+requires_root() {
+ if [ "$(id -u)" -ne 0 ]; then
+ echo >&1 "ERROR: This command can only be used by root."
+ exit 1
+ fi
+}
+
+add_keys_with_verify_against_master_keyring() {
+ ADD_KEYRING=$1
+ MASTER=$2
+
+ if [ ! -f "$ADD_KEYRING" ]; then
+ echo "ERROR: '$ADD_KEYRING' not found"
+ return
+ fi
+ if [ ! -f "$MASTER" ]; then
+ echo "ERROR: '$MASTER' not found"
+ return
+ fi
+
+ # when adding new keys, make sure that the archive-master-keyring
+ # is honored. so:
+ # all keys that are exported must have a valid signature
+ # from a key in the $distro-master-keyring
+ add_keys=`$GPG_CMD --keyring $ADD_KEYRING --with-colons --list-keys | grep ^pub | cut -d: -f5`
+ master_keys=`$GPG_CMD --keyring $MASTER --with-colons --list-keys | grep ^pub | cut -d: -f5`
+ for add_key in $add_keys; do
+ ADDED=0
+ for master_key in $master_keys; do
+ if $GPG_CMD --keyring $ADD_KEYRING --list-sigs --with-colons $add_key | grep ^sig | cut -d: -f5 | grep -q $master_key; then
+ $GPG_CMD --quiet --batch --keyring $ADD_KEYRING --export $add_key | $GPG --import
+ ADDED=1
+ fi
+ done
+ if [ $ADDED = 0 ]; then
+ echo >&2 "Key '$add_key' not added. It is not signed with a master key"
+ fi
+ done
+}
+
+# update the current archive signing keyring from a network URI
+# the archive-keyring keys needs to be signed with the master key
+# (otherwise it does not make sense from a security POV)
+net_update() {
+ if [ -z "$ARCHIVE_KEYRING_URI" ]; then
+ echo >&2 "ERROR: Your distribution is not supported in net-update as no uri for the archive-keyring is set"
+ exit 1
+ fi
+ requires_root
+ # in theory we would need to depend on wget for this, but this feature
+ # isn't useable in debian anyway as we have no keyring uri nor a master key
+ if ! which wget >/dev/null 2>&1; then
+ echo >&2 "ERROR: an installed wget is required for a network-based update"
+ exit 1
+ fi
+ if [ ! -d /var/lib/apt/keyrings ]; then
+ mkdir -p /var/lib/apt/keyrings
+ fi
+ keyring=/var/lib/apt/keyrings/$(basename $ARCHIVE_KEYRING)
+ old_mtime=0
+ if [ -e $keyring ]; then
+ old_mtime=$(stat -c %Y $keyring)
+ fi
+ (cd /var/lib/apt/keyrings; wget -q -N $ARCHIVE_KEYRING_URI)
+ if [ ! -e $keyring ]; then
+ return
+ fi
+ new_mtime=$(stat -c %Y $keyring)
+ if [ $new_mtime -ne $old_mtime ]; then
+ echo "Checking for new archive signing keys now"
+ add_keys_with_verify_against_master_keyring $keyring $MASTER_KEYRING
+ fi
+}