xref: /btstack/src/l2cap.c (revision 2125de09632edbd687e6b09dd1566fe517285732)
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(l2cap_channel_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 btstack_packet_handler_t fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL];
108 // static btstack_packet_handler_t fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL];
109 // static btstack_packet_handler_t fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL];
110 
111 static int l2cap_fixed_channel_table_index_for_channel_id(uint16_t channel_id){
112     switch (channel_id){
113         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
114             return L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL;
115         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
116             return  L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL;
117         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
118             return  L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL;
119         default:
120             return -1;
121         }
122 }
123 
124 void l2cap_init(void){
125     signaling_responses_pending = 0;
126 
127     l2cap_channels = NULL;
128     l2cap_services = NULL;
129     l2cap_le_services = NULL;
130     l2cap_le_channels = NULL;
131 
132     l2cap_event_packet_handler = NULL;
133     memset(fixed_channels, 0, sizeof(fixed_channels));
134 
135     require_security_level2_for_outgoing_sdp = 0;
136 
137     //
138     // register callback with HCI
139     //
140     hci_event_callback_registration.callback = &l2cap_hci_event_handler;
141     hci_add_event_handler(&hci_event_callback_registration);
142 
143     hci_register_acl_packet_handler(&l2cap_acl_handler);
144 
145     hci_connectable_control(0); // no services yet
146 }
147 
148 void l2cap_register_packet_handler(void (*handler)(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size)){
149     l2cap_event_packet_handler = handler;
150 }
151 
152 static void l2cap_dispatch_to_channel(l2cap_channel_t *channel, uint8_t type, uint8_t * data, uint16_t size){
153     (* (channel->packet_handler))(type, channel->local_cid, data, size);
154 }
155 
156 void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status) {
157     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",
158              status, bd_addr_to_str(channel->address), channel->handle, channel->psm,
159              channel->local_cid, channel->remote_cid, channel->local_mtu, channel->remote_mtu, channel->flush_timeout);
160     uint8_t event[23];
161     event[0] = L2CAP_EVENT_CHANNEL_OPENED;
162     event[1] = sizeof(event) - 2;
163     event[2] = status;
164     bt_flip_addr(&event[3], channel->address);
165     little_endian_store_16(event,  9, channel->handle);
166     little_endian_store_16(event, 11, channel->psm);
167     little_endian_store_16(event, 13, channel->local_cid);
168     little_endian_store_16(event, 15, channel->remote_cid);
169     little_endian_store_16(event, 17, channel->local_mtu);
170     little_endian_store_16(event, 19, channel->remote_mtu);
171     little_endian_store_16(event, 21, channel->flush_timeout);
172     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
173     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
174 
175     // if channel opened successfully, also send can send now if possible
176     if (status) return;
177     if (hci_can_send_acl_packet_now(channel->handle)){
178         l2cap_emit_can_send_now(channel);
179     } else {
180         channel->waiting_for_can_send_now = 1;
181     }
182 }
183 
184 void l2cap_emit_channel_closed(l2cap_channel_t *channel) {
185     log_info("L2CAP_EVENT_CHANNEL_CLOSED local_cid 0x%x", channel->local_cid);
186     uint8_t event[4];
187     event[0] = L2CAP_EVENT_CHANNEL_CLOSED;
188     event[1] = sizeof(event) - 2;
189     little_endian_store_16(event, 2, channel->local_cid);
190     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
191     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
192 }
193 
194 void l2cap_emit_connection_request(l2cap_channel_t *channel) {
195     log_info("L2CAP_EVENT_INCOMING_CONNECTION addr %s handle 0x%x psm 0x%x local_cid 0x%x remote_cid 0x%x",
196              bd_addr_to_str(channel->address), channel->handle,  channel->psm, channel->local_cid, channel->remote_cid);
197     uint8_t event[16];
198     event[0] = L2CAP_EVENT_INCOMING_CONNECTION;
199     event[1] = sizeof(event) - 2;
200     bt_flip_addr(&event[2], channel->address);
201     little_endian_store_16(event,  8, channel->handle);
202     little_endian_store_16(event, 10, channel->psm);
203     little_endian_store_16(event, 12, channel->local_cid);
204     little_endian_store_16(event, 14, channel->remote_cid);
205     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
206     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
207 }
208 
209 static void l2cap_emit_can_send_now(l2cap_channel_t *channel) {
210     log_info("L2CAP_EVENT_CHANNEL_CAN_SEND_NOW local_cid 0x%x", channel->local_cid);
211     uint8_t event[4];
212     event[0] = L2CAP_EVENT_CAN_SEND_NOW;
213     event[1] = sizeof(event) - 2;
214     little_endian_store_16(event, 2, channel->local_cid);
215     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
216     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
217 }
218 
219 static void l2cap_emit_connection_parameter_update_response(uint16_t handle, uint16_t result){
220     uint8_t event[6];
221     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_RESPONSE;
222     event[1] = 4;
223     little_endian_store_16(event, 2, handle);
224     little_endian_store_16(event, 4, result);
225     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
226     if (!l2cap_event_packet_handler) return;
227     (*l2cap_event_packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
228 }
229 
230 static l2cap_channel_t * l2cap_get_channel_for_local_cid(uint16_t local_cid){
231     btstack_linked_list_iterator_t it;
232     btstack_linked_list_iterator_init(&it, &l2cap_channels);
233     while (btstack_linked_list_iterator_has_next(&it)){
234         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
235         if ( channel->local_cid == local_cid) {
236             return channel;
237         }
238     }
239     return NULL;
240 }
241 
242 int  l2cap_can_send_packet_now(uint16_t local_cid){
243     l2cap_channel_t *channel = l2cap_get_channel_for_local_cid(local_cid);
244     if (!channel) return 0;
245     int can_send = hci_can_send_acl_packet_now(channel->handle);
246     if (!can_send){
247         channel->waiting_for_can_send_now = 1;
248     }
249     return can_send;
250 }
251 
252 int  l2cap_can_send_prepared_packet_now(uint16_t local_cid){
253     l2cap_channel_t *channel = l2cap_get_channel_for_local_cid(local_cid);
254     if (!channel) return 0;
255     int can_send = hci_can_send_prepared_acl_packet_now(channel->handle);
256     if (!can_send){
257         channel->waiting_for_can_send_now = 1;
258     }
259     return can_send;
260 }
261 
262 int  l2cap_can_send_fixed_channel_packet_now(uint16_t handle, uint16_t channel_id){
263     int can_send = hci_can_send_acl_packet_now(handle);
264     if (!can_send){
265         int index = l2cap_fixed_channel_table_index_for_channel_id(channel_id);
266         if (index >= 0){
267             fixed_channels[index].waiting_for_can_send_now = 1;
268         }
269     }
270     return can_send;
271 }
272 
273 uint16_t l2cap_get_remote_mtu_for_local_cid(uint16_t local_cid){
274     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
275     if (channel) {
276         return channel->remote_mtu;
277     }
278     return 0;
279 }
280 
281 static l2cap_channel_t * l2cap_channel_for_rtx_timer(btstack_timer_source_t * ts){
282     btstack_linked_list_iterator_t it;
283     btstack_linked_list_iterator_init(&it, &l2cap_channels);
284     while (btstack_linked_list_iterator_has_next(&it)){
285         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
286         if ( &channel->rtx == ts) {
287             return channel;
288         }
289     }
290     return NULL;
291 }
292 
293 static void l2cap_rtx_timeout(btstack_timer_source_t * ts){
294     l2cap_channel_t * channel = l2cap_channel_for_rtx_timer(ts);
295     if (!ts) return;
296 
297     log_info("l2cap_rtx_timeout for local cid 0x%02x", channel->local_cid);
298 
299     // "When terminating the channel, it is not necessary to send a L2CAP_DisconnectReq
300     //  and enter WAIT_DISCONNECT state. Channels can be transitioned directly to the CLOSED state."
