xref: /btstack/src/l2cap.c (revision 0e2df43f5cbae3fc71139523458b98f30307d21b)
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.
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_event.h"
51 #include "btstack_memory.h"
52 
53 #include <stdarg.h>
54 #include <string.h>
55 
56 #include <stdio.h>
57 
58 // nr of buffered acl packets in outgoing queue to get max performance
59 #define NR_BUFFERED_ACL_PACKETS 3
60 
61 // used to cache l2cap rejects, echo, and informational requests
62 #define NR_PENDING_SIGNALING_RESPONSES 3
63 
64 // offsets for L2CAP SIGNALING COMMANDS
65 #define L2CAP_SIGNALING_COMMAND_CODE_OFFSET   0
66 #define L2CAP_SIGNALING_COMMAND_SIGID_OFFSET  1
67 #define L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET 2
68 #define L2CAP_SIGNALING_COMMAND_DATA_OFFSET   4
69 
70 // internal table
71 #define L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL 0
72 #define L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL  1
73 #define L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL 2
74 #define L2CAP_FIXED_CHANNEL_TABLE_SIZE (L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL+1)
75 
76 // prototypes
77 static void l2cap_finialize_channel_close(l2cap_channel_t *channel);
78 static inline l2cap_service_t * l2cap_get_service(uint16_t psm);
79 static void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status);
80 static void l2cap_emit_can_send_now(btstack_packet_handler_t packet_handler, uint16_t channel);
81 static void l2cap_emit_channel_closed(l2cap_channel_t *channel);
82 static void l2cap_emit_connection_request(l2cap_channel_t *channel);
83 static int  l2cap_channel_ready_for_open(l2cap_channel_t *channel);
84 static void l2cap_hci_event_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
85 static void l2cap_acl_handler(uint8_t packet_type, uint8_t *packet, uint16_t size );
86 
87 typedef struct l2cap_fixed_channel {
88     btstack_packet_handler_t callback;
89     uint8_t waiting_for_can_send_now;
90 } l2cap_fixed_channel_t;
91 
92 static btstack_linked_list_t l2cap_channels;
93 static btstack_linked_list_t l2cap_services;
94 static btstack_linked_list_t l2cap_le_channels;
95 static btstack_linked_list_t l2cap_le_services;
96 
97 // used to cache l2cap rejects, echo, and informational requests
98 static l2cap_signaling_response_t signaling_responses[NR_PENDING_SIGNALING_RESPONSES];
99 static int signaling_responses_pending;
100 
101 static uint8_t require_security_level2_for_outgoing_sdp;
102 
103 static btstack_packet_callback_registration_t hci_event_callback_registration;
104 
105 static btstack_packet_handler_t l2cap_event_packet_handler;
106 static l2cap_fixed_channel_t fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_SIZE];
107 
108 static uint16_t l2cap_fixed_channel_table_channel_id_for_index(int index){
109     switch (index){
110         case L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL:
111             return L2CAP_CID_ATTRIBUTE_PROTOCOL;
112         case L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL:
113             return L2CAP_CID_SECURITY_MANAGER_PROTOCOL;
114         case L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL:
115             return L2CAP_CID_CONNECTIONLESS_CHANNEL;
116         default:
117             return 0;
118     }
119 }
120 static int l2cap_fixed_channel_table_index_for_channel_id(uint16_t channel_id){
121     switch (channel_id){
122         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
123             return L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL;
124         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
125             return  L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL;
126         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
127             return  L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL;
128         default:
129             return -1;
130         }
131 }
132 
133 static int l2cap_fixed_channel_table_index_is_le(int index){
134     if (index == L2CAP_CID_CONNECTIONLESS_CHANNEL) return 0;
135     return 1;
136 }
137 
138 void l2cap_init(void){
139     signaling_responses_pending = 0;
140 
141     l2cap_channels = NULL;
142     l2cap_services = NULL;
143     l2cap_le_services = NULL;
144     l2cap_le_channels = NULL;
145 
146     l2cap_event_packet_handler = NULL;
147     memset(fixed_channels, 0, sizeof(fixed_channels));
148 
149     require_security_level2_for_outgoing_sdp = 0;
150 
151     //
152     // register callback with HCI
153     //
154     hci_event_callback_registration.callback = &l2cap_hci_event_handler;
155     hci_add_event_handler(&hci_event_callback_registration);
156 
157     hci_register_acl_packet_handler(&l2cap_acl_handler);
158 
159     gap_connectable_control(0); // no services yet
160 }
161 
162 void l2cap_register_packet_handler(void (*handler)(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size)){
163     l2cap_event_packet_handler = handler;
164 }
165 
166 static void l2cap_dispatch_to_channel(l2cap_channel_t *channel, uint8_t type, uint8_t * data, uint16_t size){
167     (* (channel->packet_handler))(type, channel->local_cid, data, size);
168 }
169 
170 void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status) {
171     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",
172              status, bd_addr_to_str(channel->address), channel->con_handle, channel->psm,
173              channel->local_cid, channel->remote_cid, channel->local_mtu, channel->remote_mtu, channel->flush_timeout);
174     uint8_t event[23];
175     event[0] = L2CAP_EVENT_CHANNEL_OPENED;
176     event[1] = sizeof(event) - 2;
177     event[2] = status;
178     reverse_bd_addr(channel->address, &event[3]);
179     little_endian_store_16(event,  9, channel->con_handle);
180     little_endian_store_16(event, 11, channel->psm);
181     little_endian_store_16(event, 13, channel->local_cid);
182     little_endian_store_16(event, 15, channel->remote_cid);
183     little_endian_store_16(event, 17, channel->local_mtu);
184     little_endian_store_16(event, 19, channel->remote_mtu);
185     little_endian_store_16(event, 21, channel->flush_timeout);
186     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
187     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
188 
189     // if channel opened successfully, also send can send now if possible
190     if (status) return;
191     if (hci_can_send_acl_packet_now(channel->con_handle)){
192         l2cap_emit_can_send_now(channel->packet_handler, channel->local_cid);
193     } else {
194         channel->waiting_for_can_send_now = 1;
195     }
196 }
197 
198 void l2cap_emit_channel_closed(l2cap_channel_t *channel) {
199     log_info("L2CAP_EVENT_CHANNEL_CLOSED local_cid 0x%x", channel->local_cid);
200     uint8_t event[4];
201     event[0] = L2CAP_EVENT_CHANNEL_CLOSED;
202     event[1] = sizeof(event) - 2;
203     little_endian_store_16(event, 2, channel->local_cid);
204     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
205     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
206 }
207 
208 void l2cap_emit_connection_request(l2cap_channel_t *channel) {
209     log_info("L2CAP_EVENT_INCOMING_CONNECTION addr %s handle 0x%x psm 0x%x local_cid 0x%x remote_cid 0x%x",
210              bd_addr_to_str(channel->address), channel->con_handle,  channel->psm, channel->local_cid, channel->remote_cid);
211     uint8_t event[16];
212     event[0] = L2CAP_EVENT_INCOMING_CONNECTION;
213     event[1] = sizeof(event) - 2;
214     reverse_bd_addr(channel->address, &event[2]);
215     little_endian_store_16(event,  8, channel->con_handle);
216     little_endian_store_16(event, 10, channel->psm);
217     little_endian_store_16(event, 12, channel->local_cid);
218     little_endian_store_16(event, 14, channel->remote_cid);
219     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
220     l2cap_dispatch_to_channel(channel, HCI_EVENT_PACKET, event, sizeof(event));
221 }
222 
223 static void l2cap_emit_can_send_now(btstack_packet_handler_t packet_handler, uint16_t channel) {
224     log_info("L2CAP_EVENT_CHANNEL_CAN_SEND_NOW local_cid 0x%x", channel);
225     uint8_t event[4];
226     event[0] = L2CAP_EVENT_CAN_SEND_NOW;
227     event[1] = sizeof(event) - 2;
228     little_endian_store_16(event, 2, channel);
229     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
230     packet_handler(HCI_EVENT_PACKET, channel, event, sizeof(event));
231 }
232 
