xref: /btstack/src/l2cap.c (revision d9a7306a10f9a1b4dcae1f7fca484233f49c6707)
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
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30  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31  * SUCH DAMAGE.
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33  * Please inquire about commercial licensing options at
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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 static void null_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
70 
71 // used to cache l2cap rejects, echo, and informational requests
72 static l2cap_signaling_response_t signaling_responses[NR_PENDING_SIGNALING_RESPONSES];
73 static int signaling_responses_pending;
74 
75 static btstack_packet_callback_registration_t hci_event_callback_registration;
76 
77 static btstack_linked_list_t l2cap_channels;
78 static btstack_linked_list_t l2cap_services;
79 static btstack_linked_list_t l2cap_le_channels;
80 static btstack_linked_list_t l2cap_le_services;
81 static void (*packet_handler) (uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) = null_packet_handler;
82 
83 static btstack_packet_handler_t attribute_protocol_packet_handler;
84 static btstack_packet_handler_t security_protocol_packet_handler;
85 static btstack_packet_handler_t connectionless_channel_packet_handler;
86 static uint8_t require_security_level2_for_outgoing_sdp;
87 
88 // prototypes
89 static void l2cap_finialize_channel_close(l2cap_channel_t *channel);
90 static inline l2cap_service_t * l2cap_get_service(uint16_t psm);
91 static void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status);
92 static void l2cap_emit_channel_closed(l2cap_channel_t *channel);
93 static void l2cap_emit_connection_request(l2cap_channel_t *channel);
94 static int l2cap_channel_ready_for_open(l2cap_channel_t *channel);
95 static void l2cap_hci_event_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
96 static void l2cap_acl_handler(uint8_t packet_type, uint8_t *packet, uint16_t size );
97 
98 
99 void l2cap_init(void){
100     signaling_responses_pending = 0;
101 
102     l2cap_channels = NULL;
103     l2cap_services = NULL;
104     l2cap_le_services = NULL;
105     l2cap_le_channels = NULL;
106 
107     packet_handler = null_packet_handler;
108     attribute_protocol_packet_handler = NULL;
109     security_protocol_packet_handler = NULL;
110     connectionless_channel_packet_handler = NULL;
111 
112     require_security_level2_for_outgoing_sdp = 0;
113 
114     //
115     // register callback with HCI
116     //
117     hci_event_callback_registration.callback = &l2cap_hci_event_handler;
118     hci_add_event_handler(&hci_event_callback_registration);
119 
120     hci_register_acl_packet_handler(&l2cap_acl_handler);
121 
122     hci_connectable_control(0); // no services yet
123 }
124 
125 
126 /** Register L2CAP packet handlers */
127 static void null_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
128 }
129 void l2cap_register_packet_handler(void (*handler)(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size)){
130     packet_handler = handler;
131 }
132 
133 static void l2cap_dispatch_to_channel(l2cap_channel_t *channel, uint8_t type, uint8_t * data, uint16_t size){
134     (* (channel->packet_handler))(type, channel->local_cid, data, size);
135 }
136 
137 void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status) {
138     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",
139              status, bd_addr_to_str(channel->address), channel->handle, channel->psm,
140              channel->local_cid, channel->remote_cid, channel->local_mtu, channel->remote_mtu, channel->flush_timeout);
141     uint8_t event[23];
142     event[0] = L2CAP_EVENT_CHANNEL_OPENED;
143     event[1] = sizeof(event) - 2;
144     event[2] = status;
145     bt_flip_addr(&event[3], channel->address);
146     little_endian_store_16(event,  9, channel->handle);
147     little_endian_store_16(event, 11, channel->psm);
148     little_endian_store_16(event, 13, channel->local_cid);
149     little_endian_store_16(event, 15, channel->remote_cid);
150     little_endian_store_16(event, 17, channel->local_mtu);
151     little_endian_store_16(event, 19, channel->remote_mtu);
152     little_endian_store_16(event, 21, channel->flush_timeout);
153     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
154     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
155 }
156 
157 void l2cap_emit_channel_closed(l2cap_channel_t *channel) {
158     log_info("L2CAP_EVENT_CHANNEL_CLOSED local_cid 0x%x", channel->local_cid);
159     uint8_t event[4];
160     event[0] = L2CAP_EVENT_CHANNEL_CLOSED;
161     event[1] = sizeof(event) - 2;
162     little_endian_store_16(event, 2, channel->local_cid);
163     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
164     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
165 }
166 
167 void l2cap_emit_connection_request(l2cap_channel_t *channel) {
168     log_info("L2CAP_EVENT_INCOMING_CONNECTION addr %s handle 0x%x psm 0x%x local_cid 0x%x remote_cid 0x%x",
169              bd_addr_to_str(channel->address), channel->handle,  channel->psm, channel->local_cid, channel->remote_cid);
170     uint8_t event[16];
171     event[0] = L2CAP_EVENT_INCOMING_CONNECTION;
172     event[1] = sizeof(event) - 2;
173     bt_flip_addr(&event[2], channel->address);
174     little_endian_store_16(event,  8, channel->handle);
175     little_endian_store_16(event, 10, channel->psm);
176     little_endian_store_16(event, 12, channel->local_cid);
177     little_endian_store_16(event, 14, channel->remote_cid);
178     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
179     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
180 }
181 
182 static void l2cap_emit_connection_parameter_update_response(uint16_t handle, uint16_t result){
183     uint8_t event[6];
184     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_RESPONSE;
185     event[1] = 4;
186     little_endian_store_16(event, 2, handle);
187     little_endian_store_16(event, 4, result);
188     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
189     (*packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
190 }
191 
192 static l2cap_channel_t * l2cap_get_channel_for_local_cid(uint16_t local_cid){
193     btstack_linked_list_iterator_t it;
194     btstack_linked_list_iterator_init(&it, &l2cap_channels);
195     while (btstack_linked_list_iterator_has_next(&it)){
196         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
197         if ( channel->local_cid == local_cid) {
198             return channel;
199         }
200     }
201     return NULL;
202 }
203 
204 int  l2cap_can_send_packet_now(uint16_t local_cid){
205     l2cap_channel_t *channel = l2cap_get_channel_for_local_cid(local_cid);
206     if (!channel) return 0;
207     return hci_can_send_acl_packet_now(channel->handle);
208 }
209 
210 int  l2cap_can_send_prepared_packet_now(uint16_t local_cid){
211     l2cap_channel_t *channel = l2cap_get_channel_for_local_cid(local_cid);
212     if (!channel) return 0;
213     return hci_can_send_prepared_acl_packet_now(channel->handle);
214 }
215 
216 int  l2cap_can_send_fixed_channel_packet_now(uint16_t handle){
217     return hci_can_send_acl_packet_now(handle);
218 }
219 
220 uint16_t l2cap_get_remote_mtu_for_local_cid(uint16_t local_cid){
221     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
222     if (channel) {
223         return channel->remote_mtu;
224     }
225     return 0;
226 }
227 
228 static l2cap_channel_t * l2cap_channel_for_rtx_timer(btstack_timer_source_t * ts){
229     btstack_linked_list_iterator_t it;
230     btstack_linked_list_iterator_init(&it, &l2cap_channels);
231     while (btstack_linked_list_iterator_has_next(&it)){
232         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
233         if ( &channel->rtx == ts) {
234             return channel;
235         }
236     }
237     return NULL;
238 }
239 
240 static void l2cap_rtx_timeout(btstack_timer_source_t * ts){
241     l2cap_channel_t * channel = l2cap_channel_for_rtx_timer(ts);
242     if (!ts) return;
243 
244     log_info("l2cap_rtx_timeout for local cid 0x%02x", channel->local_cid);
245 
246     // "When terminating the channel, it is not necessary to send a L2CAP_DisconnectReq
247     //  and enter WAIT_DISCONNECT state. Channels can be transitioned directly to the CLOSED state."
