import (
"errors"
"fmt"
+ "internal/safefilepath"
"io"
+ "io/fs"
"mime"
"mime/multipart"
"net/textproto"
// value is a filename on the native file system, not a URL, so it is separated
// by filepath.Separator, which isn't necessarily '/'.
//
-// Note that Dir will allow access to files and directories starting with a
-// period, which could expose sensitive directories like a .git directory or
-// sensitive files like .htpasswd. To exclude files with a leading period,
-// remove the files/directories from the server or create a custom FileSystem
-// implementation.
+// Note that Dir could expose sensitive files and directories. Dir will follow
+// symlinks pointing out of the directory tree, which can be especially dangerous
+// if serving from a directory in which users are able to create arbitrary symlinks.
+// Dir will also allow access to files and directories starting with a period,
+// which could expose sensitive directories like .git or sensitive files like
+// .htpasswd. To exclude files with a leading period, remove the files/directories
+// from the server or create a custom FileSystem implementation.
//
// An empty Dir is treated as ".".
type Dir string
-// mapDirOpenError maps the provided non-nil error from opening name
+// mapOpenError maps the provided non-nil error from opening name
// to a possibly better non-nil error. In particular, it turns OS-specific errors
-// about opening files in non-directories into os.ErrNotExist. See Issue 18984.
-func mapDirOpenError(originalErr error, name string) error {
- if os.IsNotExist(originalErr) || os.IsPermission(originalErr) {
+// about opening files in non-directories into fs.ErrNotExist. See Issues 18984 and 49552.
+func mapOpenError(originalErr error, name string, sep rune, stat func(string) (fs.FileInfo, error)) error {
+ if errors.Is(originalErr, fs.ErrNotExist) || errors.Is(originalErr, fs.ErrPermission) {
return originalErr
}
- parts := strings.Split(name, string(filepath.Separator))
+ parts := strings.Split(name, string(sep))
for i := range parts {
if parts[i] == "" {
continue
}
- fi, err := os.Stat(strings.Join(parts[:i+1], string(filepath.Separator)))
+ fi, err := stat(strings.Join(parts[:i+1], string(sep)))
if err != nil {
return originalErr
}
if !fi.IsDir() {
- return os.ErrNotExist
+ return fs.ErrNotExist
}
}
return originalErr
}
+// Open implements FileSystem using os.Open, opening files for reading rooted
+// and relative to the directory d.
func (d Dir) Open(name string) (File, error) {
- if filepath.Separator != '/' && strings.ContainsRune(name, filepath.Separator) {
- return nil, errors.New("http: invalid character in file path")
+ path, err := safefilepath.FromFS(path.Clean("/" + name))
+ if err != nil {
+ return nil, errors.New("http: invalid or unsafe file path")
}
dir := string(d)
if dir == "" {
dir = "."
}
- fullName := filepath.Join(dir, filepath.FromSlash(path.Clean("/"+name)))
+ fullName := filepath.Join(dir, path)
f, err := os.Open(fullName)
if err != nil {
- return nil, mapDirOpenError(err, fullName)
+ return nil, mapOpenError(err, fullName, filepath.Separator, os.Stat)
}
return f, nil
}
// A FileSystem implements access to a collection of named files.
// The elements in a file path are separated by slash ('/', U+002F)
// characters, regardless of host operating system convention.
+// See the FileServer function to convert a FileSystem to a Handler.
+//
+// This interface predates the fs.FS interface, which can be used instead:
+// the FS adapter function converts an fs.FS to a FileSystem.
type FileSystem interface {
Open(name string) (File, error)
}
io.Closer
io.Reader
io.Seeker
- Readdir(count int) ([]os.FileInfo, error)
- Stat() (os.FileInfo, error)
+ Readdir(count int) ([]fs.FileInfo, error)
+ Stat() (fs.FileInfo, error)
+}
+
+type anyDirs interface {
+ len() int
+ name(i int) string
+ isDir(i int) bool
}
+type fileInfoDirs []fs.FileInfo
+
+func (d fileInfoDirs) len() int { return len(d) }
+func (d fileInfoDirs) isDir(i int) bool { return d[i].IsDir() }
+func (d fileInfoDirs) name(i int) string { return d[i].Name() }
+
+type dirEntryDirs []fs.DirEntry
+
+func (d dirEntryDirs) len() int { return len(d) }
+func (d dirEntryDirs) isDir(i int) bool { return d[i].IsDir() }
+func (d dirEntryDirs) name(i int) string { return d[i].Name() }
+
func dirList(w ResponseWriter, r *Request, f File) {
- dirs, err := f.Readdir(-1)
+ // Prefer to use ReadDir instead of Readdir,
+ // because the former doesn't require calling
+ // Stat on every entry of a directory on Unix.
