xref: /btstack/src/hci.c (revision 3144bce463fab82477d6421cb1a5ef05e01df63d)
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  *  hci.c
34  *
35  *  Created by Matthias Ringwald on 4/29/09.
36  *
37  */
38 
39 #include "hci.h"
40 
41 #include <unistd.h>
42 #include <stdarg.h>
43 #include <string.h>
44 #include <stdio.h>
45 
46 #include "debug.h"
47 #include "hci_dump.h"
48 
49 #include "../include/btstack/hci_cmds.h"
50 #include "../include/btstack/version.h"
51 
52 // temp
53 #include "l2cap.h"
54 
55 #define HCI_CONNECTION_TIMEOUT_MS 10000
56 
57 // the STACK is here
58 static hci_stack_t       hci_stack;
59 
60 /**
61  * get connection for a given handle
62  *
63  * @return connection OR NULL, if not found
64  */
65 hci_connection_t * connection_for_handle(hci_con_handle_t con_handle){
66     linked_item_t *it;
67     for (it = (linked_item_t *) hci_stack.connections; it ; it = it->next){
68         if ( ((hci_connection_t *) it)->con_handle == con_handle){
69             return (hci_connection_t *) it;
70         }
71     }
72     return NULL;
73 }
74 
75 static void hci_connection_timeout_handler(timer_source_t *timer){
76     hci_connection_t * connection = linked_item_get_user(&timer->item);
77     struct timeval tv;
78     gettimeofday(&tv, NULL);
79     if (tv.tv_sec >= connection->timestamp.tv_sec + HCI_CONNECTION_TIMEOUT_MS/1000) {
80         // connections might be timed out
81         hci_emit_l2cap_check_timeout(connection);
82         run_loop_set_timer(timer, HCI_CONNECTION_TIMEOUT_MS);
83     } else {
84         // next timeout check at
85         timer->timeout.tv_sec = connection->timestamp.tv_sec + HCI_CONNECTION_TIMEOUT_MS/1000;
86     }
87     run_loop_add_timer(timer);
88 }
89 
90 static void hci_connection_timestamp(hci_connection_t *connection){
91     gettimeofday(&connection->timestamp, NULL);
92 }
93 
94 /**
95  * create connection for given address
96  *
97  * @return connection OR NULL, if not found
98  */
99 static hci_connection_t * create_connection_for_addr(bd_addr_t addr){
100     hci_connection_t * conn = malloc( sizeof(hci_connection_t) );
101     if (!conn) return NULL;
102     BD_ADDR_COPY(conn->address, addr);
103     conn->con_handle = 0xffff;
104     conn->authentication_flags = 0;
105     linked_item_set_user(&conn->timeout.item, conn);
106     conn->timeout.process = hci_connection_timeout_handler;
107     hci_connection_timestamp(conn);
108     conn->acl_recombination_length = 0;
109     conn->acl_recombination_pos = 0;
110     conn->num_acl_packets_sent = 0;
111     linked_list_add(&hci_stack.connections, (linked_item_t *) conn);
112     return conn;
113 }
114 
115 /**
116  * get connection for given address
117  *
118  * @return connection OR NULL, if not found
119  */
120 static hci_connection_t * connection_for_address(bd_addr_t address){
121     linked_item_t *it;
122     for (it = (linked_item_t *) hci_stack.connections; it ; it = it->next){
123         if ( ! BD_ADDR_CMP( ((hci_connection_t *) it)->address, address) ){
124             return (hci_connection_t *) it;
125         }
126     }
127     return NULL;
128 }
129 
130 /**
131  * add authentication flags and reset timer
132  */
133 static void hci_add_connection_flags_for_flipped_bd_addr(uint8_t *bd_addr, hci_authentication_flags_t flags){
134     bd_addr_t addr;
135     bt_flip_addr(addr, *(bd_addr_t *) bd_addr);
136     hci_connection_t * conn = connection_for_address(addr);
137     if (conn) {
138         conn->authentication_flags |= flags;
139         hci_connection_timestamp(conn);
140     }
141 }
142 
143 int  hci_authentication_active_for_handle(hci_con_handle_t handle){
144     hci_connection_t * conn = connection_for_handle(handle);
145     if (!conn) return 0;
146     if (!conn->authentication_flags) return 0;
147     if (conn->authentication_flags & SENT_LINK_KEY_REPLY) return 0;
148     if (conn->authentication_flags & RECV_LINK_KEY_NOTIFICATION) return 0;
149     return 1;
150 }
151 
152 void hci_drop_link_key_for_bd_addr(bd_addr_t *addr){
153     if (hci_stack.remote_device_db) {
154         hci_stack.remote_device_db->delete_link_key(addr);
155     }
156 }
157 
158 
159 /**
160  * count connections
161  */
162 static int nr_hci_connections(){
163     int count = 0;
164     linked_item_t *it;
165     for (it = (linked_item_t *) hci_stack.connections; it ; it = it->next, count++);
166     return count;
167 }
168 
