xref: /btstack/src/l2cap.c (revision 8bcac1fdaacd430263e5fa5bf6997813b920728b)
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 "debug.h"
50 #include "btstack_memory.h"
51 
52 #include <stdarg.h>
53 #include <string.h>
54 
55 #include <stdio.h>
56 
57 // nr of buffered acl packets in outgoing queue to get max performance
58 #define NR_BUFFERED_ACL_PACKETS 3
59 
60 // used to cache l2cap rejects, echo, and informational requests
61 #define NR_PENDING_SIGNALING_RESPONSES 3
62 
63 // offsets for L2CAP SIGNALING COMMANDS
64 #define L2CAP_SIGNALING_COMMAND_CODE_OFFSET   0
65 #define L2CAP_SIGNALING_COMMAND_SIGID_OFFSET  1
66 #define L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET 2
67 #define L2CAP_SIGNALING_COMMAND_DATA_OFFSET   4
68 
69 static void null_packet_handler(void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
70 static void l2cap_packet_handler(uint8_t packet_type, uint8_t *packet, uint16_t size);
71 
72 // used to cache l2cap rejects, echo, and informational requests
73 static l2cap_signaling_response_t signaling_responses[NR_PENDING_SIGNALING_RESPONSES];
74 static int signaling_responses_pending;
75 
76 static linked_list_t l2cap_channels;
77 static linked_list_t l2cap_services;
78 static void (*packet_handler) (void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) = null_packet_handler;
79 static int new_credits_blocked = 0;
80 
81 static btstack_packet_handler_t attribute_protocol_packet_handler;
82 static btstack_packet_handler_t security_protocol_packet_handler;
83 static btstack_packet_handler_t connectionless_channel_packet_handler;
84 static uint8_t require_security_level2_for_outgoing_sdp;
85 
86 // prototypes
87 static void l2cap_finialize_channel_close(l2cap_channel_t *channel);
88 static l2cap_service_t * l2cap_get_service(uint16_t psm);
89 static void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status);
90 static void l2cap_emit_channel_closed(l2cap_channel_t *channel);
91 static void l2cap_emit_connection_request(l2cap_channel_t *channel);
92 static int l2cap_channel_ready_for_open(l2cap_channel_t *channel);
93 
94 
95 void l2cap_init(void){
96     new_credits_blocked = 0;
97     signaling_responses_pending = 0;
98 
99     l2cap_channels = NULL;
100     l2cap_services = NULL;
101 
102     packet_handler = null_packet_handler;
103     attribute_protocol_packet_handler = NULL;
104     security_protocol_packet_handler = NULL;
105     connectionless_channel_packet_handler = NULL;
106 
107     require_security_level2_for_outgoing_sdp = 0;
108 
109     //
110     // register callback with HCI
111     //
112     hci_register_packet_handler(&l2cap_packet_handler);
113     hci_connectable_control(0); // no services yet
114 }
115 
116 
117 /** Register L2CAP packet handlers */
118 static void null_packet_handler(void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
119 }
120 void l2cap_register_packet_handler(void (*handler)(void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size)){
121     packet_handler = handler;
122 }
123 
124 //  notify client/protocol handler
125 void l2cap_dispatch(l2cap_channel_t *channel, uint8_t type, uint8_t * data, uint16_t size){
126     if (channel->packet_handler) {
127         (* (channel->packet_handler))(type, channel->local_cid, data, size);
128     } else {
129         (*packet_handler)(channel->connection, type, channel->local_cid, data, size);
130     }
131 }
132 
133 void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status) {
134     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",
135              status, bd_addr_to_str(channel->address), channel->handle, channel->psm,
136              channel->local_cid, channel->remote_cid, channel->local_mtu, channel->remote_mtu, channel->flush_timeout);
137     uint8_t event[23];
138     event[0] = L2CAP_EVENT_CHANNEL_OPENED;
139     event[1] = sizeof(event) - 2;
140     event[2] = status;
141     bt_flip_addr(&event[3], channel->address);
142     bt_store_16(event,  9, channel->handle);
143     bt_store_16(event, 11, channel->psm);
144     bt_store_16(event, 13, channel->local_cid);
145     bt_store_16(event, 15, channel->remote_cid);
146     bt_store_16(event, 17, channel->local_mtu);
147     bt_store_16(event, 19, channel->remote_mtu);
148     bt_store_16(event, 21, channel->flush_timeout);
149     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
150     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
151 }
152 
153 void l2cap_emit_channel_closed(l2cap_channel_t *channel) {
154     log_info("L2CAP_EVENT_CHANNEL_CLOSED local_cid 0x%x", channel->local_cid);
155     uint8_t event[4];
156     event[0] = L2CAP_EVENT_CHANNEL_CLOSED;
157     event[1] = sizeof(event) - 2;
158     bt_store_16(event, 2, channel->local_cid);
159     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
160     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
161 }
162 
163 void l2cap_emit_connection_request(l2cap_channel_t *channel) {
164     log_info("L2CAP_EVENT_INCOMING_CONNECTION addr %s handle 0x%x psm 0x%x local_cid 0x%x remote_cid 0x%x",
165              bd_addr_to_str(channel->address), channel->handle,  channel->psm, channel->local_cid, channel->remote_cid);
166     uint8_t event[16];
167     event[0] = L2CAP_EVENT_INCOMING_CONNECTION;
168     event[1] = sizeof(event) - 2;
169     bt_flip_addr(&event[2], channel->address);
170     bt_store_16(event,  8, channel->handle);
171     bt_store_16(event, 10, channel->psm);
172     bt_store_16(event, 12, channel->local_cid);
173     bt_store_16(event, 14, channel->remote_cid);
174     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
175     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
176 }
177 
178 void l2cap_emit_connection_parameter_update_response(uint16_t handle, uint16_t result){
179     uint8_t event[6];
180     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_RESPONSE;
181     event[1] = 4;
182     bt_store_16(event, 2, handle);
183     bt_store_16(event, 4, result);
184     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
185     (*packet_handler)(NULL, HCI_EVENT_PACKET, 0, event, sizeof(event));
186 }
187 
188 static void l2cap_emit_service_registered(void *connection, uint8_t status, uint16_t psm){
189     log_info("L2CAP_EVENT_SERVICE_REGISTERED status 0x%x psm 0x%x", status, psm);
190     uint8_t event[5];
191     event[0] = L2CAP_EVENT_SERVICE_REGISTERED;
192     event[1] = sizeof(event) - 2;
193     event[2] = status;
194     bt_store_16(event, 3, psm);
195     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
196     (*packet_handler)(connection, HCI_EVENT_PACKET, 0, event, sizeof(event));
197 }
198 
199 void l2cap_emit_credits(l2cap_channel_t *channel, uint8_t credits) {
200 
201     log_info("L2CAP_EVENT_CREDITS local_cid 0x%x credits %u", channel->local_cid, credits);
202     // track credits
203     channel->packets_granted += credits;
204 
205     uint8_t event[5];
206     event[0] = L2CAP_EVENT_CREDITS;
207     event[1] = sizeof(event) - 2;
208     bt_store_16(event, 2, channel->local_cid);
209     event[4] = credits;
210     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
211     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
212 }
213 
214 void l2cap_block_new_credits(uint8_t blocked){
215     new_credits_blocked = blocked;
216 }
217 
218 void l2cap_hand_out_credits(void){
219 
220     if (new_credits_blocked) return;    // we're told not to. used by daemon
221 
222     linked_list_iterator_t it;
223     linked_list_iterator_init(&it, &l2cap_channels);
224     while (linked_list_iterator_has_next(&it)){
225         l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
226         if (!hci_number_free_acl_slots_for_handle(channel->handle)) return;
227         if (channel->state != L2CAP_STATE_OPEN) continue;
228         if (hci_number_outgoing_packets(channel->handle) < NR_BUFFERED_ACL_PACKETS && channel->packets_granted == 0) {
229             l2cap_emit_credits(channel, 1);
230         }
231     }
232 }
233 
234 l2cap_channel_t * l2cap_get_channel_for_local_cid(uint16_t local_cid){
235     linked_list_iterator_t it;
236     linked_list_iterator_init(&it, &l2cap_channels);
237     while (linked_list_iterator_has_next(&it)){
238         l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
239         if ( channel->local_cid == local_cid) {
240             return channel;
241         }
242     }
243     return NULL;
244 }
245 
246 int  l2cap_can_send_packet_now(uint16_t local_cid){
247     l2cap_channel_t *channel = l2cap_get_channel_for_local_cid(local_cid);
248     if (!channel) return 0;
