cloudflared-mirror/carrier/carrier.go

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//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 (
"errors"
"io"
"net"
"net/http"
"os"
"strings"
"github.com/cloudflare/cloudflared/cmd/cloudflared/token"
"github.com/cloudflare/cloudflared/websocket"
"github.com/sirupsen/logrus"
)
// 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)
}
// StartClient will copy the data from stdin/stdout over a WebSocket connection
// to the edge (originURL)
func StartClient(logger *logrus.Logger, originURL string, stream io.ReadWriter) error {
return serveStream(logger, originURL, stream)
}
// StartServer will setup a server on a specified port and copy data over a WebSocket connection
// to the edge (originURL)
func StartServer(logger *logrus.Logger, address, originURL string, shutdownC <-chan struct{}) error {
listener, err := net.Listen("tcp", address)
if err != nil {
logger.WithError(err).Error("failed to start forwarding server")
return err
}
defer listener.Close()
for {
select {
case <-shutdownC:
return nil
default:
conn, err := listener.Accept()
if err != nil {
return err
}
go serveConnection(logger, conn, originURL)
}
}
}
// serveConnection handles connections for the StartServer call
func serveConnection(logger *logrus.Logger, c net.Conn, originURL string) {
defer c.Close()
serveStream(logger, originURL, c)
}
// serveStream will serve the data over the WebSocket stream
func serveStream(logger *logrus.Logger, originURL string, conn io.ReadWriter) error {
wsConn, err := createWebsocketStream(originURL)
if err != nil {
logger.WithError(err).Error("failed to create websocket stream")
return err
}
defer wsConn.Close()
websocket.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(originURL string) (*websocket.Conn, error) {
req, err := http.NewRequest(http.MethodGet, originURL, nil)
if err != nil {
return nil, err
}
wsConn, resp, err := websocket.ClientConnect(req, nil)
if err != nil && resp != nil && resp.StatusCode > 300 {
location, err := resp.Location()
if err != nil {
return nil, err
}
if !strings.Contains(location.String(), "cdn-cgi/access/login") {
return nil, errors.New("not an Access redirect")
}
req, err := buildAccessRequest(originURL)
if err != nil {
return nil, err
}
wsConn, _, err = websocket.ClientConnect(req, nil)
if err != nil {
return nil, err
}
} else if err != nil {
return nil, err
}
return &websocket.Conn{Conn: wsConn}, nil
}
// buildAccessRequest builds an HTTP request with the Access token set
func buildAccessRequest(originURL string) (*http.Request, error) {
req, err := http.NewRequest(http.MethodGet, 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, originURL, nil)
if err != nil {
return nil, err
}
originRequest.Header.Set("cf-access-token", token)
return originRequest, nil
}