mirror of
https://github.com/restic/restic.git
synced 2024-09-10 21:24:06 +02:00
441 lines
11 KiB
Go
441 lines
11 KiB
Go
package rest
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import (
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"context"
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"encoding/json"
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"fmt"
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"hash"
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"io"
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"net/http"
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"net/url"
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"path"
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"strings"
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"github.com/restic/restic/internal/backend"
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"github.com/restic/restic/internal/backend/layout"
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"github.com/restic/restic/internal/backend/location"
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"github.com/restic/restic/internal/backend/util"
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"github.com/restic/restic/internal/debug"
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"github.com/restic/restic/internal/errors"
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)
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// make sure the rest backend implements backend.Backend
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var _ backend.Backend = &Backend{}
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// Backend uses the REST protocol to access data stored on a server.
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type Backend struct {
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url *url.URL
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connections uint
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client http.Client
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layout.Layout
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}
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// restError is returned whenever the server returns a non-successful HTTP status.
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type restError struct {
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backend.Handle
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StatusCode int
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Status string
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}
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func (e *restError) Error() string {
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if e.StatusCode == http.StatusNotFound && e.Handle.Type.String() != "invalid" {
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return fmt.Sprintf("%v does not exist", e.Handle)
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}
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return fmt.Sprintf("unexpected HTTP response (%v): %v", e.StatusCode, e.Status)
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}
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func NewFactory() location.Factory {
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return location.NewHTTPBackendFactory("rest", ParseConfig, StripPassword, Create, Open)
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}
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// the REST API protocol version is decided by HTTP request headers, these are the constants.
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const (
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ContentTypeV1 = "application/vnd.x.restic.rest.v1"
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ContentTypeV2 = "application/vnd.x.restic.rest.v2"
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)
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// Open opens the REST backend with the given config.
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func Open(_ context.Context, cfg Config, rt http.RoundTripper) (*Backend, error) {
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// use url without trailing slash for layout
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url := cfg.URL.String()
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if url[len(url)-1] == '/' {
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url = url[:len(url)-1]
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}
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be := &Backend{
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url: cfg.URL,
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client: http.Client{Transport: rt},
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Layout: &layout.RESTLayout{URL: url, Join: path.Join},
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connections: cfg.Connections,
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}
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return be, nil
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}
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func drainAndClose(resp *http.Response) error {
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_, err := io.Copy(io.Discard, resp.Body)
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cerr := resp.Body.Close()
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// return first error
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if err != nil {
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return errors.Errorf("drain: %w", err)
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}
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return cerr
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}
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// Create creates a new REST on server configured in config.
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func Create(ctx context.Context, cfg Config, rt http.RoundTripper) (*Backend, error) {
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be, err := Open(ctx, cfg, rt)
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if err != nil {
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return nil, err
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}
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_, err = be.Stat(ctx, backend.Handle{Type: backend.ConfigFile})
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if err == nil {
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return nil, errors.New("config file already exists")
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}
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url := *cfg.URL
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values := url.Query()
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values.Set("create", "true")
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url.RawQuery = values.Encode()
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resp, err := be.client.Post(url.String(), "binary/octet-stream", strings.NewReader(""))
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if err != nil {
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return nil, err
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}
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if err := drainAndClose(resp); err != nil {
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return nil, err
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}
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if resp.StatusCode != http.StatusOK {
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return nil, &restError{backend.Handle{}, resp.StatusCode, resp.Status}
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}
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return be, nil
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}
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func (b *Backend) Connections() uint {
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return b.connections
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}
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// Location returns this backend's location (the server's URL).
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func (b *Backend) Location() string {
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return b.url.String()
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}
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// Hasher may return a hash function for calculating a content hash for the backend
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func (b *Backend) Hasher() hash.Hash {
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return nil
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}
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// HasAtomicReplace returns whether Save() can atomically replace files
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func (b *Backend) HasAtomicReplace() bool {
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// rest-server prevents overwriting
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return false
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}
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// Save stores data in the backend at the handle.
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func (b *Backend) Save(ctx context.Context, h backend.Handle, rd backend.RewindReader) error {
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ctx, cancel := context.WithCancel(ctx)
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defer cancel()
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// make sure that client.Post() cannot close the reader by wrapping it
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req, err := http.NewRequestWithContext(ctx,
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http.MethodPost, b.Filename(h), io.NopCloser(rd))
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if err != nil {
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return errors.WithStack(err)
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}
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req.Header.Set("Content-Type", "application/octet-stream")
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req.Header.Set("Accept", ContentTypeV2)
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// explicitly set the content length, this prevents chunked encoding and
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// let's the server know what's coming.
