[syslog-ng] [PATCH (3.4)] tfuuid: New template function to generate UUIDs.

[Balazs Scheidler]

On Mon, 2012-01-02 at 16:55 +0100, Gergely Nagy wrote:
> This patch adds a new template function: $(UUID) (also available as
> $(uuid)), which can be used to generate Universally Unique
> IDentifiers.
> 
> The use case for this is to add an UUID to each message as soon as
> they're received, so that they can be identified later, accross
> destinations. This allows me to pre-generate an ID for messages going
> into mongodb, and send those messages to a different destination too,
> with the same ID included.
> 
> Use it like this:
> 
> rewrite r_add_uuid { set("$(UUID)" value("UUID")); };
> log default { source(s_network); rewrite(r_add_uuid);
>               destination(d_mongo); destination(d_program); };

That's a great idea, see my comments on the implementation inline.

> 
> The module uses the widely available libuuid library to generate the
> UUIDs.
> 
> Signed-off-by: Gergely Nagy <algernon at balabit.hu>
> ---
>  configure.in               |   16 ++++++++++-
>  modules/Makefile.am        |    2 +-
>  modules/tfuuid/Makefile.am |   11 ++++++++
>  modules/tfuuid/tfuuid.c    |   62 ++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 89 insertions(+), 2 deletions(-)
>  create mode 100644 modules/tfuuid/Makefile.am
>  create mode 100644 modules/tfuuid/tfuuid.c
> 
> diff --git a/configure.in b/configure.in
> index 734d703..83b81ac 100644
> --- a/configure.in
> +++ b/configure.in
> +if test "x$enable_uuid" = "xyes" || test "x$enable_uuid" = "xauto"; then
> +	PKG_CHECK_MODULES(UUID, uuid, with_uuid="yes", with_uuid="no")
> +        if test "x$with_uuid" = "xno" && test "x$enable_uuid" = "xyes"; then
> +        	AC_MSG_ERROR([Could not find libuuid, and uuid support was explicitly enabled.])
> +        fi
> +        enable_uuid="$with_uuid"
> +fi
> +

If possible I'd avoid using another library, there'd a random based UUID
generator function in modules/dbparser/patternize.c

Can you check if libuuid does anything more than that?

> diff --git a/modules/tfuuid/tfuuid.c b/modules/tfuuid/tfuuid.c
> new file mode 100644
> index 0000000..c426cb8
> --- /dev/null
> +++ b/modules/tfuuid/tfuuid.c
> @@ -0,0 +1,62 @@
> +/*
> + * Copyright (c) 2012 BalaBit IT Ltd, Budapest, Hungary
> + * Copyright (c) 2012 Gergely Nagy <algernon at balabit.hu>
> + *
> + * This program is free software; you can redistribute it and/or modify it
> + * under the terms of the GNU General Public License version 2 as published
> + * by the Free Software Foundation, or (at your option) any later version.
> + *
> + * This library 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
> + * Lesser General Public License for more details.
> + *
> + * You should have received a copy of the GNU Lesser General Public
> + * License along with this library; if not, write to the Free Software
> + * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
> + */
> +
> +#include "plugin.h"
> +#include "templates.h"
> +#include "cfg.h"
> +
> +#include "config.h"
> +
> +#include <uuid/uuid.h>
> +
> +static void
> +tf_uuid(LogMessage *msg, gint argc, GString *argv[], GString *result)
> +{
> +  uuid_t uuid;
> +  gint i;
> +
> +  uuid_generate (uuid);
> +
> +  for (i = 0; i < sizeof (uuid); i++)
> +    g_string_append_printf (result, "%02x", uuid[i]);
> +}

hmm... UUID's have a well defined format (with some dashes) and I'd
prefer to use that, if the function is called $(uuid).

Here's the uuid generator function in patternize.c, could probably be
moved to the lib directory (perhaps lib/uuid.c).

I wrote that, so relicencing it to LGPL wouldn't be a problem.

static void
uuid_gen_random(gchar *buf, gsize buflen)
{
  union
  {
    struct
    {
      guint32 time_low;
      guint16 time_mid;
      guint16 time_hi_and_version;
      guint8  clk_seq_hi_res;
      guint8  clk_seq_low;
      guint8  node[6];
      guint16 node_low;
      guint32 node_hi;
    };
    guchar __rnd[16];
  } uuid;

  RAND_bytes(uuid.__rnd, sizeof(uuid));

  uuid.clk_seq_hi_res = (uuid.clk_seq_hi_res & ~0xC0) | 0x80;
  uuid.time_hi_and_version = htons((uuid.time_hi_and_version & ~0xF000) | 0x4000);

  g_snprintf(buf, buflen, "%08x-%04x-%04x-%02x%02x-%02x%02x%02x%02x%02x%02x",
                  uuid.time_low, uuid.time_mid, uuid.time_hi_and_version,
                  uuid.clk_seq_hi_res, uuid.clk_seq_low,
                  uuid.node[0], uuid.node[1], uuid.node[2],
                  uuid.node[3], uuid.node[4], uuid.node[5]);

}



> +
> +TEMPLATE_FUNCTION_SIMPLE(tf_uuid);
> +
> +static Plugin tfuuid_plugins[] =
> +  {
> +    TEMPLATE_FUNCTION_PLUGIN(tf_uuid, "UUID"),
> +    TEMPLATE_FUNCTION_PLUGIN(tf_uuid, "uuid"),
> +  };

why use two names? I'd prefer the lower case one.


-- 
Bazsi