"""
Configuration file output for the ISC DHCP server
"""
import conf
import itertools
class ConfDHCP (conf.File) :
def __init__ (self, name="dhcpd.conf", path="/etc/dhcp3/dhcpd.conf") :
"""
Initialize the dhcpd config file, but don't open it yet
@see conf.ConfFile.__init__
"""
super(ConfDHCP, self).__init__(name, path)
class Statement (conf.Object) :
"""
A statement is a single line in the config file
"""
def __init__ (self, name, *args) :
"""
The statement will be formatted like this:
<name> [ <arg> [ ... ] ] ";"
"""
self.name = name
self.args = args
def _fmt_arg (self, arg) :
"""
Formats a arg for use in output, the following types are supported:
list/tuple/iter: results in a comma-and-space separated list of formatted values
unicode: results in an encoded str
str: results in the string itself, quoted if needed
other: attempt to convert to a str, and then format that
"""
# format lists specially
# XXX: iterators?
if isinstance(arg, (list, tuple)) :
# recurse as a comma-and-space separated list
return ', '.join(self._fmt_arg(a) for a in arg)
elif isinstance(arg, Literal) :
# use what it specifies
return arg.fmt_arg()
elif isinstance(arg, unicode) :
# recurse with the str version
# XXX: what encoding to use?
return self._fmt_arg(arg.encode('utf8'))
elif isinstance(arg, str) :
# XXX: quoting
return arg
else :
# try and use it as a string
return self._fmt_arg(str(arg))
def _fmt_data (self) :
"""
Formats the statement name/params as a single line
"""
return "%s%s" % (self.name, (' ' + ' '.join(self._fmt_arg(a) for a in self.args)) if self.args else '')
class Literal (Statement) :
"""
A literal is something that goes into the config file as-is, with no formatting or escaping applied.
"""
def __init__ (self, literal) :
self.literal = literal
def fmt_arg (self) :
return self.literal
def fmt_lines (self) :
yield self.literal
class Parameter (Statement) :
"""
A parameter is a single statement that configures the behaviour of something.
Parameters have a name, and optionally, a number of arguments, and are formatted as statements terminated with
a semicolon.
"""
def fmt_lines (self) :
"""
Yields a single ;-terminated line
"""
yield "%s;" % self._fmt_data()
class Declaration (Statement) :
"""
A declaration begins like a statement (with name and args), but then contains a block of any number of
parameters followed by any number of nested declarations.
<name> [ <args> [ ... ] ] {
[ <parameters> ]
[ <declarations> ]
}
"""
def __init__ (self, name, args=[], params=[], decls=[]) :
"""
The name/args will be formatted as in Statement, but params should be an iterable of Parameters, and decls
an iterable of Declarations.
"""
# init the statement bit
Statement.__init__(self, name, *args)
# store the iterables
self.params = params
self.decls = decls
def fmt_lines (self) :
"""
Yields a header line, a series of indented body lines, and the footer line
"""
# the header to open the block
yield "%s {" % self._fmt_data()
# then output each content line
for stmt in itertools.chain(self.params, self.decls) :
# ..indented
for line in stmt.fmt_lines() :
yield "\t%s" % line
# and then close the block
yield "}"
class SharedNetwork (Declaration) :
"""
A shared-network declaration is used to define a set of subnets that share the same physical network,
optionally with some shared params.
shared-network <name> {
[ parameters ]
[ declarations ]
}
"""
def __init__ (self, name, params=[], decls=[]) :
"""
@param name the name of the shared-subnet
@param params optional parameters
@param decls the iterable of subnets or other declarations in the shared network
"""
super(SharedNetwork, self).__init__("shared-network", [name], params, decls)
class Subnet (Declaration) :
"""
A subnet is used to provide the information about a subnet required to identify whether or not an IP address is
on that subnet, and may also be used to specify parameters/declarations for that subnet.
subnet <subnet-number> netmask <netmask> {
[ parameters ]
[ declarations ]
}
"""
def __init__ (self, network, params=[], decls=[]) :
"""
@param network the addr.Network for the subnet
@param params optional parameters
@param decls optional decls, e.g. subnets
"""
super(Subnet, self).__init__("subnet", [network.net(), "netmask", network.netmask()], params, decls)
class Group (Declaration) :
"""
A group is simply used to apply a set of parameters to a set of declarations.
group {
[ parameters ]
[ declarations ]
}
"""
def __init__ (self, params=[], decls=[]) :
super(Group, self).__init__("group", [], params, decls)
class Host (Declaration) :
"""
A host is used to match a request against specific host, and then apply settings for that host.
The "hostname" is the DHCP name to identify the host.
If no dhcp-client-identifier option is specified in the parameters, then the host is matched using the
"hardware" parameter.
host <hostname> {
[ parameters ]
[ declarations ]
}
"""
def __init__ (self, hostname, params=[], decls=[]) :
super(Host, self).__init__("host", [hostname], params, decls)
class Option (Parameter) :
"""
A generic 'option' parameter for a dhcpd.conf file
"""
def __init__ (self, name, *args) :
"""
Formatted as a Satement with a name of "option <name>".
"""
super(Option, self).__init__("option %s" % name, *args)