xref: /btstack/src/classic/sdp_server.c (revision ced70f9bfeafe291ec597a3a9cc862e39e0da3ce)
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 BLUEKITCHEN
24  * GMBH 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__ "sdp_server.c"
39 
40 /*
41  * Implementation of the Service Discovery Protocol Server
42  */
43 
44 #include <string.h>
45 
46 #include "bluetooth.h"
47 #include "bluetooth_psm.h"
48 #include "bluetooth_sdp.h"
49 #include "btstack_debug.h"
50 #include "btstack_event.h"
51 #include "btstack_memory.h"
52 #include "classic/core.h"
53 #include "classic/sdp_server.h"
54 #include "classic/sdp_util.h"
55 #include "hci.h"
56 #include "hci_dump.h"
57 #include "l2cap.h"
58 
59 // max number of incoming l2cap connections that can be queued instead of getting rejected
60 #ifndef SDP_WAITING_LIST_MAX_COUNT
61 #define SDP_WAITING_LIST_MAX_COUNT 8
62 #endif
63 
64 // max reserved ServiceRecordHandle
65 #define MAX_RESERVED_SERVICE_RECORD_HANDLE 0xffff
66 
67 // max SDP response matches L2CAP PDU -- allow to use smaller buffer
68 #ifndef SDP_RESPONSE_BUFFER_SIZE
69 #define SDP_RESPONSE_BUFFER_SIZE (HCI_ACL_PAYLOAD_SIZE-L2CAP_HEADER_SIZE)
70 #endif
71 
72 static void sdp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
73 
74 // registered service records
75 static btstack_linked_list_t sdp_server_service_records;
76 
77 // our handles start after the reserved range
78 static uint32_t sdp_server_next_service_record_handle;
79 
80 static uint8_t sdp_response_buffer[SDP_RESPONSE_BUFFER_SIZE];
81 
82 static uint16_t sdp_server_l2cap_cid;
83 static uint16_t sdp_server_response_size;
84 static uint16_t sdp_server_l2cap_waiting_list_cids[SDP_WAITING_LIST_MAX_COUNT];
85 static int      sdp_server_l2cap_waiting_list_count;
86 
87 void sdp_init(void){
88     sdp_server_next_service_record_handle = ((uint32_t) MAX_RESERVED_SERVICE_RECORD_HANDLE) + 2;
89     // register with l2cap psm sevices - max MTU
90     l2cap_register_service(sdp_packet_handler, BLUETOOTH_PSM_SDP, 0xffff, LEVEL_0);
91 }
92 
93 void sdp_deinit(void){
94     sdp_server_service_records = NULL;
95     sdp_server_l2cap_cid = 0;
96     sdp_server_response_size = 0;
97     sdp_server_l2cap_waiting_list_count = 0;
98 }
99 
100 uint32_t sdp_get_service_record_handle(const uint8_t * record){
101     // TODO: make sdp_get_attribute_value_for_attribute_id accept const data to remove cast
102     uint8_t * serviceRecordHandleAttribute = sdp_get_attribute_value_for_attribute_id((uint8_t *)record, BLUETOOTH_ATTRIBUTE_SERVICE_RECORD_HANDLE);
103     if (!serviceRecordHandleAttribute) return 0;
104     if (de_get_element_type(serviceRecordHandleAttribute) != DE_UINT) return 0;
105     if (de_get_size_type(serviceRecordHandleAttribute) != DE_SIZE_32) return 0;
106     return big_endian_read_32(serviceRecordHandleAttribute, 1);
107 }
108 
109 static service_record_item_t * sdp_get_record_item_for_handle(uint32_t handle){
110     btstack_linked_item_t *it;
111     for (it = (btstack_linked_item_t *) sdp_server_service_records; it ; it = it->next){
112         service_record_item_t * item = (service_record_item_t *) it;
113         if (item->service_record_handle == handle){
114             return item;
115         }
116     }
117     return NULL;
118 }
119 
120 uint8_t * sdp_get_record_for_handle(uint32_t handle){
121     service_record_item_t * record_item =  sdp_get_record_item_for_handle(handle);
122     if (!record_item) return NULL;
123     return record_item->service_record;
124 }
125 
126 // get next free, unregistered service record handle
127 uint32_t sdp_create_service_record_handle(void){
128     uint32_t handle = 0;
129     do {
130         handle = sdp_server_next_service_record_handle++;
131         if (sdp_get_record_item_for_handle(handle)) handle = 0;
132     } while (handle == 0);
133     return handle;
134 }
135 
136 /**
137  * @brief Register Service Record with database using ServiceRecordHandle stored in record
138  * @pre AttributeIDs are in ascending order
139  * @pre ServiceRecordHandle is first attribute and valid
140  * @param record is not copied!
