xref: /btstack/src/l2cap.c (revision 6c927b22a98b3f4b0e3ed7d77829cb530efde76d)
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 /*
39  *  l2cap.c
40  *
41  *  Logical Link Control and Adaption Protocl (L2CAP)
42  *
43  *  Created by Matthias Ringwald on 5/16/09.
44  */
45 
46 #include "l2cap.h"
47 #include "hci.h"
48 #include "hci_dump.h"
49 #include "btstack_debug.h"
50 #include "btstack_memory.h"
51 
52 #include <stdarg.h>
53 #include <string.h>
54 
55 #include <stdio.h>
56 
57 // nr of buffered acl packets in outgoing queue to get max performance
58 #define NR_BUFFERED_ACL_PACKETS 3
59 
60 // used to cache l2cap rejects, echo, and informational requests
61 #define NR_PENDING_SIGNALING_RESPONSES 3
62 
63 // offsets for L2CAP SIGNALING COMMANDS
64 #define L2CAP_SIGNALING_COMMAND_CODE_OFFSET   0
65 #define L2CAP_SIGNALING_COMMAND_SIGID_OFFSET  1
66 #define L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET 2
67 #define L2CAP_SIGNALING_COMMAND_DATA_OFFSET   4
68 
69 // internal table
70 #define L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL 0
71 #define L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL  1
72 #define L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL 2
73 #define L2CAP_FIXED_CHANNEL_TABLE_SIZE (L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL+1)
74 
75 // prototypes
76 static void l2cap_finialize_channel_close(l2cap_channel_t *channel);
77 static inline l2cap_service_t * l2cap_get_service(uint16_t psm);
78 static void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status);
79 static void l2cap_emit_can_send_now(btstack_packet_handler_t packet_handler, uint16_t channel);
80 static void l2cap_emit_channel_closed(l2cap_channel_t *channel);
81 static void l2cap_emit_connection_request(l2cap_channel_t *channel);
82 static int  l2cap_channel_ready_for_open(l2cap_channel_t *channel);
83 static void l2cap_hci_event_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
84 static void l2cap_acl_handler(uint8_t packet_type, uint8_t *packet, uint16_t size );
85 
86 typedef struct l2cap_fixed_channel {
87     btstack_packet_handler_t callback;
88     uint8_t waiting_for_can_send_now;
89 } l2cap_fixed_channel_t;
90 
91 static btstack_linked_list_t l2cap_channels;
92 static btstack_linked_list_t l2cap_services;
93 static btstack_linked_list_t l2cap_le_channels;
94 static btstack_linked_list_t l2cap_le_services;
95 
96 // used to cache l2cap rejects, echo, and informational requests
97 static l2cap_signaling_response_t signaling_responses[NR_PENDING_SIGNALING_RESPONSES];
98 static int signaling_responses_pending;
99 
100 static uint8_t require_security_level2_for_outgoing_sdp;
101 
102 static btstack_packet_callback_registration_t hci_event_callback_registration;
103 
104 static btstack_packet_handler_t l2cap_event_packet_handler;
105 static l2cap_fixed_channel_t fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_SIZE];
106 
107 static uint16_t l2cap_fixed_channel_table_channel_id_for_index(int index){
108     switch (index){
109         case L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL:
110             return L2CAP_CID_ATTRIBUTE_PROTOCOL;
111         case L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL:
112             return L2CAP_CID_SECURITY_MANAGER_PROTOCOL;
113         case L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL:
114             return L2CAP_CID_CONNECTIONLESS_CHANNEL;
115         default:
116             return 0;
117     }
118 }
119 static int l2cap_fixed_channel_table_index_for_channel_id(uint16_t channel_id){
120     switch (channel_id){
121         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
122             return L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL;
123         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
124             return  L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL;
125         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
126             return  L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL;
127         default:
128             return -1;
129         }
130 }
131 
132 static int l2cap_fixed_channel_table_index_is_le(int index){
133     if (index == L2CAP_CID_CONNECTIONLESS_CHANNEL) return 0;
134     return 1;
135 }
136 
137 void l2cap_init(void){
138     signaling_responses_pending = 0;
139 
140     l2cap_channels = NULL;
141     l2cap_services = NULL;
142     l2cap_le_services = NULL;
143     l2cap_le_channels = NULL;
144 
145     l2cap_event_packet_handler = NULL;
146     memset(fixed_channels, 0, sizeof(fixed_channels));
147 
148     require_security_level2_for_outgoing_sdp = 0;
149 
150     //
151     // register callback with HCI
152     //
153     hci_event_callback_registration.callback = &l2cap_hci_event_handler;
154     hci_add_event_handler(&hci_event_callback_registration);
155 
156     hci_register_acl_packet_handler(&l2cap_acl_handler);
157 
158     hci_connectable_control(0); // no services yet
159 }
160 
161 void l2cap_register_packet_handler(void (*handler)(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size)){
162     l2cap_event_packet_handler = handler;
163 }
164 
165 static void l2cap_dispatch_to_channel(l2cap_channel_t *channel, uint8_t type, uint8_t * data, uint16_t size){
166     (* (channel->packet_handler))(type, channel->local_cid, data, size);
167 }
168 
169 void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status) {
170     log_info("L2CAP_EVENT_CHANNEL_OPENED status 0x%x addr %s handle 0x%x psm 0x%x local_cid 0x%x remote_cid 0x%x local_mtu %u, remote_mtu %u, flush_timeout %u",
171              status, bd_addr_to_str(channel->address), channel->handle, channel->psm,
172              channel->local_cid, channel->remote_cid, channel->local_mtu, channel->remote_mtu, channel->flush_timeout);
173     uint8_t event[23];
174     event[0] = L2CAP_EVENT_CHANNEL_OPENED;
175     event[1] = sizeof(event) - 2;
176     event[2] = status;
177     reverse_bd_addr(channel->address, &event[3]);
178     little_endian_store_16(event,  9, channel->handle);
179     little_endian_store_16(event, 11, channel->psm);
180     little_endian_store_16(event, 13, channel->local_cid);
181     little_endian_store_16(event, 15, channel->remote_cid);
182     little_endian_store_16(event, 17, channel->local_mtu);
183     little_endian_store_16(event, 19, channel->remote_mtu);
184     little_endian_store_16(event, 21, channel->flush_timeout);
185     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
186     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
187 
188     // if channel opened successfully, also send can send now if possible
189     if (status) return;
190     if (hci_can_send_acl_packet_now(channel->handle)){
191         l2cap_emit_can_send_now(channel->packet_handler, channel->local_cid);
192     } else {
193         channel->waiting_for_can_send_now = 1;
194     }
195 }
196 
197 void l2cap_emit_channel_closed(l2cap_channel_t *channel) {
198     log_info("L2CAP_EVENT_CHANNEL_CLOSED local_cid 0x%x", channel->local_cid);
199     uint8_t event[4];
200     event[0] = L2CAP_EVENT_CHANNEL_CLOSED;
201     event[1] = sizeof(event) - 2;
202     little_endian_store_16(event, 2, channel->local_cid);
203     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
204     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
205 }
206 
207 void l2cap_emit_connection_request(l2cap_channel_t *channel) {
208     log_info("L2CAP_EVENT_INCOMING_CONNECTION addr %s handle 0x%x psm 0x%x local_cid 0x%x remote_cid 0x%x",
209              bd_addr_to_str(channel->address), channel->handle,  channel->psm, channel->local_cid, channel->remote_cid);
210     uint8_t event[16];
211     event[0] = L2CAP_EVENT_INCOMING_CONNECTION;
212     event[1] = sizeof(event) - 2;
213     reverse_bd_addr(channel->address, &event[2]);
214     little_endian_store_16(event,  8, channel->handle);
215     little_endian_store_16(event, 10, channel->psm);
216     little_endian_store_16(event, 12, channel->local_cid);
217     little_endian_store_16(event, 14, channel->remote_cid);
218     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
219     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
220 }
221 
222 static void l2cap_emit_can_send_now(btstack_packet_handler_t packet_handler, uint16_t channel) {
223     log_info("L2CAP_EVENT_CHANNEL_CAN_SEND_NOW local_cid 0x%x", channel);
224     uint8_t event[4];
225     event[0] = L2CAP_EVENT_CAN_SEND_NOW;
