WIP: add gRPC sample

[bacongobbler]

Does not work; using this as a test bed for upstream changes in wasi-http.

[bacongobbler]

Steps to get this sample working:

1. Compile the .NET runtime off [NativeAOT-LLVM] support System.Net.Http.HttpClient on WASIp2 dotnet/runtimelab#2614, with one additional change to force incoming responses to respond as HTTP/2 (necessary because the incoming response handler currently downgrades the response to HTTP/1.1):

diff --git a/src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpHandler.cs b/src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpHandler.cs
index 1e5dc53e02c..8e8e78bfb5b 100644
--- a/src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpHandler.cs
+++ b/src/libraries/System.Net.Http/src/System/Net/Http/WasiHttpHandler/WasiHttpHandler.cs
@@ -58,6 +58,22 @@ public async Task<HttpResponseMessage> SendRequestAsync(HttpRequestMessage reque

                 var response = new HttpResponseMessage((HttpStatusCode)incomingResponse.Status());

+                // Force inbound response to use HTTP/2 if TE=trailers is set
+                //
+                // No System.Linq support =(
+                IEnumerable<string>? values = null;
+                if (request.Headers.TryGetValues("TE", out values))
+                {
+                    foreach (var value in values)
+                    {
+                        if (value == "trailers")
+                        {
+                            response.Version = HttpVersion.Version20;
+                            break;
+                        }
+                    }
+                }
+
                 // request body could be still streaming after response headers are received and started streaming response
                 // we will leave scope of this method
                 // we need to pass the ownership of the request and this wrapper to the response (via response content stream)

You'll also want to compile LLVM and the latest version of the wasi-sdk:

https://github.com/llvm/llvm-project/releases/tag/llvmorg-18.1.8
https://github.com/WebAssembly/wasi-sdk/releases/tag/wasi-sdk-24

Rough steps to compile runtimelab:

git clone [email protected]:dicej/runtimelab
cd runtimelab
git checkout system-net-http-wasi
export WASI_SDK_PATH=/tmp/wasi-sdk-24.0-x86_64-linux
export LLVM_CMAKE_CONFIG=/tmp/llvm-project/build
./build.sh clr.aot+libs -c Release -a wasm -os wasi
./build.sh clr.wasmjit+clr.aot+libs -c Release
./build.sh nativeaot.packages -c Release
./build.sh nativeaot.packages -a wasm -os wasi -c Release -rf CoreCLR

2. Use @dicej's grpc-hacks branch for wasmtime:

git clone [email protected]:dicej/wasmtime
cd wasmtime
git checkout grpc-hacks
cargo install .

Use GrpcGreeter as the server:

git clone [email protected]:bacongobbler/GrpcGreeter
cd GrpcGreeter
dotnet run

Then in another terminal, build and run the sample:

cd samples/http-grpc
spin build
wasmtime serve -S cli --addr 0.0.0.0:3000 build/App.wasm

Then issue a request.

><> curl localhost:3000
Hello, gRPC!