169 /**
170  * Dummy handler called by HCI
171  */
172 static void dummy_handler(uint8_t packet_type, uint8_t *packet, uint16_t size){
173 }
174 
175 uint8_t hci_number_outgoing_packets(hci_con_handle_t handle){
176     hci_connection_t * connection = connection_for_handle(handle);
177     if (!connection) {
178         log_err("hci_number_outgoing_packets connectino for handle %u does not exist!\n", handle);
179         return 0;
180     }
181     return connection->num_acl_packets_sent;
182 }
183 
184 uint8_t hci_number_free_acl_slots(){
185     uint8_t free_slots = hci_stack.total_num_acl_packets;
186     linked_item_t *it;
187     for (it = (linked_item_t *) hci_stack.connections; it ; it = it->next){
188         hci_connection_t * connection = (hci_connection_t *) it;
189         if (free_slots < connection->num_acl_packets_sent) {
190             log_err("hci_number_free_acl_slots: sum of outgoing packets > total acl packets!\n");
191             return 0;
192         }
193         free_slots -= connection->num_acl_packets_sent;
194     }
195     return free_slots;
196 }
197 
198 uint16_t hci_max_acl_data_packet_length(){
199     return hci_stack.acl_data_packet_length;
200 }
201 
202 int hci_ready_to_send(hci_con_handle_t handle){
203     return hci_number_free_acl_slots() && hci_number_outgoing_packets(handle) < 2;
204 }
205 
206 int hci_send_acl_packet(uint8_t *packet, int size){
207 
208     // check for free places on BT module
209     if (!hci_number_free_acl_slots()) return -1;
210 
211     hci_con_handle_t con_handle = READ_ACL_CONNECTION_HANDLE(packet);
212     hci_connection_t *connection = connection_for_handle( con_handle);
213     if (!connection) return 0;
214     hci_connection_timestamp(connection);
215 
216     // count packet
217     connection->num_acl_packets_sent++;
218     // log_dbg("hci_send_acl_packet - handle %u, sent %u\n", connection->con_handle, connection->num_acl_packets_sent);
219 
220     // send packet - ignore errors
221     hci_stack.hci_transport->send_packet(HCI_ACL_DATA_PACKET, packet, size);
222 
223     return 0;
224 }
225 
226 static void acl_handler(uint8_t *packet, int size){
227 
228     // get info
229     hci_con_handle_t con_handle = READ_ACL_CONNECTION_HANDLE(packet);
230     hci_connection_t *conn      = connection_for_handle(con_handle);
231     uint8_t  acl_flags          = READ_ACL_FLAGS(packet);
232     uint16_t acl_length         = READ_ACL_LENGTH(packet);
233 
234     // ignore non-registered handle
235     if (!conn){
236         log_err( "hci.c: acl_handler called with non-registered handle %u!\n" , con_handle);
237         return;
238     }
239 
240     // update idle timestamp
241     hci_connection_timestamp(conn);
242 
243     // handle different packet types
244     switch (acl_flags & 0x03) {
245 
246         case 0x01: // continuation fragment
247 
248             // sanity check
249             if (conn->acl_recombination_pos == 0) {
250                 log_err( "ACL Cont Fragment but no first fragment for handle 0x%02x\n", con_handle);
251                 return;
252             }
253 
254             // append fragment payload (header already stored)
255             memcpy(&conn->acl_recombination_buffer[conn->acl_recombination_pos], &packet[4], acl_length );
256             conn->acl_recombination_pos += acl_length;
257 
258             // log_err( "ACL Cont Fragment: acl_len %u, combined_len %u, l2cap_len %u\n",
259             //        acl_length, connection->acl_recombination_pos, connection->acl_recombination_length);
260 
261             // forward complete L2CAP packet if complete.
262             if (conn->acl_recombination_pos >= conn->acl_recombination_length + 4 + 4){ // pos already incl. ACL header
263 
264                 hci_stack.packet_handler(HCI_ACL_DATA_PACKET, conn->acl_recombination_buffer, conn->acl_recombination_pos);
265                 // reset recombination buffer
266                 conn->acl_recombination_length = 0;
267                 conn->acl_recombination_pos = 0;
268             }
269             break;
270 
271         case 0x02: { // first fragment
272 
273             // sanity check
274             if (conn->acl_recombination_pos) {
275                 log_err( "ACL First Fragment but data in buffer for handle 0x%02x\n", con_handle);
276                 return;
277             }
278 
279             // peek into L2CAP packet!
