301 Days (redux)

Another metric leap year of gamedev experiments and such

Day 68 - Protocol

Jul 22, 2016 - 3 minute read - OldDaysseitan-spin

I wasn’t sure you’d get a Goldie Hahn reference.

In which we learn the binary language of moisture vaporators.

Note: Due to a bit of a situation at work, I’m suddenly very busy again. Rather than lose what little momentum exists, I’ll be doing shorter posts.

Test Every Day

CLIENT_VERSION

Let’s keep striking away at that config file. One we skipped earlier is the CLIENT_VERSION. It appears to be used in only one place, where it is simply communicated to the client along with the APP_VERSION:

DragonsSpine/GameSystems/Network/Protocol.cs GitLab 
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public static void sendWorldVersion(Character ch)
{
    try
    {
        string message = Protocol.VERSION_SERVER + DragonsSpineMain.APP_VERSION + Protocol.VERSION_SERVER_END;
        message += Protocol.VERSION_CLIENT + DragonsSpineMain.CLIENT_VERSION + Protocol.VERSION_CLIENT_END;
        ch.Write(message);
    }

As might be clear, this is using a custom protocol rather than simple ANSI. So we’ll need to figure out how to connect using this protocol (you can see why I initially skipped this part). sendWorldVersion is called by PrintMainMenu if the character’s protocol is equal to APP_PROTOCOL (also from the config file, and defaulted to “Kesmai” in the original code repo).

So how is the character’s protocol determined? It defaults to “normal” and can be swapped between “normal” and “old-kesmai” at the menu, that’s easy enough to find. But the only place I see it being set to anything else is in Protocol.CheckMenuCommand:

DragonsSpine/GameSystems/Network/Protocol.cs GitLab 
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            #region Set Protocol
            if (command == SET_PROTOCOL)
            {
                ch.protocol = DragonsSpineMain.APP_PROTOCOL;
                Menu.PrintMainMenu(ch);
                return true;
            }
            #endregion

Earlier on, we see SET_PROTOCOL = (char)27 + "98" + (char)27, so it seems that this particular escape sequence being sent at any menu will do the trick. I’ll assume that a custom client application just knows to do this itself.

features/config_file.feature GitLab 
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Scenario: CLIENT_VERSION sent at main menu
    Given I use the "minimal" database as-is
    And I set "CLIENT_VERSION" in the config file to "25.6.2.4"
    And the server is started
    When I log on using a standard account
    And I send the protocol command "SET_PROTOCOL"
    Then I receive a CLIENT_VERSION of "25.6.2.4"
features/lib/protocol.rb GitLab 
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PROTOCOL_STRINGS = {
    SET_PROTOCOL: "\e98\e",
    VERSION_CLIENT: "\eV2\e",
    VERSION_CLIENT_END: "\eV3\e"
}

When(/^I send the protocol command "([^"]*)"$/) do |command|
  resp = telnet_command(@connection, PROTOCOL_STRINGS[command.to_sym], /.../)
end

Then(/^I receive a CLIENT_VERSION of "([^"]*)"$/) do |version|
  expectation = PROTOCOL_STRINGS[:VERSION_CLIENT] +
                version +
                PROTOCOL_STRINGS[:VERSION_CLIENT_END]
  expect(@last_resp).to include(expectation)
end
37 scenarios (37 passed)
278 steps (278 passed)
6m58.251s

TODO/Refactor Every Other Day

features/config_file.feature GitLab 
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# TODO: News message included in protocol WorldInformation.

There’s kind of an obvious one, since we just figured out how to trigger the WorldInformation block.

features/config_file.feature GitLab 
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Scenario: NEWS included in WorldInformation
    Given I use the "minimal" database as-is
    And I set "NEWS" in the config file to "This is a test, do not be alarmed."
    And the server is started
    When I log on using a standard account
    And I send the protocol command "SET_PROTOCOL"
    Then I receive a NEWS of "This is a test, do not be alarmed."
features/lib/protocol.rb GitLab 
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PROTOCOL_STRINGS = {
    SET_PROTOCOL: "\e98\e",
    VERSION_CLIENT: "\eV2\e",
    VERSION_CLIENT_END: "\eV3\e",
    NEWS: "\eM1\e",
    NEWS_END: "\eM2\e"
}
features/lib/protocol.rb GitLab 
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Then(/^I receive a NEWS of "([^"]*)"$/) do |news|
  expectation = PROTOCOL_STRINGS[:NEWS] +
                news +
                PROTOCOL_STRINGS[:NEWS_END]
  expect(@last_resp).to include(expectation)
end
38 scenarios (38 passed)
284 steps (284 passed)
7m8.792s

More fun to be had with the protocol stuff? Of course. Tomorrow.

Useful Stuff

More to come

Day 68 code - tests