xref: /btstack/src/classic/rfcomm.c (revision 02f83142d437cdf22e03c9e8be9c859cbc17c701)
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  *  rfcomm.c
40  */
41 
42 #include <stdio.h>
43 #include <stdlib.h>
44 #include <string.h> // memcpy
45 #include <stdint.h>
46 
47 #include "hci_cmds.h"
48 #include "utils.h"
49 
50 #include "utils.h"
51 #include "btstack_memory.h"
52 #include "hci.h"
53 #include "hci_dump.h"
54 #include "debug.h"
55 #include "classic/rfcomm.h"
56 
57 // workaround for missing PRIxPTR on mspgcc (16/20-bit MCU)
58 #ifndef PRIxPTR
59 #if defined(__MSP430X__)  &&  defined(__MSP430X_LARGE__)
60 #define PRIxPTR "lx"
61 #else
62 #define PRIxPTR "x"
63 #endif
64 #endif
65 
66 
67 // Control field values      bit no.       1 2 3 4 PF 6 7 8
68 #define BT_RFCOMM_SABM       0x3F       // 1 1 1 1  1 1 0 0
69 #define BT_RFCOMM_UA         0x73       // 1 1 0 0  1 1 1 0
70 #define BT_RFCOMM_DM         0x0F       // 1 1 1 1  0 0 0 0
71 #define BT_RFCOMM_DM_PF      0x1F		// 1 1 1 1  1 0 0 0
72 #define BT_RFCOMM_DISC       0x53       // 1 1 0 0  1 0 1 0
73 #define BT_RFCOMM_UIH        0xEF       // 1 1 1 1  0 1 1 1
74 #define BT_RFCOMM_UIH_PF     0xFF       // 1 1 1 1  0 1 1 1
75 
76 // Multiplexer message types
77 #define BT_RFCOMM_CLD_CMD    0xC3
78 #define BT_RFCOMM_FCON_CMD   0xA3
79 #define BT_RFCOMM_FCON_RSP   0xA1
80 #define BT_RFCOMM_FCOFF_CMD  0x63
81 #define BT_RFCOMM_FCOFF_RSP  0x61
82 #define BT_RFCOMM_MSC_CMD    0xE3
83 #define BT_RFCOMM_MSC_RSP    0xE1
84 #define BT_RFCOMM_NSC_RSP    0x11
85 #define BT_RFCOMM_PN_CMD     0x83
86 #define BT_RFCOMM_PN_RSP     0x81
87 #define BT_RFCOMM_RLS_CMD    0x53
88 #define BT_RFCOMM_RLS_RSP    0x51
89 #define BT_RFCOMM_RPN_CMD    0x93
90 #define BT_RFCOMM_RPN_RSP    0x91
91 #define BT_RFCOMM_TEST_CMD   0x23
92 #define BT_RFCOMM_TEST_RSP   0x21
93 
94 #define RFCOMM_MULIPLEXER_TIMEOUT_MS 60000
95 
96 #define RFCOMM_CREDITS 10
97 
98 // FCS calc
99 #define BT_RFCOMM_CODE_WORD         0xE0 // pol = x8+x2+x1+1
100 #define BT_RFCOMM_CRC_CHECK_LEN     3
101 #define BT_RFCOMM_UIHCRC_CHECK_LEN  2
102 
103 #include "l2cap.h"
104 
105 // used for debugging
106 // #define RFCOMM_LOG_CREDITS
107 
108 // global rfcomm data
109 static uint16_t      rfcomm_client_cid_generator;  // used for client channel IDs
110 
111 // linked lists for all
112 static linked_list_t rfcomm_multiplexers = NULL;
113 static linked_list_t rfcomm_channels = NULL;
114 static linked_list_t rfcomm_services = NULL;
115 
116 static gap_security_level_t rfcomm_security_level;
117 
118 static void (*app_packet_handler)(void * connection, uint8_t packet_type,
119                                   uint16_t channel, uint8_t *packet, uint16_t size);
120 
121 static void rfcomm_run(void);
122 static void rfcomm_hand_out_credits(void);
123 static void rfcomm_channel_state_machine(rfcomm_channel_t *channel, rfcomm_channel_event_t *event);
124 static void rfcomm_channel_state_machine_2(rfcomm_multiplexer_t * multiplexer, uint8_t dlci, rfcomm_channel_event_t *event);
125 static int rfcomm_channel_ready_for_open(rfcomm_channel_t *channel);
126 static void rfcomm_multiplexer_state_machine(rfcomm_multiplexer_t * multiplexer, RFCOMM_MULTIPLEXER_EVENT event);
127 
128 
129 // MARK: RFCOMM CLIENT EVENTS
130 
131 // data: event (8), len(8), address(48), channel (8), rfcomm_cid (16)
132 static void rfcomm_emit_connection_request(rfcomm_channel_t *channel) {
133     log_info("RFCOMM_EVENT_INCOMING_CONNECTION addr %s channel #%u cid 0x%02x",
134              bd_addr_to_str(channel->multiplexer->remote_addr), channel->dlci>>1, channel->rfcomm_cid);
135     uint8_t event[11];
136     event[0] = RFCOMM_EVENT_INCOMING_CONNECTION;
137     event[1] = sizeof(event) - 2;
138     bt_flip_addr(&event[2], channel->multiplexer->remote_addr);
139     event[8] = channel->dlci >> 1;
140     bt_store_16(event, 9, channel->rfcomm_cid);
141     hci_dump_packet(HCI_EVENT_PACKET, 0, event, sizeof(event));
142 	(*app_packet_handler)(channel->connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
143 }
144 
145 // API Change: BTstack-0.3.50x uses
146 // data: event(8), len(8), status (8), address (48), server channel(8), rfcomm_cid(16), max frame size(16)
147 // next Cydia release will use SVN version of this
148 // data: event(8), len(8), status (8), address (48), handle (16), server channel(8), rfcomm_cid(16), max frame size(16)
149 static void rfcomm_emit_channel_opened(rfcomm_channel_t *channel, uint8_t status) {
150     log_info("RFCOMM_EVENT_OPEN_CHANNEL_COMPLETE status 0x%x addr %s handle 0x%x channel #%u cid 0x%02x mtu %u",
151              status, bd_addr_to_str(channel->multiplexer->remote_addr), channel->multiplexer->con_handle,
152              channel->dlci>>1, channel->rfcomm_cid, channel->max_frame_size);
153     uint8_t event[16];
154     uint8_t pos = 0;
155     event[pos++] = RFCOMM_EVENT_OPEN_CHANNEL_COMPLETE;  // 0
156     event[pos++] = sizeof(event) - 2;                   // 1
157     event[pos++] = status;                              // 2
158     bt_flip_addr(&event[pos], channel->multiplexer->remote_addr); pos += 6; // 3
159     bt_store_16(event,  pos, channel->multiplexer->con_handle);   pos += 2; // 9
160 	event[pos++] = channel->dlci >> 1;                                      // 11
161 	bt_store_16(event, pos, channel->rfcomm_cid); pos += 2;                 // 12 - channel ID
162 	bt_store_16(event, pos, channel->max_frame_size); pos += 2;   // max frame size
163     hci_dump_packet(HCI_EVENT_PACKET, 0, event, sizeof(event));
164 	(*app_packet_handler)(channel->connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, pos);
