cloudflare/cloudflared
Publicmirrored from https://github.com/cloudflare/cloudflaredAvailable
carrier/carrier.go
185lines · modecode
| 1 | // Package carrier provides a WebSocket proxy to carry or proxy a connection |
| 2 | // from the local client to the edge. See it as a wrapper around any protocol |
| 3 | // that it packages up in a WebSocket connection to the edge. |
| 4 | package carrier |
| 5 | |
| 6 | import ( |
| 7 | "crypto/tls" |
| 8 | "fmt" |
| 9 | "io" |
| 10 | "net" |
| 11 | "net/http" |
| 12 | "net/url" |
| 13 | "os" |
| 14 | "strings" |
| 15 | |
| 16 | "github.com/pkg/errors" |
| 17 | "github.com/rs/zerolog" |
| 18 | |
| 19 | "github.com/cloudflare/cloudflared/token" |
| 20 | ) |
| 21 | |
| 22 | const ( |
| 23 | LogFieldOriginURL = "originURL" |
| 24 | CFAccessTokenHeader = "Cf-Access-Token" |
| 25 | cfJumpDestinationHeader = "Cf-Access-Jump-Destination" |
| 26 | ) |
| 27 | |
| 28 | type StartOptions struct { |
| 29 | AppInfo *token.AppInfo |
| 30 | OriginURL string |
| 31 | Headers http.Header |
| 32 | Host string |
| 33 | TLSClientConfig *tls.Config |
| 34 | } |
| 35 | |
| 36 | // Connection wraps up all the needed functions to forward over the tunnel |
| 37 | type Connection interface { |
| 38 | // ServeStream is used to forward data from the client to the edge |
| 39 | ServeStream(*StartOptions, io.ReadWriter) error |
| 40 | } |
| 41 | |
| 42 | // StdinoutStream is empty struct for wrapping stdin/stdout |
| 43 | // into a single ReadWriter |
| 44 | type StdinoutStream struct{} |
| 45 | |
| 46 | // Read will read from Stdin |
| 47 | func (c *StdinoutStream) Read(p []byte) (int, error) { |
| 48 | return os.Stdin.Read(p) |
| 49 | |
| 50 | } |
| 51 | |
| 52 | // Write will write to Stdout |
| 53 | func (c *StdinoutStream) Write(p []byte) (int, error) { |
| 54 | return os.Stdout.Write(p) |
| 55 | } |
| 56 | |
| 57 | // Helper to allow deferring the response close with a check that the resp is not nil |
| 58 | func closeRespBody(resp *http.Response) { |
| 59 | if resp != nil { |
| 60 | _ = resp.Body.Close() |
| 61 | } |
| 62 | } |
| 63 | |
| 64 | // StartForwarder will setup a listener on a specified address/port and then |
| 65 | // forward connections to the origin by calling `Serve()`. |
| 66 | func StartForwarder(conn Connection, address string, shutdownC <-chan struct{}, options *StartOptions) error { |
| 67 | listener, err := net.Listen("tcp", address) |
| 68 | if err != nil { |
| 69 | return errors.Wrap(err, "failed to start forwarding server") |
| 70 | } |
| 71 | return Serve(conn, listener, shutdownC, options) |
| 72 | } |
| 73 | |
| 74 | // StartClient will copy the data from stdin/stdout over a WebSocket connection |
| 75 | // to the edge (originURL) |
| 76 | func StartClient(conn Connection, stream io.ReadWriter, options *StartOptions) error { |
| 77 | return conn.ServeStream(options, stream) |
| 78 | } |
| 79 | |
| 80 | // Serve accepts incoming connections on the specified net.Listener. |
| 81 | // Each connection is handled in a new goroutine: its data is copied over a |
| 82 | // WebSocket connection to the edge (originURL). |
| 83 | // `Serve` always closes `listener`. |
| 84 | func Serve(remoteConn Connection, listener net.Listener, shutdownC <-chan struct{}, options *StartOptions) error { |
| 85 | defer listener.Close() |
| 86 | errChan := make(chan error) |
| 87 | |
| 88 | go func() { |
| 89 | for { |
| 90 | conn, err := listener.Accept() |
