//====== Copyright Valve Corporation, All rights reserved. ====================
//
// Networking API similar to Berkeley sockets, but for games.
// - connection-oriented API (like TCP, not UDP)
// - but unlike TCP, it's message-oriented, not stream-oriented
// - mix of reliable and unreliable messages
// - fragmentation and reassembly
// - Supports connectivity over plain UDPv4
// - Also supports SDR ("Steam Datagram Relay") connections, which are
//   addressed by SteamID.  There is a "P2P" use case and also a "hosted
//   dedicated server" use case.
//
//=============================================================================

#ifndef ISTEAMNETWORKINGSOCKETS
#define ISTEAMNETWORKINGSOCKETS
#ifdef _WIN32
#pragma once
#endif

#include "steamnetworkingtypes.h"

class ISteamNetworkingSocketsCallbacks;
struct SteamNetAuthenticationStatus_t;
class ISteamNetworkingConnectionCustomSignaling;
class ISteamNetworkingCustomSignalingRecvContext;

//-----------------------------------------------------------------------------
/// Lower level networking interface that more closely mirrors the standard
/// Berkeley sockets model.  Sockets are hard!  You should probably only use
/// this interface under the existing circumstances:
///
/// - You have an existing socket-based codebase you want to port, or coexist with.
/// - You want to be able to connect based on IP address, rather than (just) Steam ID.
/// - You need low-level control of bandwidth utilization, when to drop packets, etc.
///
/// Note that neither of the terms "connection" and "socket" will correspond
/// one-to-one with an underlying UDP socket.  An attempt has been made to
/// keep the semantics as similar to the standard socket model when appropriate,
/// but some deviations do exist.
class ISteamNetworkingSockets
{
public:

	/// Creates a "server" socket that listens for clients to connect to by 
	/// calling ConnectByIPAddress, over ordinary UDP (IPv4 or IPv6)
	///
	/// You must select a specific local port to listen on and set it
	/// the port field of the local address.
	///
	/// Usually you will set the IP portion of the address to zero (SteamNetworkingIPAddr::Clear()).
	/// This means that you will not bind to any particular local interface (i.e. the same
	/// as INADDR_ANY in plain socket code).  Furthermore, if possible the socket will be bound
	/// in "dual stack" mode, which means that it can accept both IPv4 and IPv6 client connections.
	/// If you really do wish to bind a particular interface, then set the local address to the
	/// appropriate IPv4 or IPv6 IP.
	///
	/// If you need to set any initial config options, pass them here.  See
	/// SteamNetworkingConfigValue_t for more about why this is preferable to
	/// setting the options "immediately" after creation.
	///
	/// When a client attempts to connect, a SteamNetConnectionStatusChangedCallback_t
	/// will be posted.  The connection will be in the connecting state.
	virtual HSteamListenSocket CreateListenSocketIP( const SteamNetworkingIPAddr *localAddress, int nOptions, const SteamNetworkingConfigValue_t *pOptions ) = 0;

	/// Creates a connection and begins talking to a "server" over UDP at the
	/// given IPv4 or IPv6 address.  The remote host must be listening with a
	/// matching call to CreateListenSocketIP on the specified port.
	///
	/// A SteamNetConnectionStatusChangedCallback_t callback will be triggered when we start
	/// connecting, and then another one on either timeout or successful connection.
	///
	/// If the server does not have any identity configured, then their network address
	/// will be the only identity in use.  Or, the network host may provide a platform-specific
	/// identity with or without a valid certificate to authenticate that identity.  (These
	/// details will be contained in the SteamNetConnectionStatusChangedCallback_t.)  It's
	/// up to your application to decide whether to allow the connection.
	///
	/// By default, all connections will get basic encryption sufficient to prevent
	/// casual eavesdropping.  But note that without certificates (or a shared secret
	/// distributed through some other out-of-band mechanism), you don't have any
	/// way of knowing who is actually on the other end, and thus are vulnerable to
	/// man-in-the-middle attacks.
	///
	/// If you need to set any initial config options, pass them here.  See
	/// SteamNetworkingConfigValue_t for more about why this is preferable to
	/// setting the options "immediately" after creation.
	virtual HSteamNetConnection ConnectByIPAddress( const SteamNetworkingIPAddr *address, int nOptions, const SteamNetworkingConfigValue_t *pOptions ) = 0;

#ifdef STEAMNETWORKINGSOCKETS_ENABLE_SDR
	/// Like CreateListenSocketIP, but clients will connect using ConnectP2P
	///
	/// nVirtualPort specifies how clients can connect to this socket using
	/// ConnectP2P.  It's very common for applications to only have one listening socket;
	/// in that case, use zero.  If you need to open multiple listen sockets and have clients
	/// be able to connect to one or the other, then nVirtualPort should be a small integer (<1000)
	/// unique to each listen socket you create.
	///
	/// If you use this, you probably want to call ISteamNetworkingUtils::InitRelayNetworkAccess()
	/// when your app initializes
	///
	/// If you need to set any initial config options, pass them here.  See
	/// SteamNetworkingConfigValue_t for more about why this is preferable to
	/// setting the options "immediately" after creation.
	virtual HSteamListenSocket CreateListenSocketP2P( int nVirtualPort, int nOptions, const SteamNetworkingConfigValue_t *pOptions ) = 0;

