mirror of
https://github.com/caddyserver/caddy.git
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301 lines
8.8 KiB
Go
301 lines
8.8 KiB
Go
// Package staticfiles provides middleware for serving static files from disk.
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// Its handler is the default HTTP handler for the HTTP server.
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//
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// TODO: Should this package be rolled into the httpserver package?
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package staticfiles
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import (
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"math/rand"
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"net/http"
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"os"
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"path"
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"path/filepath"
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"runtime"
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"strconv"
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"strings"
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"github.com/mholt/caddy"
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)
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// FileServer implements a production-ready file server
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// and is the 'default' handler for all requests to Caddy.
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// It simply loads and serves the URI requested. FileServer
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// is adapted from the one in net/http by the Go authors.
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// Significant modifications have been made.
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//
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// Original license:
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//
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// Copyright 2009 The Go Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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type FileServer struct {
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Root http.FileSystem // jailed access to the file system
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Hide []string // list of files for which to respond with "Not Found"
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}
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// ServeHTTP serves static files for r according to fs's configuration.
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func (fs FileServer) ServeHTTP(w http.ResponseWriter, r *http.Request) (int, error) {
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return fs.serveFile(w, r)
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}
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// serveFile writes the specified file to the HTTP response.
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// name is '/'-separated, not filepath.Separator.
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func (fs FileServer) serveFile(w http.ResponseWriter, r *http.Request) (int, error) {
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reqPath := r.URL.Path
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// Prevent absolute path access on Windows.
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// TODO remove when stdlib http.Dir fixes this.
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if runtime.GOOS == "windows" && len(reqPath) > 0 && filepath.IsAbs(reqPath[1:]) {
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return http.StatusNotFound, nil
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}
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// open the requested file
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f, err := fs.Root.Open(reqPath)
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if err != nil {
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// TODO: remove when http.Dir handles this (Go 1.9?)
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// Go issue #18984
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err = mapFSRootOpenErr(err)
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if os.IsNotExist(err) {
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return http.StatusNotFound, nil
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} else if os.IsPermission(err) {
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return http.StatusForbidden, err
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}
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// otherwise, maybe the server is under load and ran out of file descriptors?
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backoff := int(3 + rand.Int31()%3) // 3–5 seconds to prevent a stampede
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w.Header().Set("Retry-After", strconv.Itoa(backoff))
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return http.StatusServiceUnavailable, err
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}
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defer f.Close()
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// get information about the file
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d, err := f.Stat()
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if err != nil {
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if os.IsNotExist(err) {
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return http.StatusNotFound, nil
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} else if os.IsPermission(err) {
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return http.StatusForbidden, err
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}
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// return a different status code than above to distinguish these cases
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return http.StatusInternalServerError, err
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}
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// redirect to canonical path (being careful to preserve other parts of URL and
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// considering cases where a site is defined with a path prefix that gets stripped)
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urlCopy := *r.URL
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pathPrefix, _ := r.Context().Value(caddy.CtxKey("path_prefix")).(string)
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if pathPrefix != "/" {
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urlCopy.Path = pathPrefix + urlCopy.Path
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}
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if urlCopy.Path == "" {
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urlCopy.Path = "/"
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}
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if d.IsDir() {
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// ensure there is a trailing slash
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if urlCopy.Path[len(urlCopy.Path)-1] != '/' {
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urlCopy.Path += "/"
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http.Redirect(w, r, urlCopy.String(), http.StatusMovedPermanently)
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return http.StatusMovedPermanently, nil
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}
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} else {
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// ensure no trailing slash
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redir := false
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if urlCopy.Path[len(urlCopy.Path)-1] == '/' {
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urlCopy.Path = urlCopy.Path[:len(urlCopy.Path)-1]
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redir = true
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}
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// if an index file was explicitly requested, strip file name from the request
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// ("/foo/index.html" -> "/foo/")
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var requestPage = path.Base(urlCopy.Path)
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for _, indexPage := range IndexPages {
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if requestPage == indexPage {
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urlCopy.Path = urlCopy.Path[:len(urlCopy.Path)-len(indexPage)]
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redir = true
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break
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}
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}
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if redir {
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http.Redirect(w, r, urlCopy.String(), http.StatusMovedPermanently)
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return http.StatusMovedPermanently, nil
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}
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}
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// use contents of an index file, if present, for directory requests
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if d.IsDir() {
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for _, indexPage := range IndexPages {
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indexPath := path.Join(reqPath, indexPage)
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indexFile, err := fs.Root.Open(indexPath)
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if err != nil {
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continue
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}
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indexInfo, err := indexFile.Stat()
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if err != nil {
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indexFile.Close()
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continue
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}
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// this defer does not leak fds even though we are in a loop,
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// because previous iterations of the loop must have had an
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// err, so there's nothing to close from earlier iterations.