249     if (!channel->packets_granted) return 0;
250     return hci_can_send_acl_packet_now(channel->handle);
251 }
252 
253 // @deprecated
254 int l2cap_can_send_connectionless_packet_now(void){
255     // TODO provide real handle
256     return l2cap_can_send_fixed_channel_packet_now(0x1234);
257 }
258 
259 int  l2cap_can_send_fixed_channel_packet_now(uint16_t handle){
260     return hci_can_send_acl_packet_now(handle);
261 }
262 
263 uint16_t l2cap_get_remote_mtu_for_local_cid(uint16_t local_cid){
264     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
265     if (channel) {
266         return channel->remote_mtu;
267     }
268     return 0;
269 }
270 
271 static l2cap_channel_t * l2cap_channel_for_rtx_timer(timer_source_t * ts){
272     linked_list_iterator_t it;
273     linked_list_iterator_init(&it, &l2cap_channels);
274     while (linked_list_iterator_has_next(&it)){
275         l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
276         if ( &channel->rtx == ts) {
277             return channel;
278         }
279     }
280     return NULL;
281 }
282 
283 static void l2cap_rtx_timeout(timer_source_t * ts){
284     l2cap_channel_t * channel = l2cap_channel_for_rtx_timer(ts);
285     if (!ts) return;
286 
287     log_info("l2cap_rtx_timeout for local cid 0x%02x", channel->local_cid);
288 
289     // "When terminating the channel, it is not necessary to send a L2CAP_DisconnectReq
290     //  and enter WAIT_DISCONNECT state. Channels can be transitioned directly to the CLOSED state."
291     // notify client
292     l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_RTX_TIMEOUT);
293 
294     // discard channel
295     // no need to stop timer here, it is removed from list during timer callback
296     linked_list_remove(&l2cap_channels, (linked_item_t *) channel);
297     btstack_memory_l2cap_channel_free(channel);
298 }
299 
300 static void l2cap_stop_rtx(l2cap_channel_t * channel){
301     log_info("l2cap_stop_rtx for local cid 0x%02x", channel->local_cid);
302     run_loop_remove_timer(&channel->rtx);
303 }
304 
305 static void l2cap_start_rtx(l2cap_channel_t * channel){
306     l2cap_stop_rtx(channel);
307     log_info("l2cap_start_rtx for local cid 0x%02x", channel->local_cid);
308     run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
309     run_loop_set_timer(&channel->rtx, L2CAP_RTX_TIMEOUT_MS);
310     run_loop_add_timer(&channel->rtx);
311 }
312 
313 static void l2cap_start_ertx(l2cap_channel_t * channel){
314     log_info("l2cap_start_ertx for local cid 0x%02x", channel->local_cid);
315     l2cap_stop_rtx(channel);
316     run_loop_set_timer_handler(&channel->rtx, l2cap_rtx_timeout);
317     run_loop_set_timer(&channel->rtx, L2CAP_ERTX_TIMEOUT_MS);
318     run_loop_add_timer(&channel->rtx);
319 }
320 
321 void l2cap_require_security_level_2_for_outgoing_sdp(void){
322     require_security_level2_for_outgoing_sdp = 1;
323 }
324 
325 static int l2cap_security_level_0_allowed_for_PSM(uint16_t psm){
326     return (psm == PSM_SDP) && (!require_security_level2_for_outgoing_sdp);
327 }
328 
329 int l2cap_send_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
330 
331     if (!hci_can_send_acl_packet_now(handle)){
332         log_info("l2cap_send_signaling_packet, cannot send");
333         return BTSTACK_ACL_BUFFERS_FULL;
334     }
335 
336     // log_info("l2cap_send_signaling_packet type %u", cmd);
337     hci_reserve_packet_buffer();
338     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
339     va_list argptr;
340     va_start(argptr, identifier);
341     uint16_t len = l2cap_create_signaling_classic(acl_buffer, handle, cmd, identifier, argptr);
342     va_end(argptr);
343     // log_info("l2cap_send_signaling_packet con %u!", handle);
344     return hci_send_acl_packet_buffer(len);
345 }
346 
347 #ifdef HAVE_BLE
348 int l2cap_send_le_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
349 
350     if (!hci_can_send_acl_packet_now(handle)){
351         log_info("l2cap_send_signaling_packet, cannot send");
352         return BTSTACK_ACL_BUFFERS_FULL;
353     }
354 
355     // log_info("l2cap_send_signaling_packet type %u", cmd);
356     hci_reserve_packet_buffer();
357     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
358     va_list argptr;
359     va_start(argptr, identifier);
360     uint16_t len = l2cap_create_signaling_le(acl_buffer, handle, cmd, identifier, argptr);
361     va_end(argptr);
362     // log_info("l2cap_send_signaling_packet con %u!", handle);
363     return hci_send_acl_packet_buffer(len);
364 }
365 #endif
366 
367 uint8_t *l2cap_get_outgoing_buffer(void){
368     return hci_get_outgoing_packet_buffer() + COMPLETE_L2CAP_HEADER; // 8 bytes
369 }
370 
371 int l2cap_reserve_packet_buffer(void){
372     return hci_reserve_packet_buffer();
373 }
374 
375 void l2cap_release_packet_buffer(void){
376     hci_release_packet_buffer();
377 }
378 
379 
380 int l2cap_send_prepared(uint16_t local_cid, uint16_t len){
381 
382     if (!hci_is_packet_buffer_reserved()){
383         log_error("l2cap_send_prepared called without reserving packet first");
384         return BTSTACK_ACL_BUFFERS_FULL;
385     }
386 
387     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
388     if (!channel) {
389         log_error("l2cap_send_prepared no channel for cid 0x%02x", local_cid);
390         return -1;   // TODO: define error
391     }
392 
393     if (channel->packets_granted == 0){
394         log_error("l2cap_send_prepared cid 0x%02x, no credits!", local_cid);
395         return -1;  // TODO: define error
396     }
397 
398     if (!hci_can_send_prepared_acl_packet_now(channel->handle)){
399         log_info("l2cap_send_prepared cid 0x%02x, cannot send", local_cid);
400         return BTSTACK_ACL_BUFFERS_FULL;
401     }
402 
403     --channel->packets_granted;
404 
405     log_debug("l2cap_send_prepared cid 0x%02x, handle %u, 1 credit used, credits left %u;",
406                   local_cid, channel->handle, channel->packets_granted);
407 
408     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
409 
410     int pb = hci_non_flushable_packet_boundary_flag_supported() ? 0x00 : 0x02;
411 
412     // 0 - Connection handle : PB=pb : BC=00
413     bt_store_16(acl_buffer, 0, channel->handle | (pb << 12) | (0 << 14));
414     // 2 - ACL length
415     bt_store_16(acl_buffer, 2,  len + 4);
416     // 4 - L2CAP packet length
417     bt_store_16(acl_buffer, 4,  len + 0);
418     // 6 - L2CAP channel DEST
419     bt_store_16(acl_buffer, 6, channel->remote_cid);
420     // send
421     int err = hci_send_acl_packet_buffer(len+8);
422 
423     l2cap_hand_out_credits();
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     bt_store_16(acl_buffer, 0, handle | (pb << 12) | (0 << 14));
448     // 2 - ACL length
449     bt_store_16(acl_buffer, 2,  len + 4);
450     // 4 - L2CAP packet length
451     bt_store_16(acl_buffer, 4,  len + 0);
452     // 6 - L2CAP channel DEST
453     bt_store_16(acl_buffer, 6, cid);
454     // send
455     int err = hci_send_acl_packet_buffer(len+8);
456 
457     l2cap_hand_out_credits();
458 
459     return err;
460 }
461 
462 int l2cap_send_internal(uint16_t local_cid, uint8_t *data, uint16_t len){
463 
464     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
465     if (!channel) {
466         log_error("l2cap_send_internal no channel for cid 0x%02x", local_cid);
467         return -1;   // TODO: define error
468     }
469 
470     if (len > channel->remote_mtu){
471         log_error("l2cap_send_internal cid 0x%02x, data length exceeds remote MTU.", local_cid);
472         return L2CAP_DATA_LEN_EXCEEDS_REMOTE_MTU;
473     }
474 
475     if (!hci_can_send_acl_packet_now(channel->handle)){
476         log_info("l2cap_send_internal cid 0x%02x, cannot send", local_cid);
477         return BTSTACK_ACL_BUFFERS_FULL;
478     }
479 
480     hci_reserve_packet_buffer();
481     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
482 
483     memcpy(&acl_buffer[8], data, len);
484 
485     return l2cap_send_prepared(local_cid, len);
486 }
487 
488 int l2cap_send_connectionless(uint16_t handle, uint16_t cid, uint8_t *data, uint16_t len){
489 
490     if (!hci_can_send_acl_packet_now(handle)){
491         log_info("l2cap_send_internal cid 0x%02x, cannot send", cid);
492         return BTSTACK_ACL_BUFFERS_FULL;
493     }
494 
495     hci_reserve_packet_buffer();
496     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
497 
498     memcpy(&acl_buffer[8], data, len);
499 
500     return l2cap_send_prepared_connectionless(handle, cid, len);
501 }
502 
503 int l2cap_send_echo_request(uint16_t handle, uint8_t *data, uint16_t len){
