xref: /btstack/src/classic/goep_client.c (revision d58a1b5f11ada8ddf896c41fff5a35e7f140c37e)
1 /*
2  * Copyright (C) 2014 BlueKitchen GmbH
3  *
4  * Redistribution and use in source and binary forms, with or without
5  * modification, are permitted provided that the following conditions
6  * are met:
7  *
8  * 1. Redistributions of source code must retain the above copyright
9  *    notice, this list of conditions and the following disclaimer.
10  * 2. Redistributions in binary form must reproduce the above copyright
11  *    notice, this list of conditions and the following disclaimer in the
12  *    documentation and/or other materials provided with the distribution.
13  * 3. Neither the name of the copyright holders nor the names of
14  *    contributors may be used to endorse or promote products derived
15  *    from this software without specific prior written permission.
16  * 4. Any redistribution, use, or modification is done solely for
17  *    personal benefit and not for any commercial purpose or for
18  *    monetary gain.
19  *
20  * THIS SOFTWARE IS PROVIDED BY BLUEKITCHEN GMBH AND CONTRIBUTORS
21  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
22  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
23  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
24  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
25  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
26  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
27  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
28  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
29  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
32  *
33  * Please inquire about commercial licensing options at
34  * [email protected]
35  *
36  */
37 
38 #define BTSTACK_FILE__ "goep_client.c"
39 
40 #include "btstack_config.h"
41 
42 #include <stdint.h>
43 #include <stdio.h>
44 #include <stdlib.h>
45 #include <string.h>
46 
47 #include "btstack_debug.h"
48 #include "hci_dump.h"
49 #include "bluetooth_sdp.h"
50 #include "btstack_event.h"
51 #include "classic/goep_client.h"
52 #include "classic/obex_message_builder.h"
53 #include "classic/obex.h"
54 #include "classic/obex_iterator.h"
55 #include "classic/rfcomm.h"
56 #include "classic/sdp_client.h"
57 #include "classic/sdp_util.h"
58 #include "l2cap.h"
59 
60 //------------------------------------------------------------------------------------------------------------
61 // goep_client.c
62 //
63 
64 // #define ENABLE_GOEP_L2CAP
65 
66 #ifdef ENABLE_GOEP_L2CAP
67 #ifndef ENABLE_L2CAP_ENHANCED_RETRANSMISSION_MODE
68 #error "ENABLE_GOEP_L2CAP requires ENABLE_L2CAP_ENHANCED_RETRANSMISSION_MODE. Please enable ENABLE_L2CAP_ENHANCED_RETRANSMISSION_MODE or disable ENABLE_GOEP_L2CAP"
69 #endif
70 #endif
71 
72 typedef enum {
73     GOEP_INIT,
74     GOEP_W4_SDP,
75     GOEP_W4_CONNECTION,
76     GOEP_CONNECTED,
77 } goep_state_t;
78 
79 typedef struct {
80     uint16_t         cid;
81     goep_state_t     state;
82     bd_addr_t        bd_addr;
83     hci_con_handle_t con_handle;
84     uint8_t          incoming;
85     uint8_t          rfcomm_port;
86     uint16_t         l2cap_psm;
87     uint16_t         bearer_cid;
88     uint16_t         bearer_mtu;
89     uint32_t         pbap_supported_features;
90 
91     uint8_t          obex_opcode;
92     uint32_t         obex_connection_id;
93     int              obex_connection_id_set;
94 
95     btstack_packet_handler_t client_handler;
96 } goep_client_t;
97 
98 static goep_client_t _goep_client;
99 static goep_client_t * goep_client = &_goep_client;
100 
101 static uint8_t            attribute_value[30];
102 static const unsigned int attribute_value_buffer_size = sizeof(attribute_value);
103 
104 static uint8_t goep_packet_buffer[100];
105 
106 #ifdef ENABLE_GOEP_L2CAP
107 static uint8_t ertm_buffer[1000];
108 static l2cap_ertm_config_t ertm_config = {
109     1,  // ertm mandatory
110     2,  // max transmit, some tests require > 1
111     2000,
112     12000,
113     512,    // l2cap ertm mtu
114     2,
115     2,
116     0,      // No FCS
117 };
118 #endif
119 
120 static inline void goep_client_emit_connected_event(goep_client_t * context, uint8_t status){
121     uint8_t event[15];