141  * @result status
142  */
143 uint8_t sdp_register_service(const uint8_t * record){
144 
145     // validate service record handle. it must: exist, be in valid range, not have been already used
146     uint32_t record_handle = sdp_get_service_record_handle(record);
147     if (!record_handle) return SDP_HANDLE_INVALID;
148     if (record_handle <= MAX_RESERVED_SERVICE_RECORD_HANDLE) return SDP_HANDLE_INVALID;
149     if (sdp_get_record_item_for_handle(record_handle)) return SDP_HANDLE_ALREADY_REGISTERED;
150 
151     // alloc memory for new service_record_item
152     service_record_item_t * newRecordItem = btstack_memory_service_record_item_get();
153     if (!newRecordItem) return BTSTACK_MEMORY_ALLOC_FAILED;
154 
155     // set handle and record
156     newRecordItem->service_record_handle = record_handle;
157     newRecordItem->service_record = (uint8_t*) record;
158 
159     // add to linked list
160     btstack_linked_list_add(&sdp_server_service_records, (btstack_linked_item_t *) newRecordItem);
161 
162     return 0;
163 }
164 
165 //
166 // unregister service record
167 //
168 void sdp_unregister_service(uint32_t service_record_handle){
169     service_record_item_t * record_item = sdp_get_record_item_for_handle(service_record_handle);
170     if (!record_item) return;
171     btstack_linked_list_remove(&sdp_server_service_records, (btstack_linked_item_t *) record_item);
172     btstack_memory_service_record_item_free(record_item);
173 }
174 
175 // PDU
176 // PDU ID (1), Transaction ID (2), Param Length (2), Param 1, Param 2, ..
177 
178 static int sdp_create_error_response(uint16_t transaction_id, uint16_t error_code){
179     sdp_response_buffer[0] = SDP_ErrorResponse;
180     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
181     big_endian_store_16(sdp_response_buffer, 3, 2);
182     big_endian_store_16(sdp_response_buffer, 5, error_code); // invalid syntax
183     return 7;
184 }
185 
186 int sdp_handle_service_search_request(uint8_t * packet, uint16_t remote_mtu){
187 
188     // get request details
189     uint16_t  transaction_id = big_endian_read_16(packet, 1);
190     uint16_t  param_len = big_endian_read_16(packet, 3);
191     uint8_t * serviceSearchPattern = &packet[5];
192     uint16_t  serviceSearchPatternLen = de_get_len_safe(serviceSearchPattern, param_len);
193     // assert service search pattern is contained
194     if (!serviceSearchPatternLen) return 0;
195     param_len -= serviceSearchPatternLen;
196     // assert max record count is contained
197     if (param_len < 2) return 0;
198     uint16_t  maximumServiceRecordCount = big_endian_read_16(packet, 5 + serviceSearchPatternLen);
199     param_len -= 2;
200     // assert continuation state len is contained in param_len
201     if (param_len < 1) return 0;
202     uint8_t * continuationState = &packet[5+serviceSearchPatternLen+2];
203     // assert continuation state is contained in param_len
204     if ((1 + continuationState[0]) > param_len) return 0;
205 
206     // calc maximumServiceRecordCount based on remote MTU
207     uint16_t maxNrServiceRecordsPerResponse = (remote_mtu - (9+3))/4;
208 
209     // continuation state contains index of next service record to examine
210     int      continuation = 0;
211     uint16_t continuation_index = 0;
212     if (continuationState[0] == 2){
213         continuation_index = big_endian_read_16(continuationState, 1);
214     }
215 
216     // get and limit total count
217     btstack_linked_item_t *it;
218     uint16_t total_service_count   = 0;
219     for (it = (btstack_linked_item_t *) sdp_server_service_records; it ; it = it->next){
220         service_record_item_t * item = (service_record_item_t *) it;
221         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
222         total_service_count++;
223     }
224     if (total_service_count > maximumServiceRecordCount){
225         total_service_count = maximumServiceRecordCount;
226     }
227 
228     // ServiceRecordHandleList at 9
229     uint16_t pos = 9;
230     uint16_t current_service_count  = 0;
231     uint16_t current_service_index  = 0;
232     uint16_t matching_service_count = 0;
233     for (it = (btstack_linked_item_t *) sdp_server_service_records; it ; it = it->next, ++current_service_index){