165 }
166 
167 // data: event(8), len(8), creidts incoming(8), new credits incoming(8), credits outgoing(8)
168 static inline void rfcomm_emit_credit_status(rfcomm_channel_t * channel) {
169 #ifdef RFCOMM_LOG_CREDITS
170     log_info("RFCOMM_LOG_CREDITS incoming %u new_incoming %u outgoing %u", channel->credits_incoming, channel->new_credits_incoming, channel->credits_outgoing);
171     uint8_t event[5];
172     event[0] = 0x88;
173     event[1] = sizeof(event) - 2;
174     event[2] = channel->credits_incoming;
175     event[3] = channel->new_credits_incoming;
176     event[4] = channel->credits_outgoing;
177     hci_dump_packet(HCI_EVENT_PACKET, 0, event, sizeof(event));
178 #endif
179 }
180 
181 // data: event(8), len(8), rfcomm_cid(16)
182 static void rfcomm_emit_channel_closed(rfcomm_channel_t * channel) {
183     log_info("RFCOMM_EVENT_CHANNEL_CLOSED cid 0x%02x", channel->rfcomm_cid);
184     uint8_t event[4];
185     event[0] = RFCOMM_EVENT_CHANNEL_CLOSED;
186     event[1] = sizeof(event) - 2;
187     bt_store_16(event, 2, channel->rfcomm_cid);
188     hci_dump_packet(HCI_EVENT_PACKET, 0, event, sizeof(event));
189 	(*app_packet_handler)(channel->connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
190 }
191 
192 static void rfcomm_emit_credits(rfcomm_channel_t * channel, uint8_t credits) {
193     log_info("RFCOMM_EVENT_CREDITS cid 0x%02x credits %u", channel->rfcomm_cid, credits);
194     uint8_t event[5];
195     event[0] = RFCOMM_EVENT_CREDITS;
196     event[1] = sizeof(event) - 2;
197     bt_store_16(event, 2, channel->rfcomm_cid);
198     event[4] = credits;
199     hci_dump_packet(HCI_EVENT_PACKET, 0, event, sizeof(event));
200 	(*app_packet_handler)(channel->connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
201 }
202 
203 static void rfcomm_emit_service_registered(void *connection, uint8_t status, uint8_t channel){
204     log_info("RFCOMM_EVENT_SERVICE_REGISTERED status 0x%x channel #%u", status, channel);
205     uint8_t event[4];
206     event[0] = RFCOMM_EVENT_SERVICE_REGISTERED;
207     event[1] = sizeof(event) - 2;
208     event[2] = status;
209     event[3] = channel;
210     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
211 	(*app_packet_handler)(connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
212 }
213 
214 static void rfcomm_emit_remote_line_status(rfcomm_channel_t *channel, uint8_t line_status){
215     log_info("RFCOMM_EVENT_REMOTE_LINE_STATUS cid 0x%02x c, line status 0x%x", channel->rfcomm_cid, line_status);
216     uint8_t event[5];
217     event[0] = RFCOMM_EVENT_REMOTE_LINE_STATUS;
218     event[1] = sizeof(event) - 2;
219     bt_store_16(event, 2, channel->rfcomm_cid);
220     event[4] = line_status;
221     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
222     (*app_packet_handler)(channel->connection, HCI_EVENT_PACKET, 0, (uint8_t *) event, sizeof(event));
223 }
224 
225 static void rfcomm_emit_port_configuration(rfcomm_channel_t *channel){
226     // notify client about new settings
227     uint8_t event[2+sizeof(rfcomm_rpn_data_t)];
228     event[0] = RFCOMM_EVENT_PORT_CONFIGURATION;
229     event[1] = sizeof(rfcomm_rpn_data_t);
230     memcpy(&event[2], (uint8_t*) &channel->rpn_data, sizeof(rfcomm_rpn_data_t));
231     hci_dump_packet( HCI_EVENT_PACKET, 0, event, sizeof(event));
232     (*app_packet_handler)(channel->connection, HCI_EVENT_PACKET, channel->rfcomm_cid, (uint8_t*)event, sizeof(event));
233 }
234 
235 // MARK RFCOMM RPN DATA HELPER
236 static void rfcomm_rpn_data_set_defaults(rfcomm_rpn_data_t * rpn_data){
237         rpn_data->baud_rate = RPN_BAUD_9600;  /* 9600 bps */
238         rpn_data->flags = 0x03;               /* 8-n-1 */
239         rpn_data->flow_control = 0;           /* no flow control */
240         rpn_data->xon  = 0xd1;                /* XON */
241         rpn_data->xoff = 0xd3;                /* XOFF */
242         rpn_data->parameter_mask_0 = 0x7f;    /* parameter mask, all values set */
243         rpn_data->parameter_mask_1 = 0x3f;    /* parameter mask, all values set */
244 }
245 
246 static void rfcomm_rpn_data_update(rfcomm_rpn_data_t * dest, rfcomm_rpn_data_t * src){
247     if (src->parameter_mask_0 & RPN_PARAM_MASK_0_BAUD){
248         dest->baud_rate = src->baud_rate;
249     }
250     if (src->parameter_mask_0 & RPN_PARAM_MASK_0_DATA_BITS){
251         dest->flags = (dest->flags & 0xfc) | (src->flags & 0x03);
252     }
253     if (src->parameter_mask_0 & RPN_PARAM_MASK_0_STOP_BITS){
254         dest->flags = (dest->flags & 0xfb) | (src->flags & 0x04);
255     }
256     if (src->parameter_mask_0 & RPN_PARAM_MASK_0_PARITY){
257         dest->flags = (dest->flags & 0xf7) | (src->flags & 0x08);
258     }
259     if (src->parameter_mask_0 & RPN_PARAM_MASK_0_PARITY_TYPE){
260         dest->flags = (dest->flags & 0xfc) | (src->flags & 0x30);
261     }
262     if (src->parameter_mask_0 & RPN_PARAM_MASK_0_XON_CHAR){
263         dest->xon = src->xon;
264     }
265     if (src->parameter_mask_0 & RPN_PARAM_MASK_0_XOFF_CHAR){
266         dest->xoff = src->xoff;
267     }
268     int i;
269     for (i=0; i < 6 ; i++){
270         uint8_t mask = 1 << i;
271         if (src->parameter_mask_1 & mask){
272             dest->flags = (dest->flags & ~mask) | (src->flags & mask);
273         }
274     }
275     // always copy parameter mask, too. informative for client, needed for response
276     dest->parameter_mask_0 = src->parameter_mask_0;
277     dest->parameter_mask_1 = src->parameter_mask_1;
278 }
279 // MARK: RFCOMM MULTIPLEXER HELPER
280 
281 static uint16_t rfcomm_max_frame_size_for_l2cap_mtu(uint16_t l2cap_mtu){
