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package dbus
import (
"errors"
"fmt"
"reflect"
"strings"
)
var (
ErrMsgInvalidArg = Error{
"org.freedesktop.DBus.Error.InvalidArgs",
[]interface{}{"Invalid type / number of args"},
}
ErrMsgNoObject = Error{
"org.freedesktop.DBus.Error.NoSuchObject",
[]interface{}{"No such object"},
}
ErrMsgUnknownMethod = Error{
"org.freedesktop.DBus.Error.UnknownMethod",
[]interface{}{"Unknown / invalid method"},
}
ErrMsgUnknownInterface = Error{
"org.freedesktop.DBus.Error.UnknownInterface",
[]interface{}{"Object does not implement the interface"},
}
)
func MakeFailedError(err error) *Error {
return &Error{
"org.freedesktop.DBus.Error.Failed",
[]interface{}{err.Error()},
}
}
// Sender is a type which can be used in exported methods to receive the message
// sender.
type Sender string
func computeMethodName(name string, mapping map[string]string) string {
newname, ok := mapping[name]
if ok {
name = newname
}
return name
}
func getMethods(in interface{}, mapping map[string]string) map[string]reflect.Value {
if in == nil {
return nil
}
methods := make(map[string]reflect.Value)
val := reflect.ValueOf(in)
typ := val.Type()
for i := 0; i < typ.NumMethod(); i++ {
methtype := typ.Method(i)
method := val.Method(i)
t := method.Type()
// only track valid methods must return *Error as last arg
// and must be exported
if t.NumOut() == 0 ||
t.Out(t.NumOut()-1) != reflect.TypeOf(&ErrMsgInvalidArg) ||
methtype.PkgPath != "" {
continue
}
// map names while building table
methods[computeMethodName(methtype.Name, mapping)] = method
}
return methods
}
func standardMethodArgumentDecode(m Method, sender string, msg *Message, body []interface{}) ([]interface{}, error) {
pointers := make([]interface{}, m.NumArguments())
decode := make([]interface{}, 0, len(body))
for i := 0; i < m.NumArguments(); i++ {
tp := reflect.TypeOf(m.ArgumentValue(i))
val := reflect.New(tp)
pointers[i] = val.Interface()
if tp == reflect.TypeOf((*Sender)(nil)).Elem() {
val.Elem().SetString(sender)
} else if tp == reflect.TypeOf((*Message)(nil)).Elem() {
val.Elem().Set(reflect.ValueOf(*msg))
} else {
decode = append(decode, pointers[i])
}
}
if len(decode) != len(body) {
return nil, ErrMsgInvalidArg
}
if err := Store(body, decode...); err != nil {
return nil, ErrMsgInvalidArg
}
return pointers, nil
}
func (conn *Conn) decodeArguments(m Method, sender string, msg *Message) ([]interface{}, error) {
if decoder, ok := m.(ArgumentDecoder); ok {
return decoder.DecodeArguments(conn, sender, msg, msg.Body)
}
return standardMethodArgumentDecode(m, sender, msg, msg.Body)
}
// handleCall handles the given method call (i.e. looks if it's one of the
// pre-implemented ones and searches for a corresponding handler if not).
func (conn *Conn) handleCall(msg *Message) {
name := msg.Headers[FieldMember].value.(string)
path := msg.Headers[FieldPath].value.(ObjectPath)
ifaceName, _ := msg.Headers[FieldInterface].value.(string)
sender, hasSender := msg.Headers[FieldSender].value.(string)
serial := msg.serial
if ifaceName == "org.freedesktop.DBus.Peer" {
switch name {
case "Ping":
conn.sendReply(sender, serial)
case "GetMachineId":
conn.sendReply(sender, serial, conn.uuid)
default:
conn.sendError(ErrMsgUnknownMethod, sender, serial)
}
return
}
if len(name) == 0 {
conn.sendError(ErrMsgUnknownMethod, sender, serial)
}
object, ok := conn.handler.LookupObject(path)
if !ok {
conn.sendError(ErrMsgNoObject, sender, serial)
return
}
iface, exists := object.LookupInterface(ifaceName)
if !exists {
conn.sendError(ErrMsgUnknownInterface, sender, serial)
return
}
m, exists := iface.LookupMethod(name)
if !exists {
conn.sendError(ErrMsgUnknownMethod, sender, serial)
return
}
args, err := conn.decodeArguments(m, sender, msg)
if err != nil {
conn.sendError(err, sender, serial)
return
}
ret, err := m.Call(args...)