122     int pos = 0;
123     event[pos++] = HCI_EVENT_GOEP_META;
124     pos++;  // skip len
125     event[pos++] = GOEP_SUBEVENT_CONNECTION_OPENED;
126     little_endian_store_16(event,pos,context->cid);
127     pos+=2;
128     event[pos++] = status;
129     memcpy(&event[pos], context->bd_addr, 6);
130     pos += 6;
131     little_endian_store_16(event,pos,context->con_handle);
132     pos += 2;
133     event[pos++] = context->incoming;
134     event[1] = pos - 2;
135     if (pos != sizeof(event)) log_error("goep_client_emit_connected_event size %u", pos);
136     context->client_handler(HCI_EVENT_PACKET, context->cid, &event[0], pos);
137 }
138 
139 static inline void goep_client_emit_connection_closed_event(goep_client_t * context){
140     uint8_t event[5];
141     int pos = 0;
142     event[pos++] = HCI_EVENT_GOEP_META;
143     pos++;  // skip len
144     event[pos++] = GOEP_SUBEVENT_CONNECTION_CLOSED;
145     little_endian_store_16(event,pos,context->cid);
146     pos+=2;
147     event[1] = pos - 2;
148     if (pos != sizeof(event)) log_error("goep_client_emit_connection_closed_event size %u", pos);
149     context->client_handler(HCI_EVENT_PACKET, context->cid, &event[0], pos);
150 }
151 
152 static inline void goep_client_emit_can_send_now_event(goep_client_t * context){
153     uint8_t event[5];
154     int pos = 0;
155     event[pos++] = HCI_EVENT_GOEP_META;
156     pos++;  // skip len
157     event[pos++] = GOEP_SUBEVENT_CAN_SEND_NOW;
158     little_endian_store_16(event,pos,context->cid);
159     pos+=2;
160     event[1] = pos - 2;
161     if (pos != sizeof(event)) log_error("goep_client_emit_can_send_now_event size %u", pos);
162     context->client_handler(HCI_EVENT_PACKET, context->cid, &event[0], pos);
163 }
164 
165 static void goep_client_handle_connection_opened(goep_client_t * context, uint8_t status, uint16_t mtu){
166     if (status) {
167         context->state = GOEP_INIT;
168         log_info("goep_client: open failed, status %u", status);
169     } else {
170         context->bearer_mtu = mtu;
171         context->state = GOEP_CONNECTED;
172         log_info("goep_client: connection opened. cid %u, max frame size %u", context->bearer_cid, context->bearer_mtu);
173     }
174     goep_client_emit_connected_event(context, status);
175 }
176 
177 static void goep_client_handle_connection_close(goep_client_t * context){
178     context->state = GOEP_INIT;
179     goep_client_emit_connection_closed_event(context);
180 }
181 
182 static void goep_client_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
183     UNUSED(channel);
184     UNUSED(size);
185     goep_client_t * context = goep_client;
186     switch (packet_type){
187         case HCI_EVENT_PACKET:
188             switch (hci_event_packet_get_type(packet)) {
189 #ifdef ENABLE_GOEP_L2CAP
190                 case L2CAP_EVENT_CHANNEL_OPENED:
191                     goep_client_handle_connection_opened(context, l2cap_event_channel_opened_get_status(packet),
192                         btstack_min(l2cap_event_channel_opened_get_remote_mtu(packet), l2cap_event_channel_opened_get_local_mtu(packet)));
193                     return;
194                 case L2CAP_EVENT_CAN_SEND_NOW:
195                     goep_client_emit_can_send_now_event(context);
196                     break;
197                 case L2CAP_EVENT_CHANNEL_CLOSED:
198                     goep_client_handle_connection_close(context);
199                     break;
200 #endif
201                 case RFCOMM_EVENT_CHANNEL_OPENED:
202                     goep_client_handle_connection_opened(context, rfcomm_event_channel_opened_get_status(packet), rfcomm_event_channel_opened_get_max_frame_size(packet));
203                     return;
204                 case RFCOMM_EVENT_CAN_SEND_NOW:
205                     goep_client_emit_can_send_now_event(context);
206                     break;
207                 case RFCOMM_EVENT_CHANNEL_CLOSED:
208                     goep_client_handle_connection_close(context);
209                     break;
210                 default:
211                     break;
212             }
213             break;
214         case L2CAP_DATA_PACKET:
