tailfs: clean up naming and package structure
- Restyles tailfs -> tailFS - Defines interfaces for main TailFS types - Moves implemenatation of TailFS into tailfsimpl package Updates tailscale/corp#16827 Signed-off-by: Percy Wegmann <percy@tailscale.com>
This commit is contained in:
Percy Wegmann
committed by
Percy Wegmann
Percy Wegmann
parent
79b547804b
commit
abab0d4197
359
tailfs/tailfsimpl/remote_impl.go
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359
tailfs/tailfsimpl/remote_impl.go
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@ -0,0 +1,359 @@
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// Copyright (c) Tailscale Inc & AUTHORS
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// SPDX-License-Identifier: BSD-3-Clause
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package tailfsimpl
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import (
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"bufio"
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"encoding/hex"
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"fmt"
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"log"
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"math"
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"net"
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"net/http"
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"net/netip"
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"os"
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"os/exec"
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"strings"
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"sync"
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"time"
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"github.com/tailscale/xnet/webdav"
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"tailscale.com/safesocket"
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"tailscale.com/tailfs"
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"tailscale.com/tailfs/tailfsimpl/compositefs"
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"tailscale.com/tailfs/tailfsimpl/shared"
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"tailscale.com/tailfs/tailfsimpl/webdavfs"
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"tailscale.com/types/logger"
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)
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func NewFileSystemForRemote(logf logger.Logf) *FileSystemForRemote {
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if logf == nil {
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logf = log.Printf
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}
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fs := &FileSystemForRemote{
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logf: logf,
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lockSystem: webdav.NewMemLS(),
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fileSystems: make(map[string]webdav.FileSystem),
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userServers: make(map[string]*userServer),
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}
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return fs
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}
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// FileSystemForRemote implements tailfs.FileSystemForRemote.
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type FileSystemForRemote struct {
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logf logger.Logf
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lockSystem webdav.LockSystem
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// mu guards the below values. Acquire a write lock before updating any of
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// them, acquire a read lock before reading any of them.
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mu sync.RWMutex
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fileServerAddr string
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shares map[string]*tailfs.Share
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fileSystems map[string]webdav.FileSystem
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userServers map[string]*userServer
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}
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// SetFileServerAddr implements tailfs.FileSystemForRemote.
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func (s *FileSystemForRemote) SetFileServerAddr(addr string) {
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s.mu.Lock()
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s.fileServerAddr = addr
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s.mu.Unlock()
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}
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// SetShares implements tailfs.FileSystemForRemote.
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func (s *FileSystemForRemote) SetShares(shares map[string]*tailfs.Share) {
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userServers := make(map[string]*userServer)
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if tailfs.AllowShareAs() {
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// set up per-user server
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for _, share := range shares {
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p, found := userServers[share.As]
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if !found {
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p = &userServer{
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logf: s.logf,
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}
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userServers[share.As] = p
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}
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p.shares = append(p.shares, share)
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}
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for _, p := range userServers {
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go p.runLoop()
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}
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}
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fileSystems := make(map[string]webdav.FileSystem, len(shares))
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for _, share := range shares {
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fileSystems[share.Name] = s.buildWebDAVFS(share)
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}
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s.mu.Lock()
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s.shares = shares
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oldFileSystems := s.fileSystems
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oldUserServers := s.userServers
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s.fileSystems = fileSystems
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s.userServers = userServers
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s.mu.Unlock()
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s.stopUserServers(oldUserServers)
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s.closeFileSystems(oldFileSystems)
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}
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func (s *FileSystemForRemote) buildWebDAVFS(share *tailfs.Share) webdav.FileSystem {
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return webdavfs.New(webdavfs.Options{
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Logf: s.logf,
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URL: fmt.Sprintf("http://%v/%v", hex.EncodeToString([]byte(share.Name)), share.Name),
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Transport: &http.Transport{
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Dial: func(_, shareAddr string) (net.Conn, error) {
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shareNameHex, _, err := net.SplitHostPort(shareAddr)
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if err != nil {
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return nil, fmt.Errorf("unable to parse share address %v: %w", shareAddr, err)
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}
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// We had to encode the share name in hex to make sure it's a valid hostname
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shareNameBytes, err := hex.DecodeString(shareNameHex)
