Found in 2 comments on Hacker News
senozhatsky · 2018-11-14
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Speaking of the Linux kernel related books, I'd probably mention, Understanding The Linux Kernel [0] and Linux Kernel Development [1]. The LDDv4 is not going to happen any time soon; it seems there are no plans for a new edition at all.
[0] https://www.amazon.com/Understanding-Linux-Kernel-Third-Daniel/dp/0596005652 [1] https://www.amazon.com/Linux-Kernel-Development-Robert-Love/dp/0672329468 
It's very hard and dense to read, but I don't think there's a better book out there about a networking stack implementation.
It might be too much implementation-focused for your taste though (it was for mine), in which case one of the other books more focused on protocols (already suggested in other comments) might be a better choice.