Merge the resolv.conf branch in

preparation for having a new branch
for all of these changes.

3 files changed, 310 insertions, 40 deletions

diff --git a/cloudinit/distros/__init__.py b/cloudinit/distros/__init__.py
index 21efe8d9..a5d41bdb 100644
--- a/cloudinit/distros/__init__.py
+++ b/cloudinit/distros/__init__.py
@@ -33,6 +33,8 @@ from cloudinit import log as logging
 from cloudinit import ssh_util
 from cloudinit import util
 
+from cloudinit.distros import helpers
+
 LOG = logging.getLogger(__name__)
 
 
@@ -116,42 +118,43 @@ class Distro(object):
         return "127.0.0.1"
 
     def update_etc_hosts(self, hostname, fqdn):
-        # Format defined at
-        # http://unixhelp.ed.ac.uk/CGI/man-cgi?hosts
-        header = "# Added by cloud-init"
-        real_header = "%s on %s" % (header, util.time_rfc2822())
+        header = ''
+        if os.path.exists('/etc/hosts'):
+            eh = helpers.HostsConf(util.load_file("/etc/hosts"))
+        else:
+            eh = helpers.HostsConf('')
+            header = "# Added by cloud-init"
+            header = "%s on %s" % (header, util.time_rfc2822())
         local_ip = self._get_localhost_ip()
-        hosts_line = "%s\t%s %s" % (local_ip, fqdn, hostname)
-        new_etchosts = StringIO()
-        need_write = False
-        need_change = True
-        hosts_ro_fn = self._paths.join(True, "/etc/hosts")
-        for line in util.load_file(hosts_ro_fn).splitlines():
-            if line.strip().startswith(header):
-                continue
-            if not line.strip() or line.strip().startswith("#"):
-                new_etchosts.write("%s\n" % (line))
-                continue
-            split_line = [s.strip() for s in line.split()]
-            if len(split_line) < 2:
-                new_etchosts.write("%s\n" % (line))
-                continue
-            (ip, hosts) = split_line[0], split_line[1:]
-            if ip == local_ip:
-                if sorted([hostname, fqdn]) == sorted(hosts):
-                    need_change = False
-                if need_change:
-                    line = "%s\n%s" % (real_header, hosts_line)
+        prev_info = eh.get_entry(local_ip)
+        need_change = False
+        if not prev_info:
+            eh.add_entry(local_ip, fqdn, hostname)
+            need_change = True
+        else:
+            need_change = True
+            for entry in prev_info:
+                if sorted(entry) == sorted([fqdn, hostname]):
+                    # Exists already, leave it be
                     need_change = False
-                    need_write = True
-            new_etchosts.write("%s\n" % (line))
+                    break
+            if need_change:
+                # Doesn't exist, change the first
+                # entry to be this entry
+                new_entries = list(prev_info)
+                new_entries[0] = [fqdn, hostname]
+                eh.del_entries(local_ip)
+                for entry in new_entries:
+                    if len(entry) == 1:
+                        eh.add_entry(local_ip, entry[0])
+                    elif len(entry) >= 2:
+                        eh.add_entry(local_ip, *entry)
         if need_change:
-            new_etchosts.write("%s\n%s\n" % (real_header, hosts_line))
-            need_write = True
-        if need_write:
-            contents = new_etchosts.getvalue()
-            util.write_file(self._paths.join(False, "/etc/hosts"),
-                            contents, mode=0644)
+            contents = StringIO()
+            if header:
+                contents.write("%s\n" % (header))
+            contents.write("%s\n" % (eh))
+            util.write_file("/etc/hosts", contents.getvalue(), mode=0644)
 
