Use network protocol variable to connect.

res/localization.csv

@@ -11,8 +11,8 @@ CONNECT_LAYOUT_CONNECT_RESULT_OTHER_ERR,There was an error,Возникла ош
 CONNECT_LAYOUT_CONNECT_RESULT_ERR_SERVER_OFFLINE,"Can't connect to the server. Make sure the specified server and port are correct, otherwise the server might be offline.","Не получается подключиться к серверу. Убедитесь, что указанный сервер и порт корректны, иначе, возможно сервер не запущен."
 CONNECT_LAYOUT_CONNECT_RESULT_ERR_WRONG_PASSWORD_PART1,"Server reply: wrong password, try again after","Ответ сервера: неверный пароль, попробуйте еще раз через"
 CONNECT_LAYOUT_CONNECT_RESULT_ERR_WRONG_PASSWORD_PART2,seconds,секунды
-CONNECT_LAYOUT_CONNECT_RESULT_ERR_WRONG_VERSION_PART1,Server reply: your client version,Ответ сервера: версия вашего приложения
-CONNECT_LAYOUT_CONNECT_RESULT_ERR_WRONG_VERSION_PART2,"is not supported by this server, the server supports version","не поддерживается этим сервером, сервер поддерживает версию"
+CONNECT_LAYOUT_CONNECT_RESULT_ERR_WRONG_VERSION_PART1,Server reply: your client protocol version,Ответ сервера: версия протокола вашего приложения
+CONNECT_LAYOUT_CONNECT_RESULT_ERR_WRONG_VERSION_PART2,"is not supported by this server, the server supports protocol version","не поддерживается этим сервером, сервер поддерживает версию протокола"
 CONNECT_LAYOUT_CONNECT_RESULT_ERR_USERNAME_TAKEN,"Server reply: somebody with your username already persists on the server, please, choose another username.","Ответ сервера: кто-то с вашим именем уже находится на сервере, пожалуйста, выберите другое имя пользователя."
 CONNECT_LAYOUT_CHECK_FIELDS_LENGTH_USERNAME_PART1,The username is too long,Имя пользователя слишком длинное
 CONNECT_LAYOUT_CHECK_FIELDS_LENGTH_USERNAME_PART2,characters when the limit is,"символов, в то время как максимум"

src/global_params.rs

@@ -1,6 +1,7 @@
 pub const CLIENT_CONFIG_FILE_NAME: &str = "silent.config";
 pub const CONFIG_FILE_MAGIC_NUMBER: u16 = 51338;
 pub const CONFIG_FILE_VERSION: u64 = 2;
+pub const NETWORK_PROTOCOL_VERSION: u64 = 0; // server with the same version is considered compatible
 
 pub const TEXT_SIZE: f64 = 18.0;
 pub const MESSAGE_AUTHOR_TEXT_SIZE: f64 = 16.0;

src/layouts/connect_layout.rs

@@ -307,7 +307,7 @@ impl ConnectLayout {
                 .get(LOCALE_CONNECT_LAYOUT_CONNECT_RESULT_ERR_SERVER_OFFLINE)
                 .unwrap()
                 .clone(),
-            ConnectResult::WrongVersion(server_version) => {
+            ConnectResult::WrongProtocol(server_protocol) => {
                 format!(
                     "{} {} {} {}.",
                     localization
@@ -317,7 +317,7 @@ impl ConnectLayout {
                     localization
                         .get(LOCALE_CONNECT_LAYOUT_CONNECT_RESULT_ERR_WRONG_VERSION_PART2)
                         .unwrap(),
-                    server_version
+                    server_protocol
                 )
             }
             ConnectResult::UsernameTaken => localization

src/services/user_tcp_service.rs

@@ -62,6 +62,7 @@ pub enum ClientMessageTcp {
     UserMessage = 0,
     EnterRoom = 1,
     KeepAliveCheck = 2,
+    TryConnect = 3,
 }
 
