(svn r14709) -Codechange: make a clearer distinction between 'unique' client identification ids and the indices into the clients/client info arrays.

11 files changed, 161 insertions, 157 deletions

diff --git a/src/network/core/tcp.cpp b/src/network/core/tcp.cpp
index 6450d4778..f6cef8728 100644
--- a/src/network/core/tcp.cpp
+++ b/src/network/core/tcp.cpp
@@ -22,7 +22,7 @@ void NetworkTCPSocketHandler::Initialize()
 {
 	this->sock              = INVALID_SOCKET;
 
-	this->index             = 0;
+	this->client_id         = INVALID_CLIENT_ID;
 	this->last_frame        = 0;
 	this->last_frame_server = 0;
 	this->lag_test          = 0;
diff --git a/src/network/core/tcp.h b/src/network/core/tcp.h
index 6af0d17f8..1bafbf26e 100644
--- a/src/network/core/tcp.h
+++ b/src/network/core/tcp.h
@@ -91,7 +91,7 @@ private:
 	Packet *packet_queue;     ///< Packets that are awaiting delivery
 	Packet *packet_recv;      ///< Partially received packet
 public:
-	uint16 index;             ///< Client index
+	ClientID client_id;       ///< Client identifier
 	uint32 last_frame;        ///< Last frame we have executed
 	uint32 last_frame_server; ///< Last frame the server has executed
 	byte lag_test;            ///< Byte used for lag-testing the client
diff --git a/src/network/network.cpp b/src/network/network.cpp
index 05839042d..44fd28b0b 100644
--- a/src/network/network.cpp
+++ b/src/network/network.cpp
@@ -43,6 +43,8 @@
 #include "table/strings.h"
 #include "../company_base.h"
 
+DECLARE_POSTFIX_INCREMENT(ClientID);
+
 bool _network_server;     ///< network-server is active
 bool _network_available;  ///< is network mode available?
 bool _network_dedicated;  ///< are we a dedicated server?
@@ -50,8 +52,8 @@ bool _is_network_server;  ///< Does this client wants to be a network-server?
 NetworkServerGameInfo _network_game_info;
 NetworkCompanyInfo _network_company_info[MAX_COMPANIES];
 NetworkClientInfo _network_client_info[MAX_CLIENT_INFO];
-uint16 _network_own_client_index;
-uint16 _redirect_console_to_client;
+ClientID _network_own_client_id;
+ClientID _redirect_console_to_client;
 bool _network_need_advertise;
 uint32 _network_last_advertise_frame;
 uint8 _network_reconnect;
@@ -92,19 +94,19 @@ static SOCKET _listensocket;
 
 // The amount of clients connected
 static byte _network_clients_connected = 0;
-// The index counter for new clients (is never decreased)
-static uint16 _network_client_index = NETWORK_SERVER_INDEX + 1;
+// The identifier counter for new clients (is never decreased)
+static ClientID _network_client_id = CLIENT_ID_FIRST;
 
 /* Some externs / forwards */
 extern void StateGameLoop();
 
-// Function that looks up the CI for a given client-index
-NetworkClientInfo *NetworkFindClientInfoFromIndex(uint16 client_index)
+// Function that looks up the CI for a given client-identifier
+NetworkClientInfo *NetworkFindClientInfoFromIndex(ClientID client_id)
 {
 	NetworkClientInfo *ci;
 
 	for (ci = _network_client_info; ci != endof(_network_client_info); ci++) {
-		if (ci->client_index == client_index) return ci;
+		if (ci->client_id == client_id) return ci;
 	}
 
 	return NULL;
@@ -125,13 +127,13 @@ NetworkClientInfo *NetworkFindClientInfoFromIP(const char *ip)
 	return NULL;
 }
 
-// Function that looks up the CS for a given client-index
-NetworkTCPSocketHandler *NetworkFindClientStateFromIndex(uint16 client_index)
+// Function that looks up the CS for a given client-identifier
+NetworkTCPSocketHandler *NetworkFindClientStateFromClientID(ClientID client_id)
 {
 	NetworkTCPSocketHandler *cs;
 
 	for (cs = _clients; cs != endof(_clients); cs++) {
-		if (cs->index == client_index) return cs;
+		if (cs->client_id == client_id) return cs;
 	}
 
 	return NULL;
@@ -144,7 +146,7 @@ void NetworkGetClientName(char *client_name, size_t size, const NetworkTCPSocket
 	const NetworkClientInfo *ci = DEREF_CLIENT_INFO(cs);
 
 	if (ci->client_name[0] == '\0') {
-		snprintf(client_name, size, "Client #%4d", cs->index);
+		snprintf(client_name, size, "Client #%4d", cs->client_id);
 	} else {
 		ttd_strlcpy(client_name, ci->client_name, size);
 	}
@@ -361,13 +363,13 @@ void CheckMinActiveClients()
 
 		_min_active_clients_paused = true;
 		DoCommandP(0, 1, 0, NULL, CMD_PAUSE);
-		NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game paused (not enough players)", NETWORK_SERVER_INDEX);
+		NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game paused (not enough players)", CLIENT_ID_SERVER);
 	} else {
 		if (!_min_active_clients_paused) return;
 
 		_min_active_clients_paused = false;
 		DoCommandP(0, 0, 0, NULL, CMD_PAUSE);
-		NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game unpaused (enough players)", NETWORK_SERVER_INDEX);
+		NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game unpaused (enough players)", CLIENT_ID_SERVER);
 	}
 }
 
@@ -420,8 +422,8 @@ static NetworkTCPSocketHandler *NetworkAllocClient(SOCKET s)
 		NetworkClientInfo *ci = DEREF_CLIENT_INFO(cs);
 		memset(ci, 0, sizeof(*ci));
 
-		cs->index = _network_client_index++;
-		ci->client_index = cs->index;
+		cs->client_id = _network_client_id++;
+		ci->client_id = cs->client_id;
 		ci->client_playas = COMPANY_INACTIVE_CLIENT;
 		ci->join_date = _date;
 
@@ -441,7 +443,7 @@ void NetworkCloseClient(NetworkTCPSocketHandler *cs)
 		return;
 	}
 
-	DEBUG(net, 1, "Closed client connection %d", cs->index);
+	DEBUG(net, 1, "Closed client connection %d", cs->client_id);
 
 	if (!cs->has_quit && _network_server && cs->status > STATUS_INACTIVE) {
 		// We did not receive a leave message from this client...
@@ -459,7 +461,7 @@ void NetworkCloseClient(NetworkTCPSocketHandler *cs)
 		// Inform other clients of this... strange leaving ;)
 		FOR_ALL_CLIENTS(new_cs) {
 			if (new_cs->status > STATUS_AUTH && cs != new_cs) {
-				SEND_COMMAND(PACKET_SERVER_ERROR_QUIT)(new_cs, cs->index, errorno);
+				SEND_COMMAND(PACKET_SERVER_ERROR_QUIT)(new_cs, cs->client_id, errorno);
 			}
 		}
 	}
@@ -467,7 +469,7 @@ void NetworkCloseClient(NetworkTCPSocketHandler *cs)
 	/* When the client was PRE_ACTIVE, the server was in pause mode, so unpause */
 	if (cs->status == STATUS_PRE_ACTIVE && _settings_client.network.pause_on_join) {
 		DoCommandP(0, 0, 0, NULL, CMD_PAUSE);
-		NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game unpaused", NETWORK_SERVER_INDEX);
+		NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game unpaused", CLIENT_ID_SERVER);
 	}
 
 	cs->Destroy();
@@ -493,8 +495,8 @@ void NetworkCloseClient(NetworkTCPSocketHandler *cs)
 	// Reset the status of the last socket
 	cs->sock = INVALID_SOCKET;
 	cs->status = STATUS_INACTIVE;
-	cs->index = NETWORK_EMPTY_INDEX;
-	ci->client_index = NETWORK_EMPTY_INDEX;
+	cs->client_id = INVALID_CLIENT_ID;
+	ci->client_id = INVALID_CLIENT_ID;
 
