allow changing packet sharing behavior in old p2p networking via ini config

dll/dll/p2p_manager.hpp

@@ -18,6 +18,7 @@
 #pragma once
 
 #include "base.h"
+#include <tuple>
 
 
 class P2p_Manager
@@ -31,8 +32,15 @@ private:
 
     struct Packet_t
     {
+    private:
+        std::chrono::high_resolution_clock::time_point time_created = std::chrono::high_resolution_clock::now();
+
+    public:
         bool is_processed = false;
         std::vector<char> data{};
+        EP2PSend send_type = EP2PSend::k_EP2PSendUnreliable;
+
+        const std::chrono::high_resolution_clock::time_point& get_time_created() const;
     };
 
     struct Channel_t
@@ -69,7 +77,17 @@ private:
 
     // true if the connection was already accepted,
     // false otherwise.
-    bool store_packet(CSteamID my_id, CSteamID steamIDRemote, const void *pubData, uint32 cubData, int nChannel);
+    bool store_packet(
+        CSteamID my_id, CSteamID steamIDRemote,
+        const void *pubData, uint32 cubData, int nChannel,
+        EP2PSend send_type
+    );
+
+    std::optional<std::tuple<
+        decltype(connections)::iterator,
+        decltype(Connection_t::channels)::iterator,
+        decltype(Channel_t::packets)::iterator
+    >> get_next_packet(CSteamID my_id, int nChannel);
 
     void periodic_handle_connections(const std::chrono::high_resolution_clock::time_point &now);
     void periodic_handle_channels(const std::chrono::high_resolution_clock::time_point &now);

dll/dll/settings.h

@@ -200,6 +200,32 @@ struct Branch_Info {
     bool active = false;
 };
 
+struct OldP2pBehavior {
+    enum class EPacketShareMode {
+        // if the sending type is unreliable (UDP), share packets between gameserver and client
+        // otherwise, don't share packets
+        DEFAULT,
+
+        // always share packets between gameserver and client
+        ALWAYS_SHARE,
+
+        // never share packets between gameserver and client
+        NEVER_SHARE,
+
+        _LAST,
+    };
+
+    static EPacketShareMode to_share_mode(int val) {
+        if (val < 0 || val >= (unsigned)EPacketShareMode::_LAST) {
+            return EPacketShareMode::DEFAULT;
+        }
+
+        return (EPacketShareMode)val;
+    }
+
+    EPacketShareMode mode = EPacketShareMode::DEFAULT;
+};
+
 class Settings {
 private:
     CSteamID steam_id{}; // user id
@@ -373,6 +399,9 @@ public:
     // free weekend
     bool free_weekend = false;
 
+    // old P2P (ISteamNetworking) behavior
+    OldP2pBehavior old_p2p_behavior{};
+
     // voice chat
     bool enable_voice_chat = false;
 

dll/net.proto

@@ -81,15 +81,15 @@ message Low_Level {
 }
 
 message Network_pb {
-    int32 channel = 1;
-    bytes data = 2;
-
     enum Types {
         DATA = 0;
         FAILED_CONNECT = 1;
     }
 
-    Types type = 3;
+    Types type = 1;
+    int32 channel = 2;
+    bytes data = 3;
+    uint32 send_type = 4; // EP2PSend
 }
 
 message Network_Old {

dll/p2p_manager.cpp

@@ -28,6 +28,14 @@ constexpr static double SESSION_REQUEST_DELAY = 2.0;
 // "if we can't get through to the user after a timeout of 20 seconds, then an error will be posted"
 constexpr static double SESSION_REQUEST_TIMEOUT = 20.0;
 
+constexpr static double PACKET_MAX_TIME_TO_LIVE = 20.0;
+
+
+
+const std::chrono::high_resolution_clock::time_point& P2p_Manager::Packet_t::get_time_created() const
+{
+    return time_created;
+}
 
 
 void P2p_Manager::steam_networking_callback(void *object, Common_Message *msg)
@@ -196,7 +204,11 @@ P2p_Manager::~P2p_Manager()
 }
 
 
-bool P2p_Manager::store_packet(CSteamID my_id, CSteamID steamIDRemote, const void *pubData, uint32 cubData, int nChannel)
+bool P2p_Manager::store_packet(
+    CSteamID my_id, CSteamID steamIDRemote,
+    const void *pubData, uint32 cubData, int nChannel,
+    EP2PSend send_type
+)
 {
     std::lock_guard lock(p2p_mtx);
 
