[openwrt/openwrt] umbim: respect 'Enable IPv6 negotiation' option

[LEDE Commits]

hauke pushed a commit to openwrt/openwrt.git, branch master:
https://git.openwrt.org/e2655e0a6beacc45ae763b509cb447d4777aecf6

commit e2655e0a6beacc45ae763b509cb447d4777aecf6
Author: Lech Perczak <lech.perczak at gmail.com>
AuthorDate: Tue Jul 20 22:57:10 2021 +0200

    umbim: respect 'Enable IPv6 negotiation' option
    
    Don't bring IPv6 part of interface up if it's disabled,
    or system does not support it.
    
    Signed-off-by: Lech Perczak <lech.perczak at gmail.com>
---
 package/network/utils/umbim/files/lib/netifd/proto/mbim.sh | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/package/network/utils/umbim/files/lib/netifd/proto/mbim.sh b/package/network/utils/umbim/files/lib/netifd/proto/mbim.sh
index 294dc64400..aee0feb4ba 100755
--- a/package/network/utils/umbim/files/lib/netifd/proto/mbim.sh
+++ b/package/network/utils/umbim/files/lib/netifd/proto/mbim.sh
@@ -19,6 +19,7 @@ proto_mbim_init_config() {
 	proto_config_add_string auth
 	proto_config_add_string username
 	proto_config_add_string password
+	[ -e /proc/sys/net/ipv6 ] && proto_config_add_string ipv6
 	proto_config_add_boolean dhcp
 	proto_config_add_boolean dhcpv6
 	proto_config_add_string pdptype
@@ -33,6 +34,8 @@ _proto_mbim_setup() {
 	local device apn pincode delay allow_roaming allow_partner dhcp dhcpv6 pdptype $PROTO_DEFAULT_OPTIONS
 	json_get_vars device apn pincode delay auth username password allow_roaming allow_partner dhcp dhcpv6 pdptype $PROTO_DEFAULT_OPTIONS
 
+	[ ! -e /proc/sys/net/ipv6 ] && ipv6=0 || json_get_var ipv6 ipv6
+
 	[ -n "$ctl_device" ] && device=$ctl_device
 
 	[ -n "$device" ] || {
@@ -150,6 +153,7 @@ _proto_mbim_setup() {
 	tid=$((tid + 1))
 
 	pdptype=$(echo "$pdptype" | awk '{print tolower($0)}')
+	[ "$ipv6" = 0 ] && pdptype="ipv4"
 
 	local req_pdptype="" # Pass "default" PDP type to umbim if unconfigured
 	[ "$pdptype" = "ipv4" -o "$pdptype" = "ipv6" -o "$pdptype" = "ipv4v6" ] && req_pdptype="$pdptype:"