504     return l2cap_send_signaling_packet(handle, ECHO_REQUEST, 0x77, len, data);
505 }
506 
507 static inline void channelStateVarSetFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
508     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var | flag);
509 }
510 
511 static inline void channelStateVarClearFlag(l2cap_channel_t *channel, L2CAP_CHANNEL_STATE_VAR flag){
512     channel->state_var = (L2CAP_CHANNEL_STATE_VAR) (channel->state_var & ~flag);
513 }
514 
515 
516 
517 // MARK: L2CAP_RUN
518 // process outstanding signaling tasks
519 void l2cap_run(void){
520 
521     // log_info("l2cap_run: entered");
522 
523     // check pending signaling responses
524     while (signaling_responses_pending){
525 
526         hci_con_handle_t handle = signaling_responses[0].handle;
527 
528         if (!hci_can_send_acl_packet_now(handle)) break;
529 
530         uint8_t  sig_id = signaling_responses[0].sig_id;
531         uint16_t infoType = signaling_responses[0].data;    // INFORMATION_REQUEST
532         uint16_t result   = signaling_responses[0].data;    // CONNECTION_REQUEST, COMMAND_REJECT
533         uint8_t  response_code = signaling_responses[0].code;
534 
535         // remove first item before sending (to avoid sending response mutliple times)
536         signaling_responses_pending--;
537         int i;
538         for (i=0; i < signaling_responses_pending; i++){
539             memcpy(&signaling_responses[i], &signaling_responses[i+1], sizeof(l2cap_signaling_response_t));
540         }
541 
542         switch (response_code){
543             case CONNECTION_REQUEST:
544                 l2cap_send_signaling_packet(handle, CONNECTION_RESPONSE, sig_id, 0, 0, result, 0);
545                 // also disconnect if result is 0x0003 - security blocked
546                 if (result == 0x0003){
547                     hci_disconnect_security_block(handle);
548                 }
549                 break;
550             case ECHO_REQUEST:
551                 l2cap_send_signaling_packet(handle, ECHO_RESPONSE, sig_id, 0, NULL);
552                 break;
553             case INFORMATION_REQUEST:
554                 switch (infoType){
555                     case 1: { // Connectionless MTU
556                         uint16_t connectionless_mtu = hci_max_acl_data_packet_length();
557                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(connectionless_mtu), &connectionless_mtu);
558                         break;
559                     }
560                     case 2: { // Extended Features Supported
561                         // extended features request supported, features: fixed channels, unicast connectionless data reception
562                         uint32_t features = 0x280;
563                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(features), &features);
564                         break;
565                     }
566                     case 3: { // Fixed Channels Supported
567                         uint8_t map[8];
568                         memset(map, 0, 8);
569                         map[0] = 0x01;  // L2CAP Signaling Channel (0x01) + Connectionless reception (0x02)
570                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, sizeof(map), &map);
571                         break;
572                     }
573                     default:
574                         // all other types are not supported
575                         l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 1, 0, NULL);
576                         break;
577                 }
578                 break;
579             case COMMAND_REJECT:
580                 l2cap_send_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
581 #ifdef HAVE_BLE
582             case COMMAND_REJECT_LE:
583                 l2cap_send_le_signaling_packet(handle, COMMAND_REJECT, sig_id, result, 0, NULL);
584                 break;
585 #endif
586             default:
587                 // should not happen
588                 break;
589         }
590     }
591 
592     uint8_t  config_options[4];
593     linked_list_iterator_t it;
594     linked_list_iterator_init(&it, &l2cap_channels);
595     while (linked_list_iterator_has_next(&it)){
596 
597         l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
598         // log_info("l2cap_run: channel %p, state %u, var 0x%02x", channel, channel->state, channel->state_var);
599         switch (channel->state){
600 
601             case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
602             case L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT:
603                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
604                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND) {
605                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND);
606                     l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 1, 0);
607                 }
608                 break;
609 
610             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
611                 if (!hci_can_send_command_packet_now()) break;
612                 // send connection request - set state first
613                 channel->state = L2CAP_STATE_WAIT_CONNECTION_COMPLETE;
614                 // BD_ADDR, Packet_Type, Page_Scan_Repetition_Mode, Reserved, Clock_Offset, Allow_Role_Switch
615                 hci_send_cmd(&hci_create_connection, channel->address, hci_usable_acl_packet_types(), 0, 0, 0, 1);
616                 break;
617 
618             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE:
619                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
620                 channel->state = L2CAP_STATE_INVALID;
621                 l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, channel->reason, 0);
622                 // discard channel - l2cap_finialize_channel_close without sending l2cap close event
623                 l2cap_stop_rtx(channel);
624                 linked_list_iterator_remove(&it);
625                 btstack_memory_l2cap_channel_free(channel);
626                 break;
627 
628             case L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT:
629                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
630                 channel->state = L2CAP_STATE_CONFIG;
631                 channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
632                 l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid, 0, 0);
633                 break;
634 
635             case L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST:
636                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
637                 // success, start l2cap handshake
638                 channel->local_sig_id = l2cap_next_sig_id();
639                 channel->state = L2CAP_STATE_WAIT_CONNECT_RSP;
640                 l2cap_send_signaling_packet( channel->handle, CONNECTION_REQUEST, channel->local_sig_id, channel->psm, channel->local_cid);
641                 l2cap_start_rtx(channel);
642                 break;
643 
644             case L2CAP_STATE_CONFIG:
645                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
646                 if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP){
647                     uint16_t flags = 0;
648                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
649                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT) {
650                         flags = 1;
651                     } else {
652                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP);
653                     }
654                     if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID){
655                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, L2CAP_CONF_RESULT_UNKNOWN_OPTIONS, 0, NULL);
656                     } else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU){
657                         config_options[0] = 1; // MTU
658                         config_options[1] = 2; // len param
659                         bt_store_16( (uint8_t*)&config_options, 2, channel->remote_mtu);
660                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 4, &config_options);
661                         channelStateVarClearFlag(channel,L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
662                     } else {
663                         l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, channel->remote_sig_id, channel->remote_cid, flags, 0, 0, NULL);
664                     }
