1<html><head><meta http-equiv="Content-Type" content="text/html; charset=ANSI_X3.4-1968"><title>Chapter 3. Scanning and BSS list handling</title><meta name="generator" content="DocBook XSL Stylesheets V1.78.1"><link rel="home" href="index.html" title="The 802.11 subsystems – for kernel developers"><link rel="up" href="cfg80211-developers-guide.html" title="The cfg80211 subsystem"><link rel="prev" href="API-cfg80211-michael-mic-failure.html" title="cfg80211_michael_mic_failure"><link rel="next" href="API-struct-cfg80211-ssid.html" title="struct cfg80211_ssid"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 3. Scanning and BSS list handling</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="API-cfg80211-michael-mic-failure.html">Prev</a> </td><th width="60%" align="center">The cfg80211 subsystem</th><td width="20%" align="right"> <a accesskey="n" href="API-struct-cfg80211-ssid.html">Next</a></td></tr></table><hr></div><div class="chapter"><div class="titlepage"><div><div><h1 class="title"><a name="idp1112952044"></a>Chapter 3. Scanning and BSS list handling</h1></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl class="toc"><dt><span class="refentrytitle"><a href="API-struct-cfg80211-ssid.html"><span class="phrase">struct cfg80211_ssid</span></a></span><span class="refpurpose"> — 2 SSID description 3 </span></dt><dt><span class="refentrytitle"><a href="API-struct-cfg80211-scan-request.html"><span class="phrase">struct cfg80211_scan_request</span></a></span><span class="refpurpose"> — 4 scan request description 5 </span></dt><dt><span class="refentrytitle"><a href="API-cfg80211-scan-done.html"><span class="phrase">cfg80211_scan_done</span></a></span><span class="refpurpose"> — 6 notify that scan finished 7 </span></dt><dt><span class="refentrytitle"><a href="API-struct-cfg80211-bss.html"><span class="phrase">struct cfg80211_bss</span></a></span><span class="refpurpose"> — 8 BSS description 9 </span></dt><dt><span class="refentrytitle"><a href="API-cfg80211-inform-bss-width-frame.html"><span class="phrase">cfg80211_inform_bss_width_frame</span></a></span><span class="refpurpose"> — 10 inform cfg80211 of a received BSS frame 11 </span></dt><dt><span class="refentrytitle"><a href="API-cfg80211-inform-bss-width.html"><span class="phrase">cfg80211_inform_bss_width</span></a></span><span class="refpurpose"> — 12 inform cfg80211 of a new BSS 13 </span></dt><dt><span class="refentrytitle"><a href="API-cfg80211-unlink-bss.html"><span class="phrase">cfg80211_unlink_bss</span></a></span><span class="refpurpose"> — 14 unlink BSS from internal data structures 15 </span></dt><dt><span class="refentrytitle"><a href="API-cfg80211-find-ie.html"><span class="phrase">cfg80211_find_ie</span></a></span><span class="refpurpose"> — 16 find information element in data 17 </span></dt><dt><span class="refentrytitle"><a href="API-ieee80211-bss-get-ie.html"><span class="phrase">ieee80211_bss_get_ie</span></a></span><span class="refpurpose"> — 18 find IE with given ID 19 </span></dt></dl></div><p> 20 </p><p> 21 The scanning process itself is fairly simple, but cfg80211 offers quite 22 a bit of helper functionality. To start a scan, the scan operation will 23 be invoked with a scan definition. This scan definition contains the 24 channels to scan, and the SSIDs to send probe requests for (including the 25 wildcard, if desired). A passive scan is indicated by having no SSIDs to 26 probe. Additionally, a scan request may contain extra information elements 27 that should be added to the probe request. The IEs are guaranteed to be 28 well-formed, and will not exceed the maximum length the driver advertised 29 in the wiphy structure. 30 </p><p> 31 When scanning finds a BSS, cfg80211 needs to be notified of that, because 32 it is responsible for maintaining the BSS list; the driver should not 33 maintain a list itself. For this notification, various functions exist. 34 </p><p> 35 Since drivers do not maintain a BSS list, there are also a number of 36 functions to search for a BSS and obtain information about it from the 37 BSS structure cfg80211 maintains. The BSS list is also made available 38 to userspace. 39</p></div><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="API-cfg80211-michael-mic-failure.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="cfg80211-developers-guide.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="API-struct-cfg80211-ssid.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top"><span class="phrase">cfg80211_michael_mic_failure</span> </td><td width="20%" align="center"><a accesskey="h" href="index.html">Home</a></td><td width="40%" align="right" valign="top"> <span class="phrase">struct cfg80211_ssid</span></td></tr></table></div></body></html> 40