NetworkIdentity.cs

using System;
using System.Collections.Generic;
using System.Collections.ObjectModel;
using System.Linq;
using UnityEngine;

#if UNITY_EDITOR
using UnityEditor;
#endif

namespace Mirror
{
    [ExecuteInEditMode]
    [DisallowMultipleComponent]
    [AddComponentMenu("Network/NetworkIdentity")]
    public sealed class NetworkIdentity : MonoBehaviour
    {
        // configuration
        [SerializeField] NetworkSceneId m_SceneId;
        [SerializeField] NetworkHash128 m_AssetId;
        [SerializeField] bool           m_ServerOnly;
        [SerializeField] bool           m_LocalPlayerAuthority;

        // runtime data
        bool                        m_IsClient;
        bool                        m_IsServer;
        bool                        m_HasAuthority;

        NetworkInstanceId           m_NetId;
        bool                        m_IsLocalPlayer;
        NetworkConnection           m_ConnectionToServer;
        NetworkConnection           m_ConnectionToClient;
        NetworkBehaviour[]          m_NetworkBehaviours;

        // there is a list AND a hashSet of connections, for fast verification of dupes, but the main operation is iteration over the list.
        HashSet<int>                m_ObserverConnections;
        List<NetworkConnection>     m_Observers;
        NetworkConnection           m_ClientAuthorityOwner;

        // member used to mark a identity for future reset
        // check MarkForReset for more information.
        bool                        m_Reset = false;
        // properties
        public bool isClient        { get { return m_IsClient; } }
        public bool isServer        { get { return m_IsServer && NetworkServer.active; } } // dont return true if server stopped.
        public bool hasAuthority    { get { return m_HasAuthority; } }

        public NetworkInstanceId netId { get { return m_NetId; } }
        public NetworkSceneId sceneId { get { return m_SceneId; } }
        public bool serverOnly { get { return m_ServerOnly; } set { m_ServerOnly = value; } }
        public bool localPlayerAuthority { get { return m_LocalPlayerAuthority; } set { m_LocalPlayerAuthority = value; } }
        public NetworkConnection clientAuthorityOwner { get { return m_ClientAuthorityOwner; }}

        public NetworkHash128 assetId
        {
            get
            {
#if UNITY_EDITOR
                // This is important because sometimes OnValidate does not run (like when adding view to prefab with no child links)
                if (!m_AssetId.IsValid())
                    SetupIDs();
#endif
                return m_AssetId;
            }
        }
        internal void SetDynamicAssetId(NetworkHash128 newAssetId)
        {
            if (!m_AssetId.IsValid() || m_AssetId.Equals(newAssetId))
            {
                m_AssetId = newAssetId;
            }
            else
            {
                if (LogFilter.logWarn) { Debug.LogWarning("SetDynamicAssetId object already has an assetId <" + m_AssetId + ">"); }
            }
        }

        // used when adding players
        internal void SetClientOwner(NetworkConnection conn)
        {
            if (m_ClientAuthorityOwner != null)
            {
                if (LogFilter.logError) { Debug.LogError("SetClientOwner m_ClientAuthorityOwner already set!"); }
            }
            m_ClientAuthorityOwner = conn;
            m_ClientAuthorityOwner.AddOwnedObject(this);
        }

        // used during dispose after disconnect
        internal void ClearClientOwner()
        {
            m_ClientAuthorityOwner = null;
        }

        internal void ForceAuthority(bool authority)
        {
            if (m_HasAuthority == authority)
            {
                return;
            }

            m_HasAuthority = authority;
            if (authority)
            {
                OnStartAuthority();
            }
            else
            {
                OnStopAuthority();
            }
        }

        public bool isLocalPlayer { get { return m_IsLocalPlayer; } }
        public NetworkConnection connectionToServer { get { return m_ConnectionToServer; } }
        public NetworkConnection connectionToClient { get { return m_ConnectionToClient; } }

        public ReadOnlyCollection<NetworkConnection> observers
        {
            get
            {
                return m_Observers != null ? new ReadOnlyCollection<NetworkConnection>(m_Observers) : null;
            }
        }

        static uint s_NextNetworkId = 1;
        internal static NetworkInstanceId GetNextNetworkId()
        {
            return new NetworkInstanceId(s_NextNetworkId++);
        }

        void CacheBehaviours()
        {
            if (m_NetworkBehaviours == null)
            {
                m_NetworkBehaviours = GetComponents<NetworkBehaviour>();
            }
        }

        public delegate void ClientAuthorityCallback(NetworkConnection conn, NetworkIdentity uv, bool authorityState);
        public static ClientAuthorityCallback clientAuthorityCallback;

        internal static void AddNetworkId(uint id)
        {
            if (id >= s_NextNetworkId)
            {
                s_NextNetworkId = (uint)(id + 1);
            }
        }