665                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
666                 }
667                 else if (channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ){
668                     channelStateVarClearFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
669                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SENT_CONF_REQ);
670                     channel->local_sig_id = l2cap_next_sig_id();
671                     config_options[0] = 1; // MTU
672                     config_options[1] = 2; // len param
673                     bt_store_16( (uint8_t*)&config_options, 2, channel->local_mtu);
674                     l2cap_send_signaling_packet(channel->handle, CONFIGURE_REQUEST, channel->local_sig_id, channel->remote_cid, 0, 4, &config_options);
675                     l2cap_start_rtx(channel);
676                 }
677                 if (l2cap_channel_ready_for_open(channel)){
678                     channel->state = L2CAP_STATE_OPEN;
679                     l2cap_emit_channel_opened(channel, 0);  // success
680                     l2cap_emit_credits(channel, 1);
681                 }
682                 break;
683 
684             case L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE:
685                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
686                 channel->state = L2CAP_STATE_INVALID;
687                 l2cap_send_signaling_packet( channel->handle, DISCONNECTION_RESPONSE, channel->remote_sig_id, channel->local_cid, channel->remote_cid);
688                 // 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 :)
689                 l2cap_finialize_channel_close(channel);  // -- remove from list
690                 break;
691 
692             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
693                 if (!hci_can_send_acl_packet_now(channel->handle)) break;
694                 channel->local_sig_id = l2cap_next_sig_id();
695                 channel->state = L2CAP_STATE_WAIT_DISCONNECT;
696                 l2cap_send_signaling_packet( channel->handle, DISCONNECTION_REQUEST, channel->local_sig_id, channel->remote_cid, channel->local_cid);
697                 break;
698             default:
699                 break;
700         }
701     }
702 
703 #ifdef HAVE_BLE
704     // send l2cap con paramter update if necessary
705     hci_connections_get_iterator(&it);
706     while(linked_list_iterator_has_next(&it)){
707         hci_connection_t * connection = (hci_connection_t *) linked_list_iterator_next(&it);
708         int result;
709 
710         switch (connection->le_con_parameter_update_state){
711             case CON_PARAMETER_UPDATE_SEND_RESPONSE:
712                 result = 0;
713                 break;
714             case CON_PARAMETER_UPDATE_DENY:
715                 result = 1;
716                 break;
717             default:
718                 result = -1;
719                 break;
720         }
721         if (result < 0) break;
722 
723         if (!hci_can_send_acl_packet_now(connection->con_handle)) break;
724         hci_reserve_packet_buffer();
725         uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
726         connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_NONE;
727         uint16_t len = l2cap_le_create_connection_parameter_update_response(acl_buffer, connection->con_handle, result);
728         hci_send_acl_packet_buffer(len);
729         if (result == 0){
730             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_CHANGE_HCI_CON_PARAMETERS;
731         }
732     }
733 #endif
734 
735     // log_info("l2cap_run: exit");
736 }
737 
738 uint16_t l2cap_max_mtu(void){
739     return HCI_ACL_PAYLOAD_SIZE - L2CAP_HEADER_SIZE;
740 }
741 
742 uint16_t l2cap_max_le_mtu(void){
743     return l2cap_max_mtu();
744 }
745 
746 static void l2cap_handle_connection_complete(uint16_t handle, l2cap_channel_t * channel){
747     if (channel->state == L2CAP_STATE_WAIT_CONNECTION_COMPLETE || channel->state == L2CAP_STATE_WILL_SEND_CREATE_CONNECTION) {
748         log_info("l2cap_handle_connection_complete expected state");
749         // success, start l2cap handshake
750         channel->handle = handle;
751         channel->local_cid = l2cap_next_local_cid();
752         // check remote SSP feature first
753         channel->state = L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES;
754     }
755 }
756 
757 static void l2cap_handle_remote_supported_features_received(l2cap_channel_t * channel){
758     if (channel->state != L2CAP_STATE_WAIT_REMOTE_SUPPORTED_FEATURES) return;
759 
760     // we have been waiting for remote supported features, if both support SSP,
761     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));
762     if (hci_ssp_supported_on_both_sides(channel->handle) && !l2cap_security_level_0_allowed_for_PSM(channel->psm)){
763         // request security level 2
764         channel->state = L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE;
765         gap_request_security_level(channel->handle, LEVEL_2);
766         return;
767     }
768     // fine, go ahead
769     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
770 }
771 
772 // open outgoing L2CAP channel
773 void l2cap_create_channel_internal(void * connection, btstack_packet_handler_t packet_handler,
774                                    bd_addr_t address, uint16_t psm, uint16_t mtu){
775 
776     log_info("L2CAP_CREATE_CHANNEL_MTU addr %s psm 0x%x mtu %u", bd_addr_to_str(address), psm, mtu);
777 
778     // alloc structure
779     l2cap_channel_t * chan = btstack_memory_l2cap_channel_get();
780     if (!chan) {
781         // emit error event
782         l2cap_channel_t dummy_channel;
783         BD_ADDR_COPY(dummy_channel.address, address);
784         dummy_channel.psm = psm;
785         l2cap_emit_channel_opened(&dummy_channel, BTSTACK_MEMORY_ALLOC_FAILED);
786         return;
787     }
788     // Init memory (make valgrind happy)
789     memset(chan, 0, sizeof(l2cap_channel_t));
790     // limit local mtu to max acl packet length - l2cap header
791     if (mtu > l2cap_max_mtu()) {
792         mtu = l2cap_max_mtu();
793     }
794 
795     // fill in
796     BD_ADDR_COPY(chan->address, address);
797     chan->psm = psm;
798     chan->handle = 0;
799     chan->connection = connection;
800     chan->packet_handler = packet_handler;
801     chan->remote_mtu = L2CAP_MINIMAL_MTU;
802     chan->local_mtu = mtu;
803     chan->packets_granted = 0;
804 
805     // set initial state
806     chan->state = L2CAP_STATE_WILL_SEND_CREATE_CONNECTION;
807     chan->state_var = L2CAP_CHANNEL_STATE_VAR_NONE;
808     chan->remote_sig_id = L2CAP_SIG_ID_INVALID;
809     chan->local_sig_id = L2CAP_SIG_ID_INVALID;
810     chan->required_security_level = LEVEL_0;
811 
812     // add to connections list
813     linked_list_add(&l2cap_channels, (linked_item_t *) chan);
814 
815     // check if hci connection is already usable
816     hci_connection_t * conn = hci_connection_for_bd_addr_and_type(address, BD_ADDR_TYPE_CLASSIC);
817     if (conn){
818         log_info("l2cap_create_channel_internal, hci connection already exists");
819         l2cap_handle_connection_complete(conn->con_handle, chan);
820         // check if remote supported fearures are already received
821         if (conn->bonding_flags & BONDING_RECEIVED_REMOTE_FEATURES) {
822             l2cap_handle_remote_supported_features_received(chan);
823         }
824     }
825 
826     l2cap_run();
827 }
828 
829 void l2cap_disconnect_internal(uint16_t local_cid, uint8_t reason){
830     log_info("L2CAP_DISCONNECT local_cid 0x%x reason 0x%x", local_cid, reason);
831     // find channel for local_cid
832     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
833     if (channel) {
834         channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST;
835     }
836     // process
837     l2cap_run();
838 }
839 
840 static void l2cap_handle_connection_failed_for_addr(bd_addr_t address, uint8_t status){
841     linked_list_iterator_t it;
842     linked_list_iterator_init(&it, &l2cap_channels);
843     while (linked_list_iterator_has_next(&it)){
844         l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
845         if ( BD_ADDR_CMP( channel->address, address) != 0) continue;
846         // channel for this address found
847         switch (channel->state){
848             case L2CAP_STATE_WAIT_CONNECTION_COMPLETE:
849             case L2CAP_STATE_WILL_SEND_CREATE_CONNECTION:
850                 // failure, forward error code
851                 l2cap_emit_channel_opened(channel, status);
852                 // discard channel
