Allow DSCP tagging and local traffic prioritization to be enabled separately on Mac and Linux

src/platform/common.h

@@ -608,8 +608,17 @@ namespace platf {
     audio,
     video
   };
+
+  /**
+   * @brief Enables QoS on the given socket for traffic to the specified destination.
+   * @param native_socket The native socket handle.
+   * @param address The destination address for traffic sent on this socket.
+   * @param port The destination port for traffic sent on this socket.
+   * @param data_type The type of traffic sent on this socket.
+   * @param dscp_tagging Specifies whether to enable DSCP tagging on outgoing traffic.
+   */
   std::unique_ptr<deinit_t>
-  enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type);
+  enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type, bool dscp_tagging);
 
   /**
    * @brief Open a url in the default web browser.

src/platform/linux/misc.cpp

@@ -586,59 +586,92 @@ namespace platf {
 
   class qos_t: public deinit_t {
   public:
-    qos_t(int sockfd, int level, int option):
+    qos_t(int sockfd, std::vector<std::tuple<int, int, int>> options):
-        sockfd(sockfd), level(level), option(option) {}
+        sockfd(sockfd), options(options) {}
 
     virtual ~qos_t() {
-      int reset_val = -1;
+      for (const auto &tuple : options) {
-      if (setsockopt(sockfd, level, option, &reset_val, sizeof(reset_val)) < 0) {
+        auto reset_val = std::get<2>(tuple);
-        BOOST_LOG(warning) << "Failed to reset IP TOS: "sv << errno;
+        if (setsockopt(sockfd, std::get<0>(tuple), std::get<1>(tuple), &reset_val, sizeof(reset_val)) < 0) {
+          BOOST_LOG(warning) << "Failed to reset option: "sv << errno;
+        }
       }
     }
 
   private:
     int sockfd;
-    int level;
+    std::vector<std::tuple<int, int, int>> options;
-    int option;
   };
 
+  /**
+   * @brief Enables QoS on the given socket for traffic to the specified destination.
+   * @param native_socket The native socket handle.
+   * @param address The destination address for traffic sent on this socket.
+   * @param port The destination port for traffic sent on this socket.
+   * @param data_type The type of traffic sent on this socket.
+   * @param dscp_tagging Specifies whether to enable DSCP tagging on outgoing traffic.
+   */
   std::unique_ptr<deinit_t>
-  enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type) {
+  enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type, bool dscp_tagging) {
     int sockfd = (int) native_socket;
+    std::vector<std::tuple<int, int, int>> reset_options;
 
-    int level;
+    if (dscp_tagging) {
-    int option;
+      int level;
-    if (address.is_v6()) {
+      int option;
-      level = SOL_IPV6;
+      if (address.is_v6()) {
-      option = IPV6_TCLASS;
+        level = SOL_IPV6;
+        option = IPV6_TCLASS;
+      }
+      else {
+        level = SOL_IP;
+        option = IP_TOS;
+      }
+
+      // The specific DSCP values here are chosen to be consistent with Windows
+      int dscp = 0;
+      switch (data_type) {
+        case qos_data_type_e::video:
+          dscp = 40;
+          break;
+        case qos_data_type_e::audio:
+          dscp = 56;
+          break;
+        default:
+          BOOST_LOG(error) << "Unknown traffic type: "sv << (int) data_type;
+          break;
+      }
+
+      if (dscp) {
+        // Shift to put the DSCP value in the correct position in the TOS field
+        dscp <<= 2;
+
+        if (setsockopt(sockfd, level, option, &dscp, sizeof(dscp)) == 0) {
+          // Reset TOS to -1 when QoS is disabled
+          reset_options.emplace_back(std::make_tuple(level, option, -1));
+        }
+        else {
+          BOOST_LOG(error) << "Failed to set TOS/TCLASS: "sv << errno;
+        }
+      }
+    }
+
+    // We can use SO_PRIORITY to set outgoing traffic priority without DSCP tagging.
+    //
+    // NB: We set this after IP_TOS/IPV6_TCLASS since setting TOS value seems to
+    // reset SO_PRIORITY back to 0.
+    //
+    // 6 is the highest priority that can be used without SYS_CAP_ADMIN.
+    int priority = data_type == qos_data_type_e::audio ? 6 : 5;
+    if (setsockopt(sockfd, SOL_SOCKET, SO_PRIORITY, &priority, sizeof(priority)) == 0) {
+      // Reset SO_PRIORITY to 0 when QoS is disabled
+      reset_options.emplace_back(std::make_tuple(SOL_SOCKET, SO_PRIORITY, 0));
     }
     else {
-      level = SOL_IP;
+      BOOST_LOG(error) << "Failed to set SO_PRIORITY: "sv << errno;
-      option = IP_TOS;
     }
 
