xref: /btstack/src/l2cap.c (revision 8d371091e8a91bbd46fdc490583b9bc1bef3861f)
1 /*
2  * Copyright (C) 2009 by Matthias Ringwald
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  *
17  * THIS SOFTWARE IS PROVIDED BY MATTHIAS RINGWALD AND CONTRIBUTORS
18  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
20  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL MATTHIAS
21  * RINGWALD OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
22  * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
23  * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
24  * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
25  * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
26  * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF
27  * THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
28  * SUCH DAMAGE.
29  *
30  */
31 
32 /*
33  *  l2cap.c
34  *
35  *  Logical Link Control and Adaption Protocl (L2CAP)
36  *
37  *  Created by Matthias Ringwald on 5/16/09.
38  */
39 
40 #include "l2cap.h"
41 #include "hci.h"
42 #include "hci_dump.h"
43 #include "debug.h"
44 
45 #include <stdarg.h>
46 #include <string.h>
47 
48 #include <stdio.h>
49 
50 // size of HCI ACL + L2CAP Header for regular data packets
51 #define COMPLETE_L2CAP_HEADER 8
52 
53 // minimum signaling MTU
54 #define L2CAP_MINIMAL_MTU 48
55 #define L2CAP_DEFAULT_MTU 672
56 
57 // offsets for L2CAP SIGNALING COMMANDS
58 #define L2CAP_SIGNALING_COMMAND_CODE_OFFSET   0
59 #define L2CAP_SIGNALING_COMMAND_SIGID_OFFSET  1
60 #define L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET 2
61 #define L2CAP_SIGNALING_COMMAND_DATA_OFFSET   4
62 
63 static void null_packet_handler(void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size);
64 static void l2cap_packet_handler(uint8_t packet_type, uint8_t *packet, uint16_t size);
65 
66 static uint8_t * sig_buffer = NULL;
67 static linked_list_t l2cap_channels = NULL;
68 static linked_list_t l2cap_services = NULL;
69 static uint8_t * acl_buffer = NULL;
70 static void (*packet_handler) (void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size) = null_packet_handler;
71 
72 static uint8_t config_options[] = { 1, 2, 150, 0}; // mtu = 48
73 
74 void l2cap_init(){
75     sig_buffer = malloc( L2CAP_MINIMAL_MTU );
76     acl_buffer = malloc( HCI_ACL_3DH5_SIZE);
77 
78     //
79     // register callback with HCI
80     //
81     hci_register_packet_handler(&l2cap_packet_handler);
82 }
83 
84 
85 /** Register L2CAP packet handlers */
86 static void null_packet_handler(void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
87 }
88 void l2cap_register_packet_handler(void (*handler)(void * connection, uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size)){
89     packet_handler = handler;
90 }
91 
92 //  notify client/protocol handler
93 void l2cap_dispatch(l2cap_channel_t *channel, uint8_t type, uint8_t * data, uint16_t size){
94     if (channel->packet_handler) {
95         (* (channel->packet_handler))(type, channel->local_cid, data, size);
96     } else {
97         (*packet_handler)(channel->connection, type, channel->local_cid, data, size);
98     }
99 }
100 
101 void l2cap_emit_channel_opened(l2cap_channel_t *channel, uint8_t status) {
102     uint8_t event[17];
103     event[0] = L2CAP_EVENT_CHANNEL_OPENED;
104     event[1] = sizeof(event) - 2;
105     event[2] = status;
106     bt_flip_addr(&event[3], channel->address);
107     bt_store_16(event,  9, channel->handle);
108     bt_store_16(event, 11, channel->psm);
109     bt_store_16(event, 13, channel->local_cid);
110     bt_store_16(event, 15, channel->remote_cid);
111     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
112     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
