Added error reporting when a player is not allowed to play.

network/netplay/README

@@ -214,6 +214,14 @@ Description:
     players the frame number must be later than the last frame of the relevant
     player's input that has been transmitted.
 
+Command: MODE_REFUSED
+Payload:
+    {
+       reason: uint32
+    }
+Description:
+    Inform a client that its request to change modes has been refused.
+
 Command: CRC
 Payload:
     {

network/netplay/netplay_io.c

@@ -588,7 +588,12 @@ static bool netplay_get_cmd(netplay_t *netplay,
             return netplay_cmd_nak(netplay, connection);
 
          if (!connection->can_play)
+         {
+            /* Not allowed to play */
+            payload[0] = htonl(NETPLAY_CMD_MODE_REFUSED_REASON_UNPRIVILEGED);
+            netplay_send_raw_cmd(netplay, connection, NETPLAY_CMD_MODE_REFUSED, payload, sizeof(uint32_t));
             break;
+         }
 
          /* Find an available player slot */
          for (player = 0; player <= netplay->player_max; player++)
@@ -600,7 +605,9 @@ static bool netplay_get_cmd(netplay_t *netplay,
          }
          if (player > netplay->player_max)
          {
-            /* Sorry, you can't play! */
+            /* No slots free! */
+            payload[0] = htonl(NETPLAY_CMD_MODE_REFUSED_REASON_NO_SLOTS);
+            netplay_send_raw_cmd(netplay, connection, NETPLAY_CMD_MODE_REFUSED, payload, sizeof(uint32_t));
             break;
          }
 
@@ -780,6 +787,37 @@ static bool netplay_get_cmd(netplay_t *netplay,
 #undef NEXT
       }
 
+      case NETPLAY_CMD_MODE_REFUSED:
+         {
+            uint32_t reason;
+            char msg[512];
+
+            if (cmd_size != sizeof(uint32_t))
+               return netplay_cmd_nak(netplay, connection);
+
+            RECV(&reason, sizeof(reason))
+               return netplay_cmd_nak(netplay, connection);
+            reason = ntohl(reason);
+
+            switch (reason)
+            {
+               case NETPLAY_CMD_MODE_REFUSED_REASON_UNPRIVILEGED:
+                  strlcpy(msg, "You do not have permission to play.", sizeof(msg));
+                  break;
+
+               case NETPLAY_CMD_MODE_REFUSED_REASON_NO_SLOTS:
+                  strlcpy(msg, "There are no free player slots.", sizeof(msg));
+                  break;
+
+               default:
+                  strlcpy(msg, "Cannot switch to play mode.", sizeof(msg));
+            }
+
+            RARCH_LOG("%s\n", msg);
+            runloop_msg_queue_push(msg, 1, 180, false);
+            break;
+         }
+
       case NETPLAY_CMD_DISCONNECT:
          netplay_hangup(netplay, connection);
          return true;

network/netplay/netplay_private.h

@@ -121,6 +121,9 @@ enum netplay_cmd
    /* Report player mode */
    NETPLAY_CMD_MODE           = 0x0025,
 
+   /* Report player mode refused */
+   NETPLAY_CMD_MODE_REFUSED   = 0x0026,
+
    /* Loading and synchronization */
 
    /* Send the CRC hash of a frame's state */
@@ -160,6 +163,19 @@ enum netplay_cmd
 #define NETPLAY_CMD_MODE_BIT_PLAYING   (1U<<17)
 #define NETPLAY_CMD_MODE_BIT_YOU       (1U<<16)
 
+/* These are the reasons given for mode changes to be rejected */
+enum netplay_cmd_mode_reasons
+{
+   /* Other/unknown reason */
+   NETPLAY_CMD_MODE_REFUSED_REASON_OTHER,
+
+   /* You don't have permission to play */
+   NETPLAY_CMD_MODE_REFUSED_REASON_UNPRIVILEGED,
+
+   /* There are no free player slots */
+   NETPLAY_CMD_MODE_REFUSED_REASON_NO_SLOTS
+};
+
 /* These are the configurations sent by NETPLAY_CMD_CFG. */
 enum netplay_cmd_cfg
 {