[GITEA] oauth2: use link_account page when email/username is missing (#1757)

Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/1757
Co-authored-by: Antonin Delpeuch <antonin@delpeuch.eu>
Co-committed-by: Antonin Delpeuch <antonin@delpeuch.eu>
(cherry picked from commit 0f6e0f9035)
(cherry picked from commit 779168a572)
(cherry picked from commit 29a2457321)
(cherry picked from commit a1edc2314d)
(cherry picked from commit cd01594610)
(cherry picked from commit 74db46b0f5)
(cherry picked from commit fd98f55204)
(cherry picked from commit 3099d0e281)
(cherry picked from commit 9fbbe61364)

routers/web/auth/oauth.go

@@ -951,10 +951,16 @@ func SignInOAuthCallback(ctx *context.Context) {
 			return
 		} else if !setting.Service.AllowOnlyInternalRegistration && setting.OAuth2Client.EnableAutoRegistration {
 			// create new user with details from oauth2 provider
-			var missingFields []string
 			if gothUser.UserID == "" {
-				missingFields = append(missingFields, "sub")
+				log.Error("OAuth2 Provider %s returned empty or missing field: UserID", authSource.Name)
+				if authSource.IsOAuth2() && authSource.Cfg.(*oauth2.Source).Provider == "openidConnect" {
+					log.Error("You may need to change the 'OPENID_CONNECT_SCOPES' setting to request all required fields")
+				}
+				err = fmt.Errorf("OAuth2 Provider %s returned empty or missing field: UserID", authSource.Name)
+				ctx.ServerError("CreateUser", err)
+				return
 			}
+			var missingFields []string
 			if gothUser.Email == "" {
 				missingFields = append(missingFields, "email")
 			}
@@ -962,12 +968,10 @@ func SignInOAuthCallback(ctx *context.Context) {
 				missingFields = append(missingFields, "nickname")
 			}
 			if len(missingFields) > 0 {
-				log.Error("OAuth2 Provider %s returned empty or missing fields: %s", authSource.Name, missingFields)
+				// we don't have enough information to create an account automatically,
-				if authSource.IsOAuth2() && authSource.Cfg.(*oauth2.Source).Provider == "openidConnect" {
+				// so we prompt the user for the remaining bits
-					log.Error("You may need to change the 'OPENID_CONNECT_SCOPES' setting to request all required fields")
+				log.Trace("OAuth2 Provider %s returned empty or missing fields: %s, prompting the user for them", authSource.Name, missingFields)
-				}
+				showLinkingLogin(ctx, gothUser)
-				err = fmt.Errorf("OAuth2 Provider %s returned empty or missing fields: %s", authSource.Name, missingFields)
-				ctx.ServerError("CreateUser", err)
 				return
 			}
 			uname, err := getUserName(&gothUser)

tests/integration/oauth_test.go

@@ -469,3 +469,30 @@ func TestSignInOAuthCallbackSignIn(t *testing.T) {
 	userAfterLogin := unittest.AssertExistsAndLoadBean(t, &user_model.User{ID: userGitLab.ID})
 	assert.Greater(t, userAfterLogin.LastLoginUnix, userGitLab.LastLoginUnix)
 }
+
+func TestSignUpViaOAuthWithMissingFields(t *testing.T) {
+	defer tests.PrepareTestEnv(t)()
+	// enable auto-creation of accounts via OAuth2
+	enableAutoRegistration := setting.OAuth2Client.EnableAutoRegistration
+	setting.OAuth2Client.EnableAutoRegistration = true
+	defer func() {
+		setting.OAuth2Client.EnableAutoRegistration = enableAutoRegistration
+	}()
+
+	// OAuth2 authentication source GitLab
+	gitlabName := "gitlab"
+	addAuthSource(t, authSourcePayloadGitLabCustom(gitlabName))
+	userGitLabUserID := "5678"
+
+	// The Goth User returned by the oauth2 integration is missing
+	// an email address, so we won't be able to automatically create a local account for it.
+	defer mockCompleteUserAuth(func(res http.ResponseWriter, req *http.Request) (goth.User, error) {
+		return goth.User{
+			Provider: gitlabName,
+			UserID:   userGitLabUserID,
+		}, nil
+	})()
+	req := NewRequest(t, "GET", fmt.Sprintf("/user/oauth2/%s/callback?code=XYZ&state=XYZ", gitlabName))
+	resp := MakeRequest(t, req, http.StatusSeeOther)
+	assert.Equal(t, test.RedirectURL(resp), "/user/link_account")
+}