From: Paul Donald <newtwen@gmail.com>
Date: Tue, 9 Apr 2024 03:04:05 +0000 (+0200)
Subject: router: limit prefix preferred_lt to valid_lt in accordance with RFC4861
X-Git-Url: http://git.openwrt.org/?a=commitdiff_plain;h=e164414aa18454d08bfd3d0480acfa0d5754034d;p=project%2Fodhcpd.git

router: limit prefix preferred_lt to valid_lt in accordance with RFC4861

Follow-up fix for bc9d317f2921 ("dhcpv6-ia: fix invalid preferred
lifetime").

https://www.rfc-editor.org/rfc/rfc4861#page-44

Fixes: bc9d317f2921 ("dhcpv6-ia: fix invalid preferred lifetime")
Signed-off-by: Paul Donald <newtwen@gmail.com>
Reviewed-by: Daniel Golle <daniel@makrotopia.org>
[ fix comment format and improve commit title ]
Signed-off-by: Christian Marangi <ansuelsmth@gmail.com>
---

diff --git a/src/router.c b/src/router.c
index 6eba161..b69feb3 100644
--- a/src/router.c
+++ b/src/router.c
@@ -603,6 +603,15 @@ static int send_router_advert(struct interface *iface, const struct in6_addr *fr
 				valid_lt = iface->dhcp_leasetime;
 		}
 
+		if (preferred_lt > valid_lt) {
+			/* 
+			 * RFC4861 § 6.2.1
+			 * This value [AdvPreferredLifetime] MUST NOT be larger than
+			 * AdvValidLifetime.
+			 */
+			preferred_lt = valid_lt;
+		}
+
 		if (minvalid > valid_lt)
 			minvalid = valid_lt;