Make NuGet service index publicly accessible (#21242)

Addition to #20734, Fixes #20717

The `/index.json` endpoint needs to be accessible even if the registry
is private. The NuGet client uses this endpoint without
authentification.

The old fix only works if the NuGet cli is used with `--source <name>`
but not with `--source <url>/index.json`.

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

tests/integration/api_packages_nuget_test.go

@@ -19,6 +19,7 @@ import (
 	user_model "code.gitea.io/gitea/models/user"
 	nuget_module "code.gitea.io/gitea/modules/packages/nuget"
 	"code.gitea.io/gitea/modules/setting"
+	"code.gitea.io/gitea/modules/structs"
 	"code.gitea.io/gitea/routers/api/packages/nuget"
 	"code.gitea.io/gitea/tests"
 
@@ -66,39 +67,58 @@ func TestPackageNuGet(t *testing.T) {
 	t.Run("ServiceIndex", func(t *testing.T) {
 		defer tests.PrintCurrentTest(t)()
 
-		req := NewRequest(t, "GET", fmt.Sprintf("%s/index.json", url))
-		req = AddBasicAuthHeader(req, user.Name)
-		MakeRequest(t, req, http.StatusOK)
+		privateUser := unittest.AssertExistsAndLoadBean(t, &user_model.User{Visibility: structs.VisibleTypePrivate})
 
-		req = NewRequest(t, "GET", fmt.Sprintf("%s/index.json", url))
-		req = addNuGetAPIKeyHeader(req, token)
-		resp := MakeRequest(t, req, http.StatusOK)
+		cases := []struct {
+			Owner        string
+			UseBasicAuth bool
+			UseTokenAuth bool
+		}{
+			{privateUser.Name, false, false},
+			{privateUser.Name, true, false},
+			{privateUser.Name, false, true},
+			{user.Name, false, false},
+			{user.Name, true, false},
+			{user.Name, false, true},
+		}
 
-		var result nuget.ServiceIndexResponse
-		DecodeJSON(t, resp, &result)
+		for _, c := range cases {
+			url := fmt.Sprintf("/api/packages/%s/nuget", c.Owner)
 
-		assert.Equal(t, "3.0.0", result.Version)
-		assert.NotEmpty(t, result.Resources)
+			req := NewRequest(t, "GET", fmt.Sprintf("%s/index.json", url))
+			if c.UseBasicAuth {
+				req = AddBasicAuthHeader(req, user.Name)
+			} else if c.UseTokenAuth {
+				req = addNuGetAPIKeyHeader(req, token)
+			}
+			resp := MakeRequest(t, req, http.StatusOK)
 
-		root := setting.AppURL + url[1:]
-		for _, r := range result.Resources {
-			switch r.Type {
-			case "SearchQueryService":
-				fallthrough
-			case "SearchQueryService/3.0.0-beta":
-				fallthrough
-			case "SearchQueryService/3.0.0-rc":
-				assert.Equal(t, root+"/query", r.ID)
-			case "RegistrationsBaseUrl":
-				fallthrough
-			case "RegistrationsBaseUrl/3.0.0-beta":
-				fallthrough
-			case "RegistrationsBaseUrl/3.0.0-rc":
-				assert.Equal(t, root+"/registration", r.ID)
-			case "PackageBaseAddress/3.0.0":
-				assert.Equal(t, root+"/package", r.ID)
-			case "PackagePublish/2.0.0":
-				assert.Equal(t, root, r.ID)
+			var result nuget.ServiceIndexResponse
+			DecodeJSON(t, resp, &result)
+
+			assert.Equal(t, "3.0.0", result.Version)
+			assert.NotEmpty(t, result.Resources)
+
+			root := setting.AppURL + url[1:]
+			for _, r := range result.Resources {
+				switch r.Type {
+				case "SearchQueryService":
+					fallthrough
+				case "SearchQueryService/3.0.0-beta":
+					fallthrough
+				case "SearchQueryService/3.0.0-rc":
+					assert.Equal(t, root+"/query", r.ID)
+				case "RegistrationsBaseUrl":
+					fallthrough
+				case "RegistrationsBaseUrl/3.0.0-beta":
+					fallthrough
+				case "RegistrationsBaseUrl/3.0.0-rc":
+					assert.Equal(t, root+"/registration", r.ID)
+				case "PackageBaseAddress/3.0.0":
+					assert.Equal(t, root+"/package", r.ID)
+				case "PackagePublish/2.0.0":
+					assert.Equal(t, root, r.ID)
+				}
 			}
 		}
 	})