-    // The specific DSCP values here are chosen to be consistent with Windows
+    return std::make_unique<qos_t>(sockfd, reset_options);
-    int dscp;
-    switch (data_type) {
-      case qos_data_type_e::video:
-        dscp = 40;
-        break;
-      case qos_data_type_e::audio:
-        dscp = 56;
-        break;
-      default:
-        BOOST_LOG(error) << "Unknown traffic type: "sv << (int) data_type;
-        return nullptr;
-    }
-
-    // Shift to put the DSCP value in the correct position in the TOS field
-    dscp <<= 2;
-
-    if (setsockopt(sockfd, level, option, &dscp, sizeof(dscp)) < 0) {
-      return nullptr;
-    }
-
-    return std::make_unique<qos_t>(sockfd, level, option);
   }
 
   namespace source {

src/platform/macos/misc.mm

@@ -407,12 +407,103 @@ namespace platf {
     return true;
   }
 
+  class qos_t: public deinit_t {
+  public:
+    qos_t(int sockfd, std::vector<std::tuple<int, int, int>> options):
+        sockfd(sockfd), options(options) {}
+
+    virtual ~qos_t() {
+      for (const auto &tuple : options) {
+        auto reset_val = std::get<2>(tuple);
+        if (setsockopt(sockfd, std::get<0>(tuple), std::get<1>(tuple), &reset_val, sizeof(reset_val)) < 0) {
+          BOOST_LOG(warning) << "Failed to reset option: "sv << errno;
+        }
+      }
+    }
+
+  private:
+    int sockfd;
+    std::vector<std::tuple<int, int, int>> options;
+  };
+
+  /**
+   * @brief Enables QoS on the given socket for traffic to the specified destination.
+   * @param native_socket The native socket handle.
+   * @param address The destination address for traffic sent on this socket.
+   * @param port The destination port for traffic sent on this socket.
+   * @param data_type The type of traffic sent on this socket.
+   * @param dscp_tagging Specifies whether to enable DSCP tagging on outgoing traffic.
+   */
   std::unique_ptr<deinit_t>
-  enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type) {
+  enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type, bool dscp_tagging) {
-    // Unimplemented
+    int sockfd = (int) native_socket;
-    //
+    std::vector<std::tuple<int, int, int>> reset_options;
-    // NB: When implementing, remember to consider that some routes can drop DSCP-tagged packets completely!
+
-    return nullptr;
+    // We can use SO_NET_SERVICE_TYPE to set link-layer prioritization without DSCP tagging
+    int service_type = 0;
+    switch (data_type) {
+      case qos_data_type_e::video:
+        service_type = NET_SERVICE_TYPE_VI;
+        break;
+      case qos_data_type_e::audio:
+        service_type = NET_SERVICE_TYPE_VO;
+        break;
+      default:
+        BOOST_LOG(error) << "Unknown traffic type: "sv << (int) data_type;
+        break;
+    }
+
+    if (service_type) {
+      if (setsockopt(sockfd, SOL_SOCKET, SO_NET_SERVICE_TYPE, &service_type, sizeof(service_type)) == 0) {
+        // Reset SO_NET_SERVICE_TYPE to best-effort when QoS is disabled
+        reset_options.emplace_back(std::make_tuple(SOL_SOCKET, SO_NET_SERVICE_TYPE, NET_SERVICE_TYPE_BE));
+      }
+      else {
+        BOOST_LOG(error) << "Failed to set SO_NET_SERVICE_TYPE: "sv << errno;
+      }
+    }
+
+    if (dscp_tagging) {
+      int level;
+      int option;
+      if (address.is_v6()) {
+        level = IPPROTO_IPV6;
+        option = IPV6_TCLASS;
+      }
+      else {
+        level = IPPROTO_IP;
+        option = IP_TOS;
+      }
+
+      // The specific DSCP values here are chosen to be consistent with Windows
+      int dscp = 0;
+      switch (data_type) {
+        case qos_data_type_e::video:
+          dscp = 40;
+          break;
+        case qos_data_type_e::audio:
+          dscp = 56;
+          break;
+        default:
+          BOOST_LOG(error) << "Unknown traffic type: "sv << (int) data_type;
+          break;
+      }
+
+      if (dscp) {
+        // Shift to put the DSCP value in the correct position in the TOS field
+        dscp <<= 2;
+
+        if (setsockopt(sockfd, level, option, &dscp, sizeof(dscp)) == 0) {
+          // Reset TOS to -1 when QoS is disabled
+          reset_options.emplace_back(std::make_tuple(level, option, -1));
+        }
+        else {
+          BOOST_LOG(error) << "Failed to set TOS/TCLASS: "sv << errno;
+        }
+      }
+    }
+
+    return std::make_unique<qos_t>(sockfd, reset_options);
   }
 
