help understanding types in proxy_on_* functions

[nilslice]

In my attempts to get a basic Rust wasm filter running, I found it difficult to see how the C++ examples translated to what the WIP Rust sdk would look like - at the very least to know what are some VM functions I can hook into from Rust. Aside from the functions defined in api/wasm/rust/src/lib.rs, I was able to find the following (and a few more from module env imports) by disassembling both my Rust wasm and the example C++ wasm output.

Is there any reference material where I can get more specific information about how to translate the i32 params into some data I can work with in Rust? I have been able to start the compiled wasm in envoy, and see the logs from these Rust stubs below, but the proxy_on_request_headers call seems to hang with the return value I'm sending back. This is where I've hit a wall.. I'm not sure what the next hook / VM is expecting to get back.

The stubs I've got in Rust:

#[no_mangle]
fn proxy_on_queue_ready(p0: i32, p1: i32) {
    log::info!("rust: `proxy_on_queue_ready` called, params: p0={} p1={}", p0, p1);
}

#[no_mangle]
fn proxy_on_grpc_close(p0: i32, p1: i32, p2: i32) {
    log::info!("rust: `proxy_on_grpc_close` called, params: p0={} p1={} p2={}", p0, p1, p2);
}

#[no_mangle]
fn proxy_on_grpc_receive(p0: i32, p1: i32, p2: i32) {
    log::info!("rust: `proxy_on_grpc_receive` called, params: p0={} p1={} p2={}", p0, p1, p2);
}

#[no_mangle]
fn proxy_on_grpc_receive_trailing_metadata(p0: i32, p1: i32, p2: i32) {
    log::info!(
        "rust: `proxy_on_grpc_receive_trailing_metadata` called, params: p0={} p1={} p2={}",
        p0, p1, p2
    );
}

#[no_mangle]
fn proxy_on_grpc_receive_initial_metadata(p0: i32, p1: i32, p2: i32) {
    log::info!(
        "rust: `proxy_on_grpc_receive_initial_metadata` called, params: p0={} p1={} p2={}",
        p0, p1, p2
    );
}

#[no_mangle]
fn proxy_on_grpc_create_initial_metadata(p0: i32, p1: i32, p2: i32) {
    log::info!(
        "rust: `proxy_on_grpc_create_initial_metadata` called, params: p0={} p1={} p2={}",
        p0, p1, p2
    );
}

#[no_mangle]
fn proxy_on_http_call_response(p0: i32, p1: i32, p2: i32, p3: i32, p4: i32) {
    log::info!(
        "rust: `proxy_on_http_call_response` calledcalled, params: p0={} p1={} p2={} p3={} p4={}",
        p0, p1, p2, p3, p4
    );
}

#[no_mangle]
fn proxy_on_delete(p0: i32) {
    log::info!("rust: `proxy_on_delete` called");
}

#[no_mangle]
fn proxy_on_log(p0: i32) {
    log::info!("rust: `proxy_on_log` called, params: p0={}", p0);
}

#[no_mangle]
fn proxy_on_done(p0: i32) -> i32 {
    log::info!("rust: `proxy_on_done` called, params: p0={}", p0);
    -999
}

#[no_mangle]
fn proxy_on_response_trailers(p0: i32, p1: i32) -> i32 {
    log::info!("rust: `proxy_on_response_trailers` called, params: p0={} p1={}", p0, p1);
    -999
}

#[no_mangle]
fn proxy_on_response_body(p0: i32, p1: i32, p2: i32) -> i32 {
    log::info!("rust: `proxy_on_response_body` called, params: p0={} p1={} p2={}", p0, p1, p2);
    -999
}

#[no_mangle]
fn proxy_on_response_metadata(p0: i32, p1: i32) -> i32 {
    log::info!("rust: `proxy_on_response_metadata` called, params: p0={} p1={}", p0, p1);
    -999
}

#[no_mangle]
fn proxy_on_response_headers(p0: i32, p1: i32) -> i32 {
    log::info!("rust: `proxy_on_response_headers` called, params: p0={} p1={}", p0, p1);
    -999
}

#[no_mangle]
fn proxy_on_request_trailers(p0: i32, p1: i32) -> i32 {
    log::info!("rust: `proxy_on_request_trailers` called, params: p0={} p1={}", p0, p1);
    -999
}

#[no_mangle]
fn proxy_on_request_body(p0: i32, p1: i32, p2: i32) -> i32 {
    log::info!("rust: `proxy_on_request_body` called, params: p0={} p1={} p2={}", p0, p1, p2);
    -999
}

#[no_mangle]
fn proxy_on_request_metadata(p0: i32, p1: i32) -> i32 {
    log::info!("rust: `proxy_on_request_metadata` called, params: p0={} p1={}", p0, p1);
    -999
}

#[no_mangle]
fn proxy_on_request_headers(p0: i32, p1: i32) -> i32 {
    log::info!("rust: `proxy_on_request_headers` called, params: p0={} p1={}", p0, p1);
    -999
}

#[no_mangle]
fn proxy_on_upstream_connection_close(p0: i32, p1: i32) {
    log::info!("rust: `proxy_on_upstream_connection_close` called, params: p0={} p1={}", p0, p1);
}

#[no_mangle]
fn proxy_on_downstream_connection_close(p0: i32, p1: i32) {
    log::info!("rust: `proxy_on_downstream_connection_close` called, params: p0={} p1={}", p0, p1);
}

#[no_mangle]
fn proxy_on_upstream_data(p0: i32, p1: i32, p2: i32) -> i32 {
    log::info!("rust: `proxy_on_upstream_data` called, params: p0={} p1={} p2={}", p0, p1, p2);
    -999
}

#[no_mangle]
fn proxy_on_downstream_data(p0: i32, p1: i32, p2: i32) -> i32 {
    log::info!("rust: `proxy_on_downstream_data` called, params: p0={} p1={} p2={}", p0, p1, p2);
    -999
}

#[no_mangle]
fn proxy_on_new_connection(p0: i32) -> i32 {
    log::info!("rust: `proxy_on_new_connection` called, params: p0={}", p0);
    -999
}

#[no_mangle]
fn proxy_on_create(p0: i32, p1: i32) {
    log::info!("rust: `proxy_on_create` called, params: p0={} p1={}", p0, p1);
}

#[no_mangle]
fn proxy_on_tick(p0: i32) {
    log::info!("rust: `proxy_on_tick` called, params: p0={}", p0);
}

#[no_mangle]
fn proxy_on_configure(p0: i32, p1: i32) -> i32 {
    log::info!("rust: `proxy_on_configure` called, params: p0={} p1={}", p0, p1);
    -999
}

#[no_mangle]
fn proxy_on_start(p0: i32, p1: i32) -> i32 {
    log::info!("rust: `proxy_on_start` called, params: p0={} p1={}", p0, p1);
    -999
}

Any tips/pointers to discovering what the i32 mean would be greatly appreciated!

Btw, if there hasn't yet been a design set for the Rust SDK, i'd be happy to share some ideas. Thanks again for the work thus far.

Edit:
Ok, I see proxy_wasm_api.h & proxy_wasm_externs.h and can make some assumptions... still, any pointers appreciated 👍

[nilslice]

I've made a bit of progress on the Rust side of things, though admittedly only through hacking around. If there is a chance to get a bit of a review or a quick check if this is useful to continue on, I'd appreciate it.

Thanks @PiotrSikora!

[jplevyak]

The spec is under review at proxy-wasm/spec#1
Comments and requests for clarification welcome!