| // Copyright 2009 The Go Authors. All rights reserved. |
| // Use of this source code is governed by a BSD-style |
| // license that can be found in the LICENSE file. |
| |
| // HTTP file system request handler |
| |
| package http |
| |
| import ( |
| "errors" |
| "fmt" |
| "io" |
| "mime" |
| "mime/multipart" |
| "net/textproto" |
| "net/url" |
| "os" |
| "path" |
| "path/filepath" |
| "sort" |
| "strconv" |
| "strings" |
| "time" |
| ) |
| |
| // A Dir implements FileSystem using the native file system restricted to a |
| // specific directory tree. |
| // |
| // While the FileSystem.Open method takes '/'-separated paths, a Dir's string |
| // value is a filename on the native file system, not a URL, so it is separated |
| // by filepath.Separator, which isn't necessarily '/'. |
| // |
| // An empty Dir is treated as ".". |
| type Dir string |
| |
| func (d Dir) Open(name string) (File, error) { |
| if filepath.Separator != '/' && strings.IndexRune(name, filepath.Separator) >= 0 || |
| strings.Contains(name, "\x00") { |
| return nil, errors.New("http: invalid character in file path") |
| } |
| dir := string(d) |
| if dir == "" { |
| dir = "." |
| } |
| f, err := os.Open(filepath.Join(dir, filepath.FromSlash(path.Clean("/"+name)))) |
| if err != nil { |
| return nil, err |
| } |
| 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. |
| type FileSystem interface { |
| Open(name string) (File, error) |
| } |
| |
| // A File is returned by a FileSystem's Open method and can be |
| // served by the FileServer implementation. |
| // |
| // The methods should behave the same as those on an *os.File. |
| type File interface { |
| io.Closer |
| io.Reader |
| io.Seeker |
| Readdir(count int) ([]os.FileInfo, error) |
| Stat() (os.FileInfo, error) |
| } |
| |
| func dirList(w ResponseWriter, f File) { |
| dirs, err := f.Readdir(-1) |
| 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. |
| Error(w, "Error reading directory", StatusInternalServerError) |
| return |
| } |
| sort.Sort(byName(dirs)) |
| |
| 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() { |
| 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, "</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. |
| // |
| // If the response's Content-Type header is not set, ServeContent |
| // first tries to deduce the type from name's file extension and, |
| // if that fails, falls back to reading the first block of the content |
| // and passing it to DetectContentType. |
| // The name is otherwise unused; in particular it can be empty and is |
| // never sent in the response. |
| // |
| // If modtime is not the zero time or Unix epoch, ServeContent |
| // includes it in a Last-Modified header in the response. If the |
| // request includes an If-Modified-Since header, ServeContent uses |
| // modtime to decide whether the content needs to be sent at all. |
| // |
| // 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. |
| // |
| // Note that *os.File implements the io.ReadSeeker interface. |
| func ServeContent(w ResponseWriter, req *Request, name string, modtime time.Time, content io.ReadSeeker) { |
| sizeFunc := func() (int64, error) { |
| size, err := content.Seek(0, os.SEEK_END) |
| if err != nil { |
| return 0, errSeeker |
| } |
| _, err = content.Seek(0, os.SEEK_SET) |
| if err != nil { |
| return 0, errSeeker |
| } |
| return size, nil |
| } |
| serveContent(w, req, name, modtime, sizeFunc, content) |
| } |
| |
| // errSeeker is returned by ServeContent's sizeFunc when the content |
| // doesn't seek properly. The underlying Seeker's error text isn't |
| // included in the sizeFunc reply so it's not sent over HTTP to end |
| // users. |
| var errSeeker = errors.New("seeker can't seek") |
| |
| // if name is empty, filename is unknown. (used for mime type, before sniffing) |
| // if modtime.IsZero(), modtime is unknown. |
| // 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) |
| if done { |
| return |
| } |
| |
| code := StatusOK |
| |
| // If Content-Type isn't set, use the file's extension to find it, but |
| // if the Content-Type is unset explicitly, do not sniff the type. |
| ctypes, haveType := w.Header()["Content-Type"] |
