We either use the value from the environment variable, or learn it from
the existing lease file.

In the second case, the pointer would be pointing into the JSON object
of the first lease with a DUID, owned by leases_array, then
leases_array_new.

Always allocate the string instead, making obvious who should free the
string.

If dnsmasq specified DNSMASQ_IAID (so we're dealing with an IPv6
lease) but no DNSMASQ_MAC, we skip creation of the new lease object.

Also skip adding it to the leases array.

https://bugzilla.redhat.com/show_bug.cgi?id=1202350

Introduced in ca6dbdd0

Coverity pointed out that in other places we always check the return
value from virJSONValueObjectGetNumberLong() but not in the new addition
in leaseshelper. To solve the issue and also be more robust in case
somebody would corrupt the file, skip outputting of the lease entry in
case the expiry time is missing.

Untangle a few conditions into a case statement and improve reporting of
invaid commands.

This patch enables the helper program to detect event(s) triggered when
there is a change in lease length or expiry and client-id. This
transfers complete control of leases database to libvirt and obsoletes
use of the lease database file (<network-name>.leases). That file will
not be created, read, or written.  This is achieved by adding the option
--leasefile-ro to dnsmasq and passing a custom env var to leaseshelper,
which helps us map events related to leases with their corresponding
network bridges, no matter what the event be.

Also, this requires the addition of a new non-lease entry in our custom
lease database: "server-duid". It is required to identify a DHCPv6
server.

Now that dnsmasq doesn't maintain its own leases database, it relies on
our helper program to tell it about previous leases and server duid.
Thus, this patch makes our leases program honor an extra action: "init",
in which it sends the known info in a particular format to dnsmasq
by printing it to stdout.

The drawback of this change is that upgrade to this new approach does
not transfer the existing leases for the network if the leaseshelper
wasn't already used.

If the VIR_STRDUP(exptime,...) fails, then we will jump to cleanup,
no need to check if exptime is set which causes Coverity to issue
a complaint in the virStrToLong_ll call because there wasn't a check
for a NULL value while there was one for the reference right after
the VIR_STRDUP().
Signed-off-by: NJohn Ferlan <jferlan@redhat.com>

Contents of existing lease file were being stored in a variable
which was never freed.

When copying entries from the old lease file into the new array the old
code would copy the pointer of the json object into the second array
without removing it from the first. Afterwards when both arrays were
freed this might lead to a crash due to access of already freed memory.

Refactor the code to use the new array item stealing helper added to the
json code so that the entry resides just in one array.

Instead of reporting an error and terminating, rewrite the file with
the newly learned info.

The value is provided via environment and causes a crash if not defined.

We create a 'lease_new' when we are adding new lease entry, then later
in the code we add the 'lease_new' into a 'leases_array_new' which
leads into the crash because we double free the 'lease_new'.

To prevent the double free we set the 'lease_new' to NULL after
successful append into the 'leases_array_new'.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

Commit baafe668 introduced new leaseshelper with a crash of freeing
env string. Calling 'getenv()' inside 'virGetEnvAllowSUID()' may
return a static string and we definitely should not free it.

The author probably want to free the copy of that string.
Signed-off-by: NPavel Hrdina <phrdina@redhat.com>

On freebsd there isn't known "setlocale" so we have to include locale.h

Introduce helper program to catch events from dnsmasq and maintain a custom
lease file per network. It supports dhcpv4 and dhcpv6. The file is saved as
"<interface-name>.status".

Each lease contains the following info:
<expiry-time (epoch time)> <mac> <iaid> <ip-address> <hostname> <clientid>

Example of custom leases file content:
[
    {
        "iaid": "1221229",
        "ip-address": "2001:db8:ca2:2:1::95",
        "mac-address": "52:54:00:12:a2:6d",
        "hostname": "Fedora20",
        "client-id": "00:04:1a:c1:d9:6b:5a:0a:e2:bc:f8:4b:1e:37:2e:38:22:55",
        "expiry-time": 1393244216
    },
    {
        "ip-address": "192.168.150.208",
        "mac-address": "52:54:00:11:56:b3",
        "hostname": "Wani-PC",
        "client-id": "01:52:54:00:11:56:b3",
        "expiry-time": 1393244248
    }
]

src/Makefile.am:
   * Add options to compile the helper program

src/network/bridge_driver.c:
   * Introduce networkDnsmasqLeaseFileNameCustom()
   * Invoke helper program along with dnsmasq
   * Delete the .status file when corresponding n/w is destroyed.

src/network/leaseshelper.c
   * Helper program to create the custom lease file