getting VS C2664 on sniffer.h libtins - c++

Question

I'm working on a packet-capturing program.
I started from one of libtins examples on http http://libtins.github.io/examples/http-requests/.
but VS prompts a
C2664
Error C2664 'bool main::::operator ()(Tins::Packet &) const': cannot convert argument 1 from 'Tins::PDU' to 'Tins::Packet &' packetSniff path-to-tins\sniffer.h 681
on the following part of the sniffer.h
try {
// If the functor returns false, we're done
#if TINS_IS_CXX11 && !defined(_MSC_VER)
if (!Tins::Internals::invoke_loop_cb(function, *it)) {
return;
}
//here
#else
if (!function(*it->pdu())) {
return;
}
#endif
}
I have already build and run the example from the front page
http://libtins.github.io/
But the following code produces C2664
#define WIN32
#define TINS_STATIC
#define NOMINMAX
#pragma warning(disable : 4996)
#include <string>
#include <iostream>
#include <stdexcept>
#include <boost/regex.hpp>
#include <tins/tcp_ip/stream_follower.h>
#include <tins/sniffer.h>
#include <tins/tins.h>
#include "color.h"
#include <vector>
#include <sstream>
using std::string;
using std::cout;
using std::cerr;
using std::endl;
using std::exception;
using std::vector;
using std::wcout;
using std::stringstream;
using boost::regex;
using boost::match_results;
using Tins::Packet;
using Tins::Sniffer;
using Tins::SnifferConfiguration;
using Tins::TCPIP::Stream;
using Tins::TCPIP::StreamFollower;
using Tins::NetworkInterface;
using termcolor::on_red;
using termcolor::on_green;
using termcolor::reset;
// This example captures and follows TCP streams seen on port 80. It will
// wait until both the client and server send data and then apply a regex
// to both payloads, extrating some information and printing it.
// Don't buffer more than 3kb of data in either request/response
const size_t MAX_PAYLOAD = 3 * 1024;
// The regex to be applied on the request. This will extract the HTTP
// method being used, the request's path and the Host header value.
regex request_regex("([\\w]+) ([^ ]+).+\r\nHost: ([\\d\\w\\.-]+)\r\n");
// The regex to be applied on the response. This finds the response code.
regex response_regex("HTTP/[^ ]+ ([\\d]+)");
void on_server_data(Stream& stream) {
match_results<Stream::payload_type::const_iterator> client_match;
match_results<Stream::payload_type::const_iterator> server_match;
const Stream::payload_type& client_payload = stream.client_payload();
const Stream::payload_type& server_payload = stream.server_payload();
// Run the regexes on client/server payloads
bool valid = regex_search(server_payload.begin(), server_payload.end(),
server_match, response_regex) &&
regex_search(client_payload.begin(), client_payload.end(),
client_match, request_regex);
stringstream ss;
for (char c : server_payload) {
ss << c;
}
cout << on_green << "Server raw payload " <<
ss.str() << reset << endl;
// If we matched both the client and the server regexes
if (valid) {
// Extract all fields
string method = string(client_match[1].first, client_match[1].second);
string url = string(client_match[2].first, client_match[2].second);
string host = string(client_match[3].first, client_match[3].second);
string response_code = string(server_match[1].first, server_match[1].second);
// Now print them
cout << method << " http://" << host << url << " -> " << response_code << endl;
// Once we've seen the first request on this stream, ignore it
stream.ignore_client_data();
stream.ignore_server_data();
}
// Just in case the server returns invalid data, stop at 3kb
if (stream.server_payload().size() > MAX_PAYLOAD) {
stream.ignore_server_data();
}
}
void on_client_data(Stream& stream) {
// Don't hold more than 3kb of data from the client's flow
if (stream.client_payload().size() > MAX_PAYLOAD) {
stream.ignore_client_data();
}
}
void on_new_connection(Stream& stream) {
stream.client_data_callback(&on_client_data);
stream.server_data_callback(&on_server_data);
// Don't automatically cleanup the stream's data, as we'll manage
// the buffer ourselves and let it grow until we see a full request
// and response
stream.auto_cleanup_payloads(false);
}
int main(int argc, char* argv[]) {
// First fetch all network interfaces
vector<NetworkInterface> interfaces = NetworkInterface::all();
// Now iterate them
int i = 0;
for (const NetworkInterface& iface : interfaces) {
// First print the name (GUID)
cout << i++ << ' ' << "Interface name: " << termcolor::on_red << iface.name() <<
termcolor::on_cyan << ' ' << iface.addresses().ip_addr << termcolor::reset;
// Now print the friendly name, a wstring that will contain something like
// "Local Area Connection 2"
wcout << " (" << iface.friendly_name() << ")" << endl;
}
try {
// Construct the sniffer configuration object
SnifferConfiguration config;
// Only capture TCP traffic sent from/to port 80
config.set_filter("tcp port 5000");
// Construct the sniffer we'll use
Sniffer sniffer(interfaces[5].name(), config);
wcout << on_green <<"Starting capture on interface " <<
interfaces[5].friendly_name() << reset << endl;
// Now construct the stream follower
StreamFollower follower;
// We just need to specify the callback to be executed when a new
// stream is captured. In this stream, you should define which callbacks
// will be executed whenever new data is sent on that stream
// (see on_new_connection)
follower.new_stream_callback(&on_new_connection);
// Now start capturing. Every time there's a new packet, call
// follower.process_packet
sniffer.sniff_loop([&](Packet& packet) {
follower.process_packet(packet);
return true;
});
}
catch (exception& ex) {
cerr << "Error: " << ex.what() << endl;
return 1;
}
}

Answer 1

According to the code inside sniffer.h,
try {
// If the functor returns false, we're done
#if TINS_IS_CXX11 && !defined(_MSC_VER)
if (!Tins::Internals::invoke_loop_cb(function, *it)) {
return;
}
//here
#else
if (!function(*it->pdu())) {
return;
}
#endif
}
When you uses VS to compile, the macro _MSC_VER is defined by default, and your code will go to the #else branch, so it will call your callback with a PDU object. To avoid that I would suggest you to choose a different compiler or look for their instructions specifically for MSVC.

Answer 2

I finally came across a work around by casting it to Tins::Packet & in sniffer.h
if (!function((Tins::Packet &)*it->pdu())) {
return;
}