248     // notify client
249     l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_RTX_TIMEOUT);
250 
251     // discard channel
252     // no need to stop timer here, it is removed from list during timer callback
253     btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
254     btstack_memory_l2cap_channel_free(channel);
255 }
256 
257 static void l2cap_stop_rtx(l2cap_channel_t * channel){
258     log_info("l2cap_stop_rtx for local cid 0x%02x", channel->local_cid);
259     btstack_run_loop_remove_timer(&channel->rtx);
260 }
261 
262 static void l2cap_start_rtx(l2cap_channel_t * channel){
263     l2cap_stop_rtx(channel);
264     log_info("l2cap_start_rtx for local cid 0x%02x", channel->local_cid);
265     btstack_run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
266     btstack_run_loop_set_timer(&channel->rtx, L2CAP_RTX_TIMEOUT_MS);
267     btstack_run_loop_add_timer(&channel->rtx);
268 }
269 
270 static void l2cap_start_ertx(l2cap_channel_t * channel){
271     log_info("l2cap_start_ertx for local cid 0x%02x", channel->local_cid);
272     l2cap_stop_rtx(channel);
273     btstack_run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
274     btstack_run_loop_set_timer(&channel->rtx, L2CAP_ERTX_TIMEOUT_MS);
275     btstack_run_loop_add_timer(&channel->rtx);
276 }
277 
278 void l2cap_require_security_level_2_for_outgoing_sdp(void){
279     require_security_level2_for_outgoing_sdp = 1;
280 }
281 
282 static int l2cap_security_level_0_allowed_for_PSM(uint16_t psm){
283     return (psm == PSM_SDP) && (!require_security_level2_for_outgoing_sdp);
284 }
285 
286 static int l2cap_send_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
287 
288     if (!hci_can_send_acl_packet_now(handle)){
289         log_info("l2cap_send_signaling_packet, cannot send");
290         return BTSTACK_ACL_BUFFERS_FULL;
291     }
292 
293     // log_info("l2cap_send_signaling_packet type %u", cmd);
294     hci_reserve_packet_buffer();
295     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
296     va_list argptr;
297     va_start(argptr, identifier);
298     uint16_t len = l2cap_create_signaling_classic(acl_buffer, handle, cmd, identifier, argptr);
299     va_end(argptr);
300     // log_info("l2cap_send_signaling_packet con %u!", handle);
301     return hci_send_acl_packet_buffer(len);
302 }
303 
304 #ifdef ENABLE_BLE
305 static int l2cap_send_le_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
306 
307     if (!hci_can_send_acl_packet_now(handle)){
308         log_info("l2cap_send_signaling_packet, cannot send");
309         return BTSTACK_ACL_BUFFERS_FULL;
310     }
311 
312     // log_info("l2cap_send_signaling_packet type %u", cmd);
313     hci_reserve_packet_buffer();
314     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
315     va_list argptr;
316     va_start(argptr, identifier);
317     uint16_t len = l2cap_create_signaling_le(acl_buffer, handle, cmd, identifier, argptr);
318     va_end(argptr);
319     // log_info("l2cap_send_signaling_packet con %u!", handle);
320     return hci_send_acl_packet_buffer(len);
321 }
322 #endif
323 
324 uint8_t *l2cap_get_outgoing_buffer(void){
325     return hci_get_outgoing_packet_buffer() + COMPLETE_L2CAP_HEADER; // 8 bytes
326 }
327 
328 int l2cap_reserve_packet_buffer(void){
329     return hci_reserve_packet_buffer();
330 }
331 
332 void l2cap_release_packet_buffer(void){
333     hci_release_packet_buffer();
334 }
335 
336 
337 int l2cap_send_prepared(uint16_t local_cid, uint16_t len){
338 
339     if (!hci_is_packet_buffer_reserved()){
340         log_error("l2cap_send_prepared called without reserving packet first");
341         return BTSTACK_ACL_BUFFERS_FULL;
342     }
343 
344     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
345     if (!channel) {
346         log_error("l2cap_send_prepared no channel for cid 0x%02x", local_cid);
347         return -1;   // TODO: define error
348     }
349 
350     if (!hci_can_send_prepared_acl_packet_now(channel->handle)){
351         log_info("l2cap_send_prepared cid 0x%02x, cannot send", local_cid);
352         return BTSTACK_ACL_BUFFERS_FULL;
353     }
354 
355     log_debug("l2cap_send_prepared cid 0x%02x, handle %u, 1 credit used", local_cid, channel->handle);
356 
357     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
358 
359     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
360 
361     // 0 - Connection handle : PB=pb : BC=00
362     little_endian_store_16(acl_buffer, 0, channel->handle | (pb << 12) | (0 << 14));
363     // 2 - ACL length
364     little_endian_store_16(acl_buffer, 2,  len + 4);
365     // 4 - L2CAP packet length
366     little_endian_store_16(acl_buffer, 4,  len + 0);
367     // 6 - L2CAP channel DEST
368     little_endian_store_16(acl_buffer, 6, channel->remote_cid);
369     // send
370     int err = hci_send_acl_packet_buffer(len+8);
371 
372     return err;
373 }
374 
375 int l2cap_send_prepared_connectionless(uint16_t handle, uint16_t cid, uint16_t len){
376 
377     if (!hci_is_packet_buffer_reserved()){
378         log_error("l2cap_send_prepared_connectionless called without reserving packet first");
379         return BTSTACK_ACL_BUFFERS_FULL;
380     }
381 
382     if (!hci_can_send_prepared_acl_packet_now(handle)){
383         log_info("l2cap_send_prepared_connectionless handle 0x%02x, cid 0x%02x, cannot send", handle, cid);
384         return BTSTACK_ACL_BUFFERS_FULL;
385     }
386 
387     log_debug("l2cap_send_prepared_connectionless handle %u, cid 0x%02x", handle, cid);
388 
389     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
390 
391     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
392 
393     // 0 - Connection handle : PB=pb : BC=00
394     little_endian_store_16(acl_buffer, 0, handle | (pb << 12) | (0 << 14));
395     // 2 - ACL length
396     little_endian_store_16(acl_buffer, 2,  len + 4);
397     // 4 - L2CAP packet length
398     little_endian_store_16(acl_buffer, 4,  len + 0);
399     // 6 - L2CAP channel DEST
400     little_endian_store_16(acl_buffer, 6, cid);
401     // send
402     int err = hci_send_acl_packet_buffer(len+8);
403 
404     return err;
405 }
406 
407 int l2cap_send(uint16_t local_cid, uint8_t *data, uint16_t len){
408 
409     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
410     if (!channel) {
411         log_error("l2cap_send no channel for cid 0x%02x", local_cid);
412         return -1;   // TODO: define error
413     }
414 
415     if (len > channel->remote_mtu){
416         log_error("l2cap_send cid 0x%02x, data length exceeds remote MTU.", local_cid);
417         return L2CAP_DATA_LEN_EXCEEDS_REMOTE_MTU;
418     }
419 
420     if (!hci_can_send_acl_packet_now(channel->handle)){
421         log_info("l2cap_send cid 0x%02x, cannot send", local_cid);
422         return BTSTACK_ACL_BUFFERS_FULL;
423     }
424 
425     hci_reserve_packet_buffer();
426     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
427 
428     memcpy(&acl_buffer[8], data, len);
429 
430     return l2cap_send_prepared(local_cid, len);
431 }
432 
433 int l2cap_send_connectionless(uint16_t handle, uint16_t cid, uint8_t *data, uint16_t len){
434 
435     if (!hci_can_send_acl_packet_now(handle)){
436         log_info("l2cap_send cid 0x%02x, cannot send", cid);
437         return BTSTACK_ACL_BUFFERS_FULL;
438     }
439 
440     hci_reserve_packet_buffer();
441     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
442 
443     memcpy(&acl_buffer[8], data, len);
444 
445     return l2cap_send_prepared_connectionless(handle, cid, len);
446 }
447 
448 int l2cap_send_echo_request(uint16_t handle, uint8_t *data, uint16_t len){
449     return l2cap_send_signaling_packet(handle, ECHO_REQUEST, 0x77, len, data);
450 }
451 
452 static inline void channelStateVarSetFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
453     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var | flag);
454 }
455 
456 static inline void channelStateVarClearFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
457     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var & ~flag);
458 }
459 
460 
461 
462 // MARK: L2CAP_RUN
463 // process outstanding signaling tasks
464 static void l2cap_run(void){
