first commit

server.go

@@ -0,0 +1,302 @@
+package main
+
+import (
+	"cmp"
+	_ "embed"
+	"fmt"
+	"html/template"
+	"mime"
+	"net/http"
+	"net/url"
+	"os"
+	"path"
+	"path/filepath"
+	"sort"
+	"strings"
+	"time"
+)
+
+//go:embed assets/index.html
+var indexHTML string
+
+//go:embed assets/about.html
+var aboutHTML []byte
+
+//go:embed assets/favicon.ico
+var faviconICO []byte
+
+type server struct {
+	root     string // as configured, used for display paths
+	rootReal string // symlink-resolved root, used for containment checks
+	hidden   bool
+	footer   string
+	tpl      *template.Template
+}
+
+func newServer(cfg *Config) *server {
+	rootReal, err := filepath.EvalSymlinks(cfg.Root)
+	if err != nil {
+		rootReal = cfg.Root
+	}
+	return &server{
+		root:     cfg.Root,
+		rootReal: rootReal,
+		hidden:   cfg.Hidden,
+		footer:   cfg.Footer,
+		tpl:      template.Must(template.New("index").Parse(indexHTML)),
+	}
+}
+
+type row struct {
+	Name    string
+	URL     string
+	IsDir   bool
+	Size    int64
+	ModTime time.Time
+	Type    string
+}
+
+func (r row) SizeS() string { return humanSize(r.Size) }
+func (r row) ModS() string  { return r.ModTime.Format("2006-01-02 15:04") }
+
+type headerCol struct {
+	Label  string
+	URL    string
+	Active bool
+	Desc   bool
+}
+
+type crumb struct{ Name, URL string }
+
+type listData struct {
+	Path      string
+	Crumbs    []crumb
+	Headers   []headerCol
+	Rows      []row
+	HasParent bool
+	Wget      string
+	Footer    string
+}
+
+var sortKeys = map[string]bool{"name": true, "size": true, "modified": true, "type": true}
+
+func (s *server) ServeHTTP(w http.ResponseWriter, r *http.Request) {
+	if r.Method != http.MethodGet && r.Method != http.MethodHead {
+		w.Header().Set("Allow", "GET, HEAD")
+		http.Error(w, "method not allowed", http.StatusMethodNotAllowed)
+		return
+	}
+
+	upath := r.URL.Path
+	if !strings.HasPrefix(upath, "/") {
+		upath = "/" + upath
+	}
+	clean := path.Clean(upath)
+	switch clean {
+	case "/about":
+		w.Header().Set("Content-Type", "text/html; charset=utf-8")
+		w.Write(aboutHTML)
+		return
+	case "/favicon.ico":
+		w.Header().Set("Content-Type", "image/x-icon")
+		w.Header().Set("Cache-Control", "max-age=604800")
+		w.Write(faviconICO)
+		return
+	}
+
+	fsPath := filepath.Join(s.rootReal, filepath.FromSlash(strings.TrimPrefix(clean, "/")))
+	realPath, err := filepath.EvalSymlinks(fsPath)
+	if err != nil {
+		http.NotFound(w, r)
+		return
+	}
+	if realPath != s.rootReal && !strings.HasPrefix(realPath, s.rootReal+string(os.PathSeparator)) {
+		http.NotFound(w, r) // symlink escaping the served root
+		return
+	}
+
+	info, err := os.Stat(realPath)
+	if err != nil {
+		http.NotFound(w, r)
+		return
+	}
+	if info.IsDir() && !strings.HasSuffix(upath, "/") {
+		localRedirect(w, r, path.Base(upath)+"/")
+		return
+	}
+	if !info.IsDir() {
+		s.serveFile(w, r, realPath, filepath.Base(clean), info)
+		return
+	}
+	s.serveListing(w, r, realPath, clean)
+}
+
+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)
+}
+
+func (s *server) serveFile(w http.ResponseWriter, r *http.Request, path, name string, info os.FileInfo) {
+	f, err := os.Open(path)
+	if err != nil {
+		http.Error(w, "cannot open file", http.StatusInternalServerError)
+		return
+	}
+	defer f.Close()
+	w.Header().Set("Content-Disposition",
+		mime.FormatMediaType("attachment", map[string]string{"filename": name}))
+	http.ServeContent(w, r, name, info.ModTime(), f)
+}
+
+func (s *server) serveListing(w http.ResponseWriter, r *http.Request, dirPath, urlPath string) {
