Network layer

Fragmentation

ip_defrag -> ip_frag_queue -> ip_frag_reasm
ip_fragment
iphdr->id, iphdr->frag_off

Route

IPv4 route lookup on Linux
* state structure
fib_info:route info
fib_config:
* add new rule
iproute2 …->inet_rtm_newroute()->fib_new_table()->fib_hash_table()
* Multi-time line
fib_create_info(): create a fib_info

dst

remove dst garbage collector logic
commit 222d7dbd258dad4cd5241c43ef818141fad5a87a
Author: Eric Dumazet edumazet@google.com
Date: Thu Sep 21 09:15:46 2017 -0700
net: prevent dst uses after free
In linux-4.13, Wei worked hard to convert dst to a traditional
refcounted model, removing GC.
commit 9e1437937807b0122e8da1ca8765be2adca9aee6
Author: Steffen Klassert steffen.klassert@secunet.com
Date: Tue Sep 11 10:31:15 2018 +0200
xfrm: Fix NULL pointer dereference when skb_dst_force clears the dst_entry.

IP header

rfc1122
IP option is fixed in a session icsk->icsk_ext_hdr_len;
is network header icsk->icsk_af_ops->net_header_len