94 lines
2.8 KiB
Go
94 lines
2.8 KiB
Go
// Copyright 2024 New Vector Ltd.
|
|
// Copyright 2020 The Matrix.org Foundation C.I.C.
|
|
//
|
|
// SPDX-License-Identifier: AGPL-3.0-only
|
|
// Please see LICENSE in the repository root for full details.
|
|
|
|
//go:build wasm
|
|
// +build wasm
|
|
|
|
package main
|
|
|
|
import (
|
|
"bufio"
|
|
"fmt"
|
|
"net/http"
|
|
"net/http/httptest"
|
|
"strings"
|
|
"syscall/js"
|
|
)
|
|
|
|
// JSServer exposes an HTTP-like server interface which allows JS to 'send' requests to it.
|
|
type JSServer struct {
|
|
// The router which will service requests
|
|
Mux http.Handler
|
|
}
|
|
|
|
// OnRequestFromJS is the function that JS will invoke when there is a new request.
|
|
// The JS function signature is:
|
|
// function(reqString: string): Promise<{result: string, error: string}>
|
|
// Usage is like:
|
|
// const res = await global._go_js_server.fetch(reqString);
|
|
// if (res.error) {
|
|
// // handle error: this is a 'network' error, not a non-2xx error.
|
|
// }
|
|
// const rawHttpResponse = res.result;
|
|
func (h *JSServer) OnRequestFromJS(this js.Value, args []js.Value) interface{} {
|
|
// we HAVE to spawn a new goroutine and return immediately or else Go will deadlock
|
|
// if this request blocks at all e.g for /sync calls
|
|
httpStr := args[0].String()
|
|
promise := js.Global().Get("Promise").New(js.FuncOf(func(pthis js.Value, pargs []js.Value) interface{} {
|
|
// The initial callback code for new Promise() is also called on the critical path, which is why
|
|
// we need to put this in an immediately invoked goroutine.
|
|
go func() {
|
|
resolve := pargs[0]
|
|
resStr, err := h.handle(httpStr)
|
|
errStr := ""
|
|
if err != nil {
|
|
errStr = err.Error()
|
|
}
|
|
resolve.Invoke(map[string]interface{}{
|
|
"result": resStr,
|
|
"error": errStr,
|
|
})
|
|
}()
|
|
return nil
|
|
}))
|
|
return promise
|
|
}
|
|
|
|
// handle invokes the http.ServeMux for this request and returns the raw HTTP response.
|
|
func (h *JSServer) handle(httpStr string) (resStr string, err error) {
|
|
req, err := http.ReadRequest(bufio.NewReader(strings.NewReader(httpStr)))
|
|
if err != nil {
|
|
return
|
|
}
|
|
w := httptest.NewRecorder()
|
|
|
|
h.Mux.ServeHTTP(w, req)
|
|
|
|
res := w.Result()
|
|
var resBuffer strings.Builder
|
|
err = res.Write(&resBuffer)
|
|
return resBuffer.String(), err
|
|
}
|
|
|
|
// ListenAndServe registers a variable in JS-land with the given namespace. This variable is
|
|
// a function which JS-land can call to 'send' HTTP requests. The function is attached to
|
|
// a global object called "_go_js_server". See OnRequestFromJS for more info.
|
|
func (h *JSServer) ListenAndServe(namespace string) {
|
|
globalName := "_go_js_server"
|
|
// register a hook in JS-land for it to invoke stuff
|
|
server := js.Global().Get(globalName)
|
|
if !server.Truthy() {
|
|
server = js.Global().Get("Object").New()
|
|
js.Global().Set(globalName, server)
|
|
}
|
|
|
|
server.Set(namespace, js.FuncOf(h.OnRequestFromJS))
|
|
|
|
fmt.Printf("Listening for requests from JS on function %s.%s\n", globalName, namespace)
|
|
// Block forever to mimic http.ListenAndServe
|
|
select {}
|
|
}
|