xref: /btstack/src/classic/sdp_server.c (revision 2b1502cef0720d14335056c604f91f4541b5a25c)
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     if (!sdp_attribute_list_valid(attributeIDList) == false){
286         return sdp_create_error_response(transaction_id, 0x0003); /// invalid request syntax
287     }
288     // assert attributeIDList are in param_len
289     if (!attributeIDListLen) return 0;
290     param_len -= attributeIDListLen;
291     // assert continuation state len is contained in param_len
292     if (param_len < 1) return 0;
293     uint8_t * continuationState = &packet[11+attributeIDListLen];
294     // assert continuation state is contained in param_len
295     if ((1 + continuationState[0]) > param_len) return 0;
296 
297     // calc maximumAttributeByteCount based on remote MTU
298     uint16_t maximumAttributeByteCount2 = remote_mtu - (7+3);
299     if (maximumAttributeByteCount2 < maximumAttributeByteCount) {
300         maximumAttributeByteCount = maximumAttributeByteCount2;
301     }
302 
303     // continuation state contains the offset into the complete response
304     uint16_t continuation_offset = 0;
305     if (continuationState[0] == 2){
306         continuation_offset = big_endian_read_16(continuationState, 1);
307     }
308 
309     // get service record
310     service_record_item_t * item = sdp_get_record_item_for_handle(serviceRecordHandle);
311     if (!item){
312         // service record handle doesn't exist
313         return sdp_create_error_response(transaction_id, 0x0002); /// invalid Service Record Handle
314     }
315 
316 
317     // AttributeList - starts at offset 7
318     uint16_t pos = 7;
319 
320     if (continuation_offset == 0){
321 
322         // get size of this record
323         uint16_t filtered_attributes_size = sdp_get_filtered_size(item->service_record, attributeIDList);
324 
325         // store DES
326         de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, filtered_attributes_size);
327         maximumAttributeByteCount -= 3;
328         pos += 3;
329     }
330 
331     // copy maximumAttributeByteCount from record
332     uint16_t bytes_used;
333     int complete = sdp_filter_attributes_in_attributeIDList(item->service_record, attributeIDList, continuation_offset, maximumAttributeByteCount, &bytes_used, &sdp_response_buffer[pos]);
334     pos += bytes_used;
335 
336     uint16_t attributeListByteCount = pos - 7;
337 
338     if (complete) {
339         sdp_response_buffer[pos++] = 0;
340     } else {
341         continuation_offset += bytes_used;
342         sdp_response_buffer[pos++] = 2;
343         big_endian_store_16(sdp_response_buffer, pos, continuation_offset);
344         pos += 2;
345     }
346 
347     // header
348     sdp_response_buffer[0] = SDP_ServiceAttributeResponse;
349     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
350     big_endian_store_16(sdp_response_buffer, 3, pos - 5);  // size of variable payload
351     big_endian_store_16(sdp_response_buffer, 5, attributeListByteCount);
352 
353     return pos;
354 }
355 
356 static uint16_t sdp_get_size_for_service_search_attribute_response(uint8_t * serviceSearchPattern, uint8_t * attributeIDList){
357     uint16_t total_response_size = 0;
358     btstack_linked_item_t *it;
359     for (it = (btstack_linked_item_t *) sdp_server_service_records; it ; it = it->next){
360         service_record_item_t * item = (service_record_item_t *) it;
361 
362         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
363 
364         // for all service records that match
365         total_response_size += 3 + sdp_get_filtered_size(item->service_record, attributeIDList);
366     }
367     return total_response_size;
368 }
369 
370 int sdp_handle_service_search_attribute_request(uint8_t * packet, uint16_t remote_mtu){
371 
372     // SDP header before attribute sevice list: 7
373     // Continuation, worst case: 5
374 
375     // get request details
376     uint16_t  transaction_id = big_endian_read_16(packet, 1);
377     uint16_t  param_len = big_endian_read_16(packet, 3);
378     uint8_t * serviceSearchPattern = &packet[5];
379     uint16_t  serviceSearchPatternLen = de_get_len_safe(serviceSearchPattern, param_len);
380     // assert serviceSearchPattern header is contained in param_len
381     if (!serviceSearchPatternLen) return 0;
382     param_len -= serviceSearchPatternLen;
383     // assert maximumAttributeByteCount contained in param_len
384     if (param_len < 2) return 0;
385     uint16_t  maximumAttributeByteCount = big_endian_read_16(packet, 5 + serviceSearchPatternLen);
386     param_len -= 2;
387     uint8_t * attributeIDList = &packet[5+serviceSearchPatternLen+2];
388     uint16_t  attributeIDListLen = de_get_len_safe(attributeIDList, param_len);
389     if (!sdp_attribute_list_valid(attributeIDList) == false){
390         return sdp_create_error_response(transaction_id, 0x0003); /// invalid request syntax
391     }
392     // assert attributeIDList is contained in param_len
393     if (!attributeIDListLen) return 0;