465 
466     // log_info("l2cap_run: entered");
467 
468     // check pending signaling responses
469     while (signaling_responses_pending){
470 
471         hci_con_handle_t handle = signaling_responses[0].handle;
472 
473         if (!hci_can_send_acl_packet_now(handle)) break;
474 
475         uint8_t  sig_id = signaling_responses[0].sig_id;
476         uint16_t infoType = signaling_responses[0].data;    // INFORMATION_REQUEST
477         uint16_t result   = signaling_responses[0].data;    // CONNECTION_REQUEST, COMMAND_REJECT
478         uint8_t  response_code = signaling_responses[0].code;
479 
480         // remove first item before sending (to avoid sending response mutliple times)
481         signaling_responses_pending--;
482         int i;
483         for (i=0; i < signaling_responses_pending; i++){
484             memcpy(&signaling_responses[i], &signaling_responses[i+1], sizeof(l2cap_signaling_response_t));
485         }
486 
487         switch (response_code){
488             case CONNECTION_REQUEST:
489                 l2cap_send_signaling_packet(handle, CONNECTION_RESPONSE, sig_id, 0, 0, result, 0);
490                 // also disconnect if result is 0x0003 - security blocked
491                 if (result == 0x0003){
492                     hci_disconnect_security_block(handle);
493                 }
494                 break;
495             case ECHO_REQUEST:
496                 l2cap_send_signaling_packet(handle, ECHO_RESPONSE, sig_id, 0, NULL);
497                 break;
498             case INFORMATION_REQUEST:
499                 switch (infoType){
500                     case 1: { // Connectionless MTU
501                         uint16_t connectionless_mtu = hci_max_acl_data_packet_length();
502                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(connectionless_mtu), &connectionless_mtu);
503                         break;
504                     }
505                     case 2: { // Extended Features Supported
506                         // extended features request supported, features: fixed channels, unicast connectionless data reception
507                         uint32_t features = 0x280;
508                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(features), &features);
509                         break;
510                     }
511                     case 3: { // Fixed Channels Supported
512                         uint8_t map[8];
513                         memset(map, 0, 8);
514                         map[0] = 0x01;  // L2CAP Signaling Channel (0x01) + Connectionless reception (0x02)
515                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(map), &map);
516                         break;
517                     }
518                     default:
519                         // all other types are not supported
520                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 1, 0, NULL);
521                         break;
522                 }
523                 break;
524             case COMMAND_REJECT:
525                 l2cap_send_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
526 #ifdef ENABLE_BLE
527             case COMMAND_REJECT_LE:
528                 l2cap_send_le_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
529                 break;
530 #endif
531             default:
532                 // should not happen
533                 break;
534         }
535     }
536 
537     uint8_t  config_options[4];
538     btstack_linked_list_iterator_t it;
539     btstack_linked_list_iterator_init(&it, &l2cap_channels);
540     while (btstack_linked_list_iterator_has_next(&it)){
541 
542         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
543         // log_info("l2cap_run: channel %p, state %u, var 0x%02x", channel, channel->state, channel->state_var);
544         switch (channel->state){
545 
546             case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
547             case L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT:
548                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
549                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND) {
550                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND);
551                     l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 1, 0);
552                 }
553                 break;
554 
555             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
556                 if (!hci_can_send_command_packet_now()) break;
557                 // send connection request - set state first
558                 channel->state = L2CAP_STATE_WAIT_CONNECTION_COMPLETE;
559                 // BD_ADDR, Packet_Type, Page_Scan_Repetition_Mode, Reserved, Clock_Offset, Allow_Role_Switch
560                 hci_send_cmd(&hci_create_connection, channel->address, hci_usable_acl_packet_types(), 0, 0, 0, 1);
561                 break;
562 
563             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE:
564                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
565                 channel->state = L2CAP_STATE_INVALID;
566                 l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, channel->reason, 0);
567                 // discard channel - l2cap_finialize_channel_close without sending l2cap close event
568                 l2cap_stop_rtx(channel);
569                 btstack_linked_list_iterator_remove(&it);
570                 btstack_memory_l2cap_channel_free(channel);
571                 break;
572 
573             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT:
574                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
575                 channel->state = L2CAP_STATE_CONFIG;
576                 channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
577                 l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 0, 0);
578                 break;
579 
580             case L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST:
581                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
582                 // success, start l2cap handshake
583                 channel->local_sig_id = l2cap_next_sig_id();
584                 channel->state = L2CAP_STATE_WAIT_CONNECT_RSP;
585                 l2cap_send_signaling_packet( channel->handle, CONNECTION_REQUEST, channel->local_sig_id, channel->psm, channel->local_cid);
586                 l2cap_start_rtx(channel);
587                 break;
588 
589             case L2CAP_STATE_CONFIG:
590                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
591                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP){
592                     uint16_t flags = 0;
593                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
594                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT) {
595                         flags = 1;
596                     } else {
597                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP);
598                     }
599                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID){
600                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, L2CAP_CONF_RESULT_UNKNOWN_OPTIONS, 0, NULL);
601                     } else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU){
602                         config_options[0] = 1; // MTU
603                         config_options[1] = 2; // len param
604                         little_endian_store_16( (uint8_t*)&config_options, 2, channel->remote_mtu);
605                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 4, &config_options);
606                         channelStateVarClearFlag(channel,L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
607                     } else {
608                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 0, NULL);
609                     }
610                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
611                 }
612                 else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ){
613                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
614                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_REQ);
