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Mini Shell
# Copyright (C) 2012 Yahoo! Inc.
#
# Author: Joshua Harlow <harlowja@yahoo-inc.com>
#
# This file is part of cloud-init. See LICENSE file for license information.
import logging
from io import StringIO
from cloudinit import util
from cloudinit.distros.parsers import chop_comment
LOG = logging.getLogger(__name__)
# See: man resolv.conf
class ResolvConf:
def __init__(self, text):
self._text = text
self._contents = None
def parse(self):
if self._contents is None:
self._contents = self._parse(self._text)
@property
def nameservers(self):
self.parse()
return self._retr_option("nameserver")
@property
def local_domain(self):
self.parse()
dm = self._retr_option("domain")
if dm:
return dm[0]
return None
@local_domain.setter
def local_domain(self, domain):
self.parse()
self._remove_option("domain")
self._contents.append(("option", ["domain", str(domain), ""]))
return domain
@property
def search_domains(self):
self.parse()
current_sds = self._retr_option("search")
flat_sds = []
for sdlist in current_sds:
for sd in sdlist.split(None):
if sd:
flat_sds.append(sd)
return flat_sds
def __str__(self):
self.parse()
contents = StringIO()
for (line_type, components) in self._contents:
if line_type == "blank":
contents.write("\n")
elif line_type == "all_comment":
contents.write("%s\n" % (components[0]))
elif line_type == "option":
(cfg_opt, cfg_value, comment_tail) = components
line = "%s %s" % (cfg_opt, cfg_value)
if len(comment_tail):
line += comment_tail
contents.write("%s\n" % (line))
return contents.getvalue()
def _retr_option(self, opt_name):
found = []
for (line_type, components) in self._contents:
if line_type == "option":
(cfg_opt, cfg_value, _comment_tail) = components
if cfg_opt == opt_name:
found.append(cfg_value)
return found
def add_nameserver(self, ns):
self.parse()
current_ns = self._retr_option("nameserver")
new_ns = list(current_ns)
new_ns.append(str(ns))
new_ns = util.uniq_list(new_ns)
if len(new_ns) == len(current_ns):
return current_ns
self._remove_option("nameserver")
for n in new_ns:
self._contents.append(("option", ["nameserver", n, ""]))
return new_ns
def _remove_option(self, opt_name):
def remove_opt(item):
line_type, components = item
if line_type != "option":
return False
(cfg_opt, _cfg_value, _comment_tail) = components
if cfg_opt != opt_name:
return False
return True
new_contents = []
for c in self._contents:
if not remove_opt(c):
new_contents.append(c)
self._contents = new_contents
def add_search_domain(self, search_domain):
flat_sds = self.search_domains
new_sds = list(flat_sds)
new_sds.append(str(search_domain))
new_sds = util.uniq_list(new_sds)
if len(flat_sds) == len(new_sds):
return new_sds
if len(flat_sds) >= 6:
# Hard restriction on only 6 search domains
raise ValueError(
"Adding %r would go beyond the '6' maximum search domains"
% (search_domain)
)
s_list = " ".join(new_sds)
if len(s_list) > 256:
# Some hard limit on 256 chars total
raise ValueError(
"Adding %r would go beyond the "
"256 maximum search list character limit" % (search_domain)
)
self._remove_option("search")
self._contents.append(("option", ["search", s_list, ""]))
return flat_sds
def _parse(self, contents):
entries = []
for (i, line) in enumerate(contents.splitlines()):
sline = line.strip()
if not sline:
entries.append(("blank", [line]))
continue
(head, tail) = chop_comment(line, ";#")
if not len(head.strip()):
entries.append(("all_comment", [line]))
continue
if not tail:
tail = ""
try:
(cfg_opt, cfg_values) = head.split(None, 1)
except (IndexError, ValueError) as e:
raise IOError(
"Incorrectly formatted resolv.conf line %s" % (i + 1)
) from e
if cfg_opt not in [
"nameserver",
"domain",
"search",
"sortlist",
"options",
]:
raise IOError("Unexpected resolv.conf option %s" % (cfg_opt))
entries.append(("option", [cfg_opt, cfg_values, tail]))
return entries
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