280             uint16_t l2cap_length = READ_L2CAP_LENGTH( packet );
281 
282             // compare fragment size to L2CAP packet size
283             if (acl_length >= l2cap_length + 4){
284 
285                 // forward fragment as L2CAP packet
286                 hci_stack.packet_handler(HCI_ACL_DATA_PACKET, packet, acl_length + 4);
287 
288             } else {
289                 // store first fragment and tweak acl length for complete package
290                 memcpy(conn->acl_recombination_buffer, packet, acl_length + 4);
291                 conn->acl_recombination_pos    = acl_length + 4;
292                 conn->acl_recombination_length = l2cap_length;
293                 bt_store_16(conn->acl_recombination_buffer, 2, acl_length +4);
294                 // log_err( "ACL First Fragment: acl_len %u, l2cap_len %u\n", acl_length, l2cap_length);
295             }
296             break;
297 
298         }
299         default:
300             log_err( "hci.c: acl_handler called with invalid packet boundary flags %u\n", acl_flags & 0x03);
301             return;
302     }
303 
304     // execute main loop
305     hci_run();
306 }
307 
308 static hci_shutdown_connection(hci_connection_t *conn){
309     log_dbg("Connection closed: handle %u, ", conn->con_handle);
310     print_bd_addr( conn->address );
311     log_dbg("\n");
312     run_loop_remove_timer(&conn->timeout);
313     linked_list_remove(&hci_stack.connections, (linked_item_t *) conn);
314     free( conn );
315     hci_emit_nr_connections_changed();
316 }
317 
318 // avoid huge local variables
319 static device_name_t device_name;
320 static void event_handler(uint8_t *packet, int size){
321     bd_addr_t addr;
322     hci_con_handle_t handle;
323     hci_connection_t * conn;
324     int i;
325     link_key_t link_key;
326 
327     // get num_cmd_packets
328     if (packet[0] == HCI_EVENT_COMMAND_COMPLETE || packet[0] == HCI_EVENT_COMMAND_STATUS){
329         // Get Num_HCI_Command_Packets
330         hci_stack.num_cmd_packets = packet[2];
331     }
332 
333     switch (packet[0]) {
334 
335         case HCI_EVENT_COMMAND_COMPLETE:
336             if (COMMAND_COMPLETE_EVENT(packet, hci_read_buffer_size)){
337                 // from offset 5
338                 // status
339                 hci_stack.acl_data_packet_length = READ_BT_16(packet, 6);
340                 // ignore: SCO data packet len (8)
341                 hci_stack.total_num_acl_packets  = packet[9];
342                 // ignore: total num SCO packets
343                 if (hci_stack.state == HCI_STATE_INITIALIZING){
344                     log_dbg("hci_read_buffer_size: size %u, count %u\n", hci_stack.acl_data_packet_length, hci_stack.total_num_acl_packets);
345                 }
346             }
347             break;
348 
349         case HCI_EVENT_NUMBER_OF_COMPLETED_PACKETS:
350             for (i=0; i<packet[2];i++){
351                 handle = READ_BT_16(packet, 3 + 2*i);
352                 uint16_t num_packets = READ_BT_16(packet, 3 + packet[2]*2 + 2*i);
353                 conn = connection_for_handle(handle);
354                 if (!conn){
355                     log_err("hci_number_completed_packet lists unused con handle %u\n", handle);
356                     continue;
357                 }
358                 conn->num_acl_packets_sent -= num_packets;
359                 // log_dbg("hci_number_completed_packet %u processed for handle %u, outstanding %u\n", num_packets, handle, conn->num_acl_packets_sent);
360             }
361             break;
362 
363         case HCI_EVENT_CONNECTION_REQUEST:
364             bt_flip_addr(addr, &packet[2]);
365             // TODO: eval COD 8-10
366             uint8_t link_type = packet[11];
367             log_dbg("Connection_incoming: "); print_bd_addr(addr); log_dbg(", type %u\n", link_type);
368             if (link_type == 1) { // ACL
369                 conn = connection_for_address(addr);
370                 if (!conn) {
371                     conn = create_connection_for_addr(addr);
372                 }
373                 // TODO: check for malloc failure
374                 conn->state = ACCEPTED_CONNECTION_REQUEST;
375                 hci_send_cmd(&hci_accept_connection_request, addr, 1);
376             } else {
377                 // TODO: decline request
378             }
379             break;
380 
381         case HCI_EVENT_CONNECTION_COMPLETE:
382             // Connection management
383             bt_flip_addr(addr, &packet[5]);
384             log_dbg("Connection_complete (status=%u)", packet[2]); print_bd_addr(addr); log_dbg("\n");
385             conn = connection_for_address(addr);
386             if (conn) {
387                 if (!packet[2]){
388                     conn->state = OPEN;
389                     conn->con_handle = READ_BT_16(packet, 3);
390 
391                     gettimeofday(&conn->timestamp, NULL);
392                     run_loop_set_timer(&conn->timeout, HCI_CONNECTION_TIMEOUT_MS);
393                     run_loop_add_timer(&conn->timeout);