226     event[1] = sizeof(event) - 2;
227     little_endian_store_16(event, 2, channel);
228     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
229     packet_handler(HCI_EVENT_PACKET, channel, event, sizeof(event));
230 }
231 
232 static void l2cap_emit_connection_parameter_update_response(uint16_t handle, uint16_t result){
233     uint8_t event[6];
234     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_RESPONSE;
235     event[1] = 4;
236     little_endian_store_16(event, 2, handle);
237     little_endian_store_16(event, 4, result);
238     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
239     if (!l2cap_event_packet_handler) return;
240     (*l2cap_event_packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
241 }
242 
243 static l2cap_channel_t * l2cap_get_channel_for_local_cid(uint16_t local_cid){
244     btstack_linked_list_iterator_t it;
245     btstack_linked_list_iterator_init(&it, &l2cap_channels);
246     while (btstack_linked_list_iterator_has_next(&it)){
247         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
248         if ( channel->local_cid == local_cid) {
249             return channel;
250         }
251     }
252     return NULL;
253 }
254 
255 int  l2cap_can_send_packet_now(uint16_t local_cid){
256     l2cap_channel_t *channel = l2cap_get_channel_for_local_cid(local_cid);
257     if (!channel) return 0;
258     int can_send = hci_can_send_acl_packet_now(channel->handle);
259     if (!can_send){
260         channel->waiting_for_can_send_now = 1;
261     }
262     return can_send;
263 }
264 
265 int  l2cap_can_send_prepared_packet_now(uint16_t local_cid){
266     l2cap_channel_t *channel = l2cap_get_channel_for_local_cid(local_cid);
267     if (!channel) return 0;
268     int can_send = hci_can_send_prepared_acl_packet_now(channel->handle);
269     if (!can_send){
270         channel->waiting_for_can_send_now = 1;
271     }
272     return can_send;
273 }
274 
275 int  l2cap_can_send_fixed_channel_packet_now(uint16_t handle, uint16_t channel_id){
276     int can_send = hci_can_send_acl_packet_now(handle);
277     if (!can_send){
278         int index = l2cap_fixed_channel_table_index_for_channel_id(channel_id);
279         if (index >= 0){
280             fixed_channels[index].waiting_for_can_send_now = 1;
281         }
282     }
283     return can_send;
284 }
285 
286 uint16_t l2cap_get_remote_mtu_for_local_cid(uint16_t local_cid){
287     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
288     if (channel) {
289         return channel->remote_mtu;
290     }
291     return 0;
292 }
293 
294 static l2cap_channel_t * l2cap_channel_for_rtx_timer(btstack_timer_source_t * ts){
295     btstack_linked_list_iterator_t it;
296     btstack_linked_list_iterator_init(&it, &l2cap_channels);
297     while (btstack_linked_list_iterator_has_next(&it)){
298         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
299         if ( &channel->rtx == ts) {
300             return channel;
301         }
302     }
303     return NULL;
304 }
305 
306 static void l2cap_rtx_timeout(btstack_timer_source_t * ts){
307     l2cap_channel_t * channel = l2cap_channel_for_rtx_timer(ts);
308     if (!ts) return;
309 
310     log_info("l2cap_rtx_timeout for local cid 0x%02x", channel->local_cid);
311 
312     // "When terminating the channel, it is not necessary to send a L2CAP_DisconnectReq
313     //  and enter WAIT_DISCONNECT state. Channels can be transitioned directly to the CLOSED state."
314     // notify client
315     l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_RTX_TIMEOUT);
316 
317     // discard channel
318     // no need to stop timer here, it is removed from list during timer callback
319     btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
320     btstack_memory_l2cap_channel_free(channel);
321 }
322 
323 static void l2cap_stop_rtx(l2cap_channel_t * channel){
324     log_info("l2cap_stop_rtx for local cid 0x%02x", channel->local_cid);
325     btstack_run_loop_remove_timer(&channel->rtx);
326 }
327 
328 static void l2cap_start_rtx(l2cap_channel_t * channel){
329     l2cap_stop_rtx(channel);
330     log_info("l2cap_start_rtx for local cid 0x%02x", channel->local_cid);
331     btstack_run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
332     btstack_run_loop_set_timer(&channel->rtx, L2CAP_RTX_TIMEOUT_MS);
333     btstack_run_loop_add_timer(&channel->rtx);
334 }
335 
336 static void l2cap_start_ertx(l2cap_channel_t * channel){
337     log_info("l2cap_start_ertx for local cid 0x%02x", channel->local_cid);
338     l2cap_stop_rtx(channel);
339     btstack_run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
340     btstack_run_loop_set_timer(&channel->rtx, L2CAP_ERTX_TIMEOUT_MS);
341     btstack_run_loop_add_timer(&channel->rtx);
342 }
343 
344 void l2cap_require_security_level_2_for_outgoing_sdp(void){
345     require_security_level2_for_outgoing_sdp = 1;
346 }
347 
348 static int l2cap_security_level_0_allowed_for_PSM(uint16_t psm){
349     return (psm == PSM_SDP) && (!require_security_level2_for_outgoing_sdp);
350 }
351 
352 static int l2cap_send_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
353 
354     if (!hci_can_send_acl_packet_now(handle)){
355         log_info("l2cap_send_signaling_packet, cannot send");
356         return BTSTACK_ACL_BUFFERS_FULL;
357     }
358 
359     // log_info("l2cap_send_signaling_packet type %u", cmd);
360     hci_reserve_packet_buffer();
361     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
362     va_list argptr;
363     va_start(argptr, identifier);
364     uint16_t len = l2cap_create_signaling_classic(acl_buffer, handle, cmd, identifier, argptr);
365     va_end(argptr);
366     // log_info("l2cap_send_signaling_packet con %u!", handle);
367     return hci_send_acl_packet_buffer(len);
368 }
369 
370 #ifdef ENABLE_BLE
371 static int l2cap_send_le_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
372 
373     if (!hci_can_send_acl_packet_now(handle)){
374         log_info("l2cap_send_signaling_packet, cannot send");
375         return BTSTACK_ACL_BUFFERS_FULL;
376     }
377 
378     // log_info("l2cap_send_signaling_packet type %u", cmd);
379     hci_reserve_packet_buffer();
380     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
381     va_list argptr;
382     va_start(argptr, identifier);
383     uint16_t len = l2cap_create_signaling_le(acl_buffer, handle, cmd, identifier, argptr);
384     va_end(argptr);
385     // log_info("l2cap_send_signaling_packet con %u!", handle);
386     return hci_send_acl_packet_buffer(len);
387 }
388 #endif
389 
390 uint8_t *l2cap_get_outgoing_buffer(void){
391     return hci_get_outgoing_packet_buffer() + COMPLETE_L2CAP_HEADER; // 8 bytes
392 }
393 
394 int l2cap_reserve_packet_buffer(void){
395     return hci_reserve_packet_buffer();
396 }
397 
398 void l2cap_release_packet_buffer(void){
399     hci_release_packet_buffer();
400 }
401 
402 
403 int l2cap_send_prepared(uint16_t local_cid, uint16_t len){
404 
405     if (!hci_is_packet_buffer_reserved()){
406         log_error("l2cap_send_prepared called without reserving packet first");
407         return BTSTACK_ACL_BUFFERS_FULL;
408     }
409 
410     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
411     if (!channel) {
412         log_error("l2cap_send_prepared no channel for cid 0x%02x", local_cid);
413         return -1;   // TODO: define error
414     }
415 
416     if (!hci_can_send_prepared_acl_packet_now(channel->handle)){
417         log_info("l2cap_send_prepared cid 0x%02x, cannot send", local_cid);
418         return BTSTACK_ACL_BUFFERS_FULL;
419     }
420 
421     log_debug("l2cap_send_prepared cid 0x%02x, handle %u, 1 credit used", local_cid, channel->handle);
422 
423     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
424 
425     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
426 
427     // 0 - Connection handle : PB=pb : BC=00
428     little_endian_store_16(acl_buffer, 0, channel->handle | (pb << 12) | (0 << 14));
429     // 2 - ACL length
430     little_endian_store_16(acl_buffer, 2,  len + 4);
431     // 4 - L2CAP packet length
432     little_endian_store_16(acl_buffer, 4,  len + 0);
433     // 6 - L2CAP channel DEST
434     little_endian_store_16(acl_buffer, 6, channel->remote_cid);
435     // send
436     int err = hci_send_acl_packet_buffer(len+8);
437 
438     return err;
439 }
440 
441 int l2cap_send_prepared_connectionless(uint16_t handle, uint16_t cid, uint16_t len){