	/// Begin connecting to a server that is identified using a platform-specific identifier.
	/// This uses the default rendezvous service, which depends on the platform and library
	/// configuration.  (E.g. on Steam, it goes through the steam backend.)  The traffic is relayed
	/// over the Steam Datagram Relay network.
	///
	/// If you use this, you probably want to call ISteamNetworkingUtils::InitRelayNetworkAccess()
	/// when your app initializes
	///
	/// If you need to set any initial config options, pass them here.  See
	/// SteamNetworkingConfigValue_t for more about why this is preferable to
	/// setting the options "immediately" after creation.
	virtual HSteamNetConnection ConnectP2P( const SteamNetworkingIdentity *identityRemote, int nVirtualPort, int nOptions, const SteamNetworkingConfigValue_t *pOptions ) = 0;
#endif

	/// Accept an incoming connection that has been received on a listen socket.
	///
	/// When a connection attempt is received (perhaps after a few basic handshake
	/// packets have been exchanged to prevent trivial spoofing), a connection interface
	/// object is created in the k_ESteamNetworkingConnectionState_Connecting state
	/// and a SteamNetConnectionStatusChangedCallback_t is posted.  At this point, your
	/// application MUST either accept or close the connection.  (It may not ignore it.)
	/// Accepting the connection will transition it either into the connected state,
	/// or the finding route state, depending on the connection type.
	///
	/// You should take action within a second or two, because accepting the connection is
	/// what actually sends the reply notifying the client that they are connected.  If you
	/// delay taking action, from the client's perspective it is the same as the network
	/// being unresponsive, and the client may timeout the connection attempt.  In other
	/// words, the client cannot distinguish between a delay caused by network problems
	/// and a delay caused by the application.
	///
	/// This means that if your application goes for more than a few seconds without
	/// processing callbacks (for example, while loading a map), then there is a chance
	/// that a client may attempt to connect in that interval and fail due to timeout.
	///
	/// If the application does not respond to the connection attempt in a timely manner,
	/// and we stop receiving communication from the client, the connection attempt will
	/// be timed out locally, transitioning the connection to the
	/// k_ESteamNetworkingConnectionState_ProblemDetectedLocally state.  The client may also
	/// close the connection before it is accepted, and a transition to the
	/// k_ESteamNetworkingConnectionState_ClosedByPeer is also possible depending the exact
	/// sequence of events.
	///
	/// Returns k_EResultInvalidParam if the handle is invalid.
	/// Returns k_EResultInvalidState if the connection is not in the appropriate state.
	/// (Remember that the connection state could change in between the time that the
	/// notification being posted to the queue and when it is received by the application.)
	///
	/// A note about connection configuration options.  If you need to set any configuration
	/// options that are common to all connections accepted through a particular listen
	/// socket, consider setting the options on the listen socket, since such options are
	/// inherited automatically.  If you really do need to set options that are connection
	/// specific, it is safe to set them on the connection before accepting the connection.
	virtual EResult AcceptConnection( HSteamNetConnection hConn ) = 0;

	/// Disconnects from the remote host and invalidates the connection handle.
	/// Any unread data on the connection is discarded.
	///
	/// nReason is an application defined code that will be received on the other
	/// end and recorded (when possible) in backend analytics.  The value should
	/// come from a restricted range.  (See ESteamNetConnectionEnd.)  If you don't need
	/// to communicate any information to the remote host, and do not want analytics to
	/// be able to distinguish "normal" connection terminations from "exceptional" ones,
	/// You may pass zero, in which case the generic value of
	/// k_ESteamNetConnectionEnd_App_Generic will be used.
	///
	/// pszDebug is an optional human-readable diagnostic string that will be received
	/// by the remote host and recorded (when possible) in backend analytics.
	///
	/// If you wish to put the socket into a "linger" state, where an attempt is made to
	/// flush any remaining sent data, use bEnableLinger=true.  Otherwise reliable data
	/// is not flushed.
	///
	/// If the connection has already ended and you are just freeing up the
	/// connection interface, the reason code, debug string, and linger flag are
	/// ignored.
	virtual bool CloseConnection( HSteamNetConnection hPeer, int nReason, const char *pszDebug, bool bEnableLinger ) = 0;

	/// Destroy a listen socket.  All the connections that were accepting on the listen
	/// socket are closed ungracefully.
	virtual bool CloseListenSocket( HSteamListenSocket hSocket ) = 0;

	/// Set connection user data.  the data is returned in the following places
	/// - You can query it using GetConnectionUserData.
	/// - The SteamNetworkingmessage_t structure.
	/// - The SteamNetConnectionInfo_t structure.  (Which is a member of SteamNetConnectionStatusChangedCallback_t.)
	///
	/// Returns false if the handle is invalid.
	virtual bool SetConnectionUserData( HSteamNetConnection hPeer, int64 nUserData ) = 0;

	/// Fetch connection user data.  Returns -1 if handle is invalid
	/// or if you haven't set any userdata on the connection.
	virtual int64 GetConnectionUserData( HSteamNetConnection hPeer ) = 0;

	/// Set a name for the connection, used mostly for debugging
	virtual void SetConnectionName( HSteamNetConnection hPeer, const char *pszName ) = 0;

	/// Fetch connection name.  Returns false if handle is invalid
	virtual bool GetConnectionName( HSteamNetConnection hPeer, char *pszName, int nMaxLen ) = 0;