| var ctype string |
| if !haveType { |
| ctype = mime.TypeByExtension(filepath.Ext(name)) |
| if ctype == "" { |
| // read a chunk to decide between utf-8 text and binary |
| var buf [sniffLen]byte |
| n, _ := io.ReadFull(content, buf[:]) |
| ctype = DetectContentType(buf[:n]) |
| _, err := content.Seek(0, os.SEEK_SET) // rewind to output whole file |
| if err != nil { |
| Error(w, "seeker can't seek", StatusInternalServerError) |
| return |
| } |
| } |
| w.Header().Set("Content-Type", ctype) |
| } else if len(ctypes) > 0 { |
| ctype = ctypes[0] |
| } |
| |
| size, err := sizeFunc() |
| if err != nil { |
| Error(w, err.Error(), StatusInternalServerError) |
| return |
| } |
| |
| // handle Content-Range header. |
| sendSize := size |
| var sendContent io.Reader = content |
| if size >= 0 { |
| ranges, err := parseRange(rangeReq, size) |
| if err != nil { |
| 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 = nil |
| } |
| 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, os.SEEK_SET); 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, os.SEEK_SET); 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") |
| if w.Header().Get("Content-Encoding") == "" { |
| w.Header().Set("Content-Length", strconv.FormatInt(sendSize, 10)) |
| } |
| } |
| |
| w.WriteHeader(code) |
| |
| if r.Method != "HEAD" { |
| io.CopyN(w, sendContent, sendSize) |
| } |
| } |
| |
| 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 |
| } |
| |
| // 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 |
| } |
| w.Header().Set("Last-Modified", modtime.UTC().Format(TimeFormat)) |
| return false |
| } |
| |
| // 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 |
| } |
| } |
| if !timeMatches { |
| rangeReq = "" |
| } |
| } |
| |
| if inm := r.Header.get("If-None-Match"); inm != "" { |
| // Must know ETag. |
| if etag == "" { |
| return rangeReq, false |
| } |
| |
| // 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 |
| } |
| |
| // 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 |
| } |
| } |
| return rangeReq, false |
| } |
| |
| // name is '/'-separated, not filepath.Separator. |
| func serveFile(w ResponseWriter, r *Request, fs FileSystem, name string, redirect bool) { |
| const indexPage = "/index.html" |
| |
| // redirect .../index.html to .../ |
| // can't use Redirect() because that would make the path absolute, |
| // which would be a problem running under StripPrefix |
| if strings.HasSuffix(r.URL.Path, indexPage) { |
| localRedirect(w, r, "./") |
| return |
| } |
| |
| f, err := fs.Open(name) |
| if err != nil { |
| msg, code := toHTTPError(err) |
| Error(w, msg, code) |
| return |
| } |
| defer f.Close() |
| |
| d, err := f.Stat() |
| if err != nil { |
| msg, code := toHTTPError(err) |
| Error(w, msg, code) |
| return |
| } |
| |
| if redirect { |
| // redirect to canonical path: / at end of directory url |
| // r.URL.Path always begins with / |
| url := r.URL.Path |
| if d.IsDir() { |
| if url[len(url)-1] != '/' { |
| localRedirect(w, r, path.Base(url)+"/") |
| return |
| } |
| } else { |
| if url[len(url)-1] == '/' { |
| localRedirect(w, r, "../"+path.Base(url)) |
| return |
| } |
| } |
| } |
| |
| // use contents of index.html for directory, if present |
| if d.IsDir() { |
| 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()) { |
| return |
| } |
| dirList(w, f) |
| return |
| } |
| |
| // serveContent will check modification time |
| sizeFunc := func() (int64, error) { return d.Size(), nil } |
| serveContent(w, r, d.Name(), d.ModTime(), sizeFunc, f) |
| } |
| |
| // toHTTPError returns a non-specific HTTP error message and status code |
| // for a given non-nil error value. It's important that toHTTPError does not |
| // actually return err.Error(), since msg and httpStatus are returned to users, |
| // 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) { |
| return "404 page not found", StatusNotFound |
| } |
| if os.IsPermission(err) { |
| return "403 Forbidden", StatusForbidden |
| } |
| // Default: |
| return "500 Internal Server Error", StatusInternalServerError |
| } |
| |
| // localRedirect gives a Moved Permanently response. |