442 
443     if (!hci_is_packet_buffer_reserved()){
444         log_error("l2cap_send_prepared_connectionless called without reserving packet first");
445         return BTSTACK_ACL_BUFFERS_FULL;
446     }
447 
448     if (!hci_can_send_prepared_acl_packet_now(handle)){
449         log_info("l2cap_send_prepared_connectionless handle 0x%02x, cid 0x%02x, cannot send", handle, cid);
450         return BTSTACK_ACL_BUFFERS_FULL;
451     }
452 
453     log_debug("l2cap_send_prepared_connectionless handle %u, cid 0x%02x", handle, cid);
454 
455     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
456 
457     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
458 
459     // 0 - Connection handle : PB=pb : BC=00
460     little_endian_store_16(acl_buffer, 0, handle | (pb << 12) | (0 << 14));
461     // 2 - ACL length
462     little_endian_store_16(acl_buffer, 2,  len + 4);
463     // 4 - L2CAP packet length
464     little_endian_store_16(acl_buffer, 4,  len + 0);
465     // 6 - L2CAP channel DEST
466     little_endian_store_16(acl_buffer, 6, cid);
467     // send
468     int err = hci_send_acl_packet_buffer(len+8);
469 
470     return err;
471 }
472 
473 int l2cap_send(uint16_t local_cid, uint8_t *data, uint16_t len){
474 
475     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
476     if (!channel) {
477         log_error("l2cap_send no channel for cid 0x%02x", local_cid);
478         return -1;   // TODO: define error
479     }
480 
481     if (len > channel->remote_mtu){
482         log_error("l2cap_send cid 0x%02x, data length exceeds remote MTU.", local_cid);
483         return L2CAP_DATA_LEN_EXCEEDS_REMOTE_MTU;
484     }
485 
486     if (!hci_can_send_acl_packet_now(channel->handle)){
487         log_info("l2cap_send cid 0x%02x, cannot send", local_cid);
488         return BTSTACK_ACL_BUFFERS_FULL;
489     }
490 
491     hci_reserve_packet_buffer();
492     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
493 
494     memcpy(&acl_buffer[8], data, len);
495 
496     return l2cap_send_prepared(local_cid, len);
497 }
498 
499 int l2cap_send_connectionless(uint16_t handle, uint16_t cid, uint8_t *data, uint16_t len){
500 
501     if (!hci_can_send_acl_packet_now(handle)){
502         log_info("l2cap_send cid 0x%02x, cannot send", cid);
503         return BTSTACK_ACL_BUFFERS_FULL;
504     }
505 
506     hci_reserve_packet_buffer();
507     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
508 
509     memcpy(&acl_buffer[8], data, len);
510 
511     return l2cap_send_prepared_connectionless(handle, cid, len);
512 }
513 
514 int l2cap_send_echo_request(uint16_t handle, uint8_t *data, uint16_t len){
515     return l2cap_send_signaling_packet(handle, ECHO_REQUEST, 0x77, len, data);
516 }
517 
518 static inline void channelStateVarSetFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
519     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var | flag);
520 }
521 
522 static inline void channelStateVarClearFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
523     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var & ~flag);
524 }
525 
526 
527 
528 // MARK: L2CAP_RUN
529 // process outstanding signaling tasks
530 static void l2cap_run(void){
531 
532     // log_info("l2cap_run: entered");
533 
534     // check pending signaling responses
535     while (signaling_responses_pending){
536 
537         hci_con_handle_t handle = signaling_responses[0].handle;
538 
539         if (!hci_can_send_acl_packet_now(handle)) break;
540 
541         uint8_t  sig_id = signaling_responses[0].sig_id;
542         uint16_t infoType = signaling_responses[0].data;    // INFORMATION_REQUEST
543         uint16_t result   = signaling_responses[0].data;    // CONNECTION_REQUEST, COMMAND_REJECT
544         uint8_t  response_code = signaling_responses[0].code;
545 
546         // remove first item before sending (to avoid sending response mutliple times)
547         signaling_responses_pending--;
548         int i;
549         for (i=0; i < signaling_responses_pending; i++){
550             memcpy(&signaling_responses[i], &signaling_responses[i+1], sizeof(l2cap_signaling_response_t));
551         }
552 
553         switch (response_code){
554             case CONNECTION_REQUEST:
555                 l2cap_send_signaling_packet(handle, CONNECTION_RESPONSE, sig_id, 0, 0, result, 0);
556                 // also disconnect if result is 0x0003 - security blocked
557                 if (result == 0x0003){
558                     hci_disconnect_security_block(handle);
559                 }
560                 break;
561             case ECHO_REQUEST:
562                 l2cap_send_signaling_packet(handle, ECHO_RESPONSE, sig_id, 0, NULL);
563                 break;
564             case INFORMATION_REQUEST:
565                 switch (infoType){
566                     case 1: { // Connectionless MTU
567                         uint16_t connectionless_mtu = hci_max_acl_data_packet_length();
568                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(connectionless_mtu), &connectionless_mtu);
569                         break;
570                     }
571                     case 2: { // Extended Features Supported
572                         // extended features request supported, features: fixed channels, unicast connectionless data reception
573                         uint32_t features = 0x280;
574                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(features), &features);
575                         break;
576                     }
577                     case 3: { // Fixed Channels Supported
578                         uint8_t map[8];
579                         memset(map, 0, 8);
580                         map[0] = 0x01;  // L2CAP Signaling Channel (0x01) + Connectionless reception (0x02)
581                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(map), &map);
582                         break;
583                     }
584                     default:
585                         // all other types are not supported
586                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 1, 0, NULL);
587                         break;
588                 }
589                 break;
590             case COMMAND_REJECT:
591                 l2cap_send_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
592 #ifdef ENABLE_BLE
593             case COMMAND_REJECT_LE:
594                 l2cap_send_le_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
595                 break;
596 #endif
597             default:
598                 // should not happen
599                 break;
600         }
601     }
602 
603     uint8_t  config_options[4];
604     btstack_linked_list_iterator_t it;
605     btstack_linked_list_iterator_init(&it, &l2cap_channels);
606     while (btstack_linked_list_iterator_has_next(&it)){
607 
608         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
609         // log_info("l2cap_run: channel %p, state %u, var 0x%02x", channel, channel->state, channel->state_var);
610         switch (channel->state){
611 
612             case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
613             case L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT:
614                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
615                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND) {
616                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND);
617                     l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 1, 0);
618                 }
619                 break;
620 
621             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
622                 if (!hci_can_send_command_packet_now()) break;
623                 // send connection request - set state first
624                 channel->state = L2CAP_STATE_WAIT_CONNECTION_COMPLETE;
625                 // BD_ADDR, Packet_Type, Page_Scan_Repetition_Mode, Reserved, Clock_Offset, Allow_Role_Switch
626                 hci_send_cmd(&hci_create_connection, channel->address, hci_usable_acl_packet_types(), 0, 0, 0, 1);
627                 break;
628 
629             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE:
630                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
631                 channel->state = L2CAP_STATE_INVALID;
632                 l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, channel->reason, 0);
