What is the ruling on someone who indirectly asks for charity for himself, by saying: "I know someone who needs charity," and then takes it for himself?

The default rule regarding begging people for money is prohibition, except in limited cases mentioned by the Prophet, peace and blessings be upon him, such as: undertaking a guarantee (diyah), or being afflicted by a calamity that swept away one's wealth, or suffering from poverty attested to by three wise men from his people. Anything other than that is unlawful gain.

As for someone who is appointed to distribute charity and is poor, it is not permissible for him to take from it for himself, because this violates trust. The one who appointed him gives him the money to distribute to others. If he does so, he must inform the owner of the money what he has done. If the owner approves, then so be it; otherwise, he is liable for what he took.