     def _bring_up_interface(self, device_name):
         cmd = ['ifup', device_name]
diff --git a/cloudinit/distros/helpers.py b/cloudinit/distros/helpers.py
new file mode 100644
index 00000000..916935eb
--- /dev/null
+++ b/cloudinit/distros/helpers.py
@@ -0,0 +1,252 @@
+# vi: ts=4 expandtab
+#
+#    Copyright (C) 2012 Canonical Ltd.
+#    Copyright (C) 2012 Yahoo! Inc.
+#
+#    Author: Scott Moser <scott.moser@canonical.com>
+#    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
+
+
+def _chop_comment(text, comment_chars):
+    comment_locations = [text.find(c) for c in comment_chars]
+    comment_locations = [c for c in comment_locations if c != -1]
+    if not comment_locations:
+        return (text, '')
+    min_comment = min(comment_locations)
+    before_comment = text[0:min_comment]
+    comment = text[min_comment:]
+    return (before_comment, comment)
+
+
+# See: man hosts
+# or http://unixhelp.ed.ac.uk/CGI/man-cgi?hosts
+class HostsConf(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)
+
+    def get_entry(self, ip):
+        self.parse()
+        options = []
+        for (line_type, components) in self._contents:
+            if line_type == 'option':
+                (pieces, _tail) = components
+                if len(pieces) and pieces[0] == ip:
+                    options.append(pieces[1:])
+        return options
+
+    def del_entries(self, ip):
+        self.parse()
+        n_entries = []
+        for (line_type, components) in self._contents:
+            if line_type != 'option':
+                n_entries.append((line_type, components))
+                continue
+            else:
+                (pieces, _tail) = components
+                if len(pieces) and pieces[0] == ip:
+                    pass
+                elif len(pieces):
+                    n_entries.append((line_type, list(components)))
+        self._contents = n_entries
+
+    def add_entry(self, ip, canonical_hostname, *aliases):
+        self.parse()
+        self._contents.append(('option',
+                              ([ip, canonical_hostname] + list(aliases), '')))
+
+    def _parse(self, contents):
+        entries = []
+        for line in contents.splitlines():
+            if not len(line.strip()):
+                entries.append(('blank', [line]))
+                continue
+            (head, tail) = _chop_comment(line.strip(), '#')
+            if not len(head):
+                entries.append(('all_comment', [line]))
+                continue
+            entries.append(('option', [head.split(None), tail]))
+        return entries
+
+    def __str__(self):
+        self.parse()
+        contents = StringIO()
+        for (line_type, components) in self._contents:
+            if line_type == 'blank':
+                contents.write("%s\n")
+            elif line_type == 'all_comment':
+                contents.write("%s\n" % (components[0]))
+            elif line_type == 'option':
+                (pieces, tail) = components
+                pieces = [str(p) for p in pieces]
+                pieces = "\t".join(pieces)
+                contents.write("%s%s\n" % (pieces, tail))
+        return contents.getvalue()
+
+
+# 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
+
+
diff --git a/cloudinit/distros/rhel.py b/cloudinit/distros/rhel.py
index bf3c18d2..13fd5ec8 100644
--- a/cloudinit/distros/rhel.py
+++ b/cloudinit/distros/rhel.py
@@ -23,6 +23,8 @@
 import os
 
 from cloudinit import distros
+from cloudinit.distros import helpers as d_helpers
+
 from cloudinit import helpers
 from cloudinit import log as logging
 from cloudinit import util
@@ -81,16 +83,29 @@ class Distro(distros.Distro):
     def install_packages(self, pkglist):
         self.package_command('install', pkglist)
 
-    def _write_resolve(self, dns_servers, search_servers):
-        contents = []
+    def _adjust_resolve(self, dns_servers, search_servers):
+        r_conf = d_helpers.ResolvConf(util.load_file("/etc/resolv.conf"))
+        try:
+            r_conf.parse()
+        except IOError:
+            util.logexc(LOG, 
+                        "Failed at parsing %s reverting to an empty instance",
+                        "/etc/resolv.conf")
+            r_conf = d_helpers.ResolvConf('')
+            r_conf.parse()
         if dns_servers:
             for s in dns_servers:
-                contents.append("nameserver %s" % (s))
+                try:
+                    r_conf.add_nameserver(s)
+                except ValueError:
+                    util.logexc(LOG, "Failed at adding nameserver %s", s)
         if search_servers:
-            contents.append("search %s" % (" ".join(search_servers)))
-        if contents:
-            contents.insert(0, _make_header())
-            util.write_file("/etc/resolv.conf", "\n".join(contents), 0644)
+            for s in search_servers:
+                try:
+                    r_conf.add_search_domain(s)
+                except ValueError:
+                    util.logexc(LOG, "Failed at adding search domain %s", s)
+        util.write_file("/etc/resolv.conf", str(r_conf), 0644)
 
     def _write_network(self, settings):
         # TODO(harlowja) fix this... since this is the ubuntu format