core: Add ability to stop upload from post-receive hook (tus#279)

* First implementation of stopping an upload from the server

* Remove unnecessary json tag

* Use golang.org/x/net/context for support in Go < 1.7

cmd/tusd/cli/composer.go

@@ -5,10 +5,10 @@ import (
 
 	"github.com/tus/tusd"
 	"github.com/tus/tusd/filestore"
+	"github.com/tus/tusd/gcsstore"
 	"github.com/tus/tusd/limitedstore"
 	"github.com/tus/tusd/memorylocker"
 	"github.com/tus/tusd/s3store"
-	"github.com/tus/tusd/gcsstore"
 
 	"github.com/aws/aws-sdk-go/aws"
 	"github.com/aws/aws-sdk-go/aws/session"

cmd/tusd/cli/flags.go

@@ -6,26 +6,27 @@ import (
 )
 
 var Flags struct {
-	HttpHost          string
-	HttpPort          string
-	HttpSock          string
-	MaxSize           int64
-	UploadDir         string
-	StoreSize         int64
-	Basepath          string
-	Timeout           int64
-	S3Bucket          string
-	S3ObjectPrefix    string
-	S3Endpoint        string
-	GCSBucket         string
-	FileHooksDir      string
-	HttpHooksEndpoint string
-	HttpHooksRetry    int
-	HttpHooksBackoff  int
-	ShowVersion       bool
-	ExposeMetrics     bool
-	MetricsPath       string
-	BehindProxy       bool
+	HttpHost            string
+	HttpPort            string
+	HttpSock            string
+	MaxSize             int64
+	UploadDir           string
+	StoreSize           int64
+	Basepath            string
+	Timeout             int64
+	S3Bucket            string
+	S3ObjectPrefix      string
+	S3Endpoint          string
+	GCSBucket           string
+	FileHooksDir        string
+	HttpHooksEndpoint   string
+	HttpHooksRetry      int
+	HttpHooksBackoff    int
+	HooksStopUploadCode int
+	ShowVersion         bool
+	ExposeMetrics       bool
+	MetricsPath         string
+	BehindProxy         bool
 
 	FileHooksInstalled bool
 	HttpHooksInstalled bool
@@ -48,6 +49,7 @@ func ParseFlags() {
 	flag.StringVar(&Flags.HttpHooksEndpoint, "hooks-http", "", "An HTTP endpoint to which hook events will be sent to")
 	flag.IntVar(&Flags.HttpHooksRetry, "hooks-http-retry", 3, "Number of times to retry on a 500 or network timeout")
 	flag.IntVar(&Flags.HttpHooksBackoff, "hooks-http-backoff", 1, "Number of seconds to wait before retrying each retry")
+	flag.IntVar(&Flags.HooksStopUploadCode, "hooks-stop-code", 0, "Return code from post-receive hook which causes tusd to stop and delete the current upload. A zero value means that no uploads will be stopped")
 	flag.BoolVar(&Flags.ShowVersion, "version", false, "Print tusd version information")
 	flag.BoolVar(&Flags.ExposeMetrics, "expose-metrics", true, "Expose metrics about tusd usage")
 	flag.StringVar(&Flags.MetricsPath, "metrics-path", "/metrics", "Path under which the metrics endpoint will be accessible")

cmd/tusd/cli/hooks.go

@@ -109,13 +109,14 @@ func invokeHookSync(typ HookType, info tusd.FileInfo, captureOutput bool) ([]byt
 
 	output := []byte{}
 	err := error(nil)
+	returnCode := 0
 
 	if Flags.FileHooksInstalled {
-		output, err = invokeFileHook(name, typ, info, captureOutput)
+		output, returnCode, err = invokeFileHook(name, typ, info, captureOutput)
 	}
 
 	if Flags.HttpHooksInstalled {
-		output, err = invokeHttpHook(name, typ, info, captureOutput)
+		output, returnCode, err = invokeHttpHook(name, typ, info, captureOutput)
 	}
 
 	if err != nil {
@@ -125,18 +126,24 @@ func invokeHookSync(typ HookType, info tusd.FileInfo, captureOutput bool) ([]byt
 		logEv(stdout, "HookInvocationFinish", "type", string(typ), "id", info.ID)
 	}
 
+	if typ == HookPostReceive && Flags.HooksStopUploadCode != 0 && Flags.HooksStopUploadCode == returnCode {
+		logEv(stdout, "HookStopUpload", "id", info.ID)
+
+		info.StopUpload()
+	}
+
 	return output, err
 }
 