633                 // discard channel - l2cap_finialize_channel_close without sending l2cap close event
634                 l2cap_stop_rtx(channel);
635                 btstack_linked_list_iterator_remove(&it);
636                 btstack_memory_l2cap_channel_free(channel);
637                 break;
638 
639             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT:
640                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
641                 channel->state = L2CAP_STATE_CONFIG;
642                 channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
643                 l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 0, 0);
644                 break;
645 
646             case L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST:
647                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
648                 // success, start l2cap handshake
649                 channel->local_sig_id = l2cap_next_sig_id();
650                 channel->state = L2CAP_STATE_WAIT_CONNECT_RSP;
651                 l2cap_send_signaling_packet( channel->handle, CONNECTION_REQUEST, channel->local_sig_id, channel->psm, channel->local_cid);
652                 l2cap_start_rtx(channel);
653                 break;
654 
655             case L2CAP_STATE_CONFIG:
656                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
657                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP){
658                     uint16_t flags = 0;
659                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
660                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT) {
661                         flags = 1;
662                     } else {
663                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP);
664                     }
665                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID){
666                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, L2CAP_CONF_RESULT_UNKNOWN_OPTIONS, 0, NULL);
667                     } else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU){
668                         config_options[0] = 1; // MTU
669                         config_options[1] = 2; // len param
670                         little_endian_store_16( (uint8_t*)&config_options, 2, channel->remote_mtu);
671                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 4, &config_options);
672                         channelStateVarClearFlag(channel,L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
673                     } else {
674                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 0, NULL);
675                     }
676                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
677                 }
678                 else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ){
679                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
680                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_REQ);
681                     channel->local_sig_id = l2cap_next_sig_id();
682                     config_options[0] = 1; // MTU
683                     config_options[1] = 2; // len param
684                     little_endian_store_16( (uint8_t*)&config_options, 2, channel->local_mtu);
685                     l2cap_send_signaling_packet(channel->handle, CONFIGURE_REQUEST, channel->local_sig_id, channel->remote_cid, 0, 4, &config_options);
686                     l2cap_start_rtx(channel);
687                 }
688                 if (l2cap_channel_ready_for_open(channel)){
689                     channel->state = L2CAP_STATE_OPEN;
690                     l2cap_emit_channel_opened(channel, 0);  // success
691                 }
692                 break;
693 
694             case L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE:
695                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
696                 channel->state = L2CAP_STATE_INVALID;
697                 l2cap_send_signaling_packet( channel->handle, DISCONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid);
698                 // we don't start an RTX timer for a disconnect - there's no point in closing the channel if the other side doesn't respond :)
699                 l2cap_finialize_channel_close(channel);  // -- remove from list
700                 break;
701 
702             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
703                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
704                 channel->local_sig_id = l2cap_next_sig_id();
705                 channel->state = L2CAP_STATE_WAIT_DISCONNECT;
706                 l2cap_send_signaling_packet( channel->handle, DISCONNECTION_REQUEST, channel->local_sig_id, channel->remote_cid, channel->local_cid);
707                 break;
708             default:
709                 break;
710         }
711     }
712 
713 #ifdef ENABLE_BLE
714     // send l2cap con paramter update if necessary
715     hci_connections_get_iterator(&it);
716     while(btstack_linked_list_iterator_has_next(&it)){
717         hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it);
718         if (connection->address_type != BD_ADDR_TYPE_LE_PUBLIC && connection->address_type != BD_ADDR_TYPE_LE_RANDOM) continue;
719         if (!hci_can_send_acl_packet_now(connection->con_handle)) continue;
720         switch (connection->le_con_parameter_update_state){
721             case CON_PARAMETER_UPDATE_SEND_REQUEST:
722                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_NONE;
723                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_REQUEST, connection->le_con_param_update_identifier,
724                                                connection->le_conn_interval_min, connection->le_conn_interval_max, connection->le_conn_latency, connection->le_supervision_timeout);
725                 break;
726             case CON_PARAMETER_UPDATE_SEND_RESPONSE:
727                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_CHANGE_HCI_CON_PARAMETERS;
728                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_RESPONSE, connection->le_con_param_update_identifier, 0);
729                 break;
730             case CON_PARAMETER_UPDATE_DENY:
731                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_NONE;
732                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_RESPONSE, connection->le_con_param_update_identifier, 1);
733                 break;
734             default:
735                 break;
736         }
737     }
738 #endif
739 
740     // log_info("l2cap_run: exit");
741 }
742 
743 uint16_t l2cap_max_mtu(void){
744     return HCI_ACL_PAYLOAD_SIZE - L2CAP_HEADER_SIZE;
745 }
746 
747 uint16_t l2cap_max_le_mtu(void){
748     return l2cap_max_mtu();
749 }
750 
751 static void l2cap_handle_connection_complete(uint16_t handle, l2cap_channel_t * channel){
752     if (channel->state == L2CAP_STATE_WAIT_CONNECTION_COMPLETE || channel->state == L2CAP_STATE_WILL_SEND_CREATE_CONNECTION) {
753         log_info("l2cap_handle_connection_complete expected state");
754         // success, start l2cap handshake
755         channel->handle = handle;
756         // check remote SSP feature first
757         channel->state = L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES;
758     }
759 }
760 
761 static void l2cap_handle_remote_supported_features_received(l2cap_channel_t * channel){
762     if (channel->state != L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES) return;
763 
764     // we have been waiting for remote supported features, if both support SSP,
765     log_info("l2cap received remote supported features, sec_level_0_allowed for psm %u = %u", channel->psm, l2cap_security_level_0_allowed_for_PSM(channel->psm));
766     if (hci_ssp_supported_on_both_sides(channel->handle) && !l2cap_security_level_0_allowed_for_PSM(channel->psm)){
767         // request security level 2
768         channel->state = L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE;
769         gap_request_security_level(channel->handle, LEVEL_2);
770         return;
771     }
772     // fine, go ahead
773     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
774 }
775 
776 /**
777  * @brief Creates L2CAP channel to the PSM of a remote device with baseband address. A new baseband connection will be initiated if necessary.
