wpa_supplicant: Initial connection speedup

Add initial_freq_list to wpa_supplicant configuration. This option
allows wpa_supplicant to scan a smaller list of frequencies when it
starts. This in turn allows for a faster connection to an already known
network. This limit applies only for the initial scan operation and does
not restrict other channels from being used in consecutive scans.

Tests have shown this to reduce the amount of time for connecting to a
network from roughly 3 seconds to roughly 0.1 second.

Signed-off-by: Frederik Juul <frederik.juul@3shape.com>

diff --git a/wpa_supplicant/config.c b/wpa_supplicant/config.c
index c5161544db0dcf407de1bc9c8b554a9bc11c006c..0aa92a28c7f1ca3873f0f1d8201bcd47e00e06f6 100644 (file)
--- a/wpa_supplicant/config.c
+++ b/wpa_supplicant/config.c
@@ -2890,6 +2890,7 @@ void wpa_config_free(struct wpa_config *config)
        os_free(config->p2p_no_go_freq.range);
        os_free(config->autoscan);
        os_free(config->freq_list);
+       os_free(config->initial_freq_list);
        wpabuf_free(config->wps_nfc_dh_pubkey);
        wpabuf_free(config->wps_nfc_dh_privkey);
        wpabuf_free(config->wps_nfc_dev_pw);
@@ -4547,6 +4548,26 @@ static int wpa_config_process_freq_list(const struct global_parse_data *data,
 }
 
 
+static int
+wpa_config_process_initial_freq_list(const struct global_parse_data *data,
+                                    struct wpa_config *config, int line,
+                                    const char *value)
+{
+       int *freqs;
+
+       freqs = wpa_config_parse_int_array(value);
+       if (!freqs)
+               return -1;
+       if (freqs[0] == 0) {
+               os_free(freqs);
+               freqs = NULL;
+       }
+       os_free(config->initial_freq_list);
+       config->initial_freq_list = freqs;
+       return 0;
+}
+
+
 #ifdef CONFIG_P2P
 static int wpa_global_config_parse_ipv4(const struct global_parse_data *data,
                                        struct wpa_config *config, int line,
@@ -5082,6 +5103,7 @@ static const struct global_parse_data global_fields[] = {
        { FUNC(ap_vendor_elements), 0 },
        { INT_RANGE(ignore_old_scan_res, 0, 1), 0 },
        { FUNC(freq_list), 0 },
+       { FUNC(initial_freq_list), 0},
        { INT(scan_cur_freq), 0 },
        { INT(sched_scan_interval), 0 },
        { INT(sched_scan_start_delay), 0 },

diff --git a/wpa_supplicant/config.h b/wpa_supplicant/config.h
index 648573de05476c63cb23617a6e81192b6f1be566..d128cd9bf1db5e83db8cb866bbbb835f1f77acb2 100644 (file)
--- a/wpa_supplicant/config.h
+++ b/wpa_supplicant/config.h
@@ -916,6 +916,19 @@ struct wpa_config {
         */
        int *freq_list;
 
+       /**
+        * initial_freq_list - like freq_list but for initial scan
+        *
+        * This is an optional zero-terminated array of frequencies in
+        * megahertz (MHz) to allow for narrowing scanning range when
+        * the application is started.
+        *
+        * This can be used to speed up initial connection time if the
+        * channel is known ahead of time, without limiting the scanned
+        * frequencies during normal use.
+        */
+       int *initial_freq_list;
+
        /**
         * scan_cur_freq - Whether to scan only the current channel
         *

diff --git a/wpa_supplicant/config_file.c b/wpa_supplicant/config_file.c
index 246644a336b775cc62f0fe9527c65e7de2227ce6..cb04a78a21fc9eae805adaa1672d039fdb1a72e4 100644 (file)
--- a/wpa_supplicant/config_file.c
+++ b/wpa_supplicant/config_file.c
@@ -1475,6 +1475,15 @@ static void wpa_config_write_global(FILE *f, struct wpa_config *config)
                }
                fprintf(f, "\n");
        }
+       if (config->initial_freq_list && config->initial_freq_list[0]) {
+               int i;
+               fprintf(f, "initial_freq_list=");
+               for (i = 0; config->initial_freq_list[i]; i++) {
+                       fprintf(f, "%s%d", i > 0 ? " " : "",
+                               config->initial_freq_list[i]);
+               }
+               fprintf(f, "\n");
+       }
        if (config->scan_cur_freq != DEFAULT_SCAN_CUR_FREQ)
                fprintf(f, "scan_cur_freq=%d\n", config->scan_cur_freq);
 

diff --git a/wpa_supplicant/scan.c b/wpa_supplicant/scan.c
index 78371d3ad5d6373d269506ce7aa7105a382af0d6..9ac6581516fd8f0e6bb7ed18eb7df7c1f9f84458 100644 (file)
--- a/wpa_supplicant/scan.c
+++ b/wpa_supplicant/scan.c
@@ -1201,7 +1201,12 @@ ssid_list_set:
        wpa_setband_scan_freqs(wpa_s, &params);
 
        /* See if user specified frequencies. If so, scan only those. */
-       if (wpa_s->conf->freq_list && !params.freqs) {
+       if (wpa_s->last_scan_req == INITIAL_SCAN_REQ &&
+           wpa_s->conf->initial_freq_list && !params.freqs) {
+               wpa_dbg(wpa_s, MSG_DEBUG,
+                       "Optimize scan based on conf->initial_freq_list");
+               int_array_concat(&params.freqs, wpa_s->conf->initial_freq_list);
+       } else if (wpa_s->conf->freq_list && !params.freqs) {
                wpa_dbg(wpa_s, MSG_DEBUG,
                        "Optimize scan based on conf->freq_list");
                int_array_concat(&params.freqs, wpa_s->conf->freq_list);