From 2f195639ec9a568d0758c41d39f3358d3efbcbbf Mon Sep 17 00:00:00 2001 From: "Kanchanapally, Vidyullatha" Date: Thu, 21 Apr 2016 16:59:56 +0530 Subject: [PATCH] WNM: Fetch scan results before checking transition candidates On receiving a WNM BSS Transition Management Request frame with a candidate list, fetch the latest scan results from the kernel to see if there are any recent scan results for the candidates and initiate a connection if found. This helps to avoid triggering a new scan in cases where a scan initiated by something else (e.g., an internal beacon measurement report functionality in a driver) has processed Beacon or Probe Response frames without wpa_supplicant having received a notification of such an update yet. Signed-off-by: Jouni Malinen --- wpa_supplicant/scan.c | 10 +-- wpa_supplicant/scan.h | 5 ++ wpa_supplicant/wnm_sta.c | 162 ++++++++++++++++++++++++++++++++++----- 3 files changed, 151 insertions(+), 26 deletions(-) diff --git a/wpa_supplicant/scan.c b/wpa_supplicant/scan.c index b2576e376..8dab4426b 100644 --- a/wpa_supplicant/scan.c +++ b/wpa_supplicant/scan.c @@ -1875,8 +1875,8 @@ int wpa_supplicant_filter_bssid_match(struct wpa_supplicant *wpa_s, } -static void filter_scan_res(struct wpa_supplicant *wpa_s, - struct wpa_scan_results *res) +void filter_scan_res(struct wpa_supplicant *wpa_s, + struct wpa_scan_results *res) { size_t i, j; @@ -1909,7 +1909,7 @@ static void filter_scan_res(struct wpa_supplicant *wpa_s, #define DEFAULT_NOISE_FLOOR_2GHZ (-89) #define DEFAULT_NOISE_FLOOR_5GHZ (-92) -static void scan_snr(struct wpa_scan_res *res) +void scan_snr(struct wpa_scan_res *res) { if (res->flags & WPA_SCAN_NOISE_INVALID) { res->noise = IS_5GHZ(res->freq) ? @@ -1993,8 +1993,8 @@ static unsigned int max_vht80_rate(int snr) } -static void scan_est_throughput(struct wpa_supplicant *wpa_s, - struct wpa_scan_res *res) +void scan_est_throughput(struct wpa_supplicant *wpa_s, + struct wpa_scan_res *res) { enum local_hw_capab capab = wpa_s->hw_capab; int rate; /* max legacy rate in 500 kb/s units */ diff --git a/wpa_supplicant/scan.h b/wpa_supplicant/scan.h index ad9a23ef7..9f8d04e76 100644 --- a/wpa_supplicant/scan.h +++ b/wpa_supplicant/scan.h @@ -51,5 +51,10 @@ int wpas_mac_addr_rand_scan_set(struct wpa_supplicant *wpa_s, unsigned int type, const u8 *addr, const u8 *mask); int wpas_abort_ongoing_scan(struct wpa_supplicant *wpa_s); +void filter_scan_res(struct wpa_supplicant *wpa_s, + struct wpa_scan_results *res); +void scan_snr(struct wpa_scan_res *res); +void scan_est_throughput(struct wpa_supplicant *wpa_s, + struct wpa_scan_res *res); #endif /* SCAN_H */ diff --git a/wpa_supplicant/wnm_sta.c b/wpa_supplicant/wnm_sta.c index f77d51ae5..520b0095e 100644 --- a/wpa_supplicant/wnm_sta.c +++ b/wpa_supplicant/wnm_sta.c @@ -24,6 +24,7 @@ #define MAX_TFS_IE_LEN 1024 #define WNM_MAX_NEIGHBOR_REPORT 10 +#define WNM_SCAN_RESULT_AGE 2 /* 2 seconds */ /* get the TFS IE from driver */ static int ieee80211_11_get_tfs_ie(struct wpa_supplicant *wpa_s, u8 *buf, @@ -499,7 +500,7 @@ static void