-- Copyright (c) 2018-2021, OARC, Inc. -- 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 . -- dnsjit.output.dnscli -- DNS aware UDP/TCP/TLS client -- local dnscli = require("dnsjit.output.dnscli") -- .SS UDP Receiver Chain -- local output = dnscli.new(dnscli.UDP) -- output:connect("127.0.0.1", "53") -- input:receiver(output) -- .SS TCP Nonblocking -- local output = dnscli.new(dnscli.TCP + dnscli.NONBLOCKING) -- output:send(object) -- -- The DNS client can a -- .I core.object.dns -- or a -- .I core.object.payload -- object via the receiver interface or using -- .I send() -- and send it as DNS query after which it can receive the response by using -- the producer interface. -- If the object being sent is a -- .I core.object.dns -- then it will look at -- .I includes_dnslen -- attribute and depending on the protocol it will disregard, include or send -- the DNS length as an extra packet. -- If the object being sent is a -- .I core.object.payload -- then no special handling will be done and it will be sent as is. -- When receiving responses the producer interface will generate -- .I core.object.payload -- objects which may include the DNS length depending on the protocol used and -- must be handled by the caller. -- .SS MODES -- These transport modes and options are available when creating a new Dnscli -- output. -- .TP -- UDP -- Create an output using UDP. -- .TP -- TCP -- Create an output using TCP. -- .TP -- TLS -- Create an output using TCP and encrypt it with TLS. -- .TP -- NONBLOCKING -- Make the client nonblocking, see -- .I send() -- and -- .IR produce() . module(...,package.seeall) require("dnsjit.output.dnscli_h") local ffi = require("ffi") local C = ffi.C local t_name = "output_dnscli_t" local output_dnscli_t = ffi.typeof(t_name) local Dnscli = { NONBLOCKING = 0x1, UDP = 0x10, TCP = 0x20, TLS = 0x30, } -- Create a new Dnscli output. function Dnscli.new(mode) local self = { obj = output_dnscli_t(), } C.output_dnscli_init(self.obj, mode) ffi.gc(self.obj, C.output_dnscli_destroy) return setmetatable(self, { __index = Dnscli }) end -- Set or return the timeout used for sending and reciving, must be used before -- .IR connect() . function Dnscli:timeout(seconds, nanoseconds) if seconds == nil and nanoseconds == nil then return self.obj.timeout end if nanoseconds == nil then nanoseconds = 0 end self.obj.timeout.sec = seconds self.obj.timeout.nsec = nanoseconds end -- Connect to the -- .I host -- and -- .I port -- and return 0 if successful. function Dnscli:connect(host, port) return C.output_dnscli_connect(self.obj, host, port) end -- Return if nonblocking mode is on (true) or off (false). function Dnscli:nonblocking() if self.obj.nonblocking == 1 then return true end return false end -- Send an object and optionally continue sending after -- .I sent -- bytes. -- Unlike the receive interface this function lets you know if the sending was -- successful or not which might be needed on nonblocking connections. -- Returns -2 on error, -1 if interrupted, timed out or unable to send due to -- nonblocking, or the number of bytes sent. -- .B Note -- the counters for sent, received, errors and timeouts are not affected by -- this function. function Dnscli:send(object, sent) if sent == nil then sent = 0 end return C.output_dnscli_send(self.obj, object, sent) end -- Return the C functions and context for receiving objects, these objects -- will be sent. function Dnscli:receive() return C.output_dnscli_receiver(self.obj), self.obj end -- Return the C functions and context for producing objects, these objects -- are received. -- If nonblocking mode is enabled the producer will return a payload object -- with length zero if there was nothing to receive. -- If nonblocking mode is disabled the producer will wait for data and if -- timed out (see -- .IR timeout ) -- it will return a payload object with length zero. -- The producer returns nil on error. function Dnscli:produce() return C.output_dnscli_producer(self.obj), self.obj end -- Return the number of "packets" sent, actually the number of completely sent -- payloads. function Dnscli:packets() return tonumber(self.obj.pkts) end -- Return the number of "packets" received, actually the number of successful -- calls to -- .IR recvfrom (2) -- that returned data. function Dnscli:received() return tonumber(self.obj.pkts_recv) end -- Return the number of errors when sending or receiving. function Dnscli:errors() return tonumber(self.obj.errs) end -- Return the number of timeouts when sending or receiving. function Dnscli:timeouts() return tonumber(self.obj.timeouts) end -- core.object.dns (3), -- core.object.payload (3), -- core.timespec (3) return Dnscli