[openwrt/openwrt] odhcp6c: add mtu_dslite option for dhcpv6 proto

[LEDE Commits]

robimarko pushed a commit to openwrt/openwrt.git, branch main:
https://git.openwrt.org/38a0d6b1fd4e34a4b89b88a0986ef1263139cf2c

commit 38a0d6b1fd4e34a4b89b88a0986ef1263139cf2c
Author: Mateusz Poliwczak <mpoliwczak34 at gmail.com>
AuthorDate: Fri Oct 31 11:57:14 2025 +0100

    odhcp6c: add mtu_dslite option for dhcpv6 proto
    
    This allow configuring the MTU of the ds-lite tunnel.
    
    Updates #8190
    
    Signed-off-by: Mateusz Poliwczak <mpoliwczak34 at gmail.com>
    Link: https://github.com/openwrt/openwrt/pull/20606
    Signed-off-by: Robert Marko <robimarko at gmail.com>
---
 package/network/ipv6/odhcp6c/files/dhcpv6.script | 1 +
 package/network/ipv6/odhcp6c/files/dhcpv6.sh     | 6 ++++--
 2 files changed, 5 insertions(+), 2 deletions(-)

diff --git a/package/network/ipv6/odhcp6c/files/dhcpv6.script b/package/network/ipv6/odhcp6c/files/dhcpv6.script
index b1a99ed986..bbdd80c904 100755
--- a/package/network/ipv6/odhcp6c/files/dhcpv6.script
+++ b/package/network/ipv6/odhcp6c/files/dhcpv6.script
@@ -192,6 +192,7 @@ setup_interface () {
 		json_add_string tunlink "$INTERFACE"
 		[ -n "$ZONE_DSLITE" ] || ZONE_DSLITE=$ZONE
 		[ -n "$ZONE_DSLITE" ] && json_add_string zone "$ZONE_DSLITE"
+		[ -n "$MTU_DSLITE" ] && json_add_string mtu "$MTU_DSLITE"
 		[ -n "$ENCAPLIMIT_DSLITE" ] && json_add_string encaplimit "$ENCAPLIMIT_DSLITE"
 		[ -n "$IFACE_DSLITE_DELEGATE" ] && json_add_boolean delegate "$IFACE_DSLITE_DELEGATE"
 		json_close_object
diff --git a/package/network/ipv6/odhcp6c/files/dhcpv6.sh b/package/network/ipv6/odhcp6c/files/dhcpv6.sh
index ce530f0ef0..2006ceb567 100755
--- a/package/network/ipv6/odhcp6c/files/dhcpv6.sh
+++ b/package/network/ipv6/odhcp6c/files/dhcpv6.sh
@@ -24,6 +24,7 @@ proto_dhcpv6_init_config() {
 	proto_config_add_string iface_dslite
 	proto_config_add_string zone_dslite
 	proto_config_add_string encaplimit_dslite
+	proto_config_add_int mtu_dslite
 	proto_config_add_string iface_map
 	proto_config_add_string zone_map
 	proto_config_add_string encaplimit_map
@@ -56,8 +57,8 @@ proto_dhcpv6_setup() {
 	local config="$1"
 	local iface="$2"
 
-	local reqaddress reqprefix clientid reqopts defaultreqopts noslaaconly forceprefix extendprefix norelease noserverunicast noclientfqdn noacceptreconfig ip6prefix ip6prefixes iface_dslite iface_map iface_464xlat ip6ifaceid userclass vendorclass sendopts delegate zone_dslite zone_map zone_464xlat zone encaplimit_dslite encaplimit_map skpriority soltimeout fakeroutes sourcefilter keep_ra_dnslifetime ra_holdoff verbose
-	json_get_vars reqaddress reqprefix clientid reqopts defaultreqopts noslaaconly forceprefix extendprefix norelease noserverunicast noclientfqdn noacceptreconfig iface_dslite iface_map iface_464xlat ip6ifaceid userclass vendorclass delegate zone_dslite zone_map zone_464xlat zone encaplimit_dslite encaplimit_map skpriority soltimeout fakeroutes sourcefilter keep_ra_dnslifetime ra_holdoff verbose
+	local reqaddress reqprefix clientid reqopts defaultreqopts noslaaconly forceprefix extendprefix norelease noserverunicast noclientfqdn noacceptreconfig ip6prefix ip6prefixes iface_dslite iface_map iface_464xlat ip6ifaceid userclass vendorclass sendopts delegate zone_dslite zone_map zone_464xlat zone encaplimit_dslite encaplimit_map skpriority soltimeout fakeroutes sourcefilter keep_ra_dnslifetime ra_holdoff verbose mtu_dslite
+	json_get_vars reqaddress reqprefix clientid reqopts defaultreqopts noslaaconly forceprefix extendprefix norelease noserverunicast noclientfqdn noacceptreconfig iface_dslite iface_map iface_464xlat ip6ifaceid userclass vendorclass delegate zone_dslite zone_map zone_464xlat zone encaplimit_dslite encaplimit_map skpriority soltimeout fakeroutes sourcefilter keep_ra_dnslifetime ra_holdoff verbose mtu_dslite
 	json_for_each_item proto_dhcpv6_add_prefix ip6prefix ip6prefixes
 
 	# Configure
@@ -120,6 +121,7 @@ proto_dhcpv6_setup() {
 
 	[ -n "$ip6prefixes" ] && proto_export "USERPREFIX=$ip6prefixes"
 	[ -n "$iface_dslite" ] && proto_export "IFACE_DSLITE=$iface_dslite"
+	[ -n "$mtu_dslite" ] && proto_export "MTU_DSLITE=$mtu_dslite"
 	[ -n "$iface_map" ] && proto_export "IFACE_MAP=$iface_map"
 	[ -n "$iface_464xlat" ] && proto_export "IFACE_464XLAT=$iface_464xlat"
 	[ "$delegate" = "0" ] && proto_export "IFACE_DSLITE_DELEGATE=0"