piholeDebug - Get default route robustly

    Determine address and interface of default route by preceeding
    'via' and 'dev' fields in json output instead of plain text
    field position.

    Log if unable to determine default gateway

Signed-off-by: Rob Gill <rrobgill@protonmail.com>

diff --git a/advanced/Scripts/piholeDebug.sh b/advanced/Scripts/piholeDebug.sh
index 741ff2f48e313f4bda03762276c7ad055b1fc783..e4bd11913bfb2573f2a3416c5be2b23f526e1bd4 100755 (executable)
--- a/advanced/Scripts/piholeDebug.sh
+++ b/advanced/Scripts/piholeDebug.sh
@@ -497,16 +497,25 @@ ping_gateway() {
     ping_ipv4_or_ipv6 "${protocol}"
     # Check if we are using IPv4 or IPv6
     # Find the default gateways using IPv4 or IPv6
-    local gateway gateway_addr gateway_iface
+    local gateway gateway_addr gateway_iface default_route
 
     log_write "${INFO} Default IPv${protocol} gateway(s):"
 
-    while IFS= read -r gateway; do
-        log_write "     $(cut -d ' ' -f 3 <<< "${gateway}")%$(cut -d ' ' -f 5 <<< "${gateway}")"
-    done < <(ip -"${protocol}" route | grep default)
+    while IFS= read -r default_route; do
+        gateway_addr=$(jq -r '.gateway' <<< "${default_route}")
+        gateway_iface=$(jq -r '.dev' <<< "${default_route}")
+        log_write "     ${gateway_addr}%${gateway_iface}"
+    done < <(ip -j -"${protocol}" route | jq -c '.[] | select(.dst == "default")')
+
+    # Find the first default route
+    default_route=$(ip -j -"${protocol}" route show default)
+    if echo "$default_route" | grep 'gateway' | grep -q 'dev'; then
+        gateway_addr=$(echo "$default_route" | jq -r -c '.[0].gateway')
+        gateway_iface=$(echo "$default_route" | jq -r -c '.[0].dev')
+    else
+        log_write "     Unable to determine gateway address for IPv${protocol}"
+    fi
 
-    gateway_addr=$(ip -"${protocol}" route | grep default | cut -d ' ' -f 3 | head -n 1)
-    gateway_iface=$(ip -"${protocol}" route | grep default | cut -d ' ' -f 5 | head -n 1)
     # If there was at least one gateway
     if [ -n "${gateway_addr}" ]; then
         # Append the interface to the gateway address if it is a link-local address