	/// Send a message to the remote host on the specified connection.
	///
	/// nSendFlags determines the delivery guarantees that will be provided,
	/// when data should be buffered, etc.  E.g. k_nSteamNetworkingSend_Unreliable
	///
	/// Note that the semantics we use for messages are not precisely
	/// the same as the semantics of a standard "stream" socket.
	/// (SOCK_STREAM)  For an ordinary stream socket, the boundaries
	/// between chunks are not considered relevant, and the sizes of
	/// the chunks of data written will not necessarily match up to
	/// the sizes of the chunks that are returned by the reads on
	/// the other end.  The remote host might read a partial chunk,
	/// or chunks might be coalesced.  For the message semantics 
	/// used here, however, the sizes WILL match.  Each send call 
	/// will match a successful read call on the remote host 
	/// one-for-one.  If you are porting existing stream-oriented 
	/// code to the semantics of reliable messages, your code should 
	/// work the same, since reliable message semantics are more 
	/// strict than stream semantics.  The only caveat is related to 
	/// performance: there is per-message overhead to retain the 
	/// message sizes, and so if your code sends many small chunks 
	/// of data, performance will suffer. Any code based on stream 
	/// sockets that does not write excessively small chunks will 
	/// work without any changes. 
	///
	/// The pOutMessageNumber is an optional pointer to receive the
	/// message number assigned to the message, if sending was successful.
	///
	/// Returns:
	/// - k_EResultInvalidParam: invalid connection handle, or the individual message is too big.
	///   (See k_cbMaxSteamNetworkingSocketsMessageSizeSend)
	/// - k_EResultInvalidState: connection is in an invalid state
	/// - k_EResultNoConnection: connection has ended
	/// - k_EResultIgnored: You used k_nSteamNetworkingSend_NoDelay, and the message was dropped because
	///   we were not ready to send it.
	/// - k_EResultLimitExceeded: there was already too much data queued to be sent.
	///   (See k_ESteamNetworkingConfig_SendBufferSize)
	virtual EResult SendMessageToConnection( HSteamNetConnection hConn, const void *pData, uint32 cbData, int nSendFlags, int64 *pOutMessageNumber ) = 0;

	/// Send one or more messages without copying the message payload.
	/// This is the most efficient way to send messages. To use this
	/// function, you must first allocate a message object using
	/// ISteamNetworkingUtils::AllocateMessage.  (Do not declare one
	/// on the stack or allocate your own.)
	///
	/// You should fill in the message payload.  You can either let
	/// it allocate the buffer for you and then fill in the payload,
	/// or if you already have a buffer allocated, you can just point
	/// m_pData at your buffer and set the callback to the appropriate function
	/// to free it.  Note that if you use your own buffer, it MUST remain valid
	/// until the callback is executed.  And also note that your callback can be
	/// invoked at ant time from any thread (perhaps even before SendMessages
	/// returns!), so it MUST be fast and threadsafe.
	///
	/// You MUST also fill in:
	/// - m_conn - the handle of the connection to send the message to
	/// - m_nFlags - bitmask of k_nSteamNetworkingSend_xxx flags.
	///
	/// All other fields are currently reserved and should not be modified.
	///
	/// The library will take ownership of the message structures.  They may
	/// be modified or become invalid at any time, so you must not read them
	/// after passing them to this function.
	///
	/// pOutMessageNumberOrResult is an optional array that will receive,
	/// for each message, the message number that was assigned to the message
	/// if sending was successful.  If sending failed, then a negative EResult
	/// valid is placed into the array.  For example, the array will hold
	/// -k_EResultInvalidState if the connection was in an invalid state.
	/// See ISteamNetworkingSockets::SendMessageToConnection for possible
	/// failure codes.
	virtual void SendMessages( int nMessages, SteamNetworkingMessage_t **pMessages, int64 *pOutMessageNumberOrResult ) = 0;

	/// Flush any messages waiting on the Nagle timer and send them
	/// at the next transmission opportunity (often that means right now).
	///
	/// If Nagle is enabled (it's on by default) then when calling 
	/// SendMessageToConnection the message will be buffered, up to the Nagle time
	/// before being sent, to merge small messages into the same packet.
	/// (See k_ESteamNetworkingConfig_NagleTime)
	///
	/// Returns:
	/// k_EResultInvalidParam: invalid connection handle
	/// k_EResultInvalidState: connection is in an invalid state
	/// k_EResultNoConnection: connection has ended
	/// k_EResultIgnored: We weren't (yet) connected, so this operation has no effect.
	virtual EResult FlushMessagesOnConnection( HSteamNetConnection hConn ) = 0;

	/// Fetch the next available message(s) from the connection, if any.
	/// Returns the number of messages returned into your array, up to nMaxMessages.
	/// If the connection handle is invalid, -1 is returned.
	///
	/// The order of the messages returned in the array is relevant.
	/// Reliable messages will be received in the order they were sent (and with the
	/// same sizes --- see SendMessageToConnection for on this subtle difference from a stream socket).
	///
	/// Unreliable messages may be dropped, or delivered out of order withrespect to
	/// each other or with respect to reliable messages.  The same unreliable message
	/// may be received multiple times.
	///
	/// If any messages are returned, you MUST call SteamNetworkingMessage_t::Release() on each
	/// of them free up resources after you are done.  It is safe to keep the object alive for
	/// a little while (put it into some queue, etc), and you may call Release() from any thread.
	virtual int ReceiveMessagesOnConnection( HSteamNetConnection hConn, SteamNetworkingMessage_t **ppOutMessages, int nMaxMessages ) = 0; 

