2 * WPA Supplicant - Helper functions for scan result processing
3 * Copyright (c) 2007-2008, Jouni Malinen <j@w1.fi>
5 * This program is free software; you can redistribute it and/or modify
6 * it under the terms of the GNU General Public License version 2 as
7 * published by the Free Software Foundation.
9 * Alternatively, this software may be distributed under the terms of BSD
12 * See README and COPYING for more details.
18 #include "drivers/driver.h"
19 #include "ieee802_11_defs.h"
22 const u8 * wpa_scan_get_ie(const struct wpa_scan_res *res, u8 ie)
26 pos = (const u8 *) (res + 1);
27 end = pos + res->ie_len;
29 while (pos + 1 < end) {
30 if (pos + 2 + pos[1] > end)
41 const u8 * wpa_scan_get_vendor_ie(const struct wpa_scan_res *res,
46 pos = (const u8 *) (res + 1);
47 end = pos + res->ie_len;
49 while (pos + 1 < end) {
50 if (pos + 2 + pos[1] > end)
52 if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
53 vendor_type == WPA_GET_BE32(&pos[2]))
62 struct wpabuf * wpa_scan_get_vendor_ie_multi(const struct wpa_scan_res *res,
68 buf = wpabuf_alloc(res->ie_len);
72 pos = (const u8 *) (res + 1);
73 end = pos + res->ie_len;
75 while (pos + 1 < end) {
76 if (pos + 2 + pos[1] > end)
78 if (pos[0] == WLAN_EID_VENDOR_SPECIFIC && pos[1] >= 4 &&
79 vendor_type == WPA_GET_BE32(&pos[2]))
80 wpabuf_put_data(buf, pos + 2 + 4, pos[1] - 4);
84 if (wpabuf_len(buf) == 0) {
93 int wpa_scan_get_max_rate(const struct wpa_scan_res *res)
99 ie = wpa_scan_get_ie(res, WLAN_EID_SUPP_RATES);
100 for (i = 0; ie && i < ie[1]; i++) {
101 if ((ie[i + 2] & 0x7f) > rate)
102 rate = ie[i + 2] & 0x7f;
105 ie = wpa_scan_get_ie(res, WLAN_EID_EXT_SUPP_RATES);
106 for (i = 0; ie && i < ie[1]; i++) {
107 if ((ie[i + 2] & 0x7f) > rate)
108 rate = ie[i + 2] & 0x7f;
115 void wpa_scan_results_free(struct wpa_scan_results *res)
122 for (i = 0; i < res->num; i++)
123 os_free(res->res[i]);
129 /* Compare function for sorting scan results. Return >0 if @b is considered
131 static int wpa_scan_result_compar(const void *a, const void *b)
133 struct wpa_scan_res **_wa = (void *) a;
134 struct wpa_scan_res **_wb = (void *) b;
135 struct wpa_scan_res *wa = *_wa;
136 struct wpa_scan_res *wb = *_wb;
137 int wpa_a, wpa_b, maxrate_a, maxrate_b;
139 /* WPA/WPA2 support preferred */
140 wpa_a = wpa_scan_get_vendor_ie(wa, WPA_IE_VENDOR_TYPE) != NULL ||
141 wpa_scan_get_ie(wa, WLAN_EID_RSN) != NULL;
142 wpa_b = wpa_scan_get_vendor_ie(wb, WPA_IE_VENDOR_TYPE) != NULL ||
143 wpa_scan_get_ie(wb, WLAN_EID_RSN) != NULL;
150 /* privacy support preferred */
151 if ((wa->caps & IEEE80211_CAP_PRIVACY) == 0 &&
152 (wb->caps & IEEE80211_CAP_PRIVACY))
154 if ((wa->caps & IEEE80211_CAP_PRIVACY) &&
155 (wb->caps & IEEE80211_CAP_PRIVACY) == 0)
158 /* best/max rate preferred if signal level close enough XXX */
159 if ((wa->level && wb->level && abs(wb->level - wa->level) < 5) ||
160 (wa->qual && wb->qual && abs(wb->qual - wa->qual) < 10)) {
161 maxrate_a = wpa_scan_get_max_rate(wa);
162 maxrate_b = wpa_scan_get_max_rate(wb);
163 if (maxrate_a != maxrate_b)
164 return maxrate_b - maxrate_a;
167 /* use freq for channel preference */
169 /* all things being equal, use signal level; if signal levels are
170 * identical, use quality values since some drivers may only report
171 * that value and leave the signal level zero */
172 if (wb->level == wa->level)
173 return wb->qual - wa->qual;
174 return wb->level - wa->level;
178 void wpa_scan_sort_results(struct wpa_scan_results *res)
180 qsort(res->res, res->num, sizeof(struct wpa_scan_res *),
181 wpa_scan_result_compar);