        // only used during spawning on clients to set the identity.
        internal void SetNetworkInstanceId(NetworkInstanceId newNetId)
        {
            m_NetId = newNetId;
            if (newNetId.Value == 0)
            {
                m_IsServer = false;
            }
        }

        // only used when fixing duplicate scene IDs duing post-processing
        public void ForceSceneId(int newSceneId)
        {
            m_SceneId = new NetworkSceneId((uint)newSceneId);
        }

        // only used in SetLocalObject
        internal void UpdateClientServer(bool isClientFlag, bool isServerFlag)
        {
            m_IsClient |= isClientFlag;
            m_IsServer |= isServerFlag;
        }

        // used when the player object for a connection changes
        internal void SetNotLocalPlayer()
        {
            m_IsLocalPlayer = false;

            if (NetworkServer.active && NetworkServer.localClientActive)
            {
                // dont change authority for objects on the host
                return;
            }
            m_HasAuthority = false;
        }

        // this is used when a connection is destroyed, since the "observers" property is read-only
        internal void RemoveObserverInternal(NetworkConnection conn)
        {
            if (m_Observers != null)
            {
                m_Observers.Remove(conn);
                m_ObserverConnections.Remove(conn.connectionId);
            }
        }

#if UNITY_EDITOR
        void OnValidate()
        {
            if (m_ServerOnly && m_LocalPlayerAuthority)
            {
                if (LogFilter.logWarn) { Debug.LogWarning("Disabling Local Player Authority for " + gameObject + " because it is server-only."); }
                m_LocalPlayerAuthority = false;
            }

            SetupIDs();
        }

        void AssignAssetID(GameObject prefab)
        {
            string path = AssetDatabase.GetAssetPath(prefab);
            m_AssetId = NetworkHash128.Parse(AssetDatabase.AssetPathToGUID(path));
        }

        bool ThisIsAPrefab()
        {
            PrefabType prefabType = PrefabUtility.GetPrefabType(gameObject);
            if (prefabType == PrefabType.Prefab)
                return true;
            return false;
        }

        bool ThisIsASceneObjectWithPrefabParent(out GameObject prefab)
        {
            prefab = null;
            PrefabType prefabType = PrefabUtility.GetPrefabType(gameObject);
            if (prefabType == PrefabType.None)
                return false;
            prefab = (GameObject)PrefabUtility.GetPrefabParent(gameObject);
            if (prefab == null)
            {
                if (LogFilter.logError) { Debug.LogError("Failed to find prefab parent for scene object [name:" + gameObject.name + "]"); }
                return false;
            }
            return true;
        }

        void SetupIDs()
        {
            GameObject prefab;
            if (ThisIsAPrefab())
            {
                ForceSceneId(0);
                AssignAssetID(gameObject);
            }
            else if (ThisIsASceneObjectWithPrefabParent(out prefab))
            {
                AssignAssetID(prefab);
            }
            else
            {
                m_AssetId = new NetworkHash128();
            }
        }

#endif
        void OnDestroy()
        {
            if (m_IsServer && NetworkServer.active)
            {
                NetworkServer.Destroy(gameObject);
            }
        }

        internal void OnStartServer(bool allowNonZeroNetId)
        {
            if (m_IsServer)
            {
                return;
            }
            m_IsServer = true;
            m_HasAuthority = !m_LocalPlayerAuthority;

            m_Observers = new List<NetworkConnection>();
            m_ObserverConnections = new HashSet<int>();
            CacheBehaviours();