	/// Same as ReceiveMessagesOnConnection, but will return the next message available
	/// on any connection that was accepted through the specified listen socket.  Examine
	/// SteamNetworkingMessage_t::m_conn to know which client connection.
	///
	/// Delivery order of messages among different clients is not defined.  They may
	/// be returned in an order different from what they were actually received.  (Delivery
	/// order of messages from the same client is well defined, and thus the order of the
	/// messages is relevant!)
	virtual int ReceiveMessagesOnListenSocket( HSteamListenSocket hSocket, SteamNetworkingMessage_t **ppOutMessages, int nMaxMessages ) = 0; 

	/// Returns basic information about the high-level state of the connection.
	virtual bool GetConnectionInfo( HSteamNetConnection hConn, SteamNetConnectionInfo_t *pInfo ) = 0;

	/// Returns a small set of information about the real-time state of the connection
	/// Returns false if the connection handle is invalid, or the connection has ended.
	virtual bool GetQuickConnectionStatus( HSteamNetConnection hConn, SteamNetworkingQuickConnectionStatus *pStats ) = 0;

	/// Returns detailed connection stats in text format.  Useful
	/// for dumping to a log, etc.
	///
	/// Returns:
	/// -1 failure (bad connection handle)
	/// 0 OK, your buffer was filled in and '\0'-terminated
	/// >0 Your buffer was either nullptr, or it was too small and the text got truncated.
	///    Try again with a buffer of at least N bytes.
	virtual int GetDetailedConnectionStatus( HSteamNetConnection hConn, char *pszBuf, int cbBuf ) = 0;

	/// Returns local IP and port that a listen socket created using CreateListenSocketIP is bound to.
	///
	/// An IPv6 address of ::0 means "any IPv4 or IPv6"
	/// An IPv6 address of ::ffff:0000:0000 means "any IPv4"
	virtual bool GetListenSocketAddress( HSteamListenSocket hSocket, SteamNetworkingIPAddr *address ) = 0;

	/// Create a pair of connections that are talking to each other, e.g. a loopback connection.
	/// This is very useful for testing, or so that your client/server code can work the same
	/// even when you are running a local "server".
	///
	/// The two connections will immediately be placed into the connected state, and no callbacks
	/// will be posted immediately.  After this, if you close either connection, the other connection
	/// will receive a callback, exactly as if they were communicating over the network.  You must
	/// close *both* sides in order to fully clean up the resources!
	///
	/// By default, internal buffers are used, completely bypassing the network, the chopping up of
	/// messages into packets, encryption, copying the payload, etc.  This means that loopback
	/// packets, by default, will not simulate lag or loss.  Passing true for bUseNetworkLoopback will
	/// cause the socket pair to send packets through the local network loopback device (127.0.0.1)
	/// on ephemeral ports.  Fake lag and loss are supported in this case, and CPU time is expended
	/// to encrypt and decrypt.
	///
	/// If you wish to assign a specific identity to either connection, you may pass a particular
	/// identity.  Otherwise, if you pass nullptr, the respective connection will assume a generic
	/// "localhost" identity.  If you use real network loopback, this might be translated to the
	/// actual bound loopback port.  Otherwise, the port will be zero.
	virtual bool CreateSocketPair( HSteamNetConnection *pOutConnection1, HSteamNetConnection *pOutConnection2, bool bUseNetworkLoopback, const SteamNetworkingIdentity *pIdentity1, const SteamNetworkingIdentity *pIdentity2 ) = 0;

	/// Get the identity assigned to this interface.
	/// E.g. on Steam, this is the user's SteamID, or for the gameserver interface, the SteamID assigned
	/// to the gameserver.  Returns false and sets the result to an invalid identity if we don't know
	/// our identity yet.  (E.g. GameServer has not logged in.  On Steam, the user will know their SteamID
	/// even if they are not signed into Steam.)
	virtual bool GetIdentity( SteamNetworkingIdentity *pIdentity ) = 0;

	/// Indicate our desire to be ready participate in authenticated communications.
	/// If we are currently not ready, then steps will be taken to obtain the necessary
	/// certificates.   (This includes a certificate for us, as well as any CA certificates
	/// needed to authenticate peers.)
	///
	/// You can call this at program init time if you know that you are going to
	/// be making authenticated connections, so that we will be ready immediately when
	/// those connections are attempted.  (Note that essentially all connections require
	/// authentication, with the exception of ordinary UDP connections with authentication
	/// disabled using k_ESteamNetworkingConfig_IP_AllowWithoutAuth.)  If you don't call
	/// this function, we will wait until a feature is utilized that that necessitates
	/// these resources.
	///
	/// You can also call this function to force a retry, if failure has occurred.
	/// Once we make an attempt and fail, we will not automatically retry.
	/// In this respect, the behavior of the system after trying and failing is the same
	/// as before the first attempt: attempting authenticated communication or calling
	/// this function will call the system to attempt to acquire the necessary resources.
	///
	/// You can use GetAuthenticationStatus or listen for SteamNetAuthenticationStatus_t
	/// to monitor the status.
	///
	/// Returns the current value that would be returned from GetAuthenticationStatus.
	virtual ESteamNetworkingAvailability InitAuthentication() = 0;