282     // Assume RFCOMM header without credits and 2 byte (14 bit) length field
283     uint16_t max_frame_size = l2cap_mtu - 5;
284     log_info("rfcomm_max_frame_size_for_l2cap_mtu:  %u -> %u", l2cap_mtu, max_frame_size);
285     return max_frame_size;
286 }
287 
288 static void rfcomm_multiplexer_initialize(rfcomm_multiplexer_t *multiplexer){
289 
290     memset(multiplexer, 0, sizeof(rfcomm_multiplexer_t));
291 
292     multiplexer->state = RFCOMM_MULTIPLEXER_CLOSED;
293     multiplexer->l2cap_credits = 0;
294     multiplexer->fcon = 1;
295     multiplexer->send_dm_for_dlci = 0;
296     multiplexer->max_frame_size = rfcomm_max_frame_size_for_l2cap_mtu(l2cap_max_mtu());
297     multiplexer->test_data_len = 0;
298     multiplexer->nsc_command = 0;
299 }
300 
301 static rfcomm_multiplexer_t * rfcomm_multiplexer_create_for_addr(bd_addr_t addr){
302 
303     // alloc structure
304     rfcomm_multiplexer_t * multiplexer = btstack_memory_rfcomm_multiplexer_get();
305     if (!multiplexer) return NULL;
306 
307     // fill in
308     rfcomm_multiplexer_initialize(multiplexer);
309     BD_ADDR_COPY(&multiplexer->remote_addr, addr);
310 
311     // add to services list
312     linked_list_add(&rfcomm_multiplexers, (linked_item_t *) multiplexer);
313 
314     return multiplexer;
315 }
316 
317 static rfcomm_multiplexer_t * rfcomm_multiplexer_for_addr(bd_addr_t addr){
318     linked_item_t *it;
319     for (it = (linked_item_t *) rfcomm_multiplexers; it ; it = it->next){
320         rfcomm_multiplexer_t * multiplexer = ((rfcomm_multiplexer_t *) it);
321         if (BD_ADDR_CMP(addr, multiplexer->remote_addr) == 0) {
322             return multiplexer;
323         };
324     }
325     return NULL;
326 }
327 
328 static rfcomm_multiplexer_t * rfcomm_multiplexer_for_l2cap_cid(uint16_t l2cap_cid) {
329     linked_item_t *it;
330     for (it = (linked_item_t *) rfcomm_multiplexers; it ; it = it->next){
331         rfcomm_multiplexer_t * multiplexer = ((rfcomm_multiplexer_t *) it);
332         if (multiplexer->l2cap_cid == l2cap_cid) {
333             return multiplexer;
334         };
335     }
336     return NULL;
337 }
338 
339 static int rfcomm_multiplexer_has_channels(rfcomm_multiplexer_t * multiplexer){
340     linked_item_t *it;
341     for (it = (linked_item_t *) rfcomm_channels; it ; it = it->next){
342         rfcomm_channel_t * channel = ((rfcomm_channel_t *) it);
343         if (channel->multiplexer == multiplexer) {
344             return 1;
345         }
346     }
347     return 0;
348 }
349 
350 // MARK: RFCOMM CHANNEL HELPER
351 
352 static void rfcomm_dump_channels(void){
353 #ifndef EMBEDDED
354     linked_item_t * it;
355     int channels = 0;
356     for (it = (linked_item_t *) rfcomm_channels; it ; it = it->next){
357         rfcomm_channel_t * channel = (rfcomm_channel_t *) it;
358         log_info("Channel #%u: addr %p, state %u", channels, channel, channel->state);
359         channels++;
360     }
361 #endif
362 }
363 
364 static void rfcomm_channel_initialize(rfcomm_channel_t *channel, rfcomm_multiplexer_t *multiplexer,
365                                rfcomm_service_t *service, uint8_t server_channel){
366 
367     // don't use 0 as channel id
368     if (rfcomm_client_cid_generator == 0) ++rfcomm_client_cid_generator;
369 
370     // setup channel
371     memset(channel, 0, sizeof(rfcomm_channel_t));
372 
373     channel->state             = RFCOMM_CHANNEL_CLOSED;
374     channel->state_var         = RFCOMM_CHANNEL_STATE_VAR_NONE;
375 
376     channel->multiplexer      = multiplexer;
377     channel->service          = service;
378     channel->rfcomm_cid       = rfcomm_client_cid_generator++;
379     channel->max_frame_size   = multiplexer->max_frame_size;
380 
381     channel->credits_incoming = 0;
382     channel->credits_outgoing = 0;
383     channel->packets_granted  = 0;
384 
385     // set defaults for port configuration (even for services)
386     rfcomm_rpn_data_set_defaults(&channel->rpn_data);
387 
388     // incoming flow control not active
389     channel->new_credits_incoming  =RFCOMM_CREDITS;
390     channel->incoming_flow_control = 0;
391 
392     channel->rls_line_status = RFCOMM_RLS_STATUS_INVALID;
393 
394 	if (service) {
395 		// incoming connection
396 		channel->outgoing = 0;
397 		channel->dlci = (server_channel << 1) |  multiplexer->outgoing;
398         if (channel->max_frame_size > service->max_frame_size) {
399             channel->max_frame_size = service->max_frame_size;
400         }
401         channel->incoming_flow_control = service->incoming_flow_control;
402         channel->new_credits_incoming  = service->incoming_initial_credits;
403 	} else {
404 		// outgoing connection
405 		channel->outgoing = 1;
406 		channel->dlci = (server_channel << 1) | (multiplexer->outgoing ^ 1);
407 
408 	}
409 }
410 
411 // service == NULL -> outgoing channel
412 static rfcomm_channel_t * rfcomm_channel_create(rfcomm_multiplexer_t * multiplexer,
413                                                 rfcomm_service_t * service, uint8_t server_channel){
414 
415     log_info("rfcomm_channel_create for service %p, channel %u --- list of channels:", service, server_channel);
416     rfcomm_dump_channels();
417 
418     // alloc structure
419     rfcomm_channel_t * channel = btstack_memory_rfcomm_channel_get();
420     if (!channel) return NULL;
421 
422     // fill in
423     rfcomm_channel_initialize(channel, multiplexer, service, server_channel);
424 
425     // add to services list
426     linked_list_add(&rfcomm_channels, (linked_item_t *) channel);
427 
428     return channel;
429 }
