#!/bin/selfclean /bin/sh
#
# This script monitors /tmp/conman/command* /tmp/conman/access_point_enabled*
# and starts or stops access points accordingly.
#
# Also adds routes based on gateways output by dhclient-script.
#
. /etc/utils.sh

if experiment BigInitRwnd; then
  initrwnd='initrwnd 1000'
else
  initrwnd=
fi

TMP_DIR="/tmp/conman"
CONFIG_DIR="/config/conman"

mkdir -p $TMP_DIR
mkdir -p $CONFIG_DIR

iplog() {
  echo "running: ip" "$@" >&2
  ip "$@"
}

# extension is either "interface_suffix.band" or just "band"
stopap() {
  local extension="$1"

  bands="2.4 5"
  for band in $bands; do
    if [ "$extension" = "$band" ]; then
      break
    else
      if endswith "$extension" "$band"; then
        interface_suffix=${extension%.$band}
        break
      else
        interface_suffix=
        band=
      fi
    fi
  done
  if [ -z "$band" ]; then
    echo "Failed to parse extension '$extension'"
    return
  fi
  flags="--band $band"
  if [ -n "$interface_suffix" ]; then
    flags="$flags --interface-suffix "$interface_suffix""
  fi
  if ! $(wifi stopap $flags); then
    echo "Failed to stop access point for '$extension'"
    false
  fi
}

# Check all existing command and gateway files, then monitor those as well as
# access_point files for changes.
{ cd "$TMP_DIR" && ls gateway.* command.* subnet.*;
  cd "$CONFIG_DIR" && ls command.*;
  watch-dir $TMP_DIR $CONFIG_DIR; } |
while read filename; do
  route_type=
  if startswith "$filename" "subnet."; then
    route_type="subnet"
  fi
  if startswith "$filename" "gateway."; then
    route_type="gateway"
  fi
  if [ "$route_type" != "" ]; then
    filepath="$TMP_DIR/$filename"
    if [ -e "$filepath" ]; then
      interface=${filename#${route_type}.}
      # Trying to add a default route without a subnet route fails, because
      # there is no route to the gateway.  So just always update the subnet
      # route first, and then update the default route if we know the gateway.
      subnet_filepath="$TMP_DIR/subnet.$interface"
      if [ -e "$subnet_filepath" ]; then
        subnet=$(cat "$subnet_filepath")
        # If this script is running as conman's deathrattle, it is possible that
        # there is a wifi route up too and also that acs_autoprovisioning is
        # enabled.  Between deleting and re-adding this default route, traffic
        # could be routed via wifi, and if autoprovisioning is enabled and the
        # wifi connection is to a neighbor's RG then the ACS could provision this
        # device to the neighbor.  Removing the file which enables that
        # autoprovisioning here prevents that from happening.
        rm -f /tmp/conman/acs_autoprovisioning

        # Remove all subnet routes on $interface except default, with 'scope
        # link', then recreate the desired subnet route.
        iplog -4 route show dev "$interface" |
        while read route junk; do
          # Ignore the RFC2365 multicast route.
          if ! startswith "$route" "239"; then
            if contains "$route" "/" && [ "$route" != "$subnet" ]; then
              iplog -4 route del "$route" dev "$interface"
            fi
          fi
        done
        iplog -4 route add "$subnet" dev "$interface" $initrwnd

        gateway_filepath="$TMP_DIR/gateway.$interface"
        if [ -e "$gateway_filepath" ]; then
          gateway=$(cat "$gateway_filepath")
          if ! ip route dev "$interface" | grep default | grep "via $gateway"; then
            iplog -4 route del default dev "$interface"
            iplog -4 route add default via "$gateway" dev "$interface" $initrwnd
          fi
        fi
      fi
    fi
    continue
  fi

  command=
  access_point=
  # This assumes command files in /tmp (for provisioning networks) will have an
  # interface suffix, and those in /config (the user's WLAN) will not.  Or, more
  # generally, that for any given filename, files of that filename can only
  # appear in one of ($TMP_DIR, $CONFIG_DIR).
  if [ -e "$CONFIG_DIR/$filename" ]; then
    which_dir="$CONFIG_DIR"
  else
    which_dir="$TMP_DIR"
  fi

  if startswith "$filename" "command."; then
    extension=${filename#command.}
    command="$which_dir/$filename"
    access_point="$which_dir/access_point.$extension"
  else
    if startswith "$filename" "access_point."; then
      extension=${filename#access_point.}
      command="$which_dir/command.$extension"
      access_point="$which_dir/$filename"
    fi
  fi

  if [ -e "$command" ] && [ -e "$access_point" ]; then
    if ! run_command_lines $command; then
      echo "Failed to start access point for '$extension'"
    fi
  else
    stopap "$extension"
  fi
done