394 
395                     log_dbg("New connection: handle %u, ", conn->con_handle);
396                     print_bd_addr( conn->address );
397                     log_dbg("\n");
398 
399                     hci_emit_nr_connections_changed();
400                 } else {
401                     // connection failed, remove entry
402                     linked_list_remove(&hci_stack.connections, (linked_item_t *) conn);
403                     free( conn );
404 
405                     // if authentication error, also delete link key
406                     if (packet[2] == 0x05) {
407                         hci_drop_link_key_for_bd_addr(&addr);
408                     }
409                 }
410             }
411             break;
412 
413         case HCI_EVENT_LINK_KEY_REQUEST:
414             hci_add_connection_flags_for_flipped_bd_addr(&packet[2], RECV_LINK_KEY_REQUEST);
415             if (!hci_stack.remote_device_db) break;
416             bt_flip_addr(addr, &packet[2]);
417             if ( hci_stack.remote_device_db->get_link_key( &addr, &link_key)){
418                 hci_send_cmd(&hci_link_key_request_reply, &addr, &link_key);
419             } else {
420                 hci_send_cmd(&hci_link_key_request_negative_reply, &addr);
421             }
422             // request already answered
423             return;
424 
425         case HCI_EVENT_LINK_KEY_NOTIFICATION:
426             hci_add_connection_flags_for_flipped_bd_addr(&packet[2], RECV_LINK_KEY_NOTIFICATION);
427             if (!hci_stack.remote_device_db) break;
428             bt_flip_addr(addr, &packet[2]);
429             hci_stack.remote_device_db->put_link_key(&addr, (link_key_t *) &packet[8]);
430             // still forward event to allow dismiss of pairing dialog
431             break;
432 
433         case HCI_EVENT_PIN_CODE_REQUEST:
434             hci_add_connection_flags_for_flipped_bd_addr(&packet[2], RECV_PIN_CODE_REQUEST);
435             break;
436 
437         case HCI_EVENT_REMOTE_NAME_REQUEST_COMPLETE:
438             if (!hci_stack.remote_device_db) break;
439             if (packet[2]) break; // status not ok
440             bt_flip_addr(addr, &packet[3]);
441             bzero(&device_name, sizeof(device_name_t));
442             strncpy((char*) device_name, (char*) &packet[9], 248);
443             hci_stack.remote_device_db->put_name(&addr, &device_name);
444             break;
445 
446         case HCI_EVENT_INQUIRY_RESULT:
447         case HCI_EVENT_INQUIRY_RESULT_WITH_RSSI:
448             if (!hci_stack.remote_device_db) break;
449             // first send inq result packet
450             hci_stack.packet_handler(HCI_EVENT_PACKET, packet, size);
451             // then send cached remote names
452             for (i=0; i<packet[2];i++){
453                 bt_flip_addr(addr, &packet[3+i*6]);
454                 if (hci_stack.remote_device_db->get_name(&addr, &device_name)){
455                     hci_emit_remote_name_cached(&addr, &device_name);
456                 }
457             }
458             return;
459 
460         case HCI_EVENT_DISCONNECTION_COMPLETE:
461             if (!packet[2]){
462                 handle = READ_BT_16(packet, 3);
463                 hci_connection_t * conn = connection_for_handle(handle);
464                 if (conn) {
465                     hci_shutdown_connection(conn);
466                 }
467             }
468             break;
469 
470         default:
471             break;
472     }
473 
474     // handle BT initialization
475     if (hci_stack.state == HCI_STATE_INITIALIZING){
476         // handle H4 synchronization loss on restart
477         // if (hci_stack.substate == 1 && packet[0] == HCI_EVENT_HARDWARE_ERROR){
478         //    hci_stack.substate = 0;
479         // }
480         // handle normal init sequence
481         if (hci_stack.substate % 2){
482             // odd: waiting for event
483             if (packet[0] == HCI_EVENT_COMMAND_COMPLETE){
484                 hci_stack.substate++;
485             }
486         }
487     }
488 
489     hci_stack.packet_handler(HCI_EVENT_PACKET, packet, size);
490 
491 	// execute main loop
492 	hci_run();
493 }
494 
495 void packet_handler(uint8_t packet_type, uint8_t *packet, uint16_t size){
496     switch (packet_type) {
497         case HCI_EVENT_PACKET:
498             event_handler(packet, size);
499             break;
500         case HCI_ACL_DATA_PACKET:
501             acl_handler(packet, size);
502             break;
503         default:
504             break;
505     }
506 }
507 
508 /** Register HCI packet handlers */
509 void hci_register_packet_handler(void (*handler)(uint8_t packet_type, uint8_t *packet, uint16_t size)){
510     hci_stack.packet_handler = handler;
511 }
512 
513 void hci_init(hci_transport_t *transport, void *config, bt_control_t *control, remote_device_db_t * remote_device_db){
514 
515     // reference to use transport layer implementation
516     hci_stack.hci_transport = transport;
517 
518     // references to used control implementation