234         service_record_item_t * item = (service_record_item_t *) it;
235 
236         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
237         matching_service_count++;
238 
239         if (current_service_index < continuation_index) continue;
240 
241         big_endian_store_32(sdp_response_buffer, pos, item->service_record_handle);
242         pos += 4;
243         current_service_count++;
244 
245         if (matching_service_count >= total_service_count) break;
246 
247         if (current_service_count >= maxNrServiceRecordsPerResponse){
248             continuation = 1;
249             continuation_index = current_service_index + 1;
250             break;
251         }
252     }
253 
254     // Store continuation state
255     if (continuation) {
256         sdp_response_buffer[pos++] = 2;
257         big_endian_store_16(sdp_response_buffer, pos, continuation_index);
258         pos += 2;
259     } else {
260         sdp_response_buffer[pos++] = 0;
261     }
262 
263     // header
264     sdp_response_buffer[0] = SDP_ServiceSearchResponse;
265     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
266     big_endian_store_16(sdp_response_buffer, 3, pos - 5); // size of variable payload
267     big_endian_store_16(sdp_response_buffer, 5, total_service_count);
268     big_endian_store_16(sdp_response_buffer, 7, current_service_count);
269 
270     return pos;
271 }
272 
273 int sdp_handle_service_attribute_request(uint8_t * packet, uint16_t remote_mtu){
274 
275     // get request details
276     uint16_t  transaction_id = big_endian_read_16(packet, 1);
277     uint16_t  param_len = big_endian_read_16(packet, 3);
278     // assert serviceRecordHandle and maximumAttributeByteCount are in param_len
279     if (param_len < 6) return 0;
280     uint32_t  serviceRecordHandle = big_endian_read_32(packet, 5);
281     uint16_t  maximumAttributeByteCount = big_endian_read_16(packet, 9);
282     param_len -= 6;
283     uint8_t * attributeIDList = &packet[11];
284     uint16_t  attributeIDListLen = de_get_len_safe(attributeIDList, param_len);
285     // assert attributeIDList are in param_len
286     if (!attributeIDListLen) return 0;
287     param_len -= attributeIDListLen;
288     // assert continuation state len is contained in param_len
289     if (param_len < 1) return 0;
290     uint8_t * continuationState = &packet[11+attributeIDListLen];
291     // assert continuation state is contained in param_len
292     if ((1 + continuationState[0]) > param_len) return 0;
293 
294     // calc maximumAttributeByteCount based on remote MTU
295     uint16_t maximumAttributeByteCount2 = remote_mtu - (7+3);
296     if (maximumAttributeByteCount2 < maximumAttributeByteCount) {
297         maximumAttributeByteCount = maximumAttributeByteCount2;
298     }
299 
300     // continuation state contains the offset into the complete response
301     uint16_t continuation_offset = 0;
302     if (continuationState[0] == 2){
303         continuation_offset = big_endian_read_16(continuationState, 1);
304     }
305 
306     // get service record
307     service_record_item_t * item = sdp_get_record_item_for_handle(serviceRecordHandle);
308     if (!item){
309         // service record handle doesn't exist
310         return sdp_create_error_response(transaction_id, 0x0002); /// invalid Service Record Handle
311     }
312 
313 
314     // AttributeList - starts at offset 7
315     uint16_t pos = 7;
316 
317     if (continuation_offset == 0){
318 
319         // get size of this record
320         uint16_t filtered_attributes_size = sdp_get_filtered_size(item->service_record, attributeIDList);
321 
322         // store DES
323         de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, filtered_attributes_size);
324         maximumAttributeByteCount -= 3;
325         pos += 3;
326     }
327 
328     // copy maximumAttributeByteCount from record
329     uint16_t bytes_used;
330     int complete = sdp_filter_attributes_in_attributeIDList(item->service_record, attributeIDList, continuation_offset, maximumAttributeByteCount, &bytes_used, &sdp_response_buffer[pos]);
331     pos += bytes_used;
332 
