xref: /btstack/src/classic/sdp_server.c (revision 22d58ff8de23f4f8df27e78fade3aa864f1db00c)
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 #ifdef ENABLE_TESTING_SUPPORT
88 static bool sdp_server_testing_single_record_reponse = false;
89 #endif
90 
91 void sdp_init(void){
92     sdp_server_next_service_record_handle = ((uint32_t) MAX_RESERVED_SERVICE_RECORD_HANDLE) + 2;
93     // register with l2cap psm sevices - max MTU
94     l2cap_register_service(sdp_packet_handler, BLUETOOTH_PSM_SDP, 0xffff, LEVEL_0);
95 }
96 
97 void sdp_deinit(void){
98     sdp_server_service_records = NULL;
99     sdp_server_l2cap_cid = 0;
100     sdp_server_response_size = 0;
101     sdp_server_l2cap_waiting_list_count = 0;
102 }
103 
104 uint32_t sdp_get_service_record_handle(const uint8_t * record){
105     // TODO: make sdp_get_attribute_value_for_attribute_id accept const data to remove cast
106     uint8_t * serviceRecordHandleAttribute = sdp_get_attribute_value_for_attribute_id((uint8_t *)record, BLUETOOTH_ATTRIBUTE_SERVICE_RECORD_HANDLE);
107     if (!serviceRecordHandleAttribute) return 0;
108     if (de_get_element_type(serviceRecordHandleAttribute) != DE_UINT) return 0;
109     if (de_get_size_type(serviceRecordHandleAttribute) != DE_SIZE_32) return 0;
110     return big_endian_read_32(serviceRecordHandleAttribute, 1);
111 }
112 
113 static service_record_item_t * sdp_get_record_item_for_handle(uint32_t handle){
114     btstack_linked_item_t *it;
115     for (it = (btstack_linked_item_t *) sdp_server_service_records; it ; it = it->next){
116         service_record_item_t * item = (service_record_item_t *) it;
117         if (item->service_record_handle == handle){
118             return item;
119         }
120     }
121     return NULL;
122 }
123 
124 uint8_t * sdp_get_record_for_handle(uint32_t handle){
125     service_record_item_t * record_item =  sdp_get_record_item_for_handle(handle);
126     if (!record_item) return NULL;
127     return record_item->service_record;
128 }
129 
130 // get next free, unregistered service record handle
131 uint32_t sdp_create_service_record_handle(void){
132     uint32_t handle = 0;
133     do {
134         handle = sdp_server_next_service_record_handle++;
135         if (sdp_get_record_item_for_handle(handle)) handle = 0;
136     } while (handle == 0);
137     return handle;
138 }
139 
140 /**
141  * @brief Register Service Record with database using ServiceRecordHandle stored in record
142  * @pre AttributeIDs are in ascending order
143  * @pre ServiceRecordHandle is first attribute and valid
144  * @param record is not copied!
145  * @result status
146  */
147 uint8_t sdp_register_service(const uint8_t * record){
148 
149     // validate service record handle. it must: exist, be in valid range, not have been already used
150     uint32_t record_handle = sdp_get_service_record_handle(record);
151     if (!record_handle) return SDP_HANDLE_INVALID;
152     if (record_handle <= MAX_RESERVED_SERVICE_RECORD_HANDLE) return SDP_HANDLE_INVALID;
153     if (sdp_get_record_item_for_handle(record_handle)) return SDP_HANDLE_ALREADY_REGISTERED;
154 
155     // alloc memory for new service_record_item
156     service_record_item_t * newRecordItem = btstack_memory_service_record_item_get();
157     if (!newRecordItem) return BTSTACK_MEMORY_ALLOC_FAILED;
158 
159     // set handle and record
160     newRecordItem->service_record_handle = record_handle;
161     newRecordItem->service_record = (uint8_t*) record;
162 
163     // add to linked list
164     btstack_linked_list_add(&sdp_server_service_records, (btstack_linked_item_t *) newRecordItem);
165 
166     return 0;
167 }
168 
169 //
170 // unregister service record
171 //
172 void sdp_unregister_service(uint32_t service_record_handle){
173     service_record_item_t * record_item = sdp_get_record_item_for_handle(service_record_handle);
174     if (!record_item) return;
175     btstack_linked_list_remove(&sdp_server_service_records, (btstack_linked_item_t *) record_item);
176     btstack_memory_service_record_item_free(record_item);
177 }
178 
179 // PDU
180 // PDU ID (1), Transaction ID (2), Param Length (2), Param 1, Param 2, ..