| // It does not convert relative paths to absolute paths like Redirect does. |
| func localRedirect(w ResponseWriter, r *Request, newPath string) { |
| if q := r.URL.RawQuery; q != "" { |
| newPath += "?" + q |
| } |
| w.Header().Set("Location", newPath) |
| w.WriteHeader(StatusMovedPermanently) |
| } |
| |
| // ServeFile replies to the request with the contents of the named |
| // file or directory. |
| // |
| // As a 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. |
| func ServeFile(w ResponseWriter, r *Request, name string) { |
| dir, file := filepath.Split(name) |
| serveFile(w, r, Dir(dir), file, false) |
| } |
| |
| type fileHandler struct { |
| root FileSystem |
| } |
| |
| // FileServer returns a handler that serves HTTP requests |
| // with the contents of the file system rooted at root. |
| // |
| // To use the operating system's file system implementation, |
| // use http.Dir: |
| // |
| // http.Handle("/", http.FileServer(http.Dir("/tmp"))) |
| // |
| // 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} |
| } |
| |
| func (f *fileHandler) ServeHTTP(w ResponseWriter, r *Request) { |
| upath := r.URL.Path |
| if !strings.HasPrefix(upath, "/") { |
| upath = "/" + upath |
| r.URL.Path = upath |
| } |
| serveFile(w, r, f.root, path.Clean(upath), true) |
| } |
| |
| // httpRange specifies the byte range to be sent to the client. |
| type httpRange struct { |
| start, length int64 |
| } |
| |
| func (r httpRange) contentRange(size int64) string { |
| return fmt.Sprintf("bytes %d-%d/%d", r.start, r.start+r.length-1, size) |
| } |
| |
| func (r httpRange) mimeHeader(contentType string, size int64) textproto.MIMEHeader { |
| return textproto.MIMEHeader{ |
| "Content-Range": {r.contentRange(size)}, |
| "Content-Type": {contentType}, |
| } |
| } |
| |
| // parseRange parses a Range header string as per RFC 2616. |
| func parseRange(s string, size int64) ([]httpRange, error) { |
| if s == "" { |
| return nil, nil // header not present |
| } |
| const b = "bytes=" |
| if !strings.HasPrefix(s, b) { |
| return nil, errors.New("invalid range") |
| } |
| var ranges []httpRange |
| for _, ra := range strings.Split(s[len(b):], ",") { |
| ra = strings.TrimSpace(ra) |
| if ra == "" { |
| continue |
| } |
| i := strings.Index(ra, "-") |
| if i < 0 { |
| return nil, errors.New("invalid range") |
| } |
| start, end := strings.TrimSpace(ra[:i]), strings.TrimSpace(ra[i+1:]) |
| var r httpRange |
| if start == "" { |
| // If no start is specified, end specifies the |
| // range start relative to the end of the file. |
| i, err := strconv.ParseInt(end, 10, 64) |
| if err != nil { |
| return nil, errors.New("invalid range") |
| } |
| if i > size { |
| i = size |
| } |
| r.start = size - i |
| r.length = size - r.start |
| } else { |
| i, err := strconv.ParseInt(start, 10, 64) |
| if err != nil || i >= size || i < 0 { |
| return nil, errors.New("invalid range") |
| } |
| r.start = i |
| if end == "" { |
| // If no end is specified, range extends to end of the file. |
| r.length = size - r.start |
| } else { |
| i, err := strconv.ParseInt(end, 10, 64) |
| if err != nil || r.start > i { |
| return nil, errors.New("invalid range") |
| } |
| if i >= size { |
| i = size - 1 |
| } |
| r.length = i - r.start + 1 |
| } |
| } |
| ranges = append(ranges, r) |
| } |
| return ranges, nil |
| } |
| |
| // countingWriter counts how many bytes have been written to it. |
| type countingWriter int64 |
| |
| func (w *countingWriter) Write(p []byte) (n int, err error) { |
| *w += countingWriter(len(p)) |
| return len(p), nil |
| } |
| |
| // rangesMIMESize returns the number of bytes it takes to encode the |
| // provided ranges as a multipart response. |
| func rangesMIMESize(ranges []httpRange, contentType string, contentSize int64) (encSize int64) { |
| var w countingWriter |
| mw := multipart.NewWriter(&w) |
| for _, ra := range ranges { |
| mw.CreatePart(ra.mimeHeader(contentType, contentSize)) |
| encSize += ra.length |
| } |
| mw.Close() |
| encSize += int64(w) |
| return |
| } |
| |
| func sumRangesSize(ranges []httpRange) (size int64) { |
| for _, ra := range ranges { |
| size += ra.length |
| } |
| 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] } |