From f1c29980a836057ca20d838d3b96a03872dfbad8 Mon Sep 17 00:00:00 2001
From: Brian Candler <B.Candler@pobox.com>
Date: Tue, 3 May 2011 21:44:02 +0100
Subject: [PATCH] Non-functioning experiment at iptables netfilter support

---
 lib/netlink/c_struct.rb  |  2 ++
 lib/netlink/constants.rb | 53 ++++++++++++++++++++++++++++
 lib/netlink/iptables4.rb | 76 ++++++++++++++++++++++++++++++++++++++++
 3 files changed, 131 insertions(+)
 create mode 100644 lib/netlink/iptables4.rb

diff --git a/lib/netlink/c_struct.rb b/lib/netlink/c_struct.rb
index a7cb594..d1ba3cc 100644
--- a/lib/netlink/c_struct.rb
+++ b/lib/netlink/c_struct.rb
@@ -65,9 +65,11 @@ class CStruct
   define_type :uchar,   :pattern => "C"
   define_type :uint16,  :pattern => "S",  :align => true
   define_type :uint32,  :pattern => "L",  :align => true
+  define_type :uint64,  :pattern => "Q",  :align => true
   define_type :char,    :pattern => "c"
   define_type :int16,   :pattern => "s",  :align => true
   define_type :int32,   :pattern => "l",  :align => true
+  define_type :int64,   :pattern => "q",  :align => true
   define_type :ushort,  :pattern => "S_", :align => true
   define_type :uint,    :pattern => "I",  :align => true
   define_type :ulong,   :pattern => "L_", :align => true
diff --git a/lib/netlink/constants.rb b/lib/netlink/constants.rb
index 72c606c..10197c3 100644
--- a/lib/netlink/constants.rb
+++ b/lib/netlink/constants.rb
@@ -3,6 +3,8 @@ class Socket
   # From bits/socket.h
   PF_NETLINK		= 16		unless defined? Socket::PF_NETLINK
   AF_NETLINK		= PF_NETLINK	unless defined? Socket::AF_NETLINK
+  # From in.h
+  IPPROTO_IPV6		= 41		unless defined? Socket::IPPROTO_IPV6
 end
 
 module Netlink
@@ -327,6 +329,20 @@ module Netlink
   NF_REPEAT		= 4
   NF_STOP		= 5
 
