From: Roy Marples <roy@marples.name>
Date: Fri, 15 May 2015 14:32:54 +0000 (+0000)
Subject: For now, ignore ND DNS lifetimes unless they are absent or zero, in
X-Git-Tag: v6.9.0~14
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=0c049a01de2fee448f5e27a72f572f6c425b24cb;p=thirdparty%2Fdhcpcd.git

For now, ignore ND DNS lifetimes unless they are absent or zero, in
which case they are removed from consideration.
---

diff --git a/dhcpcd-hooks/20-resolv.conf b/dhcpcd-hooks/20-resolv.conf
index e010ab7c..d99cc7fa 100644
--- a/dhcpcd-hooks/20-resolv.conf
+++ b/dhcpcd-hooks/20-resolv.conf
@@ -68,31 +68,51 @@ build_resolv_conf()
 	rm -f "$cf"
 }
 
+# Extract any ND DNS options from the RA
+# For now, we ignore the lifetime of the DNS options unless they
+# are absent or zero.
+# In this case they are removed from consideration.
+# See draft-gont-6man-slaac-dns-config-issues-01 for issues
+# regarding DNS option lifetime in ND messages.
+eval_nd_dns()
+{
+
+	eval ltime=\$nd${i}_rdnss${j}_lifetime
+	if [ -z "$ltime" -o "$ltime" = 0 ]; then
+		rdnss=
+	else
+		eval rdnss=\$nd${i}_rdnss${j}_servers
+	fi
+	eval ltime=\$nd${i}_dnssl${j}_lifetime
+	if [ -z "$ltime" -o "$ltime" = 0 ]; then
+		dnssl=
+	else
+		eval dnssl=\$nd${i}_dnssl${j}_search
+	fi
+
+	[ -z "$rdnss" -a -z "$dnssl" ] && return 1
+
+	new_rdnss="$new_rdnss${new_rdnss:+ }$rdnss"
+	new_dnssl="$new_dnssl${new_dnssl:+ }$dnssl"
+	j=$(($j + 1))
+	return 0
+}
+
 add_resolv_conf()
 {
 	local x= conf="$signature$NL" warn=true
-	local i j rdnss dnssl new_rdnss new_dnssl
+	local i j ltime rdnss dnssl new_rdnss new_dnssl
 
-	# Extract any ND DNS options from the RA
+	# Loop to extract the ND DNS options using our indexed shell values
 	i=1
 	j=1
 	while true; do
 		while true; do
-			eval rdnss=\$nd${i}_rdnss${j}_servers
-			eval dnssl=\$nd${i}_dnssl${j}_search
-			[ -z "$rdnss" -a -z "$dnssl" ] && break
-			new_rdnss="$new_rdnss${new_rdnss:+ }$rdnss"
-			new_dnssl="$new_dnssl${new_dnssl:+ }$dnssl"
-			j=$(($j + 1))
+			eval_nd_dns || break
 		done
 		i=$(($i + 1))
 		j=1
-		eval rdnss=\$nd${i}_rdnss${j}_servers
-		eval dnssl=\$nd${i}_dnssl${j}_search
-		[ -z "$rdnss" -a -z "$dnssl" ] && break
-		new_rdnss="$new_rdnss${new_rdnss:+ }$rdnss"
-		new_dnssl="$new_dnssl${new_dnssl:+ }$dnssl"
-		j=$(($j + 1))
+		eval_nd_dns || break
 	done
 	new_domain_name_servers="$new_domain_name_servers${new_domain_name_servers:+ }$new_rdnss"
 	new_domain_search="$new_domain_search${new_domain_search:+ }$new_dnssl"