if err != nil {
conn.sendError(err, sender, serial)
return
}
if msg.Flags&FlagNoReplyExpected == 0 {
reply := new(Message)
reply.Type = TypeMethodReply
reply.serial = conn.getSerial()
reply.Headers = make(map[HeaderField]Variant)
if hasSender {
reply.Headers[FieldDestination] = msg.Headers[FieldSender]
}
reply.Headers[FieldReplySerial] = MakeVariant(msg.serial)
reply.Body = make([]interface{}, len(ret))
for i := 0; i < len(ret); i++ {
reply.Body[i] = ret[i]
}
reply.Headers[FieldSignature] = MakeVariant(SignatureOf(reply.Body...))
conn.sendMessageAndIfClosed(reply, nil)
}
}
// Emit emits the given signal on the message bus. The name parameter must be
// formatted as "interface.member", e.g., "org.freedesktop.DBus.NameLost".
func (conn *Conn) Emit(path ObjectPath, name string, values ...interface{}) error {
if !path.IsValid() {
return errors.New("dbus: invalid object path")
}
i := strings.LastIndex(name, ".")
if i == -1 {
return errors.New("dbus: invalid method name")
}
iface := name[:i]
member := name[i+1:]
if !isValidMember(member) {
return errors.New("dbus: invalid method name")
}
if !isValidInterface(iface) {
return errors.New("dbus: invalid interface name")
}
msg := new(Message)
msg.Type = TypeSignal
msg.serial = conn.getSerial()
msg.Headers = make(map[HeaderField]Variant)
msg.Headers[FieldInterface] = MakeVariant(iface)
msg.Headers[FieldMember] = MakeVariant(member)
msg.Headers[FieldPath] = MakeVariant(path)
msg.Body = values
if len(values) > 0 {
msg.Headers[FieldSignature] = MakeVariant(SignatureOf(values...))
}
var closed bool
conn.sendMessageAndIfClosed(msg, func() {
closed = true
})
if closed {
return ErrClosed
}
return nil
}
// Export registers the given value to be exported as an object on the
// message bus.
//
// If a method call on the given path and interface is received, an exported
// method with the same name is called with v as the receiver if the
// parameters match and the last return value is of type *Error. If this
// *Error is not nil, it is sent back to the caller as an error.
// Otherwise, a method reply is sent with the other return values as its body.
//
// Any parameters with the special type Sender are set to the sender of the
// dbus message when the method is called. Parameters of this type do not
// contribute to the dbus signature of the method (i.e. the method is exposed
// as if the parameters of type Sender were not there).
//
// Similarly, any parameters with the type Message are set to the raw message
// received on the bus. Again, parameters of this type do not contribute to the
// dbus signature of the method.
//
// Every method call is executed in a new goroutine, so the method may be called
// in multiple goroutines at once.
//
// Method calls on the interface org.freedesktop.DBus.Peer will be automatically
// handled for every object.
//
// Passing nil as the first parameter will cause conn to cease handling calls on
// the given combination of path and interface.
//
// Export returns an error if path is not a valid path name.
func (conn *Conn) Export(v interface{}, path ObjectPath, iface string) error {
return conn.ExportWithMap(v, nil, path, iface)
}
// ExportWithMap works exactly like Export but provides the ability to remap
// method names (e.g. export a lower-case method).
//
// The keys in the map are the real method names (exported on the struct), and
// the values are the method names to be exported on DBus.
func (conn *Conn) ExportWithMap(v interface{}, mapping map[string]string, path ObjectPath, iface string) error {
return conn.export(getMethods(v, mapping), path, iface, false)
}
// ExportSubtree works exactly like Export but registers the given value for
// an entire subtree rather under the root path provided.
//
// In order to make this useful, one parameter in each of the value's exported
// methods should be a Message, in which case it will contain the raw message
// (allowing one to get access to the path that caused the method to be called).
//
// Note that more specific export paths take precedence over less specific. For
// example, a method call using the ObjectPath /foo/bar/baz will call a method
// exported on /foo/bar before a method exported on /foo.
func (conn *Conn) ExportSubtree(v interface{}, path ObjectPath, iface string) error {
return conn.ExportSubtreeWithMap(v, nil, path, iface)
}
// ExportSubtreeWithMap works exactly like ExportSubtree but provides the
// ability to remap method names (e.g. export a lower-case method).
