1.\" 2.\" Copyright (c) 2004 Bruce M. Simpson <bms@spc.org> 3.\" Copyright (c) 2004 Darron Broad <darron@kewl.org> 4.\" All rights reserved. 5.\" 6.\" Redistribution and use in source and binary forms, with or without 7.\" modification, are permitted provided that the following conditions 8.\" are met: 9.\" 1. Redistributions of source code must retain the above copyright 10.\" notice, this list of conditions and the following disclaimer. 11.\" 2. Redistributions in binary form must reproduce the above copyright 12.\" notice, this list of conditions and the following disclaimer in the 13.\" documentation and/or other materials provided with the distribution. 14.\" 15.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25.\" SUCH DAMAGE. 26.\" 27.\" $FreeBSD: head/share/man/man9/ieee80211_input.9 233648 2012-03-29 05:02:12Z eadler $ 28.\" 29.Dd April 28, 2010 30.Dt IEEE80211_INPUT 9 31.Os 32.Sh NAME 33.Nm ieee80211_input 34.Nd software 802.11 stack input functions 35.Sh SYNOPSIS 36.In net/if.h 37.In net/if_media.h 38.In netproto/802_11/ieee80211_var.h 39.Ft void 40.Fo ieee80211_input 41.Fa "struct ieee80211_node *" 42.Fa "struct mbuf *" 43.Fa "int rssi" 44.Fa "int noise" 45.Fc 46.Ft void 47.Fo ieee80211_input_all 48.Fa "struct ieee80211com *" 49.Fa "struct mbuf *" 50.Fa "int rssi" 51.Fa "int noise" 52.Fc 53.Sh DESCRIPTION 54The 55.Nm net80211 56layer that supports 802.11 device drivers requires that 57receive processing be single-threaded. 58Typically this is done using a dedicated driver 59.Xr taskqueue 9 60thread. 61.Fn ieee80211_input 62and 63.Fn ieee80211_input_all 64process received 802.11 frames and are designed 65for use in that context; e.g. no driver locks may be held. 66.Pp 67The frame passed up in the 68.Vt mbuf 69must have the 802.11 protocol header at the front; all device-specific 70information and/or PLCP must be removed. 71Any CRC must be stripped from the end of the frame. 72The 802.11 protocol header should be 32-bit aligned for 73optimal performance but receive processing does not require it. 74If the frame holds a payload and that is not aligned to a 32-bit 75boundary then the payload will be re-aligned so that it is suitable 76for processing by protocols such as 77.Xr ip 4 . 78.Pp 79If a device (such as 80.Xr ath 4 ) 81inserts padding after the 802.11 header to align 82the payload to a 32-bit boundary the 83.Dv IEEE80211_C_DATAPAD 84capability must be set. 85Otherwise header and payload are assumed contiguous in the mbuf chain. 86.Pp 87If a received frame must pass 88through the A-MPDU receive reorder buffer then the mbuf 89must be marked with the 90.Dv M_AMPDU 91flag. 92Note that for the moment this is required of all frames received from 93a station and TID where a Block ACK stream is active, not just A-MPDU 94aggregates. 95It is sufficient to check for 96.Dv IEEE80211_NODE_HT 97in the 98.Vt ni_flags 99of the station's node table entry, any frames that do not require reorder 100processing will be dispatched with only minimal overhead. 101.Pp 102The 103.Vt rssi 104parameter is the Receive Signal Strength Indication of the frame 105measured in 0.5dBm units relative to the noise floor. 106The 107.Vt noise 108parameter is the best approximation of the noise floor in 109dBm units at the time the frame was received. 110RSSI and noise are used by the 111.Nm net80211 112layer to make scanning and roaming decisions in station mode 113and to do auto channel selection for hostap and similar modes. 114Otherwise the values are made available to user applications 115(with the rssi presented as a filtered average over the last ten values 116and the noise floor the last reported value). 117.Sh SEE ALSO 118.Xr ieee80211 9 119