package dbus import ( "errors" "io" "os" "reflect" "strings" "sync" ) const defaultSystemBusAddress = "unix:path=/var/run/dbus/system_bus_socket" var ( systemBus *Conn systemBusLck sync.Mutex sessionBus *Conn sessionBusLck sync.Mutex ) // ErrClosed is the error returned by calls on a closed connection. var ErrClosed = errors.New("dbus: connection closed by user") // Conn represents a connection to a message bus (usually, the system or // session bus). // // Connections are either shared or private. Shared connections // are shared between calls to the functions that return them. As a result, // the methods Close, Auth and Hello must not be called on them. // // Multiple goroutines may invoke methods on a connection simultaneously. type Conn struct { transport busObj BusObject unixFD bool uuid string names []string namesLck sync.RWMutex serialLck sync.Mutex nextSerial uint32 serialUsed map[uint32]bool calls map[uint32]*Call callsLck sync.RWMutex handlers map[ObjectPath]map[string]exportWithMapping handlersLck sync.RWMutex out chan *Message closed bool outLck sync.RWMutex signals []chan<- *Signal signalsLck sync.Mutex eavesdropped chan<- *Message eavesdroppedLck sync.Mutex } // SessionBus returns a shared connection to the session bus, connecting to it // if not already done. func SessionBus() (conn *Conn, err error) { sessionBusLck.Lock() defer sessionBusLck.Unlock() if sessionBus != nil { return sessionBus, nil } defer func() { if conn != nil { sessionBus = conn } }() conn, err = SessionBusPrivate() if err != nil { return } if err = conn.Auth(nil); err != nil { conn.Close() conn = nil return } if err = conn.Hello(); err != nil { conn.Close() conn = nil } return } // SessionBusPrivate returns a new private connection to the session bus. func SessionBusPrivate() (*Conn, error) { address := os.Getenv("DBUS_SESSION_BUS_ADDRESS") if address != "" && address != "autolaunch:" { return Dial(address) } return sessionBusPlatform() } // SystemBus returns a shared connection to the system bus, connecting to it if // not already done. func SystemBus() (conn *Conn, err error) { systemBusLck.Lock() defer systemBusLck.Unlock() if systemBus != nil { return systemBus, nil } defer func() { if conn != nil { systemBus = conn } }() conn, err = SystemBusPrivate() if err != nil { return } if err = conn.Auth(nil); err != nil { conn.Close() conn = nil return } if err = conn.Hello(); err != nil { conn.Close() conn = nil } return } // SystemBusPrivate returns a new private connection to the system bus. func SystemBusPrivate() (*Conn, error) { address := os.Getenv("DBUS_SYSTEM_BUS_ADDRESS") if address != "" { return Dial(address) } return Dial(defaultSystemBusAddress) } // Dial establishes a new private connection to the message bus specified by address. func Dial(address string) (*Conn, error) { tr, err := getTransport(address) if err != nil { return nil, err } return newConn(tr) } // NewConn creates a new private *Conn from an already established connection. func NewConn(conn io.ReadWriteCloser) (*Conn, error) { return newConn(genericTransport{conn}) } // newConn creates a new *Conn from a transport. func newConn(tr transport) (*Conn, error) { conn := new(Conn) conn.transport = tr conn.calls = make(map[uint32]*Call) conn.out = make(chan *Message, 10) conn.handlers = make(map[ObjectPath]map[string]exportWithMapping) conn.nextSerial = 1 conn.serialUsed = map[uint32]bool{0: true} conn.busObj = conn.Object("org.freedesktop.DBus", "/org/freedesktop/DBus") return conn, nil } // BusObject returns the object owned by the bus daemon which handles // administrative requests. func (conn *Conn) BusObject() BusObject { return conn.busObj } // Close closes the connection. Any blocked operations will return with errors // and the channels passed to Eavesdrop and Signal are closed. This method must // not be called on shared connections. func (conn *Conn) Close() error { conn.outLck.Lock() if conn.closed { // inWorker calls Close on read error, the read error may // be caused by another caller calling Close to shutdown the // dbus connection, a double-close scenario we prevent here. conn.outLck.Unlock() return nil } close(conn.out) conn.closed = true conn.outLck.Unlock() conn.signalsLck.Lock() for _, ch := range conn.signals { close(ch) } conn.signalsLck.Unlock() conn.eavesdroppedLck.Lock() if conn.eavesdropped != nil { close(conn.eavesdropped) } conn.eavesdroppedLck.Unlock() return conn.transport.Close() } // Eavesdrop causes conn to send all incoming messages to the given channel // without further processing. Method replies, errors and signals will not be // sent to the appropiate channels and method calls will not be handled. If nil // is passed, the normal behaviour is restored. // // The caller has to make sure that ch is sufficiently buffered; // if a message arrives when a write to ch is not possible, the message is // discarded. func (conn *Conn) Eavesdrop(ch chan<- *Message) { conn.eavesdroppedLck.Lock() conn.eavesdropped = ch conn.eavesdroppedLck.Unlock() } // getSerial returns an unused serial. func (conn *Conn) getSerial() uint32 { conn.serialLck.Lock() defer conn.serialLck.Unlock() n := conn.nextSerial for conn.serialUsed[n] { n++ } conn.serialUsed[n] = true conn.nextSerial = n + 1 return n } // Hello sends the initial org.freedesktop.DBus.Hello call. This method must be // called after authentication, but before sending any other messages to the // bus. Hello must not be called for shared connections. func (conn *Conn) Hello() error { var s string err := conn.busObj.Call("org.freedesktop.DBus.Hello", 0).Store(&s) if err != nil { return err } conn.namesLck.Lock() conn.names = make([]string, 1) conn.names[0] = s conn.namesLck.Unlock() return nil } // inWorker runs in an own goroutine, reading incoming messages from the // transport and dispatching them appropiately. func (conn *Conn) inWorker() { for { msg, err := conn.ReadMessage() if err == nil { conn.eavesdroppedLck.Lock() if conn.eavesdropped != nil { select { case conn.eavesdropped <- msg: default: } conn.eavesdroppedLck.Unlock() continue } conn.eavesdroppedLck.Unlock() dest, _ := msg.Headers[FieldDestination].value.(string) found := false if dest == "" { found = true } else { conn.namesLck.RLock() if len(conn.names) == 0 { found = true } for _, v := range conn.names { if dest == v { found = true break } } conn.namesLck.RUnlock() } if !found { // Eavesdropped a message, but no channel for it is registered. // Ignore it. continue } switch msg.Type { case TypeMethodReply, TypeError: serial := msg.Headers[FieldReplySerial].value.(uint32) conn.callsLck.Lock() if c, ok := conn.calls[serial]; ok { if msg.Type == TypeError { name, _ := msg.Headers[FieldErrorName].value.(string) c.Err = Error{name, msg.Body} } else { c.Body = msg.Body } c.Done <- c conn.serialLck.Lock() delete(conn.serialUsed, serial) conn.serialLck.Unlock() delete(conn.calls, serial) } conn.callsLck.Unlock() case TypeSignal: iface := msg.Headers[FieldInterface].value.(string) member := msg.Headers[FieldMember].value.(string) // as per http://dbus.freedesktop.org/doc/dbus-specification.html , // sender is optional for signals. sender, _ := msg.Headers[FieldSender].value.(string) if iface == "org.freedesktop.DBus" && sender == "org.freedesktop.DBus" { if member == "NameLost" { // If we lost the name on the bus, remove it from our // tracking list. name, ok := msg.Body[0].(string) if !ok { panic("Unable to read the lost name") } conn.namesLck.Lock() for i, v := range conn.names { if v == name { conn.names = append(conn.names[:i], conn.names[i+1:]...) } } conn.namesLck.Unlock() } else if member == "NameAcquired" { // If we acquired the name on the bus, add it to our // tracking list. name, ok := msg.Body[0].