136 lines
3.8 KiB
Go
136 lines
3.8 KiB
Go
package server
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import (
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"archive/tar"
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"archive/zip"
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"compress/gzip"
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"fmt"
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"github.com/mholt/archiver/v3"
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"github.com/pkg/errors"
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"io"
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"os"
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"path/filepath"
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"reflect"
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"strings"
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"sync"
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"sync/atomic"
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)
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// Look through a given archive and determine if decompressing it would put the server over
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// its allocated disk space limit.
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func (fs *Filesystem) SpaceAvailableForDecompression(dir string, file string) (bool, error) {
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// Don't waste time trying to determine this if we know the server will have the space for
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// it since there is no limit.
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if fs.Server.Build().DiskSpace <= 0 {
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return true, nil
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}
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source, err := fs.SafePath(filepath.Join(dir, file))
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if err != nil {
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return false, err
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}
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wg := new(sync.WaitGroup)
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var dirSize int64
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var cErr error
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// Get the cached size in a parallel process so that if it is not cached we are not
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// waiting an unnecessary amount of time on this call.
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go func() {
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wg.Add(1)
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defer wg.Done()
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dirSize, cErr = fs.getCachedDiskUsage()
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}()
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var size int64
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// In a seperate thread, walk over the archive and figure out just how large the final
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// output would be from dearchiving it.
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go func() {
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wg.Add(1)
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defer wg.Done()
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// Walk all of the files and calculate the total decompressed size of this archive.
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archiver.Walk(source, func(f archiver.File) error {
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atomic.AddInt64(&size, f.Size())
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return nil
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})
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}()
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wg.Wait()
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return ((dirSize + size) / 1000.0 / 1000.0) <= fs.Server.Build().DiskSpace, cErr
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}
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// Decompress a file in a given directory by using the archiver tool to infer the file
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// type and go from there. This will walk over all of the files within the given archive
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// and ensure that there is not a zip-slip attack being attempted by validating that the
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// final path is within the server data directory.
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func (fs *Filesystem) DecompressFile(dir string, file string) error {
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source, err := fs.SafePath(filepath.Join(dir, file))
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if err != nil {
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return errors.WithStack(err)
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}
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// Make sure the file exists basically.
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if _, err := os.Stat(source); err != nil {
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return errors.WithStack(err)
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}
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// Walk over all of the files spinning up an additional go-routine for each file we've encountered
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// and then extract that file from the archive and write it to the disk. If any part of this process
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// encounters an error the entire process will be stopped.
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return archiver.Walk(source, func(f archiver.File) error {
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// Don't waste time with directories, we don't need to create them if they have no contents, and
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// we will ensure the directory exists when opening the file for writing anyways.
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if f.IsDir() {
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return nil
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}
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return fs.extractFileFromArchive(f)
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})
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}
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// Extracts a single file from the archive and writes it to the disk after verifying that it will end
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// up in the server data directory.
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func (fs *Filesystem) extractFileFromArchive(f archiver.File) error {
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var name string
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switch s := f.Sys().(type) {
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case *tar.Header:
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name = s.Name
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case *gzip.Header:
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name = s.Name
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case *zip.FileHeader:
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name = s.Name
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default:
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return errors.New(fmt.Sprintf("could not parse underlying data source with type %s", reflect.TypeOf(s).String()))
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}
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// Guard against a zip-slip attack and prevent writing a file to a destination outside of
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// the server root directory.
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p, err := fs.SafePath(name)
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if err != nil {
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return err
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}
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// Ensure the directory structure for this file exists before trying to write the file
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// to the disk, otherwise we'll have some unexpected fun.
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if err := os.MkdirAll(strings.TrimSuffix(p, filepath.Base(p)), 0755); err != nil {
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return err
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}
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// Open the file and truncate it if it already exists.
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o, err := os.OpenFile(p, os.O_CREATE|os.O_WRONLY|os.O_TRUNC, 0644)
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if err != nil {
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return err
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}
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defer o.Close()
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_, cerr := io.Copy(o, f)
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return cerr
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}
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