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restic/internal/backend/rest/rest.go
2017-07-24 17:43:32 +02:00

352 lines
7.8 KiB
Go

package rest
import (
"context"
"encoding/json"
"fmt"
"io"
"io/ioutil"
"net/http"
"net/url"
"path"
"strings"
"golang.org/x/net/context/ctxhttp"
"github.com/restic/restic/internal/debug"
"github.com/restic/restic/internal/errors"
"github.com/restic/restic/internal/restic"
"github.com/restic/restic/internal/backend"
)
// make sure the rest backend implements restic.Backend
var _ restic.Backend = &restBackend{}
type restBackend struct {
url *url.URL
sem *backend.Semaphore
client *http.Client
backend.Layout
}
// Open opens the REST backend with the given config.
func Open(cfg Config) (restic.Backend, error) {
client := &http.Client{Transport: backend.Transport()}
sem, err := backend.NewSemaphore(cfg.Connections)
if err != nil {
return nil, err
}
// use url without trailing slash for layout
url := cfg.URL.String()
if url[len(url)-1] == '/' {
url = url[:len(url)-1]
}
be := &restBackend{
url: cfg.URL,
client: client,
Layout: &backend.RESTLayout{URL: url, Join: path.Join},
sem: sem,
}
return be, nil
}
// Create creates a new REST on server configured in config.
func Create(cfg Config) (restic.Backend, error) {
be, err := Open(cfg)
if err != nil {
return nil, err
}
_, err = be.Stat(context.TODO(), restic.Handle{Type: restic.ConfigFile})
if err == nil {
return nil, errors.Fatal("config file already exists")
}
url := *cfg.URL
values := url.Query()
values.Set("create", "true")
url.RawQuery = values.Encode()
resp, err := http.Post(url.String(), "binary/octet-stream", strings.NewReader(""))
if err != nil {
return nil, err
}
if resp.StatusCode != http.StatusOK {
return nil, errors.Fatalf("server response unexpected: %v (%v)", resp.Status, resp.StatusCode)
}
_, err = io.Copy(ioutil.Discard, resp.Body)
if err != nil {
return nil, err
}
err = resp.Body.Close()
if err != nil {
return nil, err
}
return be, nil
}
// Location returns this backend's location (the server's URL).
func (b *restBackend) Location() string {
return b.url.String()
}
// Save stores data in the backend at the handle.
func (b *restBackend) Save(ctx context.Context, h restic.Handle, rd io.Reader) (err error) {
if err := h.Valid(); err != nil {
return err
}
ctx, cancel := context.WithCancel(ctx)
defer cancel()
// make sure that client.Post() cannot close the reader by wrapping it
rd = ioutil.NopCloser(rd)
b.sem.GetToken()
resp, err := ctxhttp.Post(ctx, b.client, b.Filename(h), "binary/octet-stream", rd)
b.sem.ReleaseToken()
if resp != nil {
defer func() {
_, _ = io.Copy(ioutil.Discard, resp.Body)
e := resp.Body.Close()
if err == nil {
err = errors.Wrap(e, "Close")
}
}()
}
if err != nil {
return errors.Wrap(err, "client.Post")
}
if resp.StatusCode != 200 {
return errors.Errorf("server response unexpected: %v (%v)", resp.Status, resp.StatusCode)
}
return nil
}
// ErrIsNotExist is returned whenever the requested file does not exist on the
// server.
type ErrIsNotExist struct {
restic.Handle
}
func (e ErrIsNotExist) Error() string {
return fmt.Sprintf("%v does not exist", e.Handle)
}
// IsNotExist returns true if the error was caused by a non-existing file.
func (b *restBackend) IsNotExist(err error) bool {
err = errors.Cause(err)
_, ok := err.(ErrIsNotExist)
return ok
}
// Load returns a reader that yields the contents of the file at h at the
// given offset. If length is nonzero, only a portion of the file is
// returned. rd must be closed after use.
