[nat] Add ip-tos option to the nat.

This is applied to all incoming BSC connections.
diff --git a/openbsc/src/nat/bsc_nat_vty.c b/openbsc/src/nat/bsc_nat_vty.c
index 56cd3c4..cef47d1 100644
--- a/openbsc/src/nat/bsc_nat_vty.c
+++ b/openbsc/src/nat/bsc_nat_vty.c
@@ -61,6 +61,7 @@
 	vty_out(vty, " timeout pong %d%s", _nat->pong_timeout, VTY_NEWLINE);
 	if (_nat->token)
 		vty_out(vty, " token %s%s", _nat->token, VTY_NEWLINE);
+	vty_out(vty, " ip-tos %d%s", _nat->bsc_ip_tos, VTY_NEWLINE);
 	return CMD_SUCCESS;
 }
 
@@ -297,6 +298,14 @@
 	return CMD_SUCCESS;
 }
 
+DEFUN(cfg_nat_bsc_ip_tos, cfg_nat_bsc_ip_tos_cmd,
+      "ip-tos <0-255>",
+      "Set the IP_TOS for the BSCs to use\n" "Set the IP_TOS attribute")
+{
+	_nat->bsc_ip_tos = atoi(argv[0]);
+	return CMD_SUCCESS;
+}
+
 /* per BSC configuration */
 DEFUN(cfg_bsc, cfg_bsc_cmd, "bsc BSC_NR", "Select a BSC to configure")
 {
@@ -458,6 +467,7 @@
 	install_element(NAT_NODE, &cfg_nat_ping_time_cmd);
 	install_element(NAT_NODE, &cfg_nat_pong_time_cmd);
 	install_element(NAT_NODE, &cfg_nat_token_cmd);
+	install_element(NAT_NODE, &cfg_nat_bsc_ip_tos_cmd);
 
 	/* BSC subgroups */
 	install_element(NAT_NODE, &cfg_bsc_cmd);