T4815: Fix various name server config issues

1. When a PPPoE session is connected, `pppd` will update
   `/etc/resolv.conf` regardless of `system name-server` option unless `no-peer-dns` is set.
   This is because `pppd` vendors scripts `/etc/ppp/ip-up.d/0000usepeerdns` and `/etc/ppp/ip-down.d/0000usepeerdns`,
   which updates `/etc/resolv.conf` on PPPoE connection and reverts the change on disconnection.
   This PR removes those scripts and adds custom scripts to update name server entries through `vyos-hostsd` instead.

2. There is a typo in `/etc/dhcp/dhclient-enter-hooks.d/04-vyos-resolvconf, which misspells variable name `new_dhcp6_name_servers` as `new_dhcpv6_name_servers`.
   This causes IPv6 name server entries in `vyos-hostsd` not updated
   when dhclient receives nameservers from DHCPv6.

3. Regular expressions in scripts under `/etc/dhcp/dhclient-enter-hooks.d` and
   `/etc/dhcp/dhclient-exit-hooks.d/` are not enclosed in `^$`, so those
   IPv4 related branches (like `BOUND`) could be mistakenly executed when an IPv6
   reason (like `BOUND6`) is given.

3 files changed, 7 insertions, 7 deletions

diff --git a/src/etc/dhcp/dhclient-enter-hooks.d/04-vyos-resolvconf b/src/etc/dhcp/dhclient-enter-hooks.d/04-vyos-resolvconf
index b1902b585..518abeaec 100644
--- a/src/etc/dhcp/dhclient-enter-hooks.d/04-vyos-resolvconf
+++ b/src/etc/dhcp/dhclient-enter-hooks.d/04-vyos-resolvconf
@@ -33,8 +33,8 @@ if /usr/bin/systemctl -q is-active vyos-hostsd; then
         if [ -n "$new_dhcp6_name_servers" ]; then
             logmsg info "Deleting nameservers with tag \"dhcpv6-$interface\" via vyos-hostsd-client"
             $hostsd_client --delete-name-servers --tag "dhcpv6-$interface"
-            logmsg info "Adding nameservers \"$new_dhcpv6_name_servers\" with tag \"dhcpv6-$interface\" via vyos-hostsd-client"
-            $hostsd_client --add-name-servers $new_dhcpv6_name_servers --tag "dhcpv6-$interface"
+            logmsg info "Adding nameservers \"$new_dhcp6_name_servers\" with tag \"dhcpv6-$interface\" via vyos-hostsd-client"
+            $hostsd_client --add-name-servers $new_dhcp6_name_servers --tag "dhcpv6-$interface"
             hostsd_changes=y
         fi
 
diff --git a/src/etc/dhcp/dhclient-exit-hooks.d/01-vyos-cleanup b/src/etc/dhcp/dhclient-exit-hooks.d/01-vyos-cleanup
index ad6a1d5eb..da1bda137 100644
--- a/src/etc/dhcp/dhclient-exit-hooks.d/01-vyos-cleanup
+++ b/src/etc/dhcp/dhclient-exit-hooks.d/01-vyos-cleanup
@@ -8,7 +8,7 @@ hostsd_changes=
 /usr/bin/systemctl -q is-active vyos-hostsd
 hostsd_status=$?
 
-if [[ $reason =~ (EXPIRE|FAIL|RELEASE|STOP) ]]; then
+if [[ $reason =~ ^(EXPIRE|FAIL|RELEASE|STOP)$ ]]; then
     if [[ $hostsd_status -eq 0 ]]; then
         # delete search domains and nameservers via vyos-hostsd
         logmsg info "Deleting search domains with tag \"dhcp-$interface\" via vyos-hostsd-client"
@@ -96,7 +96,7 @@ if [[ $reason =~ (EXPIRE|FAIL|RELEASE|STOP) ]]; then
     fi
 fi
 
-if [[ $reason =~ (EXPIRE6|RELEASE6|STOP6) ]]; then
+if [[ $reason =~ ^(EXPIRE6|RELEASE6|STOP6)$ ]]; then
     if [[ $hostsd_status -eq 0 ]]; then
         # delete search domains and nameservers via vyos-hostsd
         logmsg info "Deleting search domains with tag \"dhcpv6-$interface\" via vyos-hostsd-client"
diff --git a/src/etc/dhcp/dhclient-exit-hooks.d/vyatta-dhclient-hook b/src/etc/dhcp/dhclient-exit-hooks.d/vyatta-dhclient-hook
index eeb8b0782..49bb18372 100644
--- a/src/etc/dhcp/dhclient-exit-hooks.d/vyatta-dhclient-hook
+++ b/src/etc/dhcp/dhclient-exit-hooks.d/vyatta-dhclient-hook
@@ -8,12 +8,12 @@
 # This program is free software; you can redistribute it and/or modify
 # it under the terms of the GNU General Public License version 2 as
 # published by the Free Software Foundation.
-# 
+#
 # This program is distributed in the hope that it will be useful, but
 # WITHOUT ANY WARRANTY; without even the implied warranty of
 # MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 # General Public License for more details.
-# 
+#
 # This code was originally developed by Vyatta, Inc.
 # Portions created by Vyatta are Copyright (C) 2006, 2007, 2008 Vyatta, Inc.
 # All Rights Reserved.
@@ -23,7 +23,7 @@
 RUN="yes"
 
 proto=""
-if [[ $reason =~ (REBOOT6|INIT6|EXPIRE6|RELEASE6|STOP6|INFORM6|BOUND6|REBIND6|DELEGATED6) ]]; then
+if [[ $reason =~ ^(REBOOT6|INIT6|EXPIRE6|RELEASE6|STOP6|INFORM6|BOUND6|REBIND6|DELEGATED6)$ ]]; then
         proto="v6"
 fi