 	CheckMinActiveClients();
 }
@@ -808,11 +810,11 @@ static void NetworkInitGameInfo()
 	_network_game_info.start_date = ConvertYMDToDate(_settings_game.game_creation.starting_year, 0, 1);
 
 	// We use _network_client_info[MAX_CLIENT_INFO - 1] to store the server-data in it
-	//  The index is NETWORK_SERVER_INDEX ( = 1)
+	//  The client identifier is CLIENT_ID_SERVER ( = 1)
 	ci = &_network_client_info[MAX_CLIENT_INFO - 1];
 	memset(ci, 0, sizeof(*ci));
 
-	ci->client_index = NETWORK_SERVER_INDEX;
+	ci->client_id = CLIENT_ID_SERVER;
 	ci->client_playas = _network_dedicated ? COMPANY_SPECTATOR : _local_company;
 
 	strecpy(ci->client_name, _settings_client.network.client_name, lastof(ci->client_name));
@@ -840,7 +842,7 @@ bool NetworkServerStart()
 	_frame_counter_server = 0;
 	_frame_counter_max = 0;
 	_last_sync_frame = 0;
-	_network_own_client_index = NETWORK_SERVER_INDEX;
+	_network_own_client_id = CLIENT_ID_SERVER;
 
 	/* Non-dedicated server will always be company #1 */
 	if (!_network_dedicated) _network_playas = COMPANY_FIRST;
diff --git a/src/network/network_chat_gui.cpp b/src/network/network_chat_gui.cpp
index 02aec095a..108209cf3 100644
--- a/src/network/network_chat_gui.cpp
+++ b/src/network/network_chat_gui.cpp
@@ -259,7 +259,7 @@ static void SendChat(const char *buf, DestType type, int dest)
 	if (!_network_server) {
 		SEND_COMMAND(PACKET_CLIENT_CHAT)((NetworkAction)(NETWORK_ACTION_CHAT + type), type, dest, buf);
 	} else {
-		NetworkServerSendChat((NetworkAction)(NETWORK_ACTION_CHAT + type), type, dest, buf, NETWORK_SERVER_INDEX);
+		NetworkServerSendChat((NetworkAction)(NETWORK_ACTION_CHAT + type), type, dest, buf, CLIENT_ID_SERVER);
 	}
 }
 
@@ -301,7 +301,7 @@ struct NetworkChatWindow : public QueryStringBaseWindow {
 		/* First, try clients */
 		if (*item < MAX_CLIENT_INFO) {
 			/* Skip inactive clients */
-			while (_network_client_info[*item].client_index == NETWORK_EMPTY_INDEX && *item < MAX_CLIENT_INFO) (*item)++;
+			while (_network_client_info[*item].client_id == INVALID_CLIENT_ID && *item < MAX_CLIENT_INFO) (*item)++;
 			if (*item < MAX_CLIENT_INFO) return _network_client_info[*item].client_name;
 		}
 
diff --git a/src/network/network_client.cpp b/src/network/network_client.cpp
index c90ffcc73..3c6f4dff1 100644
--- a/src/network/network_client.cpp
+++ b/src/network/network_client.cpp
@@ -244,7 +244,7 @@ DEF_CLIENT_SEND_COMMAND_PARAM(PACKET_CLIENT_CHAT)(NetworkAction action, DestType
 	// Data:
 	//    uint8:  ActionID (see network_data.h, NetworkAction)
 	//    uint8:  Destination Type (see network_data.h, DestType);
-	//    uint16: Destination Company/Client
+	//    uint32: Destination CompanyID/Client-identifier
 	//    String: Message (max NETWORK_CHAT_LENGTH)
 	//
 
@@ -252,7 +252,7 @@ DEF_CLIENT_SEND_COMMAND_PARAM(PACKET_CLIENT_CHAT)(NetworkAction action, DestType
 
 	p->Send_uint8 (action);
 	p->Send_uint8 (type);
-	p->Send_uint16(dest);
+	p->Send_uint32(dest);
 	p->Send_string(msg);
 	MY_CLIENT->Send_Packet(p);
 }
@@ -392,12 +392,12 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_COMPANY_INFO)
 }
 
 // This packet contains info about the client (playas and name)
-//  as client we save this in NetworkClientInfo, linked via 'index'
+//  as client we save this in NetworkClientInfo, linked via 'client_id'
 //  which is always an unique number on a server.
 DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_CLIENT_INFO)
 {
 	NetworkClientInfo *ci;
-	uint16 index = p->Recv_uint16();
+	ClientID client_id = (ClientID)p->Recv_uint32();
 	CompanyID playas = (CompanyID)p->Recv_uint8();
 	char name[NETWORK_NAME_LENGTH];
 
@@ -406,9 +406,9 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_CLIENT_INFO)
 	if (MY_CLIENT->has_quit) return NETWORK_RECV_STATUS_CONN_LOST;
 
 	/* Do we receive a change of data? Most likely we changed playas */
-	if (index == _network_own_client_index) _network_playas = playas;
+	if (client_id == _network_own_client_id) _network_playas = playas;
 
-	ci = NetworkFindClientInfoFromIndex(index);
+	ci = NetworkFindClientInfoFromIndex(client_id);
 	if (ci != NULL) {
 		if (playas == ci->client_playas && strcmp(name, ci->client_name) != 0) {
 			// Client name changed, display the change
@@ -426,10 +426,10 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_CLIENT_INFO)
 		return NETWORK_RECV_STATUS_OKAY;
 	}
 
-	// We don't have this index yet, find an empty index, and put the data there
-	ci = NetworkFindClientInfoFromIndex(NETWORK_EMPTY_INDEX);
+	// We don't have this client_id yet, find an empty client_id, and put the data there
+	ci = NetworkFindClientInfoFromIndex(INVALID_CLIENT_ID);
 	if (ci != NULL) {
-		ci->client_index = index;
+		ci->client_id = client_id;
 		ci->client_playas = playas;
 
 		strecpy(ci->client_name, name, lastof(ci->client_name));
@@ -530,7 +530,7 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_NEED_PASSWORD)
 
 DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_WELCOME)
 {
-	_network_own_client_index = p->Recv_uint16();
+	_network_own_client_id = (ClientID)p->Recv_uint32();
 
 	/* Initialize the password hash salting variables, even if they were previously. */
 	_password_game_seed = p->Recv_uint32();
@@ -717,11 +717,11 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_CHAT)
 	const NetworkClientInfo *ci = NULL, *ci_to;
 
