponseCode

Code for ResponseCodeSystemError

func (*ResponseCodeSystemError) Error 

func (r *ResponseCodeSystemError) Error() string

func (*ResponseCodeSystemError) MarshalBinary 

func (r *ResponseCodeSystemError) MarshalBinary() (data []byte, err error)

MarshalBinary - this error has no associated body

type Server 

type Server struct {
	Handler
	ID [8]byte
	context.Context
}

Server is a handle to the listening NFS server.

func (*Server) Serve 

func (s *Server) Serve(l net.Listener) error

Serve listens on the provided listener port for incoming client requests.

type SetFileAttributes 

type SetFileAttributes struct {
	SetMode  *uint32
	SetUID   *uint32
	SetGID   *uint32
	SetSize  *uint64
	SetAtime *time.Time
	SetMtime *time.Time
}

SetFileAttributes represents a command to update some metadata about a file.

func ReadSetFileAttributes 

func ReadSetFileAttributes(r io.Reader) (*SetFileAttributes, error)

ReadSetFileAttributes reads an sattr3 xdr stream into a go struct.

func (*SetFileAttributes) Apply 

func (s *SetFileAttributes) Apply(changer billy.Change, fs billy.Filesystem, file string) error

Apply uses a `Change` implementation to set defined attributes on a provided file.

func (*SetFileAttributes) Mode 

func (s *SetFileAttributes) Mode(def os.FileMode) os.FileMode

Mode returns a mode if specified or the provided default mode.

type StatusErrorWithBody 

type StatusErrorWithBody struct {
	NFSStatusError
	Body []byte
}

StatusErrorWithBody is an NFS error with a payload.

func (*StatusErrorWithBody) MarshalBinary 

func (s *StatusErrorWithBody) MarshalBinary() (data []byte, err error)

MarshalBinary provides the wire format of the error response

Source Files

View all Source files

Directories

Path Synopsis
example
helloworld
osnfs
osview

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