615                     channel->local_sig_id = l2cap_next_sig_id();
616                     config_options[0] = 1; // MTU
617                     config_options[1] = 2; // len param
618                     little_endian_store_16( (uint8_t*)&config_options, 2, channel->local_mtu);
619                     l2cap_send_signaling_packet(channel->handle, CONFIGURE_REQUEST, channel->local_sig_id, channel->remote_cid, 0, 4, &config_options);
620                     l2cap_start_rtx(channel);
621                 }
622                 if (l2cap_channel_ready_for_open(channel)){
623                     channel->state = L2CAP_STATE_OPEN;
624                     l2cap_emit_channel_opened(channel, 0);  // success
625                 }
626                 break;
627 
628             case L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE:
629                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
630                 channel->state = L2CAP_STATE_INVALID;
631                 l2cap_send_signaling_packet( channel->handle, DISCONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid);
632                 // 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 :)
633                 l2cap_finialize_channel_close(channel);  // -- remove from list
634                 break;
635 
636             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
637                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
638                 channel->local_sig_id = l2cap_next_sig_id();
639                 channel->state = L2CAP_STATE_WAIT_DISCONNECT;
640                 l2cap_send_signaling_packet( channel->handle, DISCONNECTION_REQUEST, channel->local_sig_id, channel->remote_cid, channel->local_cid);
641                 break;
642             default:
643                 break;
644         }
645     }
646 
647 #ifdef ENABLE_BLE
648     // send l2cap con paramter update if necessary
649     hci_connections_get_iterator(&it);
650     while(btstack_linked_list_iterator_has_next(&it)){
651         hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it);
652         if (connection->address_type != BD_ADDR_TYPE_LE_PUBLIC && connection->address_type != BD_ADDR_TYPE_LE_RANDOM) continue;
653         if (!hci_can_send_acl_packet_now(connection->con_handle)) continue;
654         switch (connection->le_con_parameter_update_state){
655             case CON_PARAMETER_UPDATE_SEND_REQUEST:
656                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_NONE;
657                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_REQUEST, connection->le_con_param_update_identifier,
658                                                connection->le_conn_interval_min, connection->le_conn_interval_max, connection->le_conn_latency, connection->le_supervision_timeout);
659                 break;
660             case CON_PARAMETER_UPDATE_SEND_RESPONSE:
661                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_CHANGE_HCI_CON_PARAMETERS;
662                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_RESPONSE, connection->le_con_param_update_identifier, 0);
663                 break;
664             case CON_PARAMETER_UPDATE_DENY:
665                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_NONE;
666                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_RESPONSE, connection->le_con_param_update_identifier, 1);
667                 break;
668             default:
669                 break;
670         }
671     }
672 #endif
673 
674     // log_info("l2cap_run: exit");
675 }
676 
677 uint16_t l2cap_max_mtu(void){
678     return HCI_ACL_PAYLOAD_SIZE - L2CAP_HEADER_SIZE;
679 }
680 
681 uint16_t l2cap_max_le_mtu(void){
682     return l2cap_max_mtu();
683 }
684 
685 static void l2cap_handle_connection_complete(uint16_t handle, l2cap_channel_t * channel){
686     if (channel->state == L2CAP_STATE_WAIT_CONNECTION_COMPLETE || channel->state == L2CAP_STATE_WILL_SEND_CREATE_CONNECTION) {
687         log_info("l2cap_handle_connection_complete expected state");
688         // success, start l2cap handshake
689         channel->handle = handle;
690         // check remote SSP feature first
691         channel->state = L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES;
692     }
693 }
694 
695 static void l2cap_handle_remote_supported_features_received(l2cap_channel_t * channel){
696     if (channel->state != L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES) return;
697 
698     // we have been waiting for remote supported features, if both support SSP,
699     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));
700     if (hci_ssp_supported_on_both_sides(channel->handle) && !l2cap_security_level_0_allowed_for_PSM(channel->psm)){
701         // request security level 2
702         channel->state = L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE;
703         gap_request_security_level(channel->handle, LEVEL_2);
704         return;
705     }
706     // fine, go ahead
707     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
708 }
709 
710 /**
711  * @brief Creates L2CAP channel to the PSM of a remote device with baseband address. A new baseband connection will be initiated if necessary.
712  * @param packet_handler
713  * @param address
714  * @param psm
715  * @param mtu
716  * @param local_cid
717  */
718 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){
719     log_info("L2CAP_CREATE_CHANNEL addr %s psm 0x%x mtu %u", bd_addr_to_str(address), psm, mtu);
720 
721     // alloc structure
722     l2cap_channel_t * chan = btstack_memory_l2cap_channel_get();
723     if (!chan) {
724         return BTSTACK_MEMORY_ALLOC_FAILED;
725     }
726 
727      // Init memory (make valgrind happy)
728     memset(chan, 0, sizeof(l2cap_channel_t));
729     // limit local mtu to max acl packet length - l2cap header
730     if (mtu > l2cap_max_mtu()) {
731         mtu = l2cap_max_mtu();
732     }
733 
734     // fill in
735     BD_ADDR_COPY(chan->address, address);
736     chan->psm = psm;
737     chan->handle = 0;
738     chan->packet_handler = channel_packet_handler;
739     chan->remote_mtu = L2CAP_MINIMAL_MTU;
740     chan->local_mtu = mtu;
741     chan->local_cid = l2cap_next_local_cid();
742 
743     // set initial state
744     chan->state = L2CAP_STATE_WILL_SEND_CREATE_CONNECTION;
745     chan->state_var = L2CAP_CHANNEL_STATE_VAR_NONE;
746     chan->remote_sig_id = L2CAP_SIG_ID_INVALID;
747     chan->local_sig_id = L2CAP_SIG_ID_INVALID;
748     chan->required_security_level = LEVEL_0;
749 
750     // add to connections list
751     btstack_linked_list_add(&l2cap_channels, (btstack_linked_item_t *) chan);
752 
753     // store local_cid
754     if (out_local_cid){
755        *out_local_cid = chan->local_cid;
756     }
757 
758     // check if hci connection is already usable
759     hci_connection_t * conn = hci_connection_for_bd_addr_and_type(address, BD_ADDR_TYPE_CLASSIC);
760     if (conn){
761         log_info("l2cap_create_channel, hci connection already exists");
762         l2cap_handle_connection_complete(conn->con_handle, chan);
763         // check if remote supported fearures are already received
764         if (conn->bonding_flags & BONDING_RECEIVED_REMOTE_FEATURES) {
765             l2cap_handle_remote_supported_features_received(chan);
766         }
767     }
768 
769     l2cap_run();
770 
771     return 0;
772 }
773 
774 void
775 l2cap_disconnect(uint16_t local_cid, uint8_t reason){
776     log_info("L2CAP_DISCONNECT local_cid 0x%x reason 0x%x", local_cid, reason);
777     // find channel for local_cid
778     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
779     if (channel) {
780         channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST;
781     }
782     // process
783     l2cap_run();
784 }
785 
786 static void l2cap_handle_connection_failed_for_addr(bd_addr_t address, uint8_t status){
787     btstack_linked_list_iterator_t it;
788     btstack_linked_list_iterator_init(&it, &l2cap_channels);
789     while (btstack_linked_list_iterator_has_next(&it)){
790         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