113 }
114 
115 void l2cap_emit_channel_closed(l2cap_channel_t *channel) {
116     uint8_t event[4];
117     event[0] = L2CAP_EVENT_CHANNEL_CLOSED;
118     event[1] = sizeof(event) - 2;
119     bt_store_16(event, 2, channel->local_cid);
120     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
121     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
122 }
123 
124 void l2cap_emit_connection_request(l2cap_channel_t *channel) {
125     uint8_t event[16];
126     event[0] = L2CAP_EVENT_INCOMING_CONNECTION;
127     event[1] = sizeof(event) - 2;
128     bt_flip_addr(&event[2], channel->address);
129     bt_store_16(event,  8, channel->handle);
130     bt_store_16(event, 10, channel->psm);
131     bt_store_16(event, 12, channel->local_cid);
132     bt_store_16(event, 14, channel->remote_cid);
133     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
134     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
135 }
136 
137 void l2cap_emit_credits(l2cap_channel_t *channel, uint8_t credits) {
138     // track credits
139     channel->packets_granted += credits;
140     log_dbg("l2cap_emit_credits for cid %u, credits now: %u (+%u)\n", channel->local_cid, channel->packets_granted, credits);
141 
142     uint8_t event[5];
143     event[0] = L2CAP_EVENT_CREDITS;
144     event[1] = sizeof(event) - 2;
145     bt_store_16(event, 2, channel->local_cid);
146     event[4] = credits;
147     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
148     l2cap_dispatch(channel, HCI_EVENT_PACKET, event, sizeof(event));
149 }
150 
151 void l2cap_hand_out_credits(){
152     linked_item_t *it;
153     for (it = (linked_item_t *) l2cap_channels; it ; it = it->next){
154         if (!hci_number_free_acl_slots()) return;
155         l2cap_channel_t * channel = (l2cap_channel_t *) it;
156         if (hci_number_outgoing_packets(channel->handle) < 2 && channel->packets_granted == 0) {
157             l2cap_emit_credits(channel, 1);
158         }
159     }
160 }
161 
162 l2cap_channel_t * l2cap_get_channel_for_local_cid(uint16_t local_cid){
163     linked_item_t *it;
164     for (it = (linked_item_t *) l2cap_channels; it ; it = it->next){
165         l2cap_channel_t * channel = (l2cap_channel_t *) it;
166         if ( channel->local_cid == local_cid) {
167             return channel;
168         }
169     }
170     return NULL;
171 }
172 
173 uint16_t l2cap_get_remote_mtu_for_local_cid(uint16_t local_cid){
174     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
175     if (channel) {
176         return channel->remote_mtu;
177     }
178     return 0;
179 }
180 
181 int l2cap_send_signaling_packet(hci_con_handle_t handle, L2CAP_SIGNALING_COMMANDS cmd, uint8_t identifier, ...){
182     // printf("l2cap_send_signaling_packet type %u\n", cmd);
183     va_list argptr;
184     va_start(argptr, identifier);
185     uint16_t len = l2cap_create_signaling_internal(sig_buffer, handle, cmd, identifier, argptr);
186     va_end(argptr);
187     return hci_send_acl_packet(sig_buffer, len);
188 }
189 
190 int l2cap_send_internal(uint16_t local_cid, uint8_t *data, uint16_t len){
191 
192     // check for free places on BT module
193     if (!hci_number_free_acl_slots()) return -1;
194 
195     int err = 0;
196 
197     // find channel for local_cid, construct l2cap packet and send
198     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
199     if (channel) {
200         // track sending
201         ++channel->packets_outgoing;
202         if (channel->packets_granted > 0){
203             --channel->packets_granted;
204         } else {
205             log_err("l2cap_send_internal cid %u, no credits!\n", local_cid);
206         }