//
// The keys in the map are the real method names (exported on the struct), and
// the values are the method names to be exported on DBus.
func (conn *Conn) ExportSubtreeWithMap(v interface{}, mapping map[string]string, path ObjectPath, iface string) error {
return conn.export(getMethods(v, mapping), path, iface, true)
}
// ExportMethodTable like Export registers the given methods as an object
// on the message bus. Unlike Export the it uses a method table to define
// the object instead of a native go object.
//
// The method table is a map from method name to function closure
// representing the method. This allows an object exported on the bus to not
// necessarily be a native go object. It can be useful for generating exposed
// methods on the fly.
//
// Any non-function objects in the method table are ignored.
func (conn *Conn) ExportMethodTable(methods map[string]interface{}, path ObjectPath, iface string) error {
return conn.exportMethodTable(methods, path, iface, false)
}
// Like ExportSubtree, but with the same caveats as ExportMethodTable.
func (conn *Conn) ExportSubtreeMethodTable(methods map[string]interface{}, path ObjectPath, iface string) error {
return conn.exportMethodTable(methods, path, iface, true)
}
func (conn *Conn) exportMethodTable(methods map[string]interface{}, path ObjectPath, iface string, includeSubtree bool) error {
out := make(map[string]reflect.Value)
for name, method := range methods {
rval := reflect.ValueOf(method)
if rval.Kind() != reflect.Func {
continue
}
t := rval.Type()
// only track valid methods must return *Error as last arg
if t.NumOut() == 0 ||
t.Out(t.NumOut()-1) != reflect.TypeOf(&ErrMsgInvalidArg) {
continue
}
out[name] = rval
}
return conn.export(out, path, iface, includeSubtree)
}
func (conn *Conn) unexport(h *defaultHandler, path ObjectPath, iface string) error {
if h.PathExists(path) {
obj := h.objects[path]
obj.DeleteInterface(iface)
if len(obj.interfaces) == 0 {
h.DeleteObject(path)
}
}
return nil
}
// exportWithMap is the worker function for all exports/registrations.
func (conn *Conn) export(methods map[string]reflect.Value, path ObjectPath, iface string, includeSubtree bool) error {
h, ok := conn.handler.(*defaultHandler)
if !ok {
return fmt.Errorf(
`dbus: export only allowed on the default hander handler have %T"`,
conn.handler)
}
if !path.IsValid() {
return fmt.Errorf(`dbus: Invalid path name: "%s"`, path)
}
// Remove a previous export if the interface is nil
if methods == nil {
return conn.unexport(h, path, iface)
}
// If this is the first handler for this path, make a new map to hold all
// handlers for this path.
if !h.PathExists(path) {
h.AddObject(path, newExportedObject())
}
exportedMethods := make(map[string]Method)
for name, method := range methods {
exportedMethods[name] = exportedMethod{method}
}
// Finally, save this handler
obj := h.objects[path]
obj.AddInterface(iface, newExportedIntf(exportedMethods, includeSubtree))
return nil
}
// ReleaseName calls org.freedesktop.DBus.ReleaseName and awaits a response.
func (conn *Conn) ReleaseName(name string) (ReleaseNameReply, error) {
var r uint32
err := conn.busObj.Call("org.freedesktop.DBus.ReleaseName", 0, name).Store(&r)
if err != nil {
return 0, err
}
return ReleaseNameReply(r), nil
}
// RequestName calls org.freedesktop.DBus.RequestName and awaits a response.
func (conn *Conn) RequestName(name string, flags RequestNameFlags) (RequestNameReply, error) {
var r uint32
err := conn.busObj.Call("org.freedesktop.DBus.RequestName", 0, name, flags).Store(&r)
if err != nil {
return 0, err
}
return RequestNameReply(r), nil
}
// ReleaseNameReply is the reply to a ReleaseName call.
type ReleaseNameReply uint32
const (
ReleaseNameReplyReleased ReleaseNameReply = 1 + iota
ReleaseNameReplyNonExistent
ReleaseNameReplyNotOwner
)
// RequestNameFlags represents the possible flags for a RequestName call.
type RequestNameFlags uint32
const (
NameFlagAllowReplacement RequestNameFlags = 1 << iota
NameFlagReplaceExisting
NameFlagDoNotQueue
)
// RequestNameReply is the reply to a RequestName call.
type RequestNameReply uint32
const (
RequestNameReplyPrimaryOwner RequestNameReply = 1 + iota
RequestNameReplyInQueue
RequestNameReplyExists
RequestNameReplyAlreadyOwner
)
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