791         if ( BD_ADDR_CMP( channel->address, address) != 0) continue;
792         // channel for this address found
793         switch (channel->state){
794             case L2CAP_STATE_WAIT_CONNECTION_COMPLETE:
795             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
796                 // failure, forward error code
797                 l2cap_emit_channel_opened(channel, status);
798                 // discard channel
799                 l2cap_stop_rtx(channel);
800                 btstack_linked_list_iterator_remove(&it);
801                 btstack_memory_l2cap_channel_free(channel);
802                 break;
803             default:
804                 break;
805         }
806     }
807 }
808 
809 static void l2cap_handle_connection_success_for_addr(bd_addr_t address, hci_con_handle_t handle){
810     btstack_linked_list_iterator_t it;
811     btstack_linked_list_iterator_init(&it, &l2cap_channels);
812     while (btstack_linked_list_iterator_has_next(&it)){
813         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
814         if ( ! BD_ADDR_CMP( channel->address, address) ){
815             l2cap_handle_connection_complete(handle, channel);
816         }
817     }
818     // process
819     l2cap_run();
820 }
821 
822 static void l2cap_hci_event_handler(uint8_t packet_type, uint16_t cid, uint8_t *packet, uint16_t size){
823 
824     bd_addr_t address;
825     hci_con_handle_t handle;
826     btstack_linked_list_iterator_t it;
827     int hci_con_used;
828 
829     switch(packet[0]){
830 
831         // handle connection complete events
832         case HCI_EVENT_CONNECTION_COMPLETE:
833             bt_flip_addr(address, &packet[5]);
834             if (packet[2] == 0){
835                 handle = little_endian_read_16(packet, 3);
836                 l2cap_handle_connection_success_for_addr(address, handle);
837             } else {
838                 l2cap_handle_connection_failed_for_addr(address, packet[2]);
839             }
840             break;
841 
842         // handle successful create connection cancel command
843         case HCI_EVENT_COMMAND_COMPLETE:
844             if ( COMMAND_COMPLETE_EVENT(packet, hci_create_connection_cancel) ) {
845                 if (packet[5] == 0){
846                     bt_flip_addr(address, &packet[6]);
847                     // CONNECTION TERMINATED BY LOCAL HOST (0X16)
848                     l2cap_handle_connection_failed_for_addr(address, 0x16);
849                 }
850             }
851             l2cap_run();    // try sending signaling packets first
852             break;
853 
854         case HCI_EVENT_COMMAND_STATUS:
855             l2cap_run();    // try sending signaling packets first
856             break;
857 
858         // handle disconnection complete events
859         case HCI_EVENT_DISCONNECTION_COMPLETE:
860             // send l2cap disconnect events for all channels on this handle and free them
861             handle = little_endian_read_16(packet, 3);
862             btstack_linked_list_iterator_init(&it, &l2cap_channels);
863             while (btstack_linked_list_iterator_has_next(&it)){
864                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
865                 if (channel->handle != handle) continue;
866                 l2cap_emit_channel_closed(channel);
867                 l2cap_stop_rtx(channel);
868                 btstack_linked_list_iterator_remove(&it);
869                 btstack_memory_l2cap_channel_free(channel);
870             }
871             break;
872 
873         case HCI_EVENT_NUMBER_OF_COMPLETED_PACKETS:
874             l2cap_run();    // try sending signaling packets first
875             break;
876 
877         // HCI Connection Timeouts
878         case L2CAP_EVENT_TIMEOUT_CHECK:
879             handle = little_endian_read_16(packet, 2);
880             if (gap_get_connection_type(handle) != GAP_CONNECTION_ACL) break;
881             if (hci_authentication_active_for_handle(handle)) break;
882             hci_con_used = 0;
883             btstack_linked_list_iterator_init(&it, &l2cap_channels);
884             while (btstack_linked_list_iterator_has_next(&it)){
885                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
886                 if (channel->handle != handle) continue;
887                 hci_con_used = 1;
888                 break;
889             }
890             if (hci_con_used) break;
891             if (!hci_can_send_command_packet_now()) break;
892             hci_send_cmd(&hci_disconnect, handle, 0x13); // remote closed connection
893             break;
894 
895         case DAEMON_EVENT_HCI_PACKET_SENT:
896             l2cap_run();    // try sending signaling packets first
897 
898             btstack_linked_list_iterator_init(&it, &l2cap_channels);
899             while (btstack_linked_list_iterator_has_next(&it)){
900                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
901                 if (!channel->packet_handler) continue;
902                 (* (channel->packet_handler))(HCI_EVENT_PACKET, channel->local_cid, packet, size);
903             }
904             break;
905 
906         case HCI_EVENT_READ_REMOTE_SUPPORTED_FEATURES_COMPLETE:
907             handle = little_endian_read_16(packet, 3);
908             btstack_linked_list_iterator_init(&it, &l2cap_channels);
909             while (btstack_linked_list_iterator_has_next(&it)){
910                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
911                 if (channel->handle != handle) continue;
912                 l2cap_handle_remote_supported_features_received(channel);
913                 break;
914             }
915             break;
916 
917         case GAP_EVENT_SECURITY_LEVEL:
918             handle = little_endian_read_16(packet, 2);
919             log_info("l2cap - security level update");
920             btstack_linked_list_iterator_init(&it, &l2cap_channels);
921             while (btstack_linked_list_iterator_has_next(&it)){
922                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
923                 if (channel->handle != handle) continue;
924 
925                 log_info("l2cap - state %u", channel->state);
926 
927                 gap_security_level_t actual_level = (gap_security_level_t) packet[4];
928                 gap_security_level_t required_level = channel->required_security_level;
929 
930                 switch (channel->state){
931                     case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
932                         if (actual_level >= required_level){
933                             channel->state = L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT;
934                             l2cap_emit_connection_request(channel);
935                         } else {
936                             channel->reason = 0x0003; // security block
937                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
938                         }
939                         break;
940 
941                     case L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE:
942                         if (actual_level >= required_level){
943                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
944                         } else {
945                             // disconnnect, authentication not good enough
946                             hci_disconnect_security_block(handle);
947                         }
948                         break;
949 
950                     default:
951                         break;
952                 }
953             }
954             break;
955 
956         default:
957             break;
958     }
959 
960     l2cap_run();
961 }
962 
963 static void l2cap_handle_disconnect_request(l2cap_channel_t *channel, uint16_t identifier){
964     channel->remote_sig_id = identifier;
965     channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE;
966     l2cap_run();
967 }
968 
969 static void l2cap_register_signaling_response(hci_con_handle_t handle, uint8_t code, uint8_t sig_id, uint16_t data){
970     // Vol 3, Part A, 4.3: "The DCID and SCID fields shall be ignored when the result field indi- cates the connection was refused."
