mirror of
https://github.com/restic/restic.git
synced 2026-06-06 08:59:44 +00:00
Michael Eischer
339 lines
8.5 KiB
Go
339 lines
8.5 KiB
Go
//go:build debug
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package repository
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import (
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"context"
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"crypto/aes"
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"crypto/cipher"
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"fmt"
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"io"
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"os"
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"runtime"
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"time"
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"github.com/klauspost/compress/zstd"
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"golang.org/x/sync/errgroup"
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"github.com/restic/restic/internal/crypto"
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"github.com/restic/restic/internal/repository/index"
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"github.com/restic/restic/internal/repository/pack"
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"github.com/restic/restic/internal/restic"
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"github.com/restic/restic/internal/ui/progress"
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)
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// DumpIndexes loads each on-disk index file and writes its debug dump to wr.
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func DumpIndexes(ctx context.Context, repo restic.ListerLoaderUnpacked, wr io.Writer, printer progress.Printer) error {
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return index.ForAllIndexes(ctx, repo, repo, func(id restic.ID, idx *index.Index, err error) error {
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printer.S("index_id: %v", id)
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if err != nil {
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return err
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}
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return idx.Dump(wr)
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})
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}
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// ExaminePackOptions configures debug examination of a pack file.
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type ExaminePackOptions struct {
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TryRepair bool
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RepairByte bool
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ExtractPack bool
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ReuploadBlobs bool
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}
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// ExaminePack loads and inspects a pack file and its index entries.
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func ExaminePack(ctx context.Context, repo restic.Repository, id restic.ID, opts ExaminePackOptions, printer progress.Printer) error {
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printer.S("examine %v", id)
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buf, err := repo.LoadRaw(ctx, restic.PackFile, id)
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// also process damaged pack files
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if buf == nil {
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return err
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}
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printer.S(" file size is %v", len(buf))
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gotID := restic.Hash(buf)
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if !id.Equal(gotID) {
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printer.S(" wanted hash %v, got %v", id, gotID)
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} else {
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printer.S(" hash for file content matches")
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}
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printer.S(" ========================================")
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printer.S(" looking for info in the indexes")
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blobsLoaded := false
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// examine all data the indexes have for the pack file
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for b := range repo.ListPacksFromIndex(ctx, restic.NewIDSet(id)) {
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blobs := b.Blobs
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if len(blobs) == 0 {
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continue
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}
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checkPackSize(blobs, len(buf), printer)
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err = loadBlobs(ctx, opts, repo, id, blobs, printer)
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if err != nil {
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printer.E("error: %v", err)
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} else {
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blobsLoaded = true
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}
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}
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printer.S(" ========================================")
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printer.S(" inspect the pack itself")
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blobs, _, err := repo.ListPack(ctx, id, int64(len(buf)))
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if err != nil {
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return fmt.Errorf("pack %v: %v", id.Str(), err)
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}
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checkPackSize(blobs, len(buf), printer)
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if !blobsLoaded {
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return loadBlobs(ctx, opts, repo, id, blobs, printer)
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}
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return nil
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}
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func checkPackSize(blobs restic.Blobs, fileSize int, printer progress.Printer) {
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// track current size and offset
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var size, offset uint64
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blobs.Sort()
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for _, pb := range blobs {
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printer.S(" %v blob %v, offset %-6d, raw length %-6d", pb.Type, pb.ID, pb.Offset, pb.Length)
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if offset != uint64(pb.Offset) {
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printer.S(" hole in file, want offset %v, got %v", offset, pb.Offset)
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}
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offset = uint64(pb.Offset + pb.Length)
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size += uint64(pb.Length)
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}
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size += uint64(pack.CalculateHeaderSize(blobs))
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if uint64(fileSize) != size {
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printer.S(" file sizes do not match: computed %v, file size is %v", size, fileSize)
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} else {
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printer.S(" file sizes match")
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}
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}
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func tryRepairWithBitflip(key *crypto.Key, input []byte, bytewise bool, printer progress.Printer) []byte {
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if bytewise {
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printer.S(" trying to repair blob by finding a broken byte")
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} else {
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printer.S(" trying to repair blob with single bit flip")
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}
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ch := make(chan int)
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var wg errgroup.Group
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done := make(chan struct{})
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var fixed []byte
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var found bool
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workers := runtime.GOMAXPROCS(0)
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printer.S(" spinning up %d worker functions", runtime.GOMAXPROCS(0))
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for i := 0; i < workers; i++ {
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wg.Go(func() error {
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// make a local copy of the buffer
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buf := make([]byte, len(input))
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copy(buf, input)
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testFlip := func(idx int, pattern byte) bool {
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// flip bits
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buf[idx] ^= pattern
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nonce, plaintext := buf[:key.NonceSize()], buf[key.NonceSize():]
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plaintext, err := key.Open(plaintext[:0], nonce, plaintext, nil)
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if err == nil {
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printer.S("")
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printer.S(" blob could be repaired by XORing byte %v with 0x%02x", idx, pattern)
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printer.S(" hash is %v", restic.Hash(plaintext))
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close(done)
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found = true
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fixed = plaintext
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return true
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}
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// flip bits back
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buf[idx] ^= pattern
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return false
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}
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for i := range ch {
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if bytewise {
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for j := 0; j < 255; j++ {
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if testFlip(i, byte(j)) {
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return nil
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}
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}
