refactor middleware and cache in an attempt of clarifying its operation

api/middleware/middleware.go

@@ -10,11 +10,15 @@ import (
 	log "github.com/sirupsen/logrus"
 )
 
-var datasetsKey = "datasets"
+// requestContextKey holds a name for the request context storage key
+// which is used to store and get the permissions after passing middleware
+const requestContextKey = "requestContextKey"
 
 // TokenMiddleware performs access token verification and validation
 // JWTs are verified and validated by the app, opaque tokens are sent to AAI for verification
-// Successful auth results in list of authorised datasets
+// Successful auth results in list of authorised datasets.
+// The datasets are stored into a session cache for subsequent requests, and also
+// to the current request context for use in the endpoints.
 func TokenMiddleware() gin.HandlerFunc {
 
 	return func(c *gin.Context) {
@@ -23,11 +27,11 @@ func TokenMiddleware() gin.HandlerFunc {
 		if err != nil {
 			log.Debugf("no session cookie received")
 		}
-		var datasetCache session.DatasetCache
+		var cache session.Cache
 		var exists bool
 		if sessionCookie != "" {
 			log.Debug("session cookie received")
-			datasetCache, exists = session.Get(sessionCookie)
+			cache, exists = session.Get(sessionCookie)
 		}
 
 		if !exists {
@@ -57,14 +61,11 @@ func TokenMiddleware() gin.HandlerFunc {
 			// 200 OK with [] empty dataset list, when listing datasets (use case for sda-filesystem download tool)
 			// 404 dataset not found, when listing files from a dataset
 			// 401 unauthorised, when downloading a file
-			datasets := auth.GetPermissions(*visas)
-			datasetCache = session.DatasetCache{
-				Datasets: datasets,
-			}
+			cache.Datasets = auth.GetPermissions(*visas)
 
 			// Start a new session and store datasets under the session key
 			key := session.NewSessionKey()
-			session.Set(key, datasetCache)
+			session.Set(key, cache)
 			c.SetCookie(config.Config.Session.Name, // name
 				key, // value
 				int(config.Config.Session.Expiration)/1e9, // max age
@@ -77,31 +78,25 @@ func TokenMiddleware() gin.HandlerFunc {
 		}
 
 		// Store dataset list to request context, for use in the endpoint handlers
-		c = storeDatasets(c, datasetCache)
+		log.Debugf("storing %v to request context", cache)
+		c.Set(requestContextKey, cache)
 
 		// Forward request to the next endpoint handler
 		c.Next()
 	}
 
 }
 
-// storeDatasets stores the dataset list to the request context
-func storeDatasets(c *gin.Context, datasets session.DatasetCache) *gin.Context {
-	log.Debugf("storing %v datasets to request context", datasets)
-
-	c.Set(datasetsKey, datasets)
-
-	return c
-}
-
-// GetDatasets extracts the dataset list from the request context
-var GetDatasets = func(c *gin.Context) session.DatasetCache {
-	var datasetCache session.DatasetCache
-	cached, exists := c.Get(datasetsKey)
+// GetCacheFromContext is a helper function that endpoints can use to get data
+// stored to the *current* request context (not the session storage).
+// The request context was populated by the middleware, which in turn uses the session storage.
+var GetCacheFromContext = func(c *gin.Context) session.Cache {
+	var cache session.Cache
+	cached, exists := c.Get(requestContextKey)
 	if exists {
-		datasetCache = cached.(session.DatasetCache)
+		cache = cached.(session.Cache)
 	}
 	log.Debugf("returning %v from request context", cached)
 
-	return datasetCache
+	return cache
 }

api/middleware/middleware_test.go

@@ -182,8 +182,8 @@ func TestTokenMiddleware_Success_NoCache(t *testing.T) {
 	// Now that we are modifying the request context, we need to place the context test inside the handler
 	expectedDatasets := []string{"dataset1", "dataset2"}
 	testEndpointWithContextData := func(c *gin.Context) {
-		datasets, _ := c.Get(datasetsKey)
-		if !reflect.DeepEqual(datasets.(session.DatasetCache).Datasets, expectedDatasets) {
+		datasets, _ := c.Get(requestContextKey)
+		if !reflect.DeepEqual(datasets.(session.Cache).Datasets, expectedDatasets) {
 			t.Errorf("TestTokenMiddleware_Success_NoCache failed, got %s expected %s", datasets, expectedDatasets)
 		}
 	}
@@ -224,9 +224,9 @@ func TestTokenMiddleware_Success_FromCache(t *testing.T) {
 	originalGetCache := session.Get
 
 	// Substitute mock functions
-	session.Get = func(key string) (session.DatasetCache, bool) {
+	session.Get = func(key string) (session.Cache, bool) {
 		log.Warningf("session.Get %v", key)
-		cached := session.DatasetCache{
+		cached := session.Cache{
 			Datasets: []string{"dataset1", "dataset2"},
 		}
 