430 
431 static rfcomm_channel_t * rfcomm_channel_for_rfcomm_cid(uint16_t rfcomm_cid){
432     linked_item_t *it;
433     for (it = (linked_item_t *) rfcomm_channels; it ; it = it->next){
434         rfcomm_channel_t * channel = ((rfcomm_channel_t *) it);
435         if (channel->rfcomm_cid == rfcomm_cid) {
436             return channel;
437         };
438     }
439     return NULL;
440 }
441 
442 static rfcomm_channel_t * rfcomm_channel_for_multiplexer_and_dlci(rfcomm_multiplexer_t * multiplexer, uint8_t dlci){
443     linked_item_t *it;
444     for (it = (linked_item_t *) rfcomm_channels; it ; it = it->next){
445         rfcomm_channel_t * channel = ((rfcomm_channel_t *) it);
446         if (channel->dlci == dlci && channel->multiplexer == multiplexer) {
447             return channel;
448         };
449     }
450     return NULL;
451 }
452 
453 static rfcomm_service_t * rfcomm_service_for_channel(uint8_t server_channel){
454     linked_item_t *it;
455     for (it = (linked_item_t *) rfcomm_services; it ; it = it->next){
456         rfcomm_service_t * service = ((rfcomm_service_t *) it);
457         if ( service->server_channel == server_channel){
458             return service;
459         };
460     }
461     return NULL;
462 }
463 
464 // MARK: RFCOMM SEND
465 
466 /**
467  * @param credits - only used for RFCOMM flow control in UIH wiht P/F = 1
468  */
469 static int rfcomm_send_packet_for_multiplexer(rfcomm_multiplexer_t *multiplexer, uint8_t address, uint8_t control, uint8_t credits, uint8_t *data, uint16_t len){
470 
471     if (!l2cap_can_send_packet_now(multiplexer->l2cap_cid)) return BTSTACK_ACL_BUFFERS_FULL;
472 
473     l2cap_reserve_packet_buffer();
474     uint8_t * rfcomm_out_buffer = l2cap_get_outgoing_buffer();
475 
476 	uint16_t pos = 0;
477 	uint8_t crc_fields = 3;
478 
479 	rfcomm_out_buffer[pos++] = address;
480 	rfcomm_out_buffer[pos++] = control;
481 
482 	// length field can be 1 or 2 octets
483 	if (len < 128){
484 		rfcomm_out_buffer[pos++] = (len << 1)| 1;     // bits 0-6
485 	} else {
486 		rfcomm_out_buffer[pos++] = (len & 0x7f) << 1; // bits 0-6
487 		rfcomm_out_buffer[pos++] = len >> 7;          // bits 7-14
488 		crc_fields++;
489 	}
490 
491 	// add credits for UIH frames when PF bit is set
492 	if (control == BT_RFCOMM_UIH_PF){
493 		rfcomm_out_buffer[pos++] = credits;
494 	}
495 
496 	// copy actual data
497 	if (len) {
498 		memcpy(&rfcomm_out_buffer[pos], data, len);
499 		pos += len;
500 	}
501 
502 	// UIH frames only calc FCS over address + control (5.1.1)
503 	if ((control & 0xef) == BT_RFCOMM_UIH){
504 		crc_fields = 2;
505 	}
506 	rfcomm_out_buffer[pos++] =  crc8_calc(rfcomm_out_buffer, crc_fields); // calc fcs
507 
508     int credits_taken = 0;
509     if (multiplexer->l2cap_credits){
510         credits_taken++;
511         multiplexer->l2cap_credits--;
512     } else {
513         log_info( "rfcomm_send_packet addr %02x, ctrl %02x size %u without l2cap credits", address, control, pos);
514     }
515 
516     int err = l2cap_send_prepared(multiplexer->l2cap_cid, pos);
517 
518     if (err) {
519         // undo credit counting
520         multiplexer->l2cap_credits += credits_taken;
521     }
522     return err;
523 }
524 
525 // simplified version of rfcomm_send_packet_for_multiplexer for prepared rfcomm packet (UIH, 2 byte len, no credits)
526 static int rfcomm_send_uih_prepared(rfcomm_multiplexer_t *multiplexer, uint8_t dlci, uint16_t len){
527 
528     uint8_t address = (1 << 0) | (multiplexer->outgoing << 1) | (dlci << 2);
529     uint8_t control = BT_RFCOMM_UIH;
530 
531     uint8_t * rfcomm_out_buffer = l2cap_get_outgoing_buffer();
532 
533     uint16_t pos = 0;
534     rfcomm_out_buffer[pos++] = address;
535     rfcomm_out_buffer[pos++] = control;
536     rfcomm_out_buffer[pos++] = (len & 0x7f) << 1; // bits 0-6
537     rfcomm_out_buffer[pos++] = len >> 7;          // bits 7-14
538 
539     // actual data is already in place
540     pos += len;
541 
542     // UIH frames only calc FCS over address + control (5.1.1)
543     rfcomm_out_buffer[pos++] =  crc8_calc(rfcomm_out_buffer, 2); // calc fcs
544 
545     int credits_taken = 0;
546     if (multiplexer->l2cap_credits){
547         credits_taken++;
548         multiplexer->l2cap_credits--;
549     } else {
550         log_info( "rfcomm_send_uih_prepared addr %02x, ctrl %02x size %u without l2cap credits", address, control, pos);
551     }
552 
553     int err = l2cap_send_prepared(multiplexer->l2cap_cid, pos);
554 
555     if (err) {
556         // undo credit counting
557         multiplexer->l2cap_credits += credits_taken;
558     }
559     return err;
560 }
561 
562 // C/R Flag in Address
563 // - terms: initiator = station that creates multiplexer with SABM
564 // - terms: responder = station that responds to multiplexer setup with UA
565 // "For SABM, UA, DM and DISC frames C/R bit is set according to Table 1 in GSM 07.10, section 5.2.1.2"
566 //    - command initiator = 1 /response responder = 1
567 //    - command responder = 0 /response initiator = 0
568 // "For UIH frames, the C/R bit is always set according to section 5.4.3.1 in GSM 07.10.
569 //  This applies independently of what is contained wthin the UIH frames, either data or control messages."
570 //    - c/r = 1 for frames by initiating station, 0 = for frames by responding station
571 
572 // C/R Flag in Message
573 // "In the message level, the C/R bit in the command type field is set as stated in section 5.4.6.2 in GSM 07.10."
574 //   - If the C/R bit is set to 1 the message is a command
575 //   - if it is set to 0 the message is a response.
