Redirect back to called URL after Login/Join

Since I have implemented Dolphin as my Main site, I use its user system to all over my sub domains.

I have Vanilla forums on my subdomain. Since I have implemented Single Sign-On. When the user clicks on vanilla login, they are redirected to dolphin site login page. When they logged in successfully, they are redirected to Profile page as per the Dolphin configuration. 
But I want them to be redirected back to Vanilla Forums after login. How to do that?

Similarly, I have some custom PHP page on my Dolphin folder which also uses Dolphin Login System. When a user visits that page, if they are not logged into  dolphin site then they are shown dolphin login page. After login, they are redirected to Profile page as per Dolphin configuration. I want them to be redirected back to the custom PHP page after login.

How to achieve this? How to redirect back to called URL after Login/Join?

Not sure, but I've seen similar offerings in the market.  Here's a possible solution: http://www.boonex.com/m/custom-redirects

There is also the Page Redirect module which gives many more options for redirecting : http://www.boonex.com/m/redirect

 This module has a single redirect page to be set to be redirected after login or logout which do not fulfill my need.

 This module is somehow good than http://www.boonex.com/m/custom-redirects because It has more option to choose from the list while the time of login but once set they will be redirected to their chosen page after login.
This can also be added to join page as said in the description, but every time member have to choose.
I want this be automatically done, something like this http://mydolphinwebsite.com/join.php?redirect=http://theurlfromwhichtheloginpageiscalled.com

Do you understand what I want to achieve? Is it possible? 

not sure about the modules as I have not used them. But just a few tips - you have to first somehow track the page that they came from. You can either use cookies or a session variable. then use this variable to plug into one of the modules like you want. Not sure how to replace the existing option with a hard coded referrer url though. this is just a quick thought on how you may get what you want.

ProfessorSr:

You exactly understood what I want to achieve. I don't have any redirect module. Cannot it be done directly through the code change? Help me!

ProfessorSr:

Are you working on this issue? Tell me, if you aren't then I will search for some other option.

Why are you making me wait for this? Why aren't you replying to my messages?

I saw ProfessorSr active these days. Hope he will comment something this time!