1.\" $NetBSD: tcp_congctl.9,v 1.3 2006/10/15 17:48:07 rpaulo Exp $ 2.\" 3.\" Copyright (c) 2006 The NetBSD Foundation, Inc. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to The NetBSD Foundation 7.\" by Rui Paulo. 8.\" 9.\" Redistribution and use in source and binary forms, with or without 10.\" modification, are permitted provided that the following conditions 11.\" are met: 12.\" 1. Redistributions of source code must retain the above copyright 13.\" notice, this list of conditions and the following disclaimer. 14.\" 2. Redistributions in binary form must reproduce the above copyright 15.\" notice, this list of conditions and the following disclaimer in the 16.\" documentation and/or other materials provided with the distribution. 17.\" 3. All advertising materials mentioning features or use of this software 18.\" must display the following acknowledgement: 19.\" This product includes software developed by the NetBSD 20.\" Foundation, Inc. and its contributors. 21.\" 4. Neither the name of The NetBSD Foundation nor the names of its 22.\" contributors may be used to endorse or promote products derived 23.\" from this software without specific prior written permission. 24.\" 25.\" THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS 26.\" ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED 27.\" TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR 28.\" PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS 29.\" BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR 30.\" CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF 31.\" SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS 32.\" INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN 33.\" CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) 34.\" ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE 35.\" POSSIBILITY OF SUCH DAMAGE. 36.\" 37.Dd October 15, 2006 38.Dt TCP_CONGCTL 9 39.Os 40.Sh NAME 41.Nm tcp_congctl 42.Nd TCP congestion control API 43.Sh SYNOPSIS 44.In netinet/tcp_congctl.h 45.\" 46.Ft int 47.Fn tcp_congctl_register "const char *" "struct tcp_congctl *" 48.\" 49.Ft int 50.Fn tcp_congctl_unregister "const char *" 51.\" 52.Sh DESCRIPTION 53The 54.Nm tcp_congctrl 55API is used to add or remove TCP congestion control algorithms 56on-the-fly and to modularize them. 57It includes basically two functions: 58.Bl -tag -width "xxxxx" 59.It Fn tcp_congctl_register "const char *" "struct tcp_congctl *" 60Registers a new congestion control algorithm. 61The 62.Fa struct tcp_congctl 63argument must contain a list of callbacks like the following: 64.Bd -literal -offset indent 65struct tcp_congctl { 66 int (*fast_retransmit)(struct tcpcb *, 67 struct tcphdr *); 68 void (*slow_retransmit)(struct tcpcb *); 69 void (*fast_retransmit_newack)(struct tcpcb *, 70 struct tcphdr *); 71 void (*newack)(struct tcpcb *, 72 struct tcphdr *); 73 void (*cong_exp)(struct tcpcb *); 74}; 75.Ed 76.It Fn tcp_congctl_unregister "const char *" 77If found, unregister the selected TCP congestion control algorithm. 78.El 79.Sh RETURN VALUES 80.Fn tcp_congctl_register 81and 82.Fn tcp_congctl_unregister 83both return 84.Dv 0 85when there is no error. 86If the name is already registered, 87.Fn tcp_congctl_register 88will return 89.Er EEXIST . 90.Fn tcp_congctl_unregister 91can return 92.Er ENOENT 93if there is no congestion control algorithm by that name and can return 94.Er EBUSY 95if the matched algorithm is being used by userspace applications. 96.Sh FILES 97Implementation is in 98.Pa sys/netinet/tcp_congctl.c 99and the interface is in 100.Pa sys/netinet/tcp_congctl.h . 101.Sh SEE ALSO 102.Xr tcp 4 103