576 
577 // temp/old messge construction
578 
579 // new object oriented version
580 static int rfcomm_send_sabm(rfcomm_multiplexer_t *multiplexer, uint8_t dlci){
581 	uint8_t address = (1 << 0) | (multiplexer->outgoing << 1) | (dlci << 2);   // command
582     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_SABM, 0, NULL, 0);
583 }
584 
585 static int rfcomm_send_disc(rfcomm_multiplexer_t *multiplexer, uint8_t dlci){
586 	uint8_t address = (1 << 0) | (multiplexer->outgoing << 1) | (dlci << 2);  // command
587     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_DISC, 0, NULL, 0);
588 }
589 
590 static int rfcomm_send_ua(rfcomm_multiplexer_t *multiplexer, uint8_t dlci){
591 	uint8_t address = (1 << 0) | ((multiplexer->outgoing ^ 1) << 1) | (dlci << 2); // response
592     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UA, 0, NULL, 0);
593 }
594 
595 static int rfcomm_send_dm_pf(rfcomm_multiplexer_t *multiplexer, uint8_t dlci){
596 	uint8_t address = (1 << 0) | ((multiplexer->outgoing ^ 1) << 1) | (dlci << 2); // response
597     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_DM_PF, 0, NULL, 0);
598 }
599 
600 static int rfcomm_send_uih_fc_rsp(rfcomm_multiplexer_t *multiplexer, uint8_t fcon) {
601     uint8_t address = (1 << 0) | (multiplexer->outgoing<< 1);
602     uint8_t payload[2];
603     uint8_t pos = 0;
604     payload[pos++] = fcon ? BT_RFCOMM_FCON_RSP : BT_RFCOMM_FCOFF_RSP;
605     payload[pos++] = (0 << 1) | 1;  // len
606     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
607 }
608 
609 // static int rfcomm_send_uih_test_cmd(rfcomm_multiplexer_t *multiplexer, uint8_t * data, uint16_t len) {
610 //     uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
611 //     uint8_t payload[2+len];
612 //     uint8_t pos = 0;
613 //     payload[pos++] = BT_RFCOMM_TEST_CMD;
614 //     payload[pos++] = (len + 1) << 1 | 1;  // len
615 //     memcpy(&payload[pos], data, len);
616 //     pos += len;
617 //     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
618 // }
619 
620 static int rfcomm_send_uih_test_rsp(rfcomm_multiplexer_t *multiplexer, uint8_t * data, uint16_t len) {
621     uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
622     uint8_t payload[2+RFCOMM_TEST_DATA_MAX_LEN];
623     uint8_t pos = 0;
624     payload[pos++] = BT_RFCOMM_TEST_RSP;
625     if (len > RFCOMM_TEST_DATA_MAX_LEN) {
626         len = RFCOMM_TEST_DATA_MAX_LEN;
627     }
628     payload[pos++] = (len << 1) | 1;  // len
629     memcpy(&payload[pos], data, len);
630     pos += len;
631     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
632 }
633 
634 static int rfcomm_send_uih_msc_cmd(rfcomm_multiplexer_t *multiplexer, uint8_t dlci, uint8_t signals) {
635 	uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
636 	uint8_t payload[4];
637 	uint8_t pos = 0;
638 	payload[pos++] = BT_RFCOMM_MSC_CMD;
639 	payload[pos++] = (2 << 1) | 1;  // len
640 	payload[pos++] = (1 << 0) | (1 << 1) | (dlci << 2); // CMD => C/R = 1
641 	payload[pos++] = signals;
642 	return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
643 }
644 
645 static int rfcomm_send_uih_msc_rsp(rfcomm_multiplexer_t *multiplexer, uint8_t dlci, uint8_t signals) {
646 	uint8_t address = (1 << 0) | (multiplexer->outgoing<< 1);
647 	uint8_t payload[4];
648 	uint8_t pos = 0;
649 	payload[pos++] = BT_RFCOMM_MSC_RSP;
650 	payload[pos++] = (2 << 1) | 1;  // len
651 	payload[pos++] = (1 << 0) | (1 << 1) | (dlci << 2); // CMD => C/R = 1
652 	payload[pos++] = signals;
653 	return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
654 }
655 
656 static int rfcomm_send_uih_nsc_rsp(rfcomm_multiplexer_t *multiplexer, uint8_t command) {
657     uint8_t address = (1 << 0) | (multiplexer->outgoing<< 1);
658     uint8_t payload[3];
659     uint8_t pos = 0;
660     payload[pos++] = BT_RFCOMM_NSC_RSP;
661     payload[pos++] = (1 << 1) | 1;  // len
662     payload[pos++] = command;
663     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
664 }
665 
666 static int rfcomm_send_uih_pn_command(rfcomm_multiplexer_t *multiplexer, uint8_t dlci, uint16_t max_frame_size){
667 	uint8_t payload[10];
668 	uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
669 	uint8_t pos = 0;
670 	payload[pos++] = BT_RFCOMM_PN_CMD;
671 	payload[pos++] = (8 << 1) | 1;  // len
672 	payload[pos++] = dlci;
673 	payload[pos++] = 0xf0; // pre-defined for Bluetooth, see 5.5.3 of TS 07.10 Adaption for RFCOMM
674 	payload[pos++] = 0; // priority
675 	payload[pos++] = 0; // max 60 seconds ack
676 	payload[pos++] = max_frame_size & 0xff; // max framesize low
677 	payload[pos++] = max_frame_size >> 8;   // max framesize high
678 	payload[pos++] = 0x00; // number of retransmissions
679 	payload[pos++] = 0x00; // (unused error recovery window) initial number of credits
680 	return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
681 }
682 
683 // "The response may not change the DLCI, the priority, the convergence layer, or the timer value." RFCOMM-tutorial.pdf
684 static int rfcomm_send_uih_pn_response(rfcomm_multiplexer_t *multiplexer, uint8_t dlci,
685                                        uint8_t priority, uint16_t max_frame_size){
686 	uint8_t payload[10];
687 	uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
688 	uint8_t pos = 0;
689 	payload[pos++] = BT_RFCOMM_PN_RSP;
690 	payload[pos++] = (8 << 1) | 1;  // len
691 	payload[pos++] = dlci;
692 	payload[pos++] = 0xe0; // pre defined for Bluetooth, see 5.5.3 of TS 07.10 Adaption for RFCOMM
693 	payload[pos++] = priority; // priority
694 	payload[pos++] = 0; // max 60 seconds ack
695 	payload[pos++] = max_frame_size & 0xff; // max framesize low
696 	payload[pos++] = max_frame_size >> 8;   // max framesize high
697 	payload[pos++] = 0x00; // number of retransmissions
698 	payload[pos++] = 0x00; // (unused error recovery window) initial number of credits
699 	return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
700 }
701 
702 static int rfcomm_send_uih_rls_cmd(rfcomm_multiplexer_t *multiplexer, uint8_t dlci, uint8_t line_status) {
