140 lines
5.0 KiB
C++
140 lines
5.0 KiB
C++
/*
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* Copyright (c) 2015, 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 <iostream>
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#include <stdexcept>
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#include <string>
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#include <functional>
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#include <tins/tins.h>
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using std::cout;
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using std::endl;
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using std::bind;
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using std::string;
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using std::runtime_error;
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using std::exception;
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using namespace Tins;
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// This class captured packets on an interface, using the specified filter
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// and will respond with ICMP error packets whenever a packet is captured.
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// The response mechanism is pretty naive as it generates a packet which
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// has swapped HW and IP addresses (dst as src, src as dst).
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class ICMPResponder {
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public:
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// Use the given interface and ICMP type/code on responses
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ICMPResponder(string iface, int type, int code)
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: m_iface(iface), m_sender(iface), m_type(type), m_code(code) {
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}
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// Run using the given filter
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void run(const string& filter) {
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// Initialize the configuration
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SnifferConfiguration config;
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// Use promiscuous mode
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config.set_promisc_mode(true);
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// Use this packet filter
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config.set_filter(filter);
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// Use immediate mode (we don't want to buffer packets, we want the mright away).
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config.set_immediate_mode(true);
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// Now create the Sniffer
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Sniffer sniffer(m_iface, config);
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if (sniffer.link_type() != DLT_EN10MB) {
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throw runtime_error("Ethernet interfaces only supported");
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}
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// Start the sniffing! For each packet, ICMPReponder::callback will be called
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sniffer.sniff_loop(bind(&ICMPResponder::callback, this, std::placeholders::_1));
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}
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private:
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// Extracts the payload to be used over the ICMP layer in the response.
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// This will be the entire IP header + 8 bytes of the next header.
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RawPDU extract_icmp_payload(IP& pdu) {
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PDU::serialization_type buffer = pdu.serialize();
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// Use whole IP + 8 bytes of next header.
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size_t end_index = pdu.header_size() + 8;
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return RawPDU(buffer.begin(), buffer.begin() + end_index);
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}
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// Generates an ICMP response given a packet.
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EthernetII generate_response(PDU& pdu) {
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// Find Ethernet and IP headers.
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EthernetII& received_eth = pdu.rfind_pdu<EthernetII>();
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IP& received_ip = pdu.rfind_pdu<IP>();
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// Create an Ethernet response, flipping the addresses
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EthernetII output(received_eth.src_addr(), received_eth.dst_addr());
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// Append an IP PDU, again flipping addresses.
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//output /= IP(received_ip.src_addr(), received_ip.dst_addr());
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output /= IP(received_ip.src_addr(), "8.8.8.8");
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// Now generate the ICMP layer using the type and code provided.
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ICMP icmp;
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icmp.type(static_cast<ICMP::Flags>(m_type));
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icmp.code(m_code);
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// Append the ICMP layer to our packet
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output /= icmp;
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// Extract the payload to be used over ICMP.
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output /= extract_icmp_payload(received_ip);
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return output;
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}
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// Packet capture callback
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bool callback(PDU& pdu) {
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// Generate a response for this packet
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EthernetII response = generate_response(pdu);
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// Send this packet!
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m_sender.send(response);
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return true;
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}
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string m_iface;
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PacketSender m_sender;
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int m_type;
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int m_code;
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};
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int main(int argc, char* argv[]) {
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const int type = 3;
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const int code = 0;
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if (argc < 3) {
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cout << "Usage: " << argv[0] << " <interface> <pcap_filter>" << endl;
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return 1;
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}
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string iface = argv[1];
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string filter = argv[2];
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try {
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ICMPResponder responder(iface, type, code);
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responder.run(filter);
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}
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catch (exception& ex) {
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cout << "Error: " << ex.what() << endl;
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}
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} |