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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.
// Based on https://golang.org/src/net/http/fs.go
package httpfs
import (
"errors"
"net/http"
"os"
"path"
"path/filepath"
"strings"
"gitlab.com/gitlab-org/labkit/log"
)
var (
errInvalidChar = errors.New("http: invalid character in file path")
)
// fileSystemPaths implements the http.FileSystem interface
type fileSystemPaths struct {
allowedPaths []string
}
// NewFileSystemPath creates a new fileSystemPaths that can be used to register
// a file:// protocol with an http.Transport.
func NewFileSystemPath(allowedPaths []string) (http.FileSystem, error) {
for k, allowedPath := range allowedPaths {
strippedPath := ensureEndingSlash(allowedPath)
var err error
allowedPaths[k], err = filepath.Abs(strippedPath)
if err != nil {
return nil, err
}
}
return &fileSystemPaths{
allowedPaths: allowedPaths,
}, nil
}
// Open a file by name if it exists inside the allowedPaths
func (p *fileSystemPaths) Open(name string) (http.File, error) {
// taken from http.Dir#open https://golang.org/src/net/http/fs.go?s=2108:2152#L70
if filepath.Separator != '/' && strings.ContainsRune(name, filepath.Separator) {
return nil, errInvalidChar
}
cleanedPath := filepath.FromSlash(path.Clean("/" + name))
absPath, err := filepath.Abs(cleanedPath)
if err != nil {
return nil, err
}
for _, allowedPath := range p.allowedPaths {
// allowedPath may be a single / in chroot so we need to ensure it's not double slash
if strings.HasPrefix(absPath, ensureEndingSlash(allowedPath)) {
return os.Open(absPath)
}
}
log.WithError(os.ErrPermission).Errorf("requested filepath %q not in allowed paths: %q",
absPath, strings.Join(p.allowedPaths, string(os.PathListSeparator)))
// os.ErrPermission is converted to http.StatusForbidden
// https://github.com/golang/go/blob/release-branch.go1.15/src/net/http/fs.go#L635
return nil, os.ErrPermission
}
func ensureEndingSlash(path string) string {
if strings.HasSuffix(path, "/") {
return path
}
return path + "/"
}
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