+  NF_INET_PRE_ROUTING	= 0
+  NF_INET_LOCAL_IN	= 1
+  NF_INET_FORWARD	= 2
+  NF_INET_LOCAL_OUT	= 3
+  NF_INET_POST_ROUTING	= 4
+  NF_INET_NUMHOOKS	= 5
+    
+  NFPROTO_UNSPEC	= 0
+  NFPROTO_IPV4		= 2
+  NFPROTO_ARP		= 3
+  NFPROTO_BRIDGE	= 7
+  NFPROTO_IPV6		= 10
+  NFPROTO_DECNET	= 12
+
   # linux/netfilter_ipv4/ip_queue.h
   IPQ_COPY_NONE		= 0
   IPQ_COPY_META		= 1
@@ -340,4 +356,41 @@ module Netlink
   # linux/netfilter_ipv4/ipt_ULOG.h
   ULOG_MAC_LEN		= 80
   ULOG_PREFIX_LEN	= 32
+  
+  # linux/netfilter/x_tables.h
+  XT_TABLE_MAXNAMELEN	= 32
+  
+  XT_CONTINUE		= 0xffffffff
+  XT_RETURN		= (-NF_REPEAT - 1)
+
+  XT_INV_PROTO		= 0x40
+  
+  # linux/netfilter_ipv4/ip_tables.h
+  IPT_TABLE_MAXNAMELEN	= XT_TABLE_MAXNAMELEN
+  
+  IPT_F_FRAG		= 0x01
+  IPT_F_GOTO		= 0x02
+  IPT_F_MASK		= 0x03
+  
+  IPT_INV_VIA_IN	= 0x01
+  IPT_INV_VIA_OUT	= 0x02
+  IPT_INV_TOS		= 0x04
+  IPT_INV_SRCIP		= 0x08
+  IPT_INV_DSTIP		= 0x10
+  IPT_INV_FRAG		= 0x20
+  IPT_INV_PROTO		= XT_INV_PROTO
+  IPT_INV_MASK		= 0x7f
+  
+  IPT_BASE_CTL			= 64
+
+  IPT_SO_SET_REPLACE		= IPT_BASE_CTL
+  IPT_SO_SET_ADD_COUNTERS	= IPT_BASE_CTL + 1
+  
+  IPT_SO_GET_INFO		= IPT_BASE_CTL
+  IPT_SO_GET_ENTRIES		= IPT_BASE_CTL + 1
+  IPT_SO_GET_REVISION_MATCH	= IPT_BASE_CTL + 2
+  IPT_SO_GET_REVISION_TARGET	= IPT_BASE_CTL + 3
+  
+  IPT_CONTINUE			= XT_CONTINUE
+  IPT_RETURN			= XT_RETURN
 end
diff --git a/lib/netlink/iptables4.rb b/lib/netlink/iptables4.rb
new file mode 100644
index 0000000..475e2bc
--- /dev/null
+++ b/lib/netlink/iptables4.rb
@@ -0,0 +1,76 @@
+require 'socket'
+require 'netlink/c_struct'
+require 'netlink/message'  # just for :dev_name type
+require 'netlink/constants'
+
+module Netlink
+  #-
+  # Definitions mainly from linux/netfilter_ipv4/ip_tables.h
+  #+
+
+  # struct ipt_getinfo
+  class IPTGetInfo < CStruct
+    field :name, :pattern=>"Z#{IPT_TABLE_MAXNAMELEN}", :default=>EMPTY_STRING
+    field :valid_hooks, :int
+    #field :hook_entry, :pattern=>"I#{NF_INET_NUMHOOKS}", :default=>[0]*NF_INET_NUMHOOKS
+    #field :underflow, :pattern=>"I#{NF_INET_NUMHOOKS}", :default=>[0]*NF_INET_NUMHOOKS
+    field :hook_entry, :pattern=>"a#{NF_INET_NUMHOOKS*4}", :default=>EMPTY_STRING
+    field :underflow, :pattern=>"a#{NF_INET_NUMHOOKS*4}", :default=>EMPTY_STRING
+    field :num_entries, :int
+    field :size, :int
+  end
+
+  # struct ipt_get_entries
+  class IPTGetEntries < CStruct
+    field :name, :pattern=>"Z#{IPT_TABLE_MAXNAMELEN}", :default=>EMPTY_STRING
+    field :size, :uint
+    #field :entrytable, :pattern=>
+    field :entrytable, :binary   # struct ipt_entry entrytable[]
+  end
+  
+  # struct ipt_entry
+  class IPTEntry < CStruct
+    #### struct ipt_ip
+    field :src, :nl   # struct in_addr
+    field :dst, :nl
+    field :smsk, :nl
+    field :dmsk, :nl
+    field :iniface, :dev_name
+    field :outiface, :dev_name
+    field :iniface_mask, :dev_name
+    field :outiface_mask, :dev_name
+    field :proto, :uint16
+    field :flags, :uchar
+    field :invflags, :uchar
+    ####
+    field :nfcache, :int
+    field :target_offset, :uint16
+    field :next_offset, :uint16
+    field :comefrom, :uint
+    field :packet_count, :uint64
+    field :byte_count, :uint64
+    field :elems, :binary
+  end
+
+  # Class for handling iptables. Note that this doesn't actually use
+  # Netlink at all :-(
+  class Iptables4
+    TC_AF = Socket::AF_INET
+    TC_IPPROTO = Socket::IPPROTO_IP
+    SO_GET_INFO = IPT_SO_GET_INFO
+    STRUCT_GETINFO = IPTGetInfo
+    STRUCT_GET_ENTRIES = IPTGetEntries
+
+    def initialize(tablename = "filter")
+      @socket = Socket.new(TC_AF, Socket::SOCK_RAW, Socket::IPPROTO_RAW)
+      info = STRUCT_GETINFO.new(:name => tablename)
+      # FIXME: ruby won't let us pass structure to getsockopt!!
+      @socket.getsockopt(TC_IPPROTO, SO_GET_INFO, info)
+      warn "valid_hooks=0x%08x, num_entries=%d, size=%d" % [info.valid_hooks, info.size, info.num_entries]
+    end
+  end
+end
+
+if __FILE__ == $0
+  iptables = Netlink::Iptables4.new
+end