703     uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
704     uint8_t payload[4];
705     uint8_t pos = 0;
706     payload[pos++] = BT_RFCOMM_RLS_CMD;
707     payload[pos++] = (2 << 1) | 1;  // len
708     payload[pos++] = (1 << 0) | (1 << 1) | (dlci << 2); // CMD => C/R = 1
709     payload[pos++] = line_status;
710     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
711 }
712 
713 static int rfcomm_send_uih_rls_rsp(rfcomm_multiplexer_t *multiplexer, uint8_t dlci, uint8_t line_status) {
714     uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
715     uint8_t payload[4];
716     uint8_t pos = 0;
717     payload[pos++] = BT_RFCOMM_RLS_RSP;
718     payload[pos++] = (2 << 1) | 1;  // len
719     payload[pos++] = (1 << 0) | (1 << 1) | (dlci << 2); // CMD => C/R = 1
720     payload[pos++] = line_status;
721     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
722 }
723 
724 static int rfcomm_send_uih_rpn_cmd(rfcomm_multiplexer_t *multiplexer, uint8_t dlci, rfcomm_rpn_data_t *rpn_data) {
725     uint8_t payload[10];
726     uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
727     uint8_t pos = 0;
728     payload[pos++] = BT_RFCOMM_RPN_CMD;
729     payload[pos++] = (8 << 1) | 1;  // len
730     payload[pos++] = (1 << 0) | (1 << 1) | (dlci << 2); // CMD => C/R = 1
731     payload[pos++] = rpn_data->baud_rate;
732     payload[pos++] = rpn_data->flags;
733     payload[pos++] = rpn_data->flow_control;
734     payload[pos++] = rpn_data->xon;
735     payload[pos++] = rpn_data->xoff;
736     payload[pos++] = rpn_data->parameter_mask_0;
737     payload[pos++] = rpn_data->parameter_mask_1;
738     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
739 }
740 
741 static int rfcomm_send_uih_rpn_req(rfcomm_multiplexer_t *multiplexer, uint8_t dlci) {
742     uint8_t payload[3];
743     uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
744     uint8_t pos = 0;
745     payload[pos++] = BT_RFCOMM_RPN_CMD;
746     payload[pos++] = (1 << 1) | 1;  // len
747     payload[pos++] = (1 << 0) | (1 << 1) | (dlci << 2); // CMD => C/R = 1
748     return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
749 }
750 
751 static int rfcomm_send_uih_rpn_rsp(rfcomm_multiplexer_t *multiplexer, uint8_t dlci, rfcomm_rpn_data_t *rpn_data) {
752 	uint8_t payload[10];
753 	uint8_t address = (1 << 0) | (multiplexer->outgoing << 1);
754 	uint8_t pos = 0;
755 	payload[pos++] = BT_RFCOMM_RPN_RSP;
756 	payload[pos++] = (8 << 1) | 1;  // len
757 	payload[pos++] = (1 << 0) | (1 << 1) | (dlci << 2); // CMD => C/R = 1
758 	payload[pos++] = rpn_data->baud_rate;
759 	payload[pos++] = rpn_data->flags;
760 	payload[pos++] = rpn_data->flow_control;
761 	payload[pos++] = rpn_data->xon;
762 	payload[pos++] = rpn_data->xoff;
763 	payload[pos++] = rpn_data->parameter_mask_0;
764 	payload[pos++] = rpn_data->parameter_mask_1;
765 	return rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH, 0, (uint8_t *) payload, pos);
766 }
767 
768 static void rfcomm_send_uih_credits(rfcomm_multiplexer_t *multiplexer, uint8_t dlci,  uint8_t credits){
769     uint8_t address = (1 << 0) | (multiplexer->outgoing << 1) |  (dlci << 2);
770     rfcomm_send_packet_for_multiplexer(multiplexer, address, BT_RFCOMM_UIH_PF, credits, NULL, 0);
771 }
772 
773 // MARK: RFCOMM MULTIPLEXER
774 static void rfcomm_multiplexer_stop_timer(rfcomm_multiplexer_t * multiplexer){
775     if (multiplexer->timer_active) {
776         run_loop_remove_timer(&multiplexer->timer);
777         multiplexer->timer_active = 0;
778     }
779 }
780 static void rfcomm_multiplexer_free(rfcomm_multiplexer_t * multiplexer){
781     linked_list_remove( &rfcomm_multiplexers, (linked_item_t *) multiplexer);
782     btstack_memory_rfcomm_multiplexer_free(multiplexer);
783 }
784 
785 static void rfcomm_multiplexer_finalize(rfcomm_multiplexer_t * multiplexer){
786     // remove (potential) timer
787     rfcomm_multiplexer_stop_timer(multiplexer);
788 
789     // close and remove all channels
790     linked_item_t *it = (linked_item_t *) &rfcomm_channels;
791     while (it->next){
792         rfcomm_channel_t * channel = (rfcomm_channel_t *) it->next;
793         if (channel->multiplexer == multiplexer) {
794             // emit appropriate events
795             if (channel->state == RFCOMM_CHANNEL_OPEN) {
796                 rfcomm_emit_channel_closed(channel);
797             } else {
798                 rfcomm_emit_channel_opened(channel, RFCOMM_MULTIPLEXER_STOPPED);
799             }
800             // remove from list
801             it->next = it->next->next;
802             // free channel struct
803             btstack_memory_rfcomm_channel_free(channel);
804         } else {
805             it = it->next;
806         }
807     }
808 
809     // remove mutliplexer
810     rfcomm_multiplexer_free(multiplexer);
811 }
812 
813 static void rfcomm_multiplexer_timer_handler(timer_source_t *timer){
814     rfcomm_multiplexer_t * multiplexer = (rfcomm_multiplexer_t *) linked_item_get_user( (linked_item_t *) timer);
815     if (rfcomm_multiplexer_has_channels(multiplexer)) return;
816 
817     log_info("rfcomm_multiplexer_timer_handler timeout: shutting down multiplexer! (no channels)");
818     uint16_t l2cap_cid = multiplexer->l2cap_cid;
819     rfcomm_multiplexer_finalize(multiplexer);
820     l2cap_disconnect_internal(l2cap_cid, 0x13);
821 }
822 
823 static void rfcomm_multiplexer_prepare_idle_timer(rfcomm_multiplexer_t * multiplexer){
824     if (multiplexer->timer_active) {
825         run_loop_remove_timer(&multiplexer->timer);
826         multiplexer->timer_active = 0;
827     }
828     if (rfcomm_multiplexer_has_channels(multiplexer)) return;
829 
830     // start idle timer for multiplexer timeout check as there are no rfcomm channels yet
831     run_loop_set_timer(&multiplexer->timer, RFCOMM_MULIPLEXER_TIMEOUT_MS);
832     multiplexer->timer.process = rfcomm_multiplexer_timer_handler;
833     linked_item_set_user((linked_item_t*) &multiplexer->timer, multiplexer);
834     run_loop_add_timer(&multiplexer->timer);
835     multiplexer->timer_active = 1;
