netdev - [PATCH 3/8] ipconfig: BOOTP: Don't request IEN-116 name servers

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Message-Id: <20180417205830.1812-4-chris@chrisn.me.uk>
Date:   Tue, 17 Apr 2018 21:58:25 +0100
From:   Chris Novakovic <chris@...isn.me.uk>
To:     "David S. Miller" <davem@...emloft.net>, netdev@...r.kernel.org
Cc:     Chris Novakovic <chris@...isn.me.uk>
Subject: [PATCH 3/8] ipconfig: BOOTP: Don't request IEN-116 name servers

When ipconfig is autoconfigured via BOOTP, the request packet
initialised by ic_bootp_init_ext() allocates 8 bytes for tag 5 ("Name
Server" [1, §3.7]), but tag 5 in the response isn't processed by
ic_do_bootp_ext(). Instead, allocate the 8 bytes to tag 6 ("Domain Name
Server" [1, §3.8]), which is processed by ic_do_bootp_ext(), and appears
to have been the intended tag to request.

This won't cause any breakage for existing users, as tag 5 responses
provided by BOOTP servers weren't being processed anyway.

[1] RFC 2132, "DHCP Options and BOOTP Vendor Extensions":
    https://tools.ietf.org/rfc/rfc2132.txt

Signed-off-by: Chris Novakovic <chris@...isn.me.uk>
---
 net/ipv4/ipconfig.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/net/ipv4/ipconfig.c b/net/ipv4/ipconfig.c
index d0ea0ecc9008..bcf3c4f9882d 100644
--- a/net/ipv4/ipconfig.c
+++ b/net/ipv4/ipconfig.c
@@ -721,7 +721,7 @@ static void __init ic_bootp_init_ext(u8 *e)
 	*e++ = 3;		/* Default gateway request */
 	*e++ = 4;
 	e += 4;
-	*e++ = 5;		/* Name server request */
+	*e++ = 6;		/* (DNS) name server request */
 	*e++ = 8;
 	e += 8;
 	*e++ = 12;		/* Host name request */
-- 
2.14.1