207         log_dbg("l2cap_send_internal cid %u, 1 credit used, credits left %u; outgoing count %u\n",
208                 local_cid, channel->packets_granted, channel->packets_outgoing);
209 
210         // 0 - Connection handle : PB=10 : BC=00
211         bt_store_16(acl_buffer, 0, channel->handle | (2 << 12) | (0 << 14));
212         // 2 - ACL length
213         bt_store_16(acl_buffer, 2,  len + 4);
214         // 4 - L2CAP packet length
215         bt_store_16(acl_buffer, 4,  len + 0);
216         // 6 - L2CAP channel DEST
217         bt_store_16(acl_buffer, 6, channel->remote_cid);
218         // 8 - data
219         memcpy(&acl_buffer[8], data, len);
220 
221         // send
222         err = hci_send_acl_packet(acl_buffer, len+8);
223     }
224     return err;
225 }
226 
227 // open outgoing L2CAP channel
228 void l2cap_create_channel_internal(void * connection, btstack_packet_handler_t packet_handler, bd_addr_t address, uint16_t psm){
229 
230     // alloc structure
231     l2cap_channel_t * chan = malloc(sizeof(l2cap_channel_t));
232     // TODO: emit error event
233     if (!chan) return;
234 
235     // fill in
236     BD_ADDR_COPY(chan->address, address);
237     chan->psm = psm;
238     chan->handle = 0;
239     chan->connection = connection;
240     chan->packet_handler = packet_handler;
241     chan->remote_mtu = L2CAP_MINIMAL_MTU;
242 
243     // flow control
244     chan->packets_granted = 0;
245     chan->packets_outgoing = 0;
246 
247     // set initial state
248     chan->state = L2CAP_STATE_CLOSED;
249     chan->sig_id = L2CAP_SIG_ID_INVALID;
250 
251     // add to connections list
252     linked_list_add(&l2cap_channels, (linked_item_t *) chan);
253 
254     // send connection request
255     // BD_ADDR, Packet_Type, Page_Scan_Repetition_Mode, Reserved, Clock_Offset, Allow_Role_Switch
256     hci_send_cmd(&hci_create_connection, address, 0x18, 0, 0, 0, 0);
257 }
258 
259 void l2cap_disconnect_internal(uint16_t local_cid, uint8_t reason){
260     // find channel for local_cid
261     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
262     if (channel) {
263         channel->sig_id = l2cap_next_sig_id();
264         l2cap_send_signaling_packet( channel->handle, DISCONNECTION_REQUEST, channel->sig_id, channel->remote_cid, channel->local_cid);
265         channel->state = L2CAP_STATE_WAIT_DISCONNECT;
266     }
267 }
268 
269 static void l2cap_handle_connection_failed_for_addr(bd_addr_t address, uint8_t status){
270     linked_item_t *it;
271     for (it = (linked_item_t *) l2cap_channels; it ; it = it->next){
272         l2cap_channel_t * channel = (l2cap_channel_t *) it;
273         if ( ! BD_ADDR_CMP( channel->address, address) ){
274             if (channel->state == L2CAP_STATE_CLOSED) {
275                 // failure, forward error code
276                 l2cap_emit_channel_opened(channel, status);
277                 // discard channel
278                 linked_list_remove(&l2cap_channels, (linked_item_t *) channel);
279                 free (channel);
280             }
281         }
282     }
283 }
284 
285 static void l2cap_handle_connection_success_for_addr(bd_addr_t address, hci_con_handle_t handle){
286     linked_item_t *it;
287     for (it = (linked_item_t *) l2cap_channels; it ; it = it->next){
288         l2cap_channel_t * channel = (l2cap_channel_t *) it;
289         if ( ! BD_ADDR_CMP( channel->address, address) ){
290             if (channel->state == L2CAP_STATE_CLOSED) {
291                 // success, start l2cap handshake
292                 channel->handle = handle;
293                 channel->sig_id = l2cap_next_sig_id();
294                 channel->local_cid = l2cap_next_local_cid();
