restic/cmd/restic/cmd_debug.go
2022-10-21 21:26:45 +02:00

565 lines
13 KiB
Go

//go:build debug
// +build debug
package main
import (
"context"
"crypto/aes"
"crypto/cipher"
"encoding/json"
"fmt"
"io"
"os"
"runtime"
"sort"
"sync"
"time"
"github.com/klauspost/compress/zstd"
"github.com/spf13/cobra"
"golang.org/x/sync/errgroup"
"github.com/restic/restic/internal/backend"
"github.com/restic/restic/internal/crypto"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/index"
"github.com/restic/restic/internal/pack"
"github.com/restic/restic/internal/repository"
"github.com/restic/restic/internal/restic"
)
var cmdDebug = &cobra.Command{
Use: "debug",
Short: "Debug commands",
}
var cmdDebugDump = &cobra.Command{
Use: "dump [indexes|snapshots|all|packs]",
Short: "Dump data structures",
Long: `
The "dump" command dumps data structures from the repository as JSON objects. It
is used for debugging purposes only.
EXIT STATUS
===========
Exit status is 0 if the command was successful, and non-zero if there was any error.
`,
DisableAutoGenTag: true,
RunE: func(cmd *cobra.Command, args []string) error {
return runDebugDump(cmd.Context(), globalOptions, args)
},
}
var tryRepair bool
var repairByte bool
var extractPack bool
var reuploadBlobs bool
func init() {
cmdRoot.AddCommand(cmdDebug)
cmdDebug.AddCommand(cmdDebugDump)
cmdDebug.AddCommand(cmdDebugExamine)
cmdDebugExamine.Flags().BoolVar(&extractPack, "extract-pack", false, "write blobs to the current directory")
cmdDebugExamine.Flags().BoolVar(&reuploadBlobs, "reupload-blobs", false, "reupload blobs to the repository")
cmdDebugExamine.Flags().BoolVar(&tryRepair, "try-repair", false, "try to repair broken blobs with single bit flips")
cmdDebugExamine.Flags().BoolVar(&repairByte, "repair-byte", false, "try to repair broken blobs by trying bytes")
}
func prettyPrintJSON(wr io.Writer, item interface{}) error {
buf, err := json.MarshalIndent(item, "", " ")
if err != nil {
return err
}
_, err = wr.Write(append(buf, '\n'))
return err
}
func debugPrintSnapshots(ctx context.Context, repo *repository.Repository, wr io.Writer) error {
return restic.ForAllSnapshots(ctx, repo.Backend(), repo, nil, func(id restic.ID, snapshot *restic.Snapshot, err error) error {
if err != nil {
return err
}
fmt.Fprintf(wr, "snapshot_id: %v\n", id)
return prettyPrintJSON(wr, snapshot)
})
}
// Pack is the struct used in printPacks.
type Pack struct {
Name string `json:"name"`
Blobs []Blob `json:"blobs"`
}
// Blob is the struct used in printPacks.
type Blob struct {
Type restic.BlobType `json:"type"`
Length uint `json:"length"`
ID restic.ID `json:"id"`
Offset uint `json:"offset"`
}
func printPacks(ctx context.Context, repo *repository.Repository, wr io.Writer) error {
var m sync.Mutex
return restic.ParallelList(ctx, repo.Backend(), restic.PackFile, repo.Connections(), func(ctx context.Context, id restic.ID, size int64) error {
blobs, _, err := repo.ListPack(ctx, id, size)
if err != nil {
Warnf("error for pack %v: %v\n", id.Str(), err)
return nil
}
p := Pack{
Name: id.String(),
Blobs: make([]Blob, len(blobs)),
}
for i, blob := range blobs {
p.Blobs[i] = Blob{
Type: blob.Type,
Length: blob.Length,
ID: blob.ID,
Offset: blob.Offset,
}
}
m.Lock()
defer m.Unlock()
return prettyPrintJSON(wr, p)
})
}
func dumpIndexes(ctx context.Context, repo restic.Repository, wr io.Writer) error {
return index.ForAllIndexes(ctx, repo, func(id restic.ID, idx *index.Index, oldFormat bool, err error) error {
Printf("index_id: %v\n", id)
if err != nil {
return err
}
return idx.Dump(wr)
})
}
func runDebugDump(ctx context.Context, gopts GlobalOptions, args []string) error {
if len(args) != 1 {
return errors.Fatal("type not specified")
}
repo, err := OpenRepository(ctx, gopts)
if err != nil {
return err
}
if !gopts.NoLock {
var lock *restic.Lock
lock, ctx, err = lockRepo(ctx, repo)
defer unlockRepo(lock)
if err != nil {
return err
}
}
tpe := args[0]
switch tpe {
case "indexes":
return dumpIndexes(ctx, repo, gopts.stdout)
case "snapshots":
return debugPrintSnapshots(ctx, repo, gopts.stdout)
case "packs":
return printPacks(ctx, repo, gopts.stdout)