 	NetworkAction action = (NetworkAction)p->Recv_uint8();
-	uint16 index = p->Recv_uint16();
+	ClientID client_id = (ClientID)p->Recv_uint32();
 	bool self_send = p->Recv_bool();
 	p->Recv_string(msg, NETWORK_CHAT_LENGTH);
 
-	ci_to = NetworkFindClientInfoFromIndex(index);
+	ci_to = NetworkFindClientInfoFromIndex(client_id);
 	if (ci_to == NULL) return NETWORK_RECV_STATUS_OKAY;
 
 	/* Did we initiate the action locally? */
@@ -730,7 +730,7 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_CHAT)
 			case NETWORK_ACTION_CHAT_CLIENT:
 				/* For speaking to client we need the client-name */
 				snprintf(name, sizeof(name), "%s", ci_to->client_name);
-				ci = NetworkFindClientInfoFromIndex(_network_own_client_index);
+				ci = NetworkFindClientInfoFromIndex(_network_own_client_id);
 				break;
 
 			/* For speaking to company or giving money, we need the company-name */
@@ -742,7 +742,7 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_CHAT)
 				SetDParam(0, ci_to->client_playas);
 
 				GetString(name, str, lastof(name));
-				ci = NetworkFindClientInfoFromIndex(_network_own_client_index);
+				ci = NetworkFindClientInfoFromIndex(_network_own_client_id);
 			} break;
 
 			default: NOT_REACHED(); break;
@@ -761,18 +761,17 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_CHAT)
 DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_ERROR_QUIT)
 {
 	char str[100];
-	uint16 index;
 	NetworkClientInfo *ci;
 
-	index = p->Recv_uint16();
+	ClientID client_id = (ClientID)p->Recv_uint32();
 	GetNetworkErrorMsg(str, (NetworkErrorCode)p->Recv_uint8(), lastof(str));
 
-	ci = NetworkFindClientInfoFromIndex(index);
+	ci = NetworkFindClientInfoFromIndex(client_id);
 	if (ci != NULL) {
 		NetworkTextMessage(NETWORK_ACTION_LEAVE, CC_DEFAULT, false, ci->client_name, "%s", str);
 
 		// The client is gone, give the NetworkClientInfo free
-		ci->client_index = NETWORK_EMPTY_INDEX;
+		ci->client_id = INVALID_CLIENT_ID;
 	}
 
 	InvalidateWindow(WC_CLIENT_LIST, 0);
@@ -783,20 +782,19 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_ERROR_QUIT)
 DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_QUIT)
 {
 	char str[100];
-	uint16 index;
 	NetworkClientInfo *ci;
 
-	index = p->Recv_uint16();
+	ClientID client_id = (ClientID)p->Recv_uint32();
 	p->Recv_string(str, lengthof(str));
 
-	ci = NetworkFindClientInfoFromIndex(index);
+	ci = NetworkFindClientInfoFromIndex(client_id);
 	if (ci != NULL) {
 		NetworkTextMessage(NETWORK_ACTION_LEAVE, CC_DEFAULT, false, ci->client_name, "%s", str);
 
 		// The client is gone, give the NetworkClientInfo free
-		ci->client_index = NETWORK_EMPTY_INDEX;
+		ci->client_id = INVALID_CLIENT_ID;
 	} else {
-		DEBUG(net, 0, "Unknown client (%d) is leaving the game", index);
+		DEBUG(net, 0, "Unknown client (%d) is leaving the game", client_id);
 	}
 
 	InvalidateWindow(WC_CLIENT_LIST, 0);
@@ -807,12 +805,9 @@ DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_QUIT)
 
 DEF_CLIENT_RECEIVE_COMMAND(PACKET_SERVER_JOIN)
 {
-	uint16 index;
-	NetworkClientInfo *ci;
-
-	index = p->Recv_uint16();
+	ClientID client_id = (ClientID)p->Recv_uint32();
 
-	ci = NetworkFindClientInfoFromIndex(index);
+	NetworkClientInfo *ci = NetworkFindClientInfoFromIndex(client_id);
 	if (ci != NULL)
 		NetworkTextMessage(NETWORK_ACTION_JOIN, CC_DEFAULT, false, ci->client_name, "");
 
@@ -940,7 +935,7 @@ void NetworkClientSendRcon(const char *password, const char *command)
 
 void NetworkUpdateClientName()
 {
-	NetworkClientInfo *ci = NetworkFindClientInfoFromIndex(_network_own_client_index);
+	NetworkClientInfo *ci = NetworkFindClientInfoFromIndex(_network_own_client_id);
 
 	if (ci == NULL) return;
 
@@ -952,7 +947,7 @@ void NetworkUpdateClientName()
 			if (NetworkFindName(_settings_client.network.client_name)) {
 				NetworkTextMessage(NETWORK_ACTION_NAME_CHANGE, CC_DEFAULT, false, ci->client_name, "%s", _settings_client.network.client_name);
 				strecpy(ci->client_name, _settings_client.network.client_name, lastof(ci->client_name));
-				NetworkUpdateClientInfo(NETWORK_SERVER_INDEX);
+				NetworkUpdateClientInfo(CLIENT_ID_SERVER);
 			}
 		}
 	}
diff --git a/src/network/network_func.h b/src/network/network_func.h
index 13e45232d..cacf643f6 100644
--- a/src/network/network_func.h
+++ b/src/network/network_func.h
@@ -14,8 +14,8 @@ extern NetworkServerGameInfo _network_game_info;
 extern NetworkCompanyInfo _network_company_info[MAX_COMPANIES];
 extern NetworkClientInfo _network_client_info[MAX_CLIENT_INFO];
 
-extern uint16 _network_own_client_index;
-extern uint16 _redirect_console_to_client;
+extern ClientID _network_own_client_id;
+extern ClientID _redirect_console_to_client;
 extern bool _network_need_advertise;
 extern uint32 _network_last_advertise_frame;
 extern uint8 _network_reconnect;
@@ -36,7 +36,7 @@ void ParseConnectionString(const char **company, const char **port, char *connec
 void NetworkStartDebugLog(const char *hostname, uint16 port);
 void NetworkPopulateCompanyInfo();
 
-void NetworkUpdateClientInfo(uint16 client_index);
+void NetworkUpdateClientInfo(ClientID client_id);
 bool NetworkClientConnectGame(const char *host, uint16 port);
 void NetworkClientSendRcon(const char *password, const char *command);
 void NetworkClientSendChat(NetworkAction action, DestType type, int dest, const char *msg);
@@ -49,20 +49,20 @@ void NetworkServerChangeOwner(Owner current_owner, Owner new_owner);
 void NetworkServerShowStatusToConsole();
 bool NetworkServerStart();
 
-NetworkClientInfo *NetworkFindClientInfoFromIndex(uint16 client_index);
+NetworkClientInfo *NetworkFindClientInfoFromIndex(ClientID client_id);
 NetworkClientInfo *NetworkFindClientInfoFromIP(const char *ip);
 const char* GetClientIP(const NetworkClientInfo *ci);
 
