From eba5f5c1e5a61ef65a970c699b9f93aff87448bf Mon Sep 17 00:00:00 2001
From: rnhmjoj <rnhmjoj@inventati.org>
Date: Mon, 7 Jun 2021 15:55:58 +0200
Subject: [PATCH 1/2] Revert "nixos/wireless: make wireless.interfaces
 mandatory"

This reverts commit 030a521adc9510207dd9f06b8d8b552ff7d999f9.
---
 nixos/doc/manual/release-notes/rl-2105.xml    |  9 -------
 .../services/networking/wpa_supplicant.nix    | 27 ++++++++++++-------
 2 files changed, 17 insertions(+), 19 deletions(-)

diff --git a/nixos/doc/manual/release-notes/rl-2105.xml b/nixos/doc/manual/release-notes/rl-2105.xml
index bdc2386f24c..54abbb6e38e 100644
--- a/nixos/doc/manual/release-notes/rl-2105.xml
+++ b/nixos/doc/manual/release-notes/rl-2105.xml
@@ -181,15 +181,6 @@
     <para>GNOME desktop environment was upgraded to 40, see the release notes for <link xlink:href="https://help.gnome.org/misc/release-notes/40.0/">40.0</link> and <link xlink:href="https://help.gnome.org/misc/release-notes/3.38/">3.38</link>. The <code>gnome3</code> attribute set has been renamed to <code>gnome</code> and so have been the NixOS options.</para>
    </listitem>
 
-   <listitem>
-    <para>
-     Enabling wireless networking now requires specifying at least one network
-     interface using <xref linkend="opt-networking.wireless.interfaces"/>.
-     This is to avoid a race condition with the card initialisation (see
-     <link xlink:href="https://github.com/NixOS/nixpkgs/issues/101963">issue
-     #101963</link> for more information).
-    </para>
-   </listitem>
    <listitem>
     <para>
      If you are using <option>services.udev.extraRules</option> to assign
diff --git a/nixos/modules/services/networking/wpa_supplicant.nix b/nixos/modules/services/networking/wpa_supplicant.nix
index d9308b37064..8a0685c3d96 100644
--- a/nixos/modules/services/networking/wpa_supplicant.nix
+++ b/nixos/modules/services/networking/wpa_supplicant.nix
@@ -40,7 +40,8 @@ in {
         default = [];
         example = [ "wlan0" "wlan1" ];
         description = ''
-          The interfaces <command>wpa_supplicant</command> will use.
+          The interfaces <command>wpa_supplicant</command> will use. If empty, it will
+          automatically use all wireless interfaces.
         '';
       };
 
@@ -219,14 +220,7 @@ in {
   };
 
   config = mkIf cfg.enable {
-    assertions = [
-      { assertion = cfg.interfaces != [];
-        message = ''
-          No network interfaces for wpa_supplicant have been configured.
-          Please, specify at least one using networking.wireless.interfaces.
-        '';
-      }
-    ] ++ flip mapAttrsToList cfg.networks (name: cfg: {
+    assertions = flip mapAttrsToList cfg.networks (name: cfg: {
       assertion = with cfg; count (x: x != null) [ psk pskRaw auth ] <= 1;
       message = ''options networking.wireless."${name}".{psk,pskRaw,auth} are mutually exclusive'';
     });
@@ -261,7 +255,20 @@ in {
         then echo >&2 "<3>/etc/wpa_supplicant.conf present but ignored. Generated ${configFile} is used instead."
         fi
         iface_args="-s -u -D${cfg.driver} ${configStr}"
-        args="${concatMapStringsSep " -N " (i: "-i${i} $iface_args") ifaces}"
+        ${if ifaces == [] then ''
+          for i in $(cd /sys/class/net && echo *); do
+            DEVTYPE=
+            UEVENT_PATH=/sys/class/net/$i/uevent
+            if [ -e "$UEVENT_PATH" ]; then
+              source "$UEVENT_PATH"
+              if [ "$DEVTYPE" = "wlan" -o -e /sys/class/net/$i/wireless ]; then
+                args+="''${args:+ -N} -i$i $iface_args"
+              fi
+            fi
+          done
+        '' else ''
+          args="${concatMapStringsSep " -N " (i: "-i${i} $iface_args") ifaces}"
+        ''}
         exec wpa_supplicant $args
       '';
     };

From be01320a6c39867eac0a20b4dfe04680d3b1ce26 Mon Sep 17 00:00:00 2001
From: rnhmjoj <rnhmjoj@inventati.org>
Date: Mon, 7 Jun 2021 16:01:52 +0200
Subject: [PATCH 2/2] nixos/wireless: only warn for no interfaces

A hard failure breaks the NixOS installer, which can't possibly
know the interface names in advance.
---
 .../modules/services/networking/wpa_supplicant.nix  | 13 +++++++++++++
 1 file changed, 13 insertions(+)

diff --git a/nixos/modules/services/networking/wpa_supplicant.nix b/nixos/modules/services/networking/wpa_supplicant.nix
index 8a0685c3d96..c0a4ce40760 100644
--- a/nixos/modules/services/networking/wpa_supplicant.nix
+++ b/nixos/modules/services/networking/wpa_supplicant.nix
@@ -42,6 +42,11 @@ in {
         description = ''
           The interfaces <command>wpa_supplicant</command> will use. If empty, it will
           automatically use all wireless interfaces.
+          <warning><para>
+            The automatic discovery of interfaces does not work reliably on boot:
+            it may fail and leave the system without network. When possible, specify
+            a known interface name.
+          </para></warning>
         '';
       };
 
@@ -225,6 +230,14 @@ in {
       message = ''options networking.wireless."${name}".{psk,pskRaw,auth} are mutually exclusive'';
     });
 
+    warnings =
+      optional (cfg.interfaces == [] && config.systemd.services.wpa_supplicant.wantedBy != [])
+      ''
+        No network interfaces for wpa_supplicant have been configured: the service
+        may randomly fail to start at boot. You should specify at least one using the option
+        networking.wireless.interfaces.
+      '';
+
     environment.systemPackages = [ package ];
 
     services.dbus.packages = [ package ];