aboutsummaryrefslogtreecommitdiff
path: root/vendor/github.com/godbus/dbus/message.go
blob: 6a925367ebe915ccdad0bef36de70106715a58ab (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
package dbus

import (
	"bytes"
	"encoding/binary"
	"errors"
	"io"
	"reflect"
	"strconv"
)

const protoVersion byte = 1

// Flags represents the possible flags of a D-Bus message.
type Flags byte

const (
	// FlagNoReplyExpected signals that the message is not expected to generate
	// a reply. If this flag is set on outgoing messages, any possible reply
	// will be discarded.
	FlagNoReplyExpected Flags = 1 << iota
	// FlagNoAutoStart signals that the message bus should not automatically
	// start an application when handling this message.
	FlagNoAutoStart
	// FlagAllowInteractiveAuthorization may be set on a method call
	// message to inform the receiving side that the caller is prepared
	// to wait for interactive authorization, which might take a
	// considerable time to complete. For instance, if this flag is set,
	// it would be appropriate to query the user for passwords or
	// confirmation via Polkit or a similar framework.
	FlagAllowInteractiveAuthorization
)

// Type represents the possible types of a D-Bus message.
type Type byte

const (
	TypeMethodCall Type = 1 + iota
	TypeMethodReply
	TypeError
	TypeSignal
	typeMax
)

func (t Type) String() string {
	switch t {
	case TypeMethodCall:
		return "method call"
	case TypeMethodReply:
		return "reply"
	case TypeError:
		return "error"
	case TypeSignal:
		return "signal"
	}
	return "invalid"
}

// HeaderField represents the possible byte codes for the headers
// of a D-Bus message.
type HeaderField byte

const (
	FieldPath HeaderField = 1 + iota
	FieldInterface
	FieldMember
	FieldErrorName
	FieldReplySerial
	FieldDestination
	FieldSender
	FieldSignature
	FieldUnixFDs
	fieldMax
)

// An InvalidMessageError describes the reason why a D-Bus message is regarded as
// invalid.
type InvalidMessageError string

func (e InvalidMessageError) Error() string {
	return "dbus: invalid message: " + string(e)
}

// fieldType are the types of the various header fields.
var fieldTypes = [fieldMax]reflect.Type{
	FieldPath:        objectPathType,
	FieldInterface:   stringType,
	FieldMember:      stringType,
	FieldErrorName:   stringType,
	FieldReplySerial: uint32Type,
	FieldDestination: stringType,
	FieldSender:      stringType,
	FieldSignature:   signatureType,
	FieldUnixFDs:     uint32Type,
}

// requiredFields lists the header fields that are required by the different
// message types.
var requiredFields = [typeMax][]HeaderField{
	TypeMethodCall:  {FieldPath, FieldMember},
	TypeMethodReply: {FieldReplySerial},
	TypeError:       {FieldErrorName, FieldReplySerial},
	TypeSignal:      {FieldPath, FieldInterface, FieldMember},
}

// Message represents a single D-Bus message.
type Message struct {
	Type
	Flags
	Headers map[HeaderField]Variant
	Body    []interface{}

	serial uint32
}

type header struct {
	Field byte
	Variant
}

// DecodeMessage tries to decode a single message in the D-Bus wire format
// from the given reader. The byte order is figured out from the first byte.
// The possibly returned error can be an error of the underlying reader, an
// InvalidMessageError or a FormatError.
func DecodeMessage(rd io.Reader) (msg *Message, err error) {
	var order binary.ByteOrder
	var hlength, length uint32
	var typ, flags, proto byte
	var headers []header

	b := make([]byte, 1)
	_, err = rd.Read(b)
	if err != nil {
		return
	}
	switch b[0] {
	case 'l':
		order = binary.LittleEndian
	case 'B':
		order = binary.BigEndian
	default:
		return nil, InvalidMessageError("invalid byte order")
	}

	dec := newDecoder(rd, order)
	dec.pos = 1

	msg = new(Message)
	vs, err := dec.Decode(Signature{"yyyuu"})
	if err != nil {
		return nil, err
	}
	if err = Store(vs, &typ, &flags, &proto, &length, &msg.serial); err != nil {
		return nil, err
	}
	msg.Type = Type(typ)
	msg.Flags = Flags(flags)

	// get the header length separately because we need it later
	b = make([]byte, 4)
	_, err = io.ReadFull(rd, b)
	if err != nil {
		return nil, err
	}
	binary.Read(bytes.NewBuffer(b), order, &hlength)
	if hlength+length+16 > 1<<27 {
		return nil, InvalidMessageError("message is too long")
	}
	dec = newDecoder(io.MultiReader(bytes.NewBuffer(b), rd), order)
	dec.pos = 12
	vs, err = dec.Decode(Signature{"a(yv)"})
	if err != nil {
		return nil, err
	}
	if err = Store(vs, &headers); err != nil {
		return nil, err
	}

	msg.Headers = make(map[HeaderField]Variant)
	for _, v := range headers {
		msg.Headers[HeaderField(v.Field)] = v.Variant
	}

	dec.align(8)
	body := make([]byte, int(length))
	if length != 0 {
		_, err := io.ReadFull(rd, body)
		if err != nil {
			return nil, err
		}
	}

