i am creating one getaway & hosted solution that redirect user on select payment method so user can't press place order button so it's creating problem in register checkout. customer not create or login on register checkout.now i want to create & login that customer Programmatically using detail present in quote on return of customer from that payment site.May be Magento have already have some methods. can any body helps. Thanks
You can find here a possible solution for autologin. The example in the answer shows how to login a customer on frontend by clicking a button on the backend, but the idea is the same.
But I wouldn't recommend what you are trying.
There is always the chance that someone mimics the response you get from the gateway and can just try random quote ids and log in as anyone else.
If you are attempting it, make sure you use some kind of secret key and not just the quote id or only data from the quote.