215         case RFCOMM_DATA_PACKET:
216             context->client_handler(GOEP_DATA_PACKET, context->cid, packet, size);
217             break;
218         default:
219             break;
220     }
221 }
222 
223 static void goep_client_handle_sdp_query_event(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
224     goep_client_t * context = goep_client;
225 
226     UNUSED(packet_type);
227     UNUSED(channel);
228     UNUSED(size);
229 
230     des_iterator_t des_list_it;
231     des_iterator_t prot_it;
232     uint8_t status;
233 
234 
235     switch (hci_event_packet_get_type(packet)){
236         case SDP_EVENT_QUERY_ATTRIBUTE_VALUE:
237 
238             // check if relevant attribute
239             switch(sdp_event_query_attribute_byte_get_attribute_id(packet)){
240                 case BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST:
241                 case BLUETOOTH_ATTRIBUTE_PBAP_SUPPORTED_FEATURES:
242 #ifdef ENABLE_GOEP_L2CAP
243                 case BLUETOOTH_ATTRIBUTE_GOEP_L2CAP_PSM:
244 #endif
245                     break;
246                 default:
247                     return;
248             }
249 
250             // warn if attribute too large to fit in our buffer
251             if (sdp_event_query_attribute_byte_get_attribute_length(packet) > attribute_value_buffer_size) {
252                 log_error("SDP attribute value size exceeded for attribute %x: available %d, required %d", sdp_event_query_attribute_byte_get_attribute_id(packet), attribute_value_buffer_size, sdp_event_query_attribute_byte_get_attribute_length(packet));
253                 break;
254             }
255 
256             // store single byte
257             attribute_value[sdp_event_query_attribute_byte_get_data_offset(packet)] = sdp_event_query_attribute_byte_get_data(packet);
258 
259             // wait until value fully received
260             if ((uint16_t)(sdp_event_query_attribute_byte_get_data_offset(packet)+1) != sdp_event_query_attribute_byte_get_attribute_length(packet)) break;
261 
262             // process attributes
263             switch(sdp_event_query_attribute_byte_get_attribute_id(packet)) {
264                 case BLUETOOTH_ATTRIBUTE_PROTOCOL_DESCRIPTOR_LIST:
265                     for (des_iterator_init(&des_list_it, attribute_value); des_iterator_has_more(&des_list_it); des_iterator_next(&des_list_it)) {
266                         uint8_t       *des_element;
267                         uint8_t       *element;
268                         uint32_t       uuid;
269 #ifdef ENABLE_GOEP_L2CAP
270                         uint16_t       l2cap_psm;
271 #endif
272 
273                         if (des_iterator_get_type(&des_list_it) != DE_DES) continue;
274 
275                         des_element = des_iterator_get_element(&des_list_it);
276                         des_iterator_init(&prot_it, des_element);
277 
278                         // first element is UUID
279                         element = des_iterator_get_element(&prot_it);
280                         if (de_get_element_type(element) != DE_UUID) continue;
281 
282                         uuid = de_get_uuid32(element);
283                         des_iterator_next(&prot_it);
284                         if (!des_iterator_has_more(&prot_it)) continue;
285 
286                         // second element is RFCOMM server channel or L2CAP PSM
287                         element = des_iterator_get_element(&prot_it);
288                         switch (uuid){
289 #ifdef ENABLE_GOEP_L2CAP
290                             case BLUETOOTH_PROTOCOL_L2CAP:
291                                 if (de_element_get_uint16(element, &l2cap_psm)){
292                                     context->l2cap_psm = l2cap_psm;
293                                 }
294                                 break;
295 #endif
296                             case BLUETOOTH_PROTOCOL_RFCOMM:
297                                 context->rfcomm_port = element[de_get_header_size(element)];
298                                 break;
299                             default:
300                                 break;
301                         }
302                     }
303                     break;
