integrate with cron daemon

3 files changed, 37 insertions, 1 deletions

diff --git a/0tdns_crontab b/0tdns_crontab
new file mode 100644
index 0000000..306d439
--- /dev/null
+++ b/0tdns_crontab
@@ -0,0 +1 @@
+0 * * * * /usr/sbin/hourly.sh # <AUTO_GENERATED_0TDNS_ENTRY> do not remove this '<>' tag
diff --git a/setup.sh b/setup.sh
index 959a48f..8159db6 100755
--- a/setup.sh
+++ b/setup.sh
@@ -1,9 +1,31 @@
 #!/bin/sh
 
+# https://stackoverflow.com/questions/2990414/echo-that-outputs-to-stderr
+errcho(){ >&2 echo "$@"; }
+
 # run this script as root, once, at installation
+if id -u 0tdns > /dev/null 2>&1; then
+    errcho "User 0tdns already exists."
+    errcho "Do you have Zero Trust DNS already set up?"
+    errcho "If so, you need to uninstall it properly"
+    errcho "(e.g. via provided uninstall.sh script)"
+    errcho "before setting it up again"
+    exit 1
+fi
 
-# more will go here (e.g. initialization of postgres database)
+if [ `id -u` != 0 ]; then
+    errcho "This script needs to be run as root"
+    exit 1
+fi
 
 # part of the program running inside network namespace
 # will run under this user
 useradd --system 0tdns
+
+# crontab automatically adds a 'DO NOT EDIT' header to
+# crontab file; if we don't remove it every time - headers
+# will accumulate :/ (not on Debian, though)
+# line we want to add to crontab is in 0tdns_crontab file
+crontab -l 2> /dev/null |
+    grep -vE '^# DO NOT EDIT THIS FILE|^# \(- installed on .*\)|^# \(Cron version .*\)' |
+    cat - 0tdns_crontab | crontab
diff --git a/uninstall.sh b/uninstall.sh
index 7c14cba..fee17b2 100755
--- a/uninstall.sh
+++ b/uninstall.sh
@@ -1,10 +1,23 @@
 #!/bin/sh
 
+# https://stackoverflow.com/questions/2990414/echo-that-outputs-to-stderr
+errcho(){ >&2 echo "$@"; }
+
 # run as root, obviously
+if [ `id -u` != 0 ]; then
+    errcho "This script needs to be run as root"
+    exit 1
+fi
 
 # revert what was done in setup.sh
 userdel 0tdns
 
+# remove our crontab entry marked with '<AUTO_GENERATED_0TDNS_ENTRY>'
+# we also remove the 'DO NOT EDIT' header, as in setup.sh
+crontab -l 2> /dev/null |
+    grep -vE '^# DO NOT EDIT THIS FILE|^# \(- installed on .*\)|^# \(Cron version .*\)' |
+    grep -v '<AUTO_GENERATED_0TDNS_ENTRY>' | crontab
+
 # if told to - also revert what was done in install.sh
 if [ "x$1" = "x--delete-files" ]; then
     rm -r /var/lib/0tdns/