-void NetworkServerSendRcon(uint16 client_index, ConsoleColour colour_code, const char *string);
-void NetworkServerSendError(uint16 client_index, NetworkErrorCode error);
-void NetworkServerSendChat(NetworkAction action, DestType type, int dest, const char *msg, uint16 from_index);
+void NetworkServerSendRcon(ClientID client_id, ConsoleColour colour_code, const char *string);
+void NetworkServerSendError(ClientID client_id, NetworkErrorCode error);
+void NetworkServerSendChat(NetworkAction action, DestType type, int dest, const char *msg, ClientID from_id);
 
 void NetworkInitChatMessage();
 void CDECL NetworkAddChatMessage(uint16 color, uint8 duration, const char *message, ...);
 void NetworkUndrawChatMessage();
 void NetworkChatMessageDailyLoop();
 
-#define FOR_ALL_ACTIVE_CLIENT_INFOS(ci) for (ci = _network_client_info; ci != endof(_network_client_info); ci++) if (ci->client_index != NETWORK_EMPTY_INDEX)
+#define FOR_ALL_ACTIVE_CLIENT_INFOS(ci) for (ci = _network_client_info; ci != endof(_network_client_info); ci++) if (ci->client_id != INVALID_CLIENT_ID)
 
 #endif /* ENABLE_NETWORK */
 #endif /* NETWORK_FUNC_H */
diff --git a/src/network/network_gui.cpp b/src/network/network_gui.cpp
index b0bf24f25..df404966e 100644
--- a/src/network/network_gui.cpp
+++ b/src/network/network_gui.cpp
@@ -1447,7 +1447,7 @@ static void ClientList_GiveMoney(byte client_no)
 static void ClientList_SpeakToClient(byte client_no)
 {
 	if (NetworkFindClientInfo(client_no) != NULL) {
-		ShowNetworkChatQueryWindow(DESTTYPE_CLIENT, NetworkFindClientInfo(client_no)->client_index);
+		ShowNetworkChatQueryWindow(DESTTYPE_CLIENT, NetworkFindClientInfo(client_no)->client_id);
 	}
 }
 
@@ -1488,7 +1488,7 @@ struct NetworkClientListPopupWindow : Window {
 		const NetworkClientInfo *ci = NetworkFindClientInfo(client_no);
 
 		int i = 0;
-		if (_network_own_client_index != ci->client_index) {
+		if (_network_own_client_id != ci->client_id) {
 			GetString(this->action[i], STR_NETWORK_CLIENTLIST_SPEAK_TO_CLIENT, lastof(this->action[i]));
 			this->proc[i++] = &ClientList_SpeakToClient;
 		}
@@ -1500,7 +1500,7 @@ struct NetworkClientListPopupWindow : Window {
 		GetString(this->action[i], STR_NETWORK_CLIENTLIST_SPEAK_TO_ALL, lastof(this->action[i]));
 		this->proc[i++] = &ClientList_SpeakToAll;
 
-		if (_network_own_client_index != ci->client_index) {
+		if (_network_own_client_id != ci->client_id) {
 			/* We are no spectator and the company we want to give money to is no spectator and money gifts are allowed */
 			if (IsValidCompanyID(_network_playas) && IsValidCompanyID(ci->client_playas) && _settings_game.economy.give_money) {
 				GetString(this->action[i], STR_NETWORK_CLIENTLIST_GIVE_MONEY, lastof(this->action[i]));
@@ -1509,7 +1509,7 @@ struct NetworkClientListPopupWindow : Window {
 		}
 
 		/* A server can kick clients (but not himself) */
-		if (_network_server && _network_own_client_index != ci->client_index) {
+		if (_network_server && _network_own_client_id != ci->client_id) {
 			GetString(this->action[i], STR_NETWORK_CLIENTLIST_KICK, lastof(this->action[i]));
 			this->proc[i++] = &ClientList_Kick;
 
@@ -1684,7 +1684,7 @@ struct NetworkClientListWindow : Window
 				colour = TC_BLACK;
 			}
 
-			if (ci->client_index == NETWORK_SERVER_INDEX) {
+			if (ci->client_id == CLIENT_ID_SERVER) {
 				DrawString(4, y, STR_NETWORK_SERVER, colour);
 			} else {
 				DrawString(4, y, STR_NETWORK_CLIENT, colour);
diff --git a/src/network/network_internal.h b/src/network/network_internal.h
index 37354cb5e..0508e4eb8 100644
--- a/src/network/network_internal.h
+++ b/src/network/network_internal.h
@@ -144,7 +144,7 @@ void CDECL NetworkTextMessage(NetworkAction action, ConsoleColour color, bool se
 void NetworkGetClientName(char *clientname, size_t size, const NetworkTCPSocketHandler *cs);
 uint NetworkCalculateLag(const NetworkTCPSocketHandler *cs);
 byte NetworkGetCurrentLanguageIndex();
-NetworkTCPSocketHandler *NetworkFindClientStateFromIndex(uint16 client_index);
+NetworkTCPSocketHandler *NetworkFindClientStateFromClientID(ClientID client_id);
 char* GetNetworkErrorMsg(char* buf, NetworkErrorCode err, const char* last);
 bool NetworkFindName(char new_name[NETWORK_CLIENT_NAME_LENGTH]);
 
diff --git a/src/network/network_server.cpp b/src/network/network_server.cpp
index f337fcad2..0a4f35b4a 100644
--- a/src/network/network_server.cpp
+++ b/src/network/network_server.cpp
@@ -46,14 +46,14 @@ DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_CLIENT_INFO)(NetworkTCPSocketHandler
 	// Packet: SERVER_CLIENT_INFO
 	// Function: Sends info about a client
 	// Data:
-	//    uint16:  The index of the client (always unique on a server. 1 = server)
+	//    uint32:  The identifier of the client (always unique on a server. 1 = server, 0 is invalid)
 	//    uint8:  As which company the client is playing
 	//    String: The name of the client
 	//
 
-	if (ci->client_index != NETWORK_EMPTY_INDEX) {
+	if (ci->client_id != INVALID_CLIENT_ID) {
 		Packet *p = NetworkSend_Init(PACKET_SERVER_CLIENT_INFO);
-		p->Send_uint16(ci->client_index);
+		p->Send_uint32(ci->client_id);
 		p->Send_uint8 (ci->client_playas);
 		p->Send_string(ci->client_name);
 
@@ -165,11 +165,11 @@ DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_ERROR)(NetworkTCPSocketHandler *cs,
 				if (error == NETWORK_ERROR_NOT_AUTHORIZED || error == NETWORK_ERROR_NOT_EXPECTED || error == NETWORK_ERROR_WRONG_REVISION)
 					error = NETWORK_ERROR_ILLEGAL_PACKET;
 
-				SEND_COMMAND(PACKET_SERVER_ERROR_QUIT)(new_cs, cs->index, error);
+				SEND_COMMAND(PACKET_SERVER_ERROR_QUIT)(new_cs, cs->client_id, error);
 			}
 		}
 	} else {
-		DEBUG(net, 1, "Client %d made an error and has been disconnected. Reason: '%s'", cs->index, str);
+		DEBUG(net, 1, "Client %d made an error and has been disconnected. Reason: '%s'", cs->client_id, str);
 	}
 
 	cs->has_quit = true;
@@ -236,7 +236,7 @@ DEF_SERVER_SEND_COMMAND(PACKET_SERVER_WELCOME)
 	// Packet: SERVER_WELCOME
 	// Function: The client is joined and ready to receive his map
 	// Data:
-	//    uint16:  Own ClientID
+	//    uint32:  Own Client identifier
 	//
 
