Using one ssl for multiple url

To avoid the security alert for users typing just 123.com (which all major browsers interpret as http://123.com) you can use:

   rule redir_to_https {
       redirect to "https://www.123.com/%u"
   }
   virtual 1.2.3.4:80 {
      use rule redir_to_https
   }

assuming that DNS name 123.com resolves to address 1.2.3.4.

There is unfortunately no cheaper solution than getting certificate for 123.com that would allow to prevent the certificate name mismatch security alert for users that type "https://123.com". Fortunately users are not very likely to do that.