diff --git a/handler.go b/handler.go
new file mode 100644
index 00000000..ed553cd3
--- /dev/null
+++ b/handler.go
@@ -0,0 +1,731 @@
+package httprouter
+
+import (
+ "errors"
+ "fmt"
+ "io"
+ "io/fs"
+ "mime"
+ "mime/multipart"
+ "net/http"
+ "net/textproto"
+ "net/url"
+ "path"
+ "path/filepath"
+ "sort"
+ "strconv"
+ "strings"
+ "time"
+)
+
+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() }
+
+var htmlReplacer = strings.NewReplacer(
+ "&", "&",
+ "<", "<",
+ ">", ">",
+ // """ is shorter than """.
+ `"`, """,
+ // "'" is shorter than "'" and apos was not in HTML until HTML5.
+ "'", "'",
+)
+
+func dirList(w http.ResponseWriter, r *http.Request, f http.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 {
+ http.Error(w, "Error reading directory", http.StatusInternalServerError)
+ return
+ }
+ 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, "\n")
+ 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, "%s\n", url.String(), htmlReplacer.Replace(name))
+ }
+ fmt.Fprintf(w, "\n")
+}
+
+type customHandler struct {
+ root http.FileSystem
+}
+
+func FileServer(root http.FileSystem) http.Handler {
+ return &customHandler{root}
+}
+
+// different from http.Handler, customHandler set redirect to false for escaping
+// unintended condition
+func (f *customHandler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+ upath := r.URL.Path
+ if !strings.HasPrefix(upath, "/") {
+ upath = "/" + upath
+ r.URL.Path = upath
+ }
+ serveFile(w, r, f.root, path.Clean(upath), false)
+}
+
+func serveFile(w http.ResponseWriter, r *http.Request, fs http.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)
+ http.Error(w, msg, code)
+ return
+ }
+ defer f.Close()
+
+ d, err := f.Stat()
+ if err != nil {
+ msg, code := toHTTPError(err)
+ http.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
+ }
+ }
+ }
+
+ if d.IsDir() {
+ url := r.URL.Path
+ // 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
+ index := strings.TrimSuffix(name, "/") + indexPage
+ ff, err := fs.Open(index)
+ if err == nil {
+ defer ff.Close()
+ dd, err := ff.Stat()
+ if err == nil {
+ d = dd
+ f = ff
+ }
+ }
+ }
+
+ // Still a directory? (we didn't find an index.html file)
+ if d.IsDir() {
+ if checkIfModifiedSince(r, d.ModTime()) == condFalse {
+ writeNotModified(w)
+ return
+ }
+ setLastModified(w, d.ModTime())
+ dirList(w, r, f)
+ return
+ }
+
+ // serveContent will check modification time
+ sizeFunc := func() (int64, error) { return d.Size(), nil }
+ serveContent(w, r, d.Name(), d.ModTime(), sizeFunc, f)
+}
+
+func writeNotModified(w http.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(http.StatusNotModified)
+}
+
+type condResult int
+
+const (
+ condNone condResult = iota
+ condTrue
+ condFalse
+)
+
+func checkPreconditions(w http.ResponseWriter, r *http.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(http.StatusPreconditionFailed)
+ return true, ""
+ }
+ switch checkIfNoneMatch(w, r) {
+ case condFalse:
+ if r.Method == "GET" || r.Method == "HEAD" {
+ writeNotModified(w)
+ return true, ""
+ } else {
+ w.WriteHeader(http.StatusPreconditionFailed)
+ return true, ""
+ }
+ case condNone:
+ if checkIfModifiedSince(r, modtime) == condFalse {
+ writeNotModified(w)
+ return true, ""
+ }
+ }
+
+ rangeHeader = r.Header.Get("Range")
+ if rangeHeader != "" && checkIfRange(w, r, modtime) == condFalse {
+ rangeHeader = ""
+ }
+ return false, rangeHeader
+}
+
+func checkIfModifiedSince(r *http.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 := http.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
+}
+
+func checkIfMatch(w http.ResponseWriter, r *http.Request) condResult {
+ im := r.Header.Get("If-Match")
+ if im == "" {
+ return condNone
+ }
+ for {
+ im = textproto.TrimString(im)
+ if len(im) == 0 {
+ break
+ }
+ 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
+ }
+
+ return condFalse
+}
+
+func checkIfRange(w http.ResponseWriter, r *http.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 := http.ParseTime(ir)
+ if err != nil {
+ return condFalse
+ }
+ if t.Unix() == modtime.Unix() {
+ return condTrue
+ }
+ return condFalse
+}
+
+func checkIfUnmodifiedSince(r *http.Request, modtime time.Time) condResult {
+ ius := r.Header.Get("If-Unmodified-Since")
+ if ius == "" || isZeroTime(modtime) {
+ return condNone
+ }
+ t, err := http.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 http.ResponseWriter, r *http.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 == "" {
+ break
+ }
+ if etagWeakMatch(etag, w.Header().Get("Etag")) {
+ return condFalse
+ }
+ buf = remain
+ }
+ return condTrue
+}
+
+func scanETag(s string) (etag string, remain string) {
+ s = textproto.TrimString(s)
+ start := 0
+ if strings.HasPrefix(s, "W/") {
+ start = 2
+ }
+ if len(s[start:]) < 2 || s[start] != '"' {
+ return "", ""
+ }
+ // 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 "", ""
+}
+
+// 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/")
+}
+
+var errNoOverlap = errors.New("invalid range: failed to overlap")
+
+const sniffLen = 512
+
+func serveContent(w http.ResponseWriter, r *http.Request, name string, modtime time.Time, sizeFunc func() (int64, error), content io.ReadSeeker) {
+ setLastModified(w, modtime)
+ done, rangeReq := checkPreconditions(w, r, modtime)
+ if done {
+ return
+ }
+
+ code := http.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 = http.DetectContentType(buf[:n])
+ _, err := content.Seek(0, io.SeekStart) // rewind to output whole file
+ if err != nil {
+ http.Error(w, "seeker can't seek", http.StatusInternalServerError)
+ return
+ }
+ }
+ w.Header().Set("Content-Type", ctype)
+ } else if len(ctypes) > 0 {
+ ctype = ctypes[0]
+ }
+
+ size, err := sizeFunc()
+ if err != nil {
+ http.Error(w, err.Error(), http.StatusInternalServerError)
+ return
+ }
+ if size < 0 {
+ // Should never happen but just to be sure
+ http.Error(w, "negative content size computed", http.StatusInternalServerError)
+ return
+ }
+
+ // handle Content-Range header.
