1 files changed, 147 insertions, 0 deletions
diff --git a/ddns-update-rfc2136 b/ddns-update-rfc2136
new file mode 100755
index 0000000..6bd07ce
--- /dev/null
+++ b/ddns-update-rfc2136
@@ -0,0 +1,147 @@
+#!/usr/bin/env python3
+
+import argparse
+import ipaddress
+import netifaces
+import logging
+import logging.handlers
+import os.path
+import socket
+import subprocess
+import sys
+
+
+def build_ip(ip_string):
+	try:
+		ip = ipaddress.ip_address(ip_string)
+	except ValueError:
+		log.error("manually specified address is invalid format: %s" % ip_string)
+		sys.exit(1)
+	except:
+		log.error(str(e))
+		sys.exit(1)
+
+	return ip
+
+def get_interface_addrs(iface, addrtype):
+	try:
+		iaddrs = netifaces.ifaddresses(iface)
+		i = iaddrs[addrtype]
+		log.debug("interface {} addrs of type {}: {}".format(iface,addrtype,i))
+	except ValueError as e:
+		log.debug("Exception class: {}".format(e.__class__))
+		log.error("No interface named {} found".format(iface))
+		sys.exit(1)
+	except KeyError as e:
+		log.debug("Exception class: {}".format(e.__class__))
+		log.error("No address of type {} found on interface {}".format(addrtype, iface))
+		sys.exit(1)
+	except Exception as e:
+		log.debug("Exception class: {}".format(e.__class__))
+		log.error(str(e))
+		sys.exit(1)
+
+	return i
+
+def build_nsupdate_cmd(server, zone, record, rrtype, ttl, addr):
+		log.debug("BNC: server: {}".format(server))
+		log.debug("BNC: zone: {}".format(zone))
+		log.debug("BNC: record: {}".format(record))
+		log.debug("BNC: rrtype: {}".format(rrtype))
+		log.debug("BNC: ttl: {}".format(ttl))
+		log.debug("BNC: addr: {}".format(addr))
+
+		cmdstr =  "server {}\n".format(server)
+		cmdstr += "zone {}\n".format(zone)
+		cmdstr += "update delete {} {}\n".format(record, rrtype)
+		cmdstr += "update add {} {} {} {}\n".format(record, ttl, rrtype, addr)
+		cmdstr += "send\n"
+		cmdstr += "quit\n"
+
+		return cmdstr
+
+def main():
+	ap = argparse.ArgumentParser(description="Update dynamic DNS records using RFC2136")
+	ap.add_argument("interface", help="interface to obtain IP from (for IPv6, takes the numerically first global address on the interface)")
+	ap.add_argument("record", help="DNS record to update")
+	ap.add_argument("zone", help="Zone name to update (e.g. example.com)")
+	ap.add_argument("server", help="Server to update (IP or FQDN)")
+	ap.add_argument("--v4", help="Update IPv4 A record", action="store_true", default=False)
+	ap.add_argument("--v6", help="Update IPv6 AAAA record (default)", action="store_true", default=True)
+	ap.add_argument("--addr4", help="Update A record with provided IP rather than detected IP (causes 'interface' to be ignored)")
+	ap.add_argument("--addr6", help="Update AAAA record with provided IP rather than detected IP (causes 'interface' to be ignored)")
+	ap.add_argument("--ttl", help="TTL to assign to record (default 300)", default=300)
+	ap.add_argument("--keyfile", help="Alternate location for key config file (default /etc/ddns-RECORD.key where RECORD is the record name provided as the argument)")
+	ap.add_argument("--debug", help="Enable debug logging", action="store_true", default=False)
+	args = ap.parse_args()
+
+	if args.debug:
+		log.setLevel(logging.DEBUG)
+	else:
+		log.setLevel(logging.ERROR)
+
+	if args.keyfile:
+		keyfile = args.keyfile
+	else:
+		keyfile = "/etc/ddns-{}.key".format(args.record)
+	log.debug("KEYFILE: {}".format(keyfile))
+
+	if args.v4:
+		addrtype = netifaces.AF_INET
+	else:
+		addrtype = netifaces.AF_INET6
+
+	ip = False
+	if args.addr4:
+		ip = build_ip(args.addr4)	
+
+	if args.addr6:
+		ip = build_ip(args.addr6)
+
+	try:
+		if not os.path.exists(keyfile):
+			raise Exception("missing key file {}".format(keyfile))
+
+		if ip:
+			addr = ip
+			log.debug("Manual IP: {}".format(addr))
+		else:
+			addrarr = get_interface_addrs(args.interface, addrtype)
+			addr = addrarr.pop(0)['addr']
+			log.debug("Found IP: {}".format(addr))
+
+		rrtype = "AAAA"
+		if args.v4:
+			rrtype = "A"
+
+		nsupdatecmd = build_nsupdate_cmd(args.server, args.zone, args.record, rrtype, args.ttl, addr)
+
+		nsupdate = subprocess.run(
+			"nsupdate -k {}".format(keyfile),
+			shell=True,
+			check=True,
+			input = bytes(nsupdatecmd,'utf-8'),
+			capture_output = True
+		)
+		
+		log.debug("nsupdate return code: {}".format(nsupdate.returncode))
+
+	except subprocess.CalledProcessError as e:
+		log.debug("Exception class: {}".format(e.__class__))
+		log.error("Error executing: " + e.cmd)
+		log.error("nsupdate stderr: " + e.stderr.decode("utf-8").strip())
+		sys.exit(1)
+	
+	except Exception as e:
+		log.debug("Exception class: {}".format(e.__class__))
+		log.error(str(e))    
+		sys.exit(1)
+
+if __name__ == "__main__":
+	log = logging.getLogger("ddns-update-rfc2136")
+	lh = logging.StreamHandler()
+	lf = logging.Formatter(fmt='%(name)s: %(levelname)s: %(message)s')
+	lh.setFormatter(lf)
+	log.addHandler(lh)
+	main()
+	sys.exit(0)