            // If the instance/net ID is invalid here then this is an object instantiated from a prefab and the server should assign a valid ID
            if (netId.IsEmpty())
            {
                m_NetId = GetNextNetworkId();
            }
            else
            {
                if (!allowNonZeroNetId)
                {
                    if (LogFilter.logError) { Debug.LogError("Object has non-zero netId " + netId + " for " + gameObject); }
                    return;
                }
            }

            if (LogFilter.logDev) { Debug.Log("OnStartServer " + gameObject + " GUID:" + netId); }
            NetworkServer.SetLocalObjectOnServer(netId, gameObject);

            for (int i = 0; i < m_NetworkBehaviours.Length; i++)
            {
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                try
                {
                    comp.OnStartServer();
                }
                catch (Exception e)
                {
                    Debug.LogError("Exception in OnStartServer:" + e.Message + " " + e.StackTrace);
                }
            }

            if (NetworkClient.active && NetworkServer.localClientActive)
            {
                // there will be no spawn message, so start the client here too
                ClientScene.SetLocalObject(netId, gameObject);
                OnStartClient();
            }

            if (m_HasAuthority)
            {
                OnStartAuthority();
            }
        }

        internal void OnStartClient()
        {
            m_IsClient = true;
            CacheBehaviours();

            if (LogFilter.logDev) { Debug.Log("OnStartClient " + gameObject + " GUID:" + netId + " localPlayerAuthority:" + localPlayerAuthority); }
            for (int i = 0; i < m_NetworkBehaviours.Length; i++)
            {
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                try
                {
                    comp.PreStartClient(); // generated startup to resolve object references
                    comp.OnStartClient(); // user implemented startup
                }
                catch (Exception e)
                {
                    Debug.LogError("Exception in OnStartClient:" + e.Message + " " + e.StackTrace);
                }
            }
        }

        internal void OnStartAuthority()
        {
            if (m_NetworkBehaviours == null && LogFilter.logError)
            {
                Debug.LogError("Network object " + name + " not initialized properly. Do you have more than one NetworkIdentity in the same object? Did you forget to spawn this object with NetworkServer?", this);
                return;
            }

            for (int i = 0; i < m_NetworkBehaviours.Length; i++)
            {
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                try
                {
                    comp.OnStartAuthority();
                }
                catch (Exception e)
                {
                    Debug.LogError("Exception in OnStartAuthority:" + e.Message + " " + e.StackTrace);
                }
            }
        }

        internal void OnStopAuthority()
        {
            for (int i = 0; i < m_NetworkBehaviours.Length; i++)
            {
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                try
                {
                    comp.OnStopAuthority();
                }
                catch (Exception e)
                {
                    Debug.LogError("Exception in OnStopAuthority:" + e.Message + " " + e.StackTrace);
                }
            }
        }

        internal void OnSetLocalVisibility(bool vis)
        {
            for (int i = 0; i < m_NetworkBehaviours.Length; i++)
            {
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                try
                {
                    comp.OnSetLocalVisibility(vis);
                }
                catch (Exception e)
                {
                    Debug.LogError("Exception in OnSetLocalVisibility:" + e.Message + " " + e.StackTrace);
                }
            }
        }

        internal bool OnCheckObserver(NetworkConnection conn)
        {
            for (int i = 0; i < m_NetworkBehaviours.Length; i++)
            {
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                try
                {
                    if (!comp.OnCheckObserver(conn))
                        return false;
                }
                catch (Exception e)
                {
                    Debug.LogError("Exception in OnCheckObserver:" + e.Message + " " + e.StackTrace);
                }
            }
            return true;
        }

        ////////////////////////////////////////////////////////////////////////////////////////////////////////////////

        // vis2k: readstring bug prevention: https://issuetracker.unity3d.com/issues/unet-networkwriter-dot-write-causing-readstring-slash-readbytes-out-of-range-errors-in-clients
        // -> OnSerialize writes length,componentData,length,componentData,...
        // -> OnDeserialize carefully extracts each data, then deserializes each component with separate readers
        //    -> it will be impossible to read too many or too few bytes in OnDeserialize
        //    -> we can properly track down errors
        internal bool OnSerializeSafely(NetworkBehaviour comp, NetworkWriter writer, bool initialState)
        {
            // serialize into a temporary writer
            NetworkWriter temp = new NetworkWriter();
            bool result = false;
            try
            {
                result = comp.OnSerialize(temp, initialState);
            }
            catch (Exception e)
            {
                // show a detailed error and let the user know what went wrong
                Debug.LogError("OnSerialize failed for: object=" + name + " component=" + comp.GetType() + " sceneId=" + m_SceneId + "\n\n" + e.ToString());
            }
            byte[] bytes = temp.ToArray();
            if (LogFilter.logDebug) { Debug.Log("OnSerializeSafely written for object=" + comp.name + " component=" + comp.GetType() + " sceneId=" + m_SceneId + " length=" + bytes.Length); }