778  * @param packet_handler
779  * @param address
780  * @param psm
781  * @param mtu
782  * @param local_cid
783  */
784 uint8_t l2cap_create_channel(btstack_packet_handler_t channel_packet_handler, bd_addr_t address, uint16_t psm, uint16_t mtu, uint16_t * out_local_cid){
785     log_info("L2CAP_CREATE_CHANNEL addr %s psm 0x%x mtu %u", bd_addr_to_str(address), psm, mtu);
786 
787     // alloc structure
788     l2cap_channel_t * chan = btstack_memory_l2cap_channel_get();
789     if (!chan) {
790         return BTSTACK_MEMORY_ALLOC_FAILED;
791     }
792 
793      // Init memory (make valgrind happy)
794     memset(chan, 0, sizeof(l2cap_channel_t));
795     // limit local mtu to max acl packet length - l2cap header
796     if (mtu > l2cap_max_mtu()) {
797         mtu = l2cap_max_mtu();
798     }
799 
800     // fill in
801     bd_addr_copy(chan->address, address);
802     chan->psm = psm;
803     chan->handle = 0;
804     chan->packet_handler = channel_packet_handler;
805     chan->remote_mtu = L2CAP_MINIMAL_MTU;
806     chan->local_mtu = mtu;
807     chan->local_cid = l2cap_next_local_cid();
808 
809     // set initial state
810     chan->state = L2CAP_STATE_WILL_SEND_CREATE_CONNECTION;
811     chan->state_var = L2CAP_CHANNEL_STATE_VAR_NONE;
812     chan->remote_sig_id = L2CAP_SIG_ID_INVALID;
813     chan->local_sig_id = L2CAP_SIG_ID_INVALID;
814     chan->required_security_level = LEVEL_0;
815 
816     // add to connections list
817     btstack_linked_list_add(&l2cap_channels, (btstack_linked_item_t *) chan);
818 
819     // store local_cid
820     if (out_local_cid){
821        *out_local_cid = chan->local_cid;
822     }
823 
824     // check if hci connection is already usable
825     hci_connection_t * conn = hci_connection_for_bd_addr_and_type(address, BD_ADDR_TYPE_CLASSIC);
826     if (conn){
827         log_info("l2cap_create_channel, hci connection already exists");
828         l2cap_handle_connection_complete(conn->con_handle, chan);
829         // check if remote supported fearures are already received
830         if (conn->bonding_flags & BONDING_RECEIVED_REMOTE_FEATURES) {
831             l2cap_handle_remote_supported_features_received(chan);
832         }
833     }
834 
835     l2cap_run();
836 
837     return 0;
838 }
839 
840 void
841 l2cap_disconnect(uint16_t local_cid, uint8_t reason){
842     log_info("L2CAP_DISCONNECT local_cid 0x%x reason 0x%x", local_cid, reason);
843     // find channel for local_cid
844     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
845     if (channel) {
846         channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST;
847     }
848     // process
849     l2cap_run();
850 }
851 
852 static void l2cap_handle_connection_failed_for_addr(bd_addr_t address, uint8_t status){
853     btstack_linked_list_iterator_t it;
854     btstack_linked_list_iterator_init(&it, &l2cap_channels);
855     while (btstack_linked_list_iterator_has_next(&it)){
856         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
857         if ( bd_addr_cmp( channel->address, address) != 0) continue;
858         // channel for this address found
859         switch (channel->state){
860             case L2CAP_STATE_WAIT_CONNECTION_COMPLETE:
861             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
862                 // failure, forward error code
863                 l2cap_emit_channel_opened(channel, status);
864                 // discard channel
865                 l2cap_stop_rtx(channel);
866                 btstack_linked_list_iterator_remove(&it);
867                 btstack_memory_l2cap_channel_free(channel);
868                 break;
869             default:
870                 break;
871         }
872     }
873 }
874 
875 static void l2cap_handle_connection_success_for_addr(bd_addr_t address, hci_con_handle_t handle){
876     btstack_linked_list_iterator_t it;
877     btstack_linked_list_iterator_init(&it, &l2cap_channels);
878     while (btstack_linked_list_iterator_has_next(&it)){
879         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
880         if ( ! bd_addr_cmp( channel->address, address) ){
881             l2cap_handle_connection_complete(handle, channel);
882         }
883     }
884     // process
885     l2cap_run();
886 }
887 
888 static void l2cap_notify_channel_can_send(void){
889     btstack_linked_list_iterator_t it;
890     btstack_linked_list_iterator_init(&it, &l2cap_channels);
891     while (btstack_linked_list_iterator_has_next(&it)){
892         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
893         if (!channel->waiting_for_can_send_now) continue;
894         if (!hci_can_send_acl_packet_now(channel->handle)) continue;
895         channel->waiting_for_can_send_now = 0;
896         l2cap_emit_can_send_now(channel->packet_handler, channel->local_cid);
897     }
898 
899     int i;
900     for (i=0;i<L2CAP_FIXED_CHANNEL_TABLE_SIZE;i++){
901         if (!fixed_channels[i].callback) continue;
902         if (!fixed_channels[i].waiting_for_can_send_now) continue;
903         int can_send;
904         if (l2cap_fixed_channel_table_index_is_le(i)){
905             can_send = hci_can_send_acl_le_packet_now();
906         } else {
907             can_send = hci_can_send_acl_classic_packet_now();
908         }
909         if (!can_send) continue;
910         fixed_channels[i].waiting_for_can_send_now = 0;
911         l2cap_emit_can_send_now(fixed_channels[i].callback, l2cap_fixed_channel_table_channel_id_for_index(i));
912     }
913 }
914 
915 static void l2cap_hci_event_handler(uint8_t packet_type, uint16_t cid, uint8_t *packet, uint16_t size){
916 
917     bd_addr_t address;
918     hci_con_handle_t handle;
919     btstack_linked_list_iterator_t it;
920     int hci_con_used;
921 
922     switch(packet[0]){
923 
924         // handle connection complete events
925         case HCI_EVENT_CONNECTION_COMPLETE:
926             reverse_bd_addr(&packet[5], address);
927             if (packet[2] == 0){
928                 handle = little_endian_read_16(packet, 3);
929                 l2cap_handle_connection_success_for_addr(address, handle);
930             } else {
931                 l2cap_handle_connection_failed_for_addr(address, packet[2]);
932             }
933             break;
934 
935         // handle successful create connection cancel command
936         case HCI_EVENT_COMMAND_COMPLETE:
937             if (HCI_EVENT_IS_COMMAND_COMPLETE(packet, hci_create_connection_cancel)) {
938                 if (packet[5] == 0){
939                     reverse_bd_addr(&packet[6], address);
940                     // CONNECTION TERMINATED BY LOCAL HOST (0X16)
941                     l2cap_handle_connection_failed_for_addr(address, 0x16);
942                 }
943             }
944             l2cap_run();    // try sending signaling packets first
945             break;
946 
947         case HCI_EVENT_COMMAND_STATUS:
948             l2cap_run();    // try sending signaling packets first
949             break;
950 
951         // handle disconnection complete events
952         case HCI_EVENT_DISCONNECTION_COMPLETE:
953             // send l2cap disconnect events for all channels on this handle and free them
954             handle = little_endian_read_16(packet, 3);
955             btstack_linked_list_iterator_init(&it, &l2cap_channels);
956             while (btstack_linked_list_iterator_has_next(&it)){
957                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
958                 if (channel->handle != handle) continue;
959                 l2cap_emit_channel_closed(channel);
960                 l2cap_stop_rtx(channel);
961                 btstack_linked_list_iterator_remove(&it);
962                 btstack_memory_l2cap_channel_free(channel);
963             }
964             break;
965 
966         // Notify channel packet handler if they can send now
967         case DAEMON_EVENT_HCI_PACKET_SENT:
968         case HCI_EVENT_NUMBER_OF_COMPLETED_PACKETS:
969             l2cap_run();    // try sending signaling packets first
970             l2cap_notify_channel_can_send();
971             break;
972 
973         // HCI Connection Timeouts
974         case L2CAP_EVENT_TIMEOUT_CHECK:
975             handle = little_endian_read_16(packet, 2);
976             if (gap_get_connection_type(handle) != GAP_CONNECTION_ACL) break;
977             if (hci_authentication_active_for_handle(handle)) break;
978             hci_con_used = 0;
979             btstack_linked_list_iterator_init(&it, &l2cap_channels);
980             while (btstack_linked_list_iterator_has_next(&it)){
981                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
982                 if (channel->handle != handle) continue;
983                 hci_con_used = 1;
984                 break;
985             }
986             if (hci_con_used) break;
987             if (!hci_can_send_command_packet_now()) break;
988             hci_send_cmd(&hci_disconnect, handle, 0x13); // remote closed connection
989             break;
990 
991         case HCI_EVENT_READ_REMOTE_SUPPORTED_FEATURES_COMPLETE:
992             handle = little_endian_read_16(packet, 3);
993             btstack_linked_list_iterator_init(&it, &l2cap_channels);
994             while (btstack_linked_list_iterator_has_next(&it)){
995                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
996                 if (channel->handle != handle) continue;
997                 l2cap_handle_remote_supported_features_received(channel);
998                 break;
999             }
1000             break;
1001 
1002         case GAP_EVENT_SECURITY_LEVEL:
1003             handle = little_endian_read_16(packet, 2);
1004             log_info("l2cap - security level update");
1005             btstack_linked_list_iterator_init(&it, &l2cap_channels);
1006             while (btstack_linked_list_iterator_has_next(&it)){
1007                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
1008                 if (channel->handle != handle) continue;
1009 
1010                 log_info("l2cap - state %u", channel->state);
1011 
1012                 gap_security_level_t actual_level = (gap_security_level_t) packet[4];
1013                 gap_security_level_t required_level = channel->required_security_level;
1014 
1015                 switch (channel->state){
1016                     case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
1017                         if (actual_level >= required_level){
1018                             channel->state = L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT;
1019                             l2cap_emit_connection_request(channel);
1020                         } else {
1021                             channel->reason = 0x0003; // security block
1022                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
1023                         }
1024                         break;
1025 
1026                     case L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE:
1027                         if (actual_level >= required_level){
1028                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
1029                         } else {
1030                             // disconnnect, authentication not good enough
1031                             hci_disconnect_security_block(handle);
1032                         }
1033                         break;
1034 
1035                     default:
1036                         break;
1037                 }
1038             }
1039             break;
1040 
1041         default:
1042             break;
1043     }
1044 
1045     l2cap_run();
1046 }
1047 
1048 static void l2cap_handle_disconnect_request(l2cap_channel_t *channel, uint16_t identifier){
1049     channel->remote_sig_id = identifier;
1050     channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE;
1051     l2cap_run();
1052 }
1053 
1054 static void l2cap_register_signaling_response(hci_con_handle_t handle, uint8_t code, uint8_t sig_id, uint16_t data){
1055     // Vol 3, Part A, 4.3: "The DCID and SCID fields shall be ignored when the result field indi- cates the connection was refused."
