wifi: merge branch 'th/wifi-random-hotspot-channel'

https://gitlab.freedesktop.org/NetworkManager/NetworkManager/-/merge_requests/1099

6 files changed, 100 insertions, 30 deletions

diff --git a/NEWS b/NEWS
index fd150ea434..7b58fecf6e 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,9 @@ subject to change and not guaranteed to be compatible with
 the later release.
 USE AT YOUR OWN RISK.  NOT RECOMMENDED FOR PRODUCTION USE!
 
+* Wi-Fi hotspots will use a (stable) random channel number unless one is
+  chosen manually.
+
 =============================================
 NetworkManager-1.36
 Overview of changes since NetworkManager-1.34
diff --git a/src/core/devices/wifi/nm-device-wifi.c b/src/core/devices/wifi/nm-device-wifi.c
index cfb73848fb..314ba56688 100644
--- a/src/core/devices/wifi/nm-device-wifi.c
+++ b/src/core/devices/wifi/nm-device-wifi.c
@@ -3103,28 +3103,75 @@ act_stage1_prepare(NMDevice *device, NMDeviceStateReason *out_failure_reason)
 static void
 ensure_hotspot_frequency(NMDeviceWifi *self, NMSettingWireless *s_wifi, NMWifiAP *ap)
 {
-    NMDevice     *device     = NM_DEVICE(self);
-    const char   *band       = nm_setting_wireless_get_band(s_wifi);
-    const guint32 a_freqs[]  = {5180, 5200, 5220, 5745, 5765, 5785, 5805, 0};
-    const guint32 bg_freqs[] = {2412, 2437, 2462, 2472, 0};
-    guint32       freq       = 0;
-
-    g_assert(ap);
+    guint32     a_freqs[]  = {5180, 5200, 5220, 5745, 5765, 5785, 5805, 0};
+    guint32     bg_freqs[] = {2412, 2437, 2462, 2472, 0};
+    guint32    *rnd_freqs;
+    guint       rnd_freqs_len;
+    NMDevice   *device = NM_DEVICE(self);
+    const char *band   = nm_setting_wireless_get_band(s_wifi);
+    guint32     freq;
+    guint64     rnd;
+    guint       i;
+    guint       l;
+
+    nm_assert(ap);
+    nm_assert(NM_IN_STRSET(band, NULL, "a", "bg"));
 
     if (nm_wifi_ap_get_freq(ap))
         return;
 
-    if (g_strcmp0(band, "a") == 0)
-        freq = nm_platform_wifi_find_frequency(nm_device_get_platform(device),
-                                               nm_device_get_ifindex(device),
-                                               a_freqs);
-    else
-        freq = nm_platform_wifi_find_frequency(nm_device_get_platform(device),
-                                               nm_device_get_ifindex(device),
-                                               bg_freqs);
+    {
+        GBytes       *ssid;
+        gsize         ssid_len;
+        const guint8 *ssid_data;
+        const guint8  random_seed[16] = {0x9a,
+                                        0xdc,
+                                        0x86,
+                                        0x9a,
+                                        0xa8,
+                                        0xa2,
+                                        0x07,
+                                        0x97,
+                                        0xbe,
+                                        0x6d,
+                                        0xe6,
+                                        0x99,
+                                        0x9f,
+                                        0xa8,
+                                        0x09,
+                                        0x2b};
+
+        /* Calculate a stable "random" number based on the SSID. */
+        ssid      = nm_setting_wireless_get_ssid(s_wifi);
+        ssid_data = g_bytes_get_data(ssid, &ssid_len);
+        rnd       = c_siphash_hash(random_seed, ssid_data, ssid_len);
+    }
+
+    if (nm_streq0(band, "a")) {
+        rnd_freqs     = a_freqs;
+        rnd_freqs_len = G_N_ELEMENTS(a_freqs) - 1;
+    } else {
+        rnd_freqs     = bg_freqs;
+        rnd_freqs_len = G_N_ELEMENTS(bg_freqs) - 1;
+    }
+
+    /* shuffle the frequencies (inplace). The idea is to choose
+     * a different frequency depending on the SSID. */
+    for (i = 0, l = rnd_freqs_len; l > 1; i++, l--) {
+        /* Add an arbitrary chosen (prime) number to rnd, to get more "random"
+         * numbers. Since we only shuffle a handful of elements, that's good
+         * enough (and stable). */
+        rnd += 5630246189u;
+        NM_SWAP(&rnd_freqs[i], &rnd_freqs[i + (rnd % l)]);
+    }
+
+    freq = nm_platform_wifi_find_frequency(nm_device_get_platform(device),
+                                           nm_device_get_ifindex(device),
+                                           rnd_freqs);
+    if (freq == 0)
+        freq = rnd_freqs[0];
 