304 #ifdef ENABLE_GOEP_L2CAP
305                 case BLUETOOTH_ATTRIBUTE_GOEP_L2CAP_PSM:
306                     de_element_get_uint16(attribute_value, &context->l2cap_psm);
307                     break;
308 #endif
309                 case BLUETOOTH_ATTRIBUTE_PBAP_SUPPORTED_FEATURES:
310                     if (de_get_element_type(attribute_value) != DE_UINT) break;
311                     if (de_get_size_type(attribute_value)    != DE_SIZE_32) break;
312                     context->pbap_supported_features  = big_endian_read_32(attribute_value, de_get_header_size(attribute_value));
313                     log_info("pbap_supported_features 0x%x", context->pbap_supported_features);
314                     break;
315                 default:
316                     break;
317             }
318             break;
319 
320         case SDP_EVENT_QUERY_COMPLETE:
321             status = sdp_event_query_complete_get_status(packet);
322             if (status != ERROR_CODE_SUCCESS){
323                 log_info("GOEP client, SDP query failed 0x%02x", status);
324                 context->state = GOEP_INIT;
325                 goep_client_emit_connected_event(goep_client, status);
326                 break;
327             }
328             if ((context->rfcomm_port == 0) && (context->l2cap_psm == 0)){
329                 log_info("No GOEP RFCOMM or L2CAP server found");
330                 context->state = GOEP_INIT;
331                 goep_client_emit_connected_event(goep_client, ERROR_CODE_UNSUPPORTED_FEATURE_OR_PARAMETER_VALUE);
332                 break;
333             }
334 #ifdef ENABLE_GOEP_L2CAP
335             if (context->l2cap_psm){
336                 log_info("Remote GOEP L2CAP PSM: %u", context->l2cap_psm);
337                 l2cap_create_ertm_channel(&goep_client_packet_handler, context->bd_addr, context->l2cap_psm,
338                                           &ertm_config, ertm_buffer, sizeof(ertm_buffer), &context->bearer_cid);
339                 return;
340             }
341 #endif
342             log_info("Remote GOEP RFCOMM Server Channel: %u", context->rfcomm_port);
343             rfcomm_create_channel(&goep_client_packet_handler, context->bd_addr, context->rfcomm_port, &context->bearer_cid);
344     }
345 }
346 
347 static uint8_t * goep_client_get_outgoing_buffer(goep_client_t * context){
348     if (context->l2cap_psm){
349         return goep_packet_buffer;
350     } else {
351         return rfcomm_get_outgoing_buffer();
352     }
353 }
354 
355 static uint16_t goep_client_get_outgoing_buffer_len(goep_client_t * context){
356     if (context->l2cap_psm){
357         return sizeof(goep_packet_buffer);
358     } else {
359         return rfcomm_get_max_frame_size(context->bearer_cid);
360     }
361 }
362 
363 static void goep_client_packet_init(uint16_t goep_cid, uint8_t opcode){
364     UNUSED(goep_cid);
365     goep_client_t * context = goep_client;
366     if (context->l2cap_psm){
367     } else {
368         rfcomm_reserve_packet_buffer();
369     }
370     // store opcode for parsing of response
371     context->obex_opcode = opcode;
372 }
373 
374 void goep_client_init(void){
375     memset(goep_client, 0, sizeof(goep_client_t));
376     goep_client->state = GOEP_INIT;
377     goep_client->cid = 1;
378     goep_client->obex_connection_id = OBEX_CONNECTION_ID_INVALID;
379 }
380 
381 uint8_t goep_client_create_connection(btstack_packet_handler_t handler, bd_addr_t addr, uint16_t uuid, uint16_t * out_cid){
382     goep_client_t * context = goep_client;
383     if (context->state != GOEP_INIT) return BTSTACK_MEMORY_ALLOC_FAILED;
384     context->client_handler = handler;
385     context->state = GOEP_W4_SDP;
386     context->l2cap_psm   = 0;
387     context->rfcomm_port = 0;
388     context->pbap_supported_features = PBAP_FEATURES_NOT_PRESENT;
389     memcpy(context->bd_addr, addr, 6);
390     sdp_client_query_uuid16(&goep_client_handle_sdp_query_event, context->bd_addr, uuid);
391     *out_cid = context->cid;
392     return 0;
393 }
394 
395 uint32_t goep_client_get_pbap_supported_features(uint16_t goep_cid){
396     UNUSED(goep_cid);
397     goep_client_t * context = goep_client;
398     return context->pbap_supported_features;
