TCP_CONGCTL(9)

💅 TCP_CONGCTL(9) 💅

okay so bestie, welcome to the Kernel Developer's Manual page for tcp_congctl — yes that's the section 9 one, kernel dev territory, put your big-girl hat on 🎀

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✨ NAME ✨

tcp_congctl — the TCP congestion control API, aka the plug-and-play system for congestion control algorithms 🦋

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✨ SYNOPSIS ✨

#include <netinet/tcp_congctl.h>

int
tcp_congctl_register(const char *, struct tcp_congctl *);

int
tcp_congctl_unregister(const char *);

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✨ DESCRIPTION ✨

so the tcp_congctrl API is literally the whole vibe for adding or removing TCP congestion control algorithms on-the-fly and for modularizing them 💫 it's giving hot-swappable networking, no cap. it includes basically two functions:

• tcp_congctl_register(const char *, struct tcp_congctl *) — registers a new congestion control algorithm, slay 👑 the struct tcp_congctl argument must contain a list of callbacks like the following:

struct tcp_congctl {
        int  (*fast_retransmit)(struct tcpcb *,
            struct tcphdr *);
        void (*slow_retransmit)(struct tcpcb *);
        void (*fast_retransmit_newack)(struct tcpcb *,
            struct tcphdr *);
        void (*newack)(struct tcpcb *,
            struct tcphdr *);
        void (*cong_exp)(struct tcpcb *);
};

• tcp_congctl_unregister(const char *) — if found, unregisters the selected TCP congestion control algorithm. bye bestie 👋

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✨ RETURN VALUES ✨

tcp_congctl_register() and tcp_congctl_unregister() both return 0 when there is no error 💖 zero means iconic, zero means we ate.

• if the name is already registered, tcp_congctl_register() will return EEXIST 🙈 (bestie that name is taken)
• tcp_congctl_unregister() can return ENOENT if there is no congestion control algorithm by that name 😭 (ghosted, doesn't exist)
• and it can return EBUSY if the matched algorithm is being used by userspace applications 💀 (can't unregister it, it's literally in a relationship with a userspace app right now)

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✨ FILES ✨

• implementation is in sys/netinet/tcp_congctl.c 🌸
• the interface is in sys/netinet/tcp_congctl.h 🌸

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✨ SEE ALSO ✨

• tcp(4) 🔥

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and that's the whole page, no notes 🫶 this one's from Debian, dated October 15, 2006 — yes she's an older queen but she still slays, periodt 💅✨