1056     if (signaling_responses_pending < NR_PENDING_SIGNALING_RESPONSES) {
1057         signaling_responses[signaling_responses_pending].handle = handle;
1058         signaling_responses[signaling_responses_pending].code = code;
1059         signaling_responses[signaling_responses_pending].sig_id = sig_id;
1060         signaling_responses[signaling_responses_pending].data = data;
1061         signaling_responses_pending++;
1062         l2cap_run();
1063     }
1064 }
1065 
1066 static void l2cap_handle_connection_request(hci_con_handle_t handle, uint8_t sig_id, uint16_t psm, uint16_t source_cid){
1067 
1068     // log_info("l2cap_handle_connection_request for handle %u, psm %u cid 0x%02x", handle, psm, source_cid);
1069     l2cap_service_t *service = l2cap_get_service(psm);
1070     if (!service) {
1071         // 0x0002 PSM not supported
1072         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0002);
1073         return;
1074     }
1075 
1076     hci_connection_t * hci_connection = hci_connection_for_handle( handle );
1077     if (!hci_connection) {
1078         //
1079         log_error("no hci_connection for handle %u", handle);
1080         return;
1081     }
1082 
1083     // alloc structure
1084     // log_info("l2cap_handle_connection_request register channel");
1085     l2cap_channel_t * channel = btstack_memory_l2cap_channel_get();
1086     if (!channel){
1087         // 0x0004 No resources available
1088         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0004);
1089         return;
1090     }
1091     // Init memory (make valgrind happy)
1092     memset(channel, 0, sizeof(l2cap_channel_t));
1093     // fill in
1094     bd_addr_copy(channel->address, hci_connection->address);
1095     channel->psm = psm;
1096     channel->handle = handle;
1097     channel->packet_handler = service->packet_handler;
1098     channel->local_cid  = l2cap_next_local_cid();
1099     channel->remote_cid = source_cid;
1100     channel->local_mtu  = service->mtu;
1101     channel->remote_mtu = L2CAP_DEFAULT_MTU;
1102     channel->remote_sig_id = sig_id;
1103     channel->required_security_level = service->required_security_level;
1104 
1105     // limit local mtu to max acl packet length - l2cap header
1106     if (channel->local_mtu > l2cap_max_mtu()) {
1107         channel->local_mtu = l2cap_max_mtu();
1108     }
1109 
1110     // set initial state
1111     channel->state =     L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE;
1112     channel->state_var = L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND;
1113 
1114     // add to connections list
1115     btstack_linked_list_add(&l2cap_channels, (btstack_linked_item_t *) channel);
1116 
1117     // assert security requirements
1118     gap_request_security_level(handle, channel->required_security_level);
1119 }
1120 
1121 void l2cap_accept_connection(uint16_t local_cid){
1122     log_info("L2CAP_ACCEPT_CONNECTION local_cid 0x%x", local_cid);
1123     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
1124     if (!channel) {
1125         log_error("l2cap_accept_connection called but local_cid 0x%x not found", local_cid);
1126         return;
1127     }
1128 
1129     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT;
1130 
1131     // process
1132     l2cap_run();
1133 }
1134 
1135 void l2cap_decline_connection(uint16_t local_cid, uint8_t reason){
1136     log_info("L2CAP_DECLINE_CONNECTION local_cid 0x%x, reason %x", local_cid, reason);
1137     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid( local_cid);
1138     if (!channel) {
1139         log_error( "l2cap_decline_connection called but local_cid 0x%x not found", local_cid);
1140         return;
1141     }
1142     channel->state  = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
1143     channel->reason = reason;
1144     l2cap_run();
1145 }
1146 
1147 static void l2cap_signaling_handle_configure_request(l2cap_channel_t *channel, uint8_t *command){
1148 
1149     channel->remote_sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1150 
1151     uint16_t flags = little_endian_read_16(command, 6);
1152     if (flags & 1) {
1153         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
1154     }
1155 
1156     // accept the other's configuration options
1157     uint16_t end_pos = 4 + little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1158     uint16_t pos     = 8;
1159     while (pos < end_pos){
1160         uint8_t option_hint = command[pos] >> 7;
1161         uint8_t option_type = command[pos] & 0x7f;
1162         log_info("l2cap cid %u, hint %u, type %u", channel->local_cid, option_hint, option_type);
1163         pos++;
1164         uint8_t length = command[pos++];
1165         // MTU { type(8): 1, len(8):2, MTU(16) }
1166         if (option_type == 1 && length == 2){
1167             channel->remote_mtu = little_endian_read_16(command, pos);
1168             // log_info("l2cap cid 0x%02x, remote mtu %u", channel->local_cid, channel->remote_mtu);
1169             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
1170         }
1171         // Flush timeout { type(8):2, len(8): 2, Flush Timeout(16)}
1172         if (option_type == 2 && length == 2){
1173             channel->flush_timeout = little_endian_read_16(command, pos);
1174         }
1175         // check for unknown options
1176         if (option_hint == 0 && (option_type == 0 || option_type >= 0x07)){
1177             log_info("l2cap cid %u, unknown options", channel->local_cid);
1178             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID);
1179         }
1180         pos += length;
1181     }
1182 }
1183 
1184 static int l2cap_channel_ready_for_open(l2cap_channel_t *channel){
1185     // log_info("l2cap_channel_ready_for_open 0x%02x", channel->state_var);
1186     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP) == 0) return 0;
1187     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP) == 0) return 0;
1188     // addition check that fixes re-entrance issue causing l2cap event channel opened twice
1189     if (channel->state == L2CAP_STATE_OPEN) return 0;
1190     return 1;
1191 }
1192 
1193 
1194 static void l2cap_signaling_handler_channel(l2cap_channel_t *channel, uint8_t *command){
1195 
1196     uint8_t  code       = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1197     uint8_t  identifier = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1198     uint16_t result = 0;
1199 
1200     log_info("L2CAP signaling handler code %u, state %u", code, channel->state);
1201 
1202     // handle DISCONNECT REQUESTS seperately
1203     if (code == DISCONNECTION_REQUEST){
1204         switch (channel->state){
1205             case L2CAP_STATE_CONFIG:
1206             case L2CAP_STATE_OPEN:
1207             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
1208             case L2CAP_STATE_WAIT_DISCONNECT:
1209                 l2cap_handle_disconnect_request(channel, identifier);
1210                 break;
1211 
1212             default:
1213                 // ignore in other states
1214                 break;
1215         }
1216         return;
1217     }
1218 
1219     // @STATEMACHINE(l2cap)
1220     switch (channel->state) {
1221 
1222         case L2CAP_STATE_WAIT_CONNECT_RSP:
1223             switch (code){
1224                 case CONNECTION_RESPONSE:
1225                     l2cap_stop_rtx(channel);
1226                     result = little_endian_read_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1227                     switch (result) {
1228                         case 0:
1229                             // successful connection
1230                             channel->remote_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1231                             channel->state = L2CAP_STATE_CONFIG;
1232                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1233                             break;
1234                         case 1:
1235                             // connection pending. get some coffee, but start the ERTX
1236                             l2cap_start_ertx(channel);
1237                             break;
1238                         default:
1239                             // channel closed
1240                             channel->state = L2CAP_STATE_CLOSED;
1241                             // map l2cap connection response result to BTstack status enumeration
1242                             l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result);
1243 
1244                             // drop link key if security block
1245                             if (L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result == L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_SECURITY){
1246                                 hci_drop_link_key_for_bd_addr(channel->address);