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if err != nil {
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return nil, fmt.Errorf("unable to decode share name from host %v: %v", shareNameHex, err)
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}
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shareName := string(shareNameBytes)
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s.mu.RLock()
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share, shareFound := s.shares[shareName]
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userServers := s.userServers
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fileServerAddr := s.fileServerAddr
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s.mu.RUnlock()
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if !shareFound {
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return nil, fmt.Errorf("unknown share %v", shareName)
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}
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var addr string
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if !tailfs.AllowShareAs() {
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addr = fileServerAddr
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} else {
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userServer, found := userServers[share.As]
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if found {
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userServer.mu.RLock()
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addr = userServer.addr
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userServer.mu.RUnlock()
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}
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}
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if addr == "" {
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return nil, fmt.Errorf("unable to determine address for share %v", shareName)
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}
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_, err = netip.ParseAddrPort(addr)
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if err == nil {
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// this is a regular network address, dial normally
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return net.Dial("tcp", addr)
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}
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// assume this is a safesocket address
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return safesocket.Connect(addr)
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},
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},
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StatRoot: true,
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})
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}
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// ServeHTTPWithPerms implements tailfs.FileSystemForRemote.
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func (s *FileSystemForRemote) ServeHTTPWithPerms(permissions tailfs.Permissions, w http.ResponseWriter, r *http.Request) {
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isWrite := writeMethods[r.Method]
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if isWrite {
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share := shared.CleanAndSplit(r.URL.Path)[0]
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switch permissions.For(share) {
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case tailfs.PermissionNone:
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// If we have no permissions to this share, treat it as not found
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// to avoid leaking any information about the share's existence.
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http.Error(w, "not found", http.StatusNotFound)
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return
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case tailfs.PermissionReadOnly:
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http.Error(w, "permission denied", http.StatusForbidden)
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return
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}
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}
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s.mu.RLock()
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fileSystems := s.fileSystems
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s.mu.RUnlock()
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children := make([]*compositefs.Child, 0, len(fileSystems))
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// filter out shares to which the connecting principal has no access
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for name, fs := range fileSystems {
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if permissions.For(name) == tailfs.PermissionNone {
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continue
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}
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children = append(children, &compositefs.Child{Name: name, FS: fs})
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}
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cfs := compositefs.New(
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compositefs.Options{
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Logf: s.logf,
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StatChildren: true,
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})
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cfs.SetChildren(children...)
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h := webdav.Handler{
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FileSystem: cfs,
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LockSystem: s.lockSystem,
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}
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h.ServeHTTP(w, r)
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}
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func (s *FileSystemForRemote) stopUserServers(userServers map[string]*userServer) {
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for _, server := range userServers {
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if err := server.Close(); err != nil {
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s.logf("error closing tailfs user server: %v", err)
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}
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}
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}
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func (s *FileSystemForRemote) closeFileSystems(fileSystems map[string]webdav.FileSystem) {
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for _, fs := range fileSystems {
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closer, ok := fs.(interface{ Close() error })
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if ok {
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if err := closer.Close(); err != nil {
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s.logf("error closing tailfs filesystem: %v", err)
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}
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}
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}
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}
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// Close() implements tailfs.FileSystemForRemote.
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func (s *FileSystemForRemote) Close() error {
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s.mu.Lock()
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userServers := s.userServers
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fileSystems := s.fileSystems
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s.mu.Unlock()
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s.stopUserServers(userServers)
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s.closeFileSystems(fileSystems)
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return nil
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}
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// userServer runs tailscaled serve-tailfs to serve webdav content for the
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// given Shares. All Shares are assumed to have the same Share.As, and the
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// content is served as that Share.As user.