            // original HLAPI had a warning in UNetUpdate() in case of large state updates. let's move it here, might
            // be useful for debugging.
            if (bytes.Length > Transport.MaxPacketSize)
            {
                if (LogFilter.logWarn) { Debug.LogWarning("Large state update of " + bytes.Length + " bytes for netId:" + netId + " from script:" + comp); }
            }

            // serialize length,data into the real writer, untouched by user code
            writer.WriteBytesAndSize(bytes);
            return result;
        }

        // serialize all components (or only dirty ones if not initial state)
        // -> returns TRUE if any date other than dirtyMask was written!
        internal bool OnSerializeAllSafely(NetworkBehaviour[] components, NetworkWriter writer, bool initialState)
        {
            if (components.Length > 64)
            {
                if (LogFilter.logError) Debug.LogError("Only 64 NetworkBehaviour components are allowed for NetworkIdentity: " + name + " because of the dirtyComponentMask");
                return false;
            }

            // loop through all components only once and then write dirty+payload into the writer afterwards
            ulong dirtyComponentsMask = 0L;
            NetworkWriter payload = new NetworkWriter();
            for (int i = 0; i < components.Length; ++i)
            {
                // is this component dirty?
                // -> always serialize if initialState so all components are included in spawn packet
                // -> note: IsDirty() is false if the component isn't dirty or sendInterval isn't elapsed yet
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                if (initialState || comp.IsDirty())
                {
                    // set bit #i to 1 in dirty mask
                    dirtyComponentsMask |= (ulong)(1L << i);

                    // serialize the data
                    if (LogFilter.logDebug) { Debug.Log("OnSerializeAllSafely: " + name + " -> " + comp.GetType() + " initial=" + initialState); }
                    OnSerializeSafely(comp, payload, initialState);

                    // Clear dirty bits only if we are synchronizing data and not sending a spawn message.
                    // This preserves the behavior in HLAPI
                    if (!initialState)
                    {
                        comp.ClearAllDirtyBits();
                    }
                }
            }

            // did we write anything? then write dirty, payload and return true
            if (dirtyComponentsMask != 0L)
            {
                byte[] payloadBytes = payload.ToArray();
                writer.WritePackedUInt64(dirtyComponentsMask); // WritePacked64 so we don't write full 8 bytes if we don't have to
                writer.Write(payloadBytes, 0, payloadBytes.Length);
                return true;
            }

            // didn't write anything, return false
            return false;
        }

        // extra version that uses m_NetworkBehaviours so we can call it from the outside
        internal void OnSerializeAllSafely(NetworkWriter writer, bool initialState) { OnSerializeAllSafely(m_NetworkBehaviours, writer, initialState); }

        ////////////////////////////////////////////////////////////////////////////////////////////////////////////////

        internal void OnDeserializeSafely(NetworkBehaviour comp, NetworkReader reader, bool initialState)
        {
            // extract data length and data safely, untouched by user code
            // -> returns empty array if length is 0, so .Length is always the proper length
            byte[] bytes = reader.ReadBytesAndSize();
            if (LogFilter.logDebug) { Debug.Log("OnDeserializeSafely extracted: " + comp.name + " component=" + comp.GetType() + " sceneId=" + m_SceneId + " length=" + bytes.Length); }

            // call OnDeserialize with a temporary reader, so that the
            // original one can't be messed with. we also wrap it in a
            // try-catch block so there's no way to mess up another
            // component's deserialization
            try
            {
                comp.OnDeserialize(new NetworkReader(bytes), initialState);
            }
            catch (Exception e)
            {
                // show a detailed error and let the user know what went wrong
                Debug.LogError("OnDeserialize failed for: object=" + name + " component=" + comp.GetType() + " sceneId=" + m_SceneId + " length=" + bytes.Length + ". Possible Reasons:\n  * Do " + comp.GetType() + "'s OnSerialize and OnDeserialize calls write the same amount of data(" + bytes.Length +" bytes)? \n  * Was there an exception in " + comp.GetType() + "'s OnSerialize/OnDeserialize code?\n  * Are the server and client the exact same project?\n  * Maybe this OnDeserialize call was meant for another GameObject? The sceneIds can easily get out of sync if the Hierarchy was modified only in the client OR the server. Try rebuilding both.\n\n" + e.ToString());
            }
        }

        internal void OnDeserializeAllSafely(NetworkBehaviour[] components, NetworkReader reader, bool initialState)
        {
            // read component dirty mask
            ulong dirtyComponentsMask = reader.ReadPackedUInt64();

