Multiplayer Code: File Checksum to allow local mission loading

Right now, regardless of whether a client has the server's mission on his local PC, we must still download the mission from the server in its entirety. This makes for some very long waits when some of these missions with voice overs approach 30Mb.

What I propose is a hash check like MD5, where the clients can ping the server to determine the hash of the existing mission, then if it matches the client can load the mission from its own hard drive rather than using the server's bandwidth. This way, people who fly together with large missions can significantly reduce the wait time, and since MIZ missions are essentially Zip files, MD5 hashing is already commonplace for verifying the integrity of downloads.

EDIT:

I thought of some additional features for implementation:

1. The option for allowing MD5 checking should be server-side, so if a server wishes to keep a mission proprietary it can do so.
   
2. Create a cache folder under Saved Games\DCS\Missions (e.g. _MPCache) that stores missions downloaded from servers (H/T shagrat). This allows quick rejoin in the event someone drops from the server. Missions should be directly accessible if people wish to copy to their own mission folder (proprietary missions will not be cached).
   
3. Allow DCS to parse additional folders for existing missions based on entries in autoexec.lua, similar to the entries that allow additional entries into the texture path.
   

Right now, regardless of whether a client has the server's mission on his local PC, we must still download the mission from the server in its entirety. This makes for some very long waits when some of these missions with voice overs approach 30Mb.

 

What I propose is a hash check like MD5, where the clients can ping the server to determine the hash of the existing mission, then if it matches the client can load the mission from its own hard drive rather than using the server's bandwidth. This way, people who fly together with large missions can significantly reduce the wait time, and since MIZ missions are essentially Zip files, MD5 hashing is already commonplace for verifying the integrity of downloads.

This is a fantastic idea!!! +1000

If you set a specific MP mission directory this could be pretty easy.

Even if just the last mission is cached and hash checked it could tremendously cut down on MP join times when you have a server crash, or disconnect etc.

Great idea! I hope they act on this.

Great idea! This should save a lot of time, especially for large missions (dynamic).

Bumped for some additional implementation suggestions in the OP.

ah please come on.

I spend more time loading and reloading after a disconnect or due to timeouts than playing the game :s.