 pub struct UserMessageInfo {
@@ -91,8 +92,8 @@ pub enum ConnectResult {
     IoErr(IoResult),
     ErrServerOffline,
     UsernameTaken,
-    SleepWithErr(usize),  // sleep time in sec.
-    WrongVersion(String), // needed protocol
+    SleepWithErr(usize), // sleep time in sec.
+    WrongProtocol(u64),  // needed protocol
     Err(String),
     InfoAboutOtherUser(UserInfo, String, u16),
     InfoAboutRoom(String),
@@ -756,25 +757,47 @@ impl UserTcpService {
         info_sender: std::sync::mpsc::Sender<ConnectInfo>,
     ) -> ConnectResult {
         // Prepare initial send buffer:
-        // (u16): size of the version string,
-        // (size): version string,
+        // (u16): message id (TryConnect)
+        // (u64): net protocol version
         // (u16): size of the username,
         // (size): username string,
         // (u16): size of the password string,
         // (size): password string.
-        let ver_str_len = env!("CARGO_PKG_VERSION").len() as u16;
+
+        // Prepare data ID buffer.
+        let data_id = ClientMessageTcp::TryConnect.to_u16();
+        if data_id.is_none() {
+            return ConnectResult::IoErr(IoResult::Err(format!(
+                "ClientMessage::TryConnect.to_u16() failed at [{}, {}]",
+                file!(),
+                line!()
+            )));
+        }
+        let data_id = data_id.unwrap();
+        let data_id_buf = u16::encode::<u16>(&data_id);
+        if let Err(e) = data_id_buf {
+            return ConnectResult::Err(format!(
+                "u16::encode::<u16>() failed on value {}, error: {} at [{}, {}]",
+                data_id,
+                e,
+                file!(),
+                line!()
+            ));
+        }
+        let mut data_id_buf = data_id_buf.unwrap();
+
+        let net_protocol_version = NETWORK_PROTOCOL_VERSION;
         let name_str_len = self.user_info.username.len() as u16;
 
         // Convert to buffers.
-        let mut ver_str_len_buf = u16::encode::<u16>(&ver_str_len).unwrap();
-        let mut ver_str_buf = Vec::from(env!("CARGO_PKG_VERSION").as_bytes());
         let mut name_str_len_buf = u16::encode::<u16>(&name_str_len).unwrap();
+        let mut net_protocol_version_buf = u64::encode::<u64>(&net_protocol_version).unwrap();
         let mut name_str_buf = Vec::from(self.user_info.username.as_bytes());
 
         // Move all buffers to one big buffer.
         let mut out_buffer: Vec<u8> = Vec::new();
-        out_buffer.append(&mut ver_str_len_buf);
-        out_buffer.append(&mut ver_str_buf);
+        out_buffer.append(&mut data_id_buf);
+        out_buffer.append(&mut net_protocol_version_buf);
         out_buffer.append(&mut name_str_len_buf);
         out_buffer.append(&mut name_str_buf);
 
@@ -848,23 +871,10 @@ impl UserTcpService {
                 return ConnectResult::SleepWithErr(PASSWORD_RETRY_DELAY_SEC);
             }
             Some(ConnectServerAnswer::WrongVersion) => {
-                // Get correct version string (get size first).
-                loop {
-                    match self.read_from_socket(&mut in_buf) {
-                        IoResult::WouldBlock => {
-                            thread::sleep(Duration::from_millis(INTERVAL_TCP_MESSAGE_MS));
-                            continue;
-                        }
-                        IoResult::Ok(_bytes) => break,
-                        res => return ConnectResult::IoErr(res),
-                    }
-                }
-                let required_ver_str_size = u16::decode::<u16>(&in_buf).unwrap();
-
-                // Get correct version string.
-                let mut required_ver_str_buf = vec![0u8; required_ver_str_size as usize];
+                // Get correct version.
+                let mut required_ver_buf = vec![0u8; std::mem::size_of::<u64>()];
                 loop {
-                    match self.read_from_socket(&mut required_ver_str_buf) {
+                    match self.read_from_socket(&mut required_ver_buf) {
                         IoResult::WouldBlock => {
                             thread::sleep(Duration::from_millis(INTERVAL_TCP_MESSAGE_MS));
                             continue;
@@ -873,15 +883,13 @@ impl UserTcpService {
                         res => return ConnectResult::IoErr(res),
                     }
                 }
-                let ver_str = std::str::from_utf8(&required_ver_str_buf);
+                let ver_str = u64::decode::<u64>(&required_ver_buf);
                 if let Err(e) = ver_str {
                     return ConnectResult::Err(
-                        format!("std::str::from_utf8() failed, error: failed to convert on 'required_ver_str_buf' (error: {}) at [{}, {}]",
+                        format!("u64::decode::<u64>() failed, error: failed to convert on 'required_ver_str_buf' (error: {}) at [{}, {}]",
                         e, file!(), line!()));
                 }
-                return ConnectResult::WrongVersion(
-                    String::from(std::str::from_utf8(&required_ver_str_buf).unwrap()).clone(),
-                );
+                return ConnectResult::WrongProtocol(ver_str.unwrap());
             }
             Some(ConnectServerAnswer::UsernameTaken) => return ConnectResult::UsernameTaken,
             None => {