| 91 | if err != nil { |
| 92 | // don't block if parent goroutine quit early |
| 93 | select { |
| 94 | case errChan <- err: |
| 95 | default: |
| 96 | } |
| 97 | return |
| 98 | } |
| 99 | go serveConnection(remoteConn, conn, options) |
| 100 | } |
| 101 | }() |
| 102 | |
| 103 | select { |
| 104 | case <-shutdownC: |
| 105 | return nil |
| 106 | case err := <-errChan: |
| 107 | return err |
| 108 | } |
| 109 | } |
| 110 | |
| 111 | // serveConnection handles connections for the Serve() call |
| 112 | func serveConnection(remoteConn Connection, c net.Conn, options *StartOptions) { |
| 113 | defer c.Close() |
| 114 | _ = remoteConn.ServeStream(options, c) |
| 115 | } |
| 116 | |
| 117 | // IsAccessResponse checks the http Response to see if the url location |
| 118 | // contains the Access structure. |
| 119 | func IsAccessResponse(resp *http.Response) bool { |
| 120 | if resp == nil || resp.StatusCode != http.StatusFound { |
| 121 | return false |
| 122 | } |
| 123 | |
| 124 | location, err := resp.Location() |
| 125 | if err != nil || location == nil { |
| 126 | return false |
| 127 | } |
| 128 | if strings.HasPrefix(location.Path, token.AccessLoginWorkerPath) { |
| 129 | return true |
| 130 | } |
| 131 | |
| 132 | return false |
| 133 | } |
| 134 | |
| 135 | // BuildAccessRequest builds an HTTP request with the Access token set |
| 136 | func BuildAccessRequest(options *StartOptions, log *zerolog.Logger) (*http.Request, error) { |
| 137 | req, err := http.NewRequest(http.MethodGet, options.OriginURL, nil) |
| 138 | if err != nil { |
| 139 | return nil, err |
| 140 | } |
| 141 | |
| 142 | token, err := token.FetchTokenWithRedirect(req.URL, options.AppInfo, log) |
| 143 | if err != nil { |
| 144 | return nil, err |
| 145 | } |
| 146 | |
| 147 | // We need to create a new request as FetchToken will modify req (boo mutable) |
| 148 | // as it has to follow redirect on the API and such, so here we init a new one |
| 149 | originRequest, err := http.NewRequest(http.MethodGet, options.OriginURL, nil) |
| 150 | if err != nil { |
| 151 | return nil, err |
| 152 | } |
| 153 | originRequest.Header.Set(CFAccessTokenHeader, token) |
| 154 | |
| 155 | for k, v := range options.Headers { |
| 156 | if len(v) >= 1 { |
| 157 | originRequest.Header.Set(k, v[0]) |
| 158 | } |
| 159 | } |
| 160 | |
| 161 | return originRequest, nil |
| 162 | } |
| 163 | |
| 164 | func SetBastionDest(header http.Header, destination string) { |
| 165 | if destination != "" { |
| 166 | header.Set(cfJumpDestinationHeader, destination) |
| 167 | } |
| 168 | } |
| 169 | |
| 170 | func ResolveBastionDest(r *http.Request) (string, error) { |
| 171 | jumpDestination := r.Header.Get(cfJumpDestinationHeader) |
| 172 | if jumpDestination == "" { |
| 173 | return "", fmt.Errorf("Did not receive final destination from client. The --destination flag is likely not set on the client side") |
| 174 | } |
| 175 | // Strip scheme and path set by client. Without a scheme |
| 176 | // Parsing a hostname and path without scheme might not return an error due to parsing ambiguities |
| 177 | if jumpURL, err := url.Parse(jumpDestination); err == nil && jumpURL.Host != "" { |
| 178 | return removePath(jumpURL.Host), nil |
| 179 | } |
| 180 | return removePath(jumpDestination), nil |
| 181 | } |
| 182 | |
| 183 | func removePath(dest string) string { |
| 184 | return strings.SplitN(dest, "/", 2)[0] |
| 185 | } |