@@ -205,6 +217,7 @@ bool P2p_Manager::store_packet(CSteamID my_id, CSteamID steamIDRemote, const voi
     {
         Packet_t channel_msg{};
         channel_msg.is_processed = conn->is_accepted;
+        channel_msg.send_type = send_type;
         if (pubData && cubData > 0) {
             channel_msg.data.assign((const char *)pubData, (const char *)pubData + cubData);
         }
@@ -221,11 +234,91 @@ bool P2p_Manager::store_packet(CSteamID my_id, CSteamID steamIDRemote, const voi
     return conn->is_accepted;
 }
 
+std::optional<std::tuple<
+    decltype(P2p_Manager::connections)::iterator,
+    decltype(P2p_Manager::Connection_t::channels)::iterator,
+    decltype(P2p_Manager::Channel_t::packets)::iterator
+>> P2p_Manager::get_next_packet(CSteamID my_id, int nChannel)
+{
+    const auto my_settings = is_same_peer(my_id, settings_client->get_local_steam_id())
+        ? settings_client
+        : settings_server;
+
+    for (auto conn_it = connections.begin(); connections.end() != conn_it; ++conn_it) {
+        if (!conn_it->is_accepted) {
+            continue;
+        }
+
+        auto ch_it = conn_it->channels.find(nChannel);
+        // channel doesn't exist for this connection
+        if (conn_it->channels.end() == ch_it) {
+            continue;
+        }
+
+        auto &packets = ch_it->second.packets;
+        auto packet_it = packets.begin();
+        // channel has no packets
+        if (packets.end() == packet_it) {
+            continue;
+        }
+
+        // no need to check next packets in this channel if the first one isn't processed yet
+        // once the connection is accepted, all messages in all channels will be marked  as processed
+        if (!packet_it->is_processed) {
+            continue;
+        }
+
+        const bool is_packet_for_me = is_same_peer(my_id, conn_it->peer_conn.my_dest_id);
+        if (!is_packet_for_me) {
+            bool can_share_packet = false;
+
+            switch (my_settings->old_p2p_behavior.mode) {
+            default:
+            case OldP2pBehavior::EPacketShareMode::DEFAULT: {
+                // appids (353090, 301300) do this:
+                // - send packet from client >>> to gameserver
+                // - use the **client** to check for these packets
+                // it should use the gameserver instead
+                // but the client is expected to return these packets to the game
+                // this seems to be an old behavior
+                //
+                // on the contrary appids (701160, 248390) use k_EP2PSendReliable
+                // and they do not need the gameserver to share its packets with the client
+                // even multiplayer in appid 248390 won't work if packets were shared
+                can_share_packet =
+                    packet_it->send_type == EP2PSend::k_EP2PSendUnreliable ||
+                    packet_it->send_type == EP2PSend::k_EP2PSendUnreliableNoDelay;
+            }
+            break;
+
+            case OldP2pBehavior::EPacketShareMode::ALWAYS_SHARE: {
+                can_share_packet = true;
+            }
+            break;
+            
+            case OldP2pBehavior::EPacketShareMode::NEVER_SHARE: {
+                can_share_packet = false;
+            }
+            break;
+            }
+
+            // avoid sharing packets between client and gameserver
+            if (!can_share_packet) {
+                continue;
+            }
+        }
+
+        return std::make_tuple(conn_it, ch_it, packet_it);
+    }
+
+    return {};
+}
+
 
 bool P2p_Manager::send_packet(CSteamID my_id, CSteamID steamIDRemote, const void *pubData, uint32 cubData, EP2PSend eP2PSendType, int nChannel)
 {
     bool reliable = false;
-    if (eP2PSendType == k_EP2PSendReliable || eP2PSendType == k_EP2PSendReliableWithBuffering) {
+    if (eP2PSendType == EP2PSend::k_EP2PSendReliable || eP2PSendType == EP2PSend::k_EP2PSendReliableWithBuffering) {
         reliable = true;
     }
 
@@ -257,6 +350,7 @@ bool P2p_Manager::send_packet(CSteamID my_id, CSteamID steamIDRemote, const void
     msg.mutable_network()->set_type(Network_pb::DATA);
     msg.mutable_network()->set_channel(nChannel);
     msg.mutable_network()->set_data(pubData, cubData);
+    msg.mutable_network()->set_send_type(eP2PSendType);
 
     bool ret = false;
     {
@@ -281,31 +375,22 @@ bool P2p_Manager::is_packet_available(CSteamID my_id, uint32 *pcubMsgSize, int n
 
     if (pcubMsgSize) *pcubMsgSize = 0;
 