1247                             }
1248 
1249                             // discard channel
1250                             btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
1251                             btstack_memory_l2cap_channel_free(channel);
1252                             break;
1253                     }
1254                     break;
1255 
1256                 default:
1257                     //@TODO: implement other signaling packets
1258                     break;
1259             }
1260             break;
1261 
1262         case L2CAP_STATE_CONFIG:
1263             result = little_endian_read_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1264             switch (code) {
1265                 case CONFIGURE_REQUEST:
1266                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
1267                     l2cap_signaling_handle_configure_request(channel, command);
1268                     if (!(channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT)){
1269                         // only done if continuation not set
1270                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_REQ);
1271                     }
1272                     break;
1273                 case CONFIGURE_RESPONSE:
1274                     l2cap_stop_rtx(channel);
1275                     switch (result){
1276                         case 0: // success
1277                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP);
1278                             break;
1279                         case 4: // pending
1280                             l2cap_start_ertx(channel);
1281                             break;
1282                         default:
1283                             // retry on negative result
1284                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1285                             break;
1286                     }
1287                     break;
1288                 default:
1289                     break;
1290             }
1291             if (l2cap_channel_ready_for_open(channel)){
1292                 // for open:
1293                 channel->state = L2CAP_STATE_OPEN;
1294                 l2cap_emit_channel_opened(channel, 0);
1295             }
1296             break;
1297 
1298         case L2CAP_STATE_WAIT_DISCONNECT:
1299             switch (code) {
1300                 case DISCONNECTION_RESPONSE:
1301                     l2cap_finialize_channel_close(channel);
1302                     break;
1303                 default:
1304                     //@TODO: implement other signaling packets
1305                     break;
1306             }
1307             break;
1308 
1309         case L2CAP_STATE_CLOSED:
1310             // @TODO handle incoming requests
1311             break;
1312 
1313         case L2CAP_STATE_OPEN:
1314             //@TODO: implement other signaling packets, e.g. re-configure
1315             break;
1316         default:
1317             break;
1318     }
1319     // log_info("new state %u", channel->state);
1320 }
1321 
1322 
1323 static void l2cap_signaling_handler_dispatch( hci_con_handle_t handle, uint8_t * command){
1324 
1325     // get code, signalind identifier and command len
1326     uint8_t code   = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1327     uint8_t sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1328 
1329     // not for a particular channel, and not CONNECTION_REQUEST, ECHO_[REQUEST|RESPONSE], INFORMATION_REQUEST
1330     if (code < 1 || code == ECHO_RESPONSE || code > INFORMATION_REQUEST){
1331         l2cap_register_signaling_response(handle, COMMAND_REJECT, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1332         return;
1333     }
1334 
1335     // general commands without an assigned channel
1336     switch(code) {
1337 
1338         case CONNECTION_REQUEST: {
1339             uint16_t psm =        little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1340             uint16_t source_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+2);
1341             l2cap_handle_connection_request(handle, sig_id, psm, source_cid);
1342             return;
1343         }
1344 
1345         case ECHO_REQUEST:
1346             l2cap_register_signaling_response(handle, code, sig_id, 0);
1347             return;
1348 
1349         case INFORMATION_REQUEST: {
1350             uint16_t infoType = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1351             l2cap_register_signaling_response(handle, code, sig_id, infoType);
1352             return;
1353         }
1354 
1355         default:
1356             break;
1357     }
1358 
1359 
1360     // Get potential destination CID
1361     uint16_t dest_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1362 
1363     // Find channel for this sig_id and connection handle
1364     btstack_linked_list_iterator_t it;
1365     btstack_linked_list_iterator_init(&it, &l2cap_channels);
1366     while (btstack_linked_list_iterator_has_next(&it)){
1367         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
1368         if (channel->handle != handle) continue;
1369         if (code & 1) {
1370             // match odd commands (responses) by previous signaling identifier
1371             if (channel->local_sig_id == sig_id) {
1372                 l2cap_signaling_handler_channel(channel, command);
1373                 break;
1374             }
1375         } else {
1376             // match even commands (requests) by local channel id
1377             if (channel->local_cid == dest_cid) {
1378                 l2cap_signaling_handler_channel(channel, command);
1379                 break;
1380             }
1381         }
1382     }
1383 }
1384 
1385 static void l2cap_acl_handler(uint8_t packet_type, uint8_t *packet, uint16_t size ){
1386 
1387     // Get Channel ID
1388     uint16_t channel_id = READ_L2CAP_CHANNEL_ID(packet);
1389     hci_con_handle_t handle = READ_ACL_CONNECTION_HANDLE(packet);
1390 
1391     switch (channel_id) {
1392 
1393         case L2CAP_CID_SIGNALING: {
1394 
1395             uint16_t command_offset = 8;
1396             while (command_offset < size) {
1397 
1398                 // handle signaling commands
1399                 l2cap_signaling_handler_dispatch(handle, &packet[command_offset]);
1400 
1401                 // increment command_offset
1402                 command_offset += L2CAP_SIGNALING_COMMAND_DATA_OFFSET + little_endian_read_16(packet, command_offset + L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1403             }
1404             break;
1405         }
1406 
1407         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
1408             if (fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL].callback) {
1409                 (*fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL].callback)(ATT_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1410             }
1411             break;
1412 
1413         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
1414             if (fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL].callback) {
1415                 (*fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL].callback)(SM_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1416             }
1417             break;
1418 
1419         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
1420             if (fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL].callback) {
1421                 (*fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL].callback)(UCD_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1422             }
1423             break;
1424 
1425         case L2CAP_CID_SIGNALING_LE: {
1426             switch (packet[8]){
1427                 case CONNECTION_PARAMETER_UPDATE_RESPONSE: {
1428                     uint16_t result = little_endian_read_16(packet, 12);
1429                     l2cap_emit_connection_parameter_update_response(handle, result);
1430                     break;
1431                 }
1432                 case CONNECTION_PARAMETER_UPDATE_REQUEST: {
1433                     uint8_t event[10];
1434                     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_REQUEST;
1435                     event[1] = 8;
1436                     memcpy(&event[2], &packet[12], 8);
1437 
1438                     hci_connection_t * connection = hci_connection_for_handle(handle);
1439                     if (connection){
1440                         if (connection->role != HCI_ROLE_MASTER){
1441                             // reject command without notifying upper layer when not in master role
1442                             uint8_t sig_id = packet[COMPLETE_L2CAP_HEADER + 1];
1443                             l2cap_register_signaling_response(handle, COMMAND_REJECT_LE, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1444                             break;