(string) if !ok { panic("Unable to read the acquired name") } conn.namesLck.Lock() conn.names = append(conn.names, name) conn.namesLck.Unlock() } } signal := &Signal{ Sender: sender, Path: msg.Headers[FieldPath].value.(ObjectPath), Name: iface + "." + member, Body: msg.Body, } conn.signalsLck.Lock() for _, ch := range conn.signals { ch <- signal } conn.signalsLck.Unlock() case TypeMethodCall: go conn.handleCall(msg) } } else if _, ok := err.(InvalidMessageError); !ok { // Some read error occured (usually EOF); we can't really do // anything but to shut down all stuff and returns errors to all // pending replies. conn.Close() conn.callsLck.RLock() for _, v := range conn.calls { v.Err = err v.Done <- v } conn.callsLck.RUnlock() return } // invalid messages are ignored } } // Names returns the list of all names that are currently owned by this // connection. The slice is always at least one element long, the first element // being the unique name of the connection. func (conn *Conn) Names() []string { conn.namesLck.RLock() // copy the slice so it can't be modified s := make([]string, len(conn.names)) copy(s, conn.names) conn.namesLck.RUnlock() return s } // Object returns the object identified by the given destination name and path. func (conn *Conn) Object(dest string, path ObjectPath) BusObject { return &Object{conn, dest, path} } // outWorker runs in an own goroutine, encoding and sending messages that are // sent to conn.out. func (conn *Conn) outWorker() { for msg := range conn.out { err := conn.SendMessage(msg) conn.callsLck.RLock() if err != nil { if c := conn.calls[msg.serial]; c != nil { c.Err = err c.Done <- c } conn.serialLck.Lock() delete(conn.serialUsed, msg.serial) conn.serialLck.Unlock() } else if msg.Type != TypeMethodCall { conn.serialLck.Lock() delete(conn.serialUsed, msg.serial) conn.serialLck.Unlock() } conn.callsLck.RUnlock() } } // Send sends the given message to the message bus. You usually don't need to // use this; use the higher-level equivalents (Call / Go, Emit and Export) // instead. If msg is a method call and NoReplyExpected is not set, a non-nil // call is returned and the same value is sent to ch (which must be buffered) // once the call is complete. Otherwise, ch is ignored and a Call structure is // returned of which only the Err member is valid. func (conn *Conn) Send(msg *Message, ch chan *Call) *Call { var call *Call msg.serial = conn.getSerial() if msg.Type == TypeMethodCall && msg.Flags&FlagNoReplyExpected == 0 { if ch == nil { ch = make(chan *Call, 5) } else if cap(ch) == 0 { panic("dbus: unbuffered channel passed to (*Conn).Send") } call = new(Call) call.Destination, _ = msg.Headers[FieldDestination].value.(string) call.Path, _ = msg.Headers[FieldPath].value.(ObjectPath) iface, _ := msg.Headers[FieldInterface].value.(string) member, _ := msg.Headers[FieldMember].value.(string) call.Method = iface + "." + member call.Args = msg.Body call.Done = ch conn.callsLck.Lock() conn.calls[msg.serial] = call conn.callsLck.Unlock() conn.outLck.RLock() if conn.closed { call.Err = ErrClosed call.Done <- call } else { conn.out <- msg } conn.outLck.RUnlock() } else { conn.outLck.RLock() if conn.closed { call = &Call{Err: ErrClosed} } else { conn.out <- msg call = &Call{Err: nil} } conn.outLck.RUnlock() } return call } // sendError creates an error message corresponding to the parameters and sends // it to conn.out. func (conn *Conn) sendError(e Error, dest string, serial uint32) { msg := new(Message) msg.Type = TypeError msg.serial = conn.getSerial() msg.Headers = make(map[HeaderField]Variant) if dest != "" { msg.Headers[FieldDestination] = MakeVariant(dest) } msg.Headers[FieldErrorName] = MakeVariant(e.Name) msg.Headers[FieldReplySerial] = MakeVariant(serial) msg.Body = e.Body if len(e.Body) > 0 { msg.Headers[FieldSignature] = MakeVariant(SignatureOf(e.Body...)) } conn.outLck.RLock() if !conn.closed { conn.out <- msg } conn.outLck.RUnlock() } // sendReply creates a method reply message corresponding