295                 channel->state = L2CAP_STATE_WAIT_CONNECT_RSP;
296                 l2cap_send_signaling_packet( channel->handle, CONNECTION_REQUEST, channel->sig_id, channel->psm, channel->local_cid);
297             }
298         }
299     }
300 }
301 
302 void l2cap_event_handler( uint8_t *packet, uint16_t size ){
303 
304     bd_addr_t address;
305     hci_con_handle_t handle;
306     linked_item_t *it;
307     int i;
308 
309     switch(packet[0]){
310 
311         // handle connection complete events
312         case HCI_EVENT_CONNECTION_COMPLETE:
313             bt_flip_addr(address, &packet[5]);
314             if (packet[2] == 0){
315                 handle = READ_BT_16(packet, 3);
316                 l2cap_handle_connection_success_for_addr(address, handle);
317             } else {
318                 l2cap_handle_connection_failed_for_addr(address, packet[2]);
319             }
320             break;
321 
322         // handle successful create connection cancel command
323         case HCI_EVENT_COMMAND_COMPLETE:
324             if ( COMMAND_COMPLETE_EVENT(packet, hci_create_connection_cancel) ) {
325                 if (packet[5] == 0){
326                     bt_flip_addr(address, &packet[6]);
327                     // CONNECTION TERMINATED BY LOCAL HOST (0X16)
328                     l2cap_handle_connection_failed_for_addr(address, 0x16);
329                 }
330             }
331             break;
332 
333         // handle disconnection complete events
334         case HCI_EVENT_DISCONNECTION_COMPLETE:
335             // send l2cap disconnect events for all channels on this handle
336             handle = READ_BT_16(packet, 3);
337             // only access next element to allows for removal
338             for (it = (linked_item_t *) &l2cap_channels; it->next ; it = it->next){
339                 l2cap_channel_t * channel = (l2cap_channel_t *) it->next;
340                 if ( channel->handle == handle ){
341                     // update prev item before free'ing next element
342                     it->next = it->next->next;
343                     l2cap_finialize_channel_close(channel);
344                 }
345             }
346             break;
347 
348         case HCI_EVENT_NUMBER_OF_COMPLETED_PACKETS:
349             for (i=0; i<packet[2];i++){
350                 handle = READ_BT_16(packet, 3 + 2*i);
351                 uint16_t num_packets = READ_BT_16(packet, 3 + packet[2]*2 + 2*i);
352                 while (num_packets) {
353 
354                     // find channels with max nr of pending outgoing packets
355                     l2cap_channel_t * fullest_channel = NULL;
356                     int max_nr_pending = 0;
357                     for (it = (linked_item_t *) &l2cap_channels; it->next ; it = it->next){
358                         l2cap_channel_t * channel = (l2cap_channel_t *) it->next;
359                         if (channel->packets_outgoing > max_nr_pending){
360                             fullest_channel = channel;
361                             max_nr_pending  = channel->packets_outgoing;
362                         }
363                     }
364 
365                     // decrease packets
366                     if (fullest_channel) {
367                         fullest_channel->packets_outgoing--;
368                         log_dbg("hci_number_completed_packet (l2cap) for cid %u, outgoing count %u\n",
369                                 fullest_channel->local_cid, fullest_channel->packets_outgoing);
370                     } else {
371                         log_err("hci_number_completed_packet but no outgoing packet in records\n");
372                     }
373 
374                     // handled!
