From 9b59388a58bd79db6d43e169c0fb7903f6bff0d1 Mon Sep 17 00:00:00 2001
From: Harald Ringvold <harald.ringvold@gmail.com>
Date: Sat, 20 Mar 2021 21:09:58 +0100
Subject: [PATCH] Adding check for valid ip address

In some cases the return body from ifconfig.co is an HTML error page.
This change makes sure the response is a valid IP address.
---
 dyndns.sh | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/dyndns.sh b/dyndns.sh
index 724c71d..f17a281 100755
--- a/dyndns.sh
+++ b/dyndns.sh
@@ -30,7 +30,8 @@ while ( true ); do
         echo "Trying with $service..."
 
         ip="$(curl -s $service)"
-        test -n "$ip" && break
+        valid_ip=$(echo $ip | grep '[0-9]\{1,3\}\(\.[0-9]\{1,3\}\)\{3\}')
+        test -n "$valid_ip" && break
     done
     
     echo "Found IP address $ip"