[9front] [PATCH] ip/ipconfig: don't add default routes for ipv6 prefixes with a validlt of 0

[Arne Meyer <meyer.arne83@netcologne.de>]

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Some cpe routers announce invalidated ipv6 prefixes with a preflt and validlt of 0
for some time after they get a new prefix. the default routes for these prefixes are
getting continually removed and added with every ra we receive, so just don't bother.

At least my fritzbox behaves that way. rfc 6204 states that in this case preflt should be 0
and validlt should be 2 hours or it's current value and then counting down. But here we are.

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From: Arne Meyer <meyer.arne83@netcologne.de>
Date: Mon, 10 Jun 2024 15:45:31 +0000
Subject: [PATCH] ip/ipconfig: don't add default routes for ipv6 prefixes with a validlt of 0


at least some cpe routers announce invalidated ipv6 prefixes with a preflt and validlt of 0
for some time after they get a new prefix. the default routes for these prefixes are
getting continually removed and added with every ra we receive, so just don't bother.
---
diff 0dc37f9794c63827005b67a39a8ad749e138eda9 822a065672ccb69fd4003c6f35cc462fe4765edf
--- a/sys/src/cmd/ip/ipconfig/ipv6.c
+++ b/sys/src/cmd/ip/ipconfig/ipv6.c
@@ -725,6 +725,7 @@
 		memmove(r->hash, hash, SHA1dlen);
 
 		if(conf.routerlt == 0
+		|| conf.validlt == 0
 		|| isula(conf.laddr)
 		|| ipcmp(conf.gaddr, conf.laddr) == 0
 		|| ipcmp(conf.gaddr, conf.lladdr) == 0)