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 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
+// 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 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(sep))
+ for i := range parts {
+ if parts[i] == "" {
+ continue
+ }
+ fi, err := stat(strings.Join(parts[:i+1], string(sep)))
+ if err != nil {
+ return originalErr
+ }
+ if !fi.IsDir() {
+ 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) ||
- strings.Contains(name, "\x00") {
- 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 = "."
}
- f, err := os.Open(filepath.Join(dir, filepath.FromSlash(path.Clean("/"+name))))
+ fullName := filepath.Join(dir, path)
+ f, err := os.Open(fullName)
if err != nil {
- return nil, err
+ 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
}
-func dirList(w ResponseWriter, f File) {
- dirs, err := f.Readdir(-1)
+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) {
+ // 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 {
- // TODO: log err.Error() to the Server.ErrorLog, once it's possible
- // for a handler to get at its Server via the ResponseWriter. See
- // Issue 12438.
+ logf(r, "http: error reading directory: %v", err)
Error(w, "Error reading directory", StatusInternalServerError)
return
}
- sort.Sort(byName(dirs))
+ 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
// part of the URL path, and not indicate the start of a query
// string or fragment.
url := url.URL{Path: name}
- fmt.Fprintf(w, "<a href=\"./%s\">%s</a>\n", url.String(), htmlReplacer.Replace(name))
+ fmt.Fprintf(w, "<a href=\"%s\">%s</a>\n", url.String(), htmlReplacer.Replace(name))
}
fmt.Fprintf(w, "</pre>\n")
}
// ServeContent replies to the request using the content in the
// provided ReadSeeker. The main benefit of ServeContent over io.Copy
// is that it handles Range requests properly, sets the MIME type, and
-// handles If-Modified-Since requests.
+// handles If-Match, If-Unmodified-Since, If-None-Match, If-Modified-Since,
+// and If-Range requests.
//
// If the response's Content-Type header is not set, ServeContent
// first tries to deduce the type from name's file extension and,
// The content's Seek method must work: ServeContent uses
// a seek to the end of the content to determine its size.
//
-// If the caller has set w's ETag header, ServeContent uses it to
-// handle requests using If-Range and If-None-Match.
+// If the caller has set w's ETag header formatted per RFC 7232, section 2.3,
+// ServeContent uses it to handle requests using If-Match, If-None-Match, or If-Range.
//
// Note that *os.File implements the io.ReadSeeker interface.
func ServeContent(w ResponseWriter, req *Request, name string, modtime time.Time, content io.ReadSeeker) {
// content must be seeked to the beginning of the file.
// The sizeFunc is called at most once. Its error, if any, is sent in the HTTP response.
func serveContent(w ResponseWriter, r *Request, name string, modtime time.Time, sizeFunc func() (int64, error), content io.ReadSeeker) {
- if checkLastModified(w, r, modtime) {
- return
- }
- rangeReq, done := checkETag(w, r, modtime)
+ setLastModified(w, modtime)
+ done, rangeReq := checkPreconditions(w, r, modtime)
if done {
return
}
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" {
}
}
-var unixEpochTime = time.Unix(0, 0)
-
-// modtime is the modification time of the resource to be served, or IsZero().
-// return value is whether this request is now complete.
-func checkLastModified(w ResponseWriter, r *Request, modtime time.Time) bool {
- if modtime.IsZero() || modtime.Equal(unixEpochTime) {
- // If the file doesn't have a modtime (IsZero), or the modtime
- // is obviously garbage (Unix time == 0), then ignore modtimes
- // and don't process the If-Modified-Since header.
- return false
+// scanETag determines if a syntactically valid ETag is present at s. If so,
+// the ETag and remaining text after consuming ETag is returned. Otherwise,
+// it returns "", "".
+func scanETag(s string) (etag string, remain string) {
+ s = textproto.TrimString(s)
+ start := 0
+ if strings.HasPrefix(s, "W/") {
+ start = 2
}
-
- // The Date-Modified header truncates sub-second precision, so
- // use mtime < t+1s instead of mtime <= t to check for unmodified.
- if t, err := time.Parse(TimeFormat, r.Header.Get("If-Modified-Since")); err == nil && modtime.Before(t.Add(1*time.Second)) {
- h := w.Header()
- delete(h, "Content-Type")
- delete(h, "Content-Length")
- w.WriteHeader(StatusNotModified)
- return true
+ if len(s[start:]) < 2 || s[start] != '"' {
+ return "", ""
}
- w.Header().Set("Last-Modified", modtime.UTC().Format(TimeFormat))
- return false
+ // ETag is either W/"text" or "text".