853                 l2cap_stop_rtx(channel);
854                 linked_list_iterator_remove(&it);
855                 btstack_memory_l2cap_channel_free(channel);
856                 break;
857             default:
858                 break;
859         }
860     }
861 }
862 
863 static void l2cap_handle_connection_success_for_addr(bd_addr_t address, hci_con_handle_t handle){
864     linked_list_iterator_t it;
865     linked_list_iterator_init(&it, &l2cap_channels);
866     while (linked_list_iterator_has_next(&it)){
867         l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
868         if ( ! BD_ADDR_CMP( channel->address, address) ){
869             l2cap_handle_connection_complete(handle, channel);
870         }
871     }
872     // process
873     l2cap_run();
874 }
875 
876 void l2cap_event_handler(uint8_t *packet, uint16_t size){
877 
878     bd_addr_t address;
879     hci_con_handle_t handle;
880     linked_list_iterator_t it;
881     int hci_con_used;
882 
883     switch(packet[0]){
884 
885         // handle connection complete events
886         case HCI_EVENT_CONNECTION_COMPLETE:
887             bt_flip_addr(address, &packet[5]);
888             if (packet[2] == 0){
889                 handle = READ_BT_16(packet, 3);
890                 l2cap_handle_connection_success_for_addr(address, handle);
891             } else {
892                 l2cap_handle_connection_failed_for_addr(address, packet[2]);
893             }
894             break;
895 
896         // handle successful create connection cancel command
897         case HCI_EVENT_COMMAND_COMPLETE:
898             if ( COMMAND_COMPLETE_EVENT(packet, hci_create_connection_cancel) ) {
899                 if (packet[5] == 0){
900                     bt_flip_addr(address, &packet[6]);
901                     // CONNECTION TERMINATED BY LOCAL HOST (0X16)
902                     l2cap_handle_connection_failed_for_addr(address, 0x16);
903                 }
904             }
905             l2cap_run();    // try sending signaling packets first
906             break;
907 
908         case HCI_EVENT_COMMAND_STATUS:
909             l2cap_run();    // try sending signaling packets first
910             break;
911 
912         // handle disconnection complete events
913         case HCI_EVENT_DISCONNECTION_COMPLETE:
914             // send l2cap disconnect events for all channels on this handle and free them
915             handle = READ_BT_16(packet, 3);
916             linked_list_iterator_init(&it, &l2cap_channels);
917             while (linked_list_iterator_has_next(&it)){
918                 l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
919                 if (channel->handle != handle) continue;
920                 l2cap_emit_channel_closed(channel);
921                 l2cap_stop_rtx(channel);
922                 linked_list_iterator_remove(&it);
923                 btstack_memory_l2cap_channel_free(channel);
924             }
925             break;
926 
927         case HCI_EVENT_NUMBER_OF_COMPLETED_PACKETS:
928             l2cap_run();    // try sending signaling packets first
929             l2cap_hand_out_credits();
930             break;
931 
932         // HCI Connection Timeouts
933         case L2CAP_EVENT_TIMEOUT_CHECK:
934             handle = READ_BT_16(packet, 2);
935             if (hci_authentication_active_for_handle(handle)) break;
936             hci_con_used = 0;
937             linked_list_iterator_init(&it, &l2cap_channels);
938             while (linked_list_iterator_has_next(&it)){
939                 l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
940                 if (channel->handle != handle) continue;
941                 hci_con_used = 1;
942                 break;
943             }
944             if (hci_con_used) break;
945             if (!hci_can_send_command_packet_now()) break;
946             hci_send_cmd(&hci_disconnect, handle, 0x13); // remote closed connection
947             break;
948 
949         case DAEMON_EVENT_HCI_PACKET_SENT:
950             linked_list_iterator_init(&it, &l2cap_channels);
951             while (linked_list_iterator_has_next(&it)){
952                 l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
953                 if (!channel->packet_handler) continue;
954                 (* (channel->packet_handler))(HCI_EVENT_PACKET, channel->local_cid, packet, size);
955             }
956             if (attribute_protocol_packet_handler) {
957                 (*attribute_protocol_packet_handler)(HCI_EVENT_PACKET, 0, packet, size);
958             }
959             if (security_protocol_packet_handler) {
960                 (*security_protocol_packet_handler)(HCI_EVENT_PACKET, 0, packet, size);
961             }
962             if (connectionless_channel_packet_handler) {
963                 (*connectionless_channel_packet_handler)(HCI_EVENT_PACKET, 0, packet, size);
964             }
965             break;
966 
967         case HCI_EVENT_READ_REMOTE_SUPPORTED_FEATURES_COMPLETE:
968             handle = READ_BT_16(packet, 3);
969             linked_list_iterator_init(&it, &l2cap_channels);
970             while (linked_list_iterator_has_next(&it)){
971                 l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
972                 if (channel->handle != handle) continue;
973                 l2cap_handle_remote_supported_features_received(channel);
974                 break;
975             }
976             break;
977 
978         case GAP_SECURITY_LEVEL:
979             handle = READ_BT_16(packet, 2);
980             log_info("l2cap - security level update");
981             linked_list_iterator_init(&it, &l2cap_channels);
982             while (linked_list_iterator_has_next(&it)){
983                 l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
984                 if (channel->handle != handle) continue;
985 
986                 log_info("l2cap - state %u", channel->state);
987 
988                 gap_security_level_t actual_level = (gap_security_level_t) packet[4];
989                 gap_security_level_t required_level = channel->required_security_level;
990 
991                 switch (channel->state){
992                     case L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE:
993                         if (actual_level >= required_level){
994                             channel->state = L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT;
995                             l2cap_emit_connection_request(channel);
996                         } else {
997                             channel->reason = 0x0003; // security block
998                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
999                         }
1000                         break;
1001 
1002                     case L2CAP_STATE_WAIT_OUTGOING_SECURITY_LEVEL_UPDATE:
1003                         if (actual_level >= required_level){
1004                             channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_REQUEST;
1005                         } else {
1006                             // disconnnect, authentication not good enough
1007                             hci_disconnect_security_block(handle);
1008                         }
1009                         break;
1010 
1011                     default:
1012                         break;
1013                 }
1014             }
1015             break;
1016 
1017         default:
1018             break;
1019     }
1020 
1021     // pass on: main packet handler, att and sm packet handlers
1022     (*packet_handler)(NULL, HCI_EVENT_PACKET, 0, packet, size);
1023     if (attribute_protocol_packet_handler){
1024         (*attribute_protocol_packet_handler)(HCI_EVENT_PACKET, 0, packet, size);
1025     }
1026     if (security_protocol_packet_handler) {
1027         (*security_protocol_packet_handler)(HCI_EVENT_PACKET, 0, packet, size);
1028     }
1029     if (connectionless_channel_packet_handler) {
1030         (*connectionless_channel_packet_handler)(HCI_EVENT_PACKET, 0, packet, size);
1031     }
1032 
1033     l2cap_run();
1034 }
1035 
1036 static void l2cap_handle_disconnect_request(l2cap_channel_t *channel, uint16_t identifier){
1037     channel->remote_sig_id = identifier;
1038     channel->state = L2CAP_STATE_WILL_SEND_DISCONNECT_RESPONSE;
1039     l2cap_run();
1040 }
1041 
1042 static void l2cap_register_signaling_response(hci_con_handle_t handle, uint8_t code, uint8_t sig_id, uint16_t data){
1043     // Vol 3, Part A, 4.3: "The DCID and SCID fields shall be ignored when the result field indi- cates the connection was refused."
