From 1022b72d08f8c62b8b75f7c06a23df999b53ff66 Mon Sep 17 00:00:00 2001
From: Jesse McDonald <nybble41@gmail.com>
Date: Sun, 3 May 2020 03:57:40 -0500
Subject: [PATCH] add option to get IF_NAME from default route

---
 src/tc-gen | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/src/tc-gen b/src/tc-gen
index 64cab92..ffa1ba7 100755
--- a/src/tc-gen
+++ b/src/tc-gen
@@ -508,6 +508,14 @@ while getopts ":i:u:d:b:f:q:c:C:p:xV" OPT; do
     esac
 done
 
+if [[ "${IF_NAME}" = "DEFAULT" ]]; then
+    IF_NAME="$(ip -j route | jq -r 'map(select(.dst=="default"))[0].dev' 2>&1)"
+    if [[ "$?" -ne 0 ]]; then
+	>&2 echo "ERROR: failed to determine the interface name for the default route"
+	exit 1
+    fi
+fi
+
 if [[ -z ${IF_NAME} ]]; then
     print_usage
     exit 1