 }  // namespace platf

src/platform/windows/misc.cpp

@@ -1209,13 +1209,26 @@ namespace platf {
     QOS_FLOWID flow_id;
   };
 
+  /**
+   * @brief Enables QoS on the given socket for traffic to the specified destination.
+   * @param native_socket The native socket handle.
+   * @param address The destination address for traffic sent on this socket.
+   * @param port The destination port for traffic sent on this socket.
+   * @param data_type The type of traffic sent on this socket.
+   * @param dscp_tagging Specifies whether to enable DSCP tagging on outgoing traffic.
+   */
   std::unique_ptr<deinit_t>
-  enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type) {
+  enable_socket_qos(uintptr_t native_socket, boost::asio::ip::address &address, uint16_t port, qos_data_type_e data_type, bool dscp_tagging) {
     SOCKADDR_IN saddr_v4;
     SOCKADDR_IN6 saddr_v6;
     PSOCKADDR dest_addr;
     bool using_connect_hack = false;
 
+    // Windows doesn't support any concept of traffic priority without DSCP tagging
+    if (!dscp_tagging) {
+      return nullptr;
+    }
+
     static std::once_flag load_qwave_once_flag;
     std::call_once(load_qwave_once_flag, []() {
       // qWAVE is not installed by default on Windows Server, so we load it dynamically

src/stream.cpp

@@ -1740,12 +1740,10 @@ namespace stream {
       return;
     }
 
-    // Enable QoS tagging on video traffic if requested by the client
+    // Enable local prioritization and QoS tagging on video traffic if requested by the client
-    if (session->config.videoQosType) {
+    auto address = session->video.peer.address();
-      auto address = session->video.peer.address();
+    session->video.qos = platf::enable_socket_qos(ref->video_sock.native_handle(), address,
-      session->video.qos = platf::enable_socket_qos(ref->video_sock.native_handle(), address,
+      session->video.peer.port(), platf::qos_data_type_e::video, session->config.videoQosType != 0);
-        session->video.peer.port(), platf::qos_data_type_e::video);
-    }
 
     BOOST_LOG(debug) << "Start capturing Video"sv;
     video::capture(session->mail, session->config.monitor, session);
@@ -1765,12 +1763,10 @@ namespace stream {
       return;
     }
 
-    // Enable QoS tagging on audio traffic if requested by the client
+    // Enable local prioritization and QoS tagging on audio traffic if requested by the client
-    if (session->config.audioQosType) {
+    auto address = session->audio.peer.address();
-      auto address = session->audio.peer.address();
+    session->audio.qos = platf::enable_socket_qos(ref->audio_sock.native_handle(), address,
-      session->audio.qos = platf::enable_socket_qos(ref->audio_sock.native_handle(), address,
+      session->audio.peer.port(), platf::qos_data_type_e::audio, session->config.audioQosType != 0);
-        session->audio.peer.port(), platf::qos_data_type_e::audio);
-    }
 
     BOOST_LOG(debug) << "Start capturing Audio"sv;
     audio::capture(session->mail, session->config.audio, session);