firmware: Add ability to load config from USB

firmware/app.nix

@@ -5,8 +5,10 @@ let
     isExecutable = true;
 
     python = pkgs.python3.withPackages (ps: with ps; [ pyyaml ]);
+    utilLinux = pkgs.util-linux;
     wireguardTools = pkgs.wireguard-tools;
     systemd = config.systemd.package;
+    inherit (pkgs) iwd;
   };
 in
 {
@@ -18,14 +20,19 @@ in
           after = [ "network.target" ];
 
           serviceConfig = {
-            Type = "oneshot";
-            RemainAfterExit = true;
-            ExecStart = "${configurer}";
+            Type = "notify-reload";
+            ExecStart = "${configurer} serve";
           };
 
           wantedBy = [ "multi-user.target" ];
         };
       };
     };
+
+    services = {
+      udev.extraRules = ''
+        SUBSYSTEM=="block", ACTION=="add", ENV{ID_BUS}=="usb", ENV{ID_FS_TYPE}=="vfat", RUN+="${configurer} ext-load %E{ID_PATH_TAG} %N"
+      '';
+    };
   };
 }

firmware/configurer.py

@@ -1,11 +1,15 @@
 #! @python@/bin/python -B
+import argparse
 import base64
 import json
 import os
 import shutil
+import signal
 import socket
 import subprocess
 import sys
+import time
+import tomllib
 
 import yaml
 
@@ -37,18 +41,34 @@ def iwd_ssid_basename(ssid: str) -> str:
   return f"={ssid.encode('utf-8').hex()}"
 
 class Configurer:
-  tmpdir = '/tmp/qclk'
+  tmpdir = '/run/qclk'
 
   def __init__(self, conf_file: str, wg_key_file: str):
-    with open(conf_file) as f:
-      self.config = yaml.safe_load(f)
+    self.conf_file = conf_file
+    self.load_config()
 
     with open(wg_key_file, 'rb') as f:
       output = subprocess.check_output(['@wireguardTools@/bin/wg', 'pubkey'], input=f.read())
     pubkey = base64.b64decode(output)
     self.id = pubkey[:4].hex()
 
+    self.load_dir = os.path.join(self.tmpdir, 'load')
+    self.sd_sock = None
+
     os.makedirs(self.tmpdir, exist_ok=True)
+    os.makedirs(self.load_dir, exist_ok=True)
+
+  def load_config(self):
+    with open(self.conf_file) as f:
+      self.config = yaml.safe_load(f)
+
+  def write_config(self):
+    log(f'Updaing config')
+    tmp = os.path.join(self.tmpdir, 'new-config.yaml')
+    with open(tmp, 'w') as f:
+      yaml.dump(self.config, f)
+
+    shutil.move(tmp, self.conf_file)
 
   def _setup_hostname(self):
     hostname = f'qclk-{self.id}'
@@ -78,6 +98,8 @@ class Configurer:
         log(f"Cleaning up old IWD config '{f}'")
         os.remove(os.path.join(IWD_PATH, f))
 
+    subprocess.call(['@iwd@/bin/iwctl', 'station', 'wifi', 'scan'])
+
   def _setup_mgmt(self):
     conf = self.config['management']
     tmp = os.path.join(self.tmpdir, 'management.network')
@@ -90,13 +112,118 @@ class Configurer:
     subprocess.check_call(['@systemd@/bin/networkctl', 'reload'])
 
   def reconcile(self):
+    if self.sd_sock is not None:
+      self.sd_sock.sendall(b'STATUS=Reconciling configuration...')
+
     self._setup_hostname()
     self._setup_wifi()
     self._setup_mgmt()
 