394     // assert continuation state len is contained in param_len
395     if (param_len < 1) return 0;
396     uint8_t * continuationState = &packet[5+serviceSearchPatternLen+2+attributeIDListLen];
397     // assert continuation state is contained in param_len
398     if ((1 + continuationState[0]) > param_len) return 0;
399 
400     // calc maximumAttributeByteCount based on remote MTU, SDP header and reserved Continuation block
401     uint16_t maximumAttributeByteCount2 = remote_mtu - 12;
402     if (maximumAttributeByteCount2 < maximumAttributeByteCount) {
403         maximumAttributeByteCount = maximumAttributeByteCount2;
404     }
405 
406     // continuation state contains: index of next service record to examine
407     // continuation state contains: byte offset into this service record
408     uint16_t continuation_service_index = 0;
409     uint16_t continuation_offset = 0;
410     if (continuationState[0] == 4){
411         continuation_service_index = big_endian_read_16(continuationState, 1);
412         continuation_offset = big_endian_read_16(continuationState, 3);
413     }
414 
415     // log_info("--> sdp_handle_service_search_attribute_request, cont %u/%u, max %u", continuation_service_index, continuation_offset, maximumAttributeByteCount);
416 
417     // AttributeLists - starts at offset 7
418     uint16_t pos = 7;
419 
420     // add DES with total size for first request
421     if ((continuation_service_index == 0) && (continuation_offset == 0)){
422         uint16_t total_response_size = sdp_get_size_for_service_search_attribute_response(serviceSearchPattern, attributeIDList);
423         de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, total_response_size);
424         // log_info("total response size %u", total_response_size);
425         pos += 3;
426         maximumAttributeByteCount -= 3;
427     }
428 
429     // create attribute list
430     int      first_answer = 1;
431     int      continuation = 0;
432     uint16_t current_service_index = 0;
433     btstack_linked_item_t *it = (btstack_linked_item_t *) sdp_server_service_records;
434     for ( ; it ; it = it->next, ++current_service_index){
435         service_record_item_t * item = (service_record_item_t *) it;
436 
437         if (current_service_index < continuation_service_index ) continue;
438         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
439 
440         if (continuation_offset == 0){
441 
442             // get size of this record
443             uint16_t filtered_attributes_size = sdp_get_filtered_size(item->service_record, attributeIDList);
444 
445             // stop if complete record doesn't fits into response but we already have a partial response
446             if (((filtered_attributes_size + 3) > maximumAttributeByteCount) && !first_answer) {
447                 continuation = 1;
448                 break;
449             }
450 
451             // store DES
452             de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, filtered_attributes_size);
453             pos += 3;
454             maximumAttributeByteCount -= 3;
455         }
456 
457         first_answer = 0;
458 
459         // copy maximumAttributeByteCount from record
460         uint16_t bytes_used;
461         int complete = sdp_filter_attributes_in_attributeIDList(item->service_record, attributeIDList, continuation_offset, maximumAttributeByteCount, &bytes_used, &sdp_response_buffer[pos]);
462         pos += bytes_used;
463         maximumAttributeByteCount -= bytes_used;
464 
465         if (complete) {
466             continuation_offset = 0;
467             continue;
468         }
469 
470         continuation = 1;
471         continuation_offset += bytes_used;
472         break;
473     }
474 
475     uint16_t attributeListsByteCount = pos - 7;
476 
477     // Continuation State
478     if (continuation){
479         sdp_response_buffer[pos++] = 4;
480         big_endian_store_16(sdp_response_buffer, pos, (uint16_t) current_service_index);
481         pos += 2;
482         big_endian_store_16(sdp_response_buffer, pos, continuation_offset);
483         pos += 2;
484     } else {
485         // complete
486         sdp_response_buffer[pos++] = 0;
487     }
488 
489     // create SDP header
490     sdp_response_buffer[0] = SDP_ServiceSearchAttributeResponse;
491     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
492     big_endian_store_16(sdp_response_buffer, 3, pos - 5);  // size of variable payload
493     big_endian_store_16(sdp_response_buffer, 5, attributeListsByteCount);
494 
495     return pos;
496 }
497 
498 static void sdp_respond(void){
499     if (!sdp_server_response_size ) return;
500     if (!sdp_server_l2cap_cid) return;
501 
502     // update state before sending packet (avoid getting called when new l2cap credit gets emitted)
503     uint16_t size = sdp_server_response_size;
504     sdp_server_response_size = 0;
505     l2cap_send(sdp_server_l2cap_cid, sdp_response_buffer, size);
506 }
507 
508 // @pre space in list
509 static void sdp_waiting_list_add(uint16_t cid){
