Does an old book count? If yes, I believe "TCP/IP Illustrated, Volume 2" is about the implementation.
Unless you're looking for kernel level implementation, you could take a look at userspace implementations. Google for "DPDK tcp ip" or something to that effect.
Operating System Design Volume 2: Internetworking with XINU, 1987. ISBN 0-13-637414-X 025
Shows how to add IP/UDP to a simple Unix-like OS. You might want to also read volume 1:
Operating System Design - The XINU Approach, Second Edition, 2015. ISBN 9781498712439
https://www.cs.purdue.edu/homes/comer/osbooks.html