-    for (const auto &conn : connections) {
-        if (!conn.is_accepted) {
-            continue;
-        }
-
-        auto ch_it = conn.channels.find(nChannel);
-        if (conn.channels.end() == ch_it) {
-            continue;
-        }
-
-        auto msg_it = ch_it->second.packets.begin();
-        if (ch_it->second.packets.end() != msg_it) {
-            if (msg_it->is_processed) {
-                uint32 size = static_cast<uint32>(msg_it->data.size());
-                if (pcubMsgSize) {
-                    *pcubMsgSize = size;
-                }
-                PRINT_DEBUG("  available message from=[%llu], size=[%u]", conn.peer_conn.remote_id.ConvertToUint64(), size);
-                
-                return true;
-            }
-        }
+    auto packet_opt = get_next_packet(my_id, nChannel);
+    if (!packet_opt) {
+        return false;
     }
 
-    return false;
+    auto &[conn_it, ch_it, packet_it] = packet_opt.value();
+    uint32 size = static_cast<uint32>(packet_it->data.size());
+    if (pcubMsgSize) {
+        *pcubMsgSize = size;
+    }
+    PRINT_DEBUG(
+        "  available message from=[%llu], size=[%u]",
+        conn_it->peer_conn.remote_id.ConvertToUint64(), size
+    );
+    
+    return true;
 }
 
 bool P2p_Manager::read_packet(CSteamID my_id, void *pubDest, uint32 cubDest, uint32 *pcubMsgSize, CSteamID *psteamIDRemote, int nChannel)
@@ -315,49 +400,39 @@ bool P2p_Manager::read_packet(CSteamID my_id, void *pubDest, uint32 cubDest, uin
     if (pcubMsgSize) *pcubMsgSize = 0;
     if (psteamIDRemote) *psteamIDRemote = k_steamIDNil;
 
-    bool read = false;
-    for (auto &conn : connections) {
-        if (!conn.is_accepted) {
-            continue;
-        }
-
-        auto ch_it = conn.channels.find(nChannel);
-        if (conn.channels.end() == ch_it) {
-            continue;
-        }
-
-        auto msg_it = ch_it->second.packets.begin();
-        if (ch_it->second.packets.end() != msg_it) {
-            if (msg_it->is_processed) {
-                if (psteamIDRemote) {
-                    *psteamIDRemote = conn.peer_conn.remote_id;
-                }
-
-                uint32 size = static_cast<uint32>(msg_it->data.size());
-                if (cubDest < size) {
-                    // https://partner.steamgames.com/doc/api/ISteamNetworking#ReadP2PPacket
-                    // "If the cubDest buffer is too small for the packet, then the message will be truncated"
-                    size = cubDest;
-                }
-
-                if (pcubMsgSize) {
-                    *pcubMsgSize = size;
-                }
-
-                if (pubDest) {
-                    memcpy(pubDest, msg_it->data.data(), size);
-                }
-
-                ch_it->second.packets.erase(msg_it);
-
-                PRINT_DEBUG("  copied message from=[%llu], size=[%u]", conn.peer_conn.remote_id.ConvertToUint64(), size);
-                
-                return true;
-            }
-        }
+    auto packet_opt = get_next_packet(my_id, nChannel);
+    if (!packet_opt) {
+        return false;
     }
 
-    return false;
+    auto &[conn_it, ch_it, packet_it] = packet_opt.value();
+    if (psteamIDRemote) {
+        *psteamIDRemote = conn_it->peer_conn.remote_id;
+    }
+
+    uint32 size = static_cast<uint32>(packet_it->data.size());
+    if (cubDest < size) {
+        // https://partner.steamgames.com/doc/api/ISteamNetworking#ReadP2PPacket
+        // "If the cubDest buffer is too small for the packet, then the message will be truncated"
+        size = cubDest;
+    }
+
+    if (pcubMsgSize) {
+        *pcubMsgSize = size;
+    }
+
+    if (pubDest) {
+        memcpy(pubDest, packet_it->data.data(), size);
+    }
+
+    ch_it->second.packets.erase(packet_it);
+
+    PRINT_DEBUG(
+        "  copied message from=[%llu], size=[%u]",
+        conn_it->peer_conn.remote_id.ConvertToUint64(), size
+    );
+
+    return true;
 }
 