-    if (!freq)
-        freq = (g_strcmp0(band, "a") == 0) ? 5180 : 2462;
+    _LOGD(LOGD_WIFI, "set frequency for hotspot AP to %u", freq);
 
     if (nm_wifi_ap_set_freq(ap, freq))
         _ap_dump(self, LOGL_DEBUG, ap, "updated", 0);
diff --git a/src/libnm-platform/nm-linux-platform.c b/src/libnm-platform/nm-linux-platform.c
index ce21ebbb7a..f87182936a 100644
--- a/src/libnm-platform/nm-linux-platform.c
+++ b/src/libnm-platform/nm-linux-platform.c
@@ -8451,6 +8451,7 @@ static gboolean
 wifi_get_capabilities(NMPlatform *platform, int ifindex, _NMDeviceWifiCapabilities *caps)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, FALSE);
+
     if (caps)
         *caps = nm_wifi_utils_get_caps(wifi_data);
     return TRUE;
@@ -8460,6 +8461,7 @@ static guint32
 wifi_get_frequency(NMPlatform *platform, int ifindex)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, 0);
+
     return nm_wifi_utils_get_freq(wifi_data);
 }
 
@@ -8471,6 +8473,7 @@ wifi_get_station(NMPlatform  *platform,
                  guint32     *out_rate)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, FALSE);
+
     return nm_wifi_utils_get_station(wifi_data, out_bssid, out_quality, out_rate);
 }
 
@@ -8478,6 +8481,7 @@ static _NM80211Mode
 wifi_get_mode(NMPlatform *platform, int ifindex)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, _NM_802_11_MODE_UNKNOWN);
+
     return nm_wifi_utils_get_mode(wifi_data);
 }
 
@@ -8485,6 +8489,7 @@ static void
 wifi_set_mode(NMPlatform *platform, int ifindex, _NM80211Mode mode)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, );
+
     nm_wifi_utils_set_mode(wifi_data, mode);
 }
 
@@ -8492,6 +8497,7 @@ static void
 wifi_set_powersave(NMPlatform *platform, int ifindex, guint32 powersave)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, );
+
     nm_wifi_utils_set_powersave(wifi_data, powersave);
 }
 
@@ -8499,6 +8505,7 @@ static guint32
 wifi_find_frequency(NMPlatform *platform, int ifindex, const guint32 *freqs)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, 0);
+
     return nm_wifi_utils_find_freq(wifi_data, freqs);
 }
 
@@ -8506,6 +8513,7 @@ static void
 wifi_indicate_addressing_running(NMPlatform *platform, int ifindex, gboolean running)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, );
+
     nm_wifi_utils_indicate_addressing_running(wifi_data, running);
 }
 
@@ -8513,6 +8521,7 @@ static _NMSettingWirelessWakeOnWLan
 wifi_get_wake_on_wlan(NMPlatform *platform, int ifindex)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, FALSE);
+
     return nm_wifi_utils_get_wake_on_wlan(wifi_data);
 }
 
@@ -8520,6 +8529,7 @@ static gboolean
 wifi_set_wake_on_wlan(NMPlatform *platform, int ifindex, _NMSettingWirelessWakeOnWLan wowl)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, FALSE);
+
     return nm_wifi_utils_set_wake_on_wlan(wifi_data, wowl);
 }
 
@@ -8565,6 +8575,7 @@ static guint32
 mesh_get_channel(NMPlatform *platform, int ifindex)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, 0);
+
     return nm_wifi_utils_get_mesh_channel(wifi_data);
 }
 
@@ -8572,6 +8583,7 @@ static gboolean
 mesh_set_channel(NMPlatform *platform, int ifindex, guint32 channel)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, FALSE);
+
     return nm_wifi_utils_set_mesh_channel(wifi_data, channel);
 }
 
