Add CONTRIBUTING guide, detailing packet capture and updating to latest patch

CONTRIBUTING.md

@@ -0,0 +1,27 @@
+# Contributing and working on Kawari
+
+Here are various helpful resources and tips when working on Kawari.
+
+## Packet capture
+
+The well-tested packet capturing solutions are [TemporalStasis](https://github.com/WorkingRobot/TemporalStasis/) and [Project Chronofoil](https://github.com/ProjectChronofoil). You should use Project Chronofoil under most circumstances, but it requires Dalamud. TemporalStasis works like a standalone proxy server, and can work with a vanilla game.
+
+To extract `.cfcap` captures from Project Chronofoil, use `cfcap-expand` from [XIVPacketTools](https://github.com/redstrate/XIVPacketTools).
+
+## Updating to new patches
+
+Here are the various things that should be checked when updating Kawari to a newer patch:
+
+* Bump the supported game versions in `lib.rs` so the patch server lets you through.
+* Double check IPC struct sizes in `calc_size()` if the structures changed.
+* Replace testing data in `resources/tests` and re-run the tests.
+* The IPC opcodes _will_ change and must all be replaced.
+* Check the game version used in the encryption key in `lib.rs`.
+
+## Contributing
+
+Before making a pull request, make sure:
+
+* Kawari compiles and runs fine. At a minimum, you should be able to login to the World server.
+* Run `cargo fmt` to ensure your code is formatted.
+* Run `cargo clippy` and fix all of the warnings for any new code, to the best of your ability.

README.md

@@ -18,7 +18,11 @@ Only the Global region is supported. Only the Windows client is supported. Suppo
 
 ## Running
 
-A guide to running Kawari can be followed [here](USAGE.md).
+Kawari is designed to be easy to run. A guide to running Kawari can be followed [here](USAGE.md).
+
+## Contributing
+
+Pull requests for new features, patch updates, and documentation are welcome. A guide for contributing and updating Kawari can be found [here](CONTRIBUTING.md).
 
 ## Credits & Thank You
 

src/lib.rs

@@ -32,6 +32,9 @@ pub mod login;
 /// Patch server-specific code.
 pub mod patch;
 
+/// Used in the encryption key.
+const GAME_VERSION: u16 = 7000;
+
 /// Supported boot version.
 pub const SUPPORTED_BOOT_VERSION: Version = Version("2025.01.10.0000.0001");
 

src/packet/encryption.rs

@@ -2,12 +2,10 @@ use std::io::Cursor;
 
 use binrw::BinResult;
 
-use crate::blowfish::Blowfish;
+use crate::{GAME_VERSION, blowfish::Blowfish};
 
 use super::ReadWriteIpcSegment;
 
-const GAME_VERSION: u16 = 7000;
-
 pub fn generate_encryption_key(key: &[u8], phrase: &str) -> [u8; 16] {
     let mut base_key = vec![0x78, 0x56, 0x34, 0x12];
     base_key.extend_from_slice(key);