[syslog-ng] RFC5424 sending - dest=unix-stream. Framing?

Scheidler, Bal√°zs balazs.scheidler at balabit.com
Sat Feb 3 14:23:06 UTC 2018


You could use tcp(flags(syslog-protocol)) to send rfc5424 without framing.

On Feb 3, 2018 06:16, "Declan White" <declanw at is.bbc.co.uk> wrote:

> On Fri, Feb 02, 2018 at 07:01:55PM +0000, Declan White wrote:
> > Yeah, disregard me. Sorry.
> > Looks like the tunnel I'm using is unclean..
>
> Well, I fixed the tunnel, but it turned out to be a red herring. It seems
> I've got two different problems in syslog-ng (on Solaris) :
>
> 1) If I read from a unix-stream->unix-stream source, recvmsg() reliably
> EFAULT's the second read of a new connection. Unless I attach a library
> call tracer.. and then it won't. Heisenbug...
>         10109/11:       write(2, 0x00059898, 58)                        =
> 58
>         10109/11:          S e t t i n g   v a l u e ;   m s g = ' 4 7 b 1
> 0 ' ,   n a m e
>         10109/11:          = ' S O U R C E ' ,   v a l u e = ' i n _ t e s
> t '
>         10109/11:       write(2, "\n", 1)                               = 1
>         10109/11:       recvmsg(15, 0xFE66B4B4, 0)
> Err#14 EFAULT
>
> I think my build env may have eaten something bad. I'm recompiling all the
> dependant libs with GCC, and dumping libwrap, to see if that changes
> anything.
>
> Is any of this compiler noise relevant? :
>         ../source/syslog-ng-3.12.1/modules/afsocket/socket-options-inet.c:47:8:
> warning: unused variable 'on' [-Wunused-variable]
>            gint on = 1;
>         ../source/syslog-ng-3.12.1/modules/afsocket/transport-unix-socket.c:52:35:
> warning: format '%d' expects argument of type 'int', but argument 4 has
> type 'pid_t {aka long int}' [-Wformat=]
>            g_snprintf(buf, buflen, "/proc/%d/%s", pid, proc_file);
>         ../source/syslog-ng-3.12.1/modules/afsocket/transport-unix-socket.c:138:1:
> warning: '_add_nv_pair_proc_readlink' defined but not used
> [-Wunused-function]
>         ../source/syslog-ng-3.12.1/modules/afsocket/transport-unix-socket.c:118:1:
> warning: '_add_nv_pair_proc_read_argv' defined but not used
> [-Wunused-function
>         ../source/syslog-ng-3.12.1/modules/afsocket/transport-unix-socket.c:104:1:
> warning: '_add_nv_pair_proc_read_unless_unset' defined but not used
> [-Wunused-function]
>         ../source/syslog-ng-3.12.1/modules/afsocket/transport-unix-socket.c:38:1:
> warning: '_add_nv_pair_int' defined but not used [-Wunused-function]
>         ../source/syslog-ng-3.12.1/modules/afstreams/afstreams.c: In
> function 'log_transport_streams_new':
>         ../source/syslog-ng-3.12.1/modules/afstreams/afstreams.c:97:14:
> warning: assignment from incompatible pointer type
> [-Wincompatible-pointer-types]
>            self->read = log_transport_streams_read;
>         ../source/syslog-ng-3.12.1/modules/afstreams/afstreams.c: In
> function 'afstreams_init_door':
>         ../source/syslog-ng-3.12.1/modules/afstreams/afstreams.c:133:11:
> warning: implicit declaration of function 'close'; did you mean 'pclose'?
> [-Wimplicit-function-declaration]
>                    close(fd);
>
> 2) If I avoid that unix-stream source and socat the client from a unix
> domain socket destination into a syslog port source, syslog-ng now has a
> mismatch of a source sending no framing, and a destination expecting it.
>
> syslog()
>         write(5, 0x000721E8, 60)                        = 60
>            5 7   < 1 3 > 1   2 0 1 8 - 0 2 - 0 3 T 0 3 : 1 1 : 2 0 + 0 0 :
>            0 0   o p s t e s t 6 a   -   -   -   -   t e s t 0 8\n
>
> unix-stream()
>         read(6, 0x00072B00, 8192)                       = 57
>            < 1 3 > 1   2 0 1 8 - 0 2 - 0 3 T 0 2 : 0 5 : 0 5 + 0 0 : 0 0
>            o p s t e s t 6 a   -   -   -   -   t e s t 0 7\n
>
> I take it that if I did something evil like faking up a length header with
> length() in a template() I might get unix-stream -> syslog working?
>
>
> > On Fri, Feb 02, 2018 at 06:48:09AM +0100, Scheidler, Bal?zs wrote:
> > > If the new lines at the end are ok, and the messages dont contain
> newlines
> > > themselves, you should be fine. If both destination and source is
> > > unix-STREAM(). Don't you hapoen to use unix-dgram() somewhere? That
> would
> > > take the datagram fragments as individual messages.
> > >
> > > Can you show me the framing errors you mention?
> > >
> > >
> > > On Feb 1, 2018 22:33, "Declan White" <declanw at is.bbc.co.uk> wrote:
> > >
> > > I have syslog-ng pumping data into a unix-stream destination
> > > socketfilething.
> > >
> > > Data going into this domain socket has lots of adventures, and then
> emerges
> > > as a source unix-stream on another host.
> > > Both have flags(syslog-protocol), but the data gets framing errors at
> the
> > > receiver.
> > >
> > > I think it's become a bytestream (instead of a message stream)
> enroute, and
> > > the recv() is relying on only getting one message at a time, because it
> > > can't know the message length any other way, as unix-stream gets
> messages
> > > without framing(?).
> > >
> > > Is there a way to salvage this? (I noticed TLS might add framing, but
> since
> > > the tunnel is already TLS ...)
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