General string format for this protocol:
	length (1 byte)
	Actual description (length bytes)

Client Send:
	add_contribution (1)
		type:  1 byte, 1
		name:  20 bytes
		need_length:  1 byte
		answered_need:  need_length bytes
	
	struct add_contribution {
		uint8_t type = 1;
		char name[20];
		uint8_t need_length;
		char answered_need[255];
	} __attribute__((packed));

	// to send
	struct add_contribution my_food = {1, "Seth", 4, "fish"};

	write(client_socket, &my_food, 1 + 20 + 1 + my_food.need_length);
			
	query_needs
	query_offers

Server Send:
	accept_contribution
	remaining_needs
	accepted_offers