+    if self.sd_sock is not None:
+      self.sd_sock.sendall(b'STATUS=OK\nREADY=1')
+
+  def _ext_load(self, identifier: str, device: str):
+    mountpoint = os.path.join(self.tmpdir, 'mnt', identifier)
+    os.makedirs(mountpoint, exist_ok=True)
+
+    try:
+      log(f'Mounting {device} -> {mountpoint}')
+      subprocess.check_call(['@utilLinux@/bin/mount', '-t', 'vfat', '-o', 'ro', device, mountpoint])
+      try:
+        path = os.path.join(mountpoint, 'qclk.toml')
+        if not os.path.exists(path):
+          log(f'No config file found on {device}')
+          return
+
+        with open(path, 'rb') as f:
+          ext_conf = tomllib.load(f)
+      finally:
+        subprocess.check_call(['@utilLinux@/bin/umount', mountpoint])
+    finally:
+      os.rmdir(mountpoint)
+
+    if 'wifi' in ext_conf:
+      log(f'Loading WiFi settings from {device}')
+      self.config['wifi'] = {
+        'ssid': ext_conf['wifi']['ssid'],
+        'password': ext_conf['wifi'].get('password', ''),
+        'hidden': ext_conf['wifi'].get('hidden', False),
+      }
+      self._setup_wifi()
+      self.write_config()
+
+  def serve(self, args: argparse.Namespace):
+    os.makedirs(os.path.join(self.tmpdir, 'load'), exist_ok=True)
+
+    addr = os.getenv('NOTIFY_SOCKET')
+    if addr is not None:
+      self.sd_sock = socket.socket(socket.AF_UNIX, socket.SOCK_DGRAM)
+      if addr[0] == '@':
+        addr = '\0' + addr[1:]
+      self.sd_sock.connect(addr)
+
+    running = True
+    def sighandler(sig, frame):
+      nonlocal running
+      if sig in (signal.SIGINT, signal.SIGTERM):
+        running = False
+        return
+
+      if sig == signal.SIGHUP:
+        if self.sd_sock is not None:
+          t = time.clock_gettime_ns(time.CLOCK_MONOTONIC) // 1000
+          self.sd_sock.sendall(f'RELOADING=1\nMONOTONIC_USEC={t}'.encode('ascii'))
+        self.load_config()
+        self.reconcile()
+      elif sig == signal.SIGUSR1:
+        for identifier in os.listdir(self.load_dir):
+          fname = os.path.join(self.load_dir, identifier)
+          with open(fname) as f:
+            device = f.read().strip()
+          os.remove(fname)
+
+          try:
+            self._ext_load(identifier, device)
+          except Exception as ex:
+            log(f'Failed to load config from {device}: {ex}')
+
+    for s in [signal.SIGINT, signal.SIGTERM, signal.SIGHUP, signal.SIGUSR1]:
+      signal.signal(s, sighandler)
+
+    self.reconcile()
+    while running:
+      signal.pause()
+
+    if self.sd_sock is not None:
+      self.sd_sock.close()
+
+  def ext_load(self, args: argparse.Namespace):
+    with open(os.path.join(self.load_dir, args.identifier), 'w') as f:
+      print(args.device, file=f)
+    output = subprocess.check_output(
+      ['@systemd@/bin/systemctl', 'show', '--property', 'MainPID', '--value', 'qclk-configurer.service'], encoding='ascii')
+    pid = int(output.strip())
+
+    os.kill(pid, signal.SIGUSR1)
+
 def main():
+  parser = argparse.ArgumentParser(description='qclkOS configurer')
+  cmds = parser.add_subparsers(title='commands', help='reconcile')
+
+  rec_parser = cmds.add_parser('serve')
+  rec_parser.set_defaults(func=Configurer.serve)
+
+  eload_parser = cmds.add_parser('ext-load')
+  eload_parser.set_defaults(func=Configurer.ext_load)
+  eload_parser.add_argument('identifier', help='Unique device name')
+  eload_parser.add_argument('device', help='Block device path')
+
+  args = parser.parse_args()
   c = Configurer(CONF_FILE, WG_KEY_FILE)
-  c.reconcile()
+  if not hasattr(args, 'func'):
+    c.serve(args)
+  else:
+    args.func(c, args)
 
 if __name__ == '__main__':
   main()