ServerFull Packet Implementation (#889)

* Implement ServerFullPacket including server side handling and a place holder client side.

* Making suggested edits to move to an empty packet

Co-authored-by: Stephen Horan <steve.horan@theatsgroup.com>

d2networking/d2client/game_client.go

@@ -156,6 +156,9 @@ func (g *GameClient) OnPacketReceived(packet d2netpacket.NetPacket) error {
 		// https://github.com/OpenDiablo2/OpenDiablo2/issues/802
 		log.Print("Server has been closed")
 		os.Exit(0)
+	case d2netpackettype.ServerFull:
+		log.Println("Server is full")
+		os.Exit(0)
 	default:
 		log.Fatalf("Invalid packet type: %d", packet.PacketType)
 	}

d2networking/d2netpacket/d2netpackettype/message_type.go

@@ -31,6 +31,7 @@ const (
 	CastSkill                                            // Sent by client or server, indicates entity casting skill
 	SpawnItem                                            // Sent by server
 	SavePlayer                                           // Sent by the client, saves the player
+	ServerFull                                           // Sent by server when server has reached max connections
 
 	UnknownPacketType = 666
 )
@@ -49,6 +50,7 @@ func (n NetPacketType) String() string {
 		CastSkill:                       "CastSkill",
 		SpawnItem:                       "SpawnItem",
 		SavePlayer:                      "SavePlayer",
+		ServerFull:                      "ServerFull",
 	}
 
 	return strings[n]

d2networking/d2netpacket/packet_server_full.go

@@ -0,0 +1,38 @@
+package d2netpacket
+
+import (
+	"encoding/json"
+	"log"
+
+	"github.com/OpenDiablo2/OpenDiablo2/d2networking/d2netpacket/d2netpackettype"
+)
+
+// ServerFullPacket is sent by the server to inform a client that the
+// server has reached the max number of allowed connections.
+type ServerFullPacket struct{}
+
+// CreateServerFullPacket returns a NetPacket which declares a ServerFullPacket.
+func CreateServerFullPacket() NetPacket {
+	serverClosed := ServerFullPacket{}
+
+	b, err := json.Marshal(serverClosed)
+	if err != nil {
+		log.Print(err)
+	}
+
+	return NetPacket{
+		PacketType: d2netpackettype.ServerFull,
+		PacketData: b,
+	}
+}
+
+// UnmarshalServerFull unmarshalls the given data to a ServerFullPacket struct
+func UnmarshalServerFull(packet []byte) (ServerFullPacket, error) {
+	var resp ServerFullPacket
+
+	if err := json.Unmarshal(packet, &resp); err != nil {
+		return resp, err
+	}
+
+	return resp, nil
+}

d2networking/d2server/game_server.go

@@ -246,13 +246,13 @@ func (g *GameServer) handleConnection(conn net.Conn) {
 			if err := g.registerConnection(packet.PacketData, conn); err != nil {
 				switch err {
 				case errServerFull: // Server is currently full and not accepting new connections.
-					// https://github.com/OpenDiablo2/OpenDiablo2/issues/828
-					log.Println(err)
-					return
+					_, errServerFullPacket := conn.Write(d2netpacket.MarshalPacket(d2netpacket.CreateServerFullPacket()))
+					log.Println(errServerFullPacket)
 				case errPlayerAlreadyExists: // Player is already registered and did not disconnection correctly.
 					log.Println(err)
-					return
 				}
+
+				return
 			}
 
 			connected = 1