+ var dirs anyDirs
+ var err error
+ if d, ok := f.(fs.ReadDirFile); ok {
+ var list dirEntryDirs
+ list, err = d.ReadDir(-1)
+ dirs = list
+ } else {
+ var list fileInfoDirs
+ list, err = f.Readdir(-1)
+ dirs = list
+ }
+
if err != nil {
logf(r, "http: error reading directory: %v", err)
Error(w, "Error reading directory", StatusInternalServerError)
return
}
- sort.Slice(dirs, func(i, j int) bool { return dirs[i].Name() < dirs[j].Name() })
+ sort.Slice(dirs, func(i, j int) bool { return dirs.name(i) < dirs.name(j) })
w.Header().Set("Content-Type", "text/html; charset=utf-8")
fmt.Fprintf(w, "<pre>\n")
- for _, d := range dirs {
- name := d.Name()
- if d.IsDir() {
+ for i, n := 0, dirs.len(); i < n; i++ {
+ name := dirs.name(i)
+ if dirs.isDir(i) {
name += "/"
}
// name may contain '?' or '#', which must be escaped to remain
Error(w, err.Error(), StatusInternalServerError)
return
}
+ if size < 0 {
+ // Should never happen but just to be sure
+ Error(w, "negative content size computed", StatusInternalServerError)
+ return
+ }
// handle Content-Range header.
sendSize := size
var sendContent io.Reader = content
- if size >= 0 {
- ranges, err := parseRange(rangeReq, size)
- if err != nil {
- if err == errNoOverlap {
- w.Header().Set("Content-Range", fmt.Sprintf("bytes */%d", size))
- }
- Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
- return
- }
- if sumRangesSize(ranges) > size {
- // The total number of bytes in all the ranges
- // is larger than the size of the file by
- // itself, so this is probably an attack, or a
- // dumb client. Ignore the range request.
+ ranges, err := parseRange(rangeReq, size)
+ switch err {
+ case nil:
+ case errNoOverlap:
+ if size == 0 {
+ // Some clients add a Range header to all requests to
+ // limit the size of the response. If the file is empty,
+ // ignore the range header and respond with a 200 rather
+ // than a 416.
ranges = nil
+ break
}
- switch {
- case len(ranges) == 1:
- // RFC 2616, Section 14.16:
- // "When an HTTP message includes the content of a single
- // range (for example, a response to a request for a
- // single range, or to a request for a set of ranges
- // that overlap without any holes), this content is
- // transmitted with a Content-Range header, and a
- // Content-Length header showing the number of bytes
- // actually transferred.
- // ...
- // A response to a request for a single range MUST NOT
- // be sent using the multipart/byteranges media type."
- ra := ranges[0]
- if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
- Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
- return
- }
- sendSize = ra.length
- code = StatusPartialContent
- w.Header().Set("Content-Range", ra.contentRange(size))
- case len(ranges) > 1:
- sendSize = rangesMIMESize(ranges, ctype, size)
- code = StatusPartialContent
-
- pr, pw := io.Pipe()
- mw := multipart.NewWriter(pw)
- w.Header().Set("Content-Type", "multipart/byteranges; boundary="+mw.Boundary())
- sendContent = pr
- defer pr.Close() // cause writing goroutine to fail and exit if CopyN doesn't finish.
- go func() {
- for _, ra := range ranges {
- part, err := mw.CreatePart(ra.mimeHeader(ctype, size))
- if err != nil {
- pw.CloseWithError(err)
- return
- }
- if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
- pw.CloseWithError(err)
- return
- }
- if _, err := io.CopyN(part, content, ra.length); err != nil {
- pw.CloseWithError(err)
- return
- }
- }
- mw.Close()
- pw.Close()
- }()
- }
+ w.Header().Set("Content-Range", fmt.Sprintf("bytes */%d", size))
+ fallthrough
+ default:
+ Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
+ return
+ }
- w.Header().Set("Accept-Ranges", "bytes")
- if w.Header().Get("Content-Encoding") == "" {
- w.Header().Set("Content-Length", strconv.FormatInt(sendSize, 10))
+ if sumRangesSize(ranges) > size {
+ // The total number of bytes in all the ranges
+ // is larger than the size of the file by
+ // itself, so this is probably an attack, or a
+ // dumb client. Ignore the range request.
