diff options
Diffstat (limited to 'cloudinit/distros/parsers/resolv_conf.py')
| -rw-r--r-- | cloudinit/distros/parsers/resolv_conf.py | 169 |
1 files changed, 169 insertions, 0 deletions
diff --git a/cloudinit/distros/parsers/resolv_conf.py b/cloudinit/distros/parsers/resolv_conf.py new file mode 100644 index 00000000..5733c25a --- /dev/null +++ b/cloudinit/distros/parsers/resolv_conf.py @@ -0,0 +1,169 @@ +# vi: ts=4 expandtab +# +# Copyright (C) 2012 Yahoo! Inc. +# +# Author: Joshua Harlow <harlowja@yahoo-inc.com> +# +# This program is free software: you can redistribute it and/or modify +# it under the terms of the GNU General Public License version 3, as +# published by the Free Software Foundation. +# +# This program is distributed in the hope that it will be useful, +# but WITHOUT ANY WARRANTY; without even the implied warranty of +# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the +# GNU General Public License for more details. +# +# You should have received a copy of the GNU General Public License +# along with this program. If not, see <http://www.gnu.org/licenses/>. + +from StringIO import StringIO + +from cloudinit import util + +from cloudinit.distros.parsers import chop_comment + + +# See: man resolv.conf +class ResolvConf(object): + 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 + + @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 + if len(current_ns) >= 3: + # Hard restriction on only 3 name servers + raise ValueError(("Adding %r would go beyond the " + "'3' maximum name servers") % (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 + + @local_domain.setter + def local_domain(self, domain): + self.parse() + self._remove_option('domain') + self._contents.append(('option', ['domain', str(domain), ''])) + return domain + + 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): + raise IOError("Incorrectly formatted resolv.conf line %s" + % (i + 1)) + 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 |