LOCAL_CREDS socket option
Maxim Konovalov
maxim at macomnet.ru
Fri Mar 16 12:56:16 UTC 2007
On Fri, 16 Mar 2007, 13:47+0100, Hartmut Brandt wrote:
> Maxim Konovalov wrote:
> > On Fri, 16 Mar 2007, 10:51+0100, Harti Brandt wrote:
> >
> >
> > > Hi,
> > >
> > > is there any specific reason that we don't support the LOCAL_CREDS
> > > option for SOCK_DGRAM sockets in the local domain? It's documented
> > > in unix(4) for a long time and it looks like it is supported, for
> > > example, in NetBSD.
> > >
> >
> > IIRC it is supported.
> >
> > From tools/regression/sockets/unix_cmsg/README:
> >
> > For SOCK_DGRAM sockets:
> > ----------------------
> > [...]
> > 3: Sending cmsgcred, receiving sockcred
> >
> > Server creates datagram socket and set socket option LOCAL_CREDS
> > for it. Client sends one message with data and control message with
> > SOCK_CREDS type to Server. Server should receive one message with
> > data and control message with SCM_CREDS type followed by struct
> > sockcred{} and this structure should contain correct information.
> >
> >
> Well, this comment does not actually mean, that the feature works - it just
> means that the regression test tests it. If you look at uipc_usrreq.c:
>
> static struct protosw localsw[] = {
> {
> .pr_type = SOCK_STREAM,
> .pr_domain = &localdomain,
> .pr_flags = PR_CONNREQUIRED|PR_WANTRCVD|PR_RIGHTS,
> .pr_ctloutput = &uipc_ctloutput,
> .pr_usrreqs = &uipc_usrreqs
> },
> {
> .pr_type = SOCK_DGRAM,
> .pr_domain = &localdomain,
> .pr_flags = PR_ATOMIC|PR_ADDR|PR_RIGHTS,
> .pr_usrreqs = &uipc_usrreqs
> },
>
> you see that .pr_ctloutput is NULL for SOCK_DGRAM sockets which
> means they don't support any of the socket options described in
> unix(4). Also I included that feature into bsnmp(1) where I found
> out that it doesn't work. I've a patch to fix it, but wanted to know
> whether it was left out on purpose or not.
You are correct, it fails.
SERVER: setsockopt(LOCAL_CREDS) for datagram socket: Protocol not available
3: Sending cmsgcred, receiving sockcred
--
Maxim Konovalov
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