 	Packet *p;
@@ -249,7 +249,7 @@ DEF_SERVER_SEND_COMMAND(PACKET_SERVER_WELCOME)
 	_network_game_info.clients_on++;
 
 	p = NetworkSend_Init(PACKET_SERVER_WELCOME);
-	p->Send_uint16(cs->index);
+	p->Send_uint32(cs->client_id);
 	p->Send_uint32(_settings_game.game_creation.generation_seed);
 	p->Send_string(_settings_client.network.network_id);
 	cs->Send_Packet(p);
@@ -260,7 +260,7 @@ DEF_SERVER_SEND_COMMAND(PACKET_SERVER_WELCOME)
 			SEND_COMMAND(PACKET_SERVER_CLIENT_INFO)(cs, DEREF_CLIENT_INFO(new_cs));
 	}
 	// Also send the info of the server
-	SEND_COMMAND(PACKET_SERVER_CLIENT_INFO)(cs, NetworkFindClientInfoFromIndex(NETWORK_SERVER_INDEX));
+	SEND_COMMAND(PACKET_SERVER_CLIENT_INFO)(cs, NetworkFindClientInfoFromIndex(CLIENT_ID_SERVER));
 }
 
 DEF_SERVER_SEND_COMMAND(PACKET_SERVER_WAIT)
@@ -402,7 +402,7 @@ DEF_SERVER_SEND_COMMAND(PACKET_SERVER_MAP)
 	}
 }
 
-DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_JOIN)(NetworkTCPSocketHandler *cs, uint16 client_index)
+DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_JOIN)(NetworkTCPSocketHandler *cs, ClientID client_id)
 {
 	//
 	// Packet: SERVER_JOIN
@@ -410,12 +410,12 @@ DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_JOIN)(NetworkTCPSocketHandler *cs, u
 	//     PACKET_CLIENT_MAP_OK) Mostly what directly follows is a
 	//     PACKET_SERVER_CLIENT_INFO
 	// Data:
-	//    uint16:  Client-Index
+	//    uint32:  Client-identifier
 	//
 
 	Packet *p = NetworkSend_Init(PACKET_SERVER_JOIN);
 
-	p->Send_uint16(client_index);
+	p->Send_uint32(client_id);
 
 	cs->Send_Packet(p);
 }
@@ -499,60 +499,60 @@ DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_COMMAND)(NetworkTCPSocketHandler *cs
 	cs->Send_Packet(p);
 }
 
-DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_CHAT)(NetworkTCPSocketHandler *cs, NetworkAction action, uint16 client_index, bool self_send, const char *msg)
+DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_CHAT)(NetworkTCPSocketHandler *cs, NetworkAction action, ClientID client_id, bool self_send, const char *msg)
 {
 	//
 	// Packet: SERVER_CHAT
 	// Function: Sends a chat-packet to the client
 	// Data:
 	//    uint8:  ActionID (see network_data.h, NetworkAction)
-	//    uint16:  Client-index
+	//    uint32:  Client-identifier
 	//    String: Message (max NETWORK_CHAT_LENGTH)
 	//
 
 	Packet *p = NetworkSend_Init(PACKET_SERVER_CHAT);
 
 	p->Send_uint8 (action);
-	p->Send_uint16(client_index);
+	p->Send_uint32(client_id);
 	p->Send_bool  (self_send);
 	p->Send_string(msg);
 
 	cs->Send_Packet(p);
 }
 
-DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_ERROR_QUIT)(NetworkTCPSocketHandler *cs, uint16 client_index, NetworkErrorCode errorno)
+DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_ERROR_QUIT)(NetworkTCPSocketHandler *cs, ClientID client_id, NetworkErrorCode errorno)
 {
 	//
 	// Packet: SERVER_ERROR_QUIT
 	// Function: One of the clients made an error and is quiting the game
 	//      This packet informs the other clients of that.
 	// Data:
-	//    uint16:  Client-index
+	//    uint32:  Client-identifier
 	//    uint8:  ErrorID (see network_data.h, NetworkErrorCode)
 	//
 
 	Packet *p = NetworkSend_Init(PACKET_SERVER_ERROR_QUIT);
 
-	p->Send_uint16(client_index);
+	p->Send_uint32(client_id);
 	p->Send_uint8 (errorno);
 
 	cs->Send_Packet(p);
 }
 
-DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_QUIT)(NetworkTCPSocketHandler *cs, uint16 client_index, const char *leavemsg)
+DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_QUIT)(NetworkTCPSocketHandler *cs, ClientID client_id, const char *leavemsg)
 {
 	//
 	// Packet: SERVER_ERROR_QUIT
 	// Function: A client left the game, and this packets informs the other clients
 	//      of that.
 	// Data:
-	//    uint16:  Client-index
+	//    uint32:  Client-identifier
 	//    String: leave-message
 	//
 
 	Packet *p = NetworkSend_Init(PACKET_SERVER_QUIT);
 
-	p->Send_uint16(client_index);
+	p->Send_uint32(client_id);
 	p->Send_string(leavemsg);
 
 	cs->Send_Packet(p);
@@ -800,7 +800,7 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_MAP_OK)
 		FOR_ALL_CLIENTS(new_cs) {
 			if (new_cs->status > STATUS_AUTH) {
 				SEND_COMMAND(PACKET_SERVER_CLIENT_INFO)(new_cs, DEREF_CLIENT_INFO(cs));
-				SEND_COMMAND(PACKET_SERVER_JOIN)(new_cs, cs->index);
+				SEND_COMMAND(PACKET_SERVER_JOIN)(new_cs, cs->client_id);
 			}
 		}
 
@@ -808,7 +808,7 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_MAP_OK)
 			/* Now pause the game till the client is in sync */
 			DoCommandP(0, 1, 0, NULL, CMD_PAUSE);
 
-			NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game paused (incoming client)", NETWORK_SERVER_INDEX);
+			NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game paused (incoming client)", CLIENT_ID_SERVER);
 		}
 	} else {
 		// Wrong status for this packet, give a warning to client, and close connection
@@ -825,18 +825,18 @@ static bool CheckCommandFlags(const CommandPacket *cp, const NetworkClientInfo *
 {
 	byte flags = GetCommandFlags(cp->cmd);
 
-	if (flags & CMD_SERVER && ci->client_index != NETWORK_SERVER_INDEX) {
-		IConsolePrintF(CC_ERROR, "WARNING: server only command from client %d (IP: %s), kicking...", ci->client_index, GetClientIP(ci));
+	if (flags & CMD_SERVER && ci->client_id != CLIENT_ID_SERVER) {
+		IConsolePrintF(CC_ERROR, "WARNING: server only command from client %d (IP: %s), kicking...", ci->client_id, GetClientIP(ci));
 		return false;
 	}
 
 	if (flags & CMD_OFFLINE) {
-		IConsolePrintF(CC_ERROR, "WARNING: offline only command from client %d (IP: %s), kicking...", ci->client_index, GetClientIP(ci));
+		IConsolePrintF(CC_ERROR, "WARNING: offline only command from client %d (IP: %s), kicking...", ci->client_id, GetClientIP(ci));
 		return false;
 	}
 