233 static void l2cap_emit_connection_parameter_update_response(hci_con_handle_t con_handle, uint16_t result){
234     uint8_t event[6];
235     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_RESPONSE;
236     event[1] = 4;
237     little_endian_store_16(event, 2, con_handle);
238     little_endian_store_16(event, 4, result);
239     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
240     if (!l2cap_event_packet_handler) return;
241     (*l2cap_event_packet_handler)(HCI_EVENT_PACKET, 0, event, sizeof(event));
242 }
243 
244 static l2cap_channel_t * l2cap_get_channel_for_local_cid(uint16_t local_cid){
245     btstack_linked_list_iterator_t it;
246     btstack_linked_list_iterator_init(&it, &l2cap_channels);
247     while (btstack_linked_list_iterator_has_next(&it)){
248         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
249         if ( channel->local_cid == local_cid) {
250             return channel;
251         }
252     }
253     return NULL;
254 }
255 
256 int  l2cap_can_send_packet_now(uint16_t local_cid){
257     l2cap_channel_t *channel = l2cap_get_channel_for_local_cid(local_cid);
258     if (!channel) return 0;
259     int can_send = hci_can_send_acl_packet_now(channel->con_handle);
260     if (!can_send){
261         channel->waiting_for_can_send_now = 1;
262     }
263     return can_send;
264 }
265 
266 int  l2cap_can_send_prepared_packet_now(uint16_t local_cid){
267     l2cap_channel_t *channel = l2cap_get_channel_for_local_cid(local_cid);
268     if (!channel) return 0;
269     int can_send = hci_can_send_prepared_acl_packet_now(channel->con_handle);
270     if (!can_send){
271         channel->waiting_for_can_send_now = 1;
272     }
273     return can_send;
274 }
275 
276 int  l2cap_can_send_fixed_channel_packet_now(hci_con_handle_t con_handle, uint16_t channel_id){
277     int can_send = hci_can_send_acl_packet_now(con_handle);
278     if (!can_send){
279         int index = l2cap_fixed_channel_table_index_for_channel_id(channel_id);
280         if (index >= 0){
281             fixed_channels[index].waiting_for_can_send_now = 1;
282         }
283     }
284     return can_send;
285 }
286 
287 uint16_t l2cap_get_remote_mtu_for_local_cid(uint16_t local_cid){
288     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
289     if (channel) {
290         return channel->remote_mtu;
291     }
292     return 0;
293 }
294 
295 static l2cap_channel_t * l2cap_channel_for_rtx_timer(btstack_timer_source_t * ts){
296     btstack_linked_list_iterator_t it;
297     btstack_linked_list_iterator_init(&it, &l2cap_channels);
298     while (btstack_linked_list_iterator_has_next(&it)){
299         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
300         if ( &channel->rtx == ts) {
301             return channel;
302         }
303     }
304     return NULL;
305 }
306 
307 static void l2cap_rtx_timeout(btstack_timer_source_t * ts){
308     l2cap_channel_t * channel = l2cap_channel_for_rtx_timer(ts);
309     if (!ts) return;
310 
311     log_info("l2cap_rtx_timeout for local cid 0x%02x", channel->local_cid);
312 
313     // "When terminating the channel, it is not necessary to send a L2CAP_DisconnectReq
314     //  and enter WAIT_DISCONNECT state. Channels can be transitioned directly to the CLOSED state."
315     // notify client
316     l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_RTX_TIMEOUT);
317 
318     // discard channel
319     // no need to stop timer here, it is removed from list during timer callback
320     btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
321     btstack_memory_l2cap_channel_free(channel);
322 }
323 
324 static void l2cap_stop_rtx(l2cap_channel_t * channel){
325     log_info("l2cap_stop_rtx for local cid 0x%02x", channel->local_cid);
326     btstack_run_loop_remove_timer(&channel->rtx);
327 }
328 
329 static void l2cap_start_rtx(l2cap_channel_t * channel){
330     l2cap_stop_rtx(channel);
331     log_info("l2cap_start_rtx for local cid 0x%02x", channel->local_cid);
332     btstack_run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
333     btstack_run_loop_set_timer(&channel->rtx, L2CAP_RTX_TIMEOUT_MS);
334     btstack_run_loop_add_timer(&channel->rtx);
335 }
336 
337 static void l2cap_start_ertx(l2cap_channel_t * channel){
338     log_info("l2cap_start_ertx for local cid 0x%02x", channel->local_cid);
339     l2cap_stop_rtx(channel);
340     btstack_run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
341     btstack_run_loop_set_timer(&channel->rtx, L2CAP_ERTX_TIMEOUT_MS);
342     btstack_run_loop_add_timer(&channel->rtx);
343 }
344 
345 void l2cap_require_security_level_2_for_outgoing_sdp(void){
346     require_security_level2_for_outgoing_sdp = 1;
347 }
348 
349 static int l2cap_security_level_0_allowed_for_PSM(uint16_t psm){
350     return (psm == PSM_SDP) && (!require_security_level2_for_outgoing_sdp);
351 }
352 
353 static int l2cap_send_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
354 
355     if (!hci_can_send_acl_packet_now(handle)){
356         log_info("l2cap_send_signaling_packet, cannot send");
357         return BTSTACK_ACL_BUFFERS_FULL;
358     }
359 
360     // log_info("l2cap_send_signaling_packet type %u", cmd);
361     hci_reserve_packet_buffer();
362     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
363     va_list argptr;
364     va_start(argptr, identifier);
365     uint16_t len = l2cap_create_signaling_classic(acl_buffer, handle, cmd, identifier, argptr);
366     va_end(argptr);
367     // log_info("l2cap_send_signaling_packet con %u!", handle);
368     return hci_send_acl_packet_buffer(len);
369 }
370 
371 #ifdef ENABLE_BLE
372 static int l2cap_send_le_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
373 
374     if (!hci_can_send_acl_packet_now(handle)){
375         log_info("l2cap_send_signaling_packet, cannot send");
376         return BTSTACK_ACL_BUFFERS_FULL;
377     }
378 
379     // log_info("l2cap_send_signaling_packet type %u", cmd);
380     hci_reserve_packet_buffer();
381     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
382     va_list argptr;
383     va_start(argptr, identifier);
384     uint16_t len = l2cap_create_signaling_le(acl_buffer, handle, cmd, identifier, argptr);
385     va_end(argptr);
386     // log_info("l2cap_send_signaling_packet con %u!", handle);
387     return hci_send_acl_packet_buffer(len);
388 }
389 #endif
390 
391 uint8_t *l2cap_get_outgoing_buffer(void){
392     return hci_get_outgoing_packet_buffer() + COMPLETE_L2CAP_HEADER; // 8 bytes
393 }
394 
395 int l2cap_reserve_packet_buffer(void){
396     return hci_reserve_packet_buffer();
397 }
398 
399 void l2cap_release_packet_buffer(void){
400     hci_release_packet_buffer();
401 }
402 
403 
404 int l2cap_send_prepared(uint16_t local_cid, uint16_t len){
405 
406     if (!hci_is_packet_buffer_reserved()){
407         log_error("l2cap_send_prepared called without reserving packet first");
408         return BTSTACK_ACL_BUFFERS_FULL;
409     }
410 
411     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
412     if (!channel) {
413         log_error("l2cap_send_prepared no channel for cid 0x%02x", local_cid);
414         return -1;   // TODO: define error
415     }
416 
417     if (!hci_can_send_prepared_acl_packet_now(channel->con_handle)){
418         log_info("l2cap_send_prepared cid 0x%02x, cannot send", local_cid);
419         return BTSTACK_ACL_BUFFERS_FULL;
420     }
421 
422     log_debug("l2cap_send_prepared cid 0x%02x, handle %u, 1 credit used", local_cid, channel->con_handle);
423 
424     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
425 
426     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
427 
428     // 0 - Connection handle : PB=pb : BC=00
429     little_endian_store_16(acl_buffer, 0, channel->con_handle | (pb << 12) | (0 << 14));
430     // 2 - ACL length
431     little_endian_store_16(acl_buffer, 2,  len + 4);
432     // 4 - L2CAP packet length
433     little_endian_store_16(acl_buffer, 4,  len + 0);
434     // 6 - L2CAP channel DEST
435     little_endian_store_16(acl_buffer, 6, channel->remote_cid);
436     // send
437     int err = hci_send_acl_packet_buffer(len+8);
438 
439     return err;
440 }
441 
442 int l2cap_send_prepared_connectionless(hci_con_handle_t con_handle, uint16_t cid, uint16_t len){
443 
444     if (!hci_is_packet_buffer_reserved()){
445         log_error("l2cap_send_prepared_connectionless called without reserving packet first");
446         return BTSTACK_ACL_BUFFERS_FULL;
447     }
448 