+	entries, err := os.ReadDir(dirPath)
+	if err != nil {
+		http.Error(w, "cannot read directory", http.StatusInternalServerError)
+		return
+	}
+
+	sortKey := r.URL.Query().Get("sort")
+	if !sortKeys[sortKey] {
+		sortKey = "name"
+	}
+	desc := r.URL.Query().Get("dir") == "desc"
+
+	dirURL := urlPath
+	if !strings.HasSuffix(dirURL, "/") {
+		dirURL += "/"
+	}
+	rows := make([]row, 0, len(entries))
+	for _, e := range entries {
+		name := e.Name()
+		if !s.hidden && strings.HasPrefix(name, ".") {
+			continue
+		}
+		isDir := e.IsDir()
+		typ := "-"
+		if isDir {
+			typ = "dir"
+		} else if ext := strings.TrimPrefix(filepath.Ext(name), "."); ext != "" {
+			typ = strings.ToLower(ext)
+		}
+		var size int64
+		var mod time.Time
+		if info, err := e.Info(); err == nil {
+			mod = info.ModTime()
+			if !isDir {
+				size = info.Size()
+			}
+		}
+		rows = append(rows, row{
+			Name:    name,
+			URL:     dirURL + url.PathEscape(name),
+			IsDir:   isDir,
+			Size:    size,
+			ModTime: mod,
+			Type:    typ,
+		})
+	}
+
+	sort.SliceStable(rows, func(i, j int) bool {
+		a, b := rows[i], rows[j]
+		if a.IsDir != b.IsDir {
+			return a.IsDir
+		}
+		var c int
+		switch sortKey {
+		case "size":
+			c = cmp.Compare(a.Size, b.Size)
+		case "modified":
+			c = a.ModTime.Compare(b.ModTime)
+		case "type":
+			if c = strings.Compare(a.Type, b.Type); c == 0 {
+				c = strings.Compare(strings.ToLower(a.Name), strings.ToLower(b.Name))
+			}
+		default:
+			c = strings.Compare(strings.ToLower(a.Name), strings.ToLower(b.Name))
+		}
+		if desc {
+			return c > 0
+		}
+		return c < 0
+	})
+
+	headers := []struct {
+		Label string
+		Key   string
+	}{{"Name", "name"}, {"Type", "type"}, {"Size", "size"}, {"Modified", "modified"}}
+	cols := make([]headerCol, len(headers))
+	for i, h := range headers {
+		cols[i] = headerCol{
+			Label:  h.Label,
+			Active: h.Key == sortKey,
+			Desc:   h.Key == sortKey && desc,
+		}
+		d := "asc"
+		if h.Key == sortKey && !desc {
+			d = "desc"
+		}
+		cols[i].URL = dirURL + "?sort=" + h.Key + "&dir=" + d
+	}
+
+	crumbs := []crumb{{Name: "root", URL: "/"}}
+	cur := ""
+	for _, seg := range segments(urlPath) {
+		cur += "/" + seg
+		crumbs = append(crumbs, crumb{Name: seg, URL: cur + "/"})
+	}
+
+	s.tpl.Execute(w, listData{
+		Path:      dirURL,
+		Crumbs:    crumbs,
+		Headers:   cols,
+		Rows:      rows,
+		HasParent: urlPath != "/",
+		Wget:      wgetCmd(r, dirURL),
+		Footer:    s.footer,
+	})
+}
+
+func wgetCmd(r *http.Request, dirURL string) string {
+	cmd := "wget -r -np -nH"
+	if n := len(segments(dirURL)); n > 0 {
+		cmd += fmt.Sprintf(" --cut-dirs=%d", n)
+	}
+	return cmd + ` -R "index.html*" -e robots=off ` + shellQuote(baseURL(r)+dirURL)
+}
+
+// shellQuote quotes s so it is treated as a single literal argument by POSIX shells.
+func shellQuote(s string) string {
+	return "'" + strings.ReplaceAll(s, "'", `'\''`) + "'"
+}
+
+func baseURL(r *http.Request) string {
+	scheme := "http"
+	if r.TLS != nil || r.Header.Get("X-Forwarded-Proto") == "https" {
+		scheme = "https"
+	}
+	return scheme + "://" + r.Host
+}
+
+func segments(p string) []string {
+	p = strings.Trim(p, "/")
+	if p == "" {
+		return nil
+	}
+	return strings.Split(p, "/")
+}
+
+func humanSize(n int64) string {
+	const unit = 1024
+	if n < unit {
+		return fmt.Sprintf("%d B", n)
+	}
+	div, exp := int64(unit), 0
+	for m := n / unit; m >= unit; m /= unit {
+		div *= unit
+		exp++
+	}
+	return fmt.Sprintf("%.1f %ciB", float64(n)/float64(div), "KMGTPE"[exp])
+}