-	if (cp->cmd != CMD_COMPANY_CTRL && !IsValidCompanyID(cp->company) && ci->client_index != NETWORK_SERVER_INDEX) {
-		IConsolePrintF(CC_ERROR, "WARNING: spectator issueing command from client %d (IP: %s), kicking...", ci->client_index, GetClientIP(ci));
+	if (cp->cmd != CMD_COMPANY_CTRL && !IsValidCompanyID(cp->company) && ci->client_id != CLIENT_ID_SERVER) {
+		IConsolePrintF(CC_ERROR, "WARNING: spectator issueing command from client %d (IP: %s), kicking...", ci->client_id, GetClientIP(ci));
 		return false;
 	}
 
@@ -879,7 +879,7 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_COMMAND)
 
 	/* Check if cp->cmd is valid */
 	if (!IsValidCommand(cp->cmd)) {
-		IConsolePrintF(CC_ERROR, "WARNING: invalid command from client %d (IP: %s).", ci->client_index, GetClientIP(ci));
+		IConsolePrintF(CC_ERROR, "WARNING: invalid command from client %d (IP: %s).", ci->client_id, GetClientIP(ci));
 		SEND_COMMAND(PACKET_SERVER_ERROR)(cs, NETWORK_ERROR_NOT_EXPECTED);
 		free(cp);
 		return;
@@ -977,7 +977,7 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_ERROR)
 
 	FOR_ALL_CLIENTS(new_cs) {
 		if (new_cs->status > STATUS_AUTH) {
-			SEND_COMMAND(PACKET_SERVER_ERROR_QUIT)(new_cs, cs->index, errorno);
+			SEND_COMMAND(PACKET_SERVER_ERROR_QUIT)(new_cs, cs->client_id, errorno);
 		}
 	}
 
@@ -1006,7 +1006,7 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_QUIT)
 
 	FOR_ALL_CLIENTS(new_cs) {
 		if (new_cs->status > STATUS_AUTH) {
-			SEND_COMMAND(PACKET_SERVER_QUIT)(new_cs, cs->index, str);
+			SEND_COMMAND(PACKET_SERVER_QUIT)(new_cs, cs->client_id, str);
 		}
 	}
 
@@ -1033,7 +1033,7 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_ACK)
 
 		if (_settings_client.network.pause_on_join) {
 			DoCommandP(0, 0, 0, NULL, CMD_PAUSE);
-			NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game unpaused (client connected)", NETWORK_SERVER_INDEX);
+			NetworkServerSendChat(NETWORK_ACTION_SERVER_MESSAGE, DESTTYPE_BROADCAST, 0, "Game unpaused (client connected)", CLIENT_ID_SERVER);
 		}
 
 		CheckMinActiveClients();
@@ -1050,7 +1050,7 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_ACK)
 
 
 
-void NetworkServerSendChat(NetworkAction action, DestType desttype, int dest, const char *msg, uint16 from_index)
+void NetworkServerSendChat(NetworkAction action, DestType desttype, int dest, const char *msg, ClientID from_id)
 {
 	NetworkTCPSocketHandler *cs;
 	const NetworkClientInfo *ci, *ci_own, *ci_to;
@@ -1058,32 +1058,32 @@ void NetworkServerSendChat(NetworkAction action, DestType desttype, int dest, co
 	switch (desttype) {
 	case DESTTYPE_CLIENT:
 		/* Are we sending to the server? */
-		if (dest == NETWORK_SERVER_INDEX) {
-			ci = NetworkFindClientInfoFromIndex(from_index);
+		if ((ClientID)dest == CLIENT_ID_SERVER) {
+			ci = NetworkFindClientInfoFromIndex(from_id);
 			/* Display the text locally, and that is it */
 			if (ci != NULL)
 				NetworkTextMessage(action, (ConsoleColour)GetDrawStringCompanyColor(ci->client_playas), false, ci->client_name, "%s", msg);
 		} else {
 			/* Else find the client to send the message to */
 			FOR_ALL_CLIENTS(cs) {
-				if (cs->index == dest) {
-					SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, from_index, false, msg);
+				if (cs->client_id == (ClientID)dest) {
+					SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, from_id, false, msg);
 					break;
 				}
 			}
 		}
 
 		// Display the message locally (so you know you have sent it)
-		if (from_index != dest) {
-			if (from_index == NETWORK_SERVER_INDEX) {
-				ci = NetworkFindClientInfoFromIndex(from_index);
-				ci_to = NetworkFindClientInfoFromIndex(dest);
+		if (from_id != (ClientID)dest) {
+			if (from_id == CLIENT_ID_SERVER) {
+				ci = NetworkFindClientInfoFromIndex(from_id);
+				ci_to = NetworkFindClientInfoFromIndex((ClientID)dest);
 				if (ci != NULL && ci_to != NULL)
 					NetworkTextMessage(action, (ConsoleColour)GetDrawStringCompanyColor(ci->client_playas), true, ci_to->client_name, "%s", msg);
 			} else {
 				FOR_ALL_CLIENTS(cs) {
-					if (cs->index == from_index) {
-						SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, dest, true, msg);
+					if (cs->client_id == from_id) {
+						SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, (ClientID)dest, true, msg);
 						break;
 					}
 				}
@@ -1097,18 +1097,18 @@ void NetworkServerSendChat(NetworkAction action, DestType desttype, int dest, co
 		ci_to = NULL;
 		FOR_ALL_CLIENTS(cs) {
 			ci = DEREF_CLIENT_INFO(cs);
-			if (ci->client_playas == dest) {
-				SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, from_index, false, msg);
-				if (cs->index == from_index) show_local = false;
+			if (ci->client_playas == (CompanyID)dest) {
+				SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, from_id, false, msg);
+				if (cs->client_id == from_id) show_local = false;
 				ci_to = ci; // Remember a client that is in the company for company-name
 			}
 		}
 
-		ci = NetworkFindClientInfoFromIndex(from_index);
-		ci_own = NetworkFindClientInfoFromIndex(NETWORK_SERVER_INDEX);
+		ci = NetworkFindClientInfoFromIndex(from_id);
+		ci_own = NetworkFindClientInfoFromIndex(CLIENT_ID_SERVER);
 		if (ci != NULL && ci_own != NULL && ci_own->client_playas == dest) {
 			NetworkTextMessage(action, (ConsoleColour)GetDrawStringCompanyColor(ci->client_playas), false, ci->client_name, "%s", msg);
-			if (from_index == NETWORK_SERVER_INDEX) show_local = false;
+			if (from_id == CLIENT_ID_SERVER) show_local = false;
 			ci_to = ci_own;
 		}
 
@@ -1117,7 +1117,7 @@ void NetworkServerSendChat(NetworkAction action, DestType desttype, int dest, co
 