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} else {
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for j := 0; j < 7; j++ {
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// flip each bit once
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if testFlip(i, (1 << uint(j))) {
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return nil
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}
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}
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}
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}
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return nil
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})
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}
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wg.Go(func() error {
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defer close(ch)
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start := time.Now()
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info := time.Now()
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for i := range input {
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select {
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case ch <- i:
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case <-done:
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printer.S(" done after %v", time.Since(start))
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return nil
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}
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if time.Since(info) > time.Second {
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secs := time.Since(start).Seconds()
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gps := float64(i) / secs
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remaining := len(input) - i
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eta := time.Duration(float64(remaining)/gps) * time.Second
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printer.S("\r%d byte of %d done (%.2f%%), %.0f byte per second, ETA %v",
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i, len(input), float32(i)/float32(len(input))*100, gps, eta)
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info = time.Now()
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}
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}
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return nil
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})
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err := wg.Wait()
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if err != nil {
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panic("all go routines can only return nil")
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}
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if !found {
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printer.S("\n blob could not be repaired")
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}
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return fixed
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}
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func decryptUnsigned(k *crypto.Key, buf []byte) []byte {
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// strip signature at the end
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l := len(buf)
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nonce, ct := buf[:16], buf[16:l-16]
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out := make([]byte, len(ct))
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c, err := aes.NewCipher(k.EncryptionKey[:])
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if err != nil {
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panic(fmt.Sprintf("unable to create cipher: %v", err))
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}
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e := cipher.NewCTR(c, nonce)
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e.XORKeyStream(out, ct)
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return out
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}
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func loadBlobs(ctx context.Context, opts ExaminePackOptions, repo restic.Repository, packID restic.ID, list restic.Blobs, printer progress.Printer) error {
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dec, err := zstd.NewReader(nil)
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if err != nil {
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panic(err)
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}
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packData, err := repo.LoadRaw(ctx, restic.PackFile, packID)
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// allow processing broken pack files
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if packData == nil {
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return err
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}
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err = repo.WithBlobUploader(ctx, func(ctx context.Context, uploader restic.BlobSaverWithAsync) error {
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for _, blob := range list {
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printer.S(" loading blob %v at %v (length %v)", blob.ID, blob.Offset, blob.Length)
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if int(blob.Offset+blob.Length) > len(packData) {
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printer.E("skipping truncated blob")
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continue
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}
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buf := packData[blob.Offset : blob.Offset+blob.Length]
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key := repo.Key()
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nonce, plaintext := buf[:key.NonceSize()], buf[key.NonceSize():]
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plaintext, err = key.Open(plaintext[:0], nonce, plaintext, nil)
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outputPrefix := ""
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filePrefix := ""
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if err != nil {
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printer.E("error decrypting blob: %v", err)
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if opts.TryRepair || opts.RepairByte {
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plaintext = tryRepairWithBitflip(key, buf, opts.RepairByte, printer)
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}
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if plaintext != nil {
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outputPrefix = "repaired "
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filePrefix = "repaired-"
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} else {
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plaintext = decryptUnsigned(key, buf)
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err = storePlainBlob(blob.ID, "damaged-", plaintext, printer)
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if err != nil {
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return err
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}
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continue
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}
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}
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if blob.IsCompressed() {
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decompressed, err := dec.DecodeAll(plaintext, nil)
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if err != nil {
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printer.S(" failed to decompress blob %v", blob.ID)
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}
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if decompressed != nil {
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plaintext = decompressed
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}
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}
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id := restic.Hash(plaintext)
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var prefix string
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if !id.Equal(blob.ID) {
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printer.S(" successfully %vdecrypted blob (length %v), hash is %v, ID does not match, wanted %v", outputPrefix, len(plaintext), id, blob.ID)
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prefix = "wrong-hash-"
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} else {
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printer.S(" successfully %vdecrypted blob (length %v), hash is %v, ID matches", outputPrefix, len(plaintext), id)
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prefix = "correct-"
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}
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if opts.ExtractPack {
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err = storePlainBlob(id, filePrefix+prefix, plaintext, printer)
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if err != nil {
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return err
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}
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}
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if opts.ReuploadBlobs {
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_, _, _, err := uploader.SaveBlob(ctx, blob.Type, plaintext, id, true)
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if err != nil {
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return err
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}
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printer.S(" uploaded %v %v", blob.Type, id)
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}
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}
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return nil
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})
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return err
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}
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func storePlainBlob(id restic.ID, prefix string, plain []byte, printer progress.Printer) error {
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filename := fmt.Sprintf("%s%s.bin", prefix, id)
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f, err := os.Create(filename)
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if err != nil {
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return err
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}
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_, err = f.Write(plain)
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if err != nil {
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_ = f.Close()
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return err
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}
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err = f.Close()
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if err != nil {
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return err
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}
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printer.S("decrypt of blob %v stored at %v", id, filename)
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return nil
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}
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