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-rw-r--r--src/net/http/fs.go556
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diff --git a/src/net/http/fs.go b/src/net/http/fs.go
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+// 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"
+ "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
+ Readdir(count int) ([]os.FileInfo, error)
+ Seek(offset int64, whence int) (int64, error)
+ Stat() (os.FileInfo, error)
+}
+
+func dirList(w ResponseWriter, f File) {
+ w.Header().Set("Content-Type", "text/html; charset=utf-8")
+ fmt.Fprintf(w, "<pre>\n")
+ for {
+ dirs, err := f.Readdir(100)
+ if err != nil || len(dirs) == 0 {
+ break
+ }
+ 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, 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)
+ }
+}
+
+// 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() {
+ 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 {
+ // TODO expose actual error?
+ NotFound(w, r)
+ return
+ }
+ defer f.Close()
+
+ d, err1 := f.Stat()
+ if err1 != nil {
+ // TODO expose actual error?
+ NotFound(w, r)
+ 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)
+}
+
+// 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.
+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")))
+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
+}
generated by cgit v1.2.3 (git 2.39.1) at 2024-06-13 14:06:08 +0000