836 }
837 
838 static void rfcomm_multiplexer_opened(rfcomm_multiplexer_t *multiplexer){
839     log_info("Multiplexer up and running");
840     multiplexer->state = RFCOMM_MULTIPLEXER_OPEN;
841 
842     rfcomm_channel_event_t event = { CH_EVT_MULTIPLEXER_READY };
843 
844     // transition of channels that wait for multiplexer
845     linked_item_t *it;
846     for (it = (linked_item_t *) rfcomm_channels; it ; it = it->next){
847         rfcomm_channel_t * channel = ((rfcomm_channel_t *) it);
848         if (channel->multiplexer != multiplexer) continue;
849         rfcomm_channel_state_machine(channel, &event);
850     }
851 
852     rfcomm_run();
853     rfcomm_multiplexer_prepare_idle_timer(multiplexer);
854 }
855 
856 
857 /**
858  * @return handled packet
859  */
860 static int rfcomm_multiplexer_hci_event_handler(uint8_t *packet, uint16_t size){
861     bd_addr_t event_addr;
862     uint16_t  psm;
863     uint16_t l2cap_cid;
864     hci_con_handle_t con_handle;
865     rfcomm_multiplexer_t *multiplexer = NULL;
866     uint8_t status;
867 
868     switch (packet[0]) {
869 
870         // accept incoming PSM_RFCOMM connection if no multiplexer exists yet
871         case L2CAP_EVENT_INCOMING_CONNECTION:
872             // data: event(8), len(8), address(48), handle (16),  psm (16), source cid(16) dest cid(16)
873             bt_flip_addr(event_addr, &packet[2]);
874             con_handle = READ_BT_16(packet,  8);
875             psm        = READ_BT_16(packet, 10);
876             l2cap_cid  = READ_BT_16(packet, 12);
877 
878             if (psm != PSM_RFCOMM) break;
879 
880             multiplexer = rfcomm_multiplexer_for_addr(event_addr);
881 
882             if (multiplexer) {
883                 log_info("INCOMING_CONNECTION (l2cap_cid 0x%02x) for PSM_RFCOMM => decline - multiplexer already exists", l2cap_cid);
884                 l2cap_decline_connection_internal(l2cap_cid,  0x04);    // no resources available
885                 return 1;
886             }
887 
888             // create and inititialize new multiplexer instance (incoming)
889             multiplexer = rfcomm_multiplexer_create_for_addr(event_addr);
890             if (!multiplexer){
891                 log_info("INCOMING_CONNECTION (l2cap_cid 0x%02x) for PSM_RFCOMM => decline - no memory left", l2cap_cid);
892                 l2cap_decline_connection_internal(l2cap_cid,  0x04);    // no resources available
893                 return 1;
894             }
895 
896             multiplexer->con_handle = con_handle;
897             multiplexer->l2cap_cid = l2cap_cid;
898             multiplexer->state = RFCOMM_MULTIPLEXER_W4_SABM_0;
899 
900             log_info("L2CAP_EVENT_INCOMING_CONNECTION (l2cap_cid 0x%02x) for PSM_RFCOMM => accept", l2cap_cid);
901             l2cap_accept_connection_internal(l2cap_cid);
902             return 1;
903 
904         // l2cap connection opened -> store l2cap_cid, remote_addr
905         case L2CAP_EVENT_CHANNEL_OPENED:
906 
907             if (READ_BT_16(packet, 11) != PSM_RFCOMM) break;
908 
909             status = packet[2];
910             log_info("L2CAP_EVENT_CHANNEL_OPENED for PSM_RFCOMM, status %u", status);
911 
912             // get multiplexer for remote addr
913             con_handle = READ_BT_16(packet, 9);
914             l2cap_cid = READ_BT_16(packet, 13);
915             bt_flip_addr(event_addr, &packet[3]);
916             multiplexer = rfcomm_multiplexer_for_addr(event_addr);
917             if (!multiplexer) {
918                 log_error("L2CAP_EVENT_CHANNEL_OPENED but no multiplexer prepared");
919                 return 1;
920             }
921 
922             // on l2cap open error discard everything
923             if (status){
924 
925                 // remove (potential) timer
926                 rfcomm_multiplexer_stop_timer(multiplexer);
927 
928                 // emit rfcomm_channel_opened with status and free channel
929                 linked_item_t * it = (linked_item_t *) &rfcomm_channels;
930                 while (it->next) {
931                     rfcomm_channel_t * channel = (rfcomm_channel_t *) it->next;
932                     if (channel->multiplexer == multiplexer){
933                         rfcomm_emit_channel_opened(channel, status);
934                         it->next = it->next->next;
935                         btstack_memory_rfcomm_channel_free(channel);
936                     } else {
937                         it = it->next;
938                     }
939                 }
940 
941                 // free multiplexer
942                 rfcomm_multiplexer_free(multiplexer);
943                 return 1;
944             }
945 
946             if (multiplexer->state == RFCOMM_MULTIPLEXER_W4_CONNECT) {
947                 log_info("L2CAP_EVENT_CHANNEL_OPENED: outgoing connection");
948                 // wrong remote addr
949                 if (BD_ADDR_CMP(event_addr, multiplexer->remote_addr)) break;
950                 multiplexer->l2cap_cid = l2cap_cid;
951                 multiplexer->con_handle = con_handle;
952                 // send SABM #0
953                 multiplexer->state = RFCOMM_MULTIPLEXER_SEND_SABM_0;
954             } else { // multiplexer->state == RFCOMM_MULTIPLEXER_W4_SABM_0
955 
956                 // set max frame size based on l2cap MTU
957                 multiplexer->max_frame_size = rfcomm_max_frame_size_for_l2cap_mtu(READ_BT_16(packet, 17));
958             }
959             return 1;
960 
961             // l2cap disconnect -> state = RFCOMM_MULTIPLEXER_CLOSED;
962 
963         case L2CAP_EVENT_CREDITS:
964             // data: event(8), len(8), local_cid(16), credits(8)
965             l2cap_cid = READ_BT_16(packet, 2);
966             multiplexer = rfcomm_multiplexer_for_l2cap_cid(l2cap_cid);
967             if (!multiplexer) break;
968             multiplexer->l2cap_credits += packet[4];
969 
970             // log_info("L2CAP_EVENT_CREDITS: %u (now %u)", packet[4], multiplexer->l2cap_credits);
971 
972             // new credits, continue with signaling