+ // See RFC 7232 2.3.
+ for i := start + 1; i < len(s); i++ {
+ c := s[i]
+ switch {
+ // Character values allowed in ETags.
+ case c == 0x21 || c >= 0x23 && c <= 0x7E || c >= 0x80:
+ case c == '"':
+ return s[:i+1], s[i+1:]
+ default:
+ return "", ""
+ }
+ }
+ return "", ""
}
-// checkETag implements If-None-Match and If-Range checks.
-//
-// The ETag or modtime must have been previously set in the
-// ResponseWriter's headers. The modtime is only compared at second
-// granularity and may be the zero value to mean unknown.
-//
-// The return value is the effective request "Range" header to use and
-// whether this request is now considered done.
-func checkETag(w ResponseWriter, r *Request, modtime time.Time) (rangeReq string, done bool) {
- etag := w.Header().get("Etag")
- rangeReq = r.Header.get("Range")
-
- // Invalidate the range request if the entity doesn't match the one
- // the client was expecting.
- // "If-Range: version" means "ignore the Range: header unless version matches the
- // current file."
- // We only support ETag versions.
- // The caller must have set the ETag on the response already.
- if ir := r.Header.get("If-Range"); ir != "" && ir != etag {
- // The If-Range value is typically the ETag value, but it may also be
- // the modtime date. See golang.org/issue/8367.
- timeMatches := false
- if !modtime.IsZero() {
- if t, err := ParseTime(ir); err == nil && t.Unix() == modtime.Unix() {
- timeMatches = true
- }
+// etagStrongMatch reports whether a and b match using strong ETag comparison.
+// Assumes a and b are valid ETags.
+func etagStrongMatch(a, b string) bool {
+ return a == b && a != "" && a[0] == '"'
+}
+
+// etagWeakMatch reports whether a and b match using weak ETag comparison.
+// Assumes a and b are valid ETags.
+func etagWeakMatch(a, b string) bool {
+ return strings.TrimPrefix(a, "W/") == strings.TrimPrefix(b, "W/")
+}
+
+// condResult is the result of an HTTP request precondition check.
+// See https://tools.ietf.org/html/rfc7232 section 3.
+type condResult int
+
+const (
+ condNone condResult = iota
+ condTrue
+ condFalse
+)
+
+func checkIfMatch(w ResponseWriter, r *Request) condResult {
+ im := r.Header.Get("If-Match")
+ if im == "" {
+ return condNone
+ }
+ for {
+ im = textproto.TrimString(im)
+ if len(im) == 0 {
+ break
}
- if !timeMatches {
- rangeReq = ""
+ if im[0] == ',' {
+ im = im[1:]
+ continue
+ }
+ if im[0] == '*' {
+ return condTrue
+ }
+ etag, remain := scanETag(im)
+ if etag == "" {
+ break
+ }
+ if etagStrongMatch(etag, w.Header().get("Etag")) {
+ return condTrue
}
+ im = remain
}
- if inm := r.Header.get("If-None-Match"); inm != "" {
- // Must know ETag.
+ return condFalse
+}
+
+func checkIfUnmodifiedSince(r *Request, modtime time.Time) condResult {
+ ius := r.Header.Get("If-Unmodified-Since")
+ if ius == "" || isZeroTime(modtime) {
+ return condNone
+ }
+ t, err := ParseTime(ius)
+ if err != nil {
+ 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 {
+ inm := r.Header.get("If-None-Match")
+ if inm == "" {
+ return condNone
+ }
+ buf := inm
+ for {
+ buf = textproto.TrimString(buf)
+ if len(buf) == 0 {
+ break
+ }
+ if buf[0] == ',' {
+ buf = buf[1:]
+ continue
+ }
+ if buf[0] == '*' {
+ return condFalse
+ }
+ etag, remain := scanETag(buf)
if etag == "" {
- return rangeReq, false
+ break
+ }
+ if etagWeakMatch(etag, w.Header().get("Etag")) {
+ return condFalse
}
+ buf = remain
+ }
+ return condTrue
+}
+
+func checkIfModifiedSince(r *Request, modtime time.Time) condResult {
+ if r.Method != "GET" && r.Method != "HEAD" {
+ return condNone
+ }
+ ims := r.Header.Get("If-Modified-Since")
+ if ims == "" || isZeroTime(modtime) {
+ return condNone
+ }
+ t, err := ParseTime(ims)
+ if err != nil {
+ 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 condFalse
+ }
+ return condTrue
+}
- // TODO(bradfitz): non-GET/HEAD requests require more work:
- // sending a different status code on matches, and
- // also can't use weak cache validators (those with a "W/
- // prefix). But most users of ServeContent will be using
- // it on GET or HEAD, so only support those for now.
