Electronic Arts has open sourced the code to for the Command and Conquer Remastered Collection - to be released in the coming days - including Tiberian Dawn and Red Alert. The code for the two games is in one repo at https://github.com/electronicarts/CnC_Remastered_Collection and is released under the GPLv3 license.
Command and Conquer Remastered Collection is a new release developed Alongside the C&C Community with 4K Graphics, rebuilt Multiplayer, enhanced UI, and a new soundtrack by Frank Klepacki.