From 9a97d153e84e2d13927b73411902323949ff7c63 Mon Sep 17 00:00:00 2001
From: AJ ONeal <coolaj86@gmail.com>
Date: Wed, 20 May 2020 01:49:40 -0600
Subject: [PATCH] WIP: designing server/listener interfaces

---
 mplexer/packer/listener_test.go | 245 ++++++++++++++++++++++++++++++++
 1 file changed, 245 insertions(+)
 create mode 100644 mplexer/packer/listener_test.go

diff --git a/mplexer/packer/listener_test.go b/mplexer/packer/listener_test.go
new file mode 100644
index 0000000..03f9739
--- /dev/null
+++ b/mplexer/packer/listener_test.go
@@ -0,0 +1,245 @@
+package packer
+
+import (
+	"context"
+	"errors"
+	"fmt"
+	"io"
+	"net"
+	"net/http"
+	"os"
+	"testing"
+	"time"
+
+	"github.com/gorilla/websocket"
+)
+
+func TestDialServer(t *testing.T) {
+
+	// TODO replace the websocket connection with a mock server
+
+	relay := os.Getenv("RELAY")
+	authz := os.Getenv("SECRET")
+
+	ctx := context.Background()
+	wsd := websocket.Dialer{}
+	headers := http.Header{}
+	headers.Set("Authorization", fmt.Sprintf("Bearer %s", authz))
+	// *http.Response
+	wsconn, _, err := wsd.DialContext(ctx, relay, headers)
+	if nil != err {
+		t.Fatal(err)
+		return
+	}
+
+	mux := &MyMux{}
+	err = ListenAndServe(wsconn, mux)
+	t.Fatal(err)
+}
+
+type Listener struct {
+	ws       *websocket.Conn
+	incoming chan *Conn
+	close    chan struct{}
+}
+
+func ListenAndServe(ws *websocket.Conn, mux Mux) error {
+	listener := Listen(ws)
+	return Serve(listener, mux)
+}
+
+func Listen(ws *websocket.Conn) *Listener {
+	listener := &Listener{
+		ws:       ws,
+		incoming: make(chan *Conn, 1),
+		close:    make(chan struct{}),
+	}
+
+	ctx := context.TODO()
+	r := &WSConn{
+		c: ws,
+		r: nil,
+		w: nil,
+	}
+	decoder := NewDecoder(ctx, r)
+
+	// Feed websocket into Decoder
+	th := &testHandler2{
+		conns:  map[string]*Conn{},
+		connCh: listener.incoming,
+	}
+	go func() {
+		// TODO pass error to Accept()
+		err := decoder.StreamDecode(th, 0)
+		fmt.Printf("the main stream is done: %q", err)
+	}()
+
+	return listener
+}
+
+type testHandler2 struct {
+	conns        map[string]*Conn
+	connCh       chan *Conn
+	chunksParsed int
+	bytesRead    int
+}
+
+func (th *testHandler2) WriteMessage(a Addr, b []byte) {
+	th.chunksParsed++
+	addr := &a
+	_, ok := th.conns[addr.Network()]
+	if !ok {
+		rconn, wconn := net.Pipe()
+		conn := &Conn{
+			updated:         time.Now(),
+			relayRemoteAddr: *addr,
+			relay:           rconn,
+			local:           wconn,
+		}
+		th.conns[addr.Network()] = conn
+		th.connCh <- conn
+	}
+	th.bytesRead += len(b)
+}
+
+func Serve(listener *Listener, mux Mux) error {
+	w := &WSConn{
+		c: listener.ws,
+		r: nil,
+		w: nil,
+	}
+	ctx := context.TODO()
+	encoder := NewEncoder(ctx, w)
+	encoder.Start()
+
+	for {
+		client, err := listener.Accept()
+		if nil != err {
+			return err
+		}
+		lconn, err := mux.LookupTarget(client.LocalAddr())
+		if nil != err {
+			conn.Close()
+			continue
+		}
+
+		go func() {
+			// TODO handle err
+			err := encoder.StreamEncode(*conn.LocalAddr(), lconn, 0)
+			fmt.Printf("a stream is done: %q", err)
+		}()
+	}
+}
+
+func Blah() {
+		go func() {
+			pipe
+		}
+
+
+}
+
+func (l *Listener) Accept() (*Conn, error) {
+	select {
+	case conn, ok := <-l.incoming:
+		if ok {
+			return conn, nil
+		}
+		return nil, io.EOF
+
+	case <-l.close:
+		l.ws.Close()
+		// TODO is another error more suitable?
+		return nil, http.ErrServerClosed
+	}
+}
+
+type Mux interface {
+	LookupTarget(*Addr) (net.Conn, error)
+}
+
+type MyMux struct {
+}
+
+// this function is very client-specific logic
+func (m *MyMux) LookupTarget(paddr *Addr) (net.Conn, error) {
+	//if target := LookupPort(paddr.Port()); nil != target { }
+	if target := m.LookupServername(paddr.Hostname()); nil != target {
+		tconn, err := net.Dial(target.Network(), target.Hostname())
+		if nil != err {
+			return nil, err
+		}
+		/*
+			// TODO for http proxy
+			return mplexer.TargetOptions {
+				Hostname // default localhost
+				Termination // default TLS
+				XFWD // default... no?
+				Port // default 0
+				Conn // should be dialed beforehand
+			}, nil
+		*/
+		return tconn, nil
+	}
+	// TODO
+	return nil, errors.New("Bad Gateway")
+}
+
+func (m *MyMux) LookupServername(servername string) *Addr {
+	return NewAddr(
+		HTTPS,
+		TCP, // TCP -> termination.None? / Plain?
+		"localhost",
+		3000,
+	)
+}
+
+type WSConn struct {
+	c      *websocket.Conn
+	r      io.Reader
+	w      io.WriteCloser
+	pingCh chan struct{}
+}
+
+func (ws *WSConn) Read(b []byte) (int, error) {
+	if nil == ws.r {
+		_, r, err := ws.c.NextReader()
+		if nil != err {
+			return 0, err
+		}
+		ws.r = r
+	}
+	n, err := ws.r.Read(b)
+	if io.EOF == err {
+		err = nil
+	}
+	return n, err
+}
+
+func (ws *WSConn) Write(b []byte) (int, error) {
+	// TODO create or reset ping deadline
+
+	w, err := ws.c.NextWriter(websocket.BinaryMessage)
+	if nil != err {
+		return 0, err
+	}
+	ws.w = w
+	n, err := ws.w.Write(b)
+	if nil != err {
+		return n, err
+	}
+	err = ws.w.Close()
+	return n, err
+}
+
+func (ws *WSConn) Close() error {
+	// TODO handle EOF as websocket.CloseNormal?
+	message := websocket.FormatCloseMessage(websocket.CloseGoingAway, "closing connection")
+	deadline := time.Now().Add(10 * time.Second)
+	err := ws.c.WriteControl(websocket.CloseMessage, message, deadline)
+	if nil != err {
+		fmt.Fprintf(os.Stderr, "failed to write close message to websocket: %s\n", err)
+	}
+	_ = ws.c.Close()
+	return err
+}