- if r.Method != "GET" && r.Method != "HEAD" {
- return rangeReq, false
+func checkIfRange(w ResponseWriter, r *Request, modtime time.Time) condResult {
+ if r.Method != "GET" && r.Method != "HEAD" {
+ return condNone
+ }
+ ir := r.Header.get("If-Range")
+ if ir == "" {
+ return condNone
+ }
+ etag, _ := scanETag(ir)
+ if etag != "" {
+ if etagStrongMatch(etag, w.Header().Get("Etag")) {
+ return condTrue
+ } else {
+ return condFalse
}
+ }
+ // The If-Range value is typically the ETag value, but it may also be
+ // the modtime date. See golang.org/issue/8367.
+ if modtime.IsZero() {
+ return condFalse
+ }
+ t, err := ParseTime(ir)
+ if err != nil {
+ return condFalse
+ }
+ if t.Unix() == modtime.Unix() {
+ return condTrue
+ }
+ return condFalse
+}
+
+var unixEpochTime = time.Unix(0, 0)
+
+// isZeroTime reports whether t is obviously unspecified (either zero or Unix()=0).
+func isZeroTime(t time.Time) bool {
+ return t.IsZero() || t.Equal(unixEpochTime)
+}
+
+func setLastModified(w ResponseWriter, modtime time.Time) {
+ if !isZeroTime(modtime) {
+ w.Header().Set("Last-Modified", modtime.UTC().Format(TimeFormat))
+ }
+}
+
+func writeNotModified(w ResponseWriter) {
+ // RFC 7232 section 4.1:
+ // a sender SHOULD NOT generate representation metadata other than the
+ // above listed fields unless said metadata exists for the purpose of
+ // guiding cache updates (e.g., Last-Modified might be useful if the
+ // response does not have an ETag field).
+ h := w.Header()
+ delete(h, "Content-Type")
+ delete(h, "Content-Length")
+ delete(h, "Content-Encoding")
+ if h.Get("Etag") != "" {
+ delete(h, "Last-Modified")
+ }
+ w.WriteHeader(StatusNotModified)
+}
- // TODO(bradfitz): deal with comma-separated or multiple-valued
- // list of If-None-match values. For now just handle the common
- // case of a single item.
- if inm == etag || inm == "*" {
- h := w.Header()
- delete(h, "Content-Type")
- delete(h, "Content-Length")
- w.WriteHeader(StatusNotModified)
- return "", true
+// checkPreconditions evaluates request preconditions and reports whether a precondition
+// resulted in sending StatusNotModified or StatusPreconditionFailed.
+func checkPreconditions(w ResponseWriter, r *Request, modtime time.Time) (done bool, rangeHeader string) {
+ // This function carefully follows RFC 7232 section 6.
+ ch := checkIfMatch(w, r)
+ if ch == condNone {
+ ch = checkIfUnmodifiedSince(r, modtime)
+ }
+ if ch == condFalse {
+ w.WriteHeader(StatusPreconditionFailed)
+ return true, ""
+ }
+ switch checkIfNoneMatch(w, r) {
+ case condFalse:
+ if r.Method == "GET" || r.Method == "HEAD" {
+ writeNotModified(w)
+ return true, ""
+ } else {
+ w.WriteHeader(StatusPreconditionFailed)
+ return true, ""
+ }
+ case condNone:
+ if checkIfModifiedSince(r, modtime) == condFalse {
+ writeNotModified(w)
+ return true, ""
}
}
- return rangeReq, false
+
+ rangeHeader = r.Header.get("Range")
+ if rangeHeader != "" && checkIfRange(w, r, modtime) == condFalse {
+ rangeHeader = ""
+ }
+ return false, rangeHeader
}
// name is '/'-separated, not filepath.Separator.
}
}
- // 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
}
// Still a directory? (we didn't find an index.html file)
if d.IsDir() {
- if checkLastModified(w, r, d.ModTime()) {
+ if checkIfModifiedSince(r, d.ModTime()) == condFalse {
+ writeNotModified(w)
return
}
- dirList(w, f)
+ 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 special case, ServeFile redirects any request where r.URL.Path
+// 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 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.Index(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 {
}
return
}
-
-type byName []os.FileInfo
-
-func (s byName) Len() int { return len(s) }
-func (s byName) Less(i, j int) bool { return s[i].Name() < s[j].Name() }
-func (s byName) Swap(i, j int) { s[i], s[j] = s[j], s[i] }