poc for wasm plugin in Filestash - to remove

main.go

package main

import (
	"bufio"
	"bytes"
	"context"
	"fmt"
	"io"
	"log"
	"net/http"
	"os"

	"github.com/tetratelabs/wazero"
)

func main() {
	if len(os.Args) != 2 {
		fmt.Printf("Usage: %s <wasm-file>\n", os.Args[0])
		os.Exit(1)
	}
	// init
	wasmFile := os.Args[1]
	wasmBytes, err := os.ReadFile(wasmFile)
	if err != nil {
		log.Fatalf("Failed to read WASM file: %v", err)
	}
	ctx := context.Background()
	runtime := wazero.NewRuntime(ctx)
	defer runtime.Close(ctx)
	compiledModule, err := runtime.CompileModule(ctx, wasmBytes)
	if err != nil {
		log.Fatalf("Failed to compile WASM: %v", err)
	}
	module, err := runtime.InstantiateModule(ctx, compiledModule, wazero.NewModuleConfig())
	if err != nil {
		log.Fatalf("Failed to instantiate WASM: %v", err)
	}
	httpFunc := module.ExportedFunction("http")
	if httpFunc == nil {
		log.Fatalf("WASM module does not export 'http' function")
	}

	// run
	results, err := httpFunc.Call(ctx)
	if err != nil {
		log.Fatalf("Failed to call http function: %v", err)
	} else if len(results) != 1 {
		log.Fatalf("Failed to parse response")
		return
	}

	// output - read null-terminated string
	ptr := uint32(results[0])
	memory := module.Memory()

	var responseLength uint32
	for offset := uint32(0); ; offset += 8192 {
		chunk, ok := memory.Read(ptr+offset, 8192)
		if !ok {
			responseLength = offset
			break
		}
		for i, b := range chunk {
			if b == 0 {
				responseLength = offset + uint32(i)
				goto found
			}
		}
	}
found:
	responseBytes, _ := memory.Read(ptr, responseLength)
	resp, err := http.ReadResponse(bufio.NewReader(bytes.NewReader(responseBytes)), nil)
	defer resp.Body.Close()

	fmt.Printf("- status %d\n", resp.StatusCode)

	for head, value := range resp.Header {
		fmt.Printf("- header %s => %v\n", head, value)
	}
	body, _ := io.ReadAll(resp.Body)
	fmt.Printf("- body %s\n", body)
}

Makefile

.PHONY: all build plugin clean

all: build plugin

build:
	go build -o wasm-http main.go

plugin:
	cargo build --target wasm32-unknown-unknown --release
	cp target/wasm32-unknown-unknown/release/plugin.wasm .

test: all
	./wasm-http plugin.wasm

clean:
	rm -f wasm-http plugin.wasm

plugin.rs

#[no_mangle]
pub extern "C" fn http() -> *const u8 {
    b"HTTP/1.1 200 OK\r\nContent-Type: text/html\r\nContent-Length: 13\r\n\r\nHello, WASM!\0".as_ptr()
}