	/// Query our readiness to participate in authenticated communications.  A
	/// SteamNetAuthenticationStatus_t callback is posted any time this status changes,
	/// but you can use this function to query it at any time.
	///
	/// The value of SteamNetAuthenticationStatus_t::m_eAvail is returned.  If you only
	/// want this high level status, you can pass NULL for pDetails.  If you want further
	/// details, pass non-NULL to receive them.
	virtual ESteamNetworkingAvailability GetAuthenticationStatus( SteamNetAuthenticationStatus_t *pDetails ) = 0;

#ifdef STEAMNETWORKINGSOCKETS_ENABLE_SDR

	//
	// Clients connecting to dedicated servers hosted in a data center,
	// using central-authority-granted tickets.
	//

	/// Call this when you receive a ticket from your backend / matchmaking system.  Puts the
	/// ticket into a persistent cache, and optionally returns the parsed ticket.
	///
	/// See stamdatagram_ticketgen.h for more details.
	virtual bool ReceivedRelayAuthTicket( const void *pvTicket, int cbTicket, SteamDatagramRelayAuthTicket *pOutParsedTicket ) = 0;

	/// Search cache for a ticket to talk to the server on the specified virtual port.
	/// If found, returns the number of seconds until the ticket expires, and optionally
	/// the complete cracked ticket.  Returns 0 if we don't have a ticket.
	///
	/// Typically this is useful just to confirm that you have a ticket, before you
	/// call ConnectToHostedDedicatedServer to connect to the server.
	virtual int FindRelayAuthTicketForServer( const SteamNetworkingIdentity *identityGameServer, int nVirtualPort, SteamDatagramRelayAuthTicket *pOutParsedTicket ) = 0;

	/// Client call to connect to a server hosted in a Valve data center, on the specified virtual
	/// port.  You must have placed a ticket for this server into the cache, or else this connect attempt will fail!
	///
	/// You may wonder why tickets are stored in a cache, instead of simply being passed as an argument
	/// here.  The reason is to make reconnection to a gameserver robust, even if the client computer loses
	/// connection to Steam or the central backend, or the app is restarted or crashes, etc.
	///
	/// If you use this, you probably want to call ISteamNetworkingUtils::InitRelayNetworkAccess()
	/// when your app initializes
	///
	/// If you need to set any initial config options, pass them here.  See
	/// SteamNetworkingConfigValue_t for more about why this is preferable to
	/// setting the options "immediately" after creation.
	virtual HSteamNetConnection ConnectToHostedDedicatedServer( const SteamNetworkingIdentity *identityTarget, int nVirtualPort, int nOptions, const SteamNetworkingConfigValue_t *pOptions ) = 0;

	//
	// Servers hosted in data centers known to the Valve relay network
	//

	/// Returns the value of the SDR_LISTEN_PORT environment variable.  This
	/// is the UDP server your server will be listening on.  This will
	/// configured automatically for you in production environments.
	///
	/// In development, you'll need to set it yourself.  See
	/// https://partner.steamgames.com/doc/api/ISteamNetworkingSockets
	/// for more information on how to configure dev environments.
	virtual uint16 GetHostedDedicatedServerPort() = 0;

	/// Returns 0 if SDR_LISTEN_PORT is not set.  Otherwise, returns the data center the server
	/// is running in.  This will be k_SteamDatagramPOPID_dev in non-production envirionment.
	virtual SteamNetworkingPOPID GetHostedDedicatedServerPOPID() = 0;

	/// Return info about the hosted server.  This contains the PoPID of the server,
	/// and opaque routing information that can be used by the relays to send traffic
	/// to your server.
	///
	/// You will need to send this information to your backend, and put it in tickets,
	/// so that the relays will know how to forward traffic from
	/// clients to your server.  See SteamDatagramRelayAuthTicket for more info.
	///
	/// Also, note that the routing information is contained in SteamDatagramGameCoordinatorServerLogin,
	/// so if possible, it's preferred to use GetGameCoordinatorServerLogin to send this info
	/// to your game coordinator service, and also login securely at the same time.
	///
	/// On a successful exit, k_EResultOK is returned
	///
	/// Unsuccessful exit:
	/// - Something other than k_EResultOK is returned.
	/// - k_EResultInvalidState: We are not configured to listen for SDR (SDR_LISTEN_SOCKET
	///   is not set.)
	/// - k_EResultPending: we do not (yet) have the authentication information needed.
	///   (See GetAuthenticationStatus.)  If you use environment variables to pre-fetch
	///   the network config, this data should always be available immediately.
	/// - A non-localized diagnostic debug message will be placed in m_data that describes
	///   the cause of the failure.
	///
	/// NOTE: The returned blob is not encrypted.  Send it to your backend, but don't
	///       directly share it with clients.
	virtual EResult GetHostedDedicatedServerAddress( SteamDatagramHostedAddress *pRouting ) = 0;

	/// Create a listen socket on the specified virtual port.  The physical UDP port to use
	/// will be determined by the SDR_LISTEN_PORT environment variable.  If a UDP port is not
	/// configured, this call will fail.
	///
	/// Note that this call MUST be made through the SteamGameServerNetworkingSockets() interface
	///
	/// If you need to set any initial config options, pass them here.  See
	/// SteamNetworkingConfigValue_t for more about why this is preferable to
	/// setting the options "immediately" after creation.
	virtual HSteamListenSocket CreateHostedDedicatedServerListenSocket( int nVirtualPort, int nOptions, const SteamNetworkingConfigValue_t *pOptions ) = 0;