 bool P2p_Manager::close_channel(CSteamID my_id, CSteamID steamIDRemote, int nChannel)
@@ -436,9 +511,9 @@ bool P2p_Manager::get_session_state(CSteamID my_id, CSteamID steamIDRemote, P2PS
         if (pConnectionState) {
             int32 pending_packets = 0;
             int32 pending_bytes = 0;
-            for (auto& [ch_idx, channel] : conn->channels) {
+            for (const auto& [ch_idx, channel] : conn->channels) {
                 pending_packets += (int32)channel.packets.size();
-                for (auto &msg : channel.packets) {
+                for (const auto &msg : channel.packets) {
                     pending_bytes += (int32)msg.data.size();
                 }
             }
@@ -488,14 +563,18 @@ bool P2p_Manager::accept_session(CSteamID my_id, CSteamID steamIDRemote)
 
 void P2p_Manager::periodic_handle_connections(const std::chrono::high_resolution_clock::time_point &now)
 {
-    for (auto conn_it = connections.begin(); connections.end() != conn_it; ) {
+    auto conn_it = connections.begin();
+    while (connections.end() != conn_it) {
+        bool is_remove = false;
         if (!conn_it->is_accepted) {
             if (check_timedout(conn_it->time_added, SESSION_REQUEST_TIMEOUT, now)) {
+                is_remove = true;
                 send_peer_session_failure(conn_it->peer_conn);
-                conn_it = connections.erase(conn_it);
-            } else {
-                ++conn_it;
             }
+        }
+
+        if (is_remove) {
+            conn_it = connections.erase(conn_it);
         } else {
             ++conn_it;
         }
@@ -509,10 +588,15 @@ void P2p_Manager::periodic_handle_channels(const std::chrono::high_resolution_cl
             continue;
         }
 
+        // remove channels with no packets
         auto ch_it = conn.channels.begin();
         while (conn.channels.end() != ch_it) {
-            // TODO anything channel related goes here
-            ++ch_it;
+            auto &channel = ch_it->second;
+            if (channel.packets.empty()) {
+                ch_it = conn.channels.erase(ch_it);
+            } else {
+                ++ch_it;
+            }
         }
     }
 }
@@ -524,9 +608,22 @@ void P2p_Manager::periodic_handle_packets(const std::chrono::high_resolution_clo
             continue;
         }
 
-        for (auto& [ch_num, channel] : conn.channels) {
-            for (auto &msg : channel.packets) {
-                msg.is_processed = true;
+        for (auto &[ch_num, channel] : conn.channels) {
+            // remove outadated packets, and mark the rest as processed
+            auto packet_it = channel.packets.begin();
+            while (channel.packets.end() != packet_it) {
+                bool is_remove = false;
+                if (check_timedout(packet_it->get_time_created(), PACKET_MAX_TIME_TO_LIVE, now)) {
+                    is_remove = true;
+                } else {
+                    packet_it->is_processed = true;
+                }
+
+                if (is_remove) {
+                    packet_it = channel.packets.erase(packet_it);
+                } else {
+                    ++packet_it;
+                }
             }
         }
     }
@@ -548,22 +645,23 @@ void P2p_Manager::periodic_callback()
 void P2p_Manager::network_data_packets(Common_Message *msg)
 {
     const CSteamID src_id = (uint64)msg->source_id();
-    const CSteamID dest_id = (uint64)msg->dest_id(); // this is us
+    const CSteamID my_dest_id = (uint64)msg->dest_id(); // this is us
 
     PRINT_DEBUG("got network msg from [%llu], I am [%llu], type <%u>",
-        src_id.ConvertToUint64(), dest_id.ConvertToUint64(), msg->network().type()
+        src_id.ConvertToUint64(), my_dest_id.ConvertToUint64(), msg->network().type()
     );
 
     switch (msg->network().type()) {
     case Network_pb::DATA: {
         PRINT_DEBUG("got network data message");
         const bool conn_is_accepted = store_packet(
-            dest_id, src_id,
+            my_dest_id, src_id,
             msg->network().data().c_str(), (uint32)msg->network().data().size(),
-            (int)msg->network().channel()
+            (int)msg->network().channel(),
+            (EP2PSend)msg->network().send_type()
         );
         if (!conn_is_accepted) {
-            trigger_session_request(src_id, dest_id);
+            trigger_session_request(src_id, my_dest_id);
         }
     }
     break;
@@ -574,13 +672,13 @@ void P2p_Manager::network_data_packets(Common_Message *msg)
         data.m_steamIDRemote = src_id;
         data.m_eP2PSessionError = EP2PSessionError::k_EP2PSessionErrorTimeout;
 