@@ -248,8 +248,8 @@ func TestTokenMiddleware_Success_FromCache(t *testing.T) {
 	// Now that we are modifying the request context, we need to place the context test inside the handler
 	expectedDatasets := []string{"dataset1", "dataset2"}
 	testEndpointWithContextData := func(c *gin.Context) {
-		datasets, _ := c.Get(datasetsKey)
-		if !reflect.DeepEqual(datasets.(session.DatasetCache).Datasets, expectedDatasets) {
+		datasets, _ := c.Get(requestContextKey)
+		if !reflect.DeepEqual(datasets.(session.Cache).Datasets, expectedDatasets) {
 			t.Errorf("TestTokenMiddleware_Success_FromCache failed, got %s expected %s", datasets, expectedDatasets)
 		}
 	}
@@ -284,13 +284,13 @@ func TestStoreDatasets(t *testing.T) {
 	c, _ := gin.CreateTestContext(w)
 
 	// Store data to request context
-	datasets := session.DatasetCache{
+	datasets := session.Cache{
 		Datasets: []string{"dataset1", "dataset2"},
 	}
-	modifiedContext := storeDatasets(c, datasets)
+	c.Set(requestContextKey, datasets)
 
 	// Verify that context has new data
-	storedDatasets := modifiedContext.Value(datasetsKey).(session.DatasetCache)
+	storedDatasets := c.Value(requestContextKey).(session.Cache)
 	if !reflect.DeepEqual(datasets, storedDatasets) {
 		t.Errorf("TestStoreDatasets failed, got %s, expected %s", storedDatasets, datasets)
 	}
@@ -304,13 +304,13 @@ func TestGetDatasets(t *testing.T) {
 	c, _ := gin.CreateTestContext(w)
 
 	// Store data to request context
-	datasets := session.DatasetCache{
+	datasets := session.Cache{
 		Datasets: []string{"dataset1", "dataset2"},
 	}
-	modifiedContext := storeDatasets(c, datasets)
+	c.Set(requestContextKey, datasets)
 
 	// Verify that context has new data
-	storedDatasets := GetDatasets(modifiedContext)
+	storedDatasets := GetCacheFromContext(c)
 	if !reflect.DeepEqual(datasets, storedDatasets) {
 		t.Errorf("TestStoreDatasets failed, got %s, expected %s", storedDatasets, datasets)
 	}

api/s3/s3.go

@@ -94,8 +94,8 @@ func ListBuckets(c *gin.Context) {
 	}
 
 	buckets := []Bucket{}
-	datasetCache := middleware.GetDatasets(c)
-	for _, dataset := range datasetCache.Datasets {
+	cache := middleware.GetCacheFromContext(c)
+	for _, dataset := range cache.Datasets {
 		datasetInfo, err := database.GetDatasetInfo(dataset)
 		if err != nil {
 			log.Errorf("Failed to get dataset information: %v", err)
@@ -123,8 +123,8 @@ func ListObjects(c *gin.Context) {
 	dataset := c.Param("dataset")
 
 	allowed := false
-	datasetCache := middleware.GetDatasets(c)
-	for _, known := range datasetCache.Datasets {
+	cache := middleware.GetCacheFromContext(c)
+	for _, known := range cache.Datasets {
 		if dataset == known {
 			allowed = true
 
@@ -244,8 +244,8 @@ func parseParams(c *gin.Context) *gin.Context {
 		path = string(protocolPattern.ReplaceAll([]byte(path), []byte("$1/$2")))
 	}
 
-	datasetCache := middleware.GetDatasets(c)
-	for _, dataset := range datasetCache.Datasets {
+	cache := middleware.GetCacheFromContext(c)
+	for _, dataset := range cache.Datasets {
 		// check that the path starts with the dataset name, but also that the
 		// path is only the dataset, or that the following character is a slash.
 		// This prevents wrong matches in cases like when one dataset name is a

api/sda/sda.go

@@ -35,10 +35,10 @@ func Datasets(c *gin.Context) {
 
 	// Retrieve dataset list from request context
 	// generated by the authentication middleware
-	datasetCache := middleware.GetDatasets(c)
+	cache := middleware.GetCacheFromContext(c)
 
 	// Return response
-	c.JSON(http.StatusOK, datasetCache.Datasets)
+	c.JSON(http.StatusOK, cache.Datasets)
 }
 
 // find looks for a dataset name in a list of datasets
@@ -60,11 +60,11 @@ var getFiles = func(datasetID string, ctx *gin.Context) ([]*database.FileInfo, i
 
 	// Retrieve dataset list from request context
 	// generated by the authentication middleware
-	datasetCache := middleware.GetDatasets(ctx)
+	cache := middleware.GetCacheFromContext(ctx)
 
 	log.Debugf("request to process files for dataset %s", sanitizeString(datasetID))
 
-	if find(datasetID, datasetCache.Datasets) {
+	if find(datasetID, cache.Datasets) {
 		// Get file metadata
 		files, err := database.GetFiles(datasetID)
 		if err != nil {
@@ -133,12 +133,12 @@ func Download(c *gin.Context) {
 	}
 
 	// Get datasets from request context, parsed previously by token middleware
-	datasetCache := middleware.GetDatasets(c)
+	cache := middleware.GetCacheFromContext(c)
 
 	// Verify user has permission to datafile
 	permission := false
-	for d := range datasetCache.Datasets {
-		if datasetCache.Datasets[d] == dataset {
+	for d := range cache.Datasets {
+		if cache.Datasets[d] == dataset {
 			permission = true
 
 			break