301     // notify client
302     l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_RTX_TIMEOUT);
303 
304     // discard channel
305     // no need to stop timer here, it is removed from list during timer callback
306     btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
307     btstack_memory_l2cap_channel_free(channel);
308 }
309 
310 static void l2cap_stop_rtx(l2cap_channel_t * channel){
311     log_info("l2cap_stop_rtx for local cid 0x%02x", channel->local_cid);
312     btstack_run_loop_remove_timer(&channel->rtx);
313 }
314 
315 static void l2cap_start_rtx(l2cap_channel_t * channel){
316     l2cap_stop_rtx(channel);
317     log_info("l2cap_start_rtx for local cid 0x%02x", channel->local_cid);
318     btstack_run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
319     btstack_run_loop_set_timer(&channel->rtx, L2CAP_RTX_TIMEOUT_MS);
320     btstack_run_loop_add_timer(&channel->rtx);
321 }
322 
323 static void l2cap_start_ertx(l2cap_channel_t * channel){
324     log_info("l2cap_start_ertx for local cid 0x%02x", channel->local_cid);
325     l2cap_stop_rtx(channel);
326     btstack_run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
327     btstack_run_loop_set_timer(&channel->rtx, L2CAP_ERTX_TIMEOUT_MS);
328     btstack_run_loop_add_timer(&channel->rtx);
329 }
330 
331 void l2cap_require_security_level_2_for_outgoing_sdp(void){
332     require_security_level2_for_outgoing_sdp = 1;
333 }
334 
335 static int l2cap_security_level_0_allowed_for_PSM(uint16_t psm){
336     return (psm == PSM_SDP) && (!require_security_level2_for_outgoing_sdp);
337 }
338 
339 static int l2cap_send_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
340 
341     if (!hci_can_send_acl_packet_now(handle)){
342         log_info("l2cap_send_signaling_packet, cannot send");
343         return BTSTACK_ACL_BUFFERS_FULL;
344     }
345 
346     // log_info("l2cap_send_signaling_packet type %u", cmd);
347     hci_reserve_packet_buffer();
348     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
349     va_list argptr;
350     va_start(argptr, identifier);
351     uint16_t len = l2cap_create_signaling_classic(acl_buffer, handle, cmd, identifier, argptr);
352     va_end(argptr);
353     // log_info("l2cap_send_signaling_packet con %u!", handle);
354     return hci_send_acl_packet_buffer(len);
355 }
356 
357 #ifdef ENABLE_BLE
358 static int l2cap_send_le_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
359 
360     if (!hci_can_send_acl_packet_now(handle)){
361         log_info("l2cap_send_signaling_packet, cannot send");
362         return BTSTACK_ACL_BUFFERS_FULL;
363     }
364 
365     // log_info("l2cap_send_signaling_packet type %u", cmd);
366     hci_reserve_packet_buffer();
367     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
368     va_list argptr;
369     va_start(argptr, identifier);
370     uint16_t len = l2cap_create_signaling_le(acl_buffer, handle, cmd, identifier, argptr);
371     va_end(argptr);
372     // log_info("l2cap_send_signaling_packet con %u!", handle);
373     return hci_send_acl_packet_buffer(len);
374 }
375 #endif
376 
377 uint8_t *l2cap_get_outgoing_buffer(void){
378     return hci_get_outgoing_packet_buffer() + COMPLETE_L2CAP_HEADER; // 8 bytes
379 }
380 
381 int l2cap_reserve_packet_buffer(void){
382     return hci_reserve_packet_buffer();
383 }
384 
385 void l2cap_release_packet_buffer(void){
386     hci_release_packet_buffer();
387 }
388 
389 
390 int l2cap_send_prepared(uint16_t local_cid, uint16_t len){
391 
392     if (!hci_is_packet_buffer_reserved()){
393         log_error("l2cap_send_prepared called without reserving packet first");
394         return BTSTACK_ACL_BUFFERS_FULL;
395     }
396 
397     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
398     if (!channel) {
399         log_error("l2cap_send_prepared no channel for cid 0x%02x", local_cid);
400         return -1;   // TODO: define error
401     }
402 
403     if (!hci_can_send_prepared_acl_packet_now(channel->handle)){
404         log_info("l2cap_send_prepared cid 0x%02x, cannot send", local_cid);
405         return BTSTACK_ACL_BUFFERS_FULL;
406     }
407 
408     log_debug("l2cap_send_prepared cid 0x%02x, handle %u, 1 credit used", local_cid, channel->handle);
409 
410     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
411 
412     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
413 
414     // 0 - Connection handle : PB=pb : BC=00
415     little_endian_store_16(acl_buffer, 0, channel->handle | (pb << 12) | (0 << 14));
416     // 2 - ACL length
417     little_endian_store_16(acl_buffer, 2,  len + 4);
418     // 4 - L2CAP packet length
419     little_endian_store_16(acl_buffer, 4,  len + 0);
420     // 6 - L2CAP channel DEST
421     little_endian_store_16(acl_buffer, 6, channel->remote_cid);
422     // send
423     int err = hci_send_acl_packet_buffer(len+8);
424 
425     return err;
426 }
427 
428 int l2cap_send_prepared_connectionless(uint16_t handle, uint16_t cid, uint16_t len){
429 
430     if (!hci_is_packet_buffer_reserved()){
431         log_error("l2cap_send_prepared_connectionless called without reserving packet first");
432         return BTSTACK_ACL_BUFFERS_FULL;
433     }
434 
435     if (!hci_can_send_prepared_acl_packet_now(handle)){
436         log_info("l2cap_send_prepared_connectionless handle 0x%02x, cid 0x%02x, cannot send", handle, cid);
437         return BTSTACK_ACL_BUFFERS_FULL;
438     }
439 
440     log_debug("l2cap_send_prepared_connectionless handle %u, cid 0x%02x", handle, cid);
441 
442     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
443 
444     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
445 
446     // 0 - Connection handle : PB=pb : BC=00
447     little_endian_store_16(acl_buffer, 0, handle | (pb << 12) | (0 << 14));
448     // 2 - ACL length
449     little_endian_store_16(acl_buffer, 2,  len + 4);
450     // 4 - L2CAP packet length
451     little_endian_store_16(acl_buffer, 4,  len + 0);
452     // 6 - L2CAP channel DEST
453     little_endian_store_16(acl_buffer, 6, cid);
454     // send
455     int err = hci_send_acl_packet_buffer(len+8);
456 
457     return err;
458 }
459 
460 int l2cap_send(uint16_t local_cid, uint8_t *data, uint16_t len){
461 
462     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
463     if (!channel) {
464         log_error("l2cap_send no channel for cid 0x%02x", local_cid);
465         return -1;   // TODO: define error
466     }
467 
468     if (len > channel->remote_mtu){
469         log_error("l2cap_send cid 0x%02x, data length exceeds remote MTU.", local_cid);
470         return L2CAP_DATA_LEN_EXCEEDS_REMOTE_MTU;
471     }
472 
473     if (!hci_can_send_acl_packet_now(channel->handle)){
474         log_info("l2cap_send cid 0x%02x, cannot send", local_cid);
475         return BTSTACK_ACL_BUFFERS_FULL;
476     }
477 
478     hci_reserve_packet_buffer();
479     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
480 
481     memcpy(&acl_buffer[8], data, len);
482 
483     return l2cap_send_prepared(local_cid, len);
484 }
485 
486 int l2cap_send_connectionless(uint16_t handle, uint16_t cid, uint8_t *data, uint16_t len){
487 
488     if (!hci_can_send_acl_packet_now(handle)){
489         log_info("l2cap_send cid 0x%02x, cannot send", cid);
490         return BTSTACK_ACL_BUFFERS_FULL;
491     }
492 
493     hci_reserve_packet_buffer();
494     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
495 
496     memcpy(&acl_buffer[8], data, len);
497 
498     return l2cap_send_prepared_connectionless(handle, cid, len);
499 }
500 
501 int l2cap_send_echo_request(uint16_t handle, uint8_t *data, uint16_t len){
502     return l2cap_send_signaling_packet(handle, ECHO_REQUEST, 0x77, len, data);
503 }
504 
505 static inline void channelStateVarSetFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
506     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var | flag);
507 }
508 
509 static inline void channelStateVarClearFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
510     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var & ~flag);
511 }
512 
513 
514 
515 // MARK: L2CAP_RUN
516 // process outstanding signaling tasks
517 static void l2cap_run(void){
518 
519     // log_info("l2cap_run: entered");
520 
521     // check pending signaling responses
522     while (signaling_responses_pending){
523 
524         hci_con_handle_t handle = signaling_responses[0].handle;
525 
526         if (!hci_can_send_acl_packet_now(handle)) break;
527 
528         uint8_t  sig_id = signaling_responses[0].sig_id;
529         uint16_t infoType = signaling_responses[0].data;    // INFORMATION_REQUEST
530         uint16_t result   = signaling_responses[0].data;    // CONNECTION_REQUEST, COMMAND_REJECT
531         uint8_t  response_code = signaling_responses[0].code;
