From: Roy Marples <roy@marples.name>
Date: Wed, 1 Apr 2020 15:12:37 +0000 (+0100)
Subject: Note that setting pltime to zero for stale addresses isn't RFC compliant
X-Git-Tag: v9.0.0~1
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1fd4924320856c8d83d99897d0f2e3492834e576;p=thirdparty%2Fdhcpcd.git

Note that setting pltime to zero for stale addresses isn't RFC compliant

But also note we need to do this to ensure the kernel tries to use
better addresses.
---

diff --git a/src/dhcp6.c b/src/dhcp6.c
index 129d5f0e..d345b834 100644
--- a/src/dhcp6.c
+++ b/src/dhcp6.c
@@ -2416,6 +2416,9 @@ dhcp6_deprecateaddrs(struct ipv6_addrhead *addrs)
 			if (ia->prefix_vltime != 0)
 				logdebugx("%s: %s: became stale",
 				    ia->iface->name, ia->saddr);
+			/* Technically this violates RFC 8415 18.2.10.1,
+			 * but we need a mechanism to tell the kernel to
+			 * try and prefer other addresses. */
 			ia->prefix_pltime = 0;
 		} else if (ia->prefix_vltime == 0)
 			loginfox("%s: %s: no valid lifetime",
diff --git a/src/ipv6nd.c b/src/ipv6nd.c
index ba4eb8ca..2860e67c 100644
--- a/src/ipv6nd.c
+++ b/src/ipv6nd.c
@@ -1422,6 +1422,9 @@ ipv6nd_handlera(struct dhcpcd_ctx *ctx,
 			continue;
 		ipv6nd_findmarkstale(rap, ia, true);
 		logdebugx("%s: %s: became stale", ifp->name, ia->saddr);
+		/* Technically this violates RFC 4861 6.3.4,
+		 * but we need a mechanism to tell the kernel to
+		 * try and prefer other addresses. */
 		ia->prefix_pltime = 0;
 	}