	/// Generate an authentication blob that can be used to securely login with
	/// your backend, using SteamDatagram_ParseHostedServerLogin.  (See
	/// steamdatagram_gamecoordinator.h)
	///
	/// Before calling the function:
	/// - Populate the app data in pLoginInfo (m_cbAppData and m_appData).  You can leave
	///   all other fields uninitialized.
	/// - *pcbSignedBlob contains the size of the buffer at pBlob.  (It should be
	///   at least k_cbMaxSteamDatagramGameCoordinatorServerLoginSerialized.)
	///
	/// On a successful exit:
	/// - k_EResultOK is returned
	/// - All of the remaining fields of pLoginInfo will be filled out.
	/// - *pcbSignedBlob contains the size of the serialized blob that has been
	///   placed into pBlob.
	///
	/// Unsuccessful exit:
	/// - Something other than k_EResultOK is returned.
	/// - k_EResultNotLoggedOn: you are not logged in (yet)
	/// - See GetHostedDedicatedServerAddress for more potential failure return values.
	/// - A non-localized diagnostic debug message will be placed in pBlob that describes
	///   the cause of the failure.
	///
	/// This works by signing the contents of the SteamDatagramGameCoordinatorServerLogin
	/// with the cert that is issued to this server.  In dev environments, it's OK if you do
	/// not have a cert.  (You will need to enable insecure dev login in SteamDatagram_ParseHostedServerLogin.)
	/// Otherwise, you will need a signed cert.
	///
	/// NOTE: The routing blob returned here is not encrypted.  Send it to your backend
	///       and don't share it directly with clients.
	virtual EResult GetGameCoordinatorServerLogin( SteamDatagramGameCoordinatorServerLogin *pLoginInfo, int *pcbSignedBlob, void *pBlob ) = 0;


	//
	// Relayed connections using custom signaling protocol
	//
	// This is used if you have your own method of sending out-of-band
	// signaling / rendezvous messages through a mutually trusted channel.
	//

	/// Create a P2P "client" connection that does signaling over a custom
	/// rendezvous/signaling channel.
	///
	/// pSignaling points to a new object that you create just for this connection.
	/// It must stay valid until Release() is called.  Once you pass the
	/// object to this function, it assumes ownership.  Release() will be called
	/// from within the function call if the call fails.  Furthermore, until Release()
	/// is called, you should be prepared for methods to be invoked on your
	/// object from any thread!  You need to make sure your object is threadsafe!
	/// Furthermore, you should make sure that dispatching the methods is done
	/// as quickly as possible.
	///
	/// This function will immediately construct a connection in the "connecting"
	/// state.  Soon after (perhaps before this function returns, perhaps in another thread),
	/// the connection will begin sending signaling messages by calling
	/// ISteamNetworkingConnectionCustomSignaling::SendSignal.
	///
	/// When the remote peer accepts the connection (See
	/// ISteamNetworkingCustomSignalingRecvContext::OnConnectRequest),
	/// it will begin sending signaling messages.  When these messages are received,
	/// you can pass them to the connection using ReceivedP2PCustomSignal.
	///
	/// If you know the identity of the peer that you expect to be on the other end,
	/// you can pass their identity to improve debug output or just detect bugs.
	/// If you don't know their identity yet, you can pass NULL, and their
	/// identity will be established in the connection handshake.  
	///
	/// If you use this, you probably want to call ISteamNetworkingUtils::InitRelayNetworkAccess()
	/// when your app initializes
	///
	/// If you need to set any initial config options, pass them here.  See
	/// SteamNetworkingConfigValue_t for more about why this is preferable to
	/// setting the options "immediately" after creation.
	virtual HSteamNetConnection ConnectP2PCustomSignaling( ISteamNetworkingConnectionCustomSignaling *pSignaling, const SteamNetworkingIdentity *pPeerIdentity, int nOptions, const SteamNetworkingConfigValue_t *pOptions ) = 0;

	/// Called when custom signaling has received a message.  When your
	/// signaling channel receives a message, it should save off whatever
	/// routing information was in the envelope into the context object,
	/// and then pass the payload to this function.
	///
	/// A few different things can happen next, depending on the message:
	///
	/// - If the signal is associated with existing connection, it is dealt
	///   with immediately.  If any replies need to be sent, they will be
	///   dispatched using the ISteamNetworkingConnectionCustomSignaling
	///   associated with the connection.
	/// - If the message represents a connection request (and the request
	///   is not redundant for an existing connection), a new connection
	///   will be created, and ReceivedConnectRequest will be called on your
	///   context object to determine how to proceed.
	/// - Otherwise, the message is for a connection that does not
	///   exist (anymore).  In this case, we *may* call SendRejectionReply
	///   on your context object.
	///
	/// In any case, we will not save off pContext or access it after this
	/// function returns.
	///
	/// Returns true if the message was parsed and dispatched without anything
	/// unusual or suspicious happening.  Returns false if there was some problem
	/// with the message that prevented ordinary handling.  (Debug output will
	/// usually have more information.)
	///
	/// If you expect to be using relayed connections, then you probably want
	/// to call ISteamNetworkingUtils::InitRelayNetworkAccess() when your app initializes
	virtual bool ReceivedP2PCustomSignal( const void *pMsg, int cbMsg, ISteamNetworkingCustomSignalingRecvContext *pContext ) = 0;
#endif // #ifndef STEAMNETWORKINGSOCKETS_ENABLE_SDR