            // loop through all components and deserialize the dirty ones
            for (int i = 0; i < components.Length; ++i)
            {
                // is the dirty bit at position 'i' set to 1?
                ulong dirtyBit = (ulong)(1L << i);
                if ((dirtyComponentsMask & dirtyBit) != 0L)
                {
                    OnDeserializeSafely(components[i], reader, initialState);
                }
            }
        }

        // extra version that uses m_NetworkBehaviours so we can call it from the outside
        internal void OnDeserializeAllSafely(NetworkReader reader, bool initialState) { OnDeserializeAllSafely(m_NetworkBehaviours, reader, initialState); }

        ////////////////////////////////////////////////////////////////////////////////////////////////////////////////

        // happens on client
        internal void HandleClientAuthority(bool authority)
        {
            if (!localPlayerAuthority)
            {
                if (LogFilter.logError) { Debug.LogError("HandleClientAuthority " + gameObject + " does not have localPlayerAuthority"); }
                return;
            }

            ForceAuthority(authority);
        }

        // helper function for Handle** functions
        bool GetInvokeComponent(int cmdHash, Type invokeClass, out NetworkBehaviour invokeComponent)
        {
            // dont use GetComponent(), already have a list - avoids an allocation
            invokeComponent = Array.Find(m_NetworkBehaviours,
                comp => comp.GetType() == invokeClass || comp.GetType().IsSubclassOf(invokeClass)
            );
            if (invokeComponent == null)
            {
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logError) { Debug.LogError("Found no behaviour for incoming [" + errorCmdName + "] on " + gameObject + ",  the server and client should have the same NetworkBehaviour instances [netId=" + netId + "]."); }
                return false;
            }
            return true;
        }

        // happens on client
        internal void HandleSyncEvent(int cmdHash, NetworkReader reader)
        {
            // this doesn't use NetworkBehaviour.InvokeSyncEvent function (anymore). this method of calling is faster.
            // The hash is only looked up once, insted of twice(!) per NetworkBehaviour on the object.

            if (gameObject == null)
            {
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logWarn) { Debug.LogWarning("SyncEvent [" + errorCmdName + "] received for deleted object [netId=" + netId + "]"); }
                return;
            }

            // find the matching SyncEvent function and networkBehaviour class
            NetworkBehaviour.CmdDelegate invokeFunction;
            Type invokeClass;
            bool invokeFound = NetworkBehaviour.GetInvokerForHashSyncEvent(cmdHash, out invokeClass, out invokeFunction);
            if (!invokeFound)
            {
                // We don't get a valid lookup of the command name when it doesn't exist...
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logError) { Debug.LogError("Found no receiver for incoming [" + errorCmdName + "] on " + gameObject + ",  the server and client should have the same NetworkBehaviour instances [netId=" + netId + "]."); }
                return;
            }

            // find the right component to invoke the function on
            NetworkBehaviour invokeComponent;
            if (!GetInvokeComponent(cmdHash, invokeClass, out invokeComponent))
            {
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logWarn) { Debug.LogWarning("SyncEvent [" + errorCmdName + "] handler not found [netId=" + netId + "]"); }
                return;
            }

            invokeFunction(invokeComponent, reader);
        }

        // happens on client
        internal void HandleSyncList(int cmdHash, NetworkReader reader)
        {
            // this doesn't use NetworkBehaviour.InvokSyncList function (anymore). this method of calling is faster.
            // The hash is only looked up once, insted of twice(!) per NetworkBehaviour on the object.

            if (gameObject == null)
            {
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logWarn) { Debug.LogWarning("SyncList [" + errorCmdName + "] received for deleted object [netId=" + netId + "]"); }
                return;
            }

            // find the matching SyncList function and networkBehaviour class
            NetworkBehaviour.CmdDelegate invokeFunction;
            Type invokeClass;
            bool invokeFound = NetworkBehaviour.GetInvokerForHashSyncList(cmdHash, out invokeClass, out invokeFunction);
            if (!invokeFound)
            {
                // We don't get a valid lookup of the command name when it doesn't exist...
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logError) { Debug.LogError("Found no receiver for incoming [" + errorCmdName + "] on " + gameObject + ",  the server and client should have the same NetworkBehaviour instances [netId=" + netId + "]."); }
                return;
            }

