Role of Lawyers

Was having this discussion about how the defense lawyer for Kasab was trying to stall his case. For that I got one reply that "Thats the job of Defense lawyer". But is it?
Well I dont know what was the aim of our constitution or what is the legal point of view but here is what I feel:
Lawyers are just means who help the court in reaching the truth. Aim of every lawyer whether prosecution or defense is to find the truth. The only difference is that a prosecution lawyer will hear one side of the story while defence lawyer will hear out accused side of story. This system shall just ensure that judgement is reached without taking both sides of view. Role of defence lawyer is not to defend the client. Its just to help him present his side of the case. Also care should be taken of lawyer-client confidentiality (whatever that might be). It should not be misused to save the client even by performing illegal acts.
As in this case stalling the case by presenting stupid facts is not part of his job.

I dont know what exactly is the law in this regard but this is how I feel.