181 
182 static int sdp_create_error_response(uint16_t transaction_id, uint16_t error_code){
183     sdp_response_buffer[0] = SDP_ErrorResponse;
184     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
185     big_endian_store_16(sdp_response_buffer, 3, 2);
186     big_endian_store_16(sdp_response_buffer, 5, error_code); // invalid syntax
187     return 7;
188 }
189 
190 int sdp_handle_service_search_request(uint8_t * packet, uint16_t remote_mtu){
191 
192     // get request details
193     uint16_t  transaction_id = big_endian_read_16(packet, 1);
194     uint16_t  param_len = big_endian_read_16(packet, 3);
195     uint8_t * serviceSearchPattern = &packet[5];
196     uint16_t  serviceSearchPatternLen = de_get_len_safe(serviceSearchPattern, param_len);
197     // assert service search pattern is contained
198     if (!serviceSearchPatternLen) return 0;
199     param_len -= serviceSearchPatternLen;
200     // assert max record count is contained
201     if (param_len < 2) return 0;
202     uint16_t  maximumServiceRecordCount = big_endian_read_16(packet, 5 + serviceSearchPatternLen);
203     param_len -= 2;
204     // assert continuation state len is contained in param_len
205     if (param_len < 1) return 0;
206     uint8_t * continuationState = &packet[5+serviceSearchPatternLen+2];
207     // assert continuation state is contained in param_len
208     if ((1 + continuationState[0]) > param_len) return 0;
209 
210     // calc maximumServiceRecordCount based on remote MTU
211     uint16_t maxNrServiceRecordsPerResponse = (remote_mtu - (9+3))/4;
212 #ifdef ENABLE_TESTING_SUPPORT
213     if (sdp_server_testing_single_record_reponse){
214         maxNrServiceRecordsPerResponse = 1;
215     }
216 #endif
217 
218     // continuation state contains index of next service record to examine
219     int      continuation = 0;
220     uint16_t continuation_index = 0;
221     if (continuationState[0] == 2){
222         continuation_index = big_endian_read_16(continuationState, 1);
223     }
224 
225     // get and limit total count
226     btstack_linked_item_t *it;
227     uint16_t total_service_count   = 0;
228     for (it = (btstack_linked_item_t *) sdp_server_service_records; it ; it = it->next){
229         service_record_item_t * item = (service_record_item_t *) it;
230         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
231         total_service_count++;
232     }
233     if (total_service_count > maximumServiceRecordCount){
234         total_service_count = maximumServiceRecordCount;
235     }
236 
237     // ServiceRecordHandleList at 9
238     uint16_t pos = 9;
239     uint16_t current_service_count  = 0;
240     uint16_t current_service_index  = 0;
241     uint16_t matching_service_count = 0;
242     for (it = (btstack_linked_item_t *) sdp_server_service_records; it ; it = it->next, ++current_service_index){
243         service_record_item_t * item = (service_record_item_t *) it;
244 
245         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
246         matching_service_count++;
247 
248         if (current_service_index < continuation_index) continue;
249 
250         big_endian_store_32(sdp_response_buffer, pos, item->service_record_handle);
251         pos += 4;
252         current_service_count++;
253 
254         if (matching_service_count >= total_service_count) break;
255 
256         if (current_service_count >= maxNrServiceRecordsPerResponse){
257             continuation = 1;
258             continuation_index = current_service_index + 1;
259             break;
260         }
261     }
262 
263     // Store continuation state
264     if (continuation) {
265         sdp_response_buffer[pos++] = 2;
266         big_endian_store_16(sdp_response_buffer, pos, continuation_index);
267         pos += 2;
268     } else {
269         sdp_response_buffer[pos++] = 0;
270     }
271 
272     // header
273     sdp_response_buffer[0] = SDP_ServiceSearchResponse;
274     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
275     big_endian_store_16(sdp_response_buffer, 3, pos - 5); // size of variable payload