+ sendSize := size
+ var sendContent io.Reader = content
+ 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
+ }
+ w.Header().Set("Content-Range", fmt.Sprintf("bytes */%d", size))
+ fallthrough
+ default:
+ http.Error(w, err.Error(), http.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 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 {
+ http.Error(w, err.Error(), http.StatusRequestedRangeNotSatisfiable)
+ return
+ }
+ sendSize = ra.length
+ code = http.StatusPartialContent
+ w.Header().Set("Content-Range", ra.contentRange(size))
+ case len(ranges) > 1:
+ sendSize = rangesMIMESize(ranges, ctype, size)
+ code = http.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")
+
+ // We should be able to unconditionally set the Content-Length here.
+ //
+ // However, there is a pattern observed in the wild that this breaks:
+ // The user wraps the ResponseWriter in one which gzips data written to it,
+ // and sets "Content-Encoding: gzip".
+ //
+ // The user shouldn't be doing this; the serveContent path here depends
+ // on serving seekable data with a known length. If you want to compress
+ // on the fly, then you shouldn't be using ServeFile/ServeContent, or
+ // you should compress the entire file up-front and provide a seekable
+ // view of the compressed data.
+ //
+ // However, since we've observed this pattern in the wild, and since
+ // setting Content-Length here breaks code that mostly-works today,
+ // skip setting Content-Length if the user set Content-Encoding.
+ //
+ // If this is a range request, always set Content-Length.
+ // If the user isn't changing the bytes sent in the ResponseWrite,
+ // the Content-Length will be correct.
+ // If the user is changing the bytes sent, then the range request wasn't
+ // going to work properly anyway and we aren't worse off.
+ //
+ // A possible future improvement on this might be to look at the type
+ // of the ResponseWriter, and always set Content-Length if it's one
+ // that we recognize.
+ if len(ranges) > 0 || 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)
+
+func setLastModified(w http.ResponseWriter, modtime time.Time) {
+ if !isZeroTime(modtime) {
+ w.Header().Set("Last-Modified", modtime.UTC().Format(http.TimeFormat))
+ }
+}
+
+func isZeroTime(t time.Time) bool {
+ return t.IsZero() || t.Equal(unixEpochTime)
+}
+
+// localRedirect gives a Moved Permanently response.
+// It does not convert relative paths to absolute paths like Redirect does.
+func localRedirect(w http.ResponseWriter, r *http.Request, newPath string) {
+ if q := r.URL.RawQuery; q != "" {
+ newPath += "?" + q
+ }
+ w.Header().Set("Location", newPath)
+ w.WriteHeader(http.StatusMovedPermanently)
+}
+
+// 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},
+ }
+}
+
+// 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
+}
+
+// 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 == "" {
+ return nil, nil // header not present
+ }
+ const b = "bytes="
+ if !strings.HasPrefix(s, b) {
+ return nil, errors.New("invalid range")
+ }
+ var ranges []httpRange
+ noOverlap := false
+ for _, ra := range strings.Split(s[len(b):], ",") {
+ ra = textproto.TrimString(ra)
+ if ra == "" {
+ continue
+ }
+ start, end, ok := strings.Cut(ra, "-")
+ if !ok {
+ return nil, errors.New("invalid range")
+ }
+ 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,
+ // and we are dealing with
+ // 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 i < 0 || 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 < 0 {
+ return nil, errors.New("invalid range")
+ }
+ if i >= size {
+ // If the range begins after the size of the content,
+ // then it does not overlap.
+ noOverlap = true
+ continue
+ }
+ 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)
+ }
+ if noOverlap && len(ranges) == 0 {
+ // The specified ranges did not overlap with the content.
+ return nil, errNoOverlap
+ }
+ return ranges, 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
+}
+
+// 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 errors.Is(err, fs.ErrNotExist) {
+ return "404 page not found", http.StatusNotFound
+ }
+ if errors.Is(err, fs.ErrPermission) {
+ return "403 Forbidden", http.StatusForbidden
+ }
+ // Default:
+ return "500 Internal Server Error", http.StatusInternalServerError
+}
\ No newline at end of file
diff --git a/router.go b/router.go
index 818448a4..49b1bd17 100644
--- a/router.go
+++ b/router.go
@@ -372,7 +372,7 @@ func (r *Router) ServeFiles(path string, root http.FileSystem) {
panic("path must end with /*filepath in path '" + path + "'")
}
- fileServer := http.FileServer(root)
+ fileServer := FileServer(root)
r.GET(path, func(w http.ResponseWriter, req *http.Request, ps Params) {
req.URL.Path = ps.ByName("filepath")