            // find the right component to invoke the function on
            NetworkBehaviour invokeComponent;
            if (!GetInvokeComponent(cmdHash, invokeClass, out invokeComponent))
            {
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logWarn) { Debug.LogWarning("SyncList [" + errorCmdName + "] handler not found [netId=" + netId + "]"); }
                return;
            }

            invokeFunction(invokeComponent, reader);
        }

        // happens on server
        internal void HandleCommand(int cmdHash, NetworkReader reader)
        {
            // this doesn't use NetworkBehaviour.InvokeCommand function (anymore). this method of calling is faster.
            // The hash is only looked up once, insted of twice(!) per NetworkBehaviour on the object.

            if (gameObject == null)
            {
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logWarn) { Debug.LogWarning("Command [" + errorCmdName + "] received for deleted object [netId=" + netId + "]"); }
                return;
            }

            // find the matching Command function and networkBehaviour class
            NetworkBehaviour.CmdDelegate invokeFunction;
            Type invokeClass;
            bool invokeFound = NetworkBehaviour.GetInvokerForHashCommand(cmdHash, out invokeClass, out invokeFunction);
            if (!invokeFound)
            {
                // We don't get a valid lookup of the command name when it doesn't exist...
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logError) { Debug.LogError("Found no receiver for incoming [" + errorCmdName + "] on " + gameObject + ",  the server and client should have the same NetworkBehaviour instances [netId=" + netId + "]."); }
                return;
            }

            // find the right component to invoke the function on
            NetworkBehaviour invokeComponent;
            if (!GetInvokeComponent(cmdHash, invokeClass, out invokeComponent))
            {
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logWarn) { Debug.LogWarning("Command [" + errorCmdName + "] handler not found [netId=" + netId + "]"); }
                return;
            }

            invokeFunction(invokeComponent, reader);
        }

        // happens on client
        internal void HandleRPC(int cmdHash, NetworkReader reader)
        {
            // this doesn't use NetworkBehaviour.InvokeClientRpc function (anymore). this method of calling is faster.
            // The hash is only looked up once, insted of twice(!) per NetworkBehaviour on the object.

            if (gameObject == null)
            {
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logWarn) { Debug.LogWarning("ClientRpc [" + errorCmdName + "] received for deleted object [netId=" + netId + "]"); }
                return;
            }

            // find the matching ClientRpc function and networkBehaviour class
            NetworkBehaviour.CmdDelegate invokeFunction;
            Type invokeClass;
            bool invokeFound = NetworkBehaviour.GetInvokerForHashClientRpc(cmdHash, out invokeClass, out invokeFunction);
            if (!invokeFound)
            {
                // We don't get a valid lookup of the command name when it doesn't exist...
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logError) { Debug.LogError("Found no receiver for incoming [" + errorCmdName + "] on " + gameObject + ",  the server and client should have the same NetworkBehaviour instances [netId=" + netId + "]."); }
                return;
            }

            // find the right component to invoke the function on
            NetworkBehaviour invokeComponent;
            if (!GetInvokeComponent(cmdHash, invokeClass, out invokeComponent))
            {
                string errorCmdName = NetworkBehaviour.GetCmdHashHandlerName(cmdHash);
                if (LogFilter.logWarn) { Debug.LogWarning("ClientRpc [" + errorCmdName + "] handler not found [netId=" + netId + "]"); }
                return;
            }

            invokeFunction(invokeComponent, reader);
        }

        // invoked by unity runtime immediately after the regular "Update()" function.
        internal void UNetUpdate()
        {
            // serialize all the dirty components and send (if any were dirty)
            NetworkWriter writer = new NetworkWriter();
            if (OnSerializeAllSafely(m_NetworkBehaviours, writer, false))
            {
                // construct message and send
                UpdateVarsMessage message = new UpdateVarsMessage();
                message.netId = netId;
                message.payload = writer.ToArray();

                NetworkServer.SendToReady(gameObject, (short)MsgType.UpdateVars, message);
            }
        }

        internal void OnUpdateVars(NetworkReader reader, bool initialState)
        {
            if (initialState && m_NetworkBehaviours == null)
            {
                m_NetworkBehaviours = GetComponents<NetworkBehaviour>();
            }

            OnDeserializeAllSafely(m_NetworkBehaviours, reader, initialState);
        }

        internal void SetLocalPlayer()
        {
            m_IsLocalPlayer = true;