/// Certificate provision by the application.  (On Steam, Steam will handle all this automatically)
#ifndef STEAMNETWORKINGSOCKETS_STEAM

	/// Get blob that describes a certificate request.  You can send this to your game coordinator.
	/// Upon entry, *pcbBlob should contain the size of the buffer.  On successful exit, it will
	/// return the number of bytes that were populated.  You can pass pBlob=NULL to query for the required
	/// size.  (256 bytes is a very conservative estimate.)
	///
	/// Pass this blob to your game coordinator and call SteamDatagram_CreateCert.
	virtual bool GetCertificateRequest( int *pcbBlob, void *pBlob, SteamNetworkingErrMsg *errMsg ) = 0;

	/// Set the certificate.  The certificate blob should be the output of
	/// SteamDatagram_CreateCert.
	virtual bool SetCertificate( const void *pCertificate, int cbCertificate, SteamNetworkingErrMsg *errMsg ) = 0;
#endif

	// Invoke all callbacks queued for this interface.
	// On Steam, callbacks are dispatched via the ordinary Steamworks callbacks mechanism.
	// So if you have code that is also targeting Steam, you should call this at about the
	// same time you would call SteamAPI_RunCallbacks and SteamGameServer_RunCallbacks.
#ifdef STEAMNETWORKINGSOCKETS_STANDALONELIB
	virtual void RunCallbacks( ISteamNetworkingSocketsCallbacks *pCallbacks ) = 0;
#endif
protected:
	~ISteamNetworkingSockets(); // Silence some warnings
};
#define STEAMNETWORKINGSOCKETS_INTERFACE_VERSION "SteamNetworkingSockets006"

/// Interface used to send signaling messages for a particular connection.
/// You will need to construct one of these per connection.
///
/// - For connections initiated locally, you will construct it and pass
///   it to ISteamNetworkingSockets::ConnectP2PCustomSignaling.
/// - For connections initiated remotely and "accepted" locally, you
///   will return it from ISteamNetworkingCustomSignalingRecvContext::OnConnectRequest
class ISteamNetworkingConnectionCustomSignaling
{
public:
	/// Called to send a rendezvous message to the remote peer.  This may be called
	/// from any thread, at any time, so you need to be thread-safe!  Don't take
	/// any locks that might hold while calling into SteamNetworkingSockets functions,
	/// because this could lead to deadlocks.
	///
	/// Note that when initiating a connection, we may not know the identity
	/// of the peer, if you did not specify it in ConnectP2PCustomSignaling.
	///
	/// Return true if a best-effort attempt was made to deliver the message.
	/// If you return false, it is assumed that the situation is fatal;
	/// the connection will be closed, and Release() will be called
	/// eventually.
	///
	/// Signaling objects will not be shared between connections.
	/// You can assume that the same value of hConn will be used
	/// every time.
	virtual bool SendSignal( HSteamNetConnection hConn, const SteamNetConnectionInfo_t *info, const void *pMsg, int cbMsg ) = 0;

	/// Called when the connection no longer needs to send signals.
	/// Note that this happens eventually (but not immediately) after
	/// the connection is closed.  Signals may need to be sent for a brief
	/// time after the connection is closed, to clean up the connection.
	virtual void Release() = 0;
};

/// Interface used when a custom signal is received.
/// See ISteamNetworkingSockets::ReceivedP2PCustomSignal
class ISteamNetworkingCustomSignalingRecvContext
{
public:

	/// Called when the signal represents a request for a new connection.
	///
	/// If you want to ignore the request, just return NULL.  In this case,
	/// the peer will NOT receive any reply.  You should consider ignoring
	/// requests rather than actively rejecting them, as a security measure.
	/// If you actively reject requests, then this makes it possible to detect
	/// if a user is online or not, just by sending them a request.
	///
	/// If you wish to send back a rejection, then use
	/// ISteamNetworkingSockets::CloseConnection() and then return NULL.
	/// We will marshal a properly formatted rejection signal and
	/// call SendRejectionSignal() so you can send it to them.
	///
	/// If you return a signaling object, the connection is NOT immediately
	/// accepted by default.  Instead, it stays in the "connecting" state,
	/// and the usual callback is posted, and your app can accept the
	/// connection using ISteamNetworkingSockets::AcceptConnection.  This
	/// may be useful so that these sorts of connections can be more similar
	/// to your application code as other types of connections accepted on
	/// a listen socket.  If this is not useful and you want to skip this
	/// callback process and immediately accept the connection, call
	/// ISteamNetworkingSockets::AcceptConnection before returning the
	/// signaling object.
	///
	/// After accepting a connection (through either means), the connection
	/// will transition into the "finding route" state.
	virtual ISteamNetworkingConnectionCustomSignaling *OnConnectRequest( HSteamNetConnection hConn, const SteamNetworkingIdentity *identityPeer ) = 0;

	/// This is called actively communication rejection or failure
	/// to the incoming message.  If you intend to ignore all incoming requests
	/// that you do not wish to accept, then it's not strictly necessary to
	/// implement this.
	virtual void SendRejectionSignal( const SteamNetworkingIdentity *identityPeer, const void *pMsg, int cbMsg ) = 0;
};


extern "C" {

// Global accessor.
#if defined( STEAMNETWORKINGSOCKETS_PARTNER )

