1 files changed, 122 insertions, 0 deletions
diff --git a/include/dnsjit/filter/ipsplit.lua b/include/dnsjit/filter/ipsplit.lua
new file mode 100644
index 0000000..cca0249
--- /dev/null
+++ b/include/dnsjit/filter/ipsplit.lua
@@ -0,0 +1,122 @@
+-- Copyright (c) 2019-2020 CZ.NIC, z.s.p.o.
+-- All rights reserved.
+--
+-- This file is part of dnsjit.
+--
+-- dnsjit is free software: you can redistribute it and/or modify
+-- it under the terms of the GNU General Public License as published by
+-- the Free Software Foundation, either version 3 of the License, or
+-- (at your option) any later version.
+--
+-- dnsjit is distributed in the hope that it will be useful,
+-- but WITHOUT ANY WARRANTY; without even the implied warranty of
+-- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+-- GNU General Public License for more details.
+--
+-- You should have received a copy of the GNU General Public License
+-- along with dnsjit.  If not, see <http://www.gnu.org/licenses/>.
+
+-- dnsjit.filter.ipsplit
+-- Pass objects to receivers based on the source IP address
+--   local ipsplit = require("dnsjit.filter.ipsplit").new()
+--   ipsplit.receiver(...)
+--   ipsplit.receiver(...)
+--   ipsplit.receiver(...)
+--   input.receiver(ipsplit)
+--
+-- The filter passes objects to other receivers.
+-- Object chains without IPv4/IPv6 packet are discarded.
+-- Packets which have the same source IP address are considered to be sent
+-- from the same "client".
+-- When the first packet from a client is processed, the client is assigned
+-- to a receiver.
+-- All objects from this client will be passed to the assigned receiver.
+-- The filter can also write a receiver-specific client ID (starting from 1)
+-- to the source or destination IP in the packet.
+module(...,package.seeall)
+
+require("dnsjit.filter.ipsplit_h")
+local bit = require("bit")
+local object = require("dnsjit.core.objects")
+local ffi = require("ffi")
+local C = ffi.C
+
+local IpSplit = {}
+
+-- Create a new IpSplit filter.
+function IpSplit.new()
+    local self = {
+        obj = C.filter_ipsplit_new(),
+    }
+    ffi.gc(self.obj, C.filter_ipsplit_free)
+    return setmetatable(self, { __index = IpSplit })
+end
+
+-- Return the Log object to control logging of this instance or module.
+function IpSplit:log()
+    if self == nil then
+        return C.filter_ipsplit_log()
+    end
+    return self.obj._log
+end
+
+-- Return the C functions and context for receiving objects.
+function IpSplit:receive()
+    local recv = C.filter_ipsplit_receiver(self.obj)
+    return recv, self.obj
+end
+
+-- Set the receiver to pass objects to, this can be called multiple times to
+-- set additional receivers.
+-- The weight parameter can be used to adjust distribution of clients among
+-- receivers.
+-- Weight must be a positive integer (default is 1).
+function IpSplit:receiver(o, weight)
+    local recv, ctx = o:receive()
+    if weight == nil then
+        weight = 1
+    end
+    C.filter_ipsplit_add(self.obj, recv, ctx, weight)
+end
+
+-- Number of input packets discarded due to various reasons.
+-- To investigate causes, run with increased logging level.
+function IpSplit:discarded()
+    return tonumber(self.obj.discarded)
+end
+
+-- Set the client assignment mode to sequential.
+-- Assigns `weight` clients to a receiver before continuing with the next
+-- receiver (default mode).
+function IpSplit:sequential()
+    self.obj.mode = "IPSPLIT_MODE_SEQUENTIAL"
+end
+
+-- Set the client assignment mode to random.
+-- Each client is randomly assigned to a receiver (weight affects the
+-- probability).
+-- The client assignment is stable (and portable) for given seed.
+function IpSplit:random(seed)
+    self.obj.mode = "IPSPLIT_MODE_RANDOM"
+    if seed then
+        C.filter_ipsplit_srand(seed)
+    end
+end
+
+-- Don't overwrite source or destination IP (default).
+function IpSplit:overwrite_none()
+    self.obj.overwrite = "IPSPLIT_OVERWRITE_NONE"
+end
+
+-- Write receiver-specific client ID to bytes 0-3 of source IP (host byte order).
+function IpSplit:overwrite_src()
+    self.obj.overwrite = "IPSPLIT_OVERWRITE_SRC"
+end
+
+-- Write receiver-specific client ID to bytes 0-3 of destination IP (host byte
+-- order).
+function IpSplit:overwrite_dst()
+    self.obj.overwrite = "IPSPLIT_OVERWRITE_DST"
+end
+
+return IpSplit