From c3d133a75e764b6628644d20594031794799037f Mon Sep 17 00:00:00 2001
From: Tony Blyler <me@tonyblyler.com>
Date: Mon, 10 May 2021 00:16:32 -0400
Subject: [PATCH] Add README.md and some scripts to get DHCPD hosts into
 unbound for DNS

---
 README.md                         |  3 +
 cron/unbound-dhcpd-updater        | 28 +++++++++
 dhcpd/list_active_assignments     | 95 +++++++++++++++++++++++++++++++
 unbound/local-data-file-generator | 15 +++++
 4 files changed, 141 insertions(+)
 create mode 100644 README.md
 create mode 100755 cron/unbound-dhcpd-updater
 create mode 100644 dhcpd/list_active_assignments
 create mode 100755 unbound/local-data-file-generator

diff --git a/README.md b/README.md
new file mode 100644
index 0000000..7374924
--- /dev/null
+++ b/README.md
@@ -0,0 +1,3 @@
+# openbsd-tools
+
+My personal OpenBSD-specific scripts, probably for my router.
diff --git a/cron/unbound-dhcpd-updater b/cron/unbound-dhcpd-updater
new file mode 100755
index 0000000..56f8fac
--- /dev/null
+++ b/cron/unbound-dhcpd-updater
@@ -0,0 +1,28 @@
+#!/bin/sh
+set -eu
+
+readonly DHCPD_CONF_FILE='/etc/dhcpd.conf'
+readonly DHCPD_LEASES_FILE='/var/db/dhcpd.leases'
+readonly UNBOUND_LOCAL_DATA_FILE='/var/unbound/etc/local-data-dhcpd.conf'
+UNBOUND_LOCAL_DATA_FILE_TMP="$(mktemp)"
+readonly UNBOUND_LOCAL_DATA_FILE_TMP
+
+get_file_modify_time() {
+	stat -f %m "$1"
+}
+
+if [ -e "$UNBOUND_LOCAL_DATA_FILE" ]; then
+	UNBOUND_LOCAL_DATA_FILE_MODIFY_TIME="$(get_file_modify_time "$UNBOUND_LOCAL_DATA_FILE")"
+
+	if [ "$UNBOUND_LOCAL_DATA_FILE_MODIFY_TIME" -gt "$(get_file_modify_time "$DHCPD_CONF_FILE")" ]; then
+		if [ "$UNBOUND_LOCAL_DATA_FILE_MODIFY_TIME" -gt "$(get_file_modify_time "$DHCPD_LEASES_FILE")" ]; then
+			exit 0
+		fi
+	fi
+fi
+
+../dhcpd/list_active_assignments | ../unbound/local-data-file-generator > "$UNBOUND_LOCAL_DATA_FILE_TMP"
+
+mv "$UNBOUND_LOCAL_DATA_FILE_TMP" "$UNBOUND_LOCAL_DATA_FILE"
+
+rcctl reload unbound
diff --git a/dhcpd/list_active_assignments b/dhcpd/list_active_assignments
new file mode 100644
index 0000000..4684324
--- /dev/null
+++ b/dhcpd/list_active_assignments
@@ -0,0 +1,95 @@
+#!/bin/sh
+set -eu
+
+readonly DHCPD_CONF_FILE="${DHCPD_CONF_FILE:-/etc/dhcpd.conf}"
+readonly DHCPD_LEASES_FILE="${DHCPD_LEASES_FILE:-/var/db/dhcpd.leases}"
+
+DHCPD_CONF_FILE_AWK_SCRIPT=$(cat << 'EOF'
+/^[ \t]*host[ \t]+[^ \t]+[ \t]+\{[ \t]*$/ {
+	ip = ""
+	hostname = $2
+	next
+}
+
+/^[ \t]*fixed-address[ \t]+([0-9]{1,3}\.){3}[0-9]{1,3}[ \t]*;[ \t]*$/ {
+	ip = substr($2, 1, length($2)-1)
+	next
+}
+
+/\}/ {
+	if (hostname && ip) {
+		print hostname "\t" ip
+	}
+
+	hostname = ""
+	ip = ""
+	next
+}
+EOF
+)
+
+readonly DHCPD_CONF_FILE_AWK_SCRIPT
+
+DHCPD_LEASES_FILE_AWK_SCRIPT=$(cat << 'EOF'
+function parse_datetime(datetime) {
+	command = "date -j -f \"%w %Y/%m/%d %H:%M:%S %Z;\" +%s \"" datetime "\""
+	if (command | getline unix_time < 0) {
+		exit 1
+	}
+
+	close(command)
+
+	return unix_time
+}
+
+/^[ \t]*lease[ \t]+([0-9]{1,3}\.){3}[0-9]{1,3}[ \t]+\{[ \t]*$/ {
+	ip = $2
+	next
+}
+
+/^[ \t]*(starts|ends)[ \t]+[0-6][ \t]+[0-9]+\/[0-9]+\/[0-9]+[ \t]+[0-9]+:[0-9]+:[0-9]+([ \t]+[a-zA-Z0-9]+)?[ \t]*;[ \t]*$/ {
+	if ($1 == "starts") {
+		$1 = ""
+		# remove the leading space caused by setting $1 to ""
+		starts = parse_datetime(substr($0, 2))
+	} else {
+		$1 = ""
+		# remove the leading space caused by setting $1 to ""
+		ends = parse_datetime(substr($0, 2))
+	}
+
+	next
+}
+
+/^[ \t]*(client-)?hostname[ \t]+\"[^\"]+\"[ \t]*;[ \t]*$/ {
+	hostname = gensub("\"|;", "", "g", $2)
+	next
+}
+
+/^[ \t]*abandoned[ \t]*;[ \t]*$/ {
+	abandoned = 1
+	next
+}
+
+/\}/ {
+	now = systime()
+
+	if (!abandoned && hostname && ip && starts && ends && now >= starts && now < ends) {
+		print hostname "\t" ip
+	}
+
+	hostname = ""
+	ip = ""
+	starts = 0
+	ends = 0
+	abandoned = 0
+}
+EOF
+)
+
+readonly DHCPD_LEASES_FILE_AWK_SCRIPT
+
+(
+	awk "${DHCPD_CONF_FILE_AWK_SCRIPT}" "${DHCPD_CONF_FILE}"
+	awk "${DHCPD_LEASES_FILE_AWK_SCRIPT}" "${DHCPD_LEASES_FILE}"
+) | sort -u | column -c 2 -t
diff --git a/unbound/local-data-file-generator b/unbound/local-data-file-generator
new file mode 100755
index 0000000..01559b8
--- /dev/null
+++ b/unbound/local-data-file-generator
@@ -0,0 +1,15 @@
+#!/bin/sh
+
+set -eu
+
+AWK_SCRIPT=$(cat << 'EOF'
+/^[ \t]*[^ \t]+[ \t]+([0-9]{1,3}\.){3}[0-9]{1,3}[ \t]*$/ {
+	print "local-data: \"" $1 " A " $2 "\""
+	print "local-data-ptr: \"" $2 " " $1 "\""
+}
+EOF
+)
+
+readonly AWK_SCRIPT
+
+awk "$AWK_SCRIPT"