449     if (!hci_can_send_prepared_acl_packet_now(con_handle)){
450         log_info("l2cap_send_prepared_connectionless handle 0x%02x, cid 0x%02x, cannot send", con_handle, cid);
451         return BTSTACK_ACL_BUFFERS_FULL;
452     }
453 
454     log_debug("l2cap_send_prepared_connectionless handle %u, cid 0x%02x", con_handle, cid);
455 
456     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
457 
458     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
459 
460     // 0 - Connection handle : PB=pb : BC=00
461     little_endian_store_16(acl_buffer, 0, con_handle | (pb << 12) | (0 << 14));
462     // 2 - ACL length
463     little_endian_store_16(acl_buffer, 2,  len + 4);
464     // 4 - L2CAP packet length
465     little_endian_store_16(acl_buffer, 4,  len + 0);
466     // 6 - L2CAP channel DEST
467     little_endian_store_16(acl_buffer, 6, cid);
468     // send
469     int err = hci_send_acl_packet_buffer(len+8);
470 
471     return err;
472 }
473 
474 int l2cap_send(uint16_t local_cid, uint8_t *data, uint16_t len){
475 
476     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
477     if (!channel) {
478         log_error("l2cap_send no channel for cid 0x%02x", local_cid);
479         return -1;   // TODO: define error
480     }
481 
482     if (len > channel->remote_mtu){
483         log_error("l2cap_send cid 0x%02x, data length exceeds remote MTU.", local_cid);
484         return L2CAP_DATA_LEN_EXCEEDS_REMOTE_MTU;
485     }
486 
487     if (!hci_can_send_acl_packet_now(channel->con_handle)){
488         log_info("l2cap_send cid 0x%02x, cannot send", local_cid);
489         return BTSTACK_ACL_BUFFERS_FULL;
490     }
491 
492     hci_reserve_packet_buffer();
493     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
494 
495     memcpy(&acl_buffer[8], data, len);
496 
497     return l2cap_send_prepared(local_cid, len);
498 }
499 
500 int l2cap_send_connectionless(hci_con_handle_t con_handle, uint16_t cid, uint8_t *data, uint16_t len){
501 
502     if (!hci_can_send_acl_packet_now(con_handle)){
503         log_info("l2cap_send cid 0x%02x, cannot send", cid);
504         return BTSTACK_ACL_BUFFERS_FULL;
505     }
506 
507     hci_reserve_packet_buffer();
508     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
509 
510     memcpy(&acl_buffer[8], data, len);
511 
512     return l2cap_send_prepared_connectionless(con_handle, cid, len);
513 }
514 
515 int l2cap_send_echo_request(hci_con_handle_t con_handle, uint8_t *data, uint16_t len){
516     return l2cap_send_signaling_packet(con_handle, ECHO_REQUEST, 0x77, len, data);
517 }
518 
519 static inline void channelStateVarSetFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
520     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var | flag);
521 }
522 
523 static inline void channelStateVarClearFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
524     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var & ~flag);
525 }
526 
527 
528 
529 // MARK: L2CAP_RUN
530 // process outstanding signaling tasks
531 static void l2cap_run(void){
532 
533     // log_info("l2cap_run: entered");
534 
535     // check pending signaling responses
536     while (signaling_responses_pending){
537 
538         hci_con_handle_t handle = signaling_responses[0].handle;
539 
540         if (!hci_can_send_acl_packet_now(handle)) break;
541 
542         uint8_t  sig_id = signaling_responses[0].sig_id;
543         uint16_t infoType = signaling_responses[0].data;    // INFORMATION_REQUEST
544         uint16_t result   = signaling_responses[0].data;    // CONNECTION_REQUEST, COMMAND_REJECT
545         uint8_t  response_code = signaling_responses[0].code;
546 
547         // remove first item before sending (to avoid sending response mutliple times)
548         signaling_responses_pending--;
549         int i;
550         for (i=0; i < signaling_responses_pending; i++){
551             memcpy(&signaling_responses[i], &signaling_responses[i+1], sizeof(l2cap_signaling_response_t));
552         }
553 
554         switch (response_code){
555             case CONNECTION_REQUEST:
556                 l2cap_send_signaling_packet(handle, CONNECTION_RESPONSE, sig_id, 0, 0, result, 0);
557                 // also disconnect if result is 0x0003 - security blocked
558                 if (result == 0x0003){
559                     hci_disconnect_security_block(handle);
560                 }
561                 break;
562             case ECHO_REQUEST:
563                 l2cap_send_signaling_packet(handle, ECHO_RESPONSE, sig_id, 0, NULL);
564                 break;
565             case INFORMATION_REQUEST:
566                 switch (infoType){
567                     case 1: { // Connectionless MTU
568                         uint16_t connectionless_mtu = hci_max_acl_data_packet_length();
569                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(connectionless_mtu), &connectionless_mtu);
570                         break;
571                     }
572                     case 2: { // Extended Features Supported
573                         // extended features request supported, features: fixed channels, unicast connectionless data reception
574                         uint32_t features = 0x280;
575                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(features), &features);
576                         break;
577                     }
578                     case 3: { // Fixed Channels Supported
579                         uint8_t map[8];
580                         memset(map, 0, 8);
581                         map[0] = 0x01;  // L2CAP Signaling Channel (0x01) + Connectionless reception (0x02)
582                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(map), &map);
583                         break;
584                     }
585                     default:
586                         // all other types are not supported
587                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 1, 0, NULL);
588                         break;
589                 }
590                 break;
591             case COMMAND_REJECT:
592                 l2cap_send_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
593 #ifdef ENABLE_BLE
594             case COMMAND_REJECT_LE:
595                 l2cap_send_le_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
596                 break;
597 #endif
598             default:
599                 // should not happen
600                 break;
601         }
602     }
603 
604     uint8_t  config_options[4];
605     btstack_linked_list_iterator_t it;
606     btstack_linked_list_iterator_init(&it, &l2cap_channels);
607     while (btstack_linked_list_iterator_has_next(&it)){
608 
609         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
610         // log_info("l2cap_run: channel %p, state %u, var 0x%02x", channel, channel->state, channel->state_var);
611         switch (channel->state){
612 
613             case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
614             case L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT:
615                 if (!hci_can_send_acl_packet_now(channel->con_handle)) break;
616                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND) {
617                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND);
618                     l2cap_send_signaling_packet(channel->con_handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 1, 0);
619                 }
620                 break;
621 
622             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
623                 if (!hci_can_send_command_packet_now()) break;
624                 // send connection request - set state first
625                 channel->state = L2CAP_STATE_WAIT_CONNECTION_COMPLETE;
626                 // BD_ADDR, Packet_Type, Page_Scan_Repetition_Mode, Reserved, Clock_Offset, Allow_Role_Switch
627                 hci_send_cmd(&hci_create_connection, channel->address, hci_usable_acl_packet_types(), 0, 0, 0, 1);
628                 break;
629 
630             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE:
631                 if (!hci_can_send_acl_packet_now(channel->con_handle)) break;
632                 channel->state = L2CAP_STATE_INVALID;
633                 l2cap_send_signaling_packet(channel->con_handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, channel->reason, 0);
634                 // discard channel - l2cap_finialize_channel_close without sending l2cap close event
