Feature: authorize specific clients to join network company without password

src/lang/english.txt

@@ -2487,6 +2487,7 @@ STR_NETWORK_CLIENT_LIST_PLAYER_NAME_QUERY_CAPTION               :Your player nam
 STR_NETWORK_CLIENT_LIST_ADMIN_CLIENT_TOOLTIP                    :{BLACK}Administrative actions to perform for this client
 STR_NETWORK_CLIENT_LIST_ADMIN_COMPANY_TOOLTIP                   :{BLACK}Administrative actions to perform for this company
 STR_NETWORK_CLIENT_LIST_JOIN_TOOLTIP                            :{BLACK}Join this company
+STR_NETWORK_CLIENT_LIST_COMPANY_AUTHORIZE_TOOLTIP               :{BLACK}Authorize this client to join your company
 STR_NETWORK_CLIENT_LIST_CHAT_CLIENT_TOOLTIP                     :{BLACK}Send a message to this player
 STR_NETWORK_CLIENT_LIST_CHAT_COMPANY_TOOLTIP                    :{BLACK}Send a message to all players of this company
 STR_NETWORK_CLIENT_LIST_CHAT_SPECTATOR_TOOLTIP                  :{BLACK}Send a message to all spectators

src/network/network.cpp

@@ -126,6 +126,28 @@ NetworkClientInfo::~NetworkClientInfo()
 	return nullptr;
 }
 
+/**
+ * Returns whether the given company can be joined by this client.
+ * @param company_id The id of the company.
+ * @return \c true when this company is allowed to join, otherwise \c false.
+ */
+bool NetworkClientInfo::CanJoinCompany(CompanyID company_id) const
+{
+	Company *c = Company::GetIfValid(company_id);
+	return c != nullptr && c->allow_list.Contains(this->public_key);
+}
+
+/**
+ * Returns whether the given company can be joined by this client.
+ * @param company_id The id of the company.
+ * @return \c true when this company is allowed to join, otherwise \c false.
+ */
+bool NetworkCanJoinCompany(CompanyID company_id)
+{
+	NetworkClientInfo *info = NetworkClientInfo::GetByClientID(_network_own_client_id);
+	return info != nullptr && info->CanJoinCompany(company_id);
+}
+
 /**
  * Return the client state given it's client-identifier
  * @param client_id the ClientID to search for
@@ -889,6 +911,9 @@ static void NetworkInitGameInfo()
 	ci->client_playas = COMPANY_SPECTATOR;
 
 	ci->client_name = _settings_client.network.client_name;
+
+	NetworkAuthenticationClientHandler::EnsureValidSecretKeyAndUpdatePublicKey(_settings_client.network.client_secret_key, _settings_client.network.client_public_key);
+	ci->public_key = _settings_client.network.client_public_key;
 }
 
 /**

src/network/network_base.h

@@ -36,6 +36,8 @@ struct NetworkClientInfo : NetworkClientInfoPool::PoolItem<&_networkclientinfo_p
 	~NetworkClientInfo();
 
 	static NetworkClientInfo *GetByClientID(ClientID client_id);
+
+	bool CanJoinCompany(CompanyID company_id) const;
 };
 
 #endif /* NETWORK_BASE_H */

src/network/network_crypto.cpp

@@ -443,6 +443,15 @@ void CombinedAuthenticationServerHandler::Add(CombinedAuthenticationServerHandle
 	this->SendResponse();
 }
 
+/**
+ * Ensures that the given secret key is valid, and when not overwrite it with a valid secret key. Then update the public key to be associated with the secret key.
+ * @param secret_key The location where the secret key is stored; can be overwritten when invalid.
+ * @param public_key The location where the public key is stored; can be overwritten when invalid.
+ */
+/* static */ void NetworkAuthenticationClientHandler::EnsureValidSecretKeyAndUpdatePublicKey(std::string &secret_key, std::string &public_key)
+{
+	X25519AuthorizedKeyClientHandler::GetValidSecretKeyAndUpdatePublicKey(secret_key, public_key);
+}
 
 /**
  * Create a NetworkAuthenticationClientHandler.

src/network/network_crypto.h

@@ -248,6 +248,7 @@ public:
 	 */
 	virtual bool ReceiveEnableEncryption(struct Packet &p) = 0;
 