@@ -8579,6 +8591,7 @@ static gboolean
 mesh_set_ssid(NMPlatform *platform, int ifindex, const guint8 *ssid, gsize len)
 {
     WIFI_GET_WIFI_DATA_NETNS(wifi_data, platform, ifindex, FALSE);
+
     return nm_wifi_utils_set_mesh_ssid(wifi_data, ssid, len);
 }
 
diff --git a/src/libnm-platform/wifi/nm-wifi-utils-nl80211.c b/src/libnm-platform/wifi/nm-wifi-utils-nl80211.c
index 2fa46e3884..2659414e11 100644
--- a/src/libnm-platform/wifi/nm-wifi-utils-nl80211.c
+++ b/src/libnm-platform/wifi/nm-wifi-utils-nl80211.c
@@ -382,12 +382,14 @@ wifi_nl80211_find_freq(NMWifiUtils *data, const guint32 *freqs)
 {
     NMWifiUtilsNl80211 *self = (NMWifiUtilsNl80211 *) data;
     int                 i;
-
-    for (i = 0; i < self->num_freqs; i++) {
-        while (*freqs) {
-            if (self->freqs[i] == *freqs)
-                return *freqs;
-            freqs++;
+    int                 j;
+
+    /* It's important to check the values in the order of @freqs, because
+     * that array might be sorted to contain preferred frequencies first. */
+    for (j = 0; freqs[j] != 0; j++) {
+        for (i = 0; i < self->num_freqs; i++) {
+            if (self->freqs[i] == freqs[j])
+                return freqs[j];
         }
     }
     return 0;
diff --git a/src/libnm-platform/wifi/nm-wifi-utils-wext.c b/src/libnm-platform/wifi/nm-wifi-utils-wext.c
index 2d4112bc05..678d71fe60 100644
--- a/src/libnm-platform/wifi/nm-wifi-utils-wext.c
+++ b/src/libnm-platform/wifi/nm-wifi-utils-wext.c
@@ -252,13 +252,15 @@ static guint32
 wifi_wext_find_freq(NMWifiUtils *data, const guint32 *freqs)
 {
     NMWifiUtilsWext *wext = (NMWifiUtilsWext *) data;
-    int              i;
-
-    for (i = 0; i < wext->num_freqs; i++) {
-        while (*freqs) {
-            if (wext->freqs[i] == *freqs)
-                return *freqs;
-            freqs++;
+    guint            i;
+    guint            j;
+
+    /* It's important to check the values in the order of @freqs, because
+     * that array might be sorted to contain preferred frequencies first. */
+    for (j = 0; freqs[j] != 0; j++) {
+        for (i = 0; i < wext->num_freqs; i++) {
+            if (wext->freqs[i] == freqs[j])
+                return freqs[j];
         }
     }
     return 0;
diff --git a/src/libnm-platform/wifi/nm-wifi-utils.c b/src/libnm-platform/wifi/nm-wifi-utils.c
index 8bdd65c2bc..1e484cfd1b 100644
--- a/src/libnm-platform/wifi/nm-wifi-utils.c
+++ b/src/libnm-platform/wifi/nm-wifi-utils.c
@@ -60,6 +60,7 @@ _NM80211Mode
 nm_wifi_utils_get_mode(NMWifiUtils *data)
 {
     g_return_val_if_fail(data != NULL, _NM_802_11_MODE_UNKNOWN);
+
     return NM_WIFI_UTILS_GET_CLASS(data)->get_mode(data);
 }
 
@@ -118,6 +119,7 @@ guint32
 nm_wifi_utils_get_freq(NMWifiUtils *data)
 {
     g_return_val_if_fail(data != NULL, 0);
+
     return NM_WIFI_UTILS_GET_CLASS(data)->get_freq(data);
 }
 
@@ -126,6 +128,7 @@ nm_wifi_utils_find_freq(NMWifiUtils *data, const guint32 *freqs)
 {
     g_return_val_if_fail(data != NULL, 0);
     g_return_val_if_fail(freqs != NULL, 0);
+
     return NM_WIFI_UTILS_GET_CLASS(data)->find_freq(data, freqs);
 }