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defer indexFile.Close()
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// close previously-opened file immediately to release fd
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f.Close()
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// switch to using the index file, and we're done here
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d = indexInfo
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f = indexFile
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reqPath = indexPath
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break
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}
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}
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// return Not Found if we either did not find an index file (and thus are
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// still a directory) or if this file is supposed to be hidden
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if d.IsDir() || fs.IsHidden(d) {
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return http.StatusNotFound, nil
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}
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etag := calculateEtag(d)
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// look for compressed versions of the file on disk, if the client supports that encoding
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for _, encoding := range staticEncodingPriority {
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// see if the client accepts a compressed encoding we offer
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acceptEncoding := strings.Split(r.Header.Get("Accept-Encoding"), ",")
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accepted := false
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for _, acc := range acceptEncoding {
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if strings.TrimSpace(acc) == encoding {
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accepted = true
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break
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}
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}
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// if client doesn't support this encoding, don't even bother; try next one
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if !accepted {
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continue
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}
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// see if the compressed version of this file exists
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encodedFile, err := fs.Root.Open(reqPath + staticEncoding[encoding])
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if err != nil {
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continue
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}
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encodedFileInfo, err := encodedFile.Stat()
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if err != nil {
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encodedFile.Close()
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continue
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}
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// close the encoded file when we're done, and close the
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// previously-opened file immediately to release the fd
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defer encodedFile.Close()
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f.Close()
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// the encoded file is now what we're serving
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f = encodedFile
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etag = calculateEtag(encodedFileInfo)
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w.Header().Add("Vary", "Accept-Encoding")
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w.Header().Set("Content-Encoding", encoding)
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w.Header().Set("Content-Length", strconv.FormatInt(encodedFileInfo.Size(), 10))
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break
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}
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// Set the ETag returned to the user-agent. Note that a conditional If-None-Match
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// request is handled in http.ServeContent below, which checks against this ETag value.
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w.Header().Set("ETag", etag)
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// Note: Errors generated by ServeContent are written immediately
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// to the response. This usually only happens if seeking fails (rare).
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// Its signature does not bubble the error up to us, so we cannot
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// return it for any logging middleware to record. Oh well.
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http.ServeContent(w, r, d.Name(), d.ModTime(), f)
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return http.StatusOK, nil
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}
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// IsHidden checks if file with FileInfo d is on hide list.
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func (fs FileServer) IsHidden(d os.FileInfo) bool {
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for _, hiddenPath := range fs.Hide {
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// TODO: Could these FileInfos be stored instead of their paths, to avoid opening them all the time?
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if hFile, err := fs.Root.Open(hiddenPath); err == nil {
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fs, _ := hFile.Stat()
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hFile.Close()
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if os.SameFile(d, fs) {
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return true
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}
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}
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}
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return false
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}
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// calculateEtag produces a strong etag by default, although, for
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// efficiency reasons, it does not actually consume the contents
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// of the file to make a hash of all the bytes. ¯\_(ツ)_/¯
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// Prefix the etag with "W/" to convert it into a weak etag.
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// See: https://tools.ietf.org/html/rfc7232#section-2.3
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func calculateEtag(d os.FileInfo) string {
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t := strconv.FormatInt(d.ModTime().Unix(), 36)
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s := strconv.FormatInt(d.Size(), 36)
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return `"` + t + s + `"`
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}
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// IndexPages is a list of pages that may be understood as
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// the "index" files to directories.
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var IndexPages = []string{
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"index.html",
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"index.htm",
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"index.txt",
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"default.html",
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"default.htm",
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"default.txt",
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}
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// staticEncoding is a map of content-encoding to a file extension.
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// If client accepts given encoding (via Accept-Encoding header) and compressed file with given extensions exists
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// it will be served to the client instead of original one.
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var staticEncoding = map[string]string{
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"gzip": ".gz",
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"br": ".br",
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}
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// staticEncodingPriority is a list of preferred static encodings (most efficient compression to least one).
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var staticEncodingPriority = []string{
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"br",
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"gzip",
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}
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// mapFSRootOpenErr maps the provided non-nil error
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// to a possibly better non-nil error. In particular, it turns OS-specific errors
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// about opening files in non-directories into os.ErrNotExist.
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//
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// TODO: remove when http.Dir handles this (slated for Go 1.9)
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// Go issue #18984
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func mapFSRootOpenErr(originalErr error) error {
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if os.IsNotExist(originalErr) || os.IsPermission(originalErr) {
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return originalErr
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}
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perr, ok := originalErr.(*os.PathError)
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if !ok {
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return originalErr
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}
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name := perr.Path
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parts := strings.Split(name, string(filepath.Separator))
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for i := range parts {
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if parts[i] == "" {
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continue
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}
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fi, err := os.Stat(strings.Join(parts[:i+1], string(filepath.Separator)))
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if err != nil {
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return originalErr
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}
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if !fi.IsDir() {
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return os.ErrNotExist
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}
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}
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return originalErr
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}
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