	// Standalone lib.  Use different symbol name, so that we can dynamically switch between steamclient.dll
	// and the standalone lib
	STEAMNETWORKINGSOCKETS_INTERFACE ISteamNetworkingSockets *SteamNetworkingSockets_Lib();
	STEAMNETWORKINGSOCKETS_INTERFACE ISteamNetworkingSockets *SteamGameServerNetworkingSockets_Lib();
	inline ISteamNetworkingSockets *SteamNetworkingSockets() { return SteamNetworkingSockets_Lib(); }
	inline ISteamNetworkingSockets *SteamGameServerNetworkingSockets() { return SteamGameServerNetworkingSockets_Lib(); }

#elif defined( STEAMNETWORKINGSOCKETS_OPENSOURCE ) || defined( STEAMNETWORKINGSOCKETS_STREAMINGCLIENT )

	// Opensource GameNetworkingSockets
	STEAMNETWORKINGSOCKETS_INTERFACE ISteamNetworkingSockets *SteamNetworkingSockets();

#else

	// Steamworks SDK
	inline ISteamNetworkingSockets *SteamNetworkingSockets();
	STEAM_DEFINE_USER_INTERFACE_ACCESSOR( ISteamNetworkingSockets *, SteamNetworkingSockets, STEAMNETWORKINGSOCKETS_INTERFACE_VERSION );
	inline ISteamNetworkingSockets *SteamGameServerNetworkingSockets();
	STEAM_DEFINE_GAMESERVER_INTERFACE_ACCESSOR( ISteamNetworkingSockets *, SteamGameServerNetworkingSockets, STEAMNETWORKINGSOCKETS_INTERFACE_VERSION );
#endif

}

/// Callback struct used to notify when a connection has changed state
#if defined( VALVE_CALLBACK_PACK_SMALL )
#pragma pack( push, 4 )
#elif defined( VALVE_CALLBACK_PACK_LARGE )
#pragma pack( push, 8 )
#else
#error "Must define VALVE_CALLBACK_PACK_SMALL or VALVE_CALLBACK_PACK_LARGE"
#endif

/// This callback is posted whenever a connection is created, destroyed, or changes state.
/// The m_info field will contain a complete description of the connection at the time the
/// change occurred and the callback was posted.  In particular, m_eState will have the
/// new connection state.
///
/// You will usually need to listen for this callback to know when:
/// - A new connection arrives on a listen socket.
///   m_info.m_hListenSocket will be set, m_eOldState = k_ESteamNetworkingConnectionState_None,
///   and m_info.m_eState = k_ESteamNetworkingConnectionState_Connecting.
///   See ISteamNetworkigSockets::AcceptConnection.
/// - A connection you initiated has been accepted by the remote host.
///   m_eOldState = k_ESteamNetworkingConnectionState_Connecting, and
///   m_info.m_eState = k_ESteamNetworkingConnectionState_Connected.
///   Some connections might transition to k_ESteamNetworkingConnectionState_FindingRoute first.
/// - A connection has been actively rejected or closed by the remote host.
///   m_eOldState = k_ESteamNetworkingConnectionState_Connecting or k_ESteamNetworkingConnectionState_Connected,
///   and m_info.m_eState = k_ESteamNetworkingConnectionState_ClosedByPeer.  m_info.m_eEndReason
///   and m_info.m_szEndDebug will have for more details.
///   NOTE: upon receiving this callback, you must still destroy the connection using
///   ISteamNetworkingSockets::CloseConnection to free up local resources.  (The details
///   passed to the function are not used in this case, since the connection is already closed.)
/// - A problem was detected with the connection, and it has been closed by the local host.
///   The most common failure is timeout, but other configuration or authentication failures
///   can cause this.  m_eOldState = k_ESteamNetworkingConnectionState_Connecting or
///   k_ESteamNetworkingConnectionState_Connected, and m_info.m_eState = k_ESteamNetworkingConnectionState_ProblemDetectedLocally.
///   m_info.m_eEndReason and m_info.m_szEndDebug will have for more details.
///   NOTE: upon receiving this callback, you must still destroy the connection using
///   ISteamNetworkingSockets::CloseConnection to free up local resources.  (The details
///   passed to the function are not used in this case, since the connection is already closed.)
///
/// Remember that callbacks are posted to a queue, and networking connections can
/// change at any time.  It is possible that the connection has already changed
/// state by the time you process this callback.
///
/// Also note that callbacks will be posted when connections are created and destroyed by your own API calls.
struct SteamNetConnectionStatusChangedCallback_t
{ 
	enum { k_iCallback = k_iSteamNetworkingSocketsCallbacks + 1 };

	/// Connection handle
	HSteamNetConnection m_hConn;

	/// Full connection info
	SteamNetConnectionInfo_t m_info;

	/// Previous state.  (Current state is in m_info.m_eState)
	ESteamNetworkingConnectionState m_eOldState;
};

/// A struct used to describe our readiness to participate in authenticated,
/// encrypted communication.  In order to do this we need:
///
/// - The list of trusted CA certificates that might be relevant for this
///   app.
/// - A valid certificate issued by a CA.
///
/// This callback is posted whenever the state of our readiness changes.
struct SteamNetAuthenticationStatus_t
{ 
	enum { k_iCallback = k_iSteamNetworkingSocketsCallbacks + 2 };

	/// Status
	ESteamNetworkingAvailability m_eAvail;

	/// Non-localized English language status.  For diagnostic/debugging
	/// purposes only.
	char m_debugMsg[ 256 ];
};

#pragma pack( pop )


#endif // ISTEAMNETWORKINGSOCKETS