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#ifndef UDP_SERVER_H
#define UDP_SERVER_H
#include "forward.h"
#include <boost/asio/ip/udp.hpp>
#include <boost/smart_ptr/enable_shared_from_this.hpp>
#include "common.h"
using lslboost::asio::ip::udp;
using lslboost::system::error_code;
namespace lsl {
/// shared pointer to a string
typedef lslboost::shared_ptr<std::string> string_p;
/// shared pointer to a socket
typedef lslboost::shared_ptr<udp::socket> udp_socket_p;
/*
* A lightweight UDP responder service.
* Understands the following messages:
* * LSL:shortinfo. This is a request for the stream_info that comes with a query string (and a return address). A packet is returned only if the query matches.
* * LSL:timedata. This is a request for time synchronization info that comes with a time stamp (t0). The t0 stamp and two more time stamps (t1 and t2) are returned (similar to the NTP packet exchange).
*/
class udp_server: public lslboost::enable_shared_from_this<udp_server> {
public:
/*
* Create a UDP responder that listens "side by side" with a TCP server.
* This server will listen on a free local port for timedata and shortinfo requests -- mainly for timing information (unless shortinfo is needed by clients).
* @param info The stream_info of the stream to serve (shared). After success, the appropriate service port will be assigned.
* @param protocol The protocol stack to use (tcp::v4() or tcp::v6()).
*/
udp_server(const stream_info_impl_p &info, lslboost::asio::io_context &io, udp protocol);
/**
* Create a new UDP server in multicast mode.
* This server will listen on a multicast address and responds only to LSL:shortinfo requests. This is for multicast/broadcast (and optionally unicast) local service discovery.
*/
udp_server(const stream_info_impl_p &info, lslboost::asio::io_context &io,
const std::string &address, uint16_t port, int ttl, const std::string &listen_address);
/// Start serving UDP traffic.
/// Call this only after the (shared) info object has been initialized by every involved party.
void begin_serving();
/// Initiate teardown of UDP traffic.
void end_serving();
private:
/// Initiate next packet request.
/// The result of the operation will eventually trigger the handle_receive_outcome() handler.
void request_next_packet();
/// Handler that gets called when a the next packet was received (or the op was cancelled).
void handle_receive_outcome(error_code err, std::size_t len);
/// Handler that gets called after a response packet has been sent off.
void handle_send_outcome(string_p replymsg, error_code err);
stream_info_impl_p info_; // stream_info reference
lslboost::asio::io_context &io_; // IO service reference
udp_socket_p socket_; // our socket
char buffer_[65536]; // a buffer of data (we're receiving on it)
bool time_services_enabled_; // whether the time services are enabled
udp::endpoint remote_endpoint_; // the endpoint that we're currently talking to
std::string shortinfo_msg_; // pre-computed server response
};
}
#endif