399 }
400 
401 uint8_t goep_client_disconnect(uint16_t goep_cid){
402     UNUSED(goep_cid);
403     goep_client_t * context = goep_client;
404     rfcomm_disconnect(context->bearer_cid);
405     return 0;
406 }
407 
408 void goep_client_set_connection_id(uint16_t goep_cid, uint32_t connection_id){
409     UNUSED(goep_cid);
410     goep_client_t * context = goep_client;
411     context->obex_connection_id = connection_id;
412 }
413 
414 uint8_t goep_client_get_request_opcode(uint16_t goep_cid){
415     UNUSED(goep_cid);
416     goep_client_t * context = goep_client;
417     return context->obex_opcode;
418 }
419 
420 void goep_client_request_can_send_now(uint16_t goep_cid){
421     UNUSED(goep_cid);
422     goep_client_t * context = goep_client;
423     if (context->l2cap_psm){
424         l2cap_request_can_send_now_event(context->bearer_cid);
425     } else {
426         rfcomm_request_can_send_now_event(context->bearer_cid);
427     }
428 }
429 
430 void goep_client_request_create_connect(uint16_t goep_cid, uint8_t obex_version_number, uint8_t flags, uint16_t maximum_obex_packet_length){
431     UNUSED(goep_cid);
432     goep_client_t * context = goep_client;
433     goep_client_packet_init(goep_cid, OBEX_OPCODE_CONNECT);
434 
435     // workaround: limit OBEX packet len to L2CAP/RFCOMM MTU to avoid handling of fragemented packets
436     maximum_obex_packet_length = btstack_min(maximum_obex_packet_length, context->bearer_mtu);
437 
438     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
439     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
440     obex_message_builder_request_create_connect(buffer, buffer_len, obex_version_number, flags, maximum_obex_packet_length);
441 }
442 
443 void goep_client_request_create_get(uint16_t goep_cid){
444     UNUSED(goep_cid);
445     goep_client_t * context = goep_client;
446     goep_client_packet_init(goep_cid, OBEX_OPCODE_GET | OBEX_OPCODE_FINAL_BIT_MASK);
447 
448     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
449     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
450     obex_message_builder_request_create_get(buffer, buffer_len, context->obex_connection_id);
451 }
452 
453 void goep_client_request_create_put(uint16_t goep_cid){
454     UNUSED(goep_cid);
455     goep_client_t * context = goep_client;
456     goep_client_packet_init(goep_cid, OBEX_OPCODE_PUT | OBEX_OPCODE_FINAL_BIT_MASK);
457 
458     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
459     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
460     obex_message_builder_request_create_put(buffer, buffer_len, context->obex_connection_id);
461 }
462 
463 void goep_client_request_create_set_path(uint16_t goep_cid, uint8_t flags){
464     UNUSED(goep_cid);
465     goep_client_t * context = goep_client;
466     goep_client_packet_init(goep_cid, OBEX_OPCODE_SETPATH);
467 
468     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
469     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
470     obex_message_builder_request_create_set_path(buffer, buffer_len, flags, context->obex_connection_id);
471 }
472 
473 void goep_client_request_create_abort(uint16_t goep_cid){
474     UNUSED(goep_cid);
475     goep_client_t * context = goep_client;
476     goep_client_packet_init(goep_cid, OBEX_OPCODE_ABORT);
477 
478     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
479     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
480     obex_message_builder_request_create_abort(buffer, buffer_len, context->obex_connection_id);
481 }
482 
483 void goep_client_request_create_disconnect(uint16_t goep_cid){
484     UNUSED(goep_cid);
485     goep_client_t * context = goep_client;
486     goep_client_packet_init(goep_cid, OBEX_OPCODE_DISCONNECT);
487 
488     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
489     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
490     obex_message_builder_request_create_disconnect(buffer, buffer_len, context->obex_connection_id);
491 }
492 
493 void goep_client_header_add_byte(uint16_t goep_cid, uint8_t header_type, uint8_t value){
494     UNUSED(goep_cid);
495     goep_client_t * context = goep_client;
496 
