cloudflared-mirror/carrier/carrier.go

217 lines
6.1 KiB
Go

//Package carrier provides a WebSocket proxy to carry or proxy a connection
//from the local client to the edge. See it as a wrapper around any protocol
//that it packages up in a WebSocket connection to the edge.
package carrier
import (
"io"
"net"
"net/http"
"os"
"strings"
"github.com/cloudflare/cloudflared/cmd/cloudflared/token"
cloudflaredWebsocket "github.com/cloudflare/cloudflared/websocket"
"github.com/gorilla/websocket"
"github.com/sirupsen/logrus"
)
type StartOptions struct {
OriginURL string
Headers http.Header
}
// StdinoutStream is empty struct for wrapping stdin/stdout
// into a single ReadWriter
type StdinoutStream struct {
}
// Read will read from Stdin
func (c *StdinoutStream) Read(p []byte) (int, error) {
return os.Stdin.Read(p)
}
// Write will write to Stdout
func (c *StdinoutStream) Write(p []byte) (int, error) {
return os.Stdout.Write(p)
}
// Helper to allow defering the response close with a check that the resp is not nil
func closeRespBody(resp *http.Response) {
if resp != nil {
resp.Body.Close()
}
}
// StartClient will copy the data from stdin/stdout over a WebSocket connection
// to the edge (originURL)
func StartClient(logger *logrus.Logger, stream io.ReadWriter, options *StartOptions) error {
return serveStream(logger, stream, options)
}
// StartServer will setup a listener on a specified address/port and then
// forward connections to the origin by calling `Serve()`.
func StartServer(logger *logrus.Logger, address string, shutdownC <-chan struct{}, options *StartOptions) error {
listener, err := net.Listen("tcp", address)
if err != nil {
logger.WithError(err).Error("failed to start forwarding server")
return err
}
logger.Info("Started listening on ", address)
return Serve(logger, listener, shutdownC, options)
}
// Serve accepts incoming connections on the specified net.Listener.
// Each connection is handled in a new goroutine: its data is copied over a
// WebSocket connection to the edge (originURL).
// `Serve` always closes `listener`.
func Serve(logger *logrus.Logger, listener net.Listener, shutdownC <-chan struct{}, options *StartOptions) error {
defer listener.Close()
for {
select {
case <-shutdownC:
return nil
default:
conn, err := listener.Accept()
if err != nil {
return err
}
go serveConnection(logger, conn, options)
}
}
}
// serveConnection handles connections for the Serve() call
func serveConnection(logger *logrus.Logger, c net.Conn, options *StartOptions) {
defer c.Close()
serveStream(logger, c, options)
}
// serveStream will serve the data over the WebSocket stream
func serveStream(logger *logrus.Logger, conn io.ReadWriter, options *StartOptions) error {
wsConn, err := createWebsocketStream(options)
if err != nil {
logger.WithError(err).Errorf("failed to connect to %s\n", options.OriginURL)
return err
}
defer wsConn.Close()
cloudflaredWebsocket.Stream(wsConn, conn)
return nil
}
// createWebsocketStream will create a WebSocket connection to stream data over
// It also handles redirects from Access and will present that flow if
// the token is not present on the request
func createWebsocketStream(options *StartOptions) (*cloudflaredWebsocket.Conn, error) {
req, err := http.NewRequest(http.MethodGet, options.OriginURL, nil)
if err != nil {
return nil, err
}
req.Header = options.Headers
wsConn, resp, err := cloudflaredWebsocket.ClientConnect(req, nil)
defer closeRespBody(resp)
if err != nil && IsAccessResponse(resp) {
wsConn, err = createAccessAuthenticatedStream(options)
if err != nil {
return nil, err
}
} else if err != nil {
return nil, err
}
return &cloudflaredWebsocket.Conn{Conn: wsConn}, nil
}
// IsAccessResponse checks the http Response to see if the url location
// contains the Access structure.
func IsAccessResponse(resp *http.Response) bool {
if resp == nil || resp.StatusCode != http.StatusFound {
return false
}
location, err := resp.Location()
if err != nil || location == nil {
return false
}
if strings.HasPrefix(location.Path, "/cdn-cgi/access/login") {
return true
}
return false
}
// createAccessAuthenticatedStream will try load a token from storage and make
// a connection with the token set on the request. If it still get redirect,
// this probably means the token in storage is invalid (expired/revoked). If that
// happens it deletes the token and runs the connection again, so the user can
// login again and generate a new one.
func createAccessAuthenticatedStream(options *StartOptions) (*websocket.Conn, error) {
wsConn, resp, err := createAccessWebSocketStream(options)
defer closeRespBody(resp)
if err == nil {
return wsConn, nil
}
if !IsAccessResponse(resp) {
return nil, err
}
// Access Token is invalid for some reason. Go through regen flow
originReq, err := http.NewRequest(http.MethodGet, options.OriginURL, nil)
if err != nil {
return nil, err
}
if err := token.RemoveTokenIfExists(originReq.URL); err != nil {
return nil, err
}
wsConn, resp, err = createAccessWebSocketStream(options)
defer closeRespBody(resp)
if err != nil {
return nil, err
}
return wsConn, nil
}
// createAccessWebSocketStream builds an Access request and makes a connection
func createAccessWebSocketStream(options *StartOptions) (*websocket.Conn, *http.Response, error) {
req, err := BuildAccessRequest(options)
if err != nil {
return nil, nil, err
}
return cloudflaredWebsocket.ClientConnect(req, nil)
}
// buildAccessRequest builds an HTTP request with the Access token set
func BuildAccessRequest(options *StartOptions) (*http.Request, error) {
req, err := http.NewRequest(http.MethodGet, options.OriginURL, nil)
if err != nil {
return nil, err
}
token, err := token.FetchToken(req.URL)
if err != nil {
return nil, err
}
// We need to create a new request as FetchToken will modify req (boo mutable)
// as it has to follow redirect on the API and such, so here we init a new one
originRequest, err := http.NewRequest(http.MethodGet, options.OriginURL, nil)
if err != nil {
return nil, err
}
originRequest.Header.Set("cf-access-token", token)
for k, v := range options.Headers {
if len(v) >= 1 {
originRequest.Header.Set(k, v[0])
}
}
return originRequest, nil
}