1445                         }
1446                         int update_parameter = 1;
1447                         le_connection_parameter_range_t existing_range;
1448                         gap_get_connection_parameter_range(existing_range);
1449                         uint16_t le_conn_interval_min = little_endian_read_16(packet,12);
1450                         uint16_t le_conn_interval_max = little_endian_read_16(packet,14);
1451                         uint16_t le_conn_latency = little_endian_read_16(packet,16);
1452                         uint16_t le_supervision_timeout = little_endian_read_16(packet,18);
1453 
1454                         if (le_conn_interval_min < existing_range.le_conn_interval_min) update_parameter = 0;
1455                         if (le_conn_interval_max > existing_range.le_conn_interval_max) update_parameter = 0;
1456 
1457                         if (le_conn_latency < existing_range.le_conn_latency_min) update_parameter = 0;
1458                         if (le_conn_latency > existing_range.le_conn_latency_max) update_parameter = 0;
1459 
1460                         if (le_supervision_timeout < existing_range.le_supervision_timeout_min) update_parameter = 0;
1461                         if (le_supervision_timeout > existing_range.le_supervision_timeout_max) update_parameter = 0;
1462 
1463                         if (update_parameter){
1464                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_SEND_RESPONSE;
1465                             connection->le_conn_interval_min = le_conn_interval_min;
1466                             connection->le_conn_interval_max = le_conn_interval_max;
1467                             connection->le_conn_latency = le_conn_latency;
1468                             connection->le_supervision_timeout = le_supervision_timeout;
1469                         } else {
1470                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_DENY;
1471                         }
1472                         connection->le_con_param_update_identifier = packet[COMPLETE_L2CAP_HEADER + 1];
1473                     }
1474 
1475                     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
1476                     if (!l2cap_event_packet_handler) break;
1477                     (*l2cap_event_packet_handler)( HCI_EVENT_PACKET, 0, event, sizeof(event));
1478                     break;
1479                 }
1480                 default: {
1481                     uint8_t sig_id = packet[COMPLETE_L2CAP_HEADER + 1];
1482                     l2cap_register_signaling_response(handle, COMMAND_REJECT_LE, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1483                     break;
1484                 }
1485             }
1486             break;
1487         }
1488 
1489         default: {
1490             // Find channel for this channel_id and connection handle
1491             l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(channel_id);
1492             if (channel) {
1493                 l2cap_dispatch_to_channel(channel, L2CAP_DATA_PACKET, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1494             }
1495             break;
1496         }
1497     }
1498 
1499     l2cap_run();
1500 }
1501 
1502 // finalize closed channel - l2cap_handle_disconnect_request & DISCONNECTION_RESPONSE
1503 void l2cap_finialize_channel_close(l2cap_channel_t *channel){
1504     channel->state = L2CAP_STATE_CLOSED;
1505     l2cap_emit_channel_closed(channel);
1506     // discard channel
1507     l2cap_stop_rtx(channel);
1508     btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
1509     btstack_memory_l2cap_channel_free(channel);
1510 }
1511 
1512 static l2cap_service_t * l2cap_get_service_internal(btstack_linked_list_t * services, uint16_t psm){
1513     btstack_linked_list_iterator_t it;
1514     btstack_linked_list_iterator_init(&it, services);
1515     while (btstack_linked_list_iterator_has_next(&it)){
1516         l2cap_service_t * service = (l2cap_service_t *) btstack_linked_list_iterator_next(&it);
1517         if ( service->psm == psm){
1518             return service;
1519         };
1520     }
1521     return NULL;
1522 }
1523 
1524 static inline l2cap_service_t * l2cap_get_service(uint16_t psm){
1525     return l2cap_get_service_internal(&l2cap_services, psm);
1526 }
1527 
1528 
1529 uint8_t l2cap_register_service(btstack_packet_handler_t service_packet_handler, uint16_t psm, uint16_t mtu, gap_security_level_t security_level){
1530 
1531     log_info("L2CAP_REGISTER_SERVICE psm 0x%x mtu %u", psm, mtu);
1532 
1533     // check for alread registered psm
1534     // TODO: emit error event
1535     l2cap_service_t *service = l2cap_get_service(psm);
1536     if (service) {
1537         log_error("l2cap_register_service: PSM %u already registered", psm);
1538         return L2CAP_SERVICE_ALREADY_REGISTERED;
1539     }
1540 
1541     // alloc structure
1542     // TODO: emit error event
1543     service = btstack_memory_l2cap_service_get();
1544     if (!service) {
1545         log_error("l2cap_register_service: no memory for l2cap_service_t");
1546         return BTSTACK_MEMORY_ALLOC_FAILED;
1547     }
1548 
1549     // fill in
1550     service->psm = psm;
1551     service->mtu = mtu;
1552     service->packet_handler = service_packet_handler;
1553     service->required_security_level = security_level;
1554 
1555     // add to services list
1556     btstack_linked_list_add(&l2cap_services, (btstack_linked_item_t *) service);
1557 
1558     // enable page scan
1559     hci_connectable_control(1);
1560 
1561     return 0;
1562 }
1563 
1564 void l2cap_unregister_service(uint16_t psm){
1565 
1566     log_info("L2CAP_UNREGISTER_SERVICE psm 0x%x", psm);
1567 
1568     l2cap_service_t *service = l2cap_get_service(psm);
1569     if (!service) return;
1570     btstack_linked_list_remove(&l2cap_services, (btstack_linked_item_t *) service);
1571     btstack_memory_l2cap_service_free(service);
1572 
1573     // disable page scan when no services registered
1574     if (!btstack_linked_list_empty(&l2cap_services)) return;
1575     hci_connectable_control(0);
1576 }
1577 
1578 // Bluetooth 4.0 - allows to register handler for Attribute Protocol and Security Manager Protocol
1579 void l2cap_register_fixed_channel(btstack_packet_handler_t the_packet_handler, uint16_t channel_id) {
1580     int index = l2cap_fixed_channel_table_index_for_channel_id(channel_id);
1581     if (index < 0) return;
1582     fixed_channels[index].callback = the_packet_handler;
1583 }
1584 
1585 #ifdef ENABLE_BLE
1586 
1587 
1588 #if 0
1589 static inline l2cap_service_t * l2cap_le_get_service(uint16_t psm){
1590     return l2cap_get_service_internal(&l2cap_le_services, psm);
1591 }
1592 /**
1593  * @brief Regster L2CAP LE Credit Based Flow Control Mode service
1594  * @param
1595  */
1596 void l2cap_le_register_service(btstack_packet_handler_t packet_handler, uint16_t psm,
1597     uint16_t mtu, uint16_t mps, uint16_t initial_credits, gap_security_level_t security_level){
1598 
1599     log_info("L2CAP_LE_REGISTER_SERVICE psm 0x%x mtu %u connection %p", psm, mtu, connection);
1600 
1601     // check for alread registered psm
1602     // TODO: emit error event
1603     l2cap_service_t *service = l2cap_le_get_service(psm);
1604     if (service) {
1605         log_error("l2cap_le_register_service_internal: PSM %u already registered", psm);
1606         l2cap_emit_service_registered(connection, L2CAP_SERVICE_ALREADY_REGISTERED, psm);
1607         return;
1608     }
1609 
1610     // alloc structure
1611     // TODO: emit error event
1612     service = btstack_memory_l2cap_service_get();
1613     if (!service) {
1614         log_error("l2cap_register_service_internal: no memory for l2cap_service_t");
1615         l2cap_emit_service_registered(connection, BTSTACK_MEMORY_ALLOC_FAILED, psm);
1616         return;
1617     }
1618 
1619     // fill in
1620     service->psm = psm;
1621     service->mtu = mtu;
1622     service->mps = mps;
1623     service->packet_handler = packet_handler;
1624     service->required_security_level = security_level;
1625 
1626     // add to services list
1627     btstack_linked_list_add(&l2cap_le_services, (btstack_linked_item_t *) service);
1628 
1629     // done
1630     l2cap_emit_service_registered(connection, 0, psm);
1631 }
1632 
1633 void l2cap_le_unregister_service(uint16_t psm) {
1634 
1635     log_info("L2CAP_LE_UNREGISTER_SERVICE psm 0x%x", psm);
1636 
1637     l2cap_service_t *service = l2cap_le_get_service(psm);
1638     if (!service) return;
1639     btstack_linked_list_remove(&l2cap_le_services, (btstack_linked_item_t *) service);
1640     btstack_memory_l2cap_service_free(service);
1641 }
1642 #endif
1643 #endif
1644