main/wpa_supplicant: refactor wpa_cli.sh

udhcpc doesn't have link beat detection and the purposes of this script
is making udhcpc acquire a new lease when connecting to an access point.

The previous version of this script achieved that goal by running
ifdown/ifup which is pretty ugly and never worked properly (at least
with my setup). A better solution for acquiring a DHCP lease when
connecting to a new AP is sending a SIGUSR1 signal to the udhcpc running
on the affected interfaces, this solution is implemented in this commit.

Together with the wpa_cli OpenRC service added in the previous commit
this makes using udhcpc on laptops very convenient.

See also: cc8f61f6330f49f1e2522e6fbed88e84e47190c3

2 files changed, 23 insertions, 16 deletions

diff --git a/main/wpa_supplicant/APKBUILD b/main/wpa_supplicant/APKBUILD
index 5d983e7f46b..023d06e4e44 100644
--- a/main/wpa_supplicant/APKBUILD
+++ b/main/wpa_supplicant/APKBUILD
@@ -2,7 +2,7 @@
 # Maintainer: Natanael Copa <ncopa@alpinelinux.org>
 pkgname=wpa_supplicant
 pkgver=2.6
-pkgrel=10
+pkgrel=11
 pkgdesc="A utility providing key negotiation for WPA wireless networks"
 url="https://w1.fi/wpa_supplicant/"
 arch="all"
@@ -113,4 +113,4 @@ a0ac905ef23af18f1899a797e18157a54fa509c7cc3c59583de768a493d750876bbc0a89237373b6
 e98edc1ecec91335d515c50cac8816e3f6eef139aba574bcf0c6c20c131ef0de40aa657a33d07af09ab28245471a09cb6b3e29b306e48f46d335a0c47a0a56c4  libressl.patch
 2be055dd1f7da5a3d8e79c2f2c0220ddd31df309452da18f290144d2112d6dbde0fc633bb2ad02c386a39d7785323acaf5f70e5969995a1e8303a094eb5fe232  eloop.patch
 6707991f9a071f2fcb09d164d31d12b1f52b91fbb5574b70b8d6f9727f72bbe42b03dd66d10fcc2126f5b7e49ac785657dec90e88b4bf54a9aa5638582f6e505  config
-44d33cfe419cdb65cc14f2ac05aa9f8a1b9f2f432181e498071e41ef835662db1e4c5142adf4cfab2475e7b606696169936bd159d1d711f803322db93f242361  wpa_cli.sh"
+212c4265afce2e72b95a32cd785612d6c3e821b47101ead154136d184ac4add01434ada6c87edbb9a98496552e76e1a4d79c6b5840e3a5cfe5e6d602fceae576  wpa_cli.sh"
diff --git a/main/wpa_supplicant/wpa_cli.sh b/main/wpa_supplicant/wpa_cli.sh
index 0a5a6cc036b..dd9bc2ca467 100644
--- a/main/wpa_supplicant/wpa_cli.sh
+++ b/main/wpa_supplicant/wpa_cli.sh
@@ -1,33 +1,40 @@
 #!/bin/sh
-# Distributed under the terms of the BSD License.
-# Copyright (c) 2015 Sören Tempel <soeren+alpine@soeren-tempel.net>
+# Script for using udhcpc (started by ifup) with wpa_supplicant.
+#
+# Distributed under the same license as wpa_supplicant itself.
+# Copyright (c) 2015,2018 Sören Tempel <soeren+alpine@soeren-tempel.net>
 
-IFUP="/sbin/ifup"
-IFDOWN="/sbin/ifdown"
-
-if [ -z "${1}" -o -z "${2}" ]; then
+if [ $# -ne 2 ]; then
 	logger -t wpa_cli "this script should be called from wpa_cli(8)"
 	exit 1
-elif ! [ -x "${IFUP}" -a -x "${IFDOWN}" ]; then
-	logger -t wpa_cli "${IFUP} or ${IFDOWN} doesn't exist"
-	exit 1
 fi
 
 IFNAME="${1}"
 ACTION="${2}"
+SIGNAL=""
+DHCPID=""
+
+# PID file created by the busybox ifup applet for udhcpc.
+DHCPIDFILE="/var/run/udhcpc.${IFNAME}.pid"
+
+if [ ! -e "${DHCPIDFILE}" ]; then
+	logger -t wpa_cli "udhcpc isn't running for interface '${IFNAME}'"
+	exit 1
+fi
 
-EXEC=""
+logger -t wpa_cli "interface ${IFNAME} ${ACTION}"
 case "${ACTION}" in
 	CONNECTED)
-		EXEC="${IFUP}"
+		SIGNAL="USR1"
 		;;
 	DISCONNECTED)
-		EXEC="${IFDOWN}"
+		SIGNAL="USR2"
 		;;
 	*)
 		logger -t wpa_cli "unknown action '${ACTION}'"
 		exit 1
 esac
 
-logger -t wpa_cli "interface ${IFNAME} ${ACTION}"
-${EXEC} "${IFNAME}" || logger -t wpa_cli "executing '${EXEC}' failed"
+read -r DHCPID < "${DHCPIDFILE}"
+kill -${SIGNAL} "${DHCPID}" || logger -t wpa_cli \
+	"Couldn't send '${SIGNAL}' to '${DHCPID}'"