            // there is an ordering issue here that originAuthority solves. OnStartAuthority should only be called if m_HasAuthority was false when this function began,
            // or it will be called twice for this object. But that state is lost by the time OnStartAuthority is called below, so the original value is cached
            // here to be checked below.
            bool originAuthority = m_HasAuthority;
            if (localPlayerAuthority)
            {
                m_HasAuthority = true;
            }

            for (int i = 0; i < m_NetworkBehaviours.Length; i++)
            {
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                comp.OnStartLocalPlayer();

                if (localPlayerAuthority && !originAuthority)
                {
                    comp.OnStartAuthority();
                }
            }
        }

        internal void SetConnectionToServer(NetworkConnection conn)
        {
            m_ConnectionToServer = conn;
        }

        internal void SetConnectionToClient(NetworkConnection conn)
        {
            m_ConnectionToClient = conn;
        }

        internal void OnNetworkDestroy()
        {
            for (int i = 0; m_NetworkBehaviours != null && i < m_NetworkBehaviours.Length; i++)
            {
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                comp.OnNetworkDestroy();
            }
            m_IsServer = false;
        }

        internal void ClearObservers()
        {
            if (m_Observers != null)
            {
                int count = m_Observers.Count;
                for (int i = 0; i < count; i++)
                {
                    m_Observers[i].RemoveFromVisList(this, true);
                }
                m_Observers.Clear();
                m_ObserverConnections.Clear();
            }
        }

        internal void AddObserver(NetworkConnection conn)
        {
            if (m_Observers == null)
            {
                if (LogFilter.logError) { Debug.LogError("AddObserver for " + gameObject + " observer list is null"); }
                return;
            }

            // uses hashset for better-than-list-iteration lookup performance.
            if (m_ObserverConnections.Contains(conn.connectionId))
            {
                // if we try to add a connectionId that was already added, then
                // we may have generated one that was already in use.
                return;
            }

            if (LogFilter.logDev) { Debug.Log("Added observer " + conn.address + " added for " + gameObject); }

            m_Observers.Add(conn);
            m_ObserverConnections.Add(conn.connectionId);
            conn.AddToVisList(this);
        }

        internal void RemoveObserver(NetworkConnection conn)
        {
            if (m_Observers == null)
                return;

            // NOTE this is linear performance now..
            m_Observers.Remove(conn);
            m_ObserverConnections.Remove(conn.connectionId);
            conn.RemoveFromVisList(this, false);
        }

        public void RebuildObservers(bool initialize)
        {
            if (m_Observers == null)
                return;

            bool changed = false;
            bool result = false;
            HashSet<NetworkConnection> newObservers = new HashSet<NetworkConnection>();
            HashSet<NetworkConnection> oldObservers = new HashSet<NetworkConnection>(m_Observers);

            for (int i = 0; i < m_NetworkBehaviours.Length; i++)
            {
                NetworkBehaviour comp = m_NetworkBehaviours[i];
                result |= comp.OnRebuildObservers(newObservers, initialize);
            }
            if (!result)
            {
                // none of the behaviours rebuilt our observers, use built-in rebuild method
                if (initialize)
                {
                    for (int i = 0; i < NetworkServer.connections.Count; i++)
                    {
                        var conn = NetworkServer.connections[i];
                        if (conn != null && conn.isReady)
                            AddObserver(conn);
                    }

                    if (NetworkServer.localConnection != null && NetworkServer.localConnection.isReady)
                    {
                        AddObserver(NetworkServer.localConnection);
                    }
                }
                return;
            }

            // apply changes from rebuild
            foreach (var conn in newObservers)
            {
                if (conn == null)
                {
                    continue;
                }

                if (!conn.isReady)
                {
                    if (LogFilter.logWarn) { Debug.LogWarning("Observer is not ready for " + gameObject + " " + conn); }
                    continue;
                }

                if (initialize || !oldObservers.Contains(conn))
                {
                    // new observer
                    conn.AddToVisList(this);
                    if (LogFilter.logDebug) { Debug.Log("New Observer for " + gameObject + " " + conn); }
                    changed = true;
                }
            }

            foreach (var conn in oldObservers)
            {
                if (!newObservers.Contains(conn))
                {
                    // removed observer
                    conn.RemoveFromVisList(this, false);
                    if (LogFilter.logDebug) { Debug.Log("Removed Observer for " + gameObject + " " + conn); }
                    changed = true;
                }
            }

            // special case for local client.
            if (initialize)
            {
                if (!newObservers.Contains(NetworkServer.localConnection))
                {
                    OnSetLocalVisibility(false);
                }
            }

            if (changed)
            {
                m_Observers = new List<NetworkConnection>(newObservers);