-func invokeHttpHook(name string, typ HookType, info tusd.FileInfo, captureOutput bool) ([]byte, error) {
+func invokeHttpHook(name string, typ HookType, info tusd.FileInfo, captureOutput bool) ([]byte, int, error) {
 	jsonInfo, err := json.Marshal(info)
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	req, err := http.NewRequest("POST", Flags.HttpHooksEndpoint, bytes.NewBuffer(jsonInfo))
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	req.Header.Set("Hook-Name", name)
@@ -152,27 +159,27 @@ func invokeHttpHook(name string, typ HookType, info tusd.FileInfo, captureOutput
 
 	resp, err := client.Do(req)
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 	defer resp.Body.Close()
 
 	body, err := ioutil.ReadAll(resp.Body)
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	if resp.StatusCode >= http.StatusBadRequest {
-		return body, hookError{fmt.Errorf("endpoint returned: %s", resp.Status), resp.StatusCode, body}
+		return body, resp.StatusCode, hookError{fmt.Errorf("endpoint returned: %s", resp.Status), resp.StatusCode, body}
 	}
 
 	if captureOutput {
-		return body, err
+		return body, resp.StatusCode, err
 	}
 
-	return nil, err
+	return nil, resp.StatusCode, err
 }
 
-func invokeFileHook(name string, typ HookType, info tusd.FileInfo, captureOutput bool) ([]byte, error) {
+func invokeFileHook(name string, typ HookType, info tusd.FileInfo, captureOutput bool) ([]byte, int, error) {
 	hookPath := Flags.FileHooksDir + string(os.PathSeparator) + name
 	cmd := exec.Command(hookPath)
 	env := os.Environ()
@@ -182,7 +189,7 @@ func invokeFileHook(name string, typ HookType, info tusd.FileInfo, captureOutput
 
 	jsonInfo, err := json.Marshal(info)
 	if err != nil {
-		return nil, err
+		return nil, 0, err
 	}
 
 	reader := bytes.NewReader(jsonInfo)
@@ -208,5 +215,7 @@ func invokeFileHook(name string, typ HookType, info tusd.FileInfo, captureOutput
 		err = nil
 	}
 
-	return output, err
+	returnCode := cmd.ProcessState.ExitCode()
+
+	return output, returnCode, err
 }

datastore.go

@@ -2,6 +2,8 @@ package tusd
 
 import (
 	"io"
+
+	"golang.org/x/net/context"
 )
 
 type MetaData map[string]string
@@ -25,6 +27,21 @@ type FileInfo struct {
 	// ordered slice containing the ids of the uploads of which the final upload
 	// will consist after concatenation.
 	PartialUploads []string
+
+	// stopUpload is the cancel function for the upload's context.Context. When
+	// invoked it will interrupt the writes to DataStore#WriteChunk.
+	stopUpload context.CancelFunc
+}
+
+// StopUpload interrupts an running upload from the server-side. This means that
+// the current request body is closed, so that the data store does not get any
+// more data. Furthermore, a response is sent to notify the client of the
+// interrupting and the upload is terminated (if supported by the data store),
+// so the upload cannot be resumed anymore.
+func (f FileInfo) StopUpload() {
+	if f.stopUpload != nil {
+		f.stopUpload()
+	}
 }
 
 type DataStore interface {

patch_test.go

@@ -485,4 +485,64 @@ func TestPatch(t *testing.T) {
 		_, more := <-c
 		a.False(more)
 	})
+
+	SubTest(t, "StopUpload", func(t *testing.T, store *MockFullDataStore) {
+		gomock.InOrder(
+			store.EXPECT().GetInfo("yes").Return(FileInfo{
+				ID:     "yes",
+				Offset: 0,
+				Size:   100,
+			}, nil),
+			store.EXPECT().WriteChunk("yes", int64(0), NewReaderMatcher("first ")).Return(int64(6), http.ErrBodyReadAfterClose),
+			store.EXPECT().Terminate("yes").Return(nil),
+		)
+
+		handler, _ := NewHandler(Config{
+			DataStore:            store,
+			NotifyUploadProgress: true,
+		})
+
+		c := make(chan FileInfo)
+		handler.UploadProgress = c
+
+		reader, writer := io.Pipe()
+		a := assert.New(t)
+
+		go func() {
+			writer.Write([]byte("first "))
+
+			info := <-c
+			info.StopUpload()
+
+			// Wait a short time to ensure that the goroutine in the PATCH
+			// handler has received and processed the stop event.
+			<-time.After(10 * time.Millisecond)
+
+			// Assert that the "request body" has been closed.
+			_, err := writer.Write([]byte("second "))
+			a.Equal(err, io.ErrClosedPipe)
+
+			// Close the upload progress handler so that the main goroutine
+			// can exit properly after waiting for this goroutine to finish.
+			close(handler.UploadProgress)
+		}()
+
+		(&httpTest{
+			Method: "PATCH",
+			URL:    "yes",
+			ReqHeader: map[string]string{
+				"Tus-Resumable": "1.0.0",
+				"Content-Type":  "application/offset+octet-stream",
+				"Upload-Offset": "0",
+			},
+			ReqBody: reader,
+			Code:    http.StatusBadRequest,
+			ResHeader: map[string]string{
+				"Upload-Offset": "",
+			},
+		}).Run(handler, t)
+
+		_, more := <-c
+		a.False(more)
+	})
 }