-        get_my_callbacks(dest_id)->addCBResult(data.k_iCallback, &data, sizeof(data));
+        get_my_callbacks(my_dest_id)->addCBResult(data.k_iCallback, &data, sizeof(data));
 
         {
             std::lock_guard lock(p2p_mtx);
 
-            remove_connection(src_id, dest_id);
-            remove_connection(dest_id, src_id);
+            remove_connection(src_id, my_dest_id);
+            remove_connection(my_dest_id, src_id);
         }
     }
     break;
@@ -590,7 +688,7 @@ void P2p_Manager::network_data_packets(Common_Message *msg)
 void P2p_Manager::network_low_level(Common_Message *msg)
 {
     const CSteamID src_id = (uint64)msg->source_id();
-    const CSteamID dest_id = (uint64)msg->dest_id(); // this is us
+    const CSteamID my_dest_id = (uint64)msg->dest_id(); // this is us
 
     switch (msg->low_level().type()) {
         case Low_Level::CONNECT: {
@@ -603,20 +701,20 @@ void P2p_Manager::network_low_level(Common_Message *msg)
             {
                 std::lock_guard lock(p2p_mtx);
 
-                any_conn_removed |= remove_connection(src_id, dest_id);
-                any_conn_removed |= remove_connection(dest_id, src_id);
+                any_conn_removed |= remove_connection(src_id, my_dest_id);
+                any_conn_removed |= remove_connection(my_dest_id, src_id);
             }
 
             if (any_conn_removed) {
                 PRINT_DEBUG(
                     "[X] remote user [%llu] disconnected, sending P2PSessionConnectFail_t, I am [%llu]",
-                    src_id.ConvertToUint64(), dest_id.ConvertToUint64()
+                    src_id.ConvertToUint64(), my_dest_id.ConvertToUint64()
                 );
                 P2PSessionConnectFail_t data{};
                 data.m_steamIDRemote = src_id;
                 data.m_eP2PSessionError = k_EP2PSessionErrorDestinationNotLoggedIn;
 
-                get_my_callbacks(dest_id)->addCBResult(data.k_iCallback, &data, sizeof(data));
+                get_my_callbacks(my_dest_id)->addCBResult(data.k_iCallback, &data, sizeof(data));
             }
 
         }

dll/settings_parser.cpp

@@ -1583,6 +1583,13 @@ static void parse_simple_features(class Settings *settings_client, class Setting
     settings_client->download_steamhttp_requests = ini.GetBoolValue("main::connectivity", "download_steamhttp_requests", settings_client->download_steamhttp_requests);
     settings_server->download_steamhttp_requests = ini.GetBoolValue("main::connectivity", "download_steamhttp_requests", settings_server->download_steamhttp_requests);
 
+    settings_client->old_p2p_behavior.mode = OldP2pBehavior::to_share_mode(
+        (int)ini.GetLongValue("main::connectivity", "old_p2p_packet_sharing_mode", (unsigned)settings_client->old_p2p_behavior.mode)
+    );
+    settings_server->old_p2p_behavior.mode = OldP2pBehavior::to_share_mode(
+        (int)ini.GetLongValue("main::connectivity", "old_p2p_packet_sharing_mode", (unsigned)settings_server->old_p2p_behavior.mode)
+    );
+
 
     // [main::misc]
     settings_client->achievement_bypass = ini.GetBoolValue("main::misc", "achievements_bypass", settings_client->achievement_bypass);

post_build/steam_settings.EXAMPLE/configs.main.EXAMPLE.ini

@@ -125,6 +125,19 @@ disable_lobby_creation=0
 # this will **not** work if the app is using native/OS web APIs
 # default=0
 download_steamhttp_requests=0
+# sharing mode of the old P2P networking interface (ISteamNetworking).
+# this defines how the gameserver and the client intances can read P2P packets received from other players.
+#
+# some older games require sharing the received packets, i.e if the gameserver instance received a packet,
+# then the client instance should be able to detect/read it as well.
+# other games won't work properly if the packets were shared,
+# and the original receiver (either gameserver or client) must handle that packet
+#
+# 0=share packets flagged as "unreliable" (k_EP2PSendUnreliable | k_EP2PSendUnreliableNoDelay), otherwise don't share packets
+# 1=always share the packets
+# 2=never share the packets
+# default=0
+old_p2p_packet_sharing_mode=0
 
 # mostly workarounds for specific problems
 [main::misc]