510     sdp_server_l2cap_waiting_list_cids[sdp_server_l2cap_waiting_list_count++] = cid;
511 }
512 
513 // @pre at least one item in list
514 static uint16_t sdp_waiting_list_get(void){
515     uint16_t cid = sdp_server_l2cap_waiting_list_cids[0];
516     sdp_server_l2cap_waiting_list_count--;
517     if (sdp_server_l2cap_waiting_list_count){
518         memmove(&sdp_server_l2cap_waiting_list_cids[0], &sdp_server_l2cap_waiting_list_cids[1], sdp_server_l2cap_waiting_list_count * sizeof(uint16_t));
519     }
520     return cid;
521 }
522 
523 // we assume that we don't get two requests in a row
524 static void sdp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
525 	uint16_t transaction_id;
526     sdp_pdu_id_t pdu_id;
527     uint16_t remote_mtu;
528     uint16_t param_len;
529 
530 	switch (packet_type) {
531 
532 		case L2CAP_DATA_PACKET:
533             pdu_id = (sdp_pdu_id_t) packet[0];
534             transaction_id = big_endian_read_16(packet, 1);
535             param_len = big_endian_read_16(packet, 3);
536             remote_mtu = l2cap_get_remote_mtu_for_local_cid(channel);
537             // account for our buffer
538             if (remote_mtu > SDP_RESPONSE_BUFFER_SIZE){
539                 remote_mtu = SDP_RESPONSE_BUFFER_SIZE;
540             }
541             // validate parm_len against packet size
542             if ((param_len + 5) > size) {
543                 // just clear pdu_id
544                 pdu_id = SDP_ErrorResponse;
545             }
546 
547             // log_info("SDP Request: type %u, transaction id %u, len %u, mtu %u", pdu_id, transaction_id, param_len, remote_mtu);
548             switch (pdu_id){
549 
550                 case SDP_ServiceSearchRequest:
551                     sdp_server_response_size = sdp_handle_service_search_request(packet, remote_mtu);
552                     break;
553 
554                 case SDP_ServiceAttributeRequest:
555                     sdp_server_response_size = sdp_handle_service_attribute_request(packet, remote_mtu);
556                     break;
557 
558                 case SDP_ServiceSearchAttributeRequest:
559                     sdp_server_response_size = sdp_handle_service_search_attribute_request(packet, remote_mtu);
560                     break;
561 
562                 default:
563                     sdp_server_response_size = sdp_create_error_response(transaction_id, 0x0003); // invalid syntax
564                     break;
565             }
566             if (!sdp_server_response_size) break;
567             l2cap_request_can_send_now_event(sdp_server_l2cap_cid);
568 			break;
569 
570 		case HCI_EVENT_PACKET:
571 
572 			switch (hci_event_packet_get_type(packet)) {
573 
574 				case L2CAP_EVENT_INCOMING_CONNECTION:
575                     if (sdp_server_l2cap_cid) {
576                         // try to queue up
577                         if (sdp_server_l2cap_waiting_list_count < SDP_WAITING_LIST_MAX_COUNT){
578                             sdp_waiting_list_add(channel);
579                             log_info("busy, queing incoming cid 0x%04x, now %u waiting", channel, sdp_server_l2cap_waiting_list_count);
580                             break;
581                         }
582 
583                         // CONNECTION REJECTED DUE TO LIMITED RESOURCES
584                         l2cap_decline_connection(channel);
585                         break;
586                     }
587                     // accept
588                     sdp_server_l2cap_cid = channel;
589                     sdp_server_response_size = 0;
590                     l2cap_accept_connection(sdp_server_l2cap_cid);
591 					break;
592 
593                 case L2CAP_EVENT_CHANNEL_OPENED:
594                     if (packet[2]) {
595                         // open failed -> reset
596                         sdp_server_l2cap_cid = 0;
597                     }
598                     break;
599 
600                 case L2CAP_EVENT_CAN_SEND_NOW:
601                     sdp_respond();
602                     break;
603 
604                 case L2CAP_EVENT_CHANNEL_CLOSED:
605                     if (channel == sdp_server_l2cap_cid){
606                         // reset
607                         sdp_server_l2cap_cid = 0;
608 
609                         // other request queued?
610                         if (!sdp_server_l2cap_waiting_list_count) break;
611 
612                         // get first item
613                         sdp_server_l2cap_cid = sdp_waiting_list_get();
614 
615                         log_info("disconnect, accept queued cid 0x%04x, now %u waiting", sdp_server_l2cap_cid, sdp_server_l2cap_waiting_list_count);
616 
617                         // accept connection
618                         sdp_server_response_size = 0;
619                         l2cap_accept_connection(sdp_server_l2cap_cid);
620                     }
621                     break;
622 
623 				default:
624 					// other event
625 					break;
626 			}
627 			break;
628 
629 		default:
630 			// other packet type
631 			break;
632 	}
633 }
634 
635