532 
533         // remove first item before sending (to avoid sending response mutliple times)
534         signaling_responses_pending--;
535         int i;
536         for (i=0; i < signaling_responses_pending; i++){
537             memcpy(&signaling_responses[i], &signaling_responses[i+1], sizeof(l2cap_signaling_response_t));
538         }
539 
540         switch (response_code){
541             case CONNECTION_REQUEST:
542                 l2cap_send_signaling_packet(handle, CONNECTION_RESPONSE, sig_id, 0, 0, result, 0);
543                 // also disconnect if result is 0x0003 - security blocked
544                 if (result == 0x0003){
545                     hci_disconnect_security_block(handle);
546                 }
547                 break;
548             case ECHO_REQUEST:
549                 l2cap_send_signaling_packet(handle, ECHO_RESPONSE, sig_id, 0, NULL);
550                 break;
551             case INFORMATION_REQUEST:
552                 switch (infoType){
553                     case 1: { // Connectionless MTU
554                         uint16_t connectionless_mtu = hci_max_acl_data_packet_length();
555                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(connectionless_mtu), &connectionless_mtu);
556                         break;
557                     }
558                     case 2: { // Extended Features Supported
559                         // extended features request supported, features: fixed channels, unicast connectionless data reception
560                         uint32_t features = 0x280;
561                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(features), &features);
562                         break;
563                     }
564                     case 3: { // Fixed Channels Supported
565                         uint8_t map[8];
566                         memset(map, 0, 8);
567                         map[0] = 0x01;  // L2CAP Signaling Channel (0x01) + Connectionless reception (0x02)
568                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(map), &map);
569                         break;
570                     }
571                     default:
572                         // all other types are not supported
573                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 1, 0, NULL);
574                         break;
575                 }
576                 break;
577             case COMMAND_REJECT:
578                 l2cap_send_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
579 #ifdef ENABLE_BLE
580             case COMMAND_REJECT_LE:
581                 l2cap_send_le_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
582                 break;
583 #endif
584             default:
585                 // should not happen
586                 break;
587         }
588     }
589 
590     uint8_t  config_options[4];
591     btstack_linked_list_iterator_t it;
592     btstack_linked_list_iterator_init(&it, &l2cap_channels);
593     while (btstack_linked_list_iterator_has_next(&it)){
594 
595         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
596         // log_info("l2cap_run: channel %p, state %u, var 0x%02x", channel, channel->state, channel->state_var);
597         switch (channel->state){
598 
599             case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
600             case L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT:
601                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
602                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND) {
603                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND);
604                     l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 1, 0);
605                 }
606                 break;
607 
608             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
609                 if (!hci_can_send_command_packet_now()) break;
610                 // send connection request - set state first
611                 channel->state = L2CAP_STATE_WAIT_CONNECTION_COMPLETE;
612                 // BD_ADDR, Packet_Type, Page_Scan_Repetition_Mode, Reserved, Clock_Offset, Allow_Role_Switch
613                 hci_send_cmd(&hci_create_connection, channel->address, hci_usable_acl_packet_types(), 0, 0, 0, 1);
614                 break;
615 
616             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE:
617                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
618                 channel->state = L2CAP_STATE_INVALID;
619                 l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, channel->reason, 0);
620                 // discard channel - l2cap_finialize_channel_close without sending l2cap close event
621                 l2cap_stop_rtx(channel);
622                 btstack_linked_list_iterator_remove(&it);
623                 btstack_memory_l2cap_channel_free(channel);
624                 break;
625 
626             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT:
627                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
628                 channel->state = L2CAP_STATE_CONFIG;
629                 channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
630                 l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 0, 0);
631                 break;
632 
633             case L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST:
634                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
635                 // success, start l2cap handshake
636                 channel->local_sig_id = l2cap_next_sig_id();
637                 channel->state = L2CAP_STATE_WAIT_CONNECT_RSP;
638                 l2cap_send_signaling_packet( channel->handle, CONNECTION_REQUEST, channel->local_sig_id, channel->psm, channel->local_cid);
639                 l2cap_start_rtx(channel);
640                 break;
641 
642             case L2CAP_STATE_CONFIG:
643                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
644                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP){
645                     uint16_t flags = 0;
646                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
647                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT) {
648                         flags = 1;
649                     } else {
650                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP);
651                     }
652                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID){
653                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, L2CAP_CONF_RESULT_UNKNOWN_OPTIONS, 0, NULL);
654                     } else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU){
655                         config_options[0] = 1; // MTU
656                         config_options[1] = 2; // len param
657                         little_endian_store_16( (uint8_t*)&config_options, 2, channel->remote_mtu);
658                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 4, &config_options);
659                         channelStateVarClearFlag(channel,L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
660                     } else {
661                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 0, NULL);
662                     }
663                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
664                 }
665                 else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ){
666                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
667                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_REQ);
668                     channel->local_sig_id = l2cap_next_sig_id();
669                     config_options[0] = 1; // MTU
670                     config_options[1] = 2; // len param
671                     little_endian_store_16( (uint8_t*)&config_options, 2, channel->local_mtu);
672                     l2cap_send_signaling_packet(channel->handle, CONFIGURE_REQUEST, channel->local_sig_id, channel->remote_cid, 0, 4, &config_options);
673                     l2cap_start_rtx(channel);
674                 }
675                 if (l2cap_channel_ready_for_open(channel)){
676                     channel->state = L2CAP_STATE_OPEN;
677                     l2cap_emit_channel_opened(channel, 0);  // success
678                 }
679                 break;
680 
681             case L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE:
682                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
683                 channel->state = L2CAP_STATE_INVALID;
684                 l2cap_send_signaling_packet( channel->handle, DISCONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid);