375                     num_packets--;
376                 }
377             }
378             l2cap_hand_out_credits();
379             break;
380 
381         // HCI Connection Timeouts
382         case L2CAP_EVENT_TIMEOUT_CHECK:
383             handle = READ_BT_16(packet, 2);
384             l2cap_channel_t * channel;
385             int used = 0;
386             for (it = (linked_item_t *) l2cap_channels; it ; it = it->next){
387                 channel = (l2cap_channel_t *) it;
388                 if (channel->handle == handle) {
389                     used = 1;
390                 }
391             }
392             if (!used) {
393                 hci_send_cmd(&hci_disconnect, handle, 0x13); // remote closed connection
394             }
395             break;
396 
397         default:
398             break;
399     }
400 
401     // pass on
402     (*packet_handler)(NULL, HCI_EVENT_PACKET, 0, packet, size);
403 }
404 
405 static void l2cap_handle_disconnect_request(l2cap_channel_t *channel, uint16_t identifier){
406     l2cap_send_signaling_packet( channel->handle, DISCONNECTION_RESPONSE, identifier, channel->local_cid, channel->remote_cid);
407     l2cap_finialize_channel_close(channel);
408 }
409 
410 static void l2cap_handle_connection_request(hci_con_handle_t handle, uint8_t sig_id, uint16_t psm, uint16_t source_cid){
411 
412     // printf("l2cap_handle_connection_request for handle %u, psm %u cid %u\n", handle, psm, source_cid);
413     l2cap_service_t *service = l2cap_get_service(psm);
414     if (!service) {
415         // 0x0002 PSM not supported
416         // printf("l2cap_handle_connection_request no PSM for psm %u/n", psm);
417         l2cap_send_signaling_packet(handle, CONNECTION_RESPONSE, sig_id, 0, 0, 0x0002, 0);
418         return;
419     }
420 
421     hci_connection_t * hci_connection = connection_for_handle( handle );
422     if (!hci_connection) {
423         fprintf(stderr, "no hci_connection for handle %u\n", handle);
424         // TODO: emit error
425         return;
426     }
427     // alloc structure
428     // printf("l2cap_handle_connection_request register channel\n");
429     l2cap_channel_t * channel = malloc(sizeof(l2cap_channel_t));
430     // TODO: emit error event
431     if (!channel) return;
432 
433     // fill in
434     BD_ADDR_COPY(channel->address, hci_connection->address);
435     channel->psm = psm;
436     channel->handle = handle;
437     channel->connection = service->connection;
438     channel->packet_handler = service->packet_handler;
439     channel->local_cid  = l2cap_next_local_cid();
440     channel->remote_cid = source_cid;
441     channel->remote_mtu = L2CAP_MINIMAL_MTU;
442 
443     // set initial state
444     channel->state = L2CAP_STATE_WAIT_CLIENT_ACCEPT_OR_REJECT;
445 
446     // temp. store req sig id
447     channel->sig_id = sig_id;
448 
449     // add to connections list
450     linked_list_add(&l2cap_channels, (linked_item_t *) channel);
451 
452     // emit incoming connection request
453     l2cap_emit_connection_request(channel);
454 }
455 
456 void l2cap_accept_connection_internal(uint16_t local_cid){
457     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(local_cid);
458     if (!channel) {
459         fprintf(stderr, "l2cap_accept_connection_internal called but local_cid 0x%x not found", local_cid);
460         return;
461     }
462 
463     // accept connection
464     l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->sig_id, channel->local_cid, channel->remote_cid, 0, 0);
465 
466     // set real sig and state and start config
467     channel->sig_id = l2cap_next_sig_id();
468     channel->state  = L2CAP_STATE_WAIT_CONFIG_REQ_RSP_OR_CONFIG_REQ;
469     l2cap_send_signaling_packet(channel->handle, CONFIGURE_REQUEST, channel->sig_id, channel->remote_cid, 0, 4, &config_options);
470 
471     // printf("new state %u\n", channel->state);
472 }
473 
474 void l2cap_decline_connection_internal(uint16_t local_cid, uint8_t reason){
475     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid( local_cid);
476     if (!channel) {
477         fprintf(stderr, "l2cap_decline_connection_internal called but local_cid 0x%x not found", local_cid);
478         return;
479     }
480     l2cap_send_signaling_packet(channel->handle, CONNECTION_RESPONSE, channel->sig_id, 0, 0, reason, 0);
481 
482     // discard channel
483     linked_list_remove(&l2cap_channels, (linked_item_t *) channel);
484     free (channel);
485 }
486 
487 void l2cap_signaling_handle_configure_request(l2cap_channel_t *channel, uint8_t *command){
488     // accept the other's configuration options
489     uint16_t end_pos = 4 + READ_BT_16(command, L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
490     uint16_t pos     = 8;
491     while (pos < end_pos){
