Function call relationships in the tcp protocol stack during tcp three-way handshake in the Linux Kernel

Function call relationships in the tcp protocol stack during tcp three-way handshake in the Linux kernel-Linux general technology-Linux programming and kernel information. For more information, see the following. Recently, I need to modify a set of tcp protocol stacks. I simply looked at the function calling process of the kernel tcp protocol stack. It is just a rough process and I did not make a detailed investigation, take a closer look at the changes. in addition, I only read the tcp part, and none of the following ip addresses is viewed.

Here we will briefly talk about the function call relationship of the three-way handshake that begins with the tcp connection:

Client: (initiate a connection request)

Tcp_v4_connect-> tcp_connect_init
-> Tcp_transmit_skb-> icsk-> icsk_af_ops-> send_check
(Tcp_v4_send_check)
-> Icsk-> icsk_af_ops-> queue_xmit
(Ip_queue_xmit)
Send syn packets externally
-> Inet_csk_reset_xmit_timer

Set the new timer

If you have not received a response for a while:
Tcp_retransmit_timer-> tcp_retransmit_skb-> tcp_transmit_skb
The other operations are the same as above.

Server: (receives syn and returns syn/ack)
Tcp_v4_rcv-> tcp_v4_do_rcv
-> Tcp_v4_hnd_req
-> Tcp_rcv_state_process
-> Icsk-> icsk_af_ops-> conn_request
(Tcp_v4_conn_request)->
-> Tcp_v4_init_sequence
-> Tcp_v4_send_synack
-> Ip_build_and_send_pkt

This is not comprehensive, but it was just written out in a hurry.

Client: (receives syn/ack and returns ack)
Tcp_v4_rcv-> tcp_v4_do_rcv
-> Tcp_rcv_state_process
-> Tcp_rcv_synsent_state_process
-> Tcp_ack
-> Tcp_store_ts_recent
-> Tcp_initialize_rcv_mss
-> Tcp_send_ack
-> Tcp_transmit_skb
-> Tcp_urg
-> Tcp_data_snd_check

Server: (receives ack)
Tcp_v4_do_rcv
-> Tcp_v4_hnd_req
-> Tcp_check_req
-> Inet_sk (sk)-> icsk_af_ops-> syn_recv_sock
-> Tcp_rcv_state_process
-> Tcp_sequence

The above is the description of the function call relationship in the tcp protocol stack of the three-way handshake. Due to the rush in sorting, some problems may exist.