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req.ContentLength = rd.Length()
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resp, err := b.client.Do(req)
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if err != nil {
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return errors.WithStack(err)
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}
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if err := drainAndClose(resp); err != nil {
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return err
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}
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if resp.StatusCode != http.StatusOK {
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return &restError{h, resp.StatusCode, resp.Status}
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}
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return nil
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}
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// IsNotExist returns true if the error was caused by a non-existing file.
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func (b *Backend) IsNotExist(err error) bool {
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var e *restError
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return errors.As(err, &e) && e.StatusCode == http.StatusNotFound
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}
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func (b *Backend) IsPermanentError(err error) bool {
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if b.IsNotExist(err) {
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return true
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}
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var rerr *restError
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if errors.As(err, &rerr) {
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if rerr.StatusCode == http.StatusRequestedRangeNotSatisfiable || rerr.StatusCode == http.StatusUnauthorized || rerr.StatusCode == http.StatusForbidden {
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return true
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}
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}
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return false
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}
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// Load runs fn with a reader that yields the contents of the file at h at the
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// given offset.
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func (b *Backend) Load(ctx context.Context, h backend.Handle, length int, offset int64, fn func(rd io.Reader) error) error {
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r, err := b.openReader(ctx, h, length, offset)
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if err != nil {
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return err
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}
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err = fn(r)
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if err != nil {
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_ = r.Close() // ignore error here
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return err
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}
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// Note: readerat.ReadAt() (the fn) uses io.ReadFull() that doesn't
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// wait for EOF after reading body. Due to HTTP/2 stream multiplexing
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// and goroutine timings the EOF frame arrives from server (eg. rclone)
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// with a delay after reading body. Immediate close might trigger
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// HTTP/2 stream reset resulting in the *stream closed* error on server,
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// so we wait for EOF before closing body.
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var buf [1]byte
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_, err = r.Read(buf[:])
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if err == io.EOF {
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err = nil
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}
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if e := r.Close(); err == nil {
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err = e
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}
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return err
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}
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func (b *Backend) openReader(ctx context.Context, h backend.Handle, length int, offset int64) (io.ReadCloser, error) {
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req, err := http.NewRequestWithContext(ctx, "GET", b.Filename(h), nil)
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if err != nil {
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return nil, errors.WithStack(err)
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}
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byteRange := fmt.Sprintf("bytes=%d-", offset)
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if length > 0 {
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byteRange = fmt.Sprintf("bytes=%d-%d", offset, offset+int64(length)-1)
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}
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req.Header.Set("Range", byteRange)
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req.Header.Set("Accept", ContentTypeV2)
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resp, err := b.client.Do(req)
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if err != nil {
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return nil, errors.Wrap(err, "client.Do")
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}
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if resp.StatusCode != http.StatusOK && resp.StatusCode != http.StatusPartialContent {
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_ = drainAndClose(resp)
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return nil, &restError{h, resp.StatusCode, resp.Status}
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}
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if length > 0 && resp.ContentLength != int64(length) {
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return nil, &restError{h, http.StatusRequestedRangeNotSatisfiable, "partial out of bounds read"}
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}
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return resp.Body, nil
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}
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// Stat returns information about a blob.
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func (b *Backend) Stat(ctx context.Context, h backend.Handle) (backend.FileInfo, error) {
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req, err := http.NewRequestWithContext(ctx, http.MethodHead, b.Filename(h), nil)
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if err != nil {
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return backend.FileInfo{}, errors.WithStack(err)
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}
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req.Header.Set("Accept", ContentTypeV2)
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resp, err := b.client.Do(req)
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if err != nil {
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return backend.FileInfo{}, errors.WithStack(err)
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}
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if err = drainAndClose(resp); err != nil {
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return backend.FileInfo{}, err
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}
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if resp.StatusCode != http.StatusOK {
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return backend.FileInfo{}, &restError{h, resp.StatusCode, resp.Status}
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}
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if resp.ContentLength < 0 {
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return backend.FileInfo{}, errors.New("negative content length")
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}
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bi := backend.FileInfo{
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Size: resp.ContentLength,
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Name: h.Name,
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}
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return bi, nil
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}
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// Remove removes the blob with the given name and type.