635                 l2cap_stop_rtx(channel);
636                 btstack_linked_list_iterator_remove(&it);
637                 btstack_memory_l2cap_channel_free(channel);
638                 break;
639 
640             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT:
641                 if (!hci_can_send_acl_packet_now(channel->con_handle)) break;
642                 channel->state = L2CAP_STATE_CONFIG;
643                 channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
644                 l2cap_send_signaling_packet(channel->con_handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 0, 0);
645                 break;
646 
647             case L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST:
648                 if (!hci_can_send_acl_packet_now(channel->con_handle)) break;
649                 // success, start l2cap handshake
650                 channel->local_sig_id = l2cap_next_sig_id();
651                 channel->state = L2CAP_STATE_WAIT_CONNECT_RSP;
652                 l2cap_send_signaling_packet( channel->con_handle, CONNECTION_REQUEST, channel->local_sig_id, channel->psm, channel->local_cid);
653                 l2cap_start_rtx(channel);
654                 break;
655 
656             case L2CAP_STATE_CONFIG:
657                 if (!hci_can_send_acl_packet_now(channel->con_handle)) break;
658                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP){
659                     uint16_t flags = 0;
660                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
661                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT) {
662                         flags = 1;
663                     } else {
664                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP);
665                     }
666                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID){
667                         l2cap_send_signaling_packet(channel->con_handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, L2CAP_CONF_RESULT_UNKNOWN_OPTIONS, 0, NULL);
668                     } else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU){
669                         config_options[0] = 1; // MTU
670                         config_options[1] = 2; // len param
671                         little_endian_store_16( (uint8_t*)&config_options, 2, channel->remote_mtu);
672                         l2cap_send_signaling_packet(channel->con_handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 4, &config_options);
673                         channelStateVarClearFlag(channel,L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
674                     } else {
675                         l2cap_send_signaling_packet(channel->con_handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 0, NULL);
676                     }
677                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
678                 }
679                 else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ){
680                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
681                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_REQ);
682                     channel->local_sig_id = l2cap_next_sig_id();
683                     config_options[0] = 1; // MTU
684                     config_options[1] = 2; // len param
685                     little_endian_store_16( (uint8_t*)&config_options, 2, channel->local_mtu);
686                     l2cap_send_signaling_packet(channel->con_handle, CONFIGURE_REQUEST, channel->local_sig_id, channel->remote_cid, 0, 4, &config_options);
687                     l2cap_start_rtx(channel);
688                 }
689                 if (l2cap_channel_ready_for_open(channel)){
690                     channel->state = L2CAP_STATE_OPEN;
691                     l2cap_emit_channel_opened(channel, 0);  // success
692                 }
693                 break;
694 
695             case L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE:
696                 if (!hci_can_send_acl_packet_now(channel->con_handle)) break;
697                 channel->state = L2CAP_STATE_INVALID;
698                 l2cap_send_signaling_packet( channel->con_handle, DISCONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid);
699                 // 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 :)
700                 l2cap_finialize_channel_close(channel);  // -- remove from list
701                 break;
702 
703             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
704                 if (!hci_can_send_acl_packet_now(channel->con_handle)) break;
705                 channel->local_sig_id = l2cap_next_sig_id();
706                 channel->state = L2CAP_STATE_WAIT_DISCONNECT;
707                 l2cap_send_signaling_packet( channel->con_handle, DISCONNECTION_REQUEST, channel->local_sig_id, channel->remote_cid, channel->local_cid);
708                 break;
709             default:
710                 break;
711         }
712     }
713 
714 #ifdef ENABLE_BLE
715     // send l2cap con paramter update if necessary
716     hci_connections_get_iterator(&it);
717     while(btstack_linked_list_iterator_has_next(&it)){
718         hci_connection_t * connection = (hci_connection_t *) btstack_linked_list_iterator_next(&it);
719         if (connection->address_type != BD_ADDR_TYPE_LE_PUBLIC && connection->address_type != BD_ADDR_TYPE_LE_RANDOM) continue;
720         if (!hci_can_send_acl_packet_now(connection->con_handle)) continue;
721         switch (connection->le_con_parameter_update_state){
722             case CON_PARAMETER_UPDATE_SEND_REQUEST:
723                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_NONE;
724                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_REQUEST, connection->le_con_param_update_identifier,
725                                                connection->le_conn_interval_min, connection->le_conn_interval_max, connection->le_conn_latency, connection->le_supervision_timeout);
726                 break;
727             case CON_PARAMETER_UPDATE_SEND_RESPONSE:
728                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_CHANGE_HCI_CON_PARAMETERS;
729                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_RESPONSE, connection->le_con_param_update_identifier, 0);
730                 break;
731             case CON_PARAMETER_UPDATE_DENY:
732                 connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_NONE;
733                 l2cap_send_le_signaling_packet(connection->con_handle, CONNECTION_PARAMETER_UPDATE_RESPONSE, connection->le_con_param_update_identifier, 1);
734                 break;
735             default:
736                 break;
737         }
738     }
739 #endif
740 
741     // log_info("l2cap_run: exit");
742 }
743 
744 uint16_t l2cap_max_mtu(void){
745     return HCI_ACL_PAYLOAD_SIZE - L2CAP_HEADER_SIZE;
746 }
747 
748 uint16_t l2cap_max_le_mtu(void){
749     return l2cap_max_mtu();
750 }
751 
752 static void l2cap_handle_connection_complete(hci_con_handle_t con_handle, l2cap_channel_t * channel){
753     if (channel->state == L2CAP_STATE_WAIT_CONNECTION_COMPLETE || channel->state == L2CAP_STATE_WILL_SEND_CREATE_CONNECTION) {
754         log_info("l2cap_handle_connection_complete expected state");
755         // success, start l2cap handshake
756         channel->con_handle = con_handle;
757         // check remote SSP feature first
758         channel->state = L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES;
759     }
760 }
761 
762 static void l2cap_handle_remote_supported_features_received(l2cap_channel_t * channel){
763     if (channel->state != L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES) return;
764 
765     // we have been waiting for remote supported features, if both support SSP,
766     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));
767     if (gap_ssp_supported_on_both_sides(channel->con_handle) && !l2cap_security_level_0_allowed_for_PSM(channel->psm)){
768         // request security level 2
769         channel->state = L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE;
770         gap_request_security_level(channel->con_handle, LEVEL_2);
771         return;
772     }
773     // fine, go ahead
774     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
775 }
776 
777 /**
778  * @brief Creates L2CAP channel to the PSM of a remote device with baseband address. A new baseband connection will be initiated if necessary.
