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Feature: DHCP scope #23

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Feature: DHCP scope #23

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74 changes: 50 additions & 24 deletions ptftplib/dhcpserver.py
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Original file line number Diff line number Diff line change
Expand Up @@ -107,6 +107,12 @@ def mac_from_response(resp):
return ip_from_response(ip), ip_from_response(mask), mac_from_response(mac)


def get_ips_in_range(start, end):
start = struct.unpack('>I', socket.inet_aton(start))[0]
end = struct.unpack('>I', socket.inet_aton(end))[0]
return [socket.inet_ntoa(struct.pack('>I', i)) for i in range(start, end)]


def _dhcp_options(options):
"""Generate a sequence of DHCP options from a raw byte stream."""
i = 0
Expand Down Expand Up @@ -227,7 +233,7 @@ def _parse_dhcp_options(self, options):

class DHCPServer(object):
def __init__(self, interface, bootfile, router=None, tftp_server=None,
answer_all_requests=False, name_servers=None):
answer_all_requests=False, name_servers=None, scope=None):
self.interface = interface
self.ip, self.netmask, self.mac = get_ip_config_for_iface(interface)
self.name_servers = name_servers
Expand All @@ -240,6 +246,10 @@ def __init__(self, interface, bootfile, router=None, tftp_server=None,
self.sock = socket.socket(socket.PF_PACKET, socket.SOCK_RAW)
self.sock.bind((self.interface, ETHERNET_IP_PROTO))

if scope:
l.info('DHCP scope = ' + scope)
self.start, self.end = scope.split('-')

def serve_forever(self):
l.info('Serving PXE DHCP requests on %s' % self.interface)
while True:
Expand Down Expand Up @@ -357,28 +367,36 @@ def encode_dhcp_reply(self, request_pkt, client_ip):
return reply

def generate_free_ip(self):
server_ip = struct.unpack('!L', _pack_ip(self.ip))[0]
netmask = struct.unpack('!L', _pack_ip(self.netmask))[0]
anti_netmask = 0xFFFFFFFF - netmask

while True:
entropy = random.getrandbits(32)

client_ip = (server_ip & netmask) | (entropy & anti_netmask)

# Exclude using the server's address, the network's
# address, the broadcast address, and any IP already in
# use.
if (client_ip == server_ip or
(client_ip & netmask) == 0 or
(client_ip | netmask) == 0xFFFFFFFF):
continue

ip = _unpack_ip(struct.pack('!L', client_ip))
if ip in self.ips_allocated:
continue

return ip
# if DHCP scope set
if hasattr(self, 'start') and hasattr(self, 'end'):
possible_ips = get_ips_in_range(self.start, self.end)
for ip in self.ips_allocated:
if ip in possible_ips:
possible_ips.remove(ip)
return random.choice(possible_ips)
else:
server_ip = struct.unpack('!L', _pack_ip(self.ip))[0]
netmask = struct.unpack('!L', _pack_ip(self.netmask))[0]
anti_netmask = 0xFFFFFFFF - netmask

while True:
entropy = random.getrandbits(32)

client_ip = (server_ip & netmask) | (entropy & anti_netmask)

# Exclude using the server's address, the network's
# address, the broadcast address, and any IP already in
# use.
if (client_ip == server_ip or
(client_ip & netmask) == 0 or
(client_ip | netmask) == 0xFFFFFFFF):
continue

ip = _unpack_ip(struct.pack('!L', client_ip))
if ip in self.ips_allocated:
continue

return ip


def main():
Expand All @@ -398,6 +416,8 @@ def main():
parser.add_option("-n", "--name-servers", dest="name_servers", action='append', metavar='NAME_SERVER',
help="Domain Name Servers (DNS) IPs to provide to DHCP client. "
"Use multiple flags to specify up to 3 DNS servers", default=None)
parser.add_option("-s", "--scope", dest="scope",
help="DHCP scope, '-' separated IPs", default=None)
parser.add_option("-v", "--verbose", dest="loglevel", action="store_const",
const=logging.INFO, help="Output information messages",
default=logging.WARNING)
Expand All @@ -413,6 +433,10 @@ def main():
parser.print_help()
return 1

if options.scope and len(options.scope.split('-')) != 2:
print('Error: DHCP scope must be two dash separated IPs')
return 1

iface, bootfile = args

# Setup notification logging
Expand All @@ -423,7 +447,8 @@ def main():
try:
server = DHCPServer(iface, bootfile, router=options.router,
tftp_server=options.tftp_server,
answer_all_requests=options.answer_all_requests)
answer_all_requests=options.answer_all_requests,
scope=options.scope)
server.serve_forever()
except socket.error as e:
sys.stderr.write('Socket error (%s): %s!\n' %
Expand All @@ -432,6 +457,7 @@ def main():

return 0


if __name__ == '__main__':
try:
sys.exit(main())
Expand Down
12 changes: 9 additions & 3 deletions ptftplib/pxeserver.py
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Original file line number Diff line number Diff line change
Expand Up @@ -42,12 +42,12 @@


class DHCPThread(threading.Thread):
def __init__(self, iface, bootfile, router, answer_all_requests, name_servers):
def __init__(self, iface, bootfile, router, answer_all_requests, name_servers, scope):
threading.Thread.__init__(self)
self.setDaemon(True)
self.server = dhcpserver.DHCPServer(iface, bootfile, router=router,
answer_all_requests=answer_all_requests,
name_servers=name_servers)
name_servers=name_servers, scope=scope)

def run(self):
self.server.serve_forever()
Expand All @@ -71,6 +71,8 @@ def main():
parser.add_option("-n", "--name-servers", dest="name_servers", action='append', metavar='NAME_SERVER',
help="Domain Name Servers (DNS) IPs to provide to DHCP client. "
"Use multiple flags to specify up to 3 DNS servers", default=None)
parser.add_option("-s", "--scope", dest="scope",
help="DHCP scope, '-' separated IPs", default=None)
parser.add_option("-v", "--verbose", dest="loglevel", action="store_const",
const=logging.INFO, help="Output information messages",
default=logging.WARNING)
Expand All @@ -87,6 +89,10 @@ def main():
parser.print_help()
return 1

if options.scope and len(options.scope.split('-')) != 2:
print('Error: DHCP scope must be two dash separated IPs')
return 1

iface, root, bootfile = args

# Setup notification logging
Expand All @@ -102,7 +108,7 @@ def main():

try:
dhcp = DHCPThread(iface, bootfile, options.router, options.answer_all_requests,
options.name_servers)
options.name_servers, options.scope)
tftp = tftpserver.TFTPServer(iface, root,
strict_rfc1350=options.strict_rfc1350)
except tftpserver.TFTPServerConfigurationError as e:
Expand Down