 		// Display the message locally (so you know you have sent it)
 		if (ci != NULL && show_local) {
-			if (from_index == NETWORK_SERVER_INDEX) {
+			if (from_id == CLIENT_ID_SERVER) {
 				char name[NETWORK_NAME_LENGTH];
 				StringID str = IsValidCompanyID(ci_to->client_playas) ? STR_COMPANY_NAME : STR_NETWORK_SPECTATORS;
 				SetDParam(0, ci_to->client_playas);
@@ -1125,8 +1125,8 @@ void NetworkServerSendChat(NetworkAction action, DestType desttype, int dest, co
 				NetworkTextMessage(action, (ConsoleColour)GetDrawStringCompanyColor(ci_own->client_playas), true, name, "%s", msg);
 			} else {
 				FOR_ALL_CLIENTS(cs) {
-					if (cs->index == from_index) {
-						SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, ci_to->client_index, true, msg);
+					if (cs->client_id == from_id) {
+						SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, ci_to->client_id, true, msg);
 					}
 				}
 			}
@@ -1138,9 +1138,9 @@ void NetworkServerSendChat(NetworkAction action, DestType desttype, int dest, co
 		/* fall-through to next case */
 	case DESTTYPE_BROADCAST:
 		FOR_ALL_CLIENTS(cs) {
-			SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, from_index, false, msg);
+			SEND_COMMAND(PACKET_SERVER_CHAT)(cs, action, from_id, false, msg);
 		}
-		ci = NetworkFindClientInfoFromIndex(from_index);
+		ci = NetworkFindClientInfoFromIndex(from_id);
 		if (ci != NULL)
 			NetworkTextMessage(action, (ConsoleColour)GetDrawStringCompanyColor(ci->client_playas), false, ci->client_name, "%s", msg);
 		break;
@@ -1157,7 +1157,7 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_CHAT)
 
 	NetworkAction action = (NetworkAction)p->Recv_uint8();
 	DestType desttype = (DestType)p->Recv_uint8();
-	int dest = p->Recv_uint16();
+	int dest = p->Recv_uint32();
 	char msg[NETWORK_CHAT_LENGTH];
 
 	p->Recv_string(msg, NETWORK_CHAT_LENGTH);
@@ -1170,10 +1170,10 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_CHAT)
 		case NETWORK_ACTION_CHAT:
 		case NETWORK_ACTION_CHAT_CLIENT:
 		case NETWORK_ACTION_CHAT_COMPANY:
-			NetworkServerSendChat(action, desttype, dest, msg, cs->index);
+			NetworkServerSendChat(action, desttype, dest, msg, cs->client_id);
 			break;
 		default:
-			IConsolePrintF(CC_ERROR, "WARNING: invalid chat action from client %d (IP: %s).", ci->client_index, GetClientIP(ci));
+			IConsolePrintF(CC_ERROR, "WARNING: invalid chat action from client %d (IP: %s).", ci->client_id, GetClientIP(ci));
 			SEND_COMMAND(PACKET_SERVER_ERROR)(cs, NETWORK_ERROR_NOT_EXPECTED);
 			break;
 	}
@@ -1219,7 +1219,7 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_SET_NAME)
 		if (NetworkFindName(client_name)) {
 			NetworkTextMessage(NETWORK_ACTION_NAME_CHANGE, CC_DEFAULT, false, ci->client_name, "%s", client_name);
 			strecpy(ci->client_name, client_name, lastof(ci->client_name));
-			NetworkUpdateClientInfo(ci->client_index);
+			NetworkUpdateClientInfo(ci->client_id);
 		}
 	}
 }
@@ -1235,15 +1235,15 @@ DEF_SERVER_RECEIVE_COMMAND(PACKET_CLIENT_RCON)
 	p->Recv_string(command, sizeof(command));
 
 	if (strcmp(pass, _settings_client.network.rcon_password) != 0) {
-		DEBUG(net, 0, "[rcon] wrong password from client-id %d", cs->index);
+		DEBUG(net, 0, "[rcon] wrong password from client-id %d", cs->client_id);
 		return;
 	}
 
-	DEBUG(net, 0, "[rcon] client-id %d executed: '%s'", cs->index, command);
+	DEBUG(net, 0, "[rcon] client-id %d executed: '%s'", cs->client_id, command);
 
-	_redirect_console_to_client = cs->index;
+	_redirect_console_to_client = cs->client_id;
 	IConsoleCmdExec(command);
-	_redirect_console_to_client = 0;
+	_redirect_console_to_client = INVALID_CLIENT_ID;
 	return;
 }
 
@@ -1369,7 +1369,7 @@ void NetworkPopulateCompanyInfo()
 		}
 	}
 
-	ci = NetworkFindClientInfoFromIndex(NETWORK_SERVER_INDEX);
+	ci = NetworkFindClientInfoFromIndex(CLIENT_ID_SERVER);
 	// Register local company (if not dedicated)
 	if (ci != NULL && IsValidCompanyID(ci->client_playas))
 		strecpy(_network_company_info[ci->client_playas].clients, ci->client_name, lastof(_network_company_info[ci->client_playas].clients));
@@ -1390,11 +1390,11 @@ void NetworkPopulateCompanyInfo()
 	}
 }
 
-// Send a packet to all clients with updated info about this client_index
-void NetworkUpdateClientInfo(uint16 client_index)
+// Send a packet to all clients with updated info about this client_id
+void NetworkUpdateClientInfo(ClientID client_id)
 {
 	NetworkTCPSocketHandler *cs;
-	NetworkClientInfo *ci = NetworkFindClientInfoFromIndex(client_index);
+	NetworkClientInfo *ci = NetworkFindClientInfoFromIndex(client_id);
 
 	if (ci == NULL) return;
 
@@ -1436,7 +1436,7 @@ static void NetworkAutoCleanCompanies()
 	}
 
 	if (!_network_dedicated) {
-		ci = NetworkFindClientInfoFromIndex(NETWORK_SERVER_INDEX);
+		ci = NetworkFindClientInfoFromIndex(CLIENT_ID_SERVER);
 		if (IsValidCompanyID(ci->client_playas)) clients_in_company[ci->client_playas] = true;
 	}
 
@@ -1494,7 +1494,7 @@ bool NetworkFindName(char new_name[NETWORK_CLIENT_NAME_LENGTH])
 			}
 		}
 		// Check if it is the same as the server-name
-		ci = NetworkFindClientInfoFromIndex(NETWORK_SERVER_INDEX);
+		ci = NetworkFindClientInfoFromIndex(CLIENT_ID_SERVER);
 		if (ci != NULL) {
 			if (strcmp(ci->client_name, new_name) == 0) found_name = false; // name already in use
 		}
@@ -1568,14 +1568,14 @@ void NetworkServer_Tick(bool send_frame)
 				if (lag > 3) {
 					// Client did still not report in after 4 game-day, drop him
 					//  (that is, the 3 of above, + 1 before any lag is counted)
-					IConsolePrintF(CC_ERROR,"Client #%d is dropped because the client did not respond for more than 4 game-days", cs->index);
+					IConsolePrintF(CC_ERROR,"Client #%d is dropped because the client did not respond for more than 4 game-days", cs->client_id);
 					NetworkCloseClient(cs);
 					continue;
 				}
 