519     hci_stack.control = control;
520 
521     // reference to used config
522     hci_stack.config = config;
523 
524     // no connections yet
525     hci_stack.connections = NULL;
526 
527     // empty cmd buffer
528     hci_stack.hci_cmd_buffer = malloc(3+255);
529 
530     // higher level handler
531     hci_stack.packet_handler = dummy_handler;
532 
533     // store and open remote device db
534     hci_stack.remote_device_db = remote_device_db;
535     if (hci_stack.remote_device_db) {
536         hci_stack.remote_device_db->open();
537     }
538 
539     // register packet handlers with transport
540     transport->register_packet_handler(&packet_handler);
541 }
542 
543 void hci_close(){
544     // close remote device db
545     if (hci_stack.remote_device_db) {
546         hci_stack.remote_device_db->close();
547     }
548 }
549 
550 // State-Module-Driver overview
551 // state                    module  low-level
552 // HCI_STATE_OFF             off      close
553 // HCI_STATE_INITIALIZING,   on       open
554 // HCI_STATE_WORKING,        on       open
555 // HCI_STATE_HALTING,        on       open
556 // HCI_STATE_SLEEPING,    off/sleep   close
557 // HCI_STATE_FALLING_ASLEEP  on       open
558 
559 static int hci_power_control_on(){
560 
561     // power on
562     int err = 0;
563     if (hci_stack.control && hci_stack.control->on){
564         err = (*hci_stack.control->on)(hci_stack.config);
565     }
566     if (err){
567         log_err( "POWER_ON failed\n");
568         hci_emit_hci_open_failed();
569         return err;
570     }
571 
572     // open low-level device
573     err = hci_stack.hci_transport->open(hci_stack.config);
574     if (err){
575         log_err( "HCI_INIT failed, turning Bluetooth off again\n");
576         if (hci_stack.control && hci_stack.control->off){
577             (*hci_stack.control->off)(hci_stack.config);
578         }
579         hci_emit_hci_open_failed();
580         return err;
581     }
582     return 0;
583 }
584 
585 static int hci_power_control_wake(){
586 
587     log_dbg("hci_power_control_wake");
588 
589     // wake on
590     int err = 0;
591     if (hci_stack.control && hci_stack.control->wake){
592         err = (*hci_stack.control->wake)(hci_stack.config);
593     }
594     if (err){
595         log_err( "WAKE_ON failed\n");
596         hci_emit_hci_open_failed();
597         return err;
598     }
599 
600     // open low-level device
601     err = hci_stack.hci_transport->open(hci_stack.config);
602     if (err){
603         log_err( "HCI_INIT failed, turning Bluetooth off again\n");
604         if (hci_stack.control && hci_stack.control->off){
605             (*hci_stack.control->off)(hci_stack.config);
606         }
607         hci_emit_hci_open_failed();
608         return err;
609     }
610     return 0;
611 }
612 
613 static void hci_power_control_off(){
614 
615     // close low-level device
616     hci_stack.hci_transport->close(hci_stack.config);
617 
618     // power off
619     if (hci_stack.control && hci_stack.control->off){
620         (*hci_stack.control->off)(hci_stack.config);
621     }
622     hci_stack.state = HCI_STATE_OFF;
623 }
624 
625 static void hci_power_control_sleep(){
626 
627     log_dbg("hci_power_control_sleep");
628 
629     // close low-level device
630     hci_stack.hci_transport->close(hci_stack.config);
631 
632     // sleep mode
633     if (hci_stack.control && hci_stack.control->sleep){
634         (*hci_stack.control->sleep)(hci_stack.config);
635     }
636     hci_stack.state = HCI_STATE_SLEEPING;
637 }
638 
639 int hci_power_control(HCI_POWER_MODE power_mode){
640 
641     log_dbg("hci_power_control: %u\n", power_mode);
642 
643     int err = 0;
644     switch (hci_stack.state){
645 
646         case HCI_STATE_OFF:
647             switch (power_mode){
648                 case HCI_POWER_ON:
649                     err = hci_power_control_on();
650                     if (err) return err;
651                     // set up state machine
652                     hci_stack.num_cmd_packets = 1; // assume that one cmd can be sent
653                     hci_stack.state = HCI_STATE_INITIALIZING;
654                     hci_stack.substate = 0;
655                     break;
656                 case HCI_POWER_OFF:
657                     // do nothing
658                     break;
659                 case HCI_POWER_SLEEP:
660                     // do nothing (with SLEEP == OFF)
661                     break;
662             }
663             break;
664 
665         case HCI_STATE_INITIALIZING:
666             switch (power_mode){
667                 case HCI_POWER_ON:
668                     // do nothing
669                     break;
670                 case HCI_POWER_OFF:
671                     // no connections yet, just turn it off
672                     hci_power_control_off();
673                     break;
674                 case HCI_POWER_SLEEP:
675                     // no connections yet, just turn it off