case "all":
Printf("snapshots:\n")
err := debugPrintSnapshots(ctx, repo, gopts.stdout)
if err != nil {
return err
}
Printf("\nindexes:\n")
err = dumpIndexes(ctx, repo, gopts.stdout)
if err != nil {
return err
}
return nil
default:
return errors.Fatalf("no such type %q", tpe)
}
}
var cmdDebugExamine = &cobra.Command{
Use: "examine pack-ID...",
Short: "Examine a pack file",
DisableAutoGenTag: true,
RunE: func(cmd *cobra.Command, args []string) error {
return runDebugExamine(cmd.Context(), globalOptions, args)
},
}
func tryRepairWithBitflip(ctx context.Context, key *crypto.Key, input []byte, bytewise bool) []byte {
if bytewise {
Printf(" trying to repair blob by finding a broken byte\n")
} else {
Printf(" trying to repair blob with single bit flip\n")
}
ch := make(chan int)
var wg errgroup.Group
done := make(chan struct{})
var fixed []byte
var found bool
workers := runtime.GOMAXPROCS(0)
Printf(" spinning up %d worker functions\n", runtime.GOMAXPROCS(0))
for i := 0; i < workers; i++ {
wg.Go(func() error {
// make a local copy of the buffer
buf := make([]byte, len(input))
copy(buf, input)
testFlip := func(idx int, pattern byte) bool {
// flip bits
buf[idx] ^= pattern
nonce, plaintext := buf[:key.NonceSize()], buf[key.NonceSize():]
plaintext, err := key.Open(plaintext[:0], nonce, plaintext, nil)
if err == nil {
Printf("\n")
Printf(" blob could be repaired by XORing byte %v with 0x%02x\n", idx, pattern)
Printf(" hash is %v\n", restic.Hash(plaintext))
close(done)
found = true
fixed = plaintext
return true
}
// flip bits back
buf[idx] ^= pattern
return false
}
for i := range ch {
if bytewise {
for j := 0; j < 255; j++ {
if testFlip(i, byte(j)) {
return nil
}
}
} else {
for j := 0; j < 7; j++ {
// flip each bit once
if testFlip(i, (1 << uint(j))) {
return nil
}
}
}
}
return nil
})
}
wg.Go(func() error {
defer close(ch)
start := time.Now()
info := time.Now()
for i := range input {
select {
case ch <- i:
case <-done:
Printf(" done after %v\n", time.Since(start))
return nil
}
if time.Since(info) > time.Second {
secs := time.Since(start).Seconds()
gps := float64(i) / secs
remaining := len(input) - i
eta := time.Duration(float64(remaining)/gps) * time.Second
Printf("\r%d byte of %d done (%.2f%%), %.0f byte per second, ETA %v",
i, len(input), float32(i)/float32(len(input))*100, gps, eta)
info = time.Now()
}
}
return nil
})
err := wg.Wait()
if err != nil {
panic("all go rountines can only return nil")
}
if !found {
Printf("\n blob could not be repaired\n")
}
return fixed
}
func decryptUnsigned(ctx context.Context, k *crypto.Key, buf []byte) []byte {
// strip signature at the end
l := len(buf)
nonce, ct := buf[:16], buf[16:l-16]
out := make([]byte, len(ct))
c, err := aes.NewCipher(k.EncryptionKey[:])
if err != nil {
panic(fmt.Sprintf("unable to create cipher: %v", err))
}
e := cipher.NewCTR(c, nonce)
e.XORKeyStream(out, ct)
return out
}
func loadBlobs(ctx context.Context, repo restic.Repository, packID restic.ID, list []restic.Blob) error {
dec, err := zstd.NewReader(nil)
if err != nil {
panic(err)
}
be := repo.Backend()
h := restic.Handle{
Name: packID.String(),
Type: restic.PackFile,
}
for _, blob := range list {
Printf(" loading blob %v at %v (length %v)\n", blob.ID, blob.Offset, blob.Length)
buf := make([]byte, blob.Length)
err := be.Load(ctx, h, int(blob.Length), int64(blob.Offset), func(rd io.Reader) error {
n, err := io.ReadFull(rd, buf)
if err != nil {
return fmt.Errorf("read error after %d bytes: %v", n, err)
}
return nil
})
if err != nil {
Warnf("error read: %v\n", err)
continue
}
key := repo.Key()
nonce, plaintext := buf[:key.NonceSize()], buf[key.NonceSize():]
plaintext, err = key.Open(plaintext[:0], nonce, plaintext, nil)
outputPrefix := ""
filePrefix := ""
if err != nil {
Warnf("error decrypting blob: %v\n", err)
if tryRepair || repairByte {
plaintext = tryRepairWithBitflip(ctx, key, buf, repairByte)
}
if plaintext != nil {
outputPrefix = "repaired "
filePrefix = "repaired-"
} else {
plaintext = decryptUnsigned(ctx, key, buf)
err = storePlainBlob(blob.ID, "damaged-", plaintext)
if err != nil {