+	static void EnsureValidSecretKeyAndUpdatePublicKey(std::string &secret_key, std::string &public_key);
 	static std::unique_ptr<NetworkAuthenticationClientHandler> Create(std::shared_ptr<NetworkAuthenticationPasswordRequestHandler> password_handler, std::string &secret_key, std::string &public_key);
 };
 

src/network/network_func.h

@@ -75,6 +75,7 @@ void NetworkServerNewCompany(const Company *company, NetworkClientInfo *ci);
 bool NetworkServerChangeClientName(ClientID client_id, const std::string &new_name);
 
 
+bool NetworkCanJoinCompany(CompanyID company_id);
 void NetworkServerDoMove(ClientID client_id, CompanyID company_id);
 void NetworkServerSendRcon(ClientID client_id, TextColour colour_code, const std::string &string);
 void NetworkServerSendChat(NetworkAction action, DestType type, int dest, const std::string &msg, ClientID from_id, int64_t data = 0, bool from_admin = false);

src/network/network_gui.cpp

@@ -1536,6 +1536,12 @@ private:
 		ShowNetworkChatQueryWindow(DESTTYPE_CLIENT, client_id);
 	}
 
+	static void OnClickClientAuthorize([[maybe_unused]] NetworkClientListWindow *w, [[maybe_unused]] Point pt, ClientID client_id)
+	{
+		AutoRestoreBackup<CompanyID> cur_company(_current_company, NetworkClientInfo::GetByClientID(_network_own_client_id)->client_playas);
+		Command<CMD_COMPANY_ADD_ALLOW_LIST>::Post(NetworkClientInfo::GetByClientID(client_id)->public_key);
+	}
+
 	/**
 	 * Part of RebuildList() to create the information for a single company.
 	 * @param company_id The company to build the list for.
@@ -1558,6 +1564,7 @@ private:
 
 			if (_network_server) this->buttons[line_count].push_back(std::make_unique<ClientButton>(SPR_ADMIN, STR_NETWORK_CLIENT_LIST_ADMIN_CLIENT_TOOLTIP, COLOUR_RED, ci->client_id, &NetworkClientListWindow::OnClickClientAdmin, _network_own_client_id == ci->client_id));
 			if (_network_own_client_id != ci->client_id) this->buttons[line_count].push_back(std::make_unique<ClientButton>(SPR_CHAT, STR_NETWORK_CLIENT_LIST_CHAT_CLIENT_TOOLTIP, COLOUR_ORANGE, ci->client_id, &NetworkClientListWindow::OnClickClientChat));
+			if (_network_own_client_id != ci->client_id && client_playas != COMPANY_SPECTATOR && !ci->CanJoinCompany(client_playas)) this->buttons[line_count].push_back(std::make_unique<ClientButton>(SPR_JOIN, STR_NETWORK_CLIENT_LIST_COMPANY_AUTHORIZE_TOOLTIP, COLOUR_GREEN, ci->client_id, &NetworkClientListWindow::OnClickClientAuthorize));
 
 			if (ci->client_id == _network_own_client_id) {
 				this->player_self_index = this->line_count;

src/toolbar_gui.cpp

@@ -97,7 +97,7 @@ static CallBackFunction _last_started_action = CBF_NONE; ///< Last started user
  */
 class DropDownListCompanyItem : public DropDownIcon<DropDownIcon<DropDownString<DropDownListItem>, true>> {
 public:
-	DropDownListCompanyItem(CompanyID company, bool shaded) : DropDownIcon<DropDownIcon<DropDownString<DropDownListItem>, true>>(SPR_COMPANY_ICON, COMPANY_SPRITE_COLOUR(company), NetworkCompanyIsPassworded(company) ? SPR_LOCK : SPR_EMPTY, PAL_NONE, STR_NULL, company, false, shaded)
+	DropDownListCompanyItem(CompanyID company, bool shaded) : DropDownIcon<DropDownIcon<DropDownString<DropDownListItem>, true>>(SPR_COMPANY_ICON, COMPANY_SPRITE_COLOUR(company), NetworkCanJoinCompany(company) ? SPR_EMPTY : SPR_LOCK, PAL_NONE, STR_NULL, company, false, shaded)
 	{
 		SetDParam(0, company);
 		SetDParam(1, company);