 				// Report once per time we detect the lag
 				if (cs->lag_test == 0) {
-					IConsolePrintF(CC_WARNING,"[%d] Client #%d is slow, try increasing *net_frame_freq to a higher value!", _frame_counter, cs->index);
+					IConsolePrintF(CC_WARNING,"[%d] Client #%d is slow, try increasing *net_frame_freq to a higher value!", _frame_counter, cs->client_id);
 					cs->lag_test = 1;
 				}
 			} else {
@@ -1584,13 +1584,13 @@ void NetworkServer_Tick(bool send_frame)
 		} else if (cs->status == STATUS_PRE_ACTIVE) {
 			int lag = NetworkCalculateLag(cs);
 			if (lag > _settings_client.network.max_join_time) {
-				IConsolePrintF(CC_ERROR,"Client #%d is dropped because it took longer than %d ticks for him to join", cs->index, _settings_client.network.max_join_time);
+				IConsolePrintF(CC_ERROR,"Client #%d is dropped because it took longer than %d ticks for him to join", cs->client_id, _settings_client.network.max_join_time);
 				NetworkCloseClient(cs);
 			}
 		} else if (cs->status == STATUS_INACTIVE) {
 			int lag = NetworkCalculateLag(cs);
 			if (lag > 4 * DAY_TICKS) {
-				IConsolePrintF(CC_ERROR,"Client #%d is dropped because it took longer than %d ticks to start the joining process", cs->index, 4 * DAY_TICKS);
+				IConsolePrintF(CC_ERROR,"Client #%d is dropped because it took longer than %d ticks to start the joining process", cs->client_id, 4 * DAY_TICKS);
 				NetworkCloseClient(cs);
 			}
 		}
@@ -1628,12 +1628,12 @@ void NetworkServerChangeOwner(Owner current_owner, Owner new_owner)
 	/* The server has to handle all administrative issues, for example
 	 * updating and notifying all clients of what has happened */
 	NetworkTCPSocketHandler *cs;
-	NetworkClientInfo *ci = NetworkFindClientInfoFromIndex(NETWORK_SERVER_INDEX);
+	NetworkClientInfo *ci = NetworkFindClientInfoFromIndex(CLIENT_ID_SERVER);
 
 	/* The server has just changed from owner */
 	if (current_owner == ci->client_playas) {
 		ci->client_playas = new_owner;
-		NetworkUpdateClientInfo(NETWORK_SERVER_INDEX);
+		NetworkUpdateClientInfo(CLIENT_ID_SERVER);
 	}
 
 	/* Find all clients that were in control of this company, and mark them as new_owner */
@@ -1641,7 +1641,7 @@ void NetworkServerChangeOwner(Owner current_owner, Owner new_owner)
 		ci = DEREF_CLIENT_INFO(cs);
 		if (current_owner == ci->client_playas) {
 			ci->client_playas = new_owner;
-			NetworkUpdateClientInfo(ci->client_index);
+			NetworkUpdateClientInfo(ci->client_id);
 		}
 	}
 }
@@ -1675,20 +1675,20 @@ void NetworkServerShowStatusToConsole()
 
 		status = (cs->status < (ptrdiff_t)lengthof(stat_str) ? stat_str[cs->status] : "unknown");
 		IConsolePrintF(CC_INFO, "Client #%1d  name: '%s'  status: '%s'  frame-lag: %3d  company: %1d  IP: %s  unique-id: '%s'",
-			cs->index, ci->client_name, status, lag,
+			cs->client_id, ci->client_name, status, lag,
 			ci->client_playas + (IsValidCompanyID(ci->client_playas) ? 1 : 0),
 			GetClientIP(ci), ci->unique_id);
 	}
 }
 
-void NetworkServerSendRcon(uint16 client_index, ConsoleColour colour_code, const char *string)
+void NetworkServerSendRcon(ClientID client_id, ConsoleColour colour_code, const char *string)
 {
-	SEND_COMMAND(PACKET_SERVER_RCON)(NetworkFindClientStateFromIndex(client_index), colour_code, string);
+	SEND_COMMAND(PACKET_SERVER_RCON)(NetworkFindClientStateFromClientID(client_id), colour_code, string);
 }
 
-void NetworkServerSendError(uint16 client_index, NetworkErrorCode error)
+void NetworkServerSendError(ClientID client_id, NetworkErrorCode error)
 {
-	SEND_COMMAND(PACKET_SERVER_ERROR)(NetworkFindClientStateFromIndex(client_index), error);
+	SEND_COMMAND(PACKET_SERVER_ERROR)(NetworkFindClientStateFromClientID(client_id), error);
 }
 
 bool NetworkCompanyHasClients(CompanyID company)
diff --git a/src/network/network_server.h b/src/network/network_server.h
index 3b5b02fef..620fed36b 100644
--- a/src/network/network_server.h
+++ b/src/network/network_server.h
@@ -8,7 +8,7 @@
 #ifdef ENABLE_NETWORK
 
 DEF_SERVER_SEND_COMMAND(PACKET_SERVER_MAP);
-DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_ERROR_QUIT)(NetworkTCPSocketHandler *cs, uint16 client_index, NetworkErrorCode errorno);
+DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_ERROR_QUIT)(NetworkTCPSocketHandler *cs, ClientID client_id, NetworkErrorCode errorno);
 DEF_SERVER_SEND_COMMAND_PARAM(PACKET_SERVER_ERROR)(NetworkTCPSocketHandler *cs, NetworkErrorCode error);
 DEF_SERVER_SEND_COMMAND(PACKET_SERVER_SHUTDOWN);
 DEF_SERVER_SEND_COMMAND(PACKET_SERVER_NEWGAME);
diff --git a/src/network/network_type.h b/src/network/network_type.h
index c26c84738..1f14607d8 100644
--- a/src/network/network_type.h
+++ b/src/network/network_type.h
@@ -20,18 +20,25 @@ enum {
 	 */
 	MAX_CLIENTS = MAX_COMPANIES + 3,
 
-	/** Do not change this next line. It should _ALWAYS_ be MAX_CLIENTS + 1 */
-	MAX_CLIENT_INFO = MAX_CLIENTS + 1,
-
 	/** Maximum number of internet interfaces supported. */
 	MAX_INTERFACES = 9,
 
 	/** How many vehicle/station types we put over the network */
 	NETWORK_VEHICLE_TYPES = 5,
 	NETWORK_STATION_TYPES = 5,
+};
 
-	NETWORK_SERVER_INDEX = 1,
-	NETWORK_EMPTY_INDEX  = 0,
+/** 'Unique' identifier to be given to clients */
+enum ClientID {
+	INVALID_CLIENT_ID = 0, ///< Client is not part of anything
+	CLIENT_ID_SERVER  = 1, ///< Servers always have this ID
+	CLIENT_ID_FIRST   = 2, ///< The first client ID
+};
+
+/** Indices into the client tables */
+enum ClientIndex {
+	/** Do not change this next line. It should _ALWAYS_ be MAX_CLIENTS + 1 */
+	MAX_CLIENT_INFO = MAX_CLIENTS + 1,
 };
 
 struct NetworkCompanyInfo {
@@ -50,7 +57,7 @@ struct NetworkCompanyInfo {
 };
 
 struct NetworkClientInfo {
-	uint16 client_index;                            ///< Index of the client (same as ClientState->index)
+	ClientID client_id;                             ///< Client identifier (same as ClientState->client_id)
 	char client_name[NETWORK_CLIENT_NAME_LENGTH];   ///< Name of the client
 	byte client_lang;                               ///< The language of the client
 	CompanyID client_playas;                        ///< As which company is this client playing (CompanyID)