return err
}
continue
}
}
if blob.IsCompressed() {
decompressed, err := dec.DecodeAll(plaintext, nil)
if err != nil {
Printf(" failed to decompress blob %v\n", blob.ID)
}
if decompressed != nil {
plaintext = decompressed
}
}
id := restic.Hash(plaintext)
var prefix string
if !id.Equal(blob.ID) {
Printf(" successfully %vdecrypted blob (length %v), hash is %v, ID does not match, wanted %v\n", outputPrefix, len(plaintext), id, blob.ID)
prefix = "wrong-hash-"
} else {
Printf(" successfully %vdecrypted blob (length %v), hash is %v, ID matches\n", outputPrefix, len(plaintext), id)
prefix = "correct-"
}
if extractPack {
err = storePlainBlob(id, filePrefix+prefix, plaintext)
if err != nil {
return err
}
}
if reuploadBlobs {
_, _, _, err := repo.SaveBlob(ctx, blob.Type, plaintext, id, true)
if err != nil {
return err
}
Printf(" uploaded %v %v\n", blob.Type, id)
}
}
if reuploadBlobs {
err := repo.Flush(ctx)
if err != nil {
return err
}
}
return nil
}
func storePlainBlob(id restic.ID, prefix string, plain []byte) error {
filename := fmt.Sprintf("%s%s.bin", prefix, id)
f, err := os.Create(filename)
if err != nil {
return err
}
_, err = f.Write(plain)
if err != nil {
_ = f.Close()
return err
}
err = f.Close()
if err != nil {
return err
}
Printf("decrypt of blob %v stored at %v\n", id, filename)
return nil
}
func runDebugExamine(ctx context.Context, gopts GlobalOptions, args []string) error {
repo, err := OpenRepository(ctx, gopts)
if err != nil {
return err
}
ids := make([]restic.ID, 0)
for _, name := range args {
id, err := restic.ParseID(name)
if err != nil {
id, err = restic.Find(ctx, repo.Backend(), restic.PackFile, name)
if err != nil {
Warnf("error: %v\n", err)
continue
}
}
ids = append(ids, id)
}
if len(ids) == 0 {
return errors.Fatal("no pack files to examine")
}
if !gopts.NoLock {
var lock *restic.Lock
lock, ctx, err = lockRepo(ctx, repo)
defer unlockRepo(lock)
if err != nil {
return err
}
}
err = repo.LoadIndex(ctx)
if err != nil {
return err
}
for _, id := range ids {
err := examinePack(ctx, repo, id)
if err != nil {
Warnf("error: %v\n", err)
}
if err == context.Canceled {
break
}
}
return nil
}
func examinePack(ctx context.Context, repo restic.Repository, id restic.ID) error {
Printf("examine %v\n", id)
h := restic.Handle{
Type: restic.PackFile,
Name: id.String(),
}
fi, err := repo.Backend().Stat(ctx, h)
if err != nil {
return err
}
Printf(" file size is %v\n", fi.Size)
buf, err := backend.LoadAll(ctx, nil, repo.Backend(), h)
if err != nil {
return err
}
gotID := restic.Hash(buf)
if !id.Equal(gotID) {
Printf(" wanted hash %v, got %v\n", id, gotID)
} else {
Printf(" hash for file content matches\n")
}
Printf(" ========================================\n")
Printf(" looking for info in the indexes\n")
blobsLoaded := false
// examine all data the indexes have for the pack file
for b := range repo.Index().ListPacks(ctx, restic.NewIDSet(id)) {
blobs := b.Blobs
if len(blobs) == 0 {
continue
}
checkPackSize(blobs, fi.Size)
err = loadBlobs(ctx, repo, id, blobs)
if err != nil {
Warnf("error: %v\n", err)
} else {
blobsLoaded = true
}
}
Printf(" ========================================\n")
Printf(" inspect the pack itself\n")
blobs, _, err := repo.ListPack(ctx, id, fi.Size)
if err != nil {
return fmt.Errorf("pack %v: %v", id.Str(), err)
}
checkPackSize(blobs, fi.Size)
if !blobsLoaded {
return loadBlobs(ctx, repo, id, blobs)
}
return nil
}
func checkPackSize(blobs []restic.Blob, fileSize int64) {
// track current size and offset
var size, offset uint64
sort.Slice(blobs, func(i, j int) bool {
return blobs[i].Offset < blobs[j].Offset
})
for _, pb := range blobs {
Printf(" %v blob %v, offset %-6d, raw length %-6d\n", pb.Type, pb.ID, pb.Offset, pb.Length)
if offset != uint64(pb.Offset) {
Printf(" hole in file, want offset %v, got %v\n", offset, pb.Offset)
}
offset = uint64(pb.Offset + pb.Length)
size += uint64(pb.Length)
}
size += uint64(pack.CalculateHeaderSize(blobs))
if uint64(fileSize) != size {
Printf(" file sizes do not match: computed %v, file size is %v\n", size, fileSize)
} else {
Printf(" file sizes match\n")
}
}