971     if (signaling_responses_pending < NR_PENDING_SIGNALING_RESPONSES) {
972         signaling_responses[signaling_responses_pending].handle = handle;
973         signaling_responses[signaling_responses_pending].code = code;
974         signaling_responses[signaling_responses_pending].sig_id = sig_id;
975         signaling_responses[signaling_responses_pending].data = data;
976         signaling_responses_pending++;
977         l2cap_run();
978     }
979 }
980 
981 static void l2cap_handle_connection_request(hci_con_handle_t handle, uint8_t sig_id, uint16_t psm, uint16_t source_cid){
982 
983     // log_info("l2cap_handle_connection_request for handle %u, psm %u cid 0x%02x", handle, psm, source_cid);
984     l2cap_service_t *service = l2cap_get_service(psm);
985     if (!service) {
986         // 0x0002 PSM not supported
987         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0002);
988         return;
989     }
990 
991     hci_connection_t * hci_connection = hci_connection_for_handle( handle );
992     if (!hci_connection) {
993         //
994         log_error("no hci_connection for handle %u", handle);
995         return;
996     }
997 
998     // alloc structure
999     // log_info("l2cap_handle_connection_request register channel");
1000     l2cap_channel_t * channel = btstack_memory_l2cap_channel_get();
1001     if (!channel){
1002         // 0x0004 No resources available
1003         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0004);
1004         return;
1005     }
1006     // Init memory (make valgrind happy)
1007     memset(channel, 0, sizeof(l2cap_channel_t));
1008     // fill in
1009     BD_ADDR_COPY(channel->address, hci_connection->address);
1010     channel->psm = psm;
1011     channel->handle = handle;
1012     channel->packet_handler = service->packet_handler;
1013     channel->local_cid  = l2cap_next_local_cid();
1014     channel->remote_cid = source_cid;
1015     channel->local_mtu  = service->mtu;
1016     channel->remote_mtu = L2CAP_DEFAULT_MTU;
1017     channel->remote_sig_id = sig_id;
1018     channel->required_security_level = service->required_security_level;
1019 
1020     // limit local mtu to max acl packet length - l2cap header
1021     if (channel->local_mtu > l2cap_max_mtu()) {
1022         channel->local_mtu = l2cap_max_mtu();
1023     }
1024 
1025     // set initial state
1026     channel->state =     L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE;
1027     channel->state_var = L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND;
1028 
1029     // add to connections list
1030     btstack_linked_list_add(&l2cap_channels, (btstack_linked_item_t *) channel);
1031 
1032     // assert security requirements
1033     gap_request_security_level(handle, channel->required_security_level);
1034 }
1035 
1036 void l2cap_accept_connection(uint16_t local_cid){
1037     log_info("L2CAP_ACCEPT_CONNECTION local_cid 0x%x", local_cid);
1038     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
1039     if (!channel) {
1040         log_error("l2cap_accept_connection called but local_cid 0x%x not found", local_cid);
1041         return;
1042     }
1043 
1044     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT;
1045 
1046     // process
1047     l2cap_run();
1048 }
1049 
1050 void l2cap_decline_connection(uint16_t local_cid, uint8_t reason){
1051     log_info("L2CAP_DECLINE_CONNECTION local_cid 0x%x, reason %x", local_cid, reason);
1052     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid( local_cid);
1053     if (!channel) {
1054         log_error( "l2cap_decline_connection called but local_cid 0x%x not found", local_cid);
1055         return;
1056     }
1057     channel->state  = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
1058     channel->reason = reason;
1059     l2cap_run();
1060 }
1061 
1062 static void l2cap_signaling_handle_configure_request(l2cap_channel_t *channel, uint8_t *command){
1063 
1064     channel->remote_sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1065 
1066     uint16_t flags = little_endian_read_16(command, 6);
1067     if (flags & 1) {
1068         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
1069     }
1070 
1071     // accept the other's configuration options
1072     uint16_t end_pos = 4 + little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1073     uint16_t pos     = 8;
1074     while (pos < end_pos){
1075         uint8_t option_hint = command[pos] >> 7;
1076         uint8_t option_type = command[pos] & 0x7f;
1077         log_info("l2cap cid %u, hint %u, type %u", channel->local_cid, option_hint, option_type);
1078         pos++;
1079         uint8_t length = command[pos++];
1080         // MTU { type(8): 1, len(8):2, MTU(16) }
1081         if (option_type == 1 && length == 2){
1082             channel->remote_mtu = little_endian_read_16(command, pos);
1083             // log_info("l2cap cid 0x%02x, remote mtu %u", channel->local_cid, channel->remote_mtu);
1084             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
1085         }
1086         // Flush timeout { type(8):2, len(8): 2, Flush Timeout(16)}
1087         if (option_type == 2 && length == 2){
1088             channel->flush_timeout = little_endian_read_16(command, pos);
1089         }
1090         // check for unknown options
1091         if (option_hint == 0 && (option_type == 0 || option_type >= 0x07)){
1092             log_info("l2cap cid %u, unknown options", channel->local_cid);
1093             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID);
1094         }
1095         pos += length;
1096     }
1097 }
1098 
1099 static int l2cap_channel_ready_for_open(l2cap_channel_t *channel){
1100     // log_info("l2cap_channel_ready_for_open 0x%02x", channel->state_var);
1101     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP) == 0) return 0;
1102     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP) == 0) return 0;
1103     // addition check that fixes re-entrance issue causing l2cap event channel opened twice
1104     if (channel->state == L2CAP_STATE_OPEN) return 0;
1105     return 1;
1106 }
1107 
1108 
1109 static void l2cap_signaling_handler_channel(l2cap_channel_t *channel, uint8_t *command){
1110 
1111     uint8_t  code       = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1112     uint8_t  identifier = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1113     uint16_t result = 0;
1114 
1115     log_info("L2CAP signaling handler code %u, state %u", code, channel->state);
1116 
1117     // handle DISCONNECT REQUESTS seperately
1118     if (code == DISCONNECTION_REQUEST){
1119         switch (channel->state){
1120             case L2CAP_STATE_CONFIG:
1121             case L2CAP_STATE_OPEN:
1122             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
1123             case L2CAP_STATE_WAIT_DISCONNECT:
1124                 l2cap_handle_disconnect_request(channel, identifier);
1125                 break;
1126 
1127             default:
1128                 // ignore in other states
1129                 break;
1130         }
1131         return;
1132     }
1133 
1134     // @STATEMACHINE(l2cap)
1135     switch (channel->state) {
1136 
1137         case L2CAP_STATE_WAIT_CONNECT_RSP:
1138             switch (code){
1139                 case CONNECTION_RESPONSE:
1140                     l2cap_stop_rtx(channel);
1141                     result = little_endian_read_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1142                     switch (result) {
1143                         case 0:
1144                             // successful connection
1145                             channel->remote_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1146                             channel->state = L2CAP_STATE_CONFIG;
1147                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1148                             break;
1149                         case 1:
1150                             // connection pending. get some coffee, but start the ERTX
1151                             l2cap_start_ertx(channel);
1152                             break;
1153                         default:
1154                             // channel closed
1155                             channel->state = L2CAP_STATE_CLOSED;
1156                             // map l2cap connection response result to BTstack status enumeration
1157                             l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result);
1158 
1159                             // drop link key if security block
1160                             if (L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result == L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_SECURITY){
1161                                 hci_drop_link_key_for_bd_addr(channel->address);
1162                             }
1163 
