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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 (
"crypto/tls"
"fmt"
"io"
"net"
"net/http"
"net/url"
"os"
"strings"
"github.com/pkg/errors"
"github.com/rs/zerolog"
"github.com/cloudflare/cloudflared/token"
)
const (
LogFieldOriginURL = "originURL"
CFAccessTokenHeader = "Cf-Access-Token"
cfJumpDestinationHeader = "Cf-Access-Jump-Destination"
)
type StartOptions struct {
AppInfo *token.AppInfo
OriginURL string
Headers http.Header
Host string
TLSClientConfig *tls.Config
}
// Connection wraps up all the needed functions to forward over the tunnel
type Connection interface {
// ServeStream is used to forward data from the client to the edge
ServeStream(*StartOptions, io.ReadWriter) error
}
// 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 deferring the response close with a check that the resp is not nil
func closeRespBody(resp *http.Response) {
if resp != nil {
_ = resp.Body.Close()
}
}
// StartForwarder will setup a listener on a specified address/port and then
// forward connections to the origin by calling `Serve()`.
func StartForwarder(conn Connection, address string, shutdownC <-chan struct{}, options *StartOptions) error {
listener, err := net.Listen("tcp", address)
if err != nil {
return errors.Wrap(err, "failed to start forwarding server")
}
return Serve(conn, listener, shutdownC, options)
}
// StartClient will copy the data from stdin/stdout over a WebSocket connection
// to the edge (originURL)
func StartClient(conn Connection, stream io.ReadWriter, options *StartOptions) error {
return conn.ServeStream(options, stream)
}
// 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(remoteConn Connection, listener net.Listener, shutdownC <-chan struct{}, options *StartOptions) error {
defer listener.Close()
errChan := make(chan error)
go func() {
for {
conn, err := listener.Accept()
if err != nil {
// don't block if parent goroutine quit early
select {
case errChan <- err:
default:
}
return
}
go serveConnection(remoteConn, conn, options)
}
}()
select {
case <-shutdownC:
return nil
case err := <-errChan:
return err
}
}
// serveConnection handles connections for the Serve() call
func serveConnection(remoteConn Connection, c net.Conn, options *StartOptions) {
defer c.Close()
_ = remoteConn.ServeStream(options, c)
}
// 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, token.AccessLoginWorkerPath) {
return true
}
return false
}
// BuildAccessRequest builds an HTTP request with the Access token set
func BuildAccessRequest(options *StartOptions, log *zerolog.Logger) (*http.Request, error) {
req, err := http.NewRequest(http.MethodGet, options.OriginURL, nil)
if err != nil {
return nil, err
}
token, err := token.FetchTokenWithRedirect(req.URL, options.AppInfo, log)
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(CFAccessTokenHeader, token)
for k, v := range options.Headers {
if len(v) >= 1 {
originRequest.Header.Set(k, v[0])
}
}
return originRequest, nil
}
func SetBastionDest(header http.Header, destination string) {
if destination != "" {
header.Set(cfJumpDestinationHeader, destination)
}
}
func ResolveBastionDest(r *http.Request) (string, error) {
jumpDestination := r.Header.Get(cfJumpDestinationHeader)
if jumpDestination == "" {
return "", fmt.Errorf("Did not receive final destination from client. The --destination flag is likely not set on the client side")
}
// Strip scheme and path set by client. Without a scheme
// Parsing a hostname and path without scheme might not return an error due to parsing ambiguities
if jumpURL, err := url.Parse(jumpDestination); err == nil && jumpURL.Host != "" {
return removePath(jumpURL.Host), nil
}
return removePath(jumpDestination), nil
}
func removePath(dest string) string {
return strings.SplitN(dest, "/", 2)[0]
}