This fixes the problem reported in:

  https://bugzilla.redhat.com/show_bug.cgi?id=868389

Previously, the dnsmasq hosts file (used for static dhcp entries, and
addnhosts file (used for additional dns host entries) were only
created/referenced on the dnsmasq commandline if there was something
to put in them at the time the network was started. Once we can update
a network definition while it's active (which is now possible with
virNetworkUpdate), this is no longer a valid strategy - if there were
0 dhcp static hosts (resulting in no reference to the hosts file on the
commandline), then one was later added, the commandline wouldn't have
linked dnsmasq up to the file, so even though we create it, dnsmasq
doesn't pay any attention.

The solution is to just always create these files and reference them
on the dnsmasq commandline (almost always, anyway). That way dnsmasq
can notice when a new entry is added at runtime (a SIGHUP is sent to
dnsmasq by virNetworkUdpate whenever a host entry is added or removed)

The exception to this is that the dhcp static hosts file isn't created
if there are no lease ranges *and* no static hosts. This is because in
this case dnsmasq won't be setup to listen for dhcp requests anyway -
in that case, if the count of dhcp hosts goes from 0 to 1, dnsmasq
will need to be restarted anyway (to get it listening on the dhcp
port). Likewise, if the dhcp hosts count goes from 1 to 0 (and there
are no dhcp ranges) we need to restart dnsmasq so that it will stop
listening on port 67. These special situations are handled in the
bridge driver's networkUpdate() by checking for ((bool)
nranges||nhosts) both before and after the update, and triggering a
dnsmasq restart if the before and after don't match.

This patch removed the "--filterwin2k" dnsmasq command line
parameter which was unnecessary for domain specification,
possibly blocked some usage, and was command line clutter.

Gene Czarcinski <gene@czarc.net>

Without this patch, logged command executions can be ambiguous if
the command contained any shell metacharacters.  This has caused
more than one person to attempt to patch clients to add unnecessary
quoting, without realizing that the command itself was run with
correct args, and only the logged output was ambiguous.

* src/util/command.c (virCommandToString): Add shell escapes.
* tests/commandtest.c (test16): Test new behavior.
* tests/commanddata/test16.log: Update expected output.
* tests/qemuxml2argvdata/qemuxml2argv-*.args: Likewise.
* tests/networkxml2argvdata/*.argv: Likewise.

dnsmasq is forwarding a number of queries upstream that should not
be done.  There still remains an MX query for a plain name with no
domain specified that will be forwarded is dnsmasq has --domain=xxx
--local=/xxx/ specified. This does not happen with no domain name
and --local=// ... not a libvirt problem.

BTW, thanks again to Claudio Bley!

The path to the dnsmasq binary can be configured while in the test data
the path is hard-coded to /usr/bin/. This break the test suite if a the
binary is located in a different location, like /usr/local/sbin/.

Replace the hard coded path in the test data by a token, which is
dynamically replaced in networkxml2argvtest with the configured path
after the test data has been loaded.

(Another option would have been to modify configure.ac to generate the
 test data during configure, but I do not know of an easy way do trick
 configure into mass-generate those test files without listing every
 single one, which I consider less flexible.)

- unit-test the unit-test:
  #include <assert.h>
  #define TEST(in,token,rep,out) { char *buf = strdup(in); assert(!replaceTokens(&buf, token, rep) && !strcmp(buf, out)); free(buf); }
  TEST("", "AA", "B", "");
  TEST("A", "AA", "B", "A");
  TEST("AA", "AA", "B", "B");
  TEST("AAA", "AA", "B", "BA");
  TEST("AA", "AA", "BB", "BB");
  TEST("AA", "AA", "BBB", "BBB");
  TEST("<AA", "AA", "B", "<B");
  TEST("<AA", "AA", "BB", "<BB");
  TEST("<AA", "AA", "BBB", "<BBB");
  TEST("AA>", "AA", "B", "B>");
  TEST("AA>", "AA", "BB", "BB>");
  TEST("AA>", "AA", "BBB", "BBB>");
  TEST("<AA>", "AA", "B", "<B>");
  TEST("<AA>", "AA", "BB", "<BB>");
  TEST("<AA>", "AA", "BBB", "<BBB>");
  TEST("<AA|AA>", "AA", "B", "<B|B>");
  TEST("<AA|AA>", "AA", "BB", "<BB|BB>");
  TEST("<AA|AA>", "AA", "BBB", "<BBB|BBB>");
  TEST("<AAAA>", "AA", "B", "<BB>");
  TEST("<AAAA>", "AA", "BB", "<BBBB>");
  TEST("<AAAA>", "AA", "BBB", "<BBBBBB>");
  TEST("AAAA>", "AA", "B", "BB>");
  TEST("AAAA>", "AA", "BB", "BBBB>");
  TEST("AAAA>", "AA", "BBB", "BBBBBB>");
  TEST("<AAAA", "AA", "B", "<BB");
  TEST("<AAAA", "AA", "BB", "<BBBB");
  TEST("<AAAA", "AA", "BBB", "<BBBBBB");
  alarm(1); /* no infinite loop */
  TEST("A", "A", "A", "A");
  TEST("AA", "A", "A", "AA");
  alarm(0);
Signed-off-by: NPhilipp Hahn <hahn@univention.de>

Hi,
this is the fifth version of my SRV record for DNSMasq patch rebased
for the current codebase to the bridge driver and libvirt XML file to
include support for the SRV records in the DNS. The syntax is based on
DNSMasq man page and tests for both xml2xml and xml2argv were added as
well. There are some things written a better way in comparison with
version 4, mainly there's no hack in tests/networkxml2argvtest.c and
also the xPath context is changed to use a simpler query using the
virXPathInt() function relative to the current node.