1164                             // discard channel
1165                             btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
1166                             btstack_memory_l2cap_channel_free(channel);
1167                             break;
1168                     }
1169                     break;
1170 
1171                 default:
1172                     //@TODO: implement other signaling packets
1173                     break;
1174             }
1175             break;
1176 
1177         case L2CAP_STATE_CONFIG:
1178             result = little_endian_read_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1179             switch (code) {
1180                 case CONFIGURE_REQUEST:
1181                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
1182                     l2cap_signaling_handle_configure_request(channel, command);
1183                     if (!(channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT)){
1184                         // only done if continuation not set
1185                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_REQ);
1186                     }
1187                     break;
1188                 case CONFIGURE_RESPONSE:
1189                     l2cap_stop_rtx(channel);
1190                     switch (result){
1191                         case 0: // success
1192                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP);
1193                             break;
1194                         case 4: // pending
1195                             l2cap_start_ertx(channel);
1196                             break;
1197                         default:
1198                             // retry on negative result
1199                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1200                             break;
1201                     }
1202                     break;
1203                 default:
1204                     break;
1205             }
1206             if (l2cap_channel_ready_for_open(channel)){
1207                 // for open:
1208                 channel->state = L2CAP_STATE_OPEN;
1209                 l2cap_emit_channel_opened(channel, 0);
1210             }
1211             break;
1212 
1213         case L2CAP_STATE_WAIT_DISCONNECT:
1214             switch (code) {
1215                 case DISCONNECTION_RESPONSE:
1216                     l2cap_finialize_channel_close(channel);
1217                     break;
1218                 default:
1219                     //@TODO: implement other signaling packets
1220                     break;
1221             }
1222             break;
1223 
1224         case L2CAP_STATE_CLOSED:
1225             // @TODO handle incoming requests
1226             break;
1227 
1228         case L2CAP_STATE_OPEN:
1229             //@TODO: implement other signaling packets, e.g. re-configure
1230             break;
1231         default:
1232             break;
1233     }
1234     // log_info("new state %u", channel->state);
1235 }
1236 
1237 
1238 static void l2cap_signaling_handler_dispatch( hci_con_handle_t handle, uint8_t * command){
1239 
1240     // get code, signalind identifier and command len
1241     uint8_t code   = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1242     uint8_t sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1243 
1244     // not for a particular channel, and not CONNECTION_REQUEST, ECHO_[REQUEST|RESPONSE], INFORMATION_REQUEST
1245     if (code < 1 || code == ECHO_RESPONSE || code > INFORMATION_REQUEST){
1246         l2cap_register_signaling_response(handle, COMMAND_REJECT, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1247         return;
1248     }
1249 
1250     // general commands without an assigned channel
1251     switch(code) {
1252 
1253         case CONNECTION_REQUEST: {
1254             uint16_t psm =        little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1255             uint16_t source_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+2);
1256             l2cap_handle_connection_request(handle, sig_id, psm, source_cid);
1257             return;
1258         }
1259 
1260         case ECHO_REQUEST:
1261             l2cap_register_signaling_response(handle, code, sig_id, 0);
1262             return;
1263 
1264         case INFORMATION_REQUEST: {
1265             uint16_t infoType = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1266             l2cap_register_signaling_response(handle, code, sig_id, infoType);
1267             return;
1268         }
1269 
1270         default:
1271             break;
1272     }
1273 
1274 
1275     // Get potential destination CID
1276     uint16_t dest_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1277 
1278     // Find channel for this sig_id and connection handle
1279     btstack_linked_list_iterator_t it;
1280     btstack_linked_list_iterator_init(&it, &l2cap_channels);
1281     while (btstack_linked_list_iterator_has_next(&it)){
1282         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
1283         if (channel->handle != handle) continue;
1284         if (code & 1) {
1285             // match odd commands (responses) by previous signaling identifier
1286             if (channel->local_sig_id == sig_id) {
1287                 l2cap_signaling_handler_channel(channel, command);
1288                 break;
1289             }
1290         } else {
1291             // match even commands (requests) by local channel id
1292             if (channel->local_cid == dest_cid) {
1293                 l2cap_signaling_handler_channel(channel, command);
1294                 break;
1295             }
1296         }
1297     }
1298 }
1299 
1300 static void l2cap_acl_handler(uint8_t packet_type, uint8_t *packet, uint16_t size ){
1301 
1302     // Get Channel ID
1303     uint16_t channel_id = READ_L2CAP_CHANNEL_ID(packet);
1304     hci_con_handle_t handle = READ_ACL_CONNECTION_HANDLE(packet);
1305 
1306     switch (channel_id) {
1307 
1308         case L2CAP_CID_SIGNALING: {
1309 
1310             uint16_t command_offset = 8;
1311             while (command_offset < size) {
1312 
1313                 // handle signaling commands
1314                 l2cap_signaling_handler_dispatch(handle, &packet[command_offset]);
1315 
1316                 // increment command_offset
1317                 command_offset += L2CAP_SIGNALING_COMMAND_DATA_OFFSET + little_endian_read_16(packet, command_offset + L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1318             }
1319             break;
1320         }
1321 
1322         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
1323             if (attribute_protocol_packet_handler) {
1324                 (*attribute_protocol_packet_handler)(ATT_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1325             }
1326             break;
1327 
1328         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
1329             if (security_protocol_packet_handler) {
1330                 (*security_protocol_packet_handler)(SM_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1331             }
1332             break;
1333 
1334         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
1335             if (connectionless_channel_packet_handler) {
1336                 (*connectionless_channel_packet_handler)(UCD_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1337             }
1338             break;
1339 
1340         case L2CAP_CID_SIGNALING_LE: {
1341             switch (packet[8]){
1342                 case CONNECTION_PARAMETER_UPDATE_RESPONSE: {
1343                     uint16_t result = little_endian_read_16(packet, 12);
1344                     l2cap_emit_connection_parameter_update_response(handle, result);
1345                     break;
1346                 }
1347                 case CONNECTION_PARAMETER_UPDATE_REQUEST: {
1348                     uint8_t event[10];
1349                     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_REQUEST;
1350                     event[1] = 8;
1351                     memcpy(&event[2], &packet[12], 8);
1352 
1353                     hci_connection_t * connection = hci_connection_for_handle(handle);
1354                     if (connection){
1355                         if (connection->role != HCI_ROLE_MASTER){
1356                             // reject command without notifying upper layer when not in master role
1357                             uint8_t sig_id = packet[COMPLETE_L2CAP_HEADER + 1];
1358                             l2cap_register_signaling_response(handle, COMMAND_REJECT_LE, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1359                             break;
1360                         }
1361                         int update_parameter = 1;
1362                         le_connection_parameter_range_t existing_range;
