route-update.sh: derive table from rt_tables/IP, add options file with set-default

router/route-update.sh

@@ -70,10 +70,20 @@ MODES OF OPERATION:
 DIRECTORY STRUCTURE:
   routes.d/GROUP/gateway    Gateway IP(s), one per line. "default" = default gw.
                             Multiple lines = multipath (per-flow balancing).
-  routes.d/GROUP/table      Routing table number. ip rule pref = table × 10.
+  routes.d/GROUP/options    Optional flags, one per line:
+                              set-default  Also set system default route via gateway.
+  routes.d/GROUP/table      (legacy) Routing table number override.
   routes.d/GROUP/*.list     Symlinks to files with IPs, subnets, or domains.
   routes6.d/                Same structure for IPv6 groups.
 
+TABLE RESOLUTION:
+  Table number is determined by (in order):
+  1. routes.d/GROUP/table file (legacy, if present)
+  2. /etc/iproute2/rt_tables entry matching GROUP name
+  3. Last numeric component of gateway IP (e.g. 91.232.225.122 → 122),
+     auto-registered in rt_tables for future use.
+  ip rule pref = table_number × 10.
+
 EXAMPLES:
   ./route-update.sh                    # normal run
   ./route-update.sh --resolve -v       # re-resolve DNS, verbose
@@ -127,17 +137,55 @@ resolve_default_gw()
     $1 route show default | awk '/default/ {print $3; exit}'
 }
 
+# Look up table number: first from rt_tables by name, then from last IP octet
+# If derived from IP, auto-creates entry in rt_tables
+# Usage: lookup_table NAME GATEWAY
+lookup_table()
+{
+    local name="$1"
+    local gateway="$2"
+
+    # Try rt_tables first
+    local num=$(awk -v n="$name" '$2 == n { print $1; exit }' /etc/iproute2/rt_tables 2>/dev/null)
+    if [ -n "$num" ] ; then
+        echo "$num"
+        return
+    fi
+
+    # Fallback: last component of gateway IP
+    # IPv4: 91.232.225.122 → 122
+    # IPv6: 2a03:5a00:c:20::122 → 122
+    num=$(echo "$gateway" | sed -E 's/.*[.:]([0-9]+)$/\1/')
+
+    # Auto-register in rt_tables
+    if [ -n "$num" ] ; then
+        echo "$num	$name" >> /etc/iproute2/rt_tables
+        vlog "Added rt_tables entry: $num $name"
+    fi
+
+    echo "$num"
+}
+
+# Check if option is set in group's options file
+# Usage: has_option DIR OPTION
+has_option()
+{
+    [ -f "$1/options" ] && grep -q "^$2$" "$1/options" 2>/dev/null
+}
+
 # Read gateway and table from a group directory
-# Sets: gw, table, route_via
+# Sets: gw, table, route_via, opt_set_default
 #   gw        - first gateway (for display and IPv4/v6 detection)
-#   table     - routing table number
+#   table     - routing table number (from rt_tables or last IP octet)
 #   route_via - route suffix: "via GW table T" or "table T nexthop via GW1 ... nexthop via GW2 ..."
+#   opt_set_default - "1" if set-default option is enabled
 # $1 - directory, $2 - ip command ("ip" or "ip -6")
 read_group_config()
 {
     local dir="$1"
     local ipcmd="${2:-ip}"
-    gw="" ; table="" ; route_via=""
+    local name=$(basename "$dir")
+    gw="" ; table="" ; route_via="" ; opt_set_default=""
 
     if [ -f "$dir/gateway" ] ; then
         gw=$(grep -v '^#' "$dir/gateway" | grep -m1 .)
@@ -145,17 +193,25 @@ read_group_config()
             gw=$(resolve_default_gw "$ipcmd")
         fi
     else
-        echo "[$(basename "$dir")] No gateway file, skipping" >&2
+        echo "[$name] No gateway file, skipping" >&2
         return 1
     fi
 
+    # Table from file (legacy) or by name lookup
     if [ -f "$dir/table" ] ; then
         table=$(grep -v '^#' "$dir/table" | grep -m1 .)
     else
-        echo "[$(basename "$dir")] No table file, skipping" >&2
+        table=$(lookup_table "$name" "$gw")
+    fi
+
+    if [ -z "$table" ] ; then
+        echo "[$name] Cannot determine table number, skipping" >&2
         return 1
     fi
 
+    # Options
+    has_option "$dir" "set-default" && opt_set_default=1
+
     # Build route suffix: single vs multipath
     local gw_count=$(grep -v '^#' "$dir/gateway" | grep -c .)
     if [ "$gw_count" -le 1 ] ; then
@@ -267,8 +323,8 @@ process_routes()
             continue
         fi
 
-        # Compute hash of all list contents + gateway + table
-        local current_hash=$(md5_lists "$gwdir/gateway" "$gwdir/table" $lists)
+        # Compute hash of all list contents + gateway + options
+        local current_hash=$(md5_lists "$gwdir/gateway" "$gwdir/options" $lists)
 
         if [ -z "$FORCE" ] && [ -z "$RESOLVE" ] && [ -f "$STATE_DIR/$state/hash" ] ; then
             local saved_hash
@@ -363,6 +419,7 @@ process_routes()
             echo "  Would flush table $table and load $count routes"
             head -5 "$resolved_new" | sed 's/^/    /'
             [ "$count" -gt 5 ] && echo "    ... ($count total)"
+            [ -n "$opt_set_default" ] && echo "  Would set default route via $gw"
             rm -f "$resolved_new"
             continue
         fi
@@ -378,6 +435,17 @@ process_routes()
             $ipcmd rule add lookup "$table" pref "$pref" 2>/dev/null
         fi
 
+        # Set default route in main table if requested
+        if [ -n "$opt_set_default" ] ; then
+            local cur_default=$($ipcmd route show default | awk '/default/ {print $3; exit}')
+            if [ "$cur_default" != "$gw" ] ; then
+                log "[$name]$label Setting default route via $gw"
+                $ipcmd route replace default via "$gw"
+            else
+                vlog "[$name]$label default route already via $gw"
+            fi
+        fi
+
         # Save state
         echo "$current_hash" > "$STATE_DIR/$state/hash"
         echo "$table" > "$STATE_DIR/$state/table"
@@ -427,6 +495,13 @@ if [ -n "$SET_RULES" ] ; then
             if ! $ipcmd -N rule show | grep -q "lookup $table.*pref $pref" ; then
                 $ipcmd rule add lookup "$table" pref "$pref"
             fi
+            # Also restore default route if set-default
+            if [ -n "$opt_set_default" ] ; then
+                local cur_default=$($ipcmd route show default | awk '/default/ {print $3; exit}')
+                if [ "$cur_default" != "$gw" ] ; then
+                    $ipcmd route replace default via "$gw"
+                fi
+            fi
         done
     done
     exit