	if err = msg.IsValid(); err != nil {
		return nil, err
	}
	sig, _ := msg.Headers[FieldSignature].value.(Signature)
	if sig.str != "" {
		buf := bytes.NewBuffer(body)
		dec = newDecoder(buf, order)
		vs, err := dec.Decode(sig)
		if err != nil {
			return nil, err
		}
		msg.Body = vs
	}

	return
}

// EncodeTo encodes and sends a message to the given writer. The byte order must
// be either binary.LittleEndian or binary.BigEndian. If the message is not
// valid or an error occurs when writing, an error is returned.
func (msg *Message) EncodeTo(out io.Writer, order binary.ByteOrder) error {
	if err := msg.IsValid(); err != nil {
		return err
	}
	var vs [7]interface{}
	switch order {
	case binary.LittleEndian:
		vs[0] = byte('l')
	case binary.BigEndian:
		vs[0] = byte('B')
	default:
		return errors.New("dbus: invalid byte order")
	}
	body := new(bytes.Buffer)
	enc := newEncoder(body, order)
	if len(msg.Body) != 0 {
		enc.Encode(msg.Body...)
	}
	vs[1] = msg.Type
	vs[2] = msg.Flags
	vs[3] = protoVersion
	vs[4] = uint32(len(body.Bytes()))
	vs[5] = msg.serial
	headers := make([]header, 0, len(msg.Headers))
	for k, v := range msg.Headers {
		headers = append(headers, header{byte(k), v})
	}
	vs[6] = headers
	var buf bytes.Buffer
	enc = newEncoder(&buf, order)
	enc.Encode(vs[:]...)
	enc.align(8)
	body.WriteTo(&buf)
	if buf.Len() > 1<<27 {
		return InvalidMessageError("message is too long")
	}
	if _, err := buf.WriteTo(out); err != nil {
		return err
	}
	return nil
}

// IsValid checks whether msg is a valid message and returns an
// InvalidMessageError if it is not.
func (msg *Message) IsValid() error {
	if msg.Flags & ^(FlagNoAutoStart|FlagNoReplyExpected|FlagAllowInteractiveAuthorization) != 0 {
		return InvalidMessageError("invalid flags")
	}
	if msg.Type == 0 || msg.Type >= typeMax {
		return InvalidMessageError("invalid message type")
	}
	for k, v := range msg.Headers {
		if k == 0 || k >= fieldMax {
			return InvalidMessageError("invalid header")
		}
		if reflect.TypeOf(v.value) != fieldTypes[k] {
			return InvalidMessageError("invalid type of header field")
		}
	}
	for _, v := range requiredFields[msg.Type] {
		if _, ok := msg.Headers[v]; !ok {
			return InvalidMessageError("missing required header")
		}
	}
	if path, ok := msg.Headers[FieldPath]; ok {
		if !path.value.(ObjectPath).IsValid() {
			return InvalidMessageError("invalid path name")
		}
	}
	if iface, ok := msg.Headers[FieldInterface]; ok {
		if !isValidInterface(iface.value.(string)) {
			return InvalidMessageError("invalid interface name")
		}
	}
	if member, ok := msg.Headers[FieldMember]; ok {
		if !isValidMember(member.value.(string)) {
			return InvalidMessageError("invalid member name")
		}
	}
	if errname, ok := msg.Headers[FieldErrorName]; ok {
		if !isValidInterface(errname.value.(string)) {
			return InvalidMessageError("invalid error name")
		}
	}
	if len(msg.Body) != 0 {
		if _, ok := msg.Headers[FieldSignature]; !ok {
			return InvalidMessageError("missing signature")
		}
	}
	return nil
}

// Serial returns the message's serial number. The returned value is only valid
// for messages received by eavesdropping.
func (msg *Message) Serial() uint32 {
	return msg.serial
}

// String returns a string representation of a message similar to the format of
// dbus-monitor.
func (msg *Message) String() string {
	if err := msg.IsValid(); err != nil {
		return "<invalid>"
	}
	s := msg.Type.String()
	if v, ok := msg.Headers[FieldSender]; ok {
		s += " from " + v.value.(string)
	}
	if v, ok := msg.Headers[FieldDestination]; ok {
		s += " to " + v.value.(string)
	}
	s += " serial " + strconv.FormatUint(uint64(msg.serial), 10)
	if v, ok := msg.Headers[FieldReplySerial]; ok {
		s += " reply_serial " + strconv.FormatUint(uint64(v.value.(uint32)), 10)
	}
	if v, ok := msg.Headers[FieldUnixFDs]; ok {
		s += " unixfds " + strconv.FormatUint(uint64(v.value.(uint32)), 10)
	}
	if v, ok := msg.Headers[FieldPath]; ok {
		s += " path " + string(v.value.(ObjectPath))
	}
	if v, ok := msg.Headers[FieldInterface]; ok {
		s += " interface " + v.value.(string)
	}
	if v, ok := msg.Headers[FieldErrorName]; ok {
		s += " error " + v.value.(string)
	}
	if v, ok := msg.Headers[FieldMember]; ok {
		s += " member " + v.value.(string)
	}
	if len(msg.Body) != 0 {
		s += "\n"
	}
	for i, v := range msg.Body {
		s += "  " + MakeVariant(v).String()
		if i != len(msg.Body)-1 {
			s += "\n"
		}
	}
	return s
}