333     uint16_t attributeListByteCount = pos - 7;
334 
335     if (complete) {
336         sdp_response_buffer[pos++] = 0;
337     } else {
338         continuation_offset += bytes_used;
339         sdp_response_buffer[pos++] = 2;
340         big_endian_store_16(sdp_response_buffer, pos, continuation_offset);
341         pos += 2;
342     }
343 
344     // header
345     sdp_response_buffer[0] = SDP_ServiceAttributeResponse;
346     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
347     big_endian_store_16(sdp_response_buffer, 3, pos - 5);  // size of variable payload
348     big_endian_store_16(sdp_response_buffer, 5, attributeListByteCount);
349 
350     return pos;
351 }
352 
353 static uint16_t sdp_get_size_for_service_search_attribute_response(uint8_t * serviceSearchPattern, uint8_t * attributeIDList){
354     uint16_t total_response_size = 0;
355     btstack_linked_item_t *it;
356     for (it = (btstack_linked_item_t *) sdp_server_service_records; it ; it = it->next){
357         service_record_item_t * item = (service_record_item_t *) it;
358 
359         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
360 
361         // for all service records that match
362         total_response_size += 3 + sdp_get_filtered_size(item->service_record, attributeIDList);
363     }
364     return total_response_size;
365 }
366 
367 int sdp_handle_service_search_attribute_request(uint8_t * packet, uint16_t remote_mtu){
368 
369     // SDP header before attribute sevice list: 7
370     // Continuation, worst case: 5
371 
372     // get request details
373     uint16_t  transaction_id = big_endian_read_16(packet, 1);
374     uint16_t  param_len = big_endian_read_16(packet, 3);
375     uint8_t * serviceSearchPattern = &packet[5];
376     uint16_t  serviceSearchPatternLen = de_get_len_safe(serviceSearchPattern, param_len);
377     // assert serviceSearchPattern header is contained in param_len
378     if (!serviceSearchPatternLen) return 0;
379     param_len -= serviceSearchPatternLen;
380     // assert maximumAttributeByteCount contained in param_len
381     if (param_len < 2) return 0;
382     uint16_t  maximumAttributeByteCount = big_endian_read_16(packet, 5 + serviceSearchPatternLen);
383     param_len -= 2;
384     uint8_t * attributeIDList = &packet[5+serviceSearchPatternLen+2];
385     uint16_t  attributeIDListLen = de_get_len_safe(attributeIDList, param_len);
386     // assert attributeIDList is contained in param_len
387     if (!attributeIDListLen) return 0;
388     // assert continuation state len is contained in param_len
389     if (param_len < 1) return 0;
390     uint8_t * continuationState = &packet[5+serviceSearchPatternLen+2+attributeIDListLen];
391     // assert continuation state is contained in param_len
392     if ((1 + continuationState[0]) > param_len) return 0;
393 
394     // calc maximumAttributeByteCount based on remote MTU, SDP header and reserved Continuation block
395     uint16_t maximumAttributeByteCount2 = remote_mtu - 12;
396     if (maximumAttributeByteCount2 < maximumAttributeByteCount) {
397         maximumAttributeByteCount = maximumAttributeByteCount2;
398     }
399 
400     // continuation state contains: index of next service record to examine
401     // continuation state contains: byte offset into this service record
402     uint16_t continuation_service_index = 0;
403     uint16_t continuation_offset = 0;
404     if (continuationState[0] == 4){
405         continuation_service_index = big_endian_read_16(continuationState, 1);
406         continuation_offset = big_endian_read_16(continuationState, 3);
407     }
408 
409     // log_info("--> sdp_handle_service_search_attribute_request, cont %u/%u, max %u", continuation_service_index, continuation_offset, maximumAttributeByteCount);
410 
411     // AttributeLists - starts at offset 7
412     uint16_t pos = 7;
413 
414     // add DES with total size for first request
415     if ((continuation_service_index == 0) && (continuation_offset == 0)){
416         uint16_t total_response_size = sdp_get_size_for_service_search_attribute_response(serviceSearchPattern, attributeIDList);
417         de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, total_response_size);
