From: Paul Donald <newtwen+github@gmail.com>
Date: Fri, 3 Oct 2025 14:33:49 +0000 (+0200)
Subject: router: Apply updated values from RFC9096 (updates RFC4861) to RA/ND
X-Git-Url: http://git.openwrt.org/?a=commitdiff_plain;h=dc03e02d973ed2f6f4efdd67d6795dd30a88a164;p=project%2Fodhcpd.git

router: Apply updated values from RFC9096 (updates RFC4861) to RA/ND

https://datatracker.ietf.org/doc/html/rfc9096#section-3.4

Signed-off-by: Paul Donald <newtwen+github@gmail.com>
Link: https://github.com/openwrt/odhcpd/pull/225
Signed-off-by: Álvaro Fernández Rojas <noltari@gmail.com>
---

diff --git a/src/router.h b/src/router.h
index 19b0079..6609f43 100644
--- a/src/router.h
+++ b/src/router.h
@@ -54,7 +54,18 @@ struct icmpv6_opt {
 
 	Note: this is 16 bit Router Lifetime field in RA packets
 */
-#define RouterLifetime					65535
+/* RFC9096 defines recommended option lifetimes configuration values
+	ND_PREFERRED_LIMIT 2700
+	ND_VALID_LIMIT 5400
+
+	RFC9096  §3.4
+	CE routers SHOULD set the "Router Lifetime" of Router Advertisement
+	(RA) messages to ND_PREFERRED_LIMIT.
+
+	Note: while the RFC recommends SHOULD of ND_PREFERRED_LIMIT, this
+	define is used to cap values to a sane ceiling, i.e. ND_VALID_LIMIT.
+*/
+#define RouterLifetime					5400
 
 #define ND_RA_FLAG_PROXY		0x4
 #define ND_RA_PREF_HIGH			(1 << 3)