JVMTI Over HTTP

A very small example of how JVMTI agents can be written in Rust.

When attached, this library will spawn a HTTP server, that will return JSON responses for a few URLs.

How it works

To accomplish this, the library:

• Uses bindgen to generate Rust bindings to jvmti.h
• Create the Agent_OnLoad, Agent_OnLoad and Agent_OnLoad
• Does some horrible tricks to use mutable static variables to preserve JavaVM and jvmtiEnv pointers
• Uses more nasty mutable static variables to hold a reference to prevent Rust from dropping the tokio runtime and tiny http server.

Attaching

Launch the JVM with the following argument (for the default port of 8001):

-agentpath:/path/to/library/libjvmti_over_http.so

Or, to specify the port, use the following argument:

-agentpath:/path/to/library/libjvmti_over_http.so=port=<port>

Endpoints

This example currently supports two endpoints:

• /VirtualMachine/Version - this actually returns the JVMTI Version
• /Class/GetLoadedClasses - this returns the signature and generic signature of all loaded classes