685                 // 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 :)
686                 l2cap_finialize_channel_close(channel);  // -- remove from list
687                 break;
688 
689             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
690                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
691                 channel->local_sig_id = l2cap_next_sig_id();
692                 channel->state = L2CAP_STATE_WAIT_DISCONNECT;
693                 l2cap_send_signaling_packet( channel->handle, DISCONNECTION_REQUEST, channel->local_sig_id, channel->remote_cid, channel->local_cid);
694                 break;
695             default:
696                 break;
697         }
698     }
699 
700 #ifdef ENABLE_BLE
701     // send l2cap con paramter update if necessary
702     hci_connections_get_iterator(&it);
703     while(btstack_linked_list_iterator_has_next(&it)){
704         hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it);
705         if (connection->address_type != BD_ADDR_TYPE_LE_PUBLIC && connection->address_type != BD_ADDR_TYPE_LE_RANDOM) continue;
706         if (!hci_can_send_acl_packet_now(connection->con_handle)) continue;
707         switch (connection->le_con_parameter_update_state){
708             case CON_PARAMETER_UPDATE_SEND_REQUEST:
709                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_NONE;
710                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_REQUEST, connection->le_con_param_update_identifier,
711                                                connection->le_conn_interval_min, connection->le_conn_interval_max, connection->le_conn_latency, connection->le_supervision_timeout);
712                 break;
713             case CON_PARAMETER_UPDATE_SEND_RESPONSE:
714                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_CHANGE_HCI_CON_PARAMETERS;
715                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_RESPONSE, connection->le_con_param_update_identifier, 0);
716                 break;
717             case CON_PARAMETER_UPDATE_DENY:
718                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_NONE;
719                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_RESPONSE, connection->le_con_param_update_identifier, 1);
720                 break;
721             default:
722                 break;
723         }
724     }
725 #endif
726 
727     // log_info("l2cap_run: exit");
728 }
729 
730 uint16_t l2cap_max_mtu(void){
731     return HCI_ACL_PAYLOAD_SIZE - L2CAP_HEADER_SIZE;
732 }
733 
734 uint16_t l2cap_max_le_mtu(void){
735     return l2cap_max_mtu();
736 }
737 
738 static void l2cap_handle_connection_complete(uint16_t handle, l2cap_channel_t * channel){
739     if (channel->state == L2CAP_STATE_WAIT_CONNECTION_COMPLETE || channel->state == L2CAP_STATE_WILL_SEND_CREATE_CONNECTION) {
740         log_info("l2cap_handle_connection_complete expected state");
741         // success, start l2cap handshake
742         channel->handle = handle;
743         // check remote SSP feature first
744         channel->state = L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES;
745     }
746 }
747 
748 static void l2cap_handle_remote_supported_features_received(l2cap_channel_t * channel){
749     if (channel->state != L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES) return;
750 
751     // we have been waiting for remote supported features, if both support SSP,
752     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));
753     if (hci_ssp_supported_on_both_sides(channel->handle) && !l2cap_security_level_0_allowed_for_PSM(channel->psm)){
754         // request security level 2
755         channel->state = L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE;
756         gap_request_security_level(channel->handle, LEVEL_2);
757         return;
758     }
759     // fine, go ahead
760     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
761 }
762 
763 /**
764  * @brief Creates L2CAP channel to the PSM of a remote device with baseband address. A new baseband connection will be initiated if necessary.
765  * @param packet_handler
766  * @param address
767  * @param psm
768  * @param mtu
769  * @param local_cid
770  */
771 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){
772     log_info("L2CAP_CREATE_CHANNEL addr %s psm 0x%x mtu %u", bd_addr_to_str(address), psm, mtu);
773 
774     // alloc structure
775     l2cap_channel_t * chan = btstack_memory_l2cap_channel_get();
776     if (!chan) {
777         return BTSTACK_MEMORY_ALLOC_FAILED;
778     }
779 
780      // Init memory (make valgrind happy)
781     memset(chan, 0, sizeof(l2cap_channel_t));
782     // limit local mtu to max acl packet length - l2cap header
783     if (mtu > l2cap_max_mtu()) {
784         mtu = l2cap_max_mtu();
785     }
786 
787     // fill in
788     BD_ADDR_COPY(chan->address, address);
789     chan->psm = psm;
790     chan->handle = 0;
791     chan->packet_handler = channel_packet_handler;
792     chan->remote_mtu = L2CAP_MINIMAL_MTU;
793     chan->local_mtu = mtu;
794     chan->local_cid = l2cap_next_local_cid();
795 
796     // set initial state
797     chan->state = L2CAP_STATE_WILL_SEND_CREATE_CONNECTION;
798     chan->state_var = L2CAP_CHANNEL_STATE_VAR_NONE;
799     chan->remote_sig_id = L2CAP_SIG_ID_INVALID;
800     chan->local_sig_id = L2CAP_SIG_ID_INVALID;
801     chan->required_security_level = LEVEL_0;
802 
803     // add to connections list
804     btstack_linked_list_add(&l2cap_channels, (btstack_linked_item_t *) chan);
805 
806     // store local_cid
807     if (out_local_cid){
808        *out_local_cid = chan->local_cid;
809     }
810 
811     // check if hci connection is already usable
812     hci_connection_t * conn = hci_connection_for_bd_addr_and_type(address, BD_ADDR_TYPE_CLASSIC);
813     if (conn){
814         log_info("l2cap_create_channel, hci connection already exists");
815         l2cap_handle_connection_complete(conn->con_handle, chan);
816         // check if remote supported fearures are already received
817         if (conn->bonding_flags & BONDING_RECEIVED_REMOTE_FEATURES) {
818             l2cap_handle_remote_supported_features_received(chan);
819         }
820     }
821 
822     l2cap_run();
823 
824     return 0;
825 }
826 
827 void
828 l2cap_disconnect(uint16_t local_cid, uint8_t reason){
829     log_info("L2CAP_DISCONNECT local_cid 0x%x reason 0x%x", local_cid, reason);
830     // find channel for local_cid
831     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
832     if (channel) {
833         channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST;
834     }
835     // process
836     l2cap_run();
837 }
838 
839 static void l2cap_handle_connection_failed_for_addr(bd_addr_t address, uint8_t status){
840     btstack_linked_list_iterator_t it;
841     btstack_linked_list_iterator_init(&it, &l2cap_channels);
842     while (btstack_linked_list_iterator_has_next(&it)){
843         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
844         if ( BD_ADDR_CMP( channel->address, address) != 0) continue;
845         // channel for this address found
846         switch (channel->state){
847             case L2CAP_STATE_WAIT_CONNECTION_COMPLETE:
848             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
849                 // failure, forward error code
850                 l2cap_emit_channel_opened(channel, status);
851                 // discard channel
852                 l2cap_stop_rtx(channel);
853                 btstack_linked_list_iterator_remove(&it);
854                 btstack_memory_l2cap_channel_free(channel);
855                 break;
856             default:
857                 break;
858         }
859     }
860 }
861 
862 static void l2cap_handle_connection_success_for_addr(bd_addr_t address, hci_con_handle_t handle){
863     btstack_linked_list_iterator_t it;
864     btstack_linked_list_iterator_init(&it, &l2cap_channels);
865     while (btstack_linked_list_iterator_has_next(&it)){
866         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
867         if ( ! BD_ADDR_CMP( channel->address, address) ){
868             l2cap_handle_connection_complete(handle, channel);
869         }
870     }
871     // process
872     l2cap_run();
873 }
874 
875 static void l2cap_notify_channel_can_send(void){
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 (!channel->waiting_for_can_send_now) continue;
881         if (!hci_can_send_acl_packet_now(channel->handle)) continue;
882         channel->waiting_for_can_send_now = 0;
883         l2cap_emit_can_send_now(channel);
884     }
885 
886     int i;
887     for (i=0;i<L2CAP_FIXED_CHANNEL_TABLE_SIZE;i++){
888         if (!fixed_channels[i].waiting_for_can_send_now) continue;
889         // can we send now?
