Timotej Lazar
8e3772e475
To avoid dnsmasq writing out the whole leasefile on each request before replying. This gets slow on high‐latency storage. Also tweak DNS updates a bit.
76 lines
2 KiB
Django/Jinja
76 lines
2 KiB
Django/Jinja
#!/bin/sh
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# This script replaces the dnsmasq leasefile with an sqlite database
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# for performance on slow storage, and updates DNS records for
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# assigned addresses.
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cmd="${1}"
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# dnsmasq calls this script on startup for each known lease, ignore it
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[ "${cmd}" != "init" ] && [ -z "${DNSMASQ_INTERFACE}" ] && exit 0
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# parameters
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db=/var/lib/misc/dnsmasq.leases.db
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domain={{ domain }}
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ldap_user={{ password.ldap_user }}
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ttl=3600
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# sanitize input
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mac="${2//[![:xdigit:]:]/}"
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ipv4="${3//[![:digit:].]/}"
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hostname="${4//[![:alnum:]_-]/}"
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client_id="${DNSMASQ_CLIENT_ID//[![:xdigit:]:]/}"
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# construct SQL to query or update leases, and nsupdate script to update DNS records
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dns=""
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sql=""
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case "${cmd}" in
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"init")
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# init runs as root, so ensure the dnsmasq user can write to database later
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touch "${db}"
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chown dnsmasq:dnsmasq "${db}"
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setfacl -m u:dnsmasq:rwx "$(dirname ${db})"
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setfacl -m u:dnsmasq:r "/etc/krb5.keytab" # needed for DNS updates
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# ensure the leases table exists, and get all leases from it
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sql="CREATE TABLE IF NOT EXISTS leases (
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ipv4 TEXT PRIMARY KEY NOT NULL,
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mac TEXT NOT NULL,
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hostname TEXT NOT NULL,
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client_id TEXT NOT NULL,
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renewed INTEGER NOT NULL);
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SELECT renewed, mac, ipv4, hostname, client_id FROM leases;"
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;;
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"add" | "old")
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# add or update the lease
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sql="INSERT INTO leases
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VALUES ('${ipv4}', '${mac}', '${hostname:-*}', '${client_id:-*}', unixepoch())
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ON CONFLICT(ipv4) DO UPDATE SET renewed = unixepoch();"
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# add or update the DNS record
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if [ -n "${hostname}" ] ; then
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dns="update add ${hostname}.${domain} ${ttl} A ${ipv4}\n"
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fi
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if [ -n "${DNSMASQ_OLD_HOSTNAME}" ] ; then
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dns="${dns}update del ${DNSMASQ_OLD_HOSTNAME}.${domain}\n"
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fi
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;;
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"del")
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# delete the lease
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sql="DELETE FROM leases WHERE ipv4 = '${ipv4}';"
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# TODO probably delete the DNS record
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;;
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esac
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# update lease database
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if [ -n "${sql}" ]; then
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sqlite3 -separator " " "${db}" "${sql}"
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fi
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# update DNS records
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if [ -n "${dns}" ]; then
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kinit -k "${ldap_user}"
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echo -e "${dns}send" | nsupdate -g
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fi
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