From 9f06f893b40862fb75672bf185daaa90f3c43881 Mon Sep 17 00:00:00 2001
From: Timo Wilken
Date: Fri, 13 Oct 2023 15:10:50 +0200
Subject: Set WiFi regulatory domain on connection

---
 tw/system/lap.scm | 31 ++++++++++++++++++++++---------
 1 file changed, 22 insertions(+), 9 deletions(-)

diff --git a/tw/system/lap.scm b/tw/system/lap.scm
index 2a9a10ed..516de321 100644
--- a/tw/system/lap.scm
+++ b/tw/system/lap.scm
@@ -24,7 +24,7 @@
   #:use-module (tw services wireguard)
   #:use-module (tw system))
 
-(use-package-modules android certs cups disk docker file-systems gnome
+(use-package-modules android certs cups disk docker file-systems gnome guile
                      kerberos linux mtools pulseaudio search shells tls wm xorg)
 
 (use-service-modules admin authentication avahi base cups dbus desktop docker
@@ -85,24 +85,37 @@ EndSection
 (define set-timezone-script
   ;; Every time we connect to a network, get our timezone from network geolocation.
   ;; https://wiki.archlinux.org/title/System_time
-  (with-extensions (list guile-gnutls)  ; needed by (web client)
+  ;; https://wiki.archlinux.org/title/Network_configuration/Wireless#Respecting_the_regulatory_domain
+  (with-extensions (list guile-json-4 guile-gnutls)  ; guile-gnutls needed by (web client)
     #~(begin
-        (use-modules (srfi srfi-11)  ; `let-values'
+        (use-modules ((srfi srfi-11) #:select (let-values))
+                     (json)
                      (web client)
                      (web response))
-        (define tz-api-url "https://ipapi.co/timezone")
+        (define api-url "https://ipapi.co/json")
         ;; According to the Arch Wiki, when checking for "up" as the second
         ;; argument, VPN connections could cause undesired timezone changes.
         (when (and (string=? "connectivity-change" (caddr (command-line)))
                    (string=? "FULL" (getenv "CONNECTIVITY_STATE")))
-          (let-values (((response timezone) (http-get tz-api-url)))
+          (let-values (((response text) (http-get api-url)))
             (unless (= 200 (response-code response))
               (error "Got error response to request:" response))
-            (let ((zonefile (string-append #$tzdata "/share/zoneinfo/" timezone)))
+            (let* ((json (json-string->scm text))
+                   (timezone (assoc-ref json "timezone"))
+                   (zonefile (string-append #$tzdata "/share/zoneinfo/" timezone))
+                   (regdb-country (assoc-ref json "country_code"))
+                   (error-code
+                    (status:exit-val
+                     ;; Set WiFi regulatory domain to use the correct channels.
+                     (system* #$(file-append iw "/bin/iw") "reg" "set" regdb-country))))
+              (format (current-error-port) "Updated WiFi regdomain to ~a: ~a~%"
+                      regdb-country (if (zero? error-code) "success"
+                                        (format #f "error ~d" error-code)))
+              ;; Set local timezone.
               (delete-file "/etc/localtime")
-              (symlink zonefile "/etc/localtime"))
-            (format (current-error-port)
-                    "Successfully updated timezone to ~a~%" timezone))))))
+              (symlink zonefile "/etc/localtime")
+              (format (current-error-port)
+                      "Updated timezone to ~a: success~%" timezone)))))))
 
 (define-public %lap-system
   (operating-system
-- 
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