779  * @param packet_handler
780  * @param address
781  * @param psm
782  * @param mtu
783  * @param local_cid
784  */
785 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){
786     log_info("L2CAP_CREATE_CHANNEL addr %s psm 0x%x mtu %u", bd_addr_to_str(address), psm, mtu);
787 
788     // alloc structure
789     l2cap_channel_t * channel = btstack_memory_l2cap_channel_get();
790     if (!channel) {
791         return BTSTACK_MEMORY_ALLOC_FAILED;
792     }
793 
794      // Init memory (make valgrind happy)
795     memset(channel, 0, sizeof(l2cap_channel_t));
796     // limit local mtu to max acl packet length - l2cap header
797     if (mtu > l2cap_max_mtu()) {
798         mtu = l2cap_max_mtu();
799     }
800 
801     // fill in
802     bd_addr_copy(channel->address, address);
803     channel->psm = psm;
804     channel->con_handle = 0;
805     channel->packet_handler = channel_packet_handler;
806     channel->remote_mtu = L2CAP_MINIMAL_MTU;
807     channel->local_mtu = mtu;
808     channel->local_cid = l2cap_next_local_cid();
809 
810     // set initial state
811     channel->state = L2CAP_STATE_WILL_SEND_CREATE_CONNECTION;
812     channel->state_var = L2CAP_CHANNEL_STATE_VAR_NONE;
813     channel->remote_sig_id = L2CAP_SIG_ID_INVALID;
814     channel->local_sig_id = L2CAP_SIG_ID_INVALID;
815     channel->required_security_level = LEVEL_0;
816 
817     // add to connections list
818     btstack_linked_list_add(&l2cap_channels, (btstack_linked_item_t *) channel);
819 
820     // store local_cid
821     if (out_local_cid){
822        *out_local_cid = channel->local_cid;
823     }
824 
825     // check if hci connection is already usable
826     hci_connection_t * conn = hci_connection_for_bd_addr_and_type(address, BD_ADDR_TYPE_CLASSIC);
827     if (conn){
828         log_info("l2cap_create_channel, hci connection already exists");
829         l2cap_handle_connection_complete(conn->con_handle, channel);
830         // check if remote supported fearures are already received
831         if (conn->bonding_flags & BONDING_RECEIVED_REMOTE_FEATURES) {
832             l2cap_handle_remote_supported_features_received(channel);
833         }
834     }
835 
836     l2cap_run();
837 
838     return 0;
839 }
840 
841 void
842 l2cap_disconnect(uint16_t local_cid, uint8_t reason){
843     log_info("L2CAP_DISCONNECT local_cid 0x%x reason 0x%x", local_cid, reason);
844     // find channel for local_cid
845     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
846     if (channel) {
847         channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST;
848     }
849     // process
850     l2cap_run();
851 }
852 
853 static void l2cap_handle_connection_failed_for_addr(bd_addr_t address, uint8_t status){
854     btstack_linked_list_iterator_t it;
855     btstack_linked_list_iterator_init(&it, &l2cap_channels);
856     while (btstack_linked_list_iterator_has_next(&it)){
857         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
858         if ( bd_addr_cmp( channel->address, address) != 0) continue;
859         // channel for this address found
860         switch (channel->state){
861             case L2CAP_STATE_WAIT_CONNECTION_COMPLETE:
862             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
863                 // failure, forward error code
864                 l2cap_emit_channel_opened(channel, status);
865                 // discard channel
866                 l2cap_stop_rtx(channel);
867                 btstack_linked_list_iterator_remove(&it);
868                 btstack_memory_l2cap_channel_free(channel);
869                 break;
870             default:
871                 break;
872         }
873     }
874 }
875 
876 static void l2cap_handle_connection_success_for_addr(bd_addr_t address, hci_con_handle_t handle){
877     btstack_linked_list_iterator_t it;
878     btstack_linked_list_iterator_init(&it, &l2cap_channels);
879     while (btstack_linked_list_iterator_has_next(&it)){
880         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
881         if ( ! bd_addr_cmp( channel->address, address) ){
882             l2cap_handle_connection_complete(handle, channel);
883         }
884     }
885     // process
886     l2cap_run();
887 }
888 
889 static void l2cap_notify_channel_can_send(void){
890     btstack_linked_list_iterator_t it;
891     btstack_linked_list_iterator_init(&it, &l2cap_channels);
892     while (btstack_linked_list_iterator_has_next(&it)){
893         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
894         if (!channel->waiting_for_can_send_now) continue;
895         if (!hci_can_send_acl_packet_now(channel->con_handle)) continue;
896         channel->waiting_for_can_send_now = 0;
897         l2cap_emit_can_send_now(channel->packet_handler, channel->local_cid);
898     }
899 
900     int i;
901     for (i=0;i<L2CAP_FIXED_CHANNEL_TABLE_SIZE;i++){
902         if (!fixed_channels[i].callback) continue;
903         if (!fixed_channels[i].waiting_for_can_send_now) continue;
904         int can_send;
905         if (l2cap_fixed_channel_table_index_is_le(i)){
906             can_send = hci_can_send_acl_le_packet_now();
907         } else {
908             can_send = hci_can_send_acl_classic_packet_now();
909         }
910         if (!can_send) continue;
911         fixed_channels[i].waiting_for_can_send_now = 0;
912         l2cap_emit_can_send_now(fixed_channels[i].callback, l2cap_fixed_channel_table_channel_id_for_index(i));
913     }
914 }
915 
916 static void l2cap_hci_event_handler(uint8_t packet_type, uint16_t cid, uint8_t *packet, uint16_t size){
917 
918     bd_addr_t address;
919     hci_con_handle_t handle;
920     btstack_linked_list_iterator_t it;
921     int hci_con_used;
922 
923     switch(hci_event_packet_get_type(packet)){
924 
925         // handle connection complete events
926         case HCI_EVENT_CONNECTION_COMPLETE:
927             reverse_bd_addr(&packet[5], address);
928             if (packet[2] == 0){
929                 handle = little_endian_read_16(packet, 3);
930                 l2cap_handle_connection_success_for_addr(address, handle);
931             } else {
932                 l2cap_handle_connection_failed_for_addr(address, packet[2]);
933             }
934             break;
935 
936         // handle successful create connection cancel command
937         case HCI_EVENT_COMMAND_COMPLETE:
938             if (HCI_EVENT_IS_COMMAND_COMPLETE(packet, hci_create_connection_cancel)) {
939                 if (packet[5] == 0){
940                     reverse_bd_addr(&packet[6], address);
941                     // CONNECTION TERMINATED BY LOCAL HOST (0X16)
942                     l2cap_handle_connection_failed_for_addr(address, 0x16);
943                 }
944             }
945             l2cap_run();    // try sending signaling packets first
946             break;
947 
948         case HCI_EVENT_COMMAND_STATUS:
949             l2cap_run();    // try sending signaling packets first
950             break;
951 
952         // handle disconnection complete events
953         case HCI_EVENT_DISCONNECTION_COMPLETE:
954             // send l2cap disconnect events for all channels on this handle and free them
955             handle = little_endian_read_16(packet, 3);
956             btstack_linked_list_iterator_init(&it, &l2cap_channels);
957             while (btstack_linked_list_iterator_has_next(&it)){
958                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
959                 if (channel->con_handle != handle) continue;
960                 l2cap_emit_channel_closed(channel);
961                 l2cap_stop_rtx(channel);
962                 btstack_linked_list_iterator_remove(&it);
963                 btstack_memory_l2cap_channel_free(channel);
964             }
965             break;
966 
967         // Notify channel packet handler if they can send now
968         case HCI_EVENT_TRANSPORT_PACKET_SENT:
969         case HCI_EVENT_NUMBER_OF_COMPLETED_PACKETS:
970             l2cap_run();    // try sending signaling packets first
971             l2cap_notify_channel_can_send();
972             break;
973 
974         // HCI Connection Timeouts
975         case L2CAP_EVENT_TIMEOUT_CHECK:
976             handle = little_endian_read_16(packet, 2);
977             if (gap_get_connection_type(handle) != GAP_CONNECTION_ACL) break;
978             if (hci_authentication_active_for_handle(handle)) break;
979             hci_con_used = 0;
980             btstack_linked_list_iterator_init(&it, &l2cap_channels);
981             while (btstack_linked_list_iterator_has_next(&it)){
982                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
983                 if (channel->con_handle != handle) continue;
984                 hci_con_used = 1;
985                 break;
986             }
987             if (hci_con_used) break;
988             if (!hci_can_send_command_packet_now()) break;
989             hci_send_cmd(&hci_disconnect, handle, 0x13); // remote closed connection
990             break;
991 
992         case HCI_EVENT_READ_REMOTE_SUPPORTED_FEATURES_COMPLETE:
993             handle = little_endian_read_16(packet, 3);
994             btstack_linked_list_iterator_init(&it, &l2cap_channels);
995             while (btstack_linked_list_iterator_has_next(&it)){
996                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
997                 if (channel->con_handle != handle) continue;
998                 l2cap_handle_remote_supported_features_received(channel);
999                 break;
1000             }
1001             break;
1002 
1003         case GAP_EVENT_SECURITY_LEVEL:
1004             handle = little_endian_read_16(packet, 2);
1005             log_info("l2cap - security level update");
1006             btstack_linked_list_iterator_init(&it, &l2cap_channels);
1007             while (btstack_linked_list_iterator_has_next(&it)){
1008                 l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
1009                 if (channel->con_handle != handle) continue;
1010 
1011                 log_info("l2cap - state %u", channel->state);
1012 
1013                 gap_security_level_t actual_level = (gap_security_level_t) packet[4];
1014                 gap_security_level_t required_level = channel->required_security_level;
1015 
1016                 switch (channel->state){
1017                     case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
1018                         if (actual_level >= required_level){
1019                             channel->state = L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT;
1020                             l2cap_emit_connection_request(channel);
1021                         } else {
1022                             channel->reason = 0x0003; // security block
1023                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
1024                         }
1025                         break;
1026 
1027                     case L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE:
1028                         if (actual_level >= required_level){
1029                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
1030                         } else {
1031                             // disconnnect, authentication not good enough
1032                             hci_disconnect_security_block(handle);
1033                         }
1034                         break;
1035 
1036                     default:
1037                         break;
1038                 }
1039             }
1040             break;
1041 
1042         default:
1043             break;
1044     }
1045 
1046     l2cap_run();
1047 }
1048 
1049 static void l2cap_handle_disconnect_request(l2cap_channel_t *channel, uint16_t identifier){
1050     channel->remote_sig_id = identifier;
1051     channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE;
1052     l2cap_run();
1053 }
1054 
1055 static void l2cap_register_signaling_response(hci_con_handle_t handle, uint8_t code, uint8_t sig_id, uint16_t data){
1056     // Vol 3, Part A, 4.3: "The DCID and SCID fields shall be ignored when the result field indi- cates the connection was refused."