1044     if (signaling_responses_pending < NR_PENDING_SIGNALING_RESPONSES) {
1045         signaling_responses[signaling_responses_pending].handle = handle;
1046         signaling_responses[signaling_responses_pending].code = code;
1047         signaling_responses[signaling_responses_pending].sig_id = sig_id;
1048         signaling_responses[signaling_responses_pending].data = data;
1049         signaling_responses_pending++;
1050         l2cap_run();
1051     }
1052 }
1053 
1054 static void l2cap_handle_connection_request(hci_con_handle_t handle, uint8_t sig_id, uint16_t psm, uint16_t source_cid){
1055 
1056     // log_info("l2cap_handle_connection_request for handle %u, psm %u cid 0x%02x", handle, psm, source_cid);
1057     l2cap_service_t *service = l2cap_get_service(psm);
1058     if (!service) {
1059         // 0x0002 PSM not supported
1060         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0002);
1061         return;
1062     }
1063 
1064     hci_connection_t * hci_connection = hci_connection_for_handle( handle );
1065     if (!hci_connection) {
1066         //
1067         log_error("no hci_connection for handle %u", handle);
1068         return;
1069     }
1070 
1071     // alloc structure
1072     // log_info("l2cap_handle_connection_request register channel");
1073     l2cap_channel_t * channel = btstack_memory_l2cap_channel_get();
1074     if (!channel){
1075         // 0x0004 No resources available
1076         l2cap_register_signaling_response(handle, CONNECTION_REQUEST, sig_id, 0x0004);
1077         return;
1078     }
1079     // Init memory (make valgrind happy)
1080     memset(channel, 0, sizeof(l2cap_channel_t));
1081     // fill in
1082     BD_ADDR_COPY(channel->address, hci_connection->address);
1083     channel->psm = psm;
1084     channel->handle = handle;
1085     channel->connection = service->connection;
1086     channel->packet_handler = service->packet_handler;
1087     channel->local_cid  = l2cap_next_local_cid();
1088     channel->remote_cid = source_cid;
1089     channel->local_mtu  = service->mtu;
1090     channel->remote_mtu = L2CAP_DEFAULT_MTU;
1091     channel->packets_granted = 0;
1092     channel->remote_sig_id = sig_id;
1093     channel->required_security_level = service->required_security_level;
1094 
1095     // limit local mtu to max acl packet length - l2cap header
1096     if (channel->local_mtu > l2cap_max_mtu()) {
1097         channel->local_mtu = l2cap_max_mtu();
1098     }
1099 
1100     // set initial state
1101     channel->state =     L2CAP_STATE_WAIT_INCOMING_SECURITY_LEVEL_UPDATE;
1102     channel->state_var = L2CAP_CHANNEL_STATE_VAR_SEND_CONN_RESP_PEND;
1103 
1104     // add to connections list
1105     linked_list_add(&l2cap_channels, (linked_item_t *) channel);
1106 
1107     // assert security requirements
1108     gap_request_security_level(handle, channel->required_security_level);
1109 }
1110 
1111 void l2cap_accept_connection_internal(uint16_t local_cid){
1112     log_info("L2CAP_ACCEPT_CONNECTION local_cid 0x%x", local_cid);
1113     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
1114     if (!channel) {
1115         log_error("l2cap_accept_connection_internal called but local_cid 0x%x not found", local_cid);
1116         return;
1117     }
1118 
1119     channel->state = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_ACCEPT;
1120 
1121     // process
1122     l2cap_run();
1123 }
1124 
1125 void l2cap_decline_connection_internal(uint16_t local_cid, uint8_t reason){
1126     log_info("L2CAP_DECLINE_CONNECTION local_cid 0x%x, reason %x", local_cid, reason);
1127     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid( local_cid);
1128     if (!channel) {
1129         log_error( "l2cap_decline_connection_internal called but local_cid 0x%x not found", local_cid);
1130         return;
1131     }
1132     channel->state  = L2CAP_STATE_WILL_SEND_CONNECTION_RESPONSE_DECLINE;
1133     channel->reason = reason;
1134     l2cap_run();
1135 }
1136 
1137 void l2cap_signaling_handle_configure_request(l2cap_channel_t *channel, uint8_t *command){
1138 
1139     channel->remote_sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1140 
1141     uint16_t flags = READ_BT_16(command, 6);
1142     if (flags & 1) {
1143         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT);
1144     }
1145 
1146     // accept the other's configuration options
1147     uint16_t end_pos = 4 + READ_BT_16(command, L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1148     uint16_t pos     = 8;
1149     while (pos < end_pos){
1150         uint8_t option_hint = command[pos] >> 7;
1151         uint8_t option_type = command[pos] & 0x7f;
1152         log_info("l2cap cid %u, hint %u, type %u", channel->local_cid, option_hint, option_type);
1153         pos++;
1154         uint8_t length = command[pos++];
1155         // MTU { type(8): 1, len(8):2, MTU(16) }
1156         if (option_type == 1 && length == 2){
1157             channel->remote_mtu = READ_BT_16(command, pos);
1158             // log_info("l2cap cid 0x%02x, remote mtu %u", channel->local_cid, channel->remote_mtu);
1159             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_MTU);
1160         }
1161         // Flush timeout { type(8):2, len(8): 2, Flush Timeout(16)}
1162         if (option_type == 2 && length == 2){
1163             channel->flush_timeout = READ_BT_16(command, pos);
1164         }
1165         // check for unknown options
1166         if (option_hint == 0 && (option_type == 0 || option_type >= 0x07)){
1167             log_info("l2cap cid %u, unknown options", channel->local_cid);
1168             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_INVALID);
1169         }
1170         pos += length;
1171     }
1172 }
1173 
1174 static int l2cap_channel_ready_for_open(l2cap_channel_t *channel){
1175     // log_info("l2cap_channel_ready_for_open 0x%02x", channel->state_var);
1176     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP) == 0) return 0;
1177     if ((channel->state_var & L2CAP_CHANNEL_STATE_VAR_SENT_CONF_RSP) == 0) return 0;
1178     // addition check that fixes re-entrance issue causing l2cap event channel opened twice
1179     if (channel->state == L2CAP_STATE_OPEN) return 0;
1180     return 1;
1181 }
1182 
1183 
1184 void l2cap_signaling_handler_channel(l2cap_channel_t *channel, uint8_t *command){
1185 
1186     uint8_t  code       = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1187     uint8_t  identifier = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1188     uint16_t result = 0;
1189 
1190     log_info("L2CAP signaling handler code %u, state %u", code, channel->state);
1191 
1192     // handle DISCONNECT REQUESTS seperately
1193     if (code == DISCONNECTION_REQUEST){
1194         switch (channel->state){
1195             case L2CAP_STATE_CONFIG:
1196             case L2CAP_STATE_OPEN:
1197             case L2CAP_STATE_WILL_SEND_DISCONNECT_REQUEST:
1198             case L2CAP_STATE_WAIT_DISCONNECT:
1199                 l2cap_handle_disconnect_request(channel, identifier);
1200                 break;
1201 
1202             default:
1203                 // ignore in other states
1204                 break;
1205         }
1206         return;
1207     }
1208 
1209     // @STATEMACHINE(l2cap)
1210     switch (channel->state) {
1211 
1212         case L2CAP_STATE_WAIT_CONNECT_RSP:
1213             switch (code){
1214                 case CONNECTION_RESPONSE:
1215                     l2cap_stop_rtx(channel);
1216                     result = READ_BT_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1217                     switch (result) {
1218                         case 0:
1219                             // successful connection
1220                             channel->remote_cid = READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1221                             channel->state = L2CAP_STATE_CONFIG;
1222                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1223                             break;
1224                         case 1:
1225                             // connection pending. get some coffee, but start the ERTX
1226                             l2cap_start_ertx(channel);
1227                             break;
1228                         default:
1229                             // channel closed