+ ranges = nil
+ }
+ switch {
+ case len(ranges) == 1:
+ // RFC 7233, Section 4.1:
+ // "If a single part is being transferred, the server
+ // generating the 206 response MUST generate a
+ // Content-Range header field, describing what range
+ // of the selected representation is enclosed, and a
+ // payload consisting of the range.
+ // ...
+ // A server MUST NOT generate a multipart response to
+ // a request for a single range, since a client that
+ // does not request multiple parts might not support
+ // multipart responses."
+ ra := ranges[0]
+ if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
+ Error(w, err.Error(), StatusRequestedRangeNotSatisfiable)
+ return
}
+ sendSize = ra.length
+ code = StatusPartialContent
+ w.Header().Set("Content-Range", ra.contentRange(size))
+ case len(ranges) > 1:
+ sendSize = rangesMIMESize(ranges, ctype, size)
+ code = StatusPartialContent
+
+ pr, pw := io.Pipe()
+ mw := multipart.NewWriter(pw)
+ w.Header().Set("Content-Type", "multipart/byteranges; boundary="+mw.Boundary())
+ sendContent = pr
+ defer pr.Close() // cause writing goroutine to fail and exit if CopyN doesn't finish.
+ go func() {
+ for _, ra := range ranges {
+ part, err := mw.CreatePart(ra.mimeHeader(ctype, size))
+ if err != nil {
+ pw.CloseWithError(err)
+ return
+ }
+ if _, err := content.Seek(ra.start, io.SeekStart); err != nil {
+ pw.CloseWithError(err)
+ return
+ }
+ if _, err := io.CopyN(part, content, ra.length); err != nil {
+ pw.CloseWithError(err)
+ return
+ }
+ }
+ mw.Close()
+ pw.Close()
+ }()
}
+ w.Header().Set("Accept-Ranges", "bytes")
+ w.Header().Set("Content-Length", strconv.FormatInt(sendSize, 10))
+
w.WriteHeader(code)
if r.Method != "HEAD" {
if ius == "" || isZeroTime(modtime) {
return condNone
}
- if t, err := ParseTime(ius); err == nil {
- // The Date-Modified header truncates sub-second precision, so
- // use mtime < t+1s instead of mtime <= t to check for unmodified.
- if modtime.Before(t.Add(1 * time.Second)) {
- return condTrue
- }
- return condFalse
+ t, err := ParseTime(ius)
+ if err != nil {
+ return condNone
}
- return condNone
+
+ // The Last-Modified header truncates sub-second precision so
+ // the modtime needs to be truncated too.
+ modtime = modtime.Truncate(time.Second)
+ if ret := modtime.Compare(t); ret <= 0 {
+ return condTrue
+ }
+ return condFalse
}
func checkIfNoneMatch(w ResponseWriter, r *Request) condResult {
}
if buf[0] == ',' {
buf = buf[1:]
+ continue
}
if buf[0] == '*' {
return condFalse
if err != nil {
return condNone
}
- // The Date-Modified header truncates sub-second precision, so
- // use mtime < t+1s instead of mtime <= t to check for unmodified.
- if modtime.Before(t.Add(1 * time.Second)) {
+ // The Last-Modified header truncates sub-second precision so
+ // the modtime needs to be truncated too.
+ modtime = modtime.Truncate(time.Second)
+ if ret := modtime.Compare(t); ret <= 0 {
return condFalse
}
return condTrue
h := w.Header()
delete(h, "Content-Type")
delete(h, "Content-Length")
+ delete(h, "Content-Encoding")
if h.Get("Etag") != "" {
delete(h, "Last-Modified")
}
}
}
- // redirect if the directory name doesn't end in a slash
if d.IsDir() {
url := r.URL.Path
- if url[len(url)-1] != '/' {
+ // redirect if the directory name doesn't end in a slash
+ if url == "" || url[len(url)-1] != '/' {
localRedirect(w, r, path.Base(url)+"/")
return
}
- }
- // use contents of index.html for directory, if present
- if d.IsDir() {
+ // use contents of index.html for directory, if present
index := strings.TrimSuffix(name, "/") + indexPage
ff, err := fs.Open(index)
if err == nil {
defer ff.Close()
dd, err := ff.Stat()
if err == nil {
- name = index
d = dd
f = ff
}
writeNotModified(w)
return
}
- w.Header().Set("Last-Modified", d.ModTime().UTC().Format(TimeFormat))
+ setLastModified(w, d.ModTime())
dirList(w, r, f)
return
}
// and historically Go's ServeContent always returned just "404 Not Found" for
// all errors. We don't want to start leaking information in error messages.