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type userServer struct {
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logf logger.Logf
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shares []*tailfs.Share
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// mu guards the below values. Acquire a write lock before updating any of
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// them, acquire a read lock before reading any of them.
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mu sync.RWMutex
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cmd *exec.Cmd
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addr string
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closed bool
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}
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func (s *userServer) Close() error {
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s.mu.Lock()
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cmd := s.cmd
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s.closed = true
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s.mu.Unlock()
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if cmd != nil && cmd.Process != nil {
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return cmd.Process.Kill()
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}
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// not running, that's okay
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return nil
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}
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func (s *userServer) runLoop() {
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executable, err := os.Executable()
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if err != nil {
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s.logf("can't find executable: %v", err)
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return
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}
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maxSleepTime := 30 * time.Second
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consecutiveFailures := float64(0)
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var timeOfLastFailure time.Time
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for {
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s.mu.RLock()
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closed := s.closed
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s.mu.RUnlock()
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if closed {
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return
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}
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err := s.run(executable)
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now := time.Now()
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timeSinceLastFailure := now.Sub(timeOfLastFailure)
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timeOfLastFailure = now
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if timeSinceLastFailure < maxSleepTime {
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consecutiveFailures++
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} else {
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consecutiveFailures = 1
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}
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sleepTime := time.Duration(math.Pow(2, consecutiveFailures)) * time.Millisecond
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if sleepTime > maxSleepTime {
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sleepTime = maxSleepTime
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}
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s.logf("user server % v stopped with error %v, will try again in %v", executable, err, sleepTime)
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time.Sleep(sleepTime)
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}
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}
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// Run runs the executable (tailscaled). This function only works on UNIX systems,
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// but those are the only ones on which we use userServers anyway.
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func (s *userServer) run(executable string) error {
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// set up the command
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args := []string{"serve-tailfs"}
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for _, s := range s.shares {
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args = append(args, s.Name, s.Path)
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}
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allArgs := []string{"-u", s.shares[0].As, executable}
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allArgs = append(allArgs, args...)
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cmd := exec.Command("sudo", allArgs...)
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stdout, err := cmd.StdoutPipe()
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if err != nil {
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return fmt.Errorf("stdout pipe: %w", err)
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}
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defer stdout.Close()
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stderr, err := cmd.StderrPipe()
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if err != nil {
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return fmt.Errorf("stderr pipe: %w", err)
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}
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defer stderr.Close()
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err = cmd.Start()
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if err != nil {
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return fmt.Errorf("start: %w", err)
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}
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s.mu.Lock()
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s.cmd = cmd
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s.mu.Unlock()
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// read address
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stdoutScanner := bufio.NewScanner(stdout)
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stdoutScanner.Scan()
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if stdoutScanner.Err() != nil {
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return fmt.Errorf("read addr: %w", stdoutScanner.Err())
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}
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addr := stdoutScanner.Text()
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// send the rest of stdout and stderr to logger to avoid blocking
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go func() {
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for stdoutScanner.Scan() {
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s.logf("tailscaled serve-tailfs stdout: %v", stdoutScanner.Text())
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}
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}()
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stderrScanner := bufio.NewScanner(stderr)
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go func() {
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for stderrScanner.Scan() {
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s.logf("tailscaled serve-tailfs stderr: %v", stderrScanner.Text())
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}
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}()
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s.mu.Lock()
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s.addr = strings.TrimSpace(addr)
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s.mu.Unlock()
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return cmd.Wait()
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}
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var writeMethods = map[string]bool{
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"PUT": true,
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"POST": true,
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"COPY": true,
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"LOCK": true,
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"UNLOCK": true,
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"MKCOL": true,
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"MOVE": true,
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"PROPPATCH": true,
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}
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