From 584f418ec1ae3f0b5e09c10133c82578d78a3e03 Mon Sep 17 00:00:00 2001 From: Peter Korsgaard Date: Wed, 26 Jun 2013 15:01:46 +0200 Subject: [PATCH] busybox: udhcpc.script: fix resolv.conf handling with multiple interfaces When udhcpc is used on multiple network devices at the same time (or a mix of dhcp and fixed configuration), /etc/resolv.conf should contain the union of information from all the interfaces. Currently that's not the case. The udhcpc script simply overwrites resolv.conf with the information from the specific interface on each dhcp bound/renew event. Fix it by tagging lines with the interface they came from when added, and drop the affected lines on deconfig/renew. As /etc/resolv.conf is often a symlink to /tmp (and rootfs might be read only), special care has to be taken when it is updated. Notice that I'm not really aware of any official documentation requiring that '#' comments in /etc/resolv.conf must be supported, but atleast glibc and uClibc do. Signed-off-by: Peter Korsgaard --- package/busybox/udhcpc.script | 19 ++++++++++++++++--- 1 file changed, 16 insertions(+), 3 deletions(-) diff --git a/package/busybox/udhcpc.script b/package/busybox/udhcpc.script index f7beb56a08..43742fbd53 100755 --- a/package/busybox/udhcpc.script +++ b/package/busybox/udhcpc.script @@ -13,6 +13,13 @@ case "$1" in /sbin/ifconfig $interface up /sbin/ifconfig $interface 0.0.0.0 + # drop info from this interface + # resolv.conf may be a symlink to /tmp/, so take care + TMPFILE=$(mktemp) + grep -vE "# $interface\$" $RESOLV_CONF > $TMPFILE + cat $TMPFILE > $RESOLV_CONF + rm -f $TMPFILE + if [ -x /usr/sbin/avahi-autoipd ]; then /usr/sbin/avahi-autoipd -k $interface fi @@ -41,11 +48,17 @@ case "$1" in done fi - echo -n > $RESOLV_CONF - [ -n "$domain" ] && echo search $domain >> $RESOLV_CONF + # drop info from this interface + # resolv.conf may be a symlink to /tmp/, so take care + TMPFILE=$(mktemp) + grep -vE "# $interface\$" $RESOLV_CONF > $TMPFILE + cat $TMPFILE > $RESOLV_CONF + rm -f $TMPFILE + + [ -n "$domain" ] && echo "search $domain # $interface" >> $RESOLV_CONF for i in $dns ; do echo adding dns $i - echo nameserver $i >> $RESOLV_CONF + echo "nameserver $i # $interface" >> $RESOLV_CONF done ;; esac -- 2.30.2