wnm_parse_neighbor_report(struct wpa_supplicant *wpa_s, static struct wpa_bss * -compare_scan_neighbor_results(struct wpa_supplicant *wpa_s) +compare_scan_neighbor_results(struct wpa_supplicant *wpa_s, os_time_t age_secs) { u8 i; @@ -532,6 +533,19 @@ compare_scan_neighbor_results(struct wpa_supplicant *wpa_s) continue; } + if (age_secs) { + struct os_reltime now; + + if (os_get_reltime(&now) == 0 && + os_reltime_expired(&now, &target->last_update, + age_secs)) { + wpa_printf(MSG_DEBUG, + "Candidate BSS is more than %ld seconds old", + age_secs); + continue; + } + } + if (bss->ssid_len != target->ssid_len || os_memcmp(bss->ssid, target->ssid, bss->ssid_len) != 0) { /* @@ -832,6 +846,41 @@ static void wnm_send_bss_transition_mgmt_resp( } +static void wnm_bss_tm_connect(struct wpa_supplicant *wpa_s, + struct wpa_bss *bss, struct wpa_ssid *ssid, + int after_new_scan) +{ + wpa_dbg(wpa_s, MSG_DEBUG, + "WNM: Transition to BSS " MACSTR + " based on BSS Transition Management Request (old BSSID " + MACSTR " after_new_scan=%d)", + MAC2STR(bss->bssid), MAC2STR(wpa_s->bssid), after_new_scan); + + /* Send the BSS Management Response - Accept */ + if (wpa_s->wnm_reply) { + wpa_s->wnm_reply = 0; + wpa_printf(MSG_DEBUG, + "WNM: Sending successful BSS Transition Management Response"); + wnm_send_bss_transition_mgmt_resp(wpa_s, + wpa_s->wnm_dialog_token, + WNM_BSS_TM_ACCEPT, + 0, bss->bssid); + } + + if (bss == wpa_s->current_bss) { + wpa_printf(MSG_DEBUG, + "WNM: Already associated with the preferred candidate"); + wnm_deallocate_memory(wpa_s); + return; + } + + wpa_s->reassociate = 1; + wpa_printf(MSG_DEBUG, "WNM: Issuing connect"); + wpa_supplicant_connect(wpa_s, bss, ssid); + wnm_deallocate_memory(wpa_s); +} + + int wnm_scan_process(struct wpa_supplicant *wpa_s, int reply_on_fail) { struct wpa_bss *bss; @@ -841,6 +890,8 @@ int wnm_scan_process(struct wpa_supplicant *wpa_s, int reply_on_fail) if (!wpa_s->wnm_neighbor_report_elements) return 0; + wpa_dbg(wpa_s, MSG_DEBUG, + "WNM: Process scan results for BSS Transition Management"); if (os_reltime_before(&wpa_s->wnm_cand_valid_until, &wpa_s->scan_trigger_time)) { wpa_printf(MSG_DEBUG, "WNM: Previously stored BSS transition candidate list is not valid anymore - drop it"); @@ -856,7 +907,7 @@ int wnm_scan_process(struct wpa_supplicant *wpa_s, int reply_on_fail) } /* Compare the Neighbor Report and scan results */ - bss = compare_scan_neighbor_results(wpa_s); + bss = compare_scan_neighbor_results(wpa_s, 0); if (!bss) { wpa_printf(MSG_DEBUG, "WNM: No BSS transition candidate match found"); status = WNM_BSS_TM_REJECT_NO_SUITABLE_CANDIDATES; @@ -864,25 +915,7 @@ int wnm_scan_process(struct wpa_supplicant *wpa_s, int reply_on_fail) } /* Associate to the network */ - /* Send the BSS Management Response - Accept */ - if (wpa_s->wnm_reply) { - wpa_s->wnm_reply = 0; - wnm_send_bss_transition_mgmt_resp(wpa_s, - wpa_s->wnm_dialog_token, - WNM_BSS_TM_ACCEPT, - 0, bss->bssid); - } - - if (bss == wpa_s->current_bss) { - wpa_printf(MSG_DEBUG, - "WNM: Already associated with the preferred