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package echo
import (
"crypto/sha256"
"encoding/base64"
"io"
"io/fs"
"net/http"
"net/url"
"path/filepath"
"github.com/labstack/echo/v4"
)
type routeFunc func(string, echo.HandlerFunc, ...echo.MiddlewareFunc) *echo.Route
func StaticFSSha256Etags(get routeFunc, f fs.FS, prefix, root string, m ...echo.MiddlewareFunc) *echo.Route {
return staticFS(get, f, prefix, root, true, m...)
}
func StaticFS(get routeFunc, f fs.FS, prefix, root string, m ...echo.MiddlewareFunc) *echo.Route {
return staticFS(get, f, prefix, root, false, m...)
}
// TODO: This should support HEAD requests
func staticFS(get routeFunc, f fs.FS, prefix, root string, addEtags bool, m ...echo.MiddlewareFunc) *echo.Route {
if root == "" {
root = "." // For security we want to restrict to CWD.
}
h := func(c echo.Context) error {
p, err := url.PathUnescape(c.Param("*"))
if err != nil {
return err
}
name := filepath.Join(root, filepath.Clean("/"+p)) // "/"+ for security
fp, err := f.Open(name)
if err != nil {
// The access path does not exist
return echo.NotFoundHandler(c)
}
defer fp.Close()
fi, err := fp.Stat()
if err != nil {
// The access path does not exist
return echo.NotFoundHandler(c)
}
// If the request is for a directory and does not end with "/"
p = c.Request().URL.Path // path must not be empty.
if fi.IsDir() && p[len(p)-1] != '/' {
// Redirect to ends with "/"
// return c.Redirect(http.StatusMovedPermanently, p+"/")
// TODO: Serve an index.html if there is one for this dir
return echo.NotFoundHandler(c)
}
fs, ok := fp.(io.ReadSeeker)
if !ok {
c.Logger().Errorf("File %s is not a io.ReadSeeker", p)
return echo.ErrInternalServerError
}
// Only do this if the consumer requests it since it could be expensive
// for high traffic sites as it requires a full read and SHA256
// computation
// TODO: Cache this?
if addEtags {
h := sha256.New()
if _, err := io.Copy(h, fs); err != nil {
c.Logger().Errorf("Error checksumming file %s: %s", p, err)
return echo.ErrInternalServerError
}
etag := base64.RawStdEncoding.EncodeToString(h.Sum(nil))
c.Response().Header().Add("ETag", etag)
if _, err := fs.Seek(0, io.SeekStart); err != nil {
c.Logger().Errorf("Error seeking 0 in file %s: %s", p, err)
return echo.ErrInternalServerError
}
}
http.ServeContent(c.Response(), c.Request(), fi.Name(), fi.ModTime(), fs)
return nil
}
// Handle added routes based on trailing slash:
// /prefix => exact route "/prefix" + any route "/prefix/*"
// /prefix/ => only any route "/prefix/*"
if prefix != "" {
if prefix[len(prefix)-1] == '/' {
// Only add any route for intentional trailing slash
return get(prefix+"*", h, m...)
}
get(prefix, h, m...)
}
return get(prefix+"/*", h, m...)
}
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