multicast, ETOOMANYREFS and intro(2)

[Jérémie Courrèges-Anglas]

Hi,

while glancing at the multicast code I noticed the use of ETOOMANYREFS:

if (imo->imo_num_memberships == imo->imo_max_memberships) {
struct in_multi **nmships, **omships;
size_t newmax;
/*
* Resize the vector to next power-of-two minus 1. If the
* size would exceed the maximum then we know we've really
* run out of entries. Otherwise, we reallocate the vector.
*/
nmships = NULL;
omships = imo->imo_membership;
newmax = ((imo->imo_max_memberships + 1) * 2) - 1;
if (newmax <= IP_MAX_MEMBERSHIPS) {
nmships = (struct in_multi **)malloc(
sizeof(*nmships) * newmax, M_IPMOPTS,
M_NOWAIT|M_ZERO);
if (nmships != NULL) {
memcpy(nmships, omships,
sizeof(*omships) *
imo->imo_max_memberships);
free(omships, M_IPMOPTS,
sizeof(*omships) *
imo->imo_max_memberships);
imo->imo_membership = nmships;
imo->imo_max_memberships = newmax;
}
}
if (nmships == NULL) {
error = ETOOMANYREFS;
if_put(ifp);
break;
}
}

intro(2) describes it as such:

59 ETOOMANYREFS Too many references: can't splice. Not used in OpenBSD.

Obviously it *is* used, since rev. 1.1. FreeBSD and NetBSD also make
use of it, but FreeBSD doesn't document it.

I don't know whether the kernel code should keep on using it, here's
a patch to fix the documentation:

Thoughts?

Index: lib/libc/sys/intro.2
===================================================================
RCS file: /cvs/src/lib/libc/sys/intro.2,v
retrieving revision 1.62
diff -u -p -r1.62 intro.2
--- lib/libc/sys/intro.2 1 Dec 2015 01:34:16 -0000 1.62
+++ lib/libc/sys/intro.2 31 Jan 2016 00:11:06 -0000
@@ -311,8 +311,6 @@ had already been shut down with a previo
.Xr shutdown 2
call.
.It Er 59 ETOOMANYREFS Em "Too many references: can't splice" .
-Not used in
-.Ox .
.It Er 60 ETIMEDOUT Em "Operation timed out" .
A
.Xr connect 2

[Todd C. Miller]

On Mon, 01 Feb 2016 19:56:01 +0100, =?utf-8?Q?J=C3=A9r=C3=A9mie_Courr=C3=A8ges-

Post by Jérémie Courrèges-Anglas
59 ETOOMANYREFS Too many references: can't splice. Not used in OpenBSD.
Obviously it *is* used, since rev. 1.1. FreeBSD and NetBSD also make
use of it, but FreeBSD doesn't document it.
I don't know whether the kernel code should keep on using it, here's

I think the correct thing to do here is fix the documentation.

- todd

[Martin Pieuchot]

Post by Todd C. Miller
On Mon, 01 Feb 2016 19:56:01 +0100, =?utf-8?Q?J=C3=A9r=C3=A9mie_Courr=C3=A8ges-

Post by Jérémie Courrèges-Anglas
59 ETOOMANYREFS Too many references: can't splice. Not used in OpenBSD.
Obviously it *is* used, since rev. 1.1. FreeBSD and NetBSD also make
use of it, but FreeBSD doesn't document it.
I don't know whether the kernel code should keep on using it, here's

I think the correct thing to do here is fix the documentation.

We could also return ENOBUFS in this case instead. That would
correspond to the errors described in ip(4) (sadly setsockopt(2) is not
really reflecting the code).

Jérémie what other OSes report as errors for IP_ADD_MEMBERSHIP?

[Jérémie Courrèges-Anglas]

Post by Martin Pieuchot

Post by Todd C. Miller
On Mon, 01 Feb 2016 19:56:01 +0100, =?utf-8?Q?J=C3=A9r=C3=A9mie_Courr=C3=A8ges-

Post by Jérémie Courrèges-Anglas
59 ETOOMANYREFS Too many references: can't splice. Not used in OpenBSD.
Obviously it *is* used, since rev. 1.1. FreeBSD and NetBSD also make
use of it, but FreeBSD doesn't document it.
I don't know whether the kernel code should keep on using it, here's

I think the correct thing to do here is fix the documentation.

We could also return ENOBUFS in this case instead. That would
correspond to the errors described in ip(4) (sadly setsockopt(2) is not
really reflecting the code).
Jérémie what other OSes report as errors for IP_ADD_MEMBERSHIP?

I only looked at loonix-4.5-rc2 so far: ENOBUFS in this error case.

[Martin Pieuchot]

Post by Jérémie Courrèges-Anglas

Post by Martin Pieuchot

Post by Todd C. Miller
On Mon, 01 Feb 2016 19:56:01 +0100, =?utf-8?Q?J=C3=A9r=C3=A9mie_Courr=C3=A8ges-

Post by Jérémie Courrèges-Anglas
59 ETOOMANYREFS Too many references: can't splice. Not used in OpenBSD.
Obviously it *is* used, since rev. 1.1. FreeBSD and NetBSD also make
use of it, but FreeBSD doesn't document it.
I don't know whether the kernel code should keep on using it, here's

I think the correct thing to do here is fix the documentation.

We could also return ENOBUFS in this case instead. That would
correspond to the errors described in ip(4) (sadly setsockopt(2) is not
really reflecting the code).
Jérémie what other OSes report as errors for IP_ADD_MEMBERSHIP?

I only looked at loonix-4.5-rc2 so far: ENOBUFS in this error case.

Then I think it's the way to go.

[Todd C. Miller]

Post by Martin Pieuchot

Post by Jérémie Courrèges-Anglas

Post by Martin Pieuchot
We could also return ENOBUFS in this case instead. That would
correspond to the errors described in ip(4) (sadly setsockopt(2) is not
really reflecting the code).
Jérémie what other OSes report as errors for IP_ADD_MEMBERSHIP?

I only looked at loonix-4.5-rc2 so far: ENOBUFS in this error case.

Then I think it's the way to go.

Works for me.

- todd

[Jérémie Courrèges-Anglas]

Post by Todd C. Miller

Post by Martin Pieuchot

Post by Jérémie Courrèges-Anglas

Post by Martin Pieuchot
We could also return ENOBUFS in this case instead. That would
correspond to the errors described in ip(4) (sadly setsockopt(2) is not
really reflecting the code).
Jérémie what other OSes report as errors for IP_ADD_MEMBERSHIP?

I only looked at loonix-4.5-rc2 so far: ENOBUFS in this error case.

Then I think it's the way to go.

Works for me.

Hmm, FreeBSD and NetBSD still return ETOOMANYREFS in such a situation.
But the only piece of software out there that seems to actively check
for ETOOMANYREFS is D-Bus. Not relevant here since multicast isn't
involved. (https://bugs.freedesktop.org/show_bug.cgi?id=80163)

ok?

Index: sys/netinet/ip_output.c
===================================================================
RCS file: /cvs/src/sys/netinet/ip_output.c,v
retrieving revision 1.317
diff -u -p -r1.317 ip_output.c
--- sys/netinet/ip_output.c 21 Jan 2016 11:23:48 -0000 1.317
+++ sys/netinet/ip_output.c 5 Feb 2016 17:46:08 -0000
@@ -1496,7 +1496,7 @@ ip_setmoptions(int optname, struct ip_mo
}
}
if (nmships == NULL) {
- error = ETOOMANYREFS;
+ error = ENOBUFS;
if_put(ifp);
break;
}