From 4523e9c897b3fa8d12c1b16c830c01820fee5583 Mon Sep 17 00:00:00 2001
From: zsdc <taras@vyos.io>
Date: Thu, 26 Aug 2021 18:15:36 +0300
Subject: wireguard: T3763: Added check for listening port availability
Each wireguard interface requires a unique port for in and out
connections. This commit adds the new `vyos.util` function -
`check_port_availability`, and uses it to be sure that a port
that is planned to be used for wireguard interface is truly
available and not used by any other services (not only other
wireguard interfaces).
---
python/vyos/util.py | 39 +++++++++++++++++++++++++++++++++++++++
1 file changed, 39 insertions(+)
(limited to 'python/vyos')
diff --git a/python/vyos/util.py b/python/vyos/util.py
index 8af46a6ee..fc2834a97 100644
--- a/python/vyos/util.py
+++ b/python/vyos/util.py
@@ -819,3 +819,42 @@ def is_systemd_service_running(service):
Copied from: https://unix.stackexchange.com/a/435317 """
tmp = cmd(f'systemctl show --value -p SubState {service}')
return bool((tmp == 'running'))
+
+def check_port_availability(ipaddress, port, protocol):
+ """
+ Check if port is available and not used by any service
+ Return False if a port is busy or IP address does not exists
+ Should be used carefully for services that can start listening
+ dynamically, because IP address may be dynamic too
+ """
+ from socketserver import TCPServer, UDPServer
+ from ipaddress import ip_address
+
+ # verify arguments
+ try:
+ ipaddress = ip_address(ipaddress).compressed
+ except:
+ print(f'The {ipaddress} is not a valid IPv4 or IPv6 address')
+ return
+ if port not in range(1, 65536):
+ print(f'The port number {port} is not in the 1-65535 range')
+ return
+ if protocol not in ['tcp', 'udp']:
+ print(
+ f'The protocol {protocol} is not supported. Only tcp and udp are allowed'
+ )
+ return
+
+ # check port availability
+ try:
+ if protocol == 'tcp':
+ server = TCPServer((ipaddress, port), None, bind_and_activate=True)
+ if protocol == 'udp':
+ server = UDPServer((ipaddress, port), None, bind_and_activate=True)
+ server.server_close()
+ return True
+ except:
+ print(
+ f'The {protocol} port {port} on the {ipaddress} is busy or unavailable'
+ )
+ return False
--
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