luci-base: luci.sys.iptparser: properly check for table support

Do not assume that the "raw" table is present on any system, instead check
/proc/net/ip{,6}_tables_names to determine which iptables tables are available.

Signed-off-by: Jo-Philipp Wich <jo@mein.io>

diff --git a/modules/luci-base/luasrc/sys/iptparser.lua b/modules/luci-base/luasrc/sys/iptparser.lua
index a9dbc308263143dfc16cf2b9bcc5288abc0e8df3..7ff665e7af427778a3fc8cb2c661c4b4bc928aeb 100644 (file)
--- a/modules/luci-base/luasrc/sys/iptparser.lua
+++ b/modules/luci-base/luasrc/sys/iptparser.lua
@@ -31,29 +31,43 @@ function IptParser.__init__( self, family )
        self._family = (tonumber(family) == 6) and 6 or 4
        self._rules  = { }
        self._chains = { }
+       self._tables = { }
+
+       local t = self._tables
+       local s = self:_supported_tables(self._family)
+
+       if s.filter then t[#t+1] = "filter" end
+       if s.nat    then t[#t+1] = "nat"    end
+       if s.mangle then t[#t+1] = "mangle" end
+       if s.raw    then t[#t+1] = "raw"    end
 
        if self._family == 4 then
                self._nulladdr = "0.0.0.0/0"
-               self._tables   = { "filter", "nat", "mangle", "raw" }
                self._command  = "iptables -t %s --line-numbers -nxvL"
        else
                self._nulladdr = "::/0"
-               self._tables   = { "filter", "mangle", "raw" }
-               local ok, lines = pcall(io.lines, "/proc/net/ip6_tables_names")
-               if ok and lines then
-                       local line
-                       for line in lines do
-                               if line == "nat" then
-                                       self._tables = { "filter", "nat", "mangle", "raw" }
-                               end
-                       end
-               end
                self._command  = "ip6tables -t %s --line-numbers -nxvL"
        end
 
        self:_parse_rules()
 end
 
+function IptParser._supported_tables( self, family )
+       local tables = { }
+       local ok, lines = pcall(io.lines,
+               (family == 6) and "/proc/net/ip6_tables_names"
+                              or "/proc/net/ip_tables_names")
+
+       if ok and lines then
+               local line
+               for line in lines do
+                       tables[line] = true
+               end
+       end
+
+       return tables
+end
+
 -- search criteria as only argument. If args is nil or an empty table then all
 -- rules will be returned.
 --