492         uint8_t type   = command[pos++];
493         uint8_t length = command[pos++];
494         // MTU { type(8): 1, len(8):2, MTU(16) }
495         if ((type & 0x7f) == 1 && length == 2){
496             channel->remote_mtu = READ_BT_16(command, pos);
497             // printf("l2cap cid %u, remote mtu %u\n", channel->local_cid, channel->remote_mtu);
498         }
499         pos += length;
500     }
501     uint8_t identifier = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
502     // send back received options
503     // l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, identifier, channel->remote_cid, 0, 0, len-4, &command[8]);
504     // send back OK
505     l2cap_send_signaling_packet(channel->handle, CONFIGURE_RESPONSE, identifier, channel->remote_cid, 0, 0, 0, NULL);
506 }
507 
508 void l2cap_signaling_handler_channel(l2cap_channel_t *channel, uint8_t *command){
509 
510     uint8_t code       = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
511     uint8_t identifier = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
512     uint16_t result = 0;
513 
514     // printf("signaling handler code %u\n", code);
515 
516     switch (channel->state) {
517 
518         case L2CAP_STATE_WAIT_CONNECT_RSP:
519             switch (code){
520                 case CONNECTION_RESPONSE:
521                     result = READ_BT_16 (command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+4);
522                     switch (result) {
523                         case 0:
524                             // successful connection
525                             channel->remote_cid = READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
526                             channel->sig_id = l2cap_next_sig_id();
527                             l2cap_send_signaling_packet(channel->handle, CONFIGURE_REQUEST, channel->sig_id, channel->remote_cid, 0, 4, &config_options);
528                             channel->state = L2CAP_STATE_WAIT_CONFIG_REQ_RSP_OR_CONFIG_REQ;
529                             break;
530                         case 1:
531                             // connection pending. get some coffee
532                             break;
533                         default:
534                             // map l2cap connection response result to BTstack status enumeration
535                             l2cap_emit_channel_opened(channel, L2CAP_CONNECTION_RESPONSE_RESULT_SUCCESSFUL + result);
536                             break;
537                     }
538                     break;
539 
540                 case DISCONNECTION_REQUEST:
541                     l2cap_handle_disconnect_request(channel, identifier);
542                     break;
543 
544                 default:
545                     //@TODO: implement other signaling packets
546                     break;
547             }
548             break;
549 
550         case L2CAP_STATE_WAIT_CONFIG_REQ_RSP_OR_CONFIG_REQ:
551             switch (code) {
552                 case CONFIGURE_RESPONSE:
553                     channel->state = L2CAP_STATE_WAIT_CONFIG_REQ;
554                     break;
555                 case CONFIGURE_REQUEST:
556                     l2cap_signaling_handle_configure_request(channel, command);
557                     channel->state = L2CAP_STATE_WAIT_CONFIG_REQ_RSP;
558                     break;
559                 case DISCONNECTION_REQUEST:
560                     l2cap_handle_disconnect_request(channel, identifier);
561                     break;
562                 default:
563                     //@TODO: implement other signaling packets
564                     break;
565             }
566             break;
567 
568         case L2CAP_STATE_WAIT_CONFIG_REQ:
569             switch (code) {
570                 case CONFIGURE_REQUEST:
571                     l2cap_signaling_handle_configure_request(channel, command);
572                     channel->state = L2CAP_STATE_OPEN;
573                     l2cap_emit_channel_opened(channel, 0);  // success
574                     l2cap_emit_credits(channel, 1);
575                     break;
576                 case DISCONNECTION_REQUEST:
577                     l2cap_handle_disconnect_request(channel, identifier);
578                     break;
579                 default:
580                     //@TODO: implement other signaling packets
581                     break;
582             }
583             break;
584 
585         case L2CAP_STATE_WAIT_CONFIG_REQ_RSP:
586             switch (code) {
587                 case CONFIGURE_RESPONSE:
588                     channel->state = L2CAP_STATE_OPEN;
589                     l2cap_emit_channel_opened(channel, 0);  // success
590                     l2cap_emit_credits(channel, 1);
591                     break;