676                     hci_power_control_sleep();
677                     break;
678             }
679             break;
680 
681         case HCI_STATE_WORKING:
682             switch (power_mode){
683                 case HCI_POWER_ON:
684                     // do nothing
685                     break;
686                 case HCI_POWER_OFF:
687                     // see hci_run
688                     hci_stack.state = HCI_STATE_HALTING;
689                     break;
690                 case HCI_POWER_SLEEP:
691                     // see hci_run
692                     hci_stack.state = HCI_STATE_FALLING_ASLEEP;
693                     break;
694             }
695             break;
696 
697         case HCI_STATE_HALTING:
698             switch (power_mode){
699                 case HCI_POWER_ON:
700                     // set up state machine
701                     hci_stack.state = HCI_STATE_INITIALIZING;
702                     hci_stack.substate = 0;
703                     break;
704                 case HCI_POWER_OFF:
705                     // do nothing
706                     break;
707                 case HCI_POWER_SLEEP:
708                     // see hci_run
709                     hci_stack.state = HCI_STATE_FALLING_ASLEEP;
710                     break;
711             }
712             break;
713 
714         case HCI_STATE_FALLING_ASLEEP:
715             switch (power_mode){
716                 case HCI_POWER_ON:
717                     // set up state machine
718                     hci_stack.num_cmd_packets = 1; // assume that one cmd can be sent
719                     hci_stack.state = HCI_STATE_INITIALIZING;
720                     hci_stack.substate = 0;
721                     break;
722                 case HCI_POWER_OFF:
723                     // see hci_run
724                     hci_stack.state = HCI_STATE_HALTING;
725                     break;
726                 case HCI_POWER_SLEEP:
727                     // do nothing
728                     break;
729             }
730             break;
731 
732         case HCI_STATE_SLEEPING:
733             switch (power_mode){
734                 case HCI_POWER_ON:
735                     err = hci_power_control_wake();
736                     if (err) return err;
737                     // set up state machine
738                     hci_stack.num_cmd_packets = 1; // assume that one cmd can be sent
739                     hci_stack.state = HCI_STATE_INITIALIZING;
740                     hci_stack.substate = 0;
741                     break;
742                 case HCI_POWER_OFF:
743                     hci_stack.state = HCI_STATE_OFF;
744                     break;
745                 case HCI_POWER_SLEEP:
746                     // do nothing
747                     break;
748             }
749             break;
750     }
751 
752     // create internal event
753 	hci_emit_state();
754 
755 	// trigger next/first action
756 	hci_run();
757 
758     return 0;
759 }
760 
761 void hci_run(){
762 
763     if (hci_stack.num_cmd_packets == 0) {
764         // cannot send command yet
765         return;
766     }
767 
768     hci_connection_t * connection;
769 
770     switch (hci_stack.state){
771         case HCI_STATE_INITIALIZING:
772             if (hci_stack.substate % 2) {
773                 // odd: waiting for command completion
774                 return;
775             }
776             switch (hci_stack.substate >> 1){
777                 case 0:
778                     hci_send_cmd(&hci_reset);
779                     break;
780                 case 1:
781                     // custom initialization
782                     if (hci_stack.control && hci_stack.control->next_command){
783                         uint8_t * cmd = (*hci_stack.control->next_command)(hci_stack.config);
784                         if (cmd) {
785                             int size = 3 + cmd[2];
786                             hci_stack.hci_transport->send_packet(HCI_COMMAND_DATA_PACKET, cmd, size);
787                             hci_stack.substate = 0; // more init commands
788                             break;
789                         }
790                     }
791                     // otherwise continue
792 					hci_send_cmd(&hci_read_bd_addr);
793 					break;
794 				case 2:
795 					hci_send_cmd(&hci_read_buffer_size);
796 					break;
797                 case 3:
798                     // ca. 15 sec
799                     hci_send_cmd(&hci_write_page_timeout, 0x6000);
800                     break;
801 				case 4:
802 					hci_send_cmd(&hci_write_scan_enable, 3); // 3 inq scan + page scan
803 					break;
804                 case 5:
805 #ifndef EMBEDDED
806                 {
807                     char hostname[30];
808                     gethostname(hostname, 30);
809                     hostname[29] = '\0';
810                     hci_send_cmd(&hci_write_local_name, hostname);
811                     break;
812                 }
813                 case 6:
814 #endif
815                     // done.
