test: new infamy DHCP server class

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

test/infamy/dhcp.py

@@ -0,0 +1,55 @@
+"""Start a DHCP server in the background"""
+import os
+import subprocess
+import ipaddress
+
+class Server:
+    config_file = '/tmp/udhcpd.conf'
+    leases_file = '/tmp/udhcpd.leases'
+
+    def __init__(self, netns, subnet='192.168.0.0', netmask='255.255.255.0', ip='192.168.0.20'):
+        self.process = None
+        self.netns = netns
+        self._create_files(subnet, netmask, ip)
+
+    def __del__(self):
+        print(self.config_file)
+        #os.unlink(self.config_file)
+        #os.unlink(self.leases_file)
+
+    def __enter__(self):
+        self.start()
+
+    def __exit__(self, _, __, ___):
+        self.stop()
+
+    def _create_files(self, subnet, netmask, ip):
+        f = open(self.leases_file, "w")
+        f.close()
+
+        with open(self.config_file, 'w') as f:
+            f.write(f'''# Generated by Infamy DHCP
+lease_file {self.leases_file}
+interface iface
+start {ip}
+end {ip}
+max_leases 1
+option subnet {netmask}
+option lease 864000
+''')
+
+    def get_pid(self):
+        return self.process.pid
+
+    def start(self):
+        if not os.path.exists(self.config_file):
+            raise Exception("Config file does not exist. Please create it first.")
+        cmd = f"udhcpd -f {self.config_file}"
+        print(f"Starting: {cmd}")
+        self.process = self.netns.popen(cmd.split(" "))
+
+    def stop(self):
+        if self.process:
+            self.process.terminate()
+            self.process.wait()
+            self.process = None