592                 case DISCONNECTION_REQUEST:
593                     l2cap_handle_disconnect_request(channel, identifier);
594                     break;
595                 default:
596                     //@TODO: implement other signaling packets
597                     break;
598             }
599             break;
600 
601         case L2CAP_STATE_WAIT_DISCONNECT:
602             switch (code) {
603                 case DISCONNECTION_RESPONSE:
604                     l2cap_finialize_channel_close(channel);
605                     break;
606                 case DISCONNECTION_REQUEST:
607                     l2cap_handle_disconnect_request(channel, identifier);
608                     break;
609                 default:
610                     //@TODO: implement other signaling packets
611                     break;
612             }
613             break;
614 
615         case L2CAP_STATE_CLOSED:
616             // @TODO handle incoming requests
617             break;
618 
619         case L2CAP_STATE_OPEN:
620             switch (code) {
621                 case DISCONNECTION_REQUEST:
622                     l2cap_handle_disconnect_request(channel, identifier);
623                     break;
624                 default:
625                     //@TODO: implement other signaling packets, e.g. re-configure
626                     break;
627             }
628             break;
629         default:
630             break;
631     }
632     // printf("new state %u\n", channel->state);
633 }
634 
635 
636 void l2cap_signaling_handler_dispatch( hci_con_handle_t handle, uint8_t * command){
637 
638     // get code, signalind identifier and command len
639     uint8_t code   = command[L2CAP_SIGNALING_COMMAND_CODE_OFFSET];
640     uint8_t sig_id = command[L2CAP_SIGNALING_COMMAND_SIGID_OFFSET];
641     uint16_t len   = READ_BT_16(command, L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
642 
643     // not for a particular channel, and not CONNECTION_REQUEST, ECHO_[REQUEST|RESPONSE], INFORMATION_REQUEST
644     if (code < 1 || code == ECHO_RESPONSE || code > INFORMATION_REQUEST){
645         return;
646     }
647 
648     // general commands without an assigned channel
649     switch(code) {
650 
651         case CONNECTION_REQUEST: {
652             uint16_t psm =        READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
653             uint16_t source_cid = READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET+2);
654             l2cap_handle_connection_request(handle, sig_id, psm, source_cid);
655             break;
656         }
657 
658         case ECHO_REQUEST: {
659             // send back packet
660             l2cap_send_signaling_packet(handle, ECHO_RESPONSE, sig_id, len, &command[L2CAP_SIGNALING_COMMAND_DATA_OFFSET]);
661             break;
662         }
663 
664         case INFORMATION_REQUEST: {
665             // we neither support connectionless L2CAP data nor support any flow control modes yet
666             uint16_t infoType = READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
667             if (infoType == 2) {
668                 uint32_t features = 0;
669                 // extended features request supported, however no features present
670                 l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 0, 4, &features);
671             } else {
672                 // all other types are not supported
673                 l2cap_send_signaling_packet(handle, INFORMATION_RESPONSE, sig_id, infoType, 1, 0, NULL);
674             }
675             break;;
676         }
677 
678         default:
679             break;
680     }
681 
682 
683     // Get potential destination CID
684     uint16_t dest_cid = READ_BT_16(command, L2CAP_SIGNALING_COMMAND_DATA_OFFSET);
685 
686     // Find channel for this sig_id and connection handle
687     linked_item_t *it;
688     for (it = (linked_item_t *) l2cap_channels; it ; it = it->next){
689         l2cap_channel_t * channel = (l2cap_channel_t *) it;
690         if (channel->handle == handle) {
691             if (code & 1) {
692                 // match odd commands by previous signaling identifier
693                 if (channel->sig_id == sig_id) {
694                     l2cap_signaling_handler_channel(channel, command);
695                 }
696             } else {
697                 // match even commands by local channel id
698                 if (channel->local_cid == dest_cid) {
699                     l2cap_signaling_handler_channel(channel, command);
700                 }
701             }
702         }
703     }
704 }
705 
706 void l2cap_acl_handler( uint8_t *packet, uint16_t size ){
707 
708     // Get Channel ID
709     uint16_t channel_id = READ_L2CAP_CHANNEL_ID(packet);
710 
711     // Signaling Packet?