candidate"); - wnm_deallocate_memory(wpa_s); - return 1; - } - - wpa_s->reassociate = 1; - wpa_supplicant_connect(wpa_s, bss, ssid); - wnm_deallocate_memory(wpa_s); + wnm_bss_tm_connect(wpa_s, bss, ssid, 1); return 1; send_bss_resp_fail: @@ -1023,6 +1056,79 @@ static void wnm_set_scan_freqs(struct wpa_supplicant *wpa_s) } +static int wnm_fetch_scan_results(struct wpa_supplicant *wpa_s) +{ + struct wpa_scan_results *scan_res; + struct wpa_bss *bss; + struct wpa_ssid *ssid = wpa_s->current_ssid; + u8 i, found = 0; + size_t j; + + wpa_dbg(wpa_s, MSG_DEBUG, + "WNM: Fetch current scan results from the driver for checking transition candidates"); + scan_res = wpa_drv_get_scan_results2(wpa_s); + if (!scan_res) { + wpa_dbg(wpa_s, MSG_DEBUG, "WNM: Failed to get scan results"); + return 0; + } + + if (scan_res->fetch_time.sec == 0) + os_get_reltime(&scan_res->fetch_time); + + filter_scan_res(wpa_s, scan_res); + + for (i = 0; i < wpa_s->wnm_num_neighbor_report; i++) { + struct neighbor_report *nei; + + nei = &wpa_s->wnm_neighbor_report_elements[i]; + if (nei->preference_present && nei->preference == 0) + continue; + + for (j = 0; j < scan_res->num; j++) { + struct wpa_scan_res *res; + const u8 *ssid_ie; + + res = scan_res->res[j]; + if (os_memcmp(nei->bssid, res->bssid, ETH_ALEN) != 0 || + res->age > WNM_SCAN_RESULT_AGE * 1000) + continue; + bss = wpa_s->current_bss; + ssid_ie = wpa_scan_get_ie(res, WLAN_EID_SSID); + if (bss && ssid_ie && + (bss->ssid_len != ssid_ie[1] || + os_memcmp(bss->ssid, ssid_ie + 2, + bss->ssid_len) != 0)) + continue; + + /* Potential candidate found */ + found = 1; + scan_snr(res); + scan_est_throughput(wpa_s, res); + wpa_bss_update_scan_res(wpa_s, res, + &scan_res->fetch_time); + } + } + + wpa_scan_results_free(scan_res); + if (!found) { + wpa_dbg(wpa_s, MSG_DEBUG, + "WNM: No transition candidate matches existing scan results"); + return 0; + } + + bss = compare_scan_neighbor_results(wpa_s, WNM_SCAN_RESULT_AGE); + if (!bss) { + wpa_dbg(wpa_s, MSG_DEBUG, + "WNM: Comparison of scan results against transition candidates did not find matches"); + return 0; + } + + /* Associate to the network */ + wnm_bss_tm_connect(wpa_s, bss, ssid, 0); + return 1; +} + + static void ieee802_11_rx_bss_trans_mgmt_req(struct wpa_supplicant *wpa_s, const u8 *pos, const u8 *end, int reply) @@ -1155,6 +1261,20 @@ static void ieee802_11_rx_bss_trans_mgmt_req(struct wpa_supplicant *wpa_s, wpa_s->wnm_cand_valid_until.usec %= 1000000; os_memcpy(wpa_s->wnm_cand_from_bss, wpa_s->bssid, ETH_ALEN); + /* + * Fetch the latest scan results from the kernel and check for + * candidates based on those results first. This can help in + * finding more up-to-date information should the driver has + * done some internal scanning operations after the last scan + * result update in wpa_supplicant. + */ + if (wnm_fetch_scan_results(wpa_s) > 0) + return; + + /* + * Try to use previously received scan results, if they are + * recent enough to use for a connection. + */ if (wpa_s->last_scan_res_used > 0) { struct os_reltime now;