Get the protocol version to send from the ping packet

[iceiix]

for https://github.com/iceiix/steven/issues/18

[iceiix]

This basically works, but there is an implementation problem with saving/getting the version - you have to click refresh to connect with the right version, because it is retrieved here:

                // TODO: move getting protocol version out of refresh
                let server_protocol_versions = self.server_protocol_versions;
                backr.add_click_func(move |_, game| {
                    let protocol_version: i32 = *server_protocol_versions.get(&address).unwrap_or(&protocol::SUPPORTED_PROTOCOL);
                    println!("self.server_protocol_versions.get = {:?}", self.server_protocol_versions);
                    game.screen_sys.replace_screen(Box::new(super::connecting::Connecting::new(&address)));
                    game.connect_to(&address, protocol_version);
                    true
                });

trying to fix this, but if I do something like:

                let server_protocol_versions = self.server_protocol_versions;
                backr.add_click_func(move |_, game| {
                    let protocol_version: i32 = *server_protocol_versions.get(&address).unwrap_or(&protocol::SUPPORTED_PROTOCOL);
                    println!("self.server_protocol_versions.get = {:?}", self.server_protocol_versions);
                    game.screen_sys.replace_screen(Box::new(super::connecting::Connecting::new(&address)));
                    game.connect_to(&address, protocol_version);
                    true
                });

then:

error[E0495]: cannot infer an appropriate lifetime due to conflicting requirements
   --> src/screen/server_list.rs:156:38
    |
156 |                   backr.add_click_func(move |_, game| {
    |  ______________________________________^
157 | |                     let protocol_version: i32 = *server_protocol_versions.get(&address).unwrap_or(&protocol::SUPPORTED_PROTOCOL);
158 | |                     println!("self.server_protocol_versions.get = {:?}", self.server_protocol_versions);
159 | |                     game.screen_sys.replace_screen(Box::new(super::connecting::Connecting::new(&address)));
160 | |                     game.connect_to(&address, protocol_version);
161 | |                     true
162 | |                 });
    | |_________________^
    |
note: first, the lifetime cannot outlive the anonymous lifetime #1 defined on the method body at 104:5...
   --> src/screen/server_list.rs:104:5
    |
104 | /     fn reload_server_list(&mut self,
105 | |                           renderer: &mut render::Renderer,
106 | |                           ui_container: &mut ui::Container) {
107 | |         let elements = self.elements.as_mut().unwrap();
...   |
311 | |         }
312 | |     }
    | |_____^
    = note: ...so that the types are compatible:
            expected &mut screen::server_list::ServerList
               found &mut screen::server_list::ServerList
    = note: but, the lifetime must be valid for the static lifetime...
note: ...so that the type `[closure@src/screen/server_list.rs:156:38: 162:18 server_protocol_versions:std::collections::HashMap<std::string::String, i32>, address:std::string::String, self:&mut screen::server_list::ServerList]` will meet its required lifetime bounds
   --> src/screen/server_list.rs:156:23
    |
156 |                 backr.add_click_func(move |_, game| {
    |                       ^^^^^^^^^^^^^^

error: aborting due to previous error

For more information about this error, try `rustc --explain E0495`.

need to find out how/where to save/load the server to protocol version map, so it can be used on connect.

[iceiix]

Some good news: 1.11 is similar enough to 1.10.2 that this change allows Steven to at least connect to both server versions, even without changing the packets (#19 - though not all packets may be processed correctly)

[iceiix]

Forcing a server list refresh works, but isn't a good solution because it breaks the server status text, stuck on "Connecting...": - even though connecting works:

[iceiix]

The server list is loaded from disk (servers.json), not memory, so the problem arises where to get the ping version from, since the closure is passed to .add_click_func(move |_, game| { when initializing the server list. The server connection is initiated in game.connect_to(&address), so maybe that function could retrieve the version, stashed in the Game object, but can tick() access the game object?

[iceiix]

Serializing to disk for now (server_versions.json), although not necessarily ideal, this matches the pattern used by src/screen/edit_server.rs (writes to servers.json) and src/screen/server_list.rs (reads servers.json). This also reduces the likelihood that the user will attempt to connect to a server before receiving the ping response, since it is persisted between application launches (although it may still be possible albeit unlikely, if this situation occurs a warning is logged).