712     if (channel_id == 1) {
713 
714         // Get Connection
715         hci_con_handle_t handle = READ_ACL_CONNECTION_HANDLE(packet);
716 
717         uint16_t command_offset = 8;
718         while (command_offset < size) {
719 
720             // handle signaling commands
721             l2cap_signaling_handler_dispatch(handle, &packet[command_offset]);
722 
723             // increment command_offset
724             command_offset += L2CAP_SIGNALING_COMMAND_DATA_OFFSET + READ_BT_16(packet, command_offset + L2CAP_SIGNALING_COMMAND_LENGTH_OFFSET);
725         }
726         return;
727     }
728 
729     // Find channel for this channel_id and connection handle
730     l2cap_channel_t * channel = l2cap_get_channel_for_local_cid(channel_id);
731     if (channel) {
732         l2cap_dispatch(channel, L2CAP_DATA_PACKET, &packet[COMPLETE_L2CAP_HEADER], size-COMPLETE_L2CAP_HEADER);
733     }
734 }
735 
736 static void l2cap_packet_handler(uint8_t packet_type, uint8_t *packet, uint16_t size){
737     switch (packet_type) {
738         case HCI_EVENT_PACKET:
739             l2cap_event_handler(packet, size);
740             break;
741         case HCI_ACL_DATA_PACKET:
742             l2cap_acl_handler(packet, size);
743             break;
744         default:
745             break;
746     }
747 }
748 
749 // finalize closed channel
750 void l2cap_finialize_channel_close(l2cap_channel_t *channel){
751     channel->state = L2CAP_STATE_CLOSED;
752     l2cap_emit_channel_closed(channel);
753 
754     // discard channel
755     linked_list_remove(&l2cap_channels, (linked_item_t *) channel);
756     free (channel);
757 }
758 
759 l2cap_service_t * l2cap_get_service(uint16_t psm){
760     linked_item_t *it;
761 
762     // close open channels
763     for (it = (linked_item_t *) l2cap_services; it ; it = it->next){
764         l2cap_service_t * service = ((l2cap_service_t *) it);
765         if ( service->psm == psm){
766             return service;
767         };
768     }
769     return NULL;
770 }
771 
772 void l2cap_register_service_internal(void *connection, btstack_packet_handler_t packet_handler, uint16_t psm, uint16_t mtu){
773     // check for alread registered psm // TODO: emit error event
774     l2cap_service_t *service = l2cap_get_service(psm);
775     if (service) return;
776 
777     // alloc structure     // TODO: emit error event
778     service = malloc(sizeof(l2cap_service_t));
779     if (!service) return;
780 
781     // fill in
782     service->psm = psm;
783     service->mtu = mtu;
784     service->connection = connection;
785     service->packet_handler = packet_handler;
786 
787     // add to services list
788     linked_list_add(&l2cap_services, (linked_item_t *) service);
789 }
790 
791 void l2cap_unregister_service_internal(void *connection, uint16_t psm){
792     l2cap_service_t *service = l2cap_get_service(psm);
793     if (!service) return;
794     linked_list_remove(&l2cap_services, (linked_item_t *) service);
795     free(service);
796 }
797 
798 //
799 void l2cap_close_connection(void *connection){
800     linked_item_t *it;
801 
802     // close open channels
803     l2cap_channel_t * channel;
804     for (it = (linked_item_t *) l2cap_channels; it ; it = it->next){
805         channel = (l2cap_channel_t *) it;
806         if (channel->connection == connection) {
807             channel->sig_id = l2cap_next_sig_id();
808             l2cap_send_signaling_packet( channel->handle, DISCONNECTION_REQUEST, channel->sig_id, channel->remote_cid, channel->local_cid);
809             channel->state = L2CAP_STATE_WAIT_DISCONNECT;
810         }
811     }
812 
813     // unregister services
814     it = (linked_item_t *) &l2cap_services;
815     while (it->next){
816         l2cap_service_t * service = (l2cap_service_t *) it->next;
817         if (service->connection == connection){
818             it->next = it->next->next;
819             free(service);
820         } else {
821             it = it->next;
822         }
823     }
824 }
825