func toHTTPError(err error) (msg string, httpStatus int) {
- if os.IsNotExist(err) {
+ if errors.Is(err, fs.ErrNotExist) {
return "404 page not found", StatusNotFound
}
- if os.IsPermission(err) {
+ if errors.Is(err, fs.ErrPermission) {
return "403 Forbidden", StatusForbidden
}
// Default:
// file or directory.
//
// If the provided file or directory name is a relative path, it is
-// interpreted relative to the current directory and may ascend to parent
-// directories. If the provided name is constructed from user input, it
-// should be sanitized before calling ServeFile. As a precaution, ServeFile
-// will reject requests where r.URL.Path contains a ".." path element.
+// interpreted relative to the current directory and may ascend to
+// parent directories. If the provided name is constructed from user
+// input, it should be sanitized before calling ServeFile.
+//
+// As a precaution, ServeFile will reject requests where r.URL.Path
+// contains a ".." path element; this protects against callers who
+// might unsafely use filepath.Join on r.URL.Path without sanitizing
+// it and then use that filepath.Join result as the name argument.
//
-// As a special case, ServeFile redirects any request where r.URL.Path
+// As another special case, ServeFile redirects any request where r.URL.Path
// ends in "/index.html" to the same path, without the final
// "index.html". To avoid such redirects either modify the path or
// use ServeContent.
+//
+// Outside of those two special cases, ServeFile does not use
+// r.URL.Path for selecting the file or directory to serve; only the
+// file or directory provided in the name argument is used.
func ServeFile(w ResponseWriter, r *Request, name string) {
if containsDotDot(r.URL.Path) {
// Too many programs use r.URL.Path to construct the argument to
serveFile(w, r, Dir(dir), file, false)
}
+// ServeFileFS replies to the request with the contents
+// of the named file or directory from the file system fsys.
+//
+// If the provided file or directory name is a relative path, it is
+// interpreted relative to the current directory and may ascend to
+// parent directories. If the provided name is constructed from user
+// input, it should be sanitized before calling ServeFile.
+//
+// As a precaution, ServeFile will reject requests where r.URL.Path
+// contains a ".." path element; this protects against callers who
+// might unsafely use filepath.Join on r.URL.Path without sanitizing
+// it and then use that filepath.Join result as the name argument.
+//
+// As another special case, ServeFile redirects any request where r.URL.Path
+// ends in "/index.html" to the same path, without the final
+// "index.html". To avoid such redirects either modify the path or
+// use ServeContent.
+//
+// Outside of those two special cases, ServeFile does not use
+// r.URL.Path for selecting the file or directory to serve; only the
+// file or directory provided in the name argument is used.
+func ServeFileFS(w ResponseWriter, r *Request, fsys fs.FS, name string) {
+ if containsDotDot(r.URL.Path) {
+ // Too many programs use r.URL.Path to construct the argument to
+ // serveFile. Reject the request under the assumption that happened
+ // here and ".." may not be wanted.
+ // Note that name might not contain "..", for example if code (still
+ // incorrectly) used filepath.Join(myDir, r.URL.Path).
+ Error(w, "invalid URL path", StatusBadRequest)
+ return
+ }
+ serveFile(w, r, FS(fsys), name, false)
+}
+
func containsDotDot(v string) bool {
if !strings.Contains(v, "..") {
return false
root FileSystem
}
+type ioFS struct {
+ fsys fs.FS
+}
+
+type ioFile struct {
+ file fs.File
+}
+
+func (f ioFS) Open(name string) (File, error) {
+ if name == "/" {
+ name = "."