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func (b *Backend) Remove(ctx context.Context, h backend.Handle) error {
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req, err := http.NewRequestWithContext(ctx, "DELETE", b.Filename(h), nil)
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if err != nil {
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return errors.WithStack(err)
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}
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req.Header.Set("Accept", ContentTypeV2)
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resp, err := b.client.Do(req)
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if err != nil {
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return errors.Wrap(err, "client.Do")
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}
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if err = drainAndClose(resp); err != nil {
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return err
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}
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if resp.StatusCode != http.StatusOK {
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return &restError{h, resp.StatusCode, resp.Status}
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}
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return nil
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}
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// List runs fn for each file in the backend which has the type t. When an
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// error occurs (or fn returns an error), List stops and returns it.
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func (b *Backend) List(ctx context.Context, t backend.FileType, fn func(backend.FileInfo) error) error {
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url := b.Dirname(backend.Handle{Type: t})
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if !strings.HasSuffix(url, "/") {
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url += "/"
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}
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req, err := http.NewRequestWithContext(ctx, http.MethodGet, url, nil)
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if err != nil {
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return errors.WithStack(err)
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}
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req.Header.Set("Accept", ContentTypeV2)
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resp, err := b.client.Do(req)
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if err != nil {
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return errors.Wrap(err, "List")
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}
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if resp.StatusCode == http.StatusNotFound {
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if !strings.HasPrefix(resp.Header.Get("Server"), "rclone/") {
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// ignore missing directories, unless the server is rclone. rclone
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// already ignores missing directories, but misuses "not found" to
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// report certain internal errors, see
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// https://github.com/rclone/rclone/pull/7550 for details.
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return drainAndClose(resp)
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}
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}
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if resp.StatusCode != http.StatusOK {
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_ = drainAndClose(resp)
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return &restError{backend.Handle{Type: t}, resp.StatusCode, resp.Status}
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}
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if resp.Header.Get("Content-Type") == ContentTypeV2 {
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err = b.listv2(ctx, resp, fn)
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} else {
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err = b.listv1(ctx, t, resp, fn)
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}
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if cerr := drainAndClose(resp); cerr != nil && err == nil {
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err = cerr
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}
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return err
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}
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// listv1 uses the REST protocol v1, where a list HTTP request (e.g. `GET
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// /data/`) only returns the names of the files, so we need to issue an HTTP
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// HEAD request for each file.
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func (b *Backend) listv1(ctx context.Context, t backend.FileType, resp *http.Response, fn func(backend.FileInfo) error) error {
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debug.Log("parsing API v1 response")
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dec := json.NewDecoder(resp.Body)
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var list []string
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if err := dec.Decode(&list); err != nil {
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return errors.Wrap(err, "Decode")
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}
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for _, m := range list {
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fi, err := b.Stat(ctx, backend.Handle{Name: m, Type: t})
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if err != nil {
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return err
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}
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if ctx.Err() != nil {
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return ctx.Err()
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}
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fi.Name = m
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err = fn(fi)
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if err != nil {
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return err
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}
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if ctx.Err() != nil {
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return ctx.Err()
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}
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}
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return ctx.Err()
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}
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// listv2 uses the REST protocol v2, where a list HTTP request (e.g. `GET
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// /data/`) returns the names and sizes of all files.
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func (b *Backend) listv2(ctx context.Context, resp *http.Response, fn func(backend.FileInfo) error) error {
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debug.Log("parsing API v2 response")
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dec := json.NewDecoder(resp.Body)
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var list []struct {
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Name string `json:"name"`
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Size int64 `json:"size"`
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}
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if err := dec.Decode(&list); err != nil {
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return errors.Wrap(err, "Decode")
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}
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for _, item := range list {
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if ctx.Err() != nil {
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return ctx.Err()
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}
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fi := backend.FileInfo{
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Name: item.Name,
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Size: item.Size,
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}
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err := fn(fi)
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if err != nil {
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return err
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}
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if ctx.Err() != nil {
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return ctx.Err()
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}
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}
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return ctx.Err()
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}
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// Close closes all open files.
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func (b *Backend) Close() error {
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// this does not need to do anything, all open files are closed within the
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// same function.
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return nil
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}
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// Delete removes all data in the backend.
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func (b *Backend) Delete(ctx context.Context) error {
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return util.DefaultDelete(ctx, b)
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}
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