[begemot]

Isn't it a bad idea to retrieve any url since then an attacker could use this service to sql inject without leaving his IP on the victims log?

[JoachimSchipper]

Meh. There are plenty of open redirects out there anyway, and using one you made yourself has the disadvantage that you'll be visible in the Referrer logs.

[brown9-2]

I'd imagine most of these services just do GETs, which negates most of that possibility.