Also, the patch is also fixing the networkxml2argv test to pass both
checks, i.e. both unit tests and also syntax check.

Please review,
Michal
Signed-off-by: NMichal Novotny <minovotn@redhat.com>

This is in response to:

  https://bugzilla.redhat.com/show_bug.cgi?id=723862

which points out that a guest on an "isolated" network could
potentially exploit the DNS forwarding provided by dnsmasq to create a
communication channel to the outside.

This patch eliminates that possibility by adding the "--no-resolv"
argument to the dnsmasq commandline, which tells dnsmasq to not
forward on any requests that it can't resolve itself (by looking at
its own static hosts files and runtime list of dhcp clients), but to
instead return a failure for those requests.

This shouldn't cause any undesirable change from current
behavior, even in the case where a guest is currently configured with
multiple interfaces, one of them being connected to an isolated
network, and another to a network that does have connectivity to the
outside. If the isolated network's DNS server is queried for a name
it doesn't know, it will return "Refused" rather than "Unknown", which
indicates to the guest that it should query other servers, so it then
queries the connected DNS server, and gets the desired response.

networkSaveDnsmasqHostsfile was added in 8fa9c221 (Apr 2010).
It has a force flag. If the dnsmasq hostsfile already exists force
needs to be true to overwrite it. networkBuildDnsmasqArgv sets force
to false, networkDefine sets it to true. This results in the
hostsfile being written only in networkDefine in the common case.
If no error occurred networkSaveDnsmasqHostsfile returns true and
networkBuildDnsmasqArgv adds the --dhcp-hostsfile to the dnsmasq
command line.

networkSaveDnsmasqHostsfile was changed in 89ae9849 (24 Jun 2011)
to return a new dnsmasqContext instead of reusing one. This change broke
the logic of the force flag as now networkSaveDnsmasqHostsfile returns
NULL on error, but the early return -- if force was not set and the
hostsfile exists -- returns 0. This turned the early return in an error
case and networkBuildDnsmasqArgv didn't add the --dhcp-hostsfile option
anymore if the hostsfile already exists. It did because networkDefine
created the hostsfile already.

Then 9d4e2845 fixed the return 0 case in networkSaveDnsmasqHostsfile
but didn't apply the force option correctly to the new addnhosts file.
Now force doesn't control an early return anymore, but influences the
handling of the hostsfile context creation and dnsmasqSave is always
called now. This commit also added test cases that reveal several
problems. First, the tests now calls functions that try to write the
dnsmasq config files to disk. If someone runs this tests as root this
might overwrite actively used dnsmasq config files, this is a no-go. Also
the tests depend on configure --localstatedir, this needs to be fixed as
well, because it makes the tests fail when localstatedir is different
from /var.

This patch does several things to fix this:

1) Move dnsmasqContext creation and saving out of networkBuildDnsmasqArgv
to the caller to separate the command line generation from the config
file writing. This makes the command line generation testable without the
risk of interfering with system files, because the tests just don't call
dnsmasqSave.

2) This refactoring of networkSaveDnsmasqHostsfile makes the force flag
useless as the saving happens somewhere else now. This fixes the wrong
usage of the force flag in combination with then newly added addnhosts
file by removing the force flag.

3) Adapt the wrong test cases to the correct behavior, by adding the
missing --dhcp-hostsfile option. Both affected tests contain DHCP host
elements but missed the necessary --dhcp-hostsfile option.

4) Rename networkSaveDnsmasqHostsfile to networkBuildDnsmasqHostsfile,
because it doesn't save the dnsmasqContext anymore.

5) Move all directory creations in dnsmasq context handling code from
the *New functions to dnsmasqSave to avoid directory creations in system
paths in the test cases.

6) Now that networkBuildDnsmasqArgv doesn't create the dnsmasqContext
anymore the test case can create one with the localstatedir that is
expected by the tests instead of the configure --localstatedir given one.

If a domain name is defined for a network, add the --expand-hosts
option to the dnsmasq commandline. This results in the domain being
added to any hostname that is defined in a dns <host> element and
contains no '.' characters (i.e. it is an "unqualified"
hostname). Since PTR records are automatically created for any name
defined in <host>, the result of a PTR request will change from the
unqualified name to the qualified name.

This also has the same effect on any hostnames that dnsmasq reads
from the host's /etc/hosts file.

(In the case of guest hostnames that were learned by dnsmasq via DHCP
requests, they were already getting the domain name added on, even
without --expand-hosts).

'make syntax-check' regression introduced in commit 60b9c693.

* tests/networkxml2argvdata/*.argv: Break long lines.

This commit introduces names definition for the DNS hosts file using
the following syntax:

  <dns>
    <host ip="192.168.1.1">
      <name>alias1</name>
      <name>alias2</name>
    </host>
  </dns>

Some of the improvements and fixes were done by Laine Stump so
I'm putting him into the SOB clause again ;-)
Signed-off-by: NMichal Novotny <minovotn@redhat.com>
Signed-off-by: NLaine Stump <laine@laine.org>

The regression testing done by comparison of command-line
generated from the network XML file and the expected
command-line arguments (read from file).
Signed-off-by: NMichal Novotny <minovotn@redhat.com>