276     big_endian_store_16(sdp_response_buffer, 5, total_service_count);
277     big_endian_store_16(sdp_response_buffer, 7, current_service_count);
278 
279     return pos;
280 }
281 
282 int sdp_handle_service_attribute_request(uint8_t * packet, uint16_t remote_mtu){
283 
284     // get request details
285     uint16_t  transaction_id = big_endian_read_16(packet, 1);
286     uint16_t  param_len = big_endian_read_16(packet, 3);
287     // assert serviceRecordHandle and maximumAttributeByteCount are in param_len
288     if (param_len < 6) return 0;
289     uint32_t  serviceRecordHandle = big_endian_read_32(packet, 5);
290     uint16_t  maximumAttributeByteCount = big_endian_read_16(packet, 9);
291     param_len -= 6;
292     uint8_t * attributeIDList = &packet[11];
293     uint16_t  attributeIDListLen = de_get_len_safe(attributeIDList, param_len);
294     if (!sdp_attribute_list_valid(attributeIDList) == false){
295         return sdp_create_error_response(transaction_id, 0x0003); /// invalid request syntax
296     }
297     // assert attributeIDList are in param_len
298     if (!attributeIDListLen) return 0;
299     param_len -= attributeIDListLen;
300     // assert continuation state len is contained in param_len
301     if (param_len < 1) return 0;
302     uint8_t * continuationState = &packet[11+attributeIDListLen];
303     // assert continuation state is contained in param_len
304     if ((1 + continuationState[0]) > param_len) return 0;
305 
306     // calc maximumAttributeByteCount based on remote MTU
307     uint16_t maximumAttributeByteCount2 = remote_mtu - (7+3);
308     if (maximumAttributeByteCount2 < maximumAttributeByteCount) {
309         maximumAttributeByteCount = maximumAttributeByteCount2;
310     }
311 
312     // continuation state contains the offset into the complete response
313     uint16_t continuation_offset = 0;
314     if (continuationState[0] == 2){
315         continuation_offset = big_endian_read_16(continuationState, 1);
316     }
317 
318     // get service record
319     service_record_item_t * item = sdp_get_record_item_for_handle(serviceRecordHandle);
320     if (!item){
321         // service record handle doesn't exist
322         return sdp_create_error_response(transaction_id, 0x0002); /// invalid Service Record Handle
323     }
324 
325 
326     // AttributeList - starts at offset 7
327     uint16_t pos = 7;
328 
329     if (continuation_offset == 0){
330 
331         // get size of this record
332         uint16_t filtered_attributes_size = sdp_get_filtered_size(item->service_record, attributeIDList);
333 
334         // store DES
335         de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, filtered_attributes_size);
336         maximumAttributeByteCount -= 3;
337         pos += 3;
338     }
339 
340     // copy maximumAttributeByteCount from record
341     uint16_t bytes_used;
342     int complete = sdp_filter_attributes_in_attributeIDList(item->service_record, attributeIDList, continuation_offset, maximumAttributeByteCount, &bytes_used, &sdp_response_buffer[pos]);
343     pos += bytes_used;
344 
345     uint16_t attributeListByteCount = pos - 7;
346 
347     if (complete) {
348         sdp_response_buffer[pos++] = 0;
349     } else {
350         continuation_offset += bytes_used;
351         sdp_response_buffer[pos++] = 2;
352         big_endian_store_16(sdp_response_buffer, pos, continuation_offset);
353         pos += 2;
354     }
355 
356     // header
357     sdp_response_buffer[0] = SDP_ServiceAttributeResponse;
358     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
359     big_endian_store_16(sdp_response_buffer, 3, pos - 5);  // size of variable payload
360     big_endian_store_16(sdp_response_buffer, 5, attributeListByteCount);
361 
362     return pos;
363 }
364 
365 static uint16_t sdp_get_size_for_service_search_attribute_response(uint8_t * serviceSearchPattern, uint8_t * attributeIDList){
366     uint16_t total_response_size = 0;
367     btstack_linked_item_t *it;