816                     hci_stack.state = HCI_STATE_WORKING;
817                     hci_emit_state();
818                     break;
819                 default:
820                     break;
821             }
822             hci_stack.substate++;
823             break;
824 
825         case HCI_STATE_HALTING:
826 
827             log_dbg("HCI_STATE_HALTING\n");
828             // close all open connections
829             connection =  (hci_connection_t *) hci_stack.connections;
830             if (connection){
831                 log_dbg("HCI_STATE_HALTING, connection %u, handle %u\n", (int) connection, connection->con_handle);
832                 // send disconnect
833                 bt_send_cmd(&hci_disconnect, connection->con_handle, 0x13);  // remote closed connection
834 
835                 // send disconnected event right away - causes higher layer connections to get closed, too.
836                 hci_shutdown_connection(connection);
837 
838                 // remove from table
839                 hci_stack.connections = connection->item.next;
840                 return;
841             }
842             log_dbg("HCI_STATE_HALTING, calling off\n");
843 
844             // switch mode
845             hci_power_control_off();
846             hci_emit_state();
847             log_dbg("HCI_STATE_HALTING, done\n");
848             break;
849 
850         case HCI_STATE_FALLING_ASLEEP:
851             // close all open connections
852             connection =  (hci_connection_t *) hci_stack.connections;
853             if (connection){
854                 // send disconnect
855                 bt_send_cmd(&hci_disconnect, connection->con_handle, 0x13);  // remote closed connection
856 
857                 // send disconnected event right away - causes higher layer connections to get closed, too.
858                 hci_shutdown_connection(connection);
859 
860                 // remove from table
861                 hci_stack.connections = connection->item.next;
862                 return;
863             }
864 
865             // switch mode
866             hci_power_control_sleep();
867             hci_emit_state();
868             break;
869 
870         default:
871             break;
872     }
873 }
874 
875 int hci_send_cmd_packet(uint8_t *packet, int size){
876     bd_addr_t addr;
877     hci_connection_t * conn;
878     // house-keeping
879 
880     // create_connection?
881     if (IS_COMMAND(packet, hci_create_connection)){
882         bt_flip_addr(addr, &packet[3]);
883         log_dbg("Create_connection to "); print_bd_addr(addr); log_dbg("\n");
884         conn = connection_for_address(addr);
885         if (conn) {
886             // if connection exists
887             if (conn->state == OPEN) {
888                 // if OPEN, emit connection complete command
889                 hci_emit_connection_complete(conn);
890             }
891             //    otherwise, just ignore
892             return 0; // don't sent packet to controller
893 
894         } else{
895             conn = create_connection_for_addr(addr);
896             if (conn){
897                 //    create connection struct and register, state = SENT_CREATE_CONNECTION
898                 conn->state = SENT_CREATE_CONNECTION;
899             }
900         }
901     }
902 
903     if (IS_COMMAND(packet, hci_link_key_request_reply)){
904         hci_add_connection_flags_for_flipped_bd_addr(&packet[3], SENT_LINK_KEY_REPLY);
905     }
906     if (IS_COMMAND(packet, hci_link_key_request_negative_reply)){
907         hci_add_connection_flags_for_flipped_bd_addr(&packet[3], SENT_LINK_KEY_NEGATIVE_REQUEST);
908     }
909     if (IS_COMMAND(packet, hci_pin_code_request_reply)){
910         hci_add_connection_flags_for_flipped_bd_addr(&packet[3], SENT_PIN_CODE_REPLY);
911     }
912     if (IS_COMMAND(packet, hci_pin_code_request_negative_reply)){
913         hci_add_connection_flags_for_flipped_bd_addr(&packet[3], SENT_PIN_CODE_NEGATIVE_REPLY);
914     }
915 
916     if (IS_COMMAND(packet, hci_delete_stored_link_key)){
917         if (hci_stack.remote_device_db){
918             bt_flip_addr(addr, &packet[3]);
919             hci_stack.remote_device_db->delete_link_key(&addr);
920         }
921     }
922 
923     hci_stack.num_cmd_packets--;
924     return hci_stack.hci_transport->send_packet(HCI_COMMAND_DATA_PACKET, packet, size);
925 }
926 
927 /**
928  * pre: numcmds >= 0 - it's allowed to send a command to the controller
929  */
930 int hci_send_cmd(const hci_cmd_t *cmd, ...){
931     va_list argptr;
932     va_start(argptr, cmd);
933     uint8_t * hci_cmd_buffer = hci_stack.hci_cmd_buffer;
934     uint16_t size = hci_create_cmd_internal(hci_stack.hci_cmd_buffer, cmd, argptr);
935     va_end(argptr);
936     return hci_send_cmd_packet(hci_cmd_buffer, size);
937 }
938 
939 // Create various non-HCI events.