1230                             channel->state = L2CAP_STATE_CLOSED;
1231                             // map l2cap connection response result to BTstack status enumeration
1232                             l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result);
1233 
1234                             // drop link key if security block
1235                             if (L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result == L2CAP_CONNECTION_RESPONSE_RESULT_REFUSED_SECURITY){
1236                                 hci_drop_link_key_for_bd_addr(channel->address);
1237                             }
1238 
1239                             // discard channel
1240                             linked_list_remove(&l2cap_channels, (linked_item_t *) channel);
1241                             btstack_memory_l2cap_channel_free(channel);
1242                             break;
1243                     }
1244                     break;
1245 
1246                 default:
1247                     //@TODO: implement other signaling packets
1248                     break;
1249             }
1250             break;
1251 
1252         case L2CAP_STATE_CONFIG:
1253             result = READ_BT_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
1254             switch (code) {
1255                 case CONFIGURE_REQUEST:
1256                     channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP);
1257                     l2cap_signaling_handle_configure_request(channel, command);
1258                     if (!(channel->state_var & L2CAP_CHANNEL_STATE_VAR_SEND_CONF_RSP_CONT)){
1259                         // only done if continuation not set
1260                         channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_REQ);
1261                     }
1262                     break;
1263                 case CONFIGURE_RESPONSE:
1264                     l2cap_stop_rtx(channel);
1265                     switch (result){
1266                         case 0: // success
1267                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_RCVD_CONF_RSP);
1268                             break;
1269                         case 4: // pending
1270                             l2cap_start_ertx(channel);
1271                             break;
1272                         default:
1273                             // retry on negative result
1274                             channelStateVarSetFlag(channel, L2CAP_CHANNEL_STATE_VAR_SEND_CONF_REQ);
1275                             break;
1276                     }
1277                     break;
1278                 default:
1279                     break;
1280             }
1281             if (l2cap_channel_ready_for_open(channel)){
1282                 // for open:
1283                 channel->state = L2CAP_STATE_OPEN;
1284                 l2cap_emit_channel_opened(channel, 0);
1285                 l2cap_emit_credits(channel, 1);
1286             }
1287             break;
1288 
1289         case L2CAP_STATE_WAIT_DISCONNECT:
1290             switch (code) {
1291                 case DISCONNECTION_RESPONSE:
1292                     l2cap_finialize_channel_close(channel);
1293                     break;
1294                 default:
1295                     //@TODO: implement other signaling packets
1296                     break;
1297             }
1298             break;
1299 
1300         case L2CAP_STATE_CLOSED:
1301             // @TODO handle incoming requests
1302             break;
1303 
1304         case L2CAP_STATE_OPEN:
1305             //@TODO: implement other signaling packets, e.g. re-configure
1306             break;
1307         default:
1308             break;
1309     }
1310     // log_info("new state %u", channel->state);
1311 }
1312 
1313 
1314 void l2cap_signaling_handler_dispatch( hci_con_handle_t handle, uint8_t * command){
1315 
1316     // get code, signalind identifier and command len
1317     uint8_t code   = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
1318     uint8_t sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
1319 
1320     // not for a particular channel, and not CONNECTION_REQUEST, ECHO_[REQUEST|RESPONSE], INFORMATION_REQUEST
1321     if (code < 1 || code == ECHO_RESPONSE || code > INFORMATION_REQUEST){
1322         l2cap_register_signaling_response(handle, COMMAND_REJECT, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1323         return;
1324     }
1325 
1326     // general commands without an assigned channel
1327     switch(code) {
1328 
1329         case CONNECTION_REQUEST: {
1330             uint16_t psm =        READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1331             uint16_t source_cid = READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+2);
1332             l2cap_handle_connection_request(handle, sig_id, psm, source_cid);
1333             return;
1334         }
1335 
1336         case ECHO_REQUEST:
1337             l2cap_register_signaling_response(handle, code, sig_id, 0);
1338             return;
1339 
1340         case INFORMATION_REQUEST: {
1341             uint16_t infoType = READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1342             l2cap_register_signaling_response(handle, code, sig_id, infoType);
1343             return;
1344         }
1345 
1346         default:
1347             break;
1348     }
1349 
1350 
1351     // Get potential destination CID
1352     uint16_t dest_cid = READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
1353 
1354     // Find channel for this sig_id and connection handle
1355     linked_list_iterator_t it;
1356     linked_list_iterator_init(&it, &l2cap_channels);
1357     while (linked_list_iterator_has_next(&it)){
1358         l2cap_channel_t * channel = (l2cap_channel_t *) linked_list_iterator_next(&it);
1359         if (channel->handle != handle) continue;
1360         if (code & 1) {
1361             // match odd commands (responses) by previous signaling identifier
1362             if (channel->local_sig_id == sig_id) {
1363                 l2cap_signaling_handler_channel(channel, command);
1364                 break;
1365             }
1366         } else {
1367             // match even commands (requests) by local channel id
1368             if (channel->local_cid == dest_cid) {
1369                 l2cap_signaling_handler_channel(channel, command);
1370                 break;
1371             }
1372         }
1373     }
1374 }
1375 
1376 void l2cap_acl_handler( uint8_t *packet, uint16_t size ){
1377 
1378     // Get Channel ID
1379     uint16_t channel_id = READ_L2CAP_CHANNEL_ID(packet);
1380     hci_con_handle_t handle = READ_ACL_CONNECTION_HANDLE(packet);
1381 
1382     switch (channel_id) {
1383 
1384         case L2CAP_CID_SIGNALING: {
1385 
1386             uint16_t command_offset = 8;
1387             while (command_offset < size) {
1388 
1389                 // handle signaling commands
1390                 l2cap_signaling_handler_dispatch(handle, &packet[command_offset]);
1391 
1392                 // increment command_offset
1393                 command_offset += L2CAP_SIGNALING_COMMAND_DATA_OFFSET + READ_BT_16(packet, command_offset + L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
1394             }
1395             break;
1396         }
1397 
1398         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
1399             if (attribute_protocol_packet_handler) {
1400                 (*attribute_protocol_packet_handler)(ATT_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1401             }
1402             break;
1403 
1404         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
1405             if (security_protocol_packet_handler) {
1406                 (*security_protocol_packet_handler)(SM_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1407             }
1408             break;
1409 
1410         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
1411             if (connectionless_channel_packet_handler) {
1412                 (*connectionless_channel_packet_handler)(UCD_DATA_PACKET, handle, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1413             }
1414             break;
1415 
1416         case L2CAP_CID_SIGNALING_LE: {
1417             switch (packet[8]){
1418                 case CONNECTION_PARAMETER_UPDATE_RESPONSE: {
1419                     uint16_t result = READ_BT_16(packet, 12);