to the parameters and // sends it to conn.out. func (conn *Conn) sendReply(dest string, serial uint32, values ...interface{}) { msg := new(Message) msg.Type = TypeMethodReply msg.serial = conn.getSerial() msg.Headers = make(map[HeaderField]Variant) if dest != "" { msg.Headers[FieldDestination] = MakeVariant(dest) } msg.Headers[FieldReplySerial] = MakeVariant(serial) msg.Body = values if len(values) > 0 { msg.Headers[FieldSignature] = MakeVariant(SignatureOf(values...)) } conn.outLck.RLock() if !conn.closed { conn.out <- msg } conn.outLck.RUnlock() } // Signal registers the given channel to be passed all received signal messages. // The caller has to make sure that ch is sufficiently buffered; if a message // arrives when a write to c is not possible, it is discarded. // // Multiple of these channels can be registered at the same time. Passing a // channel that already is registered will remove it from the list of the // registered channels. // // These channels are "overwritten" by Eavesdrop; i.e., if there currently is a // channel for eavesdropped messages, this channel receives all signals, and // none of the channels passed to Signal will receive any signals. func (conn *Conn) Signal(ch chan<- *Signal) { conn.signalsLck.Lock() conn.signals = append(conn.signals, ch) conn.signalsLck.Unlock() } // SupportsUnixFDs returns whether the underlying transport supports passing of // unix file descriptors. If this is false, method calls containing unix file // descriptors will return an error and emitted signals containing them will // not be sent. func (conn *Conn) SupportsUnixFDs() bool { return conn.unixFD } // Error represents a D-Bus message of type Error. type Error struct { Name string Body []interface{} } func NewError(name string, body []interface{}) *Error { return &Error{name, body} } func (e Error) Error() string { if len(e.Body) >= 1 { s, ok := e.Body[0].(string) if ok { return s } } return e.Name } // Signal represents a D-Bus message of type Signal. The name member is given in // "interface.member" notation, e.g. org.freedesktop.D-Bus.NameLost. type Signal struct { Sender string Path ObjectPath Name string Body []interface{} } // transport is a D-Bus transport. type transport interface { // Read and Write raw data (for example, for the authentication protocol). io.ReadWriteCloser // Send the initial null byte used for the EXTERNAL mechanism. SendNullByte() error // Returns whether this transport supports passing Unix FDs. SupportsUnixFDs() bool // Signal the transport that Unix FD passing is enabled for this connection. EnableUnixFDs() // Read / send a message, handling things like Unix FDs. ReadMessage() (*Message, error) SendMessage(*Message) error } var ( transports = make(map[string]func(string) (transport, error)) ) func getTransport(address string) (transport, error) { var err error var t transport addresses := strings.Split(address, ";") for _, v := range addresses { i := strings.IndexRune(v, ':') if i == -1 { err = errors.New("dbus: invalid bus address (no transport)") continue } f := transports[v[:i]] if f == nil { err = errors.New("dbus: invalid bus address (invalid or unsupported transport)") continue } t, err = f(v[i+1:]) if err == nil { return t, nil } } return nil, err } // dereferenceAll returns a slice that, assuming that vs is a slice of pointers // of arbitrary types, containes the values that are obtained from dereferencing // all elements in vs. func dereferenceAll(vs []interface{}) []interface{} { for i := range vs { v := reflect.ValueOf(vs[i]) v = v.Elem() vs[i] = v.Interface() } return vs } // getKey gets a key from a the list of keys. Returns "" on error / not found... func getKey(s, key string) string { i := strings.Index(s, key) if i == -1 { return "" } if i+len(key)+1 >= len(s) || s[i+len(key)] != '=' { return "" } j := strings.Index(s, ",") if j == -1 { j = len(s) } return s[i+len(key)+1 : j] }