973             rfcomm_run();
974 
975             if (multiplexer->state != RFCOMM_MULTIPLEXER_OPEN) break;
976             rfcomm_hand_out_credits();
977             return 1;
978 
979         case DAEMON_EVENT_HCI_PACKET_SENT:
980             // testing DMA done code
981             rfcomm_run();
982             break;
983 
984         case L2CAP_EVENT_CHANNEL_CLOSED:
985             // data: event (8), len(8), channel (16)
986             l2cap_cid = READ_BT_16(packet, 2);
987             multiplexer = rfcomm_multiplexer_for_l2cap_cid(l2cap_cid);
988             log_info("L2CAP_EVENT_CHANNEL_CLOSED cid 0x%0x, mult %p", l2cap_cid, multiplexer);
989             if (!multiplexer) break;
990             log_info("L2CAP_EVENT_CHANNEL_CLOSED state %u", multiplexer->state);
991             switch (multiplexer->state) {
992                 case RFCOMM_MULTIPLEXER_W4_CONNECT:
993                 case RFCOMM_MULTIPLEXER_SEND_SABM_0:
994                 case RFCOMM_MULTIPLEXER_W4_SABM_0:
995                 case RFCOMM_MULTIPLEXER_SEND_UA_0:
996                 case RFCOMM_MULTIPLEXER_W4_UA_0:
997                 case RFCOMM_MULTIPLEXER_OPEN:
998                     // don't call l2cap_disconnect as it's alreay closed
999                     rfcomm_multiplexer_finalize(multiplexer);
1000                     return 1;
1001                 default:
1002                     break;
1003             }
1004             break;
1005         default:
1006             break;
1007     }
1008     return 0;
1009 }
1010 
1011 static int rfcomm_multiplexer_l2cap_packet_handler(uint16_t channel, uint8_t *packet, uint16_t size){
1012 
1013     // get or create a multiplexer for a certain device
1014     rfcomm_multiplexer_t *multiplexer = rfcomm_multiplexer_for_l2cap_cid(channel);
1015     if (!multiplexer) return 0;
1016 
1017     uint16_t l2cap_cid = multiplexer->l2cap_cid;
1018 
1019 	// but only care for multiplexer control channel
1020     uint8_t frame_dlci = packet[0] >> 2;
1021     if (frame_dlci) return 0;
1022     const uint8_t length_offset = (packet[2] & 1) ^ 1;  // to be used for pos >= 3
1023     const uint8_t credit_offset = ((packet[1] & BT_RFCOMM_UIH_PF) == BT_RFCOMM_UIH_PF) ? 1 : 0;   // credits for uih_pf frames
1024     const uint8_t payload_offset = 3 + length_offset + credit_offset;
1025     switch (packet[1]){
1026 
1027         case BT_RFCOMM_SABM:
1028             if (multiplexer->state == RFCOMM_MULTIPLEXER_W4_SABM_0){
1029                 log_info("Received SABM #0");
1030                 multiplexer->outgoing = 0;
1031                 multiplexer->state = RFCOMM_MULTIPLEXER_SEND_UA_0;
1032                 return 1;
1033             }
1034             break;
1035 
1036         case BT_RFCOMM_UA:
1037             if (multiplexer->state == RFCOMM_MULTIPLEXER_W4_UA_0) {
1038                 // UA #0 -> send UA #0, state = RFCOMM_MULTIPLEXER_OPEN
1039                 log_info("Received UA #0 ");
1040                 rfcomm_multiplexer_opened(multiplexer);
1041                 return 1;
1042             }
1043             break;
1044 
1045         case BT_RFCOMM_DISC:
1046             // DISC #0 -> send UA #0, close multiplexer
1047             log_info("Received DISC #0, (ougoing = %u)", multiplexer->outgoing);
1048             multiplexer->state = RFCOMM_MULTIPLEXER_SEND_UA_0_AND_DISC;
1049             return 1;
1050 
1051         case BT_RFCOMM_DM:
1052             // DM #0 - we shouldn't get this, just give up
1053             log_info("Received DM #0");
1054             log_info("-> Closing down multiplexer");
1055             rfcomm_multiplexer_finalize(multiplexer);
1056             l2cap_disconnect_internal(l2cap_cid, 0x13);
1057             return 1;
1058 
1059         case BT_RFCOMM_UIH:
1060             if (packet[payload_offset] == BT_RFCOMM_CLD_CMD){
1061                 // Multiplexer close down (CLD) -> close mutliplexer
1062                 log_info("Received Multiplexer close down command");
1063                 log_info("-> Closing down multiplexer");
1064                 rfcomm_multiplexer_finalize(multiplexer);
1065                 l2cap_disconnect_internal(l2cap_cid, 0x13);
1066                 return 1;
1067             }
1068             switch (packet[payload_offset]){
1069                 case BT_RFCOMM_CLD_CMD:
1070                      // Multiplexer close down (CLD) -> close mutliplexer
1071                     log_info("Received Multiplexer close down command");
1072                     log_info("-> Closing down multiplexer");
1073                     rfcomm_multiplexer_finalize(multiplexer);
1074                     l2cap_disconnect_internal(l2cap_cid, 0x13);
1075                     return 1;
1076 
1077                 case BT_RFCOMM_FCON_CMD:
1078                     multiplexer->fcon = 0x81;
1079                     break;
1080 
1081                 case BT_RFCOMM_FCOFF_CMD:
1082                     multiplexer->fcon = 0x80;
1083                     break;
1084 
1085                 case BT_RFCOMM_TEST_CMD: {
1086                     log_info("Received test command");
1087                     int len = packet[payload_offset+1] >> 1; // length < 125
1088                     if (len > RFCOMM_TEST_DATA_MAX_LEN){
1089                         len = RFCOMM_TEST_DATA_MAX_LEN;
1090                     }
1091                     multiplexer->test_data_len = len;
1092                     memcpy(multiplexer->test_data, &packet[payload_offset + 2], len);
1093                     return 1;
1094                 }
1095                 default:
1096                     break;
1097             }
1098             break;
1099 
1100         default:
1101             break;
1102 
1103     }
1104     return 0;
1105 }
1106 
1107 static void rfcomm_multiplexer_state_machine(rfcomm_multiplexer_t * multiplexer, RFCOMM_MULTIPLEXER_EVENT event){
1108 
1109     uint16_t l2cap_cid = multiplexer->l2cap_cid;
1110 
1111     // process stored DM responses
1112     if (multiplexer->send_dm_for_dlci){
1113         uint8_t dlci = multiplexer->send_dm_for_dlci;