func (b *restBackend) Load(ctx context.Context, h restic.Handle, length int, offset int64) (io.ReadCloser, error) {
debug.Log("Load %v, length %v, offset %v", h, length, offset)
if err := h.Valid(); err != nil {
return nil, err
}
if offset < 0 {
return nil, errors.New("offset is negative")
}
if length < 0 {
return nil, errors.Errorf("invalid length %d", length)
}
req, err := http.NewRequest("GET", b.Filename(h), nil)
if err != nil {
return nil, errors.Wrap(err, "http.NewRequest")
}
byteRange := fmt.Sprintf("bytes=%d-", offset)
if length > 0 {
byteRange = fmt.Sprintf("bytes=%d-%d", offset, offset+int64(length)-1)
}
req.Header.Add("Range", byteRange)
debug.Log("Load(%v) send range %v", h, byteRange)
b.sem.GetToken()
resp, err := ctxhttp.Do(ctx, b.client, req)
b.sem.ReleaseToken()
if err != nil {
if resp != nil {
_, _ = io.Copy(ioutil.Discard, resp.Body)
_ = resp.Body.Close()
}
return nil, errors.Wrap(err, "client.Do")
}
if resp.StatusCode == http.StatusNotFound {
_ = resp.Body.Close()
return nil, ErrIsNotExist{h}
}
if resp.StatusCode != 200 && resp.StatusCode != 206 {
_ = resp.Body.Close()
return nil, errors.Errorf("unexpected HTTP response (%v): %v", resp.StatusCode, resp.Status)
}
return resp.Body, nil
}
// Stat returns information about a blob.
func (b *restBackend) Stat(ctx context.Context, h restic.Handle) (restic.FileInfo, error) {
if err := h.Valid(); err != nil {
return restic.FileInfo{}, err
}
b.sem.GetToken()
resp, err := ctxhttp.Head(ctx, b.client, b.Filename(h))
b.sem.ReleaseToken()
if err != nil {
return restic.FileInfo{}, errors.Wrap(err, "client.Head")
}
_, _ = io.Copy(ioutil.Discard, resp.Body)
if err = resp.Body.Close(); err != nil {
return restic.FileInfo{}, errors.Wrap(err, "Close")
}
if resp.StatusCode == http.StatusNotFound {
_ = resp.Body.Close()
return restic.FileInfo{}, ErrIsNotExist{h}
}
if resp.StatusCode != 200 {
return restic.FileInfo{}, errors.Errorf("unexpected HTTP response (%v): %v", resp.StatusCode, resp.Status)
}
if resp.ContentLength < 0 {
return restic.FileInfo{}, errors.New("negative content length")
}
bi := restic.FileInfo{
Size: resp.ContentLength,
}
return bi, nil
}
// Test returns true if a blob of the given type and name exists in the backend.
func (b *restBackend) Test(ctx context.Context, h restic.Handle) (bool, error) {
_, err := b.Stat(ctx, h)
if err != nil {
return false, nil
}
return true, nil
}
// Remove removes the blob with the given name and type.
func (b *restBackend) Remove(ctx context.Context, h restic.Handle) error {
if err := h.Valid(); err != nil {
return err
}
req, err := http.NewRequest("DELETE", b.Filename(h), nil)
if err != nil {
return errors.Wrap(err, "http.NewRequest")
}
b.sem.GetToken()
resp, err := ctxhttp.Do(ctx, b.client, req)
b.sem.ReleaseToken()
if err != nil {
return errors.Wrap(err, "client.Do")
}
if resp.StatusCode == http.StatusNotFound {
_ = resp.Body.Close()
return ErrIsNotExist{h}
}
if resp.StatusCode != 200 {
return errors.Errorf("blob not removed, server response: %v (%v)", resp.Status, resp.StatusCode)
}
_, err = io.Copy(ioutil.Discard, resp.Body)
if err != nil {
return errors.Wrap(err, "Copy")
}
return errors.Wrap(resp.Body.Close(), "Close")
}
// List returns a channel that yields all names of blobs of type t. A
// goroutine is started for this. If the channel done is closed, sending
// stops.
func (b *restBackend) List(ctx context.Context, t restic.FileType) <-chan string {
ch := make(chan string)
url := b.Dirname(restic.Handle{Type: t})
if !strings.HasSuffix(url, "/") {
url += "/"
}
b.sem.GetToken()
resp, err := ctxhttp.Get(ctx, b.client, url)
b.sem.ReleaseToken()
if resp != nil {
defer func() {
_, _ = io.Copy(ioutil.Discard, resp.Body)
e := resp.Body.Close()
if err == nil {
err = errors.Wrap(e, "Close")
}
}()
}
if err != nil {
close(ch)
return ch
}
dec := json.NewDecoder(resp.Body)
var list []string
if err = dec.Decode(&list); err != nil {
close(ch)
return ch
}
go func() {
defer close(ch)
for _, m := range list {
select {
case ch <- m:
case <-ctx.Done():
return
}
}
}()
return ch
}
// Close closes all open files.
func (b *restBackend) Close() error {
// this does not need to do anything, all open files are closed within the
// same function.
return nil
}