Add merge slash middleware

There are code in the core component to conditionally execute code based
on the pattern of url path, and different ingress controller or reverse
proxy may handle the dup slashes in the url path differently.
This commit merge dup slashes in the url paths to make things more
consistent.

Signed-off-by: Daniel Jiang <jiangd@vmware.com>

src/core/middlewares/middlewares.go

@@ -24,6 +24,7 @@ import (
 	"github.com/goharbor/harbor/src/server/middleware/artifactinfo"
 	"github.com/goharbor/harbor/src/server/middleware/csrf"
 	"github.com/goharbor/harbor/src/server/middleware/log"
+	"github.com/goharbor/harbor/src/server/middleware/mergeslash"
 	"github.com/goharbor/harbor/src/server/middleware/metric"
 	"github.com/goharbor/harbor/src/server/middleware/notification"
 	"github.com/goharbor/harbor/src/server/middleware/orm"
@@ -77,6 +78,7 @@ var (
 // MiddleWares returns global middlewares
 func MiddleWares() []beego.MiddleWare {
 	return []beego.MiddleWare{
+		mergeslash.Middleware(),
 		metric.Middleware(),
 		requestid.Middleware(),
 		log.Middleware(),

src/server/middleware/mergeslash/mergeslash.go

@@ -0,0 +1,19 @@
+package mergeslash
+
+import (
+	"net/http"
+	"regexp"
+
+	"github.com/goharbor/harbor/src/server/middleware"
+)
+
+var multiSlash = regexp.MustCompile(`(/+)`)
+
+// Middleware creates the middleware to merge slashes in the URL path of the request
+func Middleware(skippers ...middleware.Skipper) func(http.Handler) http.Handler {
+	return middleware.New(func(w http.ResponseWriter, r *http.Request, next http.Handler) {
+		path := multiSlash.ReplaceAll([]byte(r.URL.Path), []byte("/"))
+		r.URL.Path = string(path)
+		next.ServeHTTP(w, r)
+	}, skippers...)
+}

src/server/middleware/mergeslash/mergeslash_test.go

@@ -0,0 +1,52 @@
+package mergeslash
+
+import (
+	"net/http"
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+type handler struct {
+	path string
+}
+
+func (h *handler) ServeHTTP(w http.ResponseWriter, req *http.Request) {
+	h.path = req.URL.Path
+	w.WriteHeader(200)
+}
+
+func TestMergeSlash(t *testing.T) {
+	next := &handler{}
+	rec := httptest.NewRecorder()
+	req1, _ := http.NewRequest(http.MethodGet, "https://test.local/api/v2.0/systeminfo/", nil)
+	req2, _ := http.NewRequest(http.MethodGet, "https://test.local/v2//////_catalog", nil)
+	req3, _ := http.NewRequest(http.MethodPost, "https://test.local/v2/library///////ubuntu//blobs/uploads///////", nil)
+	req4, _ := http.NewRequest(http.MethodGet, "https://test.local//api/v2.0///////artifacts?scan_overview=false", nil)
+	cases := []struct {
+		req          *http.Request
+		expectedPath string
+	}{
+		{
+			req:          req1,
+			expectedPath: "/api/v2.0/systeminfo/",
+		},
+		{
+			req:          req2,
+			expectedPath: "/v2/_catalog",
+		},
+		{
+			req:          req3,
+			expectedPath: "/v2/library/ubuntu/blobs/uploads/",
+		},
+		{
+			req:          req4,
+			expectedPath: "/api/v2.0/artifacts",
+		},
+	}
+	for _, tt := range cases {
+		Middleware()(next).ServeHTTP(rec, tt.req)
+		assert.Equal(t, tt.expectedPath, next.path)
+	}
+}