                // rebuild hashset once we have the final set of new observers
                m_ObserverConnections.Clear();
                for (int i = 0; i < m_Observers.Count; i++)
                {
                    m_ObserverConnections.Add(m_Observers[i].connectionId);
                }
            }
        }

        public bool RemoveClientAuthority(NetworkConnection conn)
        {
            if (!isServer)
            {
                if (LogFilter.logError) { Debug.LogError("RemoveClientAuthority can only be call on the server for spawned objects."); }
                return false;
            }

            if (connectionToClient != null)
            {
                if (LogFilter.logError) { Debug.LogError("RemoveClientAuthority cannot remove authority for a player object"); }
                return false;
            }

            if (m_ClientAuthorityOwner == null)
            {
                if (LogFilter.logError) { Debug.LogError("RemoveClientAuthority for " + gameObject + " has no clientAuthority owner."); }
                return false;
            }

            if (m_ClientAuthorityOwner != conn)
            {
                if (LogFilter.logError) { Debug.LogError("RemoveClientAuthority for " + gameObject + " has different owner."); }
                return false;
            }

            m_ClientAuthorityOwner.RemoveOwnedObject(this);
            m_ClientAuthorityOwner = null;

            // server now has authority (this is only called on server)
            ForceAuthority(true);

            // send msg to that client
            var msg = new ClientAuthorityMessage();
            msg.netId = netId;
            msg.authority = false;
            conn.Send((short)MsgType.LocalClientAuthority, msg);

            if (clientAuthorityCallback != null)
            {
                clientAuthorityCallback(conn, this, false);
            }
            return true;
        }

        public bool AssignClientAuthority(NetworkConnection conn)
        {
            if (!isServer)
            {
                if (LogFilter.logError) { Debug.LogError("AssignClientAuthority can only be call on the server for spawned objects."); }
                return false;
            }
            if (!localPlayerAuthority)
            {
                if (LogFilter.logError) { Debug.LogError("AssignClientAuthority can only be used for NetworkIdentity component with LocalPlayerAuthority set."); }
                return false;
            }

            if (m_ClientAuthorityOwner != null && conn != m_ClientAuthorityOwner)
            {
                if (LogFilter.logError) { Debug.LogError("AssignClientAuthority for " + gameObject + " already has an owner. Use RemoveClientAuthority() first."); }
                return false;
            }

            if (conn == null)
            {
                if (LogFilter.logError) { Debug.LogError("AssignClientAuthority for " + gameObject + " owner cannot be null. Use RemoveClientAuthority() instead."); }
                return false;
            }

            m_ClientAuthorityOwner = conn;
            m_ClientAuthorityOwner.AddOwnedObject(this);

            // server no longer has authority (this is called on server). Note that local client could re-acquire authority below
            ForceAuthority(false);

            // send msg to that client
            var msg = new ClientAuthorityMessage();
            msg.netId = netId;
            msg.authority = true;
            conn.Send((short)MsgType.LocalClientAuthority, msg);

            if (clientAuthorityCallback != null)
            {
                clientAuthorityCallback(conn, this, true);
            }
            return true;
        }

        // marks the identity for future reset, this is because we cant reset the identity during destroy
        // as people might want to be able to read the members inside OnDestroy(), and we have no way
        // of invoking reset after OnDestroy is called.
        internal void MarkForReset()
        {
            m_Reset = true;
        }

        // if we have marked an identity for reset we do the actual reset.
        internal void Reset()
        {
            if (!m_Reset)
                return;

            m_Reset = false;
            m_IsServer = false;
            m_IsClient = false;
            m_HasAuthority = false;

            m_NetId = NetworkInstanceId.Zero;
            m_IsLocalPlayer = false;
            m_ConnectionToServer = null;
            m_ConnectionToClient = null;
            m_NetworkBehaviours = null;

            ClearObservers();
            m_ClientAuthorityOwner = null;
        }

#if UNITY_EDITOR
        // this is invoked by the UnityEngine when a Mono Domain reload happens in the editor.
        // the transport layer has state in C++, so when the C# state is lost (on domain reload), the C++ transport layer must be shutown as well.
        static internal void UNetDomainReload()
        {
            NetworkManager.OnDomainReload();
        }
#endif

        // this is invoked by the UnityEngine
        public static void UNetStaticUpdate()
        {
            NetworkServer.Update();
            NetworkClient.UpdateClients();
            NetworkManager.UpdateScene();
        }
    };
}