I'm trying to do a check between the client and the server.

The client sends a PacketPlayLoad to the server verify the .jar.

 

However, I'm in trouble, get the client jar directory.

 

More or less like this:

 

File f = new File (Minecraft. getMinecraftDir (), "versions/<version_here >/<version_here>.jar");

 

However, how to know which version performed by the client?

Which profile, is selected to open the client?

 

You don't.

1) 1.7.10 modding is dead, move on

2) You NEVER trust the client.

Yes, I'm going to do that for several versions.

 

In a more recent version (1.10) is that possible? Get the .jar directory of client?

There is no point in what you are trying to do... JAR file of MC can be left unmodified and have correct CheckSum - yet, client can be modified. Forge itself isn't even in JAR, not to mention any other possible mods or coremods.

 

In simpler words: "Verifying JAR" is impossible.

public int getCheckSum() {
    return "0xF239AFB520983D20978C290FC9"; //hax
}