nix-files/pkgs/additional/sane-scripts/src/sane-ip-reconnect

#!/usr/bin/env nix-shell
#!nix-shell -i python3 -p "python3.withPackages (ps: [ ])"
 
import re
import subprocess
import time
 
def rm_color(stdout: str) -> str:
" remove terminal control codes -- used by iwctl to colorize the output "
return re.sub("\\[[0-9;]*m", "", stdout)
 
def rm_heading(stdout: str) -> str:
return "\n".join(stdout.split("\n")[4:])
 
def extract_columns(stdout: str) -> list:
" split each line into two fields "
lines = stdout.split("\n")
items = []
for l in lines:
# XXX: this will fail for non-psk networks
# but i don't split on space because that would fail for networks that have names with spaces
if " psk " not in l: continue
split_at = l.find(" psk ")
first, second = l[:split_at], l[split_at+5:]
first, second = first.strip(), second.strip()
if first.startswith('> '):
# the `>` is formatting, indicating that it's the active network
first = first[2:].strip()
items.append((first, second))
return items
 
def iwctl(args: list, sudo: bool = False) -> str:
cmd = [ "iwctl" ] + args
if sudo:
cmd = [ "sudo" ] + cmd
res = subprocess.run(cmd, capture_output=True)
if res.returncode != 0:
print(f"iwctl failed:\n{res.stderr}")
res.check_returncode() # raise
return res.stdout.decode()
 
def scan():
iwctl(["station", "wlan0", "scan"], sudo=True)
time.sleep(5) # give time for adapter to see networks
 
def get_known() -> list:
stdout = iwctl(["known-networks", "list"])
stdout = rm_color(stdout)
stdout = rm_heading(stdout)
return [name for (name, date) in extract_columns(stdout)]
 
def get_visible() -> list:
stdout = iwctl(["station", "wlan0", "get-networks", "rssi-dbms"])
stdout = rm_color(stdout)
stdout = rm_heading(stdout)
return [(name, int(strength)) for (name, strength) in extract_columns(stdout)]
 
def choose_best(visible: list, known: list) -> str:
candidates = [(name, strength) for (name, strength) in visible if name in known]
# the least-negative RSSI is the best
return max(candidates, key=lambda c: c[1])[0]
 
def connect(network: str) -> str:
return iwctl(["station", "wlan0", "connect", network], sudo=True)
 
def restart() -> str:
return subprocess.check_output([
"sudo",
"systemctl",
"restart",
"iwd",
])
 
print("scanning for networks... ", end="", flush=True)
scan()
print("done")
print()
 
known = get_known()
print("known networks:", "".join(f"\n\t{name}" for name in known))
print()
 
visible = get_visible()
print("visible networks:", "".join(f"\n\t{name}: {rss}" for (name, rss) in visible))
print()
 
best = choose_best(visible, known)
 
try:
print(f"connecting to {best}")
result = connect(best)
except subprocess.CalledProcessError as e:
print("restarting iwd daemon")
restart()
else:
print("success", result)