From: Roy Marples <roy@marples.name>
Date: Fri, 3 Jul 2009 23:32:30 +0000 (+0000)
Subject: Save the MTU when changing it.
X-Git-Tag: v5.0.6~9
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=62009c79586ff8465dfe6d91258aa0af527b0421;p=thirdparty%2Fdhcpcd.git

Save the MTU when changing it.
If we enter a state without a new MTU then restore the old one.
---

diff --git a/configure.c b/configure.c
index 11ea58a5..a74074c6 100644
--- a/configure.c
+++ b/configure.c
@@ -170,7 +170,7 @@ make_env(const struct interface *iface, char ***argv)
 	const struct interface *ifp;
 
 	/* Make our env */
-	elen = 7;
+	elen = 8;
 	env = xmalloc(sizeof(char *) * (elen + 1));
 	e = strlen("interface") + strlen(iface->name) + 2;
 	env[0] = xmalloc(e);
@@ -187,10 +187,12 @@ make_env(const struct interface *iface, char ***argv)
 	snprintf(env[4], e, "ifwireless=%d", iface->wireless);
 	env[5] = xmalloc(e);
 	snprintf(env[5], e, "ifflags=%u", iface->flags);
+	env[6] = xmalloc(e);
+	snprintf(env[6], e, "ifmtu=%d", get_mtu(iface->name));
 	l = e = strlen("interface_order=");
 	for (ifp = ifaces; ifp; ifp = ifp->next)
 		e += strlen(ifp->name) + 1;
-	p = env[6] = xmalloc(e);
+	p = env[7] = xmalloc(e);
 	strlcpy(p, "interface_order=", e);
 	e -= l;
 	p += l;
diff --git a/dhcpcd-hooks/10-mtu b/dhcpcd-hooks/10-mtu
index e4bb651c..a9f874d8 100644
--- a/dhcpcd-hooks/10-mtu
+++ b/dhcpcd-hooks/10-mtu
@@ -1,8 +1,22 @@
 # Configure the MTU for the interface
 
-if [ -n "$new_interface_mtu" ]; then
+mtu_dir="$state_dir/mtu"
+
+if [ "$reason" = PREINIT -a -e "$mtu_dir/$interface" ]; then
+	rm "$mtu_dir/$interface"
+elif [ -n "$new_interface_mtu" ]; then
 	# The smalled MTU dhcpcd can work with is 576
 	if [ "$new_interface_mtu" -ge 576 ]; then
-		ifconfig "$interface" mtu "$new_interface_mtu"
+		if ifconfig "$interface" mtu "$new_interface_mtu"; then
+			# Save the MTU so we can restore it later
+			if [ ! -e "$mtu_dir/$interface" ]; then
+				mkdir -p "$mtu_dir"
+				echo "$ifmtu" > "$mtu_dir/$interface"
+			fi
+		fi
 	fi
+elif [ -e "$mtu_dir/$interface" ]; then
+	# No MTU in this state, so restore the prior MTU
+	ifconfig "$interface" mtu $(cat "$mtu_dir/$interface")
+	rm "$mtu_dir/$interface"
 fi