108 lines
3.7 KiB
C++
108 lines
3.7 KiB
C++
/*
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* Copyright (c) 2017, Matias Fontanini
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions are
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* met:
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*
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* * Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* * Redistributions in binary form must reproduce the above
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* copyright notice, this list of conditions and the following disclaimer
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* in the documentation and/or other materials provided with the
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* distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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* OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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* LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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* DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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* THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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* (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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* OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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*/
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#include <tins/tins.h>
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#include <iostream>
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using std::cout;
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using std::endl;
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using namespace Tins;
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PacketSender sender;
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bool callback(const PDU& pdu) {
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// The packet probably looks like this:
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//
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// EthernetII / IP / UDP / RawPDU
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//
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// So we retrieve each layer, and construct a
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// DNS PDU from the RawPDU layer contents.
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EthernetII eth = pdu.rfind_pdu<EthernetII>();
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IP ip = eth.rfind_pdu<IP>();
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UDP udp = ip.rfind_pdu<UDP>();
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DNS dns = udp.rfind_pdu<RawPDU>().to<DNS>();
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// Is it a DNS query?
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if (dns.type() == DNS::QUERY) {
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// Let's see if there's any query for an "A" record.
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for (const auto& query : dns.queries()) {
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if (query.query_type() == DNS::A) {
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// Here's one! Let's add an answer.
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dns.add_answer(
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DNS::resource(
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query.dname(),
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"127.0.0.1",
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DNS::A,
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query.query_class(),
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// 777 is just a random TTL
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777
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)
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);
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}
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}
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// Have we added some answers?
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if (dns.answers_count() > 0) {
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// It's a response now
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dns.type(DNS::RESPONSE);
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// Recursion is available(just in case)
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dns.recursion_available(1);
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// Build our packet
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auto pkt = EthernetII(eth.src_addr(), eth.dst_addr()) /
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IP(ip.src_addr(), ip.dst_addr()) /
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UDP(udp.sport(), udp.dport()) /
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dns;
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// Send it!
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sender.send(pkt);
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}
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}
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return true;
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}
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int main(int argc, char* argv[]) {
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if(argc != 2) {
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cout << "Usage: " <<* argv << " <interface>" << endl;
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return 1;
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}
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// Sniff on the provided interface in promiscuous mode
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SnifferConfiguration config;
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config.set_promisc_mode(true);
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// Use immediate mode so we get the packets as fast as we can
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config.set_immediate_mode(true);
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// Only capture udp packets sent to port 53
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config.set_filter("udp and dst port 53");
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Sniffer sniffer(argv[1], config);
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// All packets will be sent through the provided interface
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sender.default_interface(argv[1]);
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// Start the capture
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sniffer.sniff_loop(callback);
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}
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