418         // log_info("total response size %u", total_response_size);
419         pos += 3;
420         maximumAttributeByteCount -= 3;
421     }
422 
423     // create attribute list
424     int      first_answer = 1;
425     int      continuation = 0;
426     uint16_t current_service_index = 0;
427     btstack_linked_item_t *it = (btstack_linked_item_t *) sdp_server_service_records;
428     for ( ; it ; it = it->next, ++current_service_index){
429         service_record_item_t * item = (service_record_item_t *) it;
430 
431         if (current_service_index < continuation_service_index ) continue;
432         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
433 
434         if (continuation_offset == 0){
435 
436             // get size of this record
437             uint16_t filtered_attributes_size = sdp_get_filtered_size(item->service_record, attributeIDList);
438 
439             // stop if complete record doesn't fits into response but we already have a partial response
440             if (((filtered_attributes_size + 3) > maximumAttributeByteCount) && !first_answer) {
441                 continuation = 1;
442                 break;
443             }
444 
445             // store DES
446             de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, filtered_attributes_size);
447             pos += 3;
448             maximumAttributeByteCount -= 3;
449         }
450 
451         first_answer = 0;
452 
453         // copy maximumAttributeByteCount from record
454         uint16_t bytes_used;
455         int complete = sdp_filter_attributes_in_attributeIDList(item->service_record, attributeIDList, continuation_offset, maximumAttributeByteCount, &bytes_used, &sdp_response_buffer[pos]);
456         pos += bytes_used;
457         maximumAttributeByteCount -= bytes_used;
458 
459         if (complete) {
460             continuation_offset = 0;
461             continue;
462         }
463 
464         continuation = 1;
465         continuation_offset += bytes_used;
466         break;
467     }
468 
469     uint16_t attributeListsByteCount = pos - 7;
470 
471     // Continuation State
472     if (continuation){
473         sdp_response_buffer[pos++] = 4;
474         big_endian_store_16(sdp_response_buffer, pos, (uint16_t) current_service_index);
475         pos += 2;
476         big_endian_store_16(sdp_response_buffer, pos, continuation_offset);
477         pos += 2;
478     } else {
479         // complete
480         sdp_response_buffer[pos++] = 0;
481     }
482 
483     // create SDP header
484     sdp_response_buffer[0] = SDP_ServiceSearchAttributeResponse;
485     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
486     big_endian_store_16(sdp_response_buffer, 3, pos - 5);  // size of variable payload
487     big_endian_store_16(sdp_response_buffer, 5, attributeListsByteCount);
488 
489     return pos;
490 }
491 
492 static void sdp_respond(void){
493     if (!sdp_server_response_size ) return;
494     if (!sdp_server_l2cap_cid) return;
495 
496     // update state before sending packet (avoid getting called when new l2cap credit gets emitted)
497     uint16_t size = sdp_server_response_size;
498     sdp_server_response_size = 0;
499     l2cap_send(sdp_server_l2cap_cid, sdp_response_buffer, size);
500 }
501 
502 // @pre space in list
503 static void sdp_waiting_list_add(uint16_t cid){
504     sdp_server_l2cap_waiting_list_cids[sdp_server_l2cap_waiting_list_count++] = cid;
505 }
506 
507 // @pre at least one item in list
508 static uint16_t sdp_waiting_list_get(void){
509     uint16_t cid = sdp_server_l2cap_waiting_list_cids[0];
510     sdp_server_l2cap_waiting_list_count--;
511     if (sdp_server_l2cap_waiting_list_count){
512         memmove(&sdp_server_l2cap_waiting_list_cids[0], &sdp_server_l2cap_waiting_list_cids[1], sdp_server_l2cap_waiting_list_count * sizeof(uint16_t));
513     }
514     return cid;
515 }
516 
517 // we assume that we don't get two requests in a row
518 static void sdp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
519 	uint16_t transaction_id;
520     sdp_pdu_id_t pdu_id;
521     uint16_t remote_mtu;
522     uint16_t param_len;
523 
524 	switch (packet_type) {
525 
526 		case L2CAP_DATA_PACKET:
527             pdu_id = (sdp_pdu_id_t) packet[0];
528             transaction_id = big_endian_read_16(packet, 1);
529             param_len = big_endian_read_16(packet, 3);
530             remote_mtu = l2cap_get_remote_mtu_for_local_cid(channel);
531             // account for our buffer
532             if (remote_mtu > SDP_RESPONSE_BUFFER_SIZE){
533                 remote_mtu = SDP_RESPONSE_BUFFER_SIZE;
534             }
535             // validate parm_len against packet size
536             if ((param_len + 5) > size) {
537                 // just clear pdu_id
538                 pdu_id = SDP_ErrorResponse;
539             }
540 
541             // log_info("SDP Request: type %u, transaction id %u, len %u, mtu %u", pdu_id, transaction_id, param_len, remote_mtu);
542             switch (pdu_id){
543 
544                 case SDP_ServiceSearchRequest:
545                     sdp_server_response_size = sdp_handle_service_search_request(packet, remote_mtu);
546                     break;
547 
548                 case SDP_ServiceAttributeRequest:
549                     sdp_server_response_size = sdp_handle_service_attribute_request(packet, remote_mtu);
550                     break;
551 
552                 case SDP_ServiceSearchAttributeRequest:
553                     sdp_server_response_size = sdp_handle_service_search_attribute_request(packet, remote_mtu);
554                     break;
555 
556                 default:
557                     sdp_server_response_size = sdp_create_error_response(transaction_id, 0x0003); // invalid syntax
558                     break;
559             }
560             if (!sdp_server_response_size) break;
561             l2cap_request_can_send_now_event(sdp_server_l2cap_cid);
562 			break;
563 
564 		case HCI_EVENT_PACKET:
565 
566 			switch (hci_event_packet_get_type(packet)) {
567 
568 				case L2CAP_EVENT_INCOMING_CONNECTION:
569                     if (sdp_server_l2cap_cid) {
570                         // try to queue up
571                         if (sdp_server_l2cap_waiting_list_count < SDP_WAITING_LIST_MAX_COUNT){
572                             sdp_waiting_list_add(channel);
573                             log_info("busy, queing incoming cid 0x%04x, now %u waiting", channel, sdp_server_l2cap_waiting_list_count);
574                             break;
575                         }
576 
577                         // CONNECTION REJECTED DUE TO LIMITED RESOURCES
578                         l2cap_decline_connection(channel);
579                         break;
580                     }
581                     // accept
582                     sdp_server_l2cap_cid = channel;
583                     sdp_server_response_size = 0;
584                     l2cap_accept_connection(sdp_server_l2cap_cid);
585 					break;
586 
587                 case L2CAP_EVENT_CHANNEL_OPENED:
588                     if (packet[2]) {
589                         // open failed -> reset
590                         sdp_server_l2cap_cid = 0;
591                     }
592                     break;
593 
594                 case L2CAP_EVENT_CAN_SEND_NOW:
595                     sdp_respond();
596                     break;
597 
598                 case L2CAP_EVENT_CHANNEL_CLOSED:
599                     if (channel == sdp_server_l2cap_cid){
600                         // reset
601                         sdp_server_l2cap_cid = 0;
602 
603                         // other request queued?
604                         if (!sdp_server_l2cap_waiting_list_count) break;
605 
606                         // get first item
607                         sdp_server_l2cap_cid = sdp_waiting_list_get();
608 
609                         log_info("disconnect, accept queued cid 0x%04x, now %u waiting", sdp_server_l2cap_cid, sdp_server_l2cap_waiting_list_count);
610 
611                         // accept connection
612                         sdp_server_response_size = 0;
613                         l2cap_accept_connection(sdp_server_l2cap_cid);
614                     }
615                     break;
616 
617 				default:
618 					// other event
619 					break;
620 			}
621 			break;
622 
623 		default:
624 			// other packet type
625 			break;
626 	}
627 }
628 
629