+ } else {
+ name = strings.TrimPrefix(name, "/")
+ }
+ file, err := f.fsys.Open(name)
+ if err != nil {
+ return nil, mapOpenError(err, name, '/', func(path string) (fs.FileInfo, error) {
+ return fs.Stat(f.fsys, path)
+ })
+ }
+ return ioFile{file}, nil
+}
+
+func (f ioFile) Close() error { return f.file.Close() }
+func (f ioFile) Read(b []byte) (int, error) { return f.file.Read(b) }
+func (f ioFile) Stat() (fs.FileInfo, error) { return f.file.Stat() }
+
+var errMissingSeek = errors.New("io.File missing Seek method")
+var errMissingReadDir = errors.New("io.File directory missing ReadDir method")
+
+func (f ioFile) Seek(offset int64, whence int) (int64, error) {
+ s, ok := f.file.(io.Seeker)
+ if !ok {
+ return 0, errMissingSeek
+ }
+ return s.Seek(offset, whence)
+}
+
+func (f ioFile) ReadDir(count int) ([]fs.DirEntry, error) {
+ d, ok := f.file.(fs.ReadDirFile)
+ if !ok {
+ return nil, errMissingReadDir
+ }
+ return d.ReadDir(count)
+}
+
+func (f ioFile) Readdir(count int) ([]fs.FileInfo, error) {
+ d, ok := f.file.(fs.ReadDirFile)
+ if !ok {
+ return nil, errMissingReadDir
+ }
+ var list []fs.FileInfo
+ for {
+ dirs, err := d.ReadDir(count - len(list))
+ for _, dir := range dirs {
+ info, err := dir.Info()
+ if err != nil {
+ // Pretend it doesn't exist, like (*os.File).Readdir does.
+ continue
+ }
+ list = append(list, info)
+ }
+ if err != nil {
+ return list, err
+ }
+ if count < 0 || len(list) >= count {
+ break
+ }
+ }
+ return list, nil
+}
+
+// FS converts fsys to a FileSystem implementation,
+// for use with FileServer and NewFileTransport.
+// The files provided by fsys must implement io.Seeker.
+func FS(fsys fs.FS) FileSystem {
+ return ioFS{fsys}
+}
+
// FileServer returns a handler that serves HTTP requests
// with the contents of the file system rooted at root.
//
+// As a special case, the returned file server redirects any request
+// ending in "/index.html" to the same path, without the final
+// "index.html".
+//
// To use the operating system's file system implementation,
// use http.Dir:
//
-// http.Handle("/", http.FileServer(http.Dir("/tmp")))
+// http.Handle("/", http.FileServer(http.Dir("/tmp")))
+//
+// To use an fs.FS implementation, use http.FileServerFS instead.
+func FileServer(root FileSystem) Handler {
+ return &fileHandler{root}
+}
+
+// FileServerFS returns a handler that serves HTTP requests
+// with the contents of the file system fsys.
//
// As a special case, the returned file server redirects any request
// ending in "/index.html" to the same path, without the final
// "index.html".
-func FileServer(root FileSystem) Handler {
- return &fileHandler{root}
+//
+// http.Handle("/", http.FileServerFS(fsys))
+func FileServerFS(root fs.FS) Handler {
+ return FileServer(FS(root))
}
func (f *fileHandler) ServeHTTP(w ResponseWriter, r *Request) {
}
}
-// parseRange parses a Range header string as per RFC 2616.
+// parseRange parses a Range header string as per RFC 7233.
// errNoOverlap is returned if none of the ranges overlap.
func parseRange(s string, size int64) ([]httpRange, error) {
if s == "" {
var ranges []httpRange
noOverlap := false
for _, ra := range strings.Split(s[len(b):], ",") {
- ra = strings.TrimSpace(ra)
+ ra = textproto.TrimString(ra)
if ra == "" {
continue
}
- i := strings.IndexByte(ra, '-')
- if i < 0 {
+ start, end, ok := strings.Cut(ra, "-")
+ if !ok {
return nil, errors.New("invalid range")
}
- start, end := strings.TrimSpace(ra[:i]), strings.TrimSpace(ra[i+1:])
+ start, end = textproto.TrimString(start), textproto.TrimString(end)
var r httpRange
if start == "" {
// If no start is specified, end specifies the
- // range start relative to the end of the file.
+ // range start relative to the end of the file,
+ // and we are dealing with <suffix-length>
+ // which has to be a non-negative integer as per
+ // RFC 7233 Section 2.1 "Byte-Ranges".
+ if end == "" || end[0] == '-' {
+ return nil, errors.New("invalid range")
+ }
i, err := strconv.ParseInt(end, 10, 64)
- if err != nil {
+ if i < 0 || err != nil {
return nil, errors.New("invalid range")
}
if i > size {