: No, light would not gain infinite mass as it approaches the speed of light. First of all, it is important to remember the wave-particle duality of light. Light sometimes behaves like a photon, and sometimes like an electromagnetic wave. So, in reality, it is both. While gravity can affect photons, it cannot affect the other portion of light's nature, that of being a wave. Also, it is the quantum nature of particles to travel at the speed of light and faster without gaining infinite mass. The mechanics of this property are really, really wierd and extremely difficult, but the information is in books available to buy. For a simple answer about how particles can travel faster than light, see Steven Hawking's A Brief History of Time. It talks about the evaporation of black holes. However, this also starts going into the world of quantum mechanics. But I do wish you happy hunting in looking for further explanations on this matter. Good luck.

You mention the duality of light. You said that sometimes it behaves like a wave and other times a photon, this is incorrect. The duality of light is that sometimes it behaves like a particle and and a wave, and the combination of these two theories gives the idea that light consists of a packet of energy(ie.e the photon).