[RFC][PATCH] Export DNSSL RA option to userspace

[Pierre Ossman <pierre-list@ossman.eu>]

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RFC 6106 specifies a new RA option for DNS resolver configuration that
therefore needs to end up in userspace.

This first patch just exports the new option, but I started thinking
that this seems overly complex that the kernel needs to be updated
every time there is something new of interest to userspace in the RA.
So I also have a second patch that exports everything that the kernel
doesn't want.

Patches only compile tested so far as I'm still hacking away at
userspace. Comments very much welcome though.

Rgds
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From a5b60e80eeed87763c811ecfb0d7aa5695d0a2bf Mon Sep 17 00:00:00 2001
From: Pierre Ossman <pierre@ossman.eu>
Date: Sun, 12 Dec 2010 00:06:48 +0100
Subject: [PATCH 1/2] ipv6: export DNS search list option to userspace

Like DNS resolver addresses, the suffixes to be used in DNS lookups need
to be configured by userspace. Make sure userspace has access to the
option containing that information.

Signed-off-by: Pierre Ossman <pierre@ossman.eu>
---
 include/net/ndisc.h |    3 ++-
 net/ipv6/ndisc.c    |    8 +++++++-
 2 files changed, 9 insertions(+), 2 deletions(-)

diff --git a/include/net/ndisc.h b/include/net/ndisc.h
index 895997b..9c8698a 100644
--- a/include/net/ndisc.h
+++ b/include/net/ndisc.h
@@ -33,7 +33,8 @@ enum {
 	ND_OPT_MTU = 5,			/* RFC2461 */
 	__ND_OPT_ARRAY_MAX,
 	ND_OPT_ROUTE_INFO = 24,		/* RFC4191 */
-	ND_OPT_RDNSS = 25,		/* RFC5006 */
+	ND_OPT_RDNSS = 25,		/* RFC5006 / RFC6106 */
+	ND_OPT_DNSSL = 31,		/* RFC6106 */
 	__ND_OPT_MAX
 };
 
diff --git a/net/ipv6/ndisc.c b/net/ipv6/ndisc.c
index 58841c4..c5b01e3 100644
--- a/net/ipv6/ndisc.c
+++ b/net/ipv6/ndisc.c
@@ -233,7 +233,13 @@ static struct nd_opt_hdr *ndisc_next_option(struct nd_opt_hdr *cur,
 
 static inline int ndisc_is_useropt(struct nd_opt_hdr *opt)
 {
-	return (opt->nd_opt_type == ND_OPT_RDNSS);
+	switch (opt->nd_opt_type) {
+	case ND_OPT_RDNSS:
+	case ND_OPT_DNSSL:
+		return 1;
+	default:
+		return 0;
+	}
 }
 
 static struct nd_opt_hdr *ndisc_next_useropt(struct nd_opt_hdr *cur,
-- 
1.7.2.3


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