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‎LICENSE

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Apache License
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‎README.md

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Golang Network File Server
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===
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4-
A [WIP] implementation of the NFSv3 protocol in pure Golang.
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NFSv3 protocol implementation in pure Golang.
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Current Status:
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* Untested
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* Mounts, read-only behavior works
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* Writing/mutations not fully implemented
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Usage
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===
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The NFS server runs on a `net.Listener` to export a file system to NFS clients.
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Usage is structured similarly to many other golang network servers.
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```golang
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import (
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"github.com/go-git/go-billy/v5/memfs"
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nfs "github.com/willscott/go-nfs"
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nfshelper "github.com/willscott/go-nfs/helpers"
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)
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listener, _ := net.Listen("tcp", ":0")
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fmt.Printf("Server running at %s\n", listener.Addr())
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mem := memfs.New()
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f, err := mem.Create("hello.txt")
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f.Write([]byte("hello world"))
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f.Close()
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handler := nfshelper.NewNullAuthHandler(mem)
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cacheHelper := nfshelper.NewCachingHandler(handler)
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nfs.Serve(listener, cacheHelper)
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```
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Notes
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---
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through specific mount options. e.g.
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`mount -o port=n,mountport=n -t nfs host:/mount /localmount`
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* It's unfortunate there isn't a agnostic / standard VFS interface to structure
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the backing of the server around. The closest may be to use the interface from
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[`net/http.FileSystem`](https://github.com/golang/go/blob/go1.11.2/src/net/http/fs.go#L93)
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or to give up on being agnostic and go with [`rio`](https://github.com/polydawn/rio/blob/master/fs/interface.go).
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* This server currently uses [billy](https://github.com/go-git/go-billy/) to
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provide a file system abstraction layer. There are some edges of the NFS protocol
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which do not translate to this abstraction.
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* NFS expects access to an `inode` or equivalent unique identifier to reference
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files in a file system. These are considered opaque identifiers here, which
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means they will not work as expected in cases of hard linking.
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* The billy abstraction layer does not extend to exposing `uid` and `gid`
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ownership of files. If ownership is important to your file system, you
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will need to ensure that the `os.FileInfo` meets additional constraints.
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In particular, the `Sys()` escape hatch is queried by this library, and
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if your file system populates a [`syscall.Stat_t`](https://golang.org/pkg/syscall/#Stat_t)
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concrete struct, the ownership specified in that object will be used.
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* Relevant RFCS:
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[5531 - RPC protocol](https://tools.ietf.org/html/rfc5531),

‎example/helloworld/main.go

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package main
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import (
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"context"
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"fmt"
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"net"
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"github.com/go-git/go-billy/v5"
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"github.com/go-git/go-billy/v5/memfs"
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nfs "github.com/willscott/go-nfs"
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nfshelper "github.com/willscott/go-nfs/helpers"
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)
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// HelloWorldHandler Provides an unauthenticated simple backing of a single static file.
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type HelloWorldHandler struct {
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fs billy.Filesystem
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}
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// Mount backs Mount RPC Requests, allowing for access control policies.
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func (h *HelloWorldHandler) Mount(ctx context.Context, conn net.Conn, req nfs.MountRequest) (status nfs.MountStatus, hndl billy.Filesystem, auths []nfs.AuthFlavor) {
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status = nfs.MountStatusOk
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hndl = h.fs
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auths = []nfs.AuthFlavor{nfs.AuthFlavorNull}
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return
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}
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// FSStat provides information about a filesystem.
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func (h *HelloWorldHandler) FSStat(ctx context.Context, f billy.Filesystem, s *nfs.FSStat) error {
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return nil
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}
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// ToHandle handled by CachingHandler
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func (h *HelloWorldHandler) ToHandle(f billy.Filesystem, s []string) []byte {
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return []byte{}
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}
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// FromHandle handled by CachingHandler
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func (h *HelloWorldHandler) FromHandle([]byte) (billy.Filesystem, []string, error) {
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return nil, []string{}, nil
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}
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func main() {
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listener, err := net.Listen("tcp", ":0")
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if err != nil {
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fmt.Printf("Failed to listen: %v\n", err)
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return
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}
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handler := HelloWorldHandler{}
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fmt.Printf("Server running at %s\n", listener.Addr())
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mem := memfs.New()
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f, err := mem.Create("hello.txt")
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f.Write([]byte("hello world"))
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f.Close()
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handler.fs = mem
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cacheHelper := nfshelper.NewCachingHandler(&handler)
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handler := nfshelper.NewNullAuthHandler(mem)
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cacheHelper := nfshelper.NewCachingHandler(handler)
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nfs.Serve(listener, cacheHelper)
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}

‎helpers/nullauthhandler.go

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package helpers
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import (
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"context"
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"net"
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"github.com/go-git/go-billy/v5"
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"github.com/willscott/go-nfs"
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)
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// NewNullAuthHandler creates a handler for the provided filesystem
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func NewNullAuthHandler(fs billy.Filesystem) nfs.Handler {
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return &NullAuthHandler{fs}
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}
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// NullAuthHandler returns a NFS backing that exposes a given file system in response to all mount requests.
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type NullAuthHandler struct {
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fs billy.Filesystem
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}
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// Mount backs Mount RPC Requests, allowing for access control policies.
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func (h *NullAuthHandler) Mount(ctx context.Context, conn net.Conn, req nfs.MountRequest) (status nfs.MountStatus, hndl billy.Filesystem, auths []nfs.AuthFlavor) {
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status = nfs.MountStatusOk
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hndl = h.fs
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auths = []nfs.AuthFlavor{nfs.AuthFlavorNull}
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return
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}
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// FSStat provides information about a filesystem.
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func (h *NullAuthHandler) FSStat(ctx context.Context, f billy.Filesystem, s *nfs.FSStat) error {
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return nil
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}
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// ToHandle handled by CachingHandler
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func (h *NullAuthHandler) ToHandle(f billy.Filesystem, s []string) []byte {
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return []byte{}
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}
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// FromHandle handled by CachingHandler
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func (h *NullAuthHandler) FromHandle([]byte) (billy.Filesystem, []string, error) {
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return nil, []string{}, nil
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}

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