1363                         gap_le_get_connection_parameter_range(existing_range);
1364                         uint16_t le_conn_interval_min = little_endian_read_16(packet,12);
1365                         uint16_t le_conn_interval_max = little_endian_read_16(packet,14);
1366                         uint16_t le_conn_latency = little_endian_read_16(packet,16);
1367                         uint16_t le_supervision_timeout = little_endian_read_16(packet,18);
1368 
1369                         if (le_conn_interval_min < existing_range.le_conn_interval_min) update_parameter = 0;
1370                         if (le_conn_interval_max > existing_range.le_conn_interval_max) update_parameter = 0;
1371 
1372                         if (le_conn_latency < existing_range.le_conn_latency_min) update_parameter = 0;
1373                         if (le_conn_latency > existing_range.le_conn_latency_max) update_parameter = 0;
1374 
1375                         if (le_supervision_timeout < existing_range.le_supervision_timeout_min) update_parameter = 0;
1376                         if (le_supervision_timeout > existing_range.le_supervision_timeout_max) update_parameter = 0;
1377 
1378                         if (update_parameter){
1379                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_SEND_RESPONSE;
1380                             connection->le_conn_interval_min = le_conn_interval_min;
1381                             connection->le_conn_interval_max = le_conn_interval_max;
1382                             connection->le_conn_latency = le_conn_latency;
1383                             connection->le_supervision_timeout = le_supervision_timeout;
1384                         } else {
1385                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_DENY;
1386                         }
1387                         connection->le_con_param_update_identifier = packet[COMPLETE_L2CAP_HEADER + 1];
1388                     }
1389 
1390                     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
1391                     (*packet_handler)( HCI_EVENT_PACKET, 0, event, sizeof(event));
1392 
1393                     break;
1394                 }
1395                 default: {
1396                     uint8_t sig_id = packet[COMPLETE_L2CAP_HEADER + 1];
1397                     l2cap_register_signaling_response(handle, COMMAND_REJECT_LE, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1398                     break;
1399                 }
1400             }
1401             break;
1402         }
1403 
1404         default: {
1405             // Find channel for this channel_id and connection handle
1406             l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(channel_id);
1407             if (channel) {
1408                 l2cap_dispatch_to_channel(channel, L2CAP_DATA_PACKET, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1409             }
1410             break;
1411         }
1412     }
1413 
1414     l2cap_run();
1415 }
1416 
1417 // finalize closed channel - l2cap_handle_disconnect_request & DISCONNECTION_RESPONSE
1418 void l2cap_finialize_channel_close(l2cap_channel_t *channel){
1419     channel->state = L2CAP_STATE_CLOSED;
1420     l2cap_emit_channel_closed(channel);
1421     // discard channel
1422     l2cap_stop_rtx(channel);
1423     btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
1424     btstack_memory_l2cap_channel_free(channel);
1425 }
1426 
1427 static l2cap_service_t * l2cap_get_service_internal(btstack_linked_list_t * services, uint16_t psm){
1428     btstack_linked_list_iterator_t it;
1429     btstack_linked_list_iterator_init(&it, services);
1430     while (btstack_linked_list_iterator_has_next(&it)){
1431         l2cap_service_t * service = (l2cap_service_t *) btstack_linked_list_iterator_next(&it);
1432         if ( service->psm == psm){
1433             return service;
1434         };
1435     }
1436     return NULL;
1437 }
1438 
1439 static inline l2cap_service_t * l2cap_get_service(uint16_t psm){
1440     return l2cap_get_service_internal(&l2cap_services, psm);
1441 }
1442 
1443 
1444 uint8_t l2cap_register_service(btstack_packet_handler_t service_packet_handler, uint16_t psm, uint16_t mtu, gap_security_level_t security_level){
1445 
1446     log_info("L2CAP_REGISTER_SERVICE psm 0x%x mtu %u", psm, mtu);
1447 
1448     // check for alread registered psm
1449     // TODO: emit error event
1450     l2cap_service_t *service = l2cap_get_service(psm);
1451     if (service) {
1452         log_error("l2cap_register_service: PSM %u already registered", psm);
1453         return L2CAP_SERVICE_ALREADY_REGISTERED;
1454     }
1455 
1456     // alloc structure
1457     // TODO: emit error event
1458     service = btstack_memory_l2cap_service_get();
1459     if (!service) {
1460         log_error("l2cap_register_service: no memory for l2cap_service_t");
1461         return BTSTACK_MEMORY_ALLOC_FAILED;
1462     }
1463 
1464     // fill in
1465     service->psm = psm;
1466     service->mtu = mtu;
1467     service->packet_handler = service_packet_handler;
1468     service->required_security_level = security_level;
1469 
1470     // add to services list
1471     btstack_linked_list_add(&l2cap_services, (btstack_linked_item_t *) service);
1472 
1473     // enable page scan
1474     hci_connectable_control(1);
1475 
1476     return 0;
1477 }
1478 
1479 void l2cap_unregister_service(uint16_t psm){
1480 
1481     log_info("L2CAP_UNREGISTER_SERVICE psm 0x%x", psm);
1482 
1483     l2cap_service_t *service = l2cap_get_service(psm);
1484     if (!service) return;
1485     btstack_linked_list_remove(&l2cap_services, (btstack_linked_item_t *) service);
1486     btstack_memory_l2cap_service_free(service);
1487 
1488     // disable page scan when no services registered
1489     if (!btstack_linked_list_empty(&l2cap_services)) return;
1490     hci_connectable_control(0);
1491 }
1492 
1493 // Bluetooth 4.0 - allows to register handler for Attribute Protocol and Security Manager Protocol
1494 void l2cap_register_fixed_channel(btstack_packet_handler_t the_packet_handler, uint16_t channel_id) {
1495     switch(channel_id){
1496         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
1497             attribute_protocol_packet_handler = the_packet_handler;
1498             break;
1499         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
1500             security_protocol_packet_handler = the_packet_handler;
1501             break;
1502         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
1503             connectionless_channel_packet_handler = the_packet_handler;
1504             break;
1505     }
1506 }
1507 
1508 #ifdef ENABLE_BLE
1509 
1510 
1511 #if 0
1512 static inline l2cap_service_t * l2cap_le_get_service(uint16_t psm){
1513     return l2cap_get_service_internal(&l2cap_le_services, psm);
1514 }
1515 /**
1516  * @brief Regster L2CAP LE Credit Based Flow Control Mode service
1517  * @param
1518  */
1519 void l2cap_le_register_service(btstack_packet_handler_t packet_handler, uint16_t psm,
1520     uint16_t mtu, uint16_t mps, uint16_t initial_credits, gap_security_level_t security_level){
1521 
1522     log_info("L2CAP_LE_REGISTER_SERVICE psm 0x%x mtu %u connection %p", psm, mtu, connection);
1523 
1524     // check for alread registered psm
1525     // TODO: emit error event
1526     l2cap_service_t *service = l2cap_le_get_service(psm);
1527     if (service) {
1528         log_error("l2cap_le_register_service_internal: PSM %u already registered", psm);
1529         l2cap_emit_service_registered(connection, L2CAP_SERVICE_ALREADY_REGISTERED, psm);
1530         return;
1531     }
1532 
1533     // alloc structure
1534     // TODO: emit error event
1535     service = btstack_memory_l2cap_service_get();
1536     if (!service) {
1537         log_error("l2cap_register_service_internal: no memory for l2cap_service_t");
1538         l2cap_emit_service_registered(connection, BTSTACK_MEMORY_ALLOC_FAILED, psm);
1539         return;
1540     }
1541 
1542     // fill in
1543     service->psm = psm;
1544     service->mtu = mtu;
1545     service->mps = mps;
1546     service->packet_handler = packet_handler;
1547     service->required_security_level = security_level;
1548 
1549     // add to services list
1550     btstack_linked_list_add(&l2cap_le_services, (btstack_linked_item_t *) service);
1551 
1552     // done
1553     l2cap_emit_service_registered(connection, 0, psm);
1554 }
1555 
1556 void l2cap_le_unregister_service(uint16_t psm) {
1557 
1558     log_info("L2CAP_LE_UNREGISTER_SERVICE psm 0x%x", psm);
1559 
1560     l2cap_service_t *service = l2cap_le_get_service(psm);
1561     if (!service) return;
1562     btstack_linked_list_remove(&l2cap_le_services, (btstack_linked_item_t *) service);
1563     btstack_memory_l2cap_service_free(service);
1564 }
1565 #endif
1566 #endif
1567