1420                     l2cap_emit_connection_parameter_update_response(handle, result);
1421                     break;
1422                 }
1423                 case CONNECTION_PARAMETER_UPDATE_REQUEST: {
1424                     uint8_t event[10];
1425                     event[0] = L2CAP_EVENT_CONNECTION_PARAMETER_UPDATE_REQUEST;
1426                     event[1] = 8;
1427                     memcpy(&event[2], &packet[12], 8);
1428 
1429                     hci_connection_t * connection = hci_connection_for_handle(handle);
1430                     if (connection){
1431                         int update_parameter = 1;
1432                         le_connection_parameter_range_t existing_range = gap_le_get_connection_parameter_range();
1433                         uint16_t le_conn_interval_min = READ_BT_16(packet,12);
1434                         uint16_t le_conn_interval_max = READ_BT_16(packet,14);
1435                         uint16_t le_conn_latency = READ_BT_16(packet,16);
1436                         uint16_t le_supervision_timeout = READ_BT_16(packet,18);
1437 
1438                         if (le_conn_interval_min < existing_range.le_conn_interval_min) update_parameter = 0;
1439                         if (le_conn_interval_max > existing_range.le_conn_interval_max) update_parameter = 0;
1440 
1441                         if (le_conn_latency < existing_range.le_conn_latency_min) update_parameter = 0;
1442                         if (le_conn_latency > existing_range.le_conn_latency_max) update_parameter = 0;
1443 
1444                         if (le_supervision_timeout < existing_range.le_supervision_timeout_min) update_parameter = 0;
1445                         if (le_supervision_timeout > existing_range.le_supervision_timeout_max) update_parameter = 0;
1446 
1447                         if (update_parameter){
1448                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_SEND_RESPONSE;
1449                             connection->le_conn_interval_min = le_conn_interval_min;
1450                             connection->le_conn_interval_max = le_conn_interval_max;
1451                             connection->le_conn_latency = le_conn_latency;
1452                             connection->le_supervision_timeout = le_supervision_timeout;
1453                         } else {
1454                             connection->le_con_parameter_update_state = CON_PARAMETER_UPDATE_DENY;
1455                         }
1456                     }
1457 
1458                     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
1459                     (*packet_handler)(NULL, HCI_EVENT_PACKET, 0, event, sizeof(event));
1460 
1461                     break;
1462                 }
1463                 default: {
1464                     uint8_t sig_id = packet[COMPLETE_L2CAP_HEADER + 1];
1465                     l2cap_register_signaling_response(handle, COMMAND_REJECT_LE, sig_id, L2CAP_REJ_CMD_UNKNOWN);
1466                     break;
1467                 }
1468             }
1469             break;
1470         }
1471 
1472         default: {
1473             // Find channel for this channel_id and connection handle
1474             l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(channel_id);
1475             if (channel) {
1476                 l2cap_dispatch(channel, L2CAP_DATA_PACKET, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
1477             }
1478             break;
1479         }
1480     }
1481 }
1482 
1483 static void l2cap_packet_handler(uint8_t packet_type, uint8_t *packet, uint16_t size){
1484     switch (packet_type) {
1485         case HCI_EVENT_PACKET:
1486             l2cap_event_handler(packet, size);
1487             break;
1488         case HCI_ACL_DATA_PACKET:
1489             l2cap_acl_handler(packet, size);
1490             break;
1491         default:
1492             break;
1493     }
1494     l2cap_run();
1495 }
1496 
1497 // finalize closed channel - l2cap_handle_disconnect_request & DISCONNECTION_RESPONSE
1498 void l2cap_finialize_channel_close(l2cap_channel_t *channel){
1499     channel->state = L2CAP_STATE_CLOSED;
1500     l2cap_emit_channel_closed(channel);
1501     // discard channel
1502     l2cap_stop_rtx(channel);
1503     linked_list_remove(&l2cap_channels, (linked_item_t *) channel);
1504     btstack_memory_l2cap_channel_free(channel);
1505 }
1506 
1507 l2cap_service_t * l2cap_get_service(uint16_t psm){
1508     linked_list_iterator_t it;
1509     linked_list_iterator_init(&it, &l2cap_services);
1510     while (linked_list_iterator_has_next(&it)){
1511         l2cap_service_t * service = (l2cap_service_t *) linked_list_iterator_next(&it);
1512         if ( service->psm == psm){
1513             return service;
1514         };
1515     }
1516     return NULL;
1517 }
1518 
1519 void l2cap_register_service_internal(void *connection, btstack_packet_handler_t packet_handler, uint16_t psm, uint16_t mtu, gap_security_level_t security_level){
1520 
1521     log_info("L2CAP_REGISTER_SERVICE psm 0x%x mtu %u connection %p", psm, mtu, connection);
1522 
1523     // check for alread registered psm
1524     // TODO: emit error event
1525     l2cap_service_t *service = l2cap_get_service(psm);
1526     if (service) {
1527         log_error("l2cap_register_service_internal: PSM %u already registered", psm);
1528         l2cap_emit_service_registered(connection, L2CAP_SERVICE_ALREADY_REGISTERED, psm);
1529         return;
1530     }
1531 
1532     // alloc structure
1533     // TODO: emit error event
1534     service = btstack_memory_l2cap_service_get();
1535     if (!service) {
1536         log_error("l2cap_register_service_internal: no memory for l2cap_service_t");
1537         l2cap_emit_service_registered(connection, BTSTACK_MEMORY_ALLOC_FAILED, psm);
1538         return;
1539     }
1540 
1541     // fill in
1542     service->psm = psm;
1543     service->mtu = mtu;
1544     service->connection = connection;
1545     service->packet_handler = packet_handler;
1546     service->required_security_level = security_level;
1547 
1548     // add to services list
1549     linked_list_add(&l2cap_services, (linked_item_t *) service);
1550 
1551     // enable page scan
1552     hci_connectable_control(1);
1553 
1554     // done
1555     l2cap_emit_service_registered(connection, 0, psm);
1556 }
1557 
1558 void l2cap_unregister_service_internal(void *connection, uint16_t psm){
1559 
1560     log_info("L2CAP_UNREGISTER_SERVICE psm 0x%x", psm);
1561 
1562     l2cap_service_t *service = l2cap_get_service(psm);
1563     if (!service) return;
1564     linked_list_remove(&l2cap_services, (linked_item_t *) service);
1565     btstack_memory_l2cap_service_free(service);
1566 
1567     // disable page scan when no services registered
1568     if (!linked_list_empty(&l2cap_services)) return;
1569     hci_connectable_control(0);
1570 }
1571 
1572 
1573 // Bluetooth 4.0 - allows to register handler for Attribute Protocol and Security Manager Protocol
1574 void l2cap_register_fixed_channel(btstack_packet_handler_t packet_handler, uint16_t channel_id) {
1575     switch(channel_id){
1576         case L2CAP_CID_ATTRIBUTE_PROTOCOL:
1577             attribute_protocol_packet_handler = packet_handler;
1578             break;
1579         case L2CAP_CID_SECURITY_MANAGER_PROTOCOL:
1580             security_protocol_packet_handler = packet_handler;
1581             break;
1582         case L2CAP_CID_CONNECTIONLESS_CHANNEL:
1583             connectionless_channel_packet_handler = packet_handler;
1584             break;
1585     }
1586 }
1587 
1588 #ifdef HAVE_BLE
1589 
1590 // Request LE connection parameter update
1591 int l2cap_le_request_connection_parameter_update(uint16_t handle, uint16_t interval_min, uint16_t interval_max, uint16_t slave_latency, uint16_t timeout_multiplier){
1592     if (!hci_can_send_acl_packet_now(handle)){
1593         log_info("l2cap_send_signaling_packet, cannot send");
1594         return BTSTACK_ACL_BUFFERS_FULL;
1595     }
1596     // log_info("l2cap_send_signaling_packet type %u", cmd);
1597     hci_reserve_packet_buffer();
1598     uint8_t *acl_buffer = hci_get_outgoing_packet_buffer();
1599     uint16_t len = l2cap_le_create_connection_parameter_update_request(acl_buffer, handle, interval_min, interval_max, slave_latency, timeout_multiplier);
1600     return hci_send_acl_packet_buffer(len);
1601 }
1602 #endif
1603 
1604