368     for (it = (btstack_linked_item_t *) sdp_server_service_records; it ; it = it->next){
369         service_record_item_t * item = (service_record_item_t *) it;
370 
371         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
372 
373         // for all service records that match
374         total_response_size += 3 + sdp_get_filtered_size(item->service_record, attributeIDList);
375     }
376     return total_response_size;
377 }
378 
379 int sdp_handle_service_search_attribute_request(uint8_t * packet, uint16_t remote_mtu){
380 
381     // SDP header before attribute sevice list: 7
382     // Continuation, worst case: 5
383 
384     // get request details
385     uint16_t  transaction_id = big_endian_read_16(packet, 1);
386     uint16_t  param_len = big_endian_read_16(packet, 3);
387     uint8_t * serviceSearchPattern = &packet[5];
388     uint16_t  serviceSearchPatternLen = de_get_len_safe(serviceSearchPattern, param_len);
389     // assert serviceSearchPattern header is contained in param_len
390     if (!serviceSearchPatternLen) return 0;
391     param_len -= serviceSearchPatternLen;
392     // assert maximumAttributeByteCount contained in param_len
393     if (param_len < 2) return 0;
394     uint16_t  maximumAttributeByteCount = big_endian_read_16(packet, 5 + serviceSearchPatternLen);
395     param_len -= 2;
396     uint8_t * attributeIDList = &packet[5+serviceSearchPatternLen+2];
397     uint16_t  attributeIDListLen = de_get_len_safe(attributeIDList, param_len);
398     if (!sdp_attribute_list_valid(attributeIDList) == false){
399         return sdp_create_error_response(transaction_id, 0x0003); /// invalid request syntax
400     }
401     // assert attributeIDList is contained in param_len
402     if (!attributeIDListLen) return 0;
403     // assert continuation state len is contained in param_len
404     if (param_len < 1) return 0;
405     uint8_t * continuationState = &packet[5+serviceSearchPatternLen+2+attributeIDListLen];
406     // assert continuation state is contained in param_len
407     if ((1 + continuationState[0]) > param_len) return 0;
408 
409     // calc maximumAttributeByteCount based on remote MTU, SDP header and reserved Continuation block
410     uint16_t maximumAttributeByteCount2 = remote_mtu - 12;
411     if (maximumAttributeByteCount2 < maximumAttributeByteCount) {
412         maximumAttributeByteCount = maximumAttributeByteCount2;
413     }
414 
415     // continuation state contains: index of next service record to examine
416     // continuation state contains: byte offset into this service record
417     uint16_t continuation_service_index = 0;
418     uint16_t continuation_offset = 0;
419     if (continuationState[0] == 4){
420         continuation_service_index = big_endian_read_16(continuationState, 1);
421         continuation_offset = big_endian_read_16(continuationState, 3);
422     }
423 
424     // log_info("--> sdp_handle_service_search_attribute_request, cont %u/%u, max %u", continuation_service_index, continuation_offset, maximumAttributeByteCount);
425 
426     // AttributeLists - starts at offset 7
427     uint16_t pos = 7;
428 
429     // add DES with total size for first request
430     if ((continuation_service_index == 0) && (continuation_offset == 0)){
431         uint16_t total_response_size = sdp_get_size_for_service_search_attribute_response(serviceSearchPattern, attributeIDList);
432         de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, total_response_size);
433         // log_info("total response size %u", total_response_size);
434         pos += 3;
435         maximumAttributeByteCount -= 3;
436     }
437 
438     // create attribute list
439     int      first_answer = 1;
440     int      continuation = 0;
441     uint16_t current_service_index = 0;
442     btstack_linked_item_t *it = (btstack_linked_item_t *) sdp_server_service_records;
443     for ( ; it ; it = it->next, ++current_service_index){
444         service_record_item_t * item = (service_record_item_t *) it;
445 
446         if (current_service_index < continuation_service_index ) continue;