890         //
891 
892     }
893 }
894 
895 static void l2cap_hci_event_handler(uint8_t packet_type, uint16_t cid, uint8_t *packet, uint16_t size){
896 
897     bd_addr_t address;
898     hci_con_handle_t handle;
899     btstack_linked_list_iterator_t it;
900     int hci_con_used;
901 
902     switch(packet[0]){
903 
904         // handle connection complete events
905         case HCI_EVENT_CONNECTION_COMPLETE:
906             bt_flip_addr(address, &packet[5]);
907             if (packet[2] == 0){
908                 handle = little_endian_read_16(packet, 3);
909                 l2cap_handle_connection_success_for_addr(address, handle);
910             } else {
911                 l2cap_handle_connection_failed_for_addr(address, packet[2]);
912             }
913             break;
914 
915         // handle successful create connection cancel command
916         case HCI_EVENT_COMMAND_COMPLETE:
917             if ( COMMAND_COMPLETE_EVENT(packet, hci_create_connection_cancel) ) {
918                 if (packet[5] == 0){
919                     bt_flip_addr(address, &packet[6]);
920                     // CONNECTION TERMINATED BY LOCAL HOST (0X16)
921                     l2cap_handle_connection_failed_for_addr(address, 0x16);
922                 }
923             }
924             l2cap_run();    // try sending signaling packets first
925             break;
926 
927         case HCI_EVENT_COMMAND_STATUS:
928             l2cap_run();    // try sending signaling packets first
929             break;
930 
931         // handle disconnection complete events
932         case HCI_EVENT_DISCONNECTION_COMPLETE:
933             // send l2cap disconnect events for all channels on this handle and free them
934             handle = little_endian_read_16(packet, 3);
935             btstack_linked_list_iterator_init(&it, &l2cap_channels);
936             while (btstack_linked_list_iterator_has_next(&it)){
937                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
938                 if (channel->handle != handle) continue;
939                 l2cap_emit_channel_closed(channel);
940                 l2cap_stop_rtx(channel);
941                 btstack_linked_list_iterator_remove(&it);
942                 btstack_memory_l2cap_channel_free(channel);
943             }
944             break;
945 
946         // Notify channel packet handler if they can send now
947         case DAEMON_EVENT_HCI_PACKET_SENT:
948         case HCI_EVENT_NUMBER_OF_COMPLETED_PACKETS:
949             l2cap_run();    // try sending signaling packets first
950             l2cap_notify_channel_can_send();
951             break;
952 
953         // HCI Connection Timeouts
954         case L2CAP_EVENT_TIMEOUT_CHECK:
955             handle = little_endian_read_16(packet, 2);
956             if (gap_get_connection_type(handle) != GAP_CONNECTION_ACL) break;
957             if (hci_authentication_active_for_handle(handle)) break;
958             hci_con_used = 0;
959             btstack_linked_list_iterator_init(&it, &l2cap_channels);
960             while (btstack_linked_list_iterator_has_next(&it)){
961                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
962                 if (channel->handle != handle) continue;
963                 hci_con_used = 1;
964                 break;
965             }
966             if (hci_con_used) break;
967             if (!hci_can_send_command_packet_now()) break;
968             hci_send_cmd(&hci_disconnect, handle, 0x13); // remote closed connection
969             break;
970 
971         case HCI_EVENT_READ_REMOTE_SUPPORTED_FEATURES_COMPLETE:
972             handle = little_endian_read_16(packet, 3);
973             btstack_linked_list_iterator_init(&it, &l2cap_channels);
974             while (btstack_linked_list_iterator_has_next(&it)){
975                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
976                 if (channel->handle != handle) continue;
977                 l2cap_handle_remote_supported_features_received(channel);
978                 break;
979             }
980             break;
981 
982         case GAP_EVENT_SECURITY_LEVEL:
983             handle = little_endian_read_16(packet, 2);
984             log_info("l2cap - security level update");
985             btstack_linked_list_iterator_init(&it, &l2cap_channels);
986             while (btstack_linked_list_iterator_has_next(&it)){
987                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
988                 if (channel->handle != handle) continue;
989 
990                 log_info("l2cap - state %u", channel->state);
991 
992                 gap_security_level_t actual_level = (gap_security_level_t) packet[4];
993                 gap_security_level_t required_level = channel->required_security_level;
994 
995                 switch (channel->state){
996                     case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
997                         if (actual_level >= required_level){
998                             channel->state = L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT;
999                             l2cap_emit_connection_request(channel);
1000                         } else {
1001                             channel->reason = 0x0003; // security block
1002                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
1003                         }
1004                         break;
1005 
1006                     case L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE:
1007                         if (actual_level >= required_level){
1008                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
1009                         } else {
1010                             // disconnnect, authentication not good enough
1011                             hci_disconnect_security_block(handle);
1012                         }
1013                         break;
1014 
1015                     default:
1016                         break;
1017                 }
1018             }
1019             break;
1020 
1021         default:
1022             break;
1023     }
1024 
1025     l2cap_run();
1026 }
1027 
1028 static void l2cap_handle_disconnect_request(l2cap_channel_t *channel, uint16_t identifier){
1029     channel->remote_sig_id = identifier;
1030     channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE;
1031     l2cap_run();
1032 }
1033 
1034 static void l2cap_register_signaling_response(hci_con_handle_t handle, uint8_t code, uint8_t sig_id, uint16_t data){
1035     // Vol 3, Part A, 4.3: "The DCID and SCID fields shall be ignored when the result field indi- cates the connection was refused."
1036     if (signaling_responses_pending < NR_PENDING_SIGNALING_RESPONSES) {
1037         signaling_responses[signaling_responses_pending].handle = handle;
1038         signaling_responses[signaling_responses_pending].code = code;
1039         signaling_responses[signaling_responses_pending].sig_id = sig_id;
1040         signaling_responses[signaling_responses_pending].data = data;
1041         signaling_responses_pending++;
1042         l2cap_run();
1043     }
1044 }
1045 
1046 static void l2cap_handle_connection_request(hci_con_handle_t handle, uint8_t sig_id, uint16_t psm, uint16_t source_cid){
1047 
1048     // log_info("l2cap_handle_connection_request for handle %u, psm %u cid 0x%02x", handle, psm, source_cid);
1049     l2cap_service_t *service = l2cap_get_service(psm);
1050     if (!service) {
1051         // 0x0002 PSM not supported
1052         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0002);
1053         return;
1054     }
1055 
1056     hci_connection_t * hci_connection = hci_connection_for_handle( handle );
1057     if (!hci_connection) {
1058         //
1059         log_error("no hci_connection for handle %u", handle);
1060         return;
1061     }
1062 
1063     // alloc structure
1064     // log_info("l2cap_handle_connection_request register channel");
1065     l2cap_channel_t * channel = btstack_memory_l2cap_channel_get();
1066     if (!channel){
1067         // 0x0004 No resources available
1068         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0004);
1069         return;
1070     }
1071     // Init memory (make valgrind happy)
1072     memset(channel, 0, sizeof(l2cap_channel_t));
1073     // fill in
1074     BD_ADDR_COPY(channel->address, hci_connection->address);
1075     channel->psm = psm;
1076     channel->handle = handle;
1077     channel->packet_handler = service->packet_handler;
1078     channel->local_cid  = l2cap_next_local_cid();
1079     channel->remote_cid = source_cid;
1080     channel->local_mtu  = service->mtu;
1081     channel->remote_mtu = L2CAP_DEFAULT_MTU;
1082     channel->remote_sig_id = sig_id;
1083     channel->required_security_level = service->required_security_level;
1084 
1085     // limit local mtu to max acl packet length - l2cap header
1086     if (channel->local_mtu > l2cap_max_mtu()) {
1087         channel->local_mtu = l2cap_max_mtu();
1088     }
1089 
1090     // set initial state
1091     channel->state =     L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE;
1092     channel->state_var = L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND;
1093 
1094     // add to connections list
1095     btstack_linked_list_add(&l2cap_channels, (btstack_linked_item_t *) channel);
1096 
1097     // assert security requirements
1098     gap_request_security_level(handle, channel->required_security_level);
1099 }
1100 
1101 void l2cap_accept_connection(uint16_t local_cid){
1102     log_info("L2CAP_ACCEPT_CONNECTION local_cid 0x%x", local_cid);
1103     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
1104     if (!channel) {
1105         log_error("l2cap_accept_connection called but local_cid 0x%x not found", local_cid);
1106         return;
1107     }
1108 
1109     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT;
1110 
1111     // process
1112     l2cap_run();
1113 }
1114 
1115 void l2cap_decline_connection(uint16_t local_cid, uint8_t reason){
1116     log_info("L2CAP_DECLINE_CONNECTION local_cid 0x%x, reason %x", local_cid, reason);
1117     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid( local_cid);
1118     if (!channel) {
1119         log_error( "l2cap_decline_connection called but local_cid 0x%x not found", local_cid);
1120         return;
1121     }
1122     channel->state  = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
1123     channel->reason = reason;
1124     l2cap_run();
1125 }
1126 
1127 static void l2cap_signaling_handle_configure_request(l2cap_channel_t *channel, uint8_t *command){
1128 
1129     channel->remote_sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1130 
1131     uint16_t flags = little_endian_read_16(command, 6);
1132     if (flags & 1) {
1133         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
1134     }
1135 
1136     // accept the other's configuration options
1137     uint16_t end_pos = 4 + little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1138     uint16_t pos     = 8;
1139     while (pos < end_pos){
1140         uint8_t option_hint = command[pos] >> 7;
1141         uint8_t option_type = command[pos] & 0x7f;
1142         log_info("l2cap cid %u, hint %u, type %u", channel->local_cid, option_hint, option_type);
1143         pos++;
1144         uint8_t length = command[pos++];
1145         // MTU { type(8): 1, len(8):2, MTU(16) }
1146         if (option_type == 1 && length == 2){
1147             channel->remote_mtu = little_endian_read_16(command, pos);
1148             // log_info("l2cap cid 0x%02x, remote mtu %u", channel->local_cid, channel->remote_mtu);
1149             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
1150         }
1151         // Flush timeout { type(8):2, len(8): 2, Flush Timeout(16)}
1152         if (option_type == 2 && length == 2){
1153             channel->flush_timeout = little_endian_read_16(command, pos);
1154         }
1155         // check for unknown options
1156         if (option_hint == 0 && (option_type == 0 || option_type >= 0x07)){
1157             log_info("l2cap cid %u, unknown options", channel->local_cid);
1158             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID);
1159         }
1160         pos += length;
1161     }
1162 }
1163 
1164 static int l2cap_channel_ready_for_open(l2cap_channel_t *channel){
1165     // log_info("l2cap_channel_ready_for_open 0x%02x", channel->state_var);
1166     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP) == 0) return 0;
1167     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP) == 0) return 0;
1168     // addition check that fixes re-entrance issue causing l2cap event channel opened twice
1169     if (channel->state == L2CAP_STATE_OPEN) return 0;
1170     return 1;
1171 }
1172 
1173 
1174 static void l2cap_signaling_handler_channel(l2cap_channel_t *channel, uint8_t *command){
1175 
1176     uint8_t  code       = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1177     uint8_t  identifier = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1178     uint16_t result = 0;
1179 
1180     log_info("L2CAP signaling handler code %u, state %u", code, channel->state);
1181 
1182     // handle DISCONNECT REQUESTS seperately
1183     if (code == DISCONNECTION_REQUEST){
1184         switch (channel->state){
1185             case L2CAP_STATE_CONFIG:
1186             case L2CAP_STATE_OPEN:
1187             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
1188             case L2CAP_STATE_WAIT_DISCONNECT:
1189                 l2cap_handle_disconnect_request(channel, identifier);
1190                 break;
1191 
1192             default:
1193                 // ignore in other states
1194                 break;
1195         }
1196         return;
1197     }
1198 
1199     // @STATEMACHINE(l2cap)
1200     switch (channel->state) {
1201 
1202         case L2CAP_STATE_WAIT_CONNECT_RSP:
1203             switch (code){
1204                 case CONNECTION_RESPONSE:
1205                     l2cap_stop_rtx(channel);
1206                     result = little_endian_read_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1207                     switch (result) {
1208                         case 0:
1209                             // successful connection
1210                             channel->remote_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1211                             channel->state = L2CAP_STATE_CONFIG;
1212                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1213                             break;
1214                         case 1:
1215                             // connection pending. get some coffee, but start the ERTX
1216                             l2cap_start_ertx(channel);
1217                             break;
1218                         default:
1219                             // channel closed
1220                             channel->state = L2CAP_STATE_CLOSED;
1221                             // map l2cap connection response result to BTstack status enumeration
1222                             l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result);
1223 
1224                             // drop link key if security block
1225                             if (L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result == L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_SECURITY){
1226                                 hci_drop_link_key_for_bd_addr(channel->address);
1227                             }
1228 
1229                             // discard channel
1230                             btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
1231                             btstack_memory_l2cap_channel_free(channel);
1232                             break;
1233                     }
1234                     break;
1235 
1236                 default:
1237                     //@TODO: implement other signaling packets
1238                     break;
1239             }
1240             break;
1241 
1242         case L2CAP_STATE_CONFIG:
1243             result = little_endian_read_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1244             switch (code) {
1245                 case CONFIGURE_REQUEST:
1246                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
1247                     l2cap_signaling_handle_configure_request(channel, command);
1248                     if (!(channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT)){
1249                         // only done if continuation not set
1250                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_REQ);
1251                     }
1252                     break;
1253                 case CONFIGURE_RESPONSE:
1254                     l2cap_stop_rtx(channel);
1255                     switch (result){
1256                         case 0: // success
1257                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP);
1258                             break;
1259                         case 4: // pending
1260                             l2cap_start_ertx(channel);
1261                             break;
1262                         default:
1263                             // retry on negative result
1264                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1265                             break;
1266                     }
1267                     break;
1268                 default:
1269                     break;
1270             }
1271             if (l2cap_channel_ready_for_open(channel)){
1272                 // for open:
1273                 channel->state = L2CAP_STATE_OPEN;
1274                 l2cap_emit_channel_opened(channel, 0);
1275             }
1276             break;
1277 
1278         case L2CAP_STATE_WAIT_DISCONNECT:
1279             switch (code) {
1280                 case DISCONNECTION_RESPONSE:
1281                     l2cap_finialize_channel_close(channel);
1282                     break;
1283                 default:
1284                     //@TODO: implement other signaling packets
1285                     break;
1286             }
1287             break;
1288 
1289         case L2CAP_STATE_CLOSED:
1290             // @TODO handle incoming requests
1291             break;
1292 
1293         case L2CAP_STATE_OPEN:
1294             //@TODO: implement other signaling packets, e.g. re-configure
1295             break;
1296         default:
1297             break;
1298     }
1299     // log_info("new state %u", channel->state);
1300 }
1301 
1302 
1303 static void l2cap_signaling_handler_dispatch( hci_con_handle_t handle, uint8_t * command){
1304 
1305     // get code, signalind identifier and command len
1306     uint8_t code   = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1307     uint8_t sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1308 
1309     // not for a particular channel, and not CONNECTION_REQUEST, ECHO_[REQUEST|RESPONSE], INFORMATION_REQUEST
1310     if (code < 1 || code == ECHO_RESPONSE || code > INFORMATION_REQUEST){
1311         l2cap_register_signaling_response(handle, COMMAND_REJECT, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1312         return;
1313     }
1314 
1315     // general commands without an assigned channel
1316     switch(code) {
1317 
1318         case CONNECTION_REQUEST: {
1319             uint16_t psm =        little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1320             uint16_t source_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+2);
1321             l2cap_handle_connection_request(handle, sig_id, psm, source_cid);
1322             return;
1323         }
1324 
1325         case ECHO_REQUEST:
1326             l2cap_register_signaling_response(handle, code, sig_id, 0);
1327             return;
1328 
1329         case INFORMATION_REQUEST: {
1330             uint16_t infoType = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1331             l2cap_register_signaling_response(handle, code, sig_id, infoType);
1332             return;
1333         }
1334 
1335         default:
1336             break;
1337     }
1338 
1339 
1340     // Get potential destination CID
1341     uint16_t dest_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1342 
1343     // Find channel for this sig_id and connection handle
1344     btstack_linked_list_iterator_t it;
1345     btstack_linked_list_iterator_init(&it, &l2cap_channels);
1346     while (btstack_linked_list_iterator_has_next(&it)){
1347         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
1348         if (channel->handle != handle) continue;
1349         if (code & 1) {
1350             // match odd commands (responses) by previous signaling identifier
1351             if (channel->local_sig_id == sig_id) {
1352                 l2cap_signaling_handler_channel(channel, command);
1353                 break;
1354             }
1355         } else {
1356             // match even commands (requests) by local channel id
1357             if (channel->local_cid == dest_cid) {
1358                 l2cap_signaling_handler_channel(channel, command);
1359                 break;
1360             }
1361         }
1362     }
1363 }
1364 
1365 static void l2cap_acl_handler(uint8_t packet_type, uint8_t *packet, uint16_t size ){
1366 
1367     // Get Channel ID
1368     uint16_t channel_id = READ_L2CAP_CHANNEL_ID(packet);
1369     hci_con_handle_t handle = READ_ACL_CONNECTION_HANDLE(packet);
1370 
1371     switch (channel_id) {
1372 
1373         case L2CAP_CID_SIGNALING: {
1374 
1375             uint16_t command_offset = 8;
1376             while (command_offset < size) {
1377 
1378                 // handle signaling commands
1379                 l2cap_signaling_handler_dispatch(handle, &packet[command_offset]);
1380 
1381                 // increment command_offset
1382                 command_offset += L2CAP_SIGNALING_COMMAND_DATA_OFFSET + little_endian_read_16(packet, command_offset + L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1383             }
1384             break;
1385         }
1386 
1387         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
1388             if (fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL].callback) {
1389                 (*fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL].callback)(ATT_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1390             }
1391             break;
1392 
1393         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
1394             if (fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL].callback) {
1395                 (*fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL].callback)(SM_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1396             }
1397             break;
1398 
1399         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
1400             if (fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL].callback) {
1401                 (*fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL].callback)(UCD_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1402             }
1403             break;
1404 
1405         case L2CAP_CID_SIGNALING_LE: {
1406             switch (packet[8]){
1407                 case CONNECTION_PARAMETER_UPDATE_RESPONSE: {
1408                     uint16_t result = little_endian_read_16(packet, 12);
1409                     l2cap_emit_connection_parameter_update_response(handle, result);
1410                     break;
1411                 }
1412                 case CONNECTION_PARAMETER_UPDATE_REQUEST: {
1413                     uint8_t event[10];
1414                     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_REQUEST;
1415                     event[1] = 8;
1416                     memcpy(&event[2], &packet[12], 8);
1417 
1418                     hci_connection_t * connection = hci_connection_for_handle(handle);
1419                     if (connection){
1420                         if (connection->role != HCI_ROLE_MASTER){
1421                             // reject command without notifying upper layer when not in master role
1422                             uint8_t sig_id = packet[COMPLETE_L2CAP_HEADER + 1];
1423                             l2cap_register_signaling_response(handle, COMMAND_REJECT_LE, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1424                             break;
1425                         }
1426                         int update_parameter = 1;
1427                         le_connection_parameter_range_t existing_range;
1428                         gap_le_get_connection_parameter_range(existing_range);
1429                         uint16_t le_conn_interval_min = little_endian_read_16(packet,12);
1430                         uint16_t le_conn_interval_max = little_endian_read_16(packet,14);
1431                         uint16_t le_conn_latency = little_endian_read_16(packet,16);
1432                         uint16_t le_supervision_timeout = little_endian_read_16(packet,18);
1433 
1434                         if (le_conn_interval_min < existing_range.le_conn_interval_min) update_parameter = 0;
1435                         if (le_conn_interval_max > existing_range.le_conn_interval_max) update_parameter = 0;
1436 
1437                         if (le_conn_latency < existing_range.le_conn_latency_min) update_parameter = 0;
1438                         if (le_conn_latency > existing_range.le_conn_latency_max) update_parameter = 0;
1439 
1440                         if (le_supervision_timeout < existing_range.le_supervision_timeout_min) update_parameter = 0;
1441                         if (le_supervision_timeout > existing_range.le_supervision_timeout_max) update_parameter = 0;
1442 
1443                         if (update_parameter){
1444                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_SEND_RESPONSE;
1445                             connection->le_conn_interval_min = le_conn_interval_min;
1446                             connection->le_conn_interval_max = le_conn_interval_max;
1447                             connection->le_conn_latency = le_conn_latency;
1448                             connection->le_supervision_timeout = le_supervision_timeout;
1449                         } else {
1450                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_DENY;
1451                         }
1452                         connection->le_con_param_update_identifier = packet[COMPLETE_L2CAP_HEADER + 1];
1453                     }
1454 
1455                     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
1456                     if (!l2cap_event_packet_handler) break;
1457                     (*l2cap_event_packet_handler)( HCI_EVENT_PACKET, 0, event, sizeof(event));
1458                     break;
1459                 }
1460                 default: {
1461                     uint8_t sig_id = packet[COMPLETE_L2CAP_HEADER + 1];
1462                     l2cap_register_signaling_response(handle, COMMAND_REJECT_LE, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1463                     break;
1464                 }
1465             }
1466             break;
1467         }
1468 
1469         default: {
1470             // Find channel for this channel_id and connection handle
1471             l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(channel_id);
1472             if (channel) {
1473                 l2cap_dispatch_to_channel(channel, L2CAP_DATA_PACKET, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1474             }
1475             break;
1476         }
1477     }
1478 
1479     l2cap_run();
1480 }
1481 
1482 // finalize closed channel - l2cap_handle_disconnect_request & DISCONNECTION_RESPONSE
1483 void l2cap_finialize_channel_close(l2cap_channel_t *channel){
1484     channel->state = L2CAP_STATE_CLOSED;
1485     l2cap_emit_channel_closed(channel);
1486     // discard channel
1487     l2cap_stop_rtx(channel);
1488     btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
1489     btstack_memory_l2cap_channel_free(channel);
1490 }
1491 
1492 static l2cap_service_t * l2cap_get_service_internal(btstack_linked_list_t * services, uint16_t psm){
1493     btstack_linked_list_iterator_t it;
1494     btstack_linked_list_iterator_init(&it, services);
1495     while (btstack_linked_list_iterator_has_next(&it)){
1496         l2cap_service_t * service = (l2cap_service_t *) btstack_linked_list_iterator_next(&it);
1497         if ( service->psm == psm){
1498             return service;
1499         };
1500     }
1501     return NULL;
1502 }
1503 
1504 static inline l2cap_service_t * l2cap_get_service(uint16_t psm){
1505     return l2cap_get_service_internal(&l2cap_services, psm);
1506 }
1507 
1508 
1509 uint8_t l2cap_register_service(btstack_packet_handler_t service_packet_handler, uint16_t psm, uint16_t mtu, gap_security_level_t security_level){
1510 
1511     log_info("L2CAP_REGISTER_SERVICE psm 0x%x mtu %u", psm, mtu);
1512 
1513     // check for alread registered psm
1514     // TODO: emit error event
1515     l2cap_service_t *service = l2cap_get_service(psm);
1516     if (service) {
1517         log_error("l2cap_register_service: PSM %u already registered", psm);
1518         return L2CAP_SERVICE_ALREADY_REGISTERED;
1519     }
1520 
1521     // alloc structure
1522     // TODO: emit error event
1523     service = btstack_memory_l2cap_service_get();
1524     if (!service) {
1525         log_error("l2cap_register_service: no memory for l2cap_service_t");
1526         return BTSTACK_MEMORY_ALLOC_FAILED;
1527     }
1528 
1529     // fill in
1530     service->psm = psm;
1531     service->mtu = mtu;
1532     service->packet_handler = service_packet_handler;
1533     service->required_security_level = security_level;
1534 
1535     // add to services list
1536     btstack_linked_list_add(&l2cap_services, (btstack_linked_item_t *) service);
1537 
1538     // enable page scan
1539     hci_connectable_control(1);
1540 
1541     return 0;
1542 }
1543 
1544 void l2cap_unregister_service(uint16_t psm){
1545 
1546     log_info("L2CAP_UNREGISTER_SERVICE psm 0x%x", psm);
1547 
1548     l2cap_service_t *service = l2cap_get_service(psm);
1549     if (!service) return;
1550     btstack_linked_list_remove(&l2cap_services, (btstack_linked_item_t *) service);
1551     btstack_memory_l2cap_service_free(service);
1552 
1553     // disable page scan when no services registered
1554     if (!btstack_linked_list_empty(&l2cap_services)) return;
1555     hci_connectable_control(0);
1556 }
1557 
1558 // Bluetooth 4.0 - allows to register handler for Attribute Protocol and Security Manager Protocol
1559 void l2cap_register_fixed_channel(btstack_packet_handler_t the_packet_handler, uint16_t channel_id) {
1560     int index = l2cap_fixed_channel_table_index_for_channel_id(channel_id);
1561     if (index < 0) return;
1562     fixed_channels[index].callback = the_packet_handler;
1563 }
1564 
1565 #ifdef ENABLE_BLE
1566 
1567 
1568 #if 0
1569 static inline l2cap_service_t * l2cap_le_get_service(uint16_t psm){
1570     return l2cap_get_service_internal(&l2cap_le_services, psm);
1571 }
1572 /**
1573  * @brief Regster L2CAP LE Credit Based Flow Control Mode service
1574  * @param
1575  */
1576 void l2cap_le_register_service(btstack_packet_handler_t packet_handler, uint16_t psm,
1577     uint16_t mtu, uint16_t mps, uint16_t initial_credits, gap_security_level_t security_level){
1578 
1579     log_info("L2CAP_LE_REGISTER_SERVICE psm 0x%x mtu %u connection %p", psm, mtu, connection);
1580 
1581     // check for alread registered psm
1582     // TODO: emit error event
1583     l2cap_service_t *service = l2cap_le_get_service(psm);
1584     if (service) {
1585         log_error("l2cap_le_register_service_internal: PSM %u already registered", psm);
1586         l2cap_emit_service_registered(connection, L2CAP_SERVICE_ALREADY_REGISTERED, psm);
1587         return;
1588     }
1589 
1590     // alloc structure
1591     // TODO: emit error event
1592     service = btstack_memory_l2cap_service_get();
1593     if (!service) {
1594         log_error("l2cap_register_service_internal: no memory for l2cap_service_t");
1595         l2cap_emit_service_registered(connection, BTSTACK_MEMORY_ALLOC_FAILED, psm);
1596         return;
1597     }
1598 
1599     // fill in
1600     service->psm = psm;
1601     service->mtu = mtu;
1602     service->mps = mps;
1603     service->packet_handler = packet_handler;
1604     service->required_security_level = security_level;
1605 
1606     // add to services list
1607     btstack_linked_list_add(&l2cap_le_services, (btstack_linked_item_t *) service);
1608 
1609     // done
1610     l2cap_emit_service_registered(connection, 0, psm);
1611 }
1612 
1613 void l2cap_le_unregister_service(uint16_t psm) {
1614 
1615     log_info("L2CAP_LE_UNREGISTER_SERVICE psm 0x%x", psm);
1616 
1617     l2cap_service_t *service = l2cap_le_get_service(psm);
1618     if (!service) return;
1619     btstack_linked_list_remove(&l2cap_le_services, (btstack_linked_item_t *) service);
1620     btstack_memory_l2cap_service_free(service);
1621 }
1622 #endif
1623 #endif
1624