256 lines
6.7 KiB
Go
256 lines
6.7 KiB
Go
package dbus
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import (
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"bufio"
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"bytes"
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"errors"
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"io"
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"os/user"
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)
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// AuthStatus represents the Status of an authentication mechanism.
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type AuthStatus byte
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const (
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// AuthOk signals that authentication is finished; the next command
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// from the server should be an OK.
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AuthOk AuthStatus = iota
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// AuthContinue signals that additional data is needed; the next command
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// from the server should be a DATA.
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AuthContinue
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// AuthError signals an error; the server sent invalid data or some
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// other unexpected thing happened and the current authentication
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// process should be aborted.
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AuthError
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)
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type authState byte
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const (
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waitingForData authState = iota
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waitingForOk
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waitingForReject
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)
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// Auth defines the behaviour of an authentication mechanism.
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type Auth interface {
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// Return the name of the mechnism, the argument to the first AUTH command
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// and the next status.
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FirstData() (name, resp []byte, status AuthStatus)
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// Process the given DATA command, and return the argument to the DATA
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// command and the next status. If len(resp) == 0, no DATA command is sent.
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HandleData(data []byte) (resp []byte, status AuthStatus)
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}
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// Auth authenticates the connection, trying the given list of authentication
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// mechanisms (in that order). If nil is passed, the EXTERNAL and
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// DBUS_COOKIE_SHA1 mechanisms are tried for the current user. For private
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// connections, this method must be called before sending any messages to the
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// bus. Auth must not be called on shared connections.
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func (conn *Conn) Auth(methods []Auth) error {
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if methods == nil {
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u, err := user.Current()
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if err != nil {
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return err
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}
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methods = []Auth{AuthExternal(u.Username), AuthCookieSha1(u.Username, u.HomeDir)}
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}
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in := bufio.NewReader(conn.transport)
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err := conn.transport.SendNullByte()
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if err != nil {
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return err
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}
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err = authWriteLine(conn.transport, []byte("AUTH"))
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if err != nil {
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return err
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}
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s, err := authReadLine(in)
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if err != nil {
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return err
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}
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if len(s) < 2 || !bytes.Equal(s[0], []byte("REJECTED")) {
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return errors.New("dbus: authentication protocol error")
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}
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s = s[1:]
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for _, v := range s {
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for _, m := range methods {
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if name, data, status := m.FirstData(); bytes.Equal(v, name) {
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var ok bool
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err = authWriteLine(conn.transport, []byte("AUTH"), []byte(v), data)
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if err != nil {
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return err
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}
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switch status {
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case AuthOk:
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err, ok = conn.tryAuth(m, waitingForOk, in)
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case AuthContinue:
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err, ok = conn.tryAuth(m, waitingForData, in)
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default:
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panic("dbus: invalid authentication status")
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}
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if err != nil {
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return err
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}
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if ok {
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if conn.transport.SupportsUnixFDs() {
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err = authWriteLine(conn, []byte("NEGOTIATE_UNIX_FD"))
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if err != nil {
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return err
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}
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line, err := authReadLine(in)
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if err != nil {
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return err
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}
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switch {
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case bytes.Equal(line[0], []byte("AGREE_UNIX_FD")):
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conn.EnableUnixFDs()
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conn.unixFD = true
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case bytes.Equal(line[0], []byte("ERROR")):
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default:
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return errors.New("dbus: authentication protocol error")
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}
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}
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err = authWriteLine(conn.transport, []byte("BEGIN"))
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if err != nil {
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return err
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}
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go conn.inWorker()
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go conn.outWorker()
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return nil
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}
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}
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}
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}
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return errors.New("dbus: authentication failed")
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}
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// tryAuth tries to authenticate with m as the mechanism, using state as the
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// initial authState and in for reading input. It returns (nil, true) on
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// success, (nil, false) on a REJECTED and (someErr, false) if some other
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// error occured.
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func (conn *Conn) tryAuth(m Auth, state authState, in *bufio.Reader) (error, bool) {
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for {
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s, err := authReadLine(in)
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if err != nil {
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return err, false
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}
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switch {
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case state == waitingForData && string(s[0]) == "DATA":
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if len(s) != 2 {
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err = authWriteLine(conn.transport, []byte("ERROR"))
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if err != nil {
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return err, false
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}
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continue
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}
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data, status := m.HandleData(s[1])
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switch status {
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case AuthOk, AuthContinue:
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if len(data) != 0 {
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err = authWriteLine(conn.transport, []byte("DATA"), data)
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if err != nil {
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return err, false
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}
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}
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if status == AuthOk {
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state = waitingForOk
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}
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case AuthError:
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err = authWriteLine(conn.transport, []byte("ERROR"))
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if err != nil {
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return err, false
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}
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}
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case state == waitingForData && string(s[0]) == "REJECTED":
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return nil, false
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case state == waitingForData && string(s[0]) == "ERROR":
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err = authWriteLine(conn.transport, []byte("CANCEL"))
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if err != nil {
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return err, false
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}
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state = waitingForReject
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case state == waitingForData && string(s[0]) == "OK":
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if len(s) != 2 {
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err = authWriteLine(conn.transport, []byte("CANCEL"))
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if err != nil {
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return err, false
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}
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state = waitingForReject
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}
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conn.uuid = string(s[1])
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return nil, true
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case state == waitingForData:
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err = authWriteLine(conn.transport, []byte("ERROR"))
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if err != nil {
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return err, false
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}
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case state == waitingForOk && string(s[0]) == "OK":
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if len(s) != 2 {
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err = authWriteLine(conn.transport, []byte("CANCEL"))
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if err != nil {
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return err, false
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}
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state = waitingForReject
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}
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conn.uuid = string(s[1])
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return nil, true
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case state == waitingForOk && string(s[0]) == "REJECTED":
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return nil, false
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case state == waitingForOk && (string(s[0]) == "DATA" ||
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string(s[0]) == "ERROR"):
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err = authWriteLine(conn.transport, []byte("CANCEL"))
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if err != nil {
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return err, false
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}
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state = waitingForReject
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case state == waitingForOk:
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err = authWriteLine(conn.transport, []byte("ERROR"))
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if err != nil {
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return err, false
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}
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case state == waitingForReject && string(s[0]) == "REJECTED":
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return nil, false
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case state == waitingForReject:
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return errors.New("dbus: authentication protocol error"), false
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default:
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panic("dbus: invalid auth state")
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}
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}
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}
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// authReadLine reads a line and separates it into its fields.
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func authReadLine(in *bufio.Reader) ([][]byte, error) {
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data, err := in.ReadBytes('\n')
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if err != nil {
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return nil, err
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}
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data = bytes.TrimSuffix(data, []byte("\r\n"))
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return bytes.Split(data, []byte{' '}), nil
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}
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// authWriteLine writes the given line in the authentication protocol format
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// (elements of data separated by a " " and terminated by "\r\n").
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func authWriteLine(out io.Writer, data ...[]byte) error {
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buf := make([]byte, 0)
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for i, v := range data {
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buf = append(buf, v...)
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if i != len(data)-1 {
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buf = append(buf, ' ')
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}
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}
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buf = append(buf, '\r')
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buf = append(buf, '\n')
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n, err := out.Write(buf)
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if err != nil {
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return err
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}
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if n != len(buf) {
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return io.ErrUnexpectedEOF
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}
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return nil
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}
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