[.joined/src/trunk]: .joined/src/sys/net sys/net: Document if_mcast_op with c...

[riastradh <riastradh%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/.joined/src/rev/661076791f2d
branches:  trunk
changeset: 359348:661076791f2d
user:      riastradh <riastradh%NetBSD.org@localhost>
date:      Fri Dec 31 14:26:29 2021 +0000

description:
sys/net: Document if_mcast_op with comment and refuse other commands.

Meant only for multicast addition/deletion operations, nothing else.

diffstat:

 sys/net/if.c |  23 +++++++++++++++++++++--
 1 files changed, 21 insertions(+), 2 deletions(-)

diffs (50 lines):

diff -r edf17e2033ea -r 661076791f2d sys/net/if.c
--- a/sys/net/if.c      Fri Dec 31 14:26:19 2021 +0000
+++ b/sys/net/if.c      Fri Dec 31 14:26:29 2021 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: if.c,v 1.500 2021/12/31 14:26:19 riastradh Exp $       */
+/*     $NetBSD: if.c,v 1.501 2021/12/31 14:26:29 riastradh Exp $       */
 
 /*-
  * Copyright (c) 1999, 2000, 2001, 2008 The NetBSD Foundation, Inc.
@@ -90,7 +90,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.500 2021/12/31 14:26:19 riastradh Exp $");
+__KERNEL_RCSID(0, "$NetBSD: if.c,v 1.501 2021/12/31 14:26:29 riastradh Exp $");
 
 #if defined(_KERNEL_OPT)
 #include "opt_inet.h"
@@ -3879,12 +3879,31 @@
        return rc;
 }
 
+/*
+ * if_mcast_op(ifp, cmd, sa)
+ *
+ *     Apply a multicast command, SIOCADDMULTI/SIOCDELMULTI, to the
+ *     interface.  Returns 0 on success, nonzero errno(3) number on
+ *     failure.
+ *
+ *     May sleep.
+ *
+ *     Use this, not if_ioctl, for the multicast commands.
+ */
 int
 if_mcast_op(ifnet_t *ifp, const unsigned long cmd, const struct sockaddr *sa)
 {
        int rc;
        struct ifreq ifr;
 
+       switch (cmd) {
+       case SIOCADDMULTI:
+       case SIOCDELMULTI:
+               break;
+       default:
+               panic("invalid ifnet multicast command: 0x%lx", cmd);
+       }
+
        ifreq_setaddr(cmd, &ifr, sa);
        rc = if_ioctl(ifp, cmd, &ifr);