447         if (!sdp_record_matches_service_search_pattern(item->service_record, serviceSearchPattern)) continue;
448 
449         if (continuation_offset == 0){
450 
451             // get size of this record
452             uint16_t filtered_attributes_size = sdp_get_filtered_size(item->service_record, attributeIDList);
453 
454             // stop if complete record doesn't fits into response but we already have a partial response
455             if (((filtered_attributes_size + 3) > maximumAttributeByteCount) && !first_answer) {
456                 continuation = 1;
457                 break;
458             }
459 
460             // store DES
461             de_store_descriptor_with_len(&sdp_response_buffer[pos], DE_DES, DE_SIZE_VAR_16, filtered_attributes_size);
462             pos += 3;
463             maximumAttributeByteCount -= 3;
464         }
465 
466         first_answer = 0;
467 
468         // copy maximumAttributeByteCount from record
469         uint16_t bytes_used;
470         int complete = sdp_filter_attributes_in_attributeIDList(item->service_record, attributeIDList, continuation_offset, maximumAttributeByteCount, &bytes_used, &sdp_response_buffer[pos]);
471         pos += bytes_used;
472         maximumAttributeByteCount -= bytes_used;
473 
474         if (complete) {
475             continuation_offset = 0;
476             continue;
477         }
478 
479         continuation = 1;
480         continuation_offset += bytes_used;
481         break;
482     }
483 
484     uint16_t attributeListsByteCount = pos - 7;
485 
486     // Continuation State
487     if (continuation){
488         sdp_response_buffer[pos++] = 4;
489         big_endian_store_16(sdp_response_buffer, pos, (uint16_t) current_service_index);
490         pos += 2;
491         big_endian_store_16(sdp_response_buffer, pos, continuation_offset);
492         pos += 2;
493     } else {
494         // complete
495         sdp_response_buffer[pos++] = 0;
496     }
497 
498     // create SDP header
499     sdp_response_buffer[0] = SDP_ServiceSearchAttributeResponse;
500     big_endian_store_16(sdp_response_buffer, 1, transaction_id);
501     big_endian_store_16(sdp_response_buffer, 3, pos - 5);  // size of variable payload
502     big_endian_store_16(sdp_response_buffer, 5, attributeListsByteCount);
503 
504     return pos;
505 }
506 
507 static void sdp_respond(void){
508     if (!sdp_server_response_size ) return;
509     if (!sdp_server_l2cap_cid) return;
510 
511     // update state before sending packet (avoid getting called when new l2cap credit gets emitted)
512     uint16_t size = sdp_server_response_size;
513     sdp_server_response_size = 0;
514     l2cap_send(sdp_server_l2cap_cid, sdp_response_buffer, size);
515 }
516 
517 // @pre space in list
518 static void sdp_waiting_list_add(uint16_t cid){
519     sdp_server_l2cap_waiting_list_cids[sdp_server_l2cap_waiting_list_count++] = cid;
520 }
521 
522 // @pre at least one item in list
523 static uint16_t sdp_waiting_list_get(void){
524     uint16_t cid = sdp_server_l2cap_waiting_list_cids[0];
525     sdp_server_l2cap_waiting_list_count--;
526     if (sdp_server_l2cap_waiting_list_count){
527         memmove(&sdp_server_l2cap_waiting_list_cids[0], &sdp_server_l2cap_waiting_list_cids[1], sdp_server_l2cap_waiting_list_count * sizeof(uint16_t));
528     }
529     return cid;
530 }
531 
532 // we assume that we don't get two requests in a row
533 static void sdp_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
534 	uint16_t transaction_id;
535     sdp_pdu_id_t pdu_id;
536     uint16_t remote_mtu;
537     uint16_t param_len;
538 
539 	switch (packet_type) {
540 
541 		case L2CAP_DATA_PACKET:
542             pdu_id = (sdp_pdu_id_t) packet[0];
543             transaction_id = big_endian_read_16(packet, 1);
544             param_len = big_endian_read_16(packet, 3);
545             remote_mtu = l2cap_get_remote_mtu_for_local_cid(channel);
546             // account for our buffer
547             if (remote_mtu > SDP_RESPONSE_BUFFER_SIZE){