940 // TODO: generalize, use table similar to hci_create_command
941 
942 void hci_emit_state(){
943     uint8_t len = 3;
944     uint8_t event[len];
945     event[0] = BTSTACK_EVENT_STATE;
946     event[1] = len - 3;
947     event[2] = hci_stack.state;
948     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
949     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
950 }
951 
952 void hci_emit_connection_complete(hci_connection_t *conn){
953     uint8_t len = 13;
954     uint8_t event[len];
955     event[0] = HCI_EVENT_CONNECTION_COMPLETE;
956     event[1] = len - 3;
957     event[2] = 0; // status = OK
958     bt_store_16(event, 3, conn->con_handle);
959     bt_flip_addr(&event[5], conn->address);
960     event[11] = 1; // ACL connection
961     event[12] = 0; // encryption disabled
962     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
963     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
964 }
965 
966 void hci_emit_l2cap_check_timeout(hci_connection_t *conn){
967     uint8_t len = 4;
968     uint8_t event[len];
969     event[0] = L2CAP_EVENT_TIMEOUT_CHECK;
970     event[1] = len - 2;
971     bt_store_16(event, 2, conn->con_handle);
972     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
973     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
974 }
975 
976 void hci_emit_nr_connections_changed(){
977     uint8_t len = 3;
978     uint8_t event[len];
979     event[0] = BTSTACK_EVENT_NR_CONNECTIONS_CHANGED;
980     event[1] = len - 2;
981     event[2] = nr_hci_connections();
982     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
983     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
984 }
985 
986 void hci_emit_hci_open_failed(){
987     uint8_t len = 2;
988     uint8_t event[len];
989     event[0] = BTSTACK_EVENT_POWERON_FAILED;
990     event[1] = len - 2;
991     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
992     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
993 }
994 
995 
996 void hci_emit_btstack_version() {
997     uint8_t len = 6;
998     uint8_t event[len];
999     event[0] = BTSTACK_EVENT_VERSION;
1000     event[1] = len - 2;
1001     event[len++] = BTSTACK_MAJOR;
1002     event[len++] = BTSTACK_MINOR;
1003     bt_store_16(event, len, BTSTACK_REVISION);
1004     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
1005     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
1006 }
1007 
1008 void hci_emit_system_bluetooth_enabled(uint8_t enabled){
1009     uint8_t len = 3;
1010     uint8_t event[len];
1011     event[0] = BTSTACK_EVENT_SYSTEM_BLUETOOTH_ENABLED;
1012     event[1] = len - 2;
1013     event[2] = enabled;
1014     hci_dump_packet( HCI_EVENT_PACKET, 0, event, len);
1015     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
1016 }
1017 
1018 void hci_emit_remote_name_cached(bd_addr_t *addr, device_name_t *name){
1019     uint16_t len = 2+1+6+248;
1020     uint8_t event[len];
1021     event[0] = BTSTACK_EVENT_REMOTE_NAME_CACHED;
1022     event[1] = len - 2;
1023     event[2] = 0;   // just to be compatible with HCI_EVENT_REMOTE_NAME_REQUEST_COMPLETE
1024     bt_flip_addr(&event[3], *addr);
1025     memcpy(&event[9], name, 248);
1026     hci_dump_packet(HCI_EVENT_PACKET, 0, event, len);
1027     hci_stack.packet_handler(HCI_EVENT_PACKET, event, len);
1028 }
1029