functions: check extra DNS availability before resolving

router/functions

@@ -43,18 +43,31 @@ resolve_gw()
 
 # --- DNS resolution ---
 
+# Check if external DNS is reachable. Sets EXTRA_DNS=IP or EXTRA_DNS=
+# Include $EXTRA_DNS in hash so re-resolve triggers when availability changes
+EXTRA_DNS_SERVER=8.8.8.8
+
+check_extra_dns()
+{
+    if dig @$EXTRA_DNS_SERVER +short +time=1 +tries=1 google.com A >/dev/null 2>&1 ; then
+        EXTRA_DNS=$EXTRA_DNS_SERVER
+    else
+        EXTRA_DNS=
+    fi
+}
+
 get_ipv4_list()
 {
     echo "$1" | grep -q "[a-z]" || return 0
     dig "$1" A | grep -v "^;" | grep "IN[[:space:]]*A[[:space:]]" | sed -e "s|.*[[:space:]]||" | sort
-    dig @8.8.8.8 "$1" A | grep -v "^;" | grep "IN[[:space:]]*A[[:space:]]" | sed -e "s|.*[[:space:]]||" | sort
+    [ -n "$EXTRA_DNS" ] && dig @$EXTRA_DNS "$1" A | grep -v "^;" | grep "IN[[:space:]]*A[[:space:]]" | sed -e "s|.*[[:space:]]||" | sort
 }
 
 get_ipv6_list()
 {
     echo "$1" | grep -q "[a-z]" || return 0
     dig "$1" AAAA | grep -v "^;" | grep "IN[[:space:]]*AAAA[[:space:]]" | sed -e "s|.*[[:space:]]||" | sort
-    dig @8.8.8.8 "$1" AAAA | grep -v "^;" | grep "IN[[:space:]]*AAAA[[:space:]]" | sed -e "s|.*[[:space:]]||" | sort
+    [ -n "$EXTRA_DNS" ] && dig @$EXTRA_DNS "$1" AAAA | grep -v "^;" | grep "IN[[:space:]]*AAAA[[:space:]]" | sed -e "s|.*[[:space:]]||" | sort
 }
 
 is_ipv4()
@@ -122,11 +135,10 @@ get_ipv4_list_bulk()
 
     [ -s "$domains" ] || return 0
 
-    # Bulk async resolve: local resolver + Google DNS
-    # -a: async, -Fi: inline parseable (answers+errors to stdout), -f: read from stdin
+    # Bulk async resolve: local resolver + Google DNS (if reachable)
     {
         adnshost -a -t a -Fi -f < "$domains"
-        adnshost -a -t a -Fi -f --config "nameserver 8.8.8.8" < "$domains"
+        [ -n "$EXTRA_DNS" ] && adnshost -a -t a -Fi -f --config "nameserver $EXTRA_DNS" < "$domains"
     } > "$adns_out" 2>/dev/null
 
     # Output resolved IPs grouped by domain
@@ -166,10 +178,10 @@ get_ipv6_list_bulk()
 
     [ -s "$domains" ] || return 0
 
-    # Bulk async resolve: local resolver + Google DNS
+    # Bulk async resolve: local resolver + Google DNS (if reachable)
     {
         adnshost -a -t aaaa -Fi -f < "$domains"
-        adnshost -a -t aaaa -Fi -f --config "nameserver 8.8.8.8" < "$domains"
+        [ -n "$EXTRA_DNS" ] && adnshost -a -t aaaa -Fi -f --config "nameserver $EXTRA_DNS" < "$domains"
     } > "$adns_out" 2>/dev/null
 
     # Output resolved IPs grouped by domain

router/route-update.sh

@@ -285,7 +285,7 @@ process_routes()
 
         # Compute hashes: lists only (for resolve skip) and full (for change detect)
         local lists_hash=$(md5_lists $lists)
-        local current_hash=$(md5_lists "$gwdir/gateway" "$gwdir/options" $lists)
+        local current_hash=$( { echo "dns=$EXTRA_DNS"; cat "$gwdir/gateway" "$gwdir/options" $lists; } 2>/dev/null | md5sum | awk '{print $1}')
         local need_reload= need_resolve=1
 
         if [ -z "$FORCE" ] && [ -z "$RESOLVE" ] && [ -f "$STATE_DIR/$state/hash" ] ; then
@@ -465,6 +465,9 @@ cleanup_state()
 [ -n "$SHOW" ] && log "Dry-run mode (no changes will be made)"
 [ -n "$VERBOSE" ] && log "Verbose mode, state_dir=$STATE_DIR"
 
+check_extra_dns
+[ -n "$EXTRA_DNS" ] && vlog "Extra DNS: $EXTRA_DNS" || log "Extra DNS ($EXTRA_DNS_SERVER) unreachable, local resolver only"
+
 process_routes "$ROUTES_DIR" get_ipv4_list_bulk "ip" ""
 process_routes "$ROUTES6_DIR" get_ipv6_list_bulk "ip -6" " (v6)"
 cleanup_state