reconnect-wifi

#!/bin/bash

set -e -f -u -o pipefail

# Run this command to configure the network to keep trying if connecting to the
# network fails.
# $ dir="/System/Library/PrivateFrameworks/Apple80211.framework/Versions/A"
# $ sudo "${dir}/Resources/airport" \
#     prefs joinmode=Preferred joinmodefallback=KeepLooking
# Run "airport prefs" to check current preferences.

readonly ATTEMPTS="${1:-10}" SLEEP_TIME="${2:-20}"
readonly DRYRUN="no"
# Figure out which network interface is wifi from the output of
# networksetup -listnetworkserviceorder
readonly WIFI_DEV="en1"
readonly SSID="burrow"

readonly INTERNAL_IP="192.168.86.1"
readonly LOG_FILE="${HOME}/tmp/logs/reconnect-wifi.log"

log() {
  local now
  now="$(date)"
  echo "${now} $*" >> "${LOG_FILE}"
}

check_wifi() {
  log "Starting checks"
  # Make separate attempts with delays between then to cope with some transient
  # failures.
  for ((i = 0; i < ATTEMPTS; i++)); do
    if ping -c 5 -o -q "${INTERNAL_IP}" >& /dev/null; then
      log "attempt ${i}: internal ping succeeded"
      exit 0
    fi
    log "attempt ${i}: internal ping failed"
    sleep "${SLEEP_TIME}"
  done
}

reset_wifi() {
  ping -c 5 "${INTERNAL_IP}"
  echo "Reconnecting wifi"
  # Sometimes disabling the wifi is necessary to make everything work again :/
  networksetup -setairportpower "${WIFI_DEV}" off
  sleep 10
  networksetup -setairportpower "${WIFI_DEV}" on
  sleep 10
  networksetup -setairportnetwork "${WIFI_DEV}" "${SSID}" - \
    < "${HOME}/Documents/${SSID}-password.txt"
  sleep 30
  ping -c 5 "${INTERNAL_IP}"
}

main() {
  check_wifi
  log "All ${ATTEMPTS} attempts failed :("
  if [ "${DRYRUN}" == "no" ]; then
    set -x
    for i in 1 2 3; do
      if reset_wifi; then
        exit 0
      fi
    done
    log "All reset_wifi attempts failed"
  else
    echo "Dryrun is true, not making changes."
  fi
}

main "$@"