unrouted_handler.go

@@ -14,6 +14,8 @@ import (
 	"strings"
 	"sync/atomic"
 	"time"
+
+	"golang.org/x/net/context"
 )
 
 const UploadLengthDeferred = "1"
@@ -70,6 +72,7 @@ var (
 	ErrModifyFinal                      = NewHTTPError(errors.New("modifying a final upload is not allowed"), http.StatusForbidden)
 	ErrUploadLengthAndUploadDeferLength = NewHTTPError(errors.New("provided both Upload-Length and Upload-Defer-Length"), http.StatusBadRequest)
 	ErrInvalidUploadDeferLength         = NewHTTPError(errors.New("invalid Upload-Defer-Length header"), http.StatusBadRequest)
+	ErrUploadStoppedByServer            = NewHTTPError(errors.New("upload has been stopped by server"), http.StatusBadRequest)
 )
 
 // UnroutedHandler exposes methods to handle requests as part of the tus protocol,
@@ -535,14 +538,46 @@ func (handler *UnroutedHandler) writeChunk(id string, info FileInfo, w http.Resp
 		// Limit the data read from the request's body to the allowed maximum
 		reader := io.LimitReader(r.Body, maxSize)
 
+		// We use a context object to allow the hook system to cancel an upload
+		uploadCtx, stopUpload := context.WithCancel(context.Background())
+		info.stopUpload = stopUpload
+		// terminateUpload specifies whether the upload should be deleted after
+		// the write has finished
+		terminateUpload := false
+		// Cancel the context when the function exits to ensure that the goroutine
+		// is properly cleaned up
+		defer stopUpload()
+
+		go func() {
+			// Interrupt the Read() call from the request body
+			<-uploadCtx.Done()
+			terminateUpload = true
+			r.Body.Close()
+		}()
+
 		if handler.config.NotifyUploadProgress {
-			var stop chan<- struct{}
-			reader, stop = handler.sendProgressMessages(info, reader)
-			defer close(stop)
+			var stopProgressEvents chan<- struct{}
+			reader, stopProgressEvents = handler.sendProgressMessages(info, reader)
+			defer close(stopProgressEvents)
 		}
 
 		var err error
 		bytesWritten, err = handler.composer.Core.WriteChunk(id, offset, reader)
+		if terminateUpload && handler.composer.UsesTerminater {
+			if terminateErr := handler.terminateUpload(id, info); terminateErr != nil {
+				// We only log this error and not show it to the user since this
+				// termination error is not relevant to the uploading client
+				handler.log("UploadStopTerminateError", "id", id, "error", terminateErr.Error())
+			}
+		}
+
+		// The error "http: invalid Read on closed Body" is returned if we stop the upload
+		// while the data store is still reading. Since this is an implementation detail,
+		// we replace this error with a message saying that the upload has been stopped.
+		if err == http.ErrBodyReadAfterClose {
+			err = ErrUploadStoppedByServer
+		}
+
 		if err != nil {
 			return err
 		}
@@ -735,19 +770,33 @@ func (handler *UnroutedHandler) DelFile(w http.ResponseWriter, r *http.Request)
 		}
 	}
 
-	err = handler.composer.Terminater.Terminate(id)
+	err = handler.terminateUpload(id, info)
 	if err != nil {
 		handler.sendError(w, r, err)
 		return
 	}
 
 	handler.sendResp(w, r, http.StatusNoContent)
+}
+
+// terminateUpload passes a given upload to the DataStore's Terminater,
+// send the corresponding upload info on the TerminatedUploads channnel
+// and updates the statistics.
+// Note the the info argument is only needed if the terminated uploads
+// notifications are enabled.
+func (handler *UnroutedHandler) terminateUpload(id string, info FileInfo) error {
+	err := handler.composer.Terminater.Terminate(id)
+	if err != nil {
+		return err
+	}
 
 	if handler.config.NotifyTerminatedUploads {
 		handler.TerminatedUploads <- info
 	}
 
 	handler.Metrics.incUploadsTerminated()
+
+	return nil
 }
 
 // Send the error in the response body. The status code will be looked up in

utils_test.go

@@ -99,6 +99,11 @@ func (m readerMatcher) Matches(x interface{}) bool {
 	}
 
 	bytes, err := ioutil.ReadAll(input)
+	// Handle closed pipes similar to how EOF are handled by ioutil.ReadAll,
+	// we handle this error as if the stream ended normally.
+	if err == io.ErrClosedPipe {
+		err = nil
+	}
 	if err != nil {
 		panic(err)
 	}