497     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
498     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
499     obex_message_builder_header_add_byte(buffer, buffer_len, header_type, value);
500 }
501 
502 void goep_client_header_add_word(uint16_t goep_cid, uint8_t header_type, uint32_t value){
503     UNUSED(goep_cid);
504     goep_client_t * context = goep_client;
505 
506     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
507     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
508     obex_message_builder_header_add_word(buffer, buffer_len, header_type, value);
509 }
510 
511 void goep_client_header_add_variable(uint16_t goep_cid, uint8_t header_type, const uint8_t * header_data, uint16_t header_data_length){
512     UNUSED(goep_cid);
513     goep_client_t * context = goep_client;
514 
515     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
516     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
517     obex_message_builder_header_add_variable(buffer, buffer_len, header_type, header_data, header_data_length);
518 }
519 
520 void goep_client_header_add_srm_enable(uint16_t goep_cid){
521     UNUSED(goep_cid);
522     goep_client_t * context = goep_client;
523 
524     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
525     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
526     obex_message_builder_header_add_srm_enable(buffer, buffer_len);
527 }
528 
529 void goep_client_header_add_target(uint16_t goep_cid, const uint8_t * target, uint16_t length){
530     UNUSED(goep_cid);
531     goep_client_t * context = goep_client;
532 
533     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
534     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
535     obex_message_builder_header_add_target(buffer, buffer_len, target, length);
536 }
537 
538 void goep_client_header_add_application_parameters(uint16_t goep_cid, const uint8_t * data, uint16_t length){
539     UNUSED(goep_cid);
540     goep_client_t * context = goep_client;
541 
542     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
543     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
544     obex_message_builder_header_add_application_parameters(buffer, buffer_len, data, length);
545 }
546 
547 void goep_client_header_add_challenge_response(uint16_t goep_cid, const uint8_t * data, uint16_t length){
548     UNUSED(goep_cid);
549     goep_client_t * context = goep_client;
550 
551     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
552     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
553     obex_message_builder_header_add_challenge_response(buffer, buffer_len, data, length);
554 }
555 
556 void goep_client_body_add_static(uint16_t goep_cid, const uint8_t * data, uint32_t length){
557     UNUSED(goep_cid);
558     goep_client_t * context = goep_client;
559 
560     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
561     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
562     obex_message_builder_body_add_static(buffer, buffer_len, data, length);
563 }
564 
565 void goep_client_header_add_name(uint16_t goep_cid, const char * name){
566     UNUSED(goep_cid);
567     goep_client_t * context = goep_client;
568 
569     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
570     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
571     obex_message_builder_header_add_name(buffer, buffer_len, name);
572 }
573 
574 void goep_client_header_add_type(uint16_t goep_cid, const char * type){
575     UNUSED(goep_cid);
576     goep_client_t * context = goep_client;
577 
578     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
579     uint16_t buffer_len = goep_client_get_outgoing_buffer_len(context);
580     obex_message_builder_header_add_type(buffer, buffer_len, type);
581 }
582 
583 int goep_client_execute(uint16_t goep_cid){
584     UNUSED(goep_cid);
585     goep_client_t * context = goep_client;
586     uint8_t * buffer = goep_client_get_outgoing_buffer(context);
587     uint16_t pos = big_endian_read_16(buffer, 1);
588     if (context->l2cap_psm){
589         return l2cap_send(context->bearer_cid, buffer, pos);
590     } else {
591         return rfcomm_send_prepared(context->bearer_cid, pos);
592     }
593 }
594 
595