548                 remote_mtu = SDP_RESPONSE_BUFFER_SIZE;
549             }
550             // validate parm_len against packet size
551             if ((param_len + 5) > size) {
552                 // just clear pdu_id
553                 pdu_id = SDP_ErrorResponse;
554             }
555 
556             // log_info("SDP Request: type %u, transaction id %u, len %u, mtu %u", pdu_id, transaction_id, param_len, remote_mtu);
557             switch (pdu_id){
558 
559                 case SDP_ServiceSearchRequest:
560                     sdp_server_response_size = sdp_handle_service_search_request(packet, remote_mtu);
561                     break;
562 
563                 case SDP_ServiceAttributeRequest:
564                     sdp_server_response_size = sdp_handle_service_attribute_request(packet, remote_mtu);
565                     break;
566 
567                 case SDP_ServiceSearchAttributeRequest:
568                     sdp_server_response_size = sdp_handle_service_search_attribute_request(packet, remote_mtu);
569                     break;
570 
571                 default:
572                     sdp_server_response_size = sdp_create_error_response(transaction_id, 0x0004); // invalid PDU size
573                     break;
574             }
575             if (!sdp_server_response_size) break;
576             l2cap_request_can_send_now_event(sdp_server_l2cap_cid);
577 			break;
578 
579 		case HCI_EVENT_PACKET:
580 
581 			switch (hci_event_packet_get_type(packet)) {
582 
583 				case L2CAP_EVENT_INCOMING_CONNECTION:
584                     if (sdp_server_l2cap_cid) {
585                         // try to queue up
586                         if (sdp_server_l2cap_waiting_list_count < SDP_WAITING_LIST_MAX_COUNT){
587                             sdp_waiting_list_add(channel);
588                             log_info("busy, queing incoming cid 0x%04x, now %u waiting", channel, sdp_server_l2cap_waiting_list_count);
589                             break;
590                         }
591 
592                         // CONNECTION REJECTED DUE TO LIMITED RESOURCES
593                         l2cap_decline_connection(channel);
594                         break;
595                     }
596                     // accept
597                     sdp_server_l2cap_cid = channel;
598                     sdp_server_response_size = 0;
599                     l2cap_accept_connection(sdp_server_l2cap_cid);
600 					break;
601 
602                 case L2CAP_EVENT_CHANNEL_OPENED:
603                     if (packet[2]) {
604                         // open failed -> reset
605                         sdp_server_l2cap_cid = 0;
606                     }
607                     break;
608 
609                 case L2CAP_EVENT_CAN_SEND_NOW:
610                     sdp_respond();
611                     break;
612 
613                 case L2CAP_EVENT_CHANNEL_CLOSED:
614                     if (channel == sdp_server_l2cap_cid){
615                         // reset
616                         sdp_server_l2cap_cid = 0;
617 
618                         // other request queued?
619                         if (!sdp_server_l2cap_waiting_list_count) break;
620 
621                         // get first item
622                         sdp_server_l2cap_cid = sdp_waiting_list_get();
623 
624                         log_info("disconnect, accept queued cid 0x%04x, now %u waiting", sdp_server_l2cap_cid, sdp_server_l2cap_waiting_list_count);
625 
626                         // accept connection
627                         sdp_server_response_size = 0;
628                         l2cap_accept_connection(sdp_server_l2cap_cid);
629                     }
630                     break;
631 
632 				default:
633 					// other event
634 					break;
635 			}
636 			break;
637 
638 		default:
639 			// other packet type
640 			break;
641 	}
642 }
643 
644 #ifdef ENABLE_TESTING_SUPPORT
645 void sdp_server_set_single_record_response(bool enable){
646     sdp_server_testing_single_record_reponse = enable;
647 }
648 #endif