TUN-3617: Separate service from client, and implement different client for http vs. tcp origins

- extracted ResponseWriter from proxyConnection
 - added bastion tests over websocket
 - removed HTTPResp()
 - added some docstrings
 - Renamed some ingress clients as proxies
 - renamed instances of client to proxy in connection and origin
 - Stream no longer takes a context and logger.Service

ingress/origin_connection.go

@@ -0,0 +1,62 @@
+package ingress
+
+import (
+	"io"
+	"net"
+	"net/http"
+
+	"github.com/cloudflare/cloudflared/websocket"
+	gws "github.com/gorilla/websocket"
+)
+
+// OriginConnection is a way to stream to a service running on the user's origin.
+// Different concrete implementations will stream different protocols as long as they are io.ReadWriters.
+type OriginConnection interface {
+	// Stream should generally be implemented as a bidirectional io.Copy.
+	Stream(tunnelConn io.ReadWriter)
+	Close()
+}
+
+// tcpConnection is an OriginConnection that directly streams to raw TCP.
+type tcpConnection struct {
+	conn          net.Conn
+	streamHandler func(tunnelConn io.ReadWriter, originConn net.Conn)
+}
+
+func (tc *tcpConnection) Stream(tunnelConn io.ReadWriter) {
+	tc.streamHandler(tunnelConn, tc.conn)
+}
+
+func (tc *tcpConnection) Close() {
+	tc.conn.Close()
+}
+
+// wsConnection is an OriginConnection that streams to TCP packets by encapsulating them in Websockets.
+// TODO: TUN-3710 Remove wsConnection and have helloworld service reuse tcpConnection like bridgeService does.
+type wsConnection struct {
+	wsConn *gws.Conn
+	resp   *http.Response
+}
+
+func (wsc *wsConnection) Stream(tunnelConn io.ReadWriter) {
+	websocket.Stream(tunnelConn, wsc.wsConn.UnderlyingConn())
+}
+
+func (wsc *wsConnection) Close() {
+	wsc.resp.Body.Close()
+	wsc.wsConn.Close()
+}
+
+func newWSConnection(transport *http.Transport, r *http.Request) (OriginConnection, error) {
+	d := &gws.Dialer{
+		TLSClientConfig: transport.TLSClientConfig,
+	}
+	wsConn, resp, err := websocket.ClientConnect(r, d)
+	if err != nil {
+		return nil, err
+	}
+	return &wsConnection{
+		wsConn,
+		resp,
+	}, nil
+}