spike(OPS50): probe gateway via /proc/net/route

.forgejo/workflows/spike-services.yml

@@ -25,7 +25,7 @@ jobs:
       - name: Probe gateway
         run: |
           set -uo pipefail
-          GW=$(ip route | awk '/default/ {print $3; exit}')
+          GW=$(awk '$2 == "00000000" {split($3, h, ""); ip=""; for (i=1; i<=8; i+=2) ip=ip strtonum("0x" h[i] h[i+1]) (i<8 ? "." : ""); print ip; exit}' /proc/net/route)
           echo "gateway=$GW"
           for i in $(seq 1 15); do
             if (echo > /dev/tcp/"$GW"/5433) 2>/dev/null; then