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185 lines
5.1 KiB
185 lines
5.1 KiB
//Package carrier provides a WebSocket proxy to carry or proxy a connection |
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//from the local client to the edge. See it as a wrapper around any protocol |
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//that it packages up in a WebSocket connection to the edge. |
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package carrier |
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import ( |
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"crypto/tls" |
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"fmt" |
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"io" |
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"net" |
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"net/http" |
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"net/url" |
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"os" |
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"strings" |
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"github.com/pkg/errors" |
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"github.com/rs/zerolog" |
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"github.com/cloudflare/cloudflared/token" |
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) |
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const ( |
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LogFieldOriginURL = "originURL" |
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CFAccessTokenHeader = "Cf-Access-Token" |
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cfJumpDestinationHeader = "Cf-Access-Jump-Destination" |
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) |
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type StartOptions struct { |
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AppInfo *token.AppInfo |
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OriginURL string |
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Headers http.Header |
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Host string |
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TLSClientConfig *tls.Config |
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} |
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// Connection wraps up all the needed functions to forward over the tunnel |
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type Connection interface { |
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// ServeStream is used to forward data from the client to the edge |
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ServeStream(*StartOptions, io.ReadWriter) error |
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} |
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// StdinoutStream is empty struct for wrapping stdin/stdout |
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// into a single ReadWriter |
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type StdinoutStream struct{} |
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// Read will read from Stdin |
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func (c *StdinoutStream) Read(p []byte) (int, error) { |
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return os.Stdin.Read(p) |
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} |
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// Write will write to Stdout |
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func (c *StdinoutStream) Write(p []byte) (int, error) { |
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return os.Stdout.Write(p) |
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} |
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// Helper to allow deferring the response close with a check that the resp is not nil |
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func closeRespBody(resp *http.Response) { |
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if resp != nil { |
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_ = resp.Body.Close() |
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} |
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} |
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// StartForwarder will setup a listener on a specified address/port and then |
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// forward connections to the origin by calling `Serve()`. |
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func StartForwarder(conn Connection, address string, shutdownC <-chan struct{}, options *StartOptions) error { |
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listener, err := net.Listen("tcp", address) |
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if err != nil { |
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return errors.Wrap(err, "failed to start forwarding server") |
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} |
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return Serve(conn, listener, shutdownC, options) |
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} |
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// StartClient will copy the data from stdin/stdout over a WebSocket connection |
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// to the edge (originURL) |
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func StartClient(conn Connection, stream io.ReadWriter, options *StartOptions) error { |
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return conn.ServeStream(options, stream) |
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} |
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// Serve accepts incoming connections on the specified net.Listener. |
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// Each connection is handled in a new goroutine: its data is copied over a |
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// WebSocket connection to the edge (originURL). |
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// `Serve` always closes `listener`. |
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func Serve(remoteConn Connection, listener net.Listener, shutdownC <-chan struct{}, options *StartOptions) error { |
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defer listener.Close() |
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errChan := make(chan error) |
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go func() { |
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for { |
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conn, err := listener.Accept() |
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if err != nil { |
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// don't block if parent goroutine quit early |
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select { |
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case errChan <- err: |
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default: |
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} |
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return |
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} |
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go serveConnection(remoteConn, conn, options) |
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} |
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}() |
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select { |
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case <-shutdownC: |
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return nil |
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case err := <-errChan: |
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return err |
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} |
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} |
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// serveConnection handles connections for the Serve() call |
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func serveConnection(remoteConn Connection, c net.Conn, options *StartOptions) { |
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defer c.Close() |
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_ = remoteConn.ServeStream(options, c) |
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} |
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// IsAccessResponse checks the http Response to see if the url location |
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// contains the Access structure. |
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func IsAccessResponse(resp *http.Response) bool { |
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if resp == nil || resp.StatusCode != http.StatusFound { |
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return false |
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} |
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location, err := resp.Location() |
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if err != nil || location == nil { |
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return false |
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} |
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if strings.HasPrefix(location.Path, token.AccessLoginWorkerPath) { |
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return true |
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} |
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return false |
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} |
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// BuildAccessRequest builds an HTTP request with the Access token set |
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func BuildAccessRequest(options *StartOptions, log *zerolog.Logger) (*http.Request, error) { |
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req, err := http.NewRequest(http.MethodGet, options.OriginURL, nil) |
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if err != nil { |
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return nil, err |
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} |
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token, err := token.FetchTokenWithRedirect(req.URL, options.AppInfo, log) |
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if err != nil { |
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return nil, err |
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} |
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// We need to create a new request as FetchToken will modify req (boo mutable) |
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// as it has to follow redirect on the API and such, so here we init a new one |
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originRequest, err := http.NewRequest(http.MethodGet, options.OriginURL, nil) |
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if err != nil { |
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return nil, err |
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} |
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originRequest.Header.Set(CFAccessTokenHeader, token) |
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for k, v := range options.Headers { |
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if len(v) >= 1 { |
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originRequest.Header.Set(k, v[0]) |
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} |
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} |
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return originRequest, nil |
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} |
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func SetBastionDest(header http.Header, destination string) { |
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if destination != "" { |
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header.Set(cfJumpDestinationHeader, destination) |
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} |
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} |
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func ResolveBastionDest(r *http.Request) (string, error) { |
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jumpDestination := r.Header.Get(cfJumpDestinationHeader) |
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if jumpDestination == "" { |
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return "", fmt.Errorf("Did not receive final destination from client. The --destination flag is likely not set on the client side") |
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} |
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// Strip scheme and path set by client. Without a scheme |
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// Parsing a hostname and path without scheme might not return an error due to parsing ambiguities |
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if jumpURL, err := url.Parse(jumpDestination); err == nil && jumpURL.Host != "" { |
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return removePath(jumpURL.Host), nil |
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} |
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return removePath(jumpDestination), nil |
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} |
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func removePath(dest string) string { |
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return strings.SplitN(dest, "/", 2)[0] |
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}
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