1057     if (signaling_responses_pending < NR_PENDING_SIGNALING_RESPONSES) {
1058         signaling_responses[signaling_responses_pending].handle = handle;
1059         signaling_responses[signaling_responses_pending].code = code;
1060         signaling_responses[signaling_responses_pending].sig_id = sig_id;
1061         signaling_responses[signaling_responses_pending].data = data;
1062         signaling_responses_pending++;
1063         l2cap_run();
1064     }
1065 }
1066 
1067 static void l2cap_handle_connection_request(hci_con_handle_t handle, uint8_t sig_id, uint16_t psm, uint16_t source_cid){
1068 
1069     // log_info("l2cap_handle_connection_request for handle %u, psm %u cid 0x%02x", handle, psm, source_cid);
1070     l2cap_service_t *service = l2cap_get_service(psm);
1071     if (!service) {
1072         // 0x0002 PSM not supported
1073         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0002);
1074         return;
1075     }
1076 
1077     hci_connection_t * hci_connection = hci_connection_for_handle( handle );
1078     if (!hci_connection) {
1079         //
1080         log_error("no hci_connection for handle %u", handle);
1081         return;
1082     }
1083 
1084     // alloc structure
1085     // log_info("l2cap_handle_connection_request register channel");
1086     l2cap_channel_t * channel = btstack_memory_l2cap_channel_get();
1087     if (!channel){
1088         // 0x0004 No resources available
1089         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0004);
1090         return;
1091     }
1092     // Init memory (make valgrind happy)
1093     memset(channel, 0, sizeof(l2cap_channel_t));
1094     // fill in
1095     bd_addr_copy(channel->address, hci_connection->address);
1096     channel->psm = psm;
1097     channel->con_handle = handle;
1098     channel->packet_handler = service->packet_handler;
1099     channel->local_cid  = l2cap_next_local_cid();
1100     channel->remote_cid = source_cid;
1101     channel->local_mtu  = service->mtu;
1102     channel->remote_mtu = L2CAP_DEFAULT_MTU;
1103     channel->remote_sig_id = sig_id;
1104     channel->required_security_level = service->required_security_level;
1105 
1106     // limit local mtu to max acl packet length - l2cap header
1107     if (channel->local_mtu > l2cap_max_mtu()) {
1108         channel->local_mtu = l2cap_max_mtu();
1109     }
1110 
1111     // set initial state
1112     channel->state =     L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE;
1113     channel->state_var = L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND;
1114 
1115     // add to connections list
1116     btstack_linked_list_add(&l2cap_channels, (btstack_linked_item_t *) channel);
1117 
1118     // assert security requirements
1119     gap_request_security_level(handle, channel->required_security_level);
1120 }
1121 
1122 void l2cap_accept_connection(uint16_t local_cid){
1123     log_info("L2CAP_ACCEPT_CONNECTION local_cid 0x%x", local_cid);
1124     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
1125     if (!channel) {
1126         log_error("l2cap_accept_connection called but local_cid 0x%x not found", local_cid);
1127         return;
1128     }
1129 
1130     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT;
1131 
1132     // process
1133     l2cap_run();
1134 }
1135 
1136 void l2cap_decline_connection(uint16_t local_cid, uint8_t reason){
1137     log_info("L2CAP_DECLINE_CONNECTION local_cid 0x%x, reason %x", local_cid, reason);
1138     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid( local_cid);
1139     if (!channel) {
1140         log_error( "l2cap_decline_connection called but local_cid 0x%x not found", local_cid);
1141         return;
1142     }
1143     channel->state  = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
1144     channel->reason = reason;
1145     l2cap_run();
1146 }
1147 
1148 static void l2cap_signaling_handle_configure_request(l2cap_channel_t *channel, uint8_t *command){
1149 
1150     channel->remote_sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1151 
1152     uint16_t flags = little_endian_read_16(command, 6);
1153     if (flags & 1) {
1154         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
1155     }
1156 
1157     // accept the other's configuration options
1158     uint16_t end_pos = 4 + little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1159     uint16_t pos     = 8;
1160     while (pos < end_pos){
1161         uint8_t option_hint = command[pos] >> 7;
1162         uint8_t option_type = command[pos] & 0x7f;
1163         log_info("l2cap cid %u, hint %u, type %u", channel->local_cid, option_hint, option_type);
1164         pos++;
1165         uint8_t length = command[pos++];
1166         // MTU { type(8): 1, len(8):2, MTU(16) }
1167         if (option_type == 1 && length == 2){
1168             channel->remote_mtu = little_endian_read_16(command, pos);
1169             // log_info("l2cap cid 0x%02x, remote mtu %u", channel->local_cid, channel->remote_mtu);
1170             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
1171         }
1172         // Flush timeout { type(8):2, len(8): 2, Flush Timeout(16)}
1173         if (option_type == 2 && length == 2){
1174             channel->flush_timeout = little_endian_read_16(command, pos);
1175         }
1176         // check for unknown options
1177         if (option_hint == 0 && (option_type == 0 || option_type >= 0x07)){
1178             log_info("l2cap cid %u, unknown options", channel->local_cid);
1179             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID);
1180         }
1181         pos += length;
1182     }
1183 }
1184 
1185 static int l2cap_channel_ready_for_open(l2cap_channel_t *channel){
1186     // log_info("l2cap_channel_ready_for_open 0x%02x", channel->state_var);
1187     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP) == 0) return 0;
1188     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP) == 0) return 0;
1189     // addition check that fixes re-entrance issue causing l2cap event channel opened twice
1190     if (channel->state == L2CAP_STATE_OPEN) return 0;
1191     return 1;
1192 }
1193 
1194 
1195 static void l2cap_signaling_handler_channel(l2cap_channel_t *channel, uint8_t *command){
1196 
1197     uint8_t  code       = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1198     uint8_t  identifier = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1199     uint16_t result = 0;
1200 
1201     log_info("L2CAP signaling handler code %u, state %u", code, channel->state);
1202 
1203     // handle DISCONNECT REQUESTS seperately
1204     if (code == DISCONNECTION_REQUEST){
1205         switch (channel->state){
1206             case L2CAP_STATE_CONFIG:
1207             case L2CAP_STATE_OPEN:
1208             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
1209             case L2CAP_STATE_WAIT_DISCONNECT:
1210                 l2cap_handle_disconnect_request(channel, identifier);
1211                 break;
1212 
1213             default:
1214                 // ignore in other states
1215                 break;
1216         }
1217         return;
1218     }
1219 
1220     // @STATEMACHINE(l2cap)
1221     switch (channel->state) {
1222 
1223         case L2CAP_STATE_WAIT_CONNECT_RSP:
1224             switch (code){
1225                 case CONNECTION_RESPONSE:
1226                     l2cap_stop_rtx(channel);
1227                     result = little_endian_read_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1228                     switch (result) {
1229                         case 0:
1230                             // successful connection
1231                             channel->remote_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1232                             channel->state = L2CAP_STATE_CONFIG;
1233                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1234                             break;
1235                         case 1:
1236                             // connection pending. get some coffee, but start the ERTX
1237                             l2cap_start_ertx(channel);
1238                             break;
1239                         default:
1240                             // channel closed
1241                             channel->state = L2CAP_STATE_CLOSED;
1242                             // map l2cap connection response result to BTstack status enumeration
1243                             l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result);
1244 
1245                             // drop link key if security block
1246                             if (L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result == L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_SECURITY){
1247                                 gap_drop_link_key_for_bd_addr(channel->address);
1248                             }
1249 
1250                             // discard channel
1251                             btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
1252                             btstack_memory_l2cap_channel_free(channel);
1253                             break;
1254                     }
1255                     break;
1256 
1257                 default:
1258                     //@TODO: implement other signaling packets
1259                     break;
1260             }
1261             break;
1262 
1263         case L2CAP_STATE_CONFIG:
1264             result = little_endian_read_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1265             switch (code) {
1266                 case CONFIGURE_REQUEST:
1267                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
1268                     l2cap_signaling_handle_configure_request(channel, command);
1269                     if (!(channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT)){
1270                         // only done if continuation not set
1271                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_REQ);
1272                     }
1273                     break;
1274                 case CONFIGURE_RESPONSE:
1275                     l2cap_stop_rtx(channel);
1276                     switch (result){
1277                         case 0: // success
1278                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP);
1279                             break;
1280                         case 4: // pending
1281                             l2cap_start_ertx(channel);
1282                             break;
1283                         default:
1284                             // retry on negative result
1285                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1286                             break;
1287                     }
1288                     break;
1289                 default:
1290                     break;
1291             }
1292             if (l2cap_channel_ready_for_open(channel)){
1293                 // for open:
1294                 channel->state = L2CAP_STATE_OPEN;
1295                 l2cap_emit_channel_opened(channel, 0);
1296             }
1297             break;
1298 
1299         case L2CAP_STATE_WAIT_DISCONNECT:
1300             switch (code) {
1301                 case DISCONNECTION_RESPONSE:
1302                     l2cap_finialize_channel_close(channel);
1303                     break;
1304                 default:
1305                     //@TODO: implement other signaling packets
1306                     break;
1307             }
1308             break;
1309 
1310         case L2CAP_STATE_CLOSED:
1311             // @TODO handle incoming requests
1312             break;
1313 
1314         case L2CAP_STATE_OPEN:
1315             //@TODO: implement other signaling packets, e.g. re-configure
1316             break;
1317         default:
1318             break;
1319     }
1320     // log_info("new state %u", channel->state);
1321 }
1322 
1323 
1324 static void l2cap_signaling_handler_dispatch( hci_con_handle_t handle, uint8_t * command){
1325 
1326     // get code, signalind identifier and command len
1327     uint8_t code   = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1328     uint8_t sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1329 
1330     // not for a particular channel, and not CONNECTION_REQUEST, ECHO_[REQUEST|RESPONSE], INFORMATION_REQUEST
1331     if (code < 1 || code == ECHO_RESPONSE || code > INFORMATION_REQUEST){
1332         l2cap_register_signaling_response(handle, COMMAND_REJECT, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1333         return;
1334     }
1335 
1336     // general commands without an assigned channel
1337     switch(code) {
1338 
1339         case CONNECTION_REQUEST: {
1340             uint16_t psm =        little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1341             uint16_t source_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+2);
1342             l2cap_handle_connection_request(handle, sig_id, psm, source_cid);
1343             return;
1344         }
1345 
1346         case ECHO_REQUEST:
1347             l2cap_register_signaling_response(handle, code, sig_id, 0);
1348             return;
1349 
1350         case INFORMATION_REQUEST: {
1351             uint16_t infoType = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1352             l2cap_register_signaling_response(handle, code, sig_id, infoType);
1353             return;
1354         }
1355 
1356         default:
1357             break;
1358     }
1359 
1360 
1361     // Get potential destination CID
1362     uint16_t dest_cid = little_endian_read_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1363 
1364     // Find channel for this sig_id and connection handle
1365     btstack_linked_list_iterator_t it;
1366     btstack_linked_list_iterator_init(&it, &l2cap_channels);
1367     while (btstack_linked_list_iterator_has_next(&it)){
1368         l2cap_channel_t * channel = (l2cap_channel_t *) btstack_linked_list_iterator_next(&it);
1369         if (channel->con_handle != handle) continue;
1370         if (code & 1) {
1371             // match odd commands (responses) by previous signaling identifier
1372             if (channel->local_sig_id == sig_id) {
1373                 l2cap_signaling_handler_channel(channel, command);
1374                 break;
1375             }
1376         } else {
1377             // match even commands (requests) by local channel id
1378             if (channel->local_cid == dest_cid) {
1379                 l2cap_signaling_handler_channel(channel, command);
1380                 break;
1381             }
1382         }
1383     }
1384 }
1385 
1386 static void l2cap_acl_handler(uint8_t packet_type, uint8_t *packet, uint16_t size ){
1387 
1388     // Get Channel ID
1389     uint16_t channel_id = READ_L2CAP_CHANNEL_ID(packet);
1390     hci_con_handle_t handle = READ_ACL_CONNECTION_HANDLE(packet);
1391 
1392     switch (channel_id) {
1393 
1394         case L2CAP_CID_SIGNALING: {
1395 
1396             uint16_t command_offset = 8;
1397             while (command_offset < size) {
1398 
1399                 // handle signaling commands
1400                 l2cap_signaling_handler_dispatch(handle, &packet[command_offset]);
1401 
1402                 // increment command_offset
1403                 command_offset += L2CAP_SIGNALING_COMMAND_DATA_OFFSET + little_endian_read_16(packet, command_offset + L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1404             }
1405             break;
1406         }
1407 
1408         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
1409             if (fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL].callback) {
1410                 (*fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_ATTRIBUTE_PROTOCOL].callback)(ATT_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1411             }
1412             break;
1413 
1414         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
1415             if (fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL].callback) {
1416                 (*fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_SECURITY_MANAGER_PROTOCOL].callback)(SM_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1417             }
1418             break;
1419 
1420         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
1421             if (fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL].callback) {
1422                 (*fixed_channels[L2CAP_FIXED_CHANNEL_TABLE_INDEX_CONNECTIONLESS_CHANNEL].callback)(UCD_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1423             }
1424             break;
1425 
1426         case L2CAP_CID_SIGNALING_LE: {
1427             switch (packet[8]){
1428                 case CONNECTION_PARAMETER_UPDATE_RESPONSE: {
1429                     uint16_t result = little_endian_read_16(packet, 12);
1430                     l2cap_emit_connection_parameter_update_response(handle, result);
1431                     break;
1432                 }
1433                 case CONNECTION_PARAMETER_UPDATE_REQUEST: {
1434                     uint8_t event[10];
1435                     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_REQUEST;
1436                     event[1] = 8;
1437                     memcpy(&event[2], &packet[12], 8);
1438 
1439                     hci_connection_t * connection = hci_connection_for_handle(handle);
1440                     if (connection){
1441                         if (connection->role != HCI_ROLE_MASTER){
1442                             // reject command without notifying upper layer when not in master role
1443                             uint8_t sig_id = packet[COMPLETE_L2CAP_HEADER + 1];
1444                             l2cap_register_signaling_response(handle, COMMAND_REJECT_LE, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1445                             break;
1446                         }
1447                         int update_parameter = 1;
1448                         le_connection_parameter_range_t existing_range;
1449                         gap_get_connection_parameter_range(existing_range);
1450                         uint16_t le_conn_interval_min = little_endian_read_16(packet,12);
1451                         uint16_t le_conn_interval_max = little_endian_read_16(packet,14);
1452                         uint16_t le_conn_latency = little_endian_read_16(packet,16);
1453                         uint16_t le_supervision_timeout = little_endian_read_16(packet,18);
1454 
1455                         if (le_conn_interval_min < existing_range.le_conn_interval_min) update_parameter = 0;
1456                         if (le_conn_interval_max > existing_range.le_conn_interval_max) update_parameter = 0;
1457 
1458                         if (le_conn_latency < existing_range.le_conn_latency_min) update_parameter = 0;
1459                         if (le_conn_latency > existing_range.le_conn_latency_max) update_parameter = 0;
1460 
1461                         if (le_supervision_timeout < existing_range.le_supervision_timeout_min) update_parameter = 0;
1462                         if (le_supervision_timeout > existing_range.le_supervision_timeout_max) update_parameter = 0;
1463 
1464                         if (update_parameter){
1465                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_SEND_RESPONSE;
1466                             connection->le_conn_interval_min = le_conn_interval_min;
1467                             connection->le_conn_interval_max = le_conn_interval_max;
1468                             connection->le_conn_latency = le_conn_latency;
1469                             connection->le_supervision_timeout = le_supervision_timeout;
1470                         } else {
1471                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_DENY;
1472                         }
1473                         connection->le_con_param_update_identifier = packet[COMPLETE_L2CAP_HEADER + 1];
1474                     }
1475 
1476                     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
1477                     if (!l2cap_event_packet_handler) break;
1478                     (*l2cap_event_packet_handler)( HCI_EVENT_PACKET, 0, event, sizeof(event));
1479                     break;
1480                 }
1481                 default: {
1482                     uint8_t sig_id = packet[COMPLETE_L2CAP_HEADER + 1];
1483                     l2cap_register_signaling_response(handle, COMMAND_REJECT_LE, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1484                     break;
1485                 }
1486             }
1487             break;
1488         }
1489 
1490         default: {
1491             // Find channel for this channel_id and connection handle
1492             l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(channel_id);
1493             if (channel) {
1494                 l2cap_dispatch_to_channel(channel, L2CAP_DATA_PACKET, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1495             }
1496             break;
1497         }
1498     }
1499 
1500     l2cap_run();
1501 }
1502 
1503 // finalize closed channel - l2cap_handle_disconnect_request & DISCONNECTION_RESPONSE
1504 void l2cap_finialize_channel_close(l2cap_channel_t *channel){
1505     channel->state = L2CAP_STATE_CLOSED;
1506     l2cap_emit_channel_closed(channel);
1507     // discard channel
1508     l2cap_stop_rtx(channel);
1509     btstack_linked_list_remove(&l2cap_channels, (btstack_linked_item_t *) channel);
1510     btstack_memory_l2cap_channel_free(channel);
1511 }
1512 
1513 static l2cap_service_t * l2cap_get_service_internal(btstack_linked_list_t * services, uint16_t psm){
1514     btstack_linked_list_iterator_t it;
1515     btstack_linked_list_iterator_init(&it, services);
1516     while (btstack_linked_list_iterator_has_next(&it)){
1517         l2cap_service_t * service = (l2cap_service_t *) btstack_linked_list_iterator_next(&it);
1518         if ( service->psm == psm){
1519             return service;
1520         };
1521     }
1522     return NULL;
1523 }
1524 
1525 static inline l2cap_service_t * l2cap_get_service(uint16_t psm){
1526     return l2cap_get_service_internal(&l2cap_services, psm);
1527 }
1528 
1529 
1530 uint8_t l2cap_register_service(btstack_packet_handler_t service_packet_handler, uint16_t psm, uint16_t mtu, gap_security_level_t security_level){
1531 
1532     log_info("L2CAP_REGISTER_SERVICE psm 0x%x mtu %u", psm, mtu);
1533 
1534     // check for alread registered psm
1535     // TODO: emit error event
1536     l2cap_service_t *service = l2cap_get_service(psm);
1537     if (service) {
1538         log_error("l2cap_register_service: PSM %u already registered", psm);
1539         return L2CAP_SERVICE_ALREADY_REGISTERED;
1540     }
1541 
1542     // alloc structure
1543     // TODO: emit error event
1544     service = btstack_memory_l2cap_service_get();
1545     if (!service) {
1546         log_error("l2cap_register_service: no memory for l2cap_service_t");
1547         return BTSTACK_MEMORY_ALLOC_FAILED;
1548     }
1549 
1550     // fill in
1551     service->psm = psm;
1552     service->mtu = mtu;
1553     service->packet_handler = service_packet_handler;
1554     service->required_security_level = security_level;
1555 
1556     // add to services list
1557     btstack_linked_list_add(&l2cap_services, (btstack_linked_item_t *) service);
1558 
1559     // enable page scan
1560     gap_connectable_control(1);
1561 
1562     return 0;
1563 }
1564 
1565 void l2cap_unregister_service(uint16_t psm){
1566 
1567     log_info("L2CAP_UNREGISTER_SERVICE psm 0x%x", psm);
1568 
1569     l2cap_service_t *service = l2cap_get_service(psm);
1570     if (!service) return;
1571     btstack_linked_list_remove(&l2cap_services, (btstack_linked_item_t *) service);
1572     btstack_memory_l2cap_service_free(service);
1573 
1574     // disable page scan when no services registered
1575     if (!btstack_linked_list_empty(&l2cap_services)) return;
1576     gap_connectable_control(0);
1577 }
1578 
1579 // Bluetooth 4.0 - allows to register handler for Attribute Protocol and Security Manager Protocol
1580 void l2cap_register_fixed_channel(btstack_packet_handler_t the_packet_handler, uint16_t channel_id) {
1581     int index = l2cap_fixed_channel_table_index_for_channel_id(channel_id);
1582     if (index < 0) return;
1583     fixed_channels[index].callback = the_packet_handler;
1584 }
1585 
1586 #ifdef ENABLE_BLE
1587 
1588 
1589 #if 0
1590 static inline l2cap_service_t * l2cap_le_get_service(uint16_t psm){
1591     return l2cap_get_service_internal(&l2cap_le_services, psm);
1592 }
1593 /**
1594  * @brief Regster L2CAP LE Credit Based Flow Control Mode service
1595  * @param
1596  */
1597 void l2cap_le_register_service(btstack_packet_handler_t packet_handler, uint16_t psm,
1598     uint16_t mtu, uint16_t mps, uint16_t initial_credits, gap_security_level_t security_level){
1599 
1600     log_info("L2CAP_LE_REGISTER_SERVICE psm 0x%x mtu %u connection %p", psm, mtu, connection);
1601 
1602     // check for alread registered psm
1603     // TODO: emit error event
1604     l2cap_service_t *service = l2cap_le_get_service(psm);
1605     if (service) {
1606         log_error("l2cap_le_register_service_internal: PSM %u already registered", psm);
1607         l2cap_emit_service_registered(connection, L2CAP_SERVICE_ALREADY_REGISTERED, psm);
1608         return;
1609     }
1610 
1611     // alloc structure
1612     // TODO: emit error event
1613     service = btstack_memory_l2cap_service_get();
1614     if (!service) {
1615         log_error("l2cap_register_service_internal: no memory for l2cap_service_t");
1616         l2cap_emit_service_registered(connection, BTSTACK_MEMORY_ALLOC_FAILED, psm);
1617         return;
1618     }
1619 
1620     // fill in
1621     service->psm = psm;
1622     service->mtu = mtu;
1623     service->mps = mps;
1624     service->packet_handler = packet_handler;
1625     service->required_security_level = security_level;
1626 
1627     // add to services list
1628     btstack_linked_list_add(&l2cap_le_services, (btstack_linked_item_t *) service);
1629 
1630     // done
1631     l2cap_emit_service_registered(connection, 0, psm);
1632 }
1633 
1634 void l2cap_le_unregister_service(uint16_t psm) {
1635 
1636     log_info("L2CAP_LE_UNREGISTER_SERVICE psm 0x%x", psm);
1637 
1638     l2cap_service_t *service = l2cap_le_get_service(psm);
1639     if (!service) return;
1640     btstack_linked_list_remove(&l2cap_le_services, (btstack_linked_item_t *) service);
1641     btstack_memory_l2cap_service_free(service);
1642 }
1643 #endif
1644 #endif
1645