Capnp-go web sockets server

main.go

package main

import (
	"fmt"
	"io"
	"net/http"

	"github.com/gin-gonic/gin"
	"github.com/gorilla/websocket"
	"github.com/spf13/afero"
	"zombiezen.com/go/capnproto2/rpc"
)

const basePath = "."

var fs = afero.NewOsFs()

type wsConnection struct {
	*websocket.Conn
	reader io.Reader
}

func (wsc *wsConnection) Read(buffer []byte) (int, error) {
	if wsc.reader == nil {
		_, r, err := wsc.Conn.NextReader()
		if err != nil {
			return 0, err
		}
		wsc.reader = r
	}
	n, err := wsc.reader.Read(buffer)
	if err == io.EOF {
		// Swallow the EOF and switch to the next reader on the next call.
		err = nil
		wsc.reader = nil
	}
	return n, err
}

func (wsc *wsConnection) Write(buffer []byte) (int, error) {
	w, err := wsc.Conn.NextWriter(websocket.BinaryMessage)
	if err != nil {
		return 0, err
	}
	defer w.Close()
	return w.Write(buffer)
}

var wsupgrader = websocket.Upgrader{
	CheckOrigin: func(r *http.Request) bool {
		return true
	},
}

func wshandler(w http.ResponseWriter, r *http.Request) {
	conn, err := wsupgrader.Upgrade(w, r, nil)
	defer conn.Close()
	if err != nil {
		fmt.Printf("failed to set websocket upgrade: %v\n", err)
		return
	}

	wsc := &wsConnection{Conn: conn}
	t := rpc.StreamTransport(wsc)
	file, err := fs.Open(basePath)
	if err != nil {
		fmt.Printf("failed to open basePath: %v\n", err)
		return
	}
	node := &FSNodeImpl{Fs: fs, Handle: file}
	srv := FSNode_ServerToClient(node)
	rpcConn := rpc.NewConn(t, rpc.MainInterface(srv.Client), rpc.ConnLog(nil))
	err = rpcConn.Wait()
	if err == nil {
	} else if err == rpc.ErrConnClosed {
	} else if _, ok := err.(rpc.Abort); ok {
	} else {
		panic(err)
	}
}

func main() {
	r := gin.Default()

	r.GET("/", func(c *gin.Context) {
		c.String(200, "We got Gin")
	})
	r.GET("/ws", func(c *gin.Context) {
		wshandler(c.Writer, c.Request)
	})

	r.Run()
}