As long as it comes with VAT bill with seller CST and TIN number no problem with warranty.
I have bought 4 sony items(phones ps camera) online, only the camera shutter button gave problem changed free of charge under warranty.
flipkart, amazon, snapdeal all have authorized sony sellers, the ones who sell imported sony items its mentioned in the ad/ listing. Just be thorough, contact the seller by phone. eBay sellers always mention whether item comes with seller warranty or manufacturer warranty.
Grey market imports are not covered under warranty.