[PLT-5639] Show a message when invited addresses are blocked (#6691)

* Show a message when invited addresses are blocked

When using the "Send Email Invite" functionality. Emails were sent to
domains that were not on the `RestrictCreationToDomains` list. This
would lead to users getting a message that they can't create an account
if they follow the link in the email.

This commit will check the email addresses before the mails are sent and
warn the user typing them in which ones are blocked.

* Add unit test for domain restrictions on invite

* Invite Member: Clear serverError on toggle

1 files changed, 26 insertions, 7 deletions

diff --git a/app/team.go b/app/team.go
index 94523f8b5..be15b8a39 100644
--- a/app/team.go
+++ b/app/team.go
@@ -55,13 +55,8 @@ func CreateTeamWithUser(team *model.Team, userId string) (*model.Team, *model.Ap
 	return rteam, nil
 }
 
-func isTeamEmailAllowed(user *model.User) bool {
-	email := strings.ToLower(user.Email)
-
-	if len(user.AuthService) > 0 && len(*user.AuthData) > 0 {
-		return true
-	}
-
+func isTeamEmailAddressAllowed(email string) bool {
+	email = strings.ToLower(email)
 	// commas and @ signs are optional
 	// can be in the form of "@corp.mattermost.com, mattermost.com mattermost.org" -> corp.mattermost.com mattermost.com mattermost.org
 	domains := strings.Fields(strings.TrimSpace(strings.ToLower(strings.Replace(strings.Replace(utils.Cfg.TeamSettings.RestrictCreationToDomains, "@", " ", -1), ",", " ", -1))))
@@ -81,6 +76,16 @@ func isTeamEmailAllowed(user *model.User) bool {
 	return true
 }
 
+func isTeamEmailAllowed(user *model.User) bool {
+	email := strings.ToLower(user.Email)
+
+	if len(user.AuthService) > 0 && len(*user.AuthData) > 0 {
+		return true
+	}
+
+	return isTeamEmailAddressAllowed(email)
+}
+
 func UpdateTeam(team *model.Team) (*model.Team, *model.AppError) {
 	var oldTeam *model.Team
 	var err *model.AppError
@@ -621,6 +626,20 @@ func InviteNewUsersToTeam(emailList []string, teamId, senderId string) *model.Ap
 		return err
 	}
 
+	var invalidEmailList []string
+
+	for _, email := range emailList {
+		if ! isTeamEmailAddressAllowed(email) {
+			invalidEmailList = append(invalidEmailList, email)
+		}
+	}
+
+	if len(invalidEmailList) > 0 {
+		s := strings.Join(invalidEmailList, ", ")
+		err := model.NewAppError("InviteNewUsersToTeam", "api.team.invite_members.invalid_email.app_error", map[string]interface{}{"Addresses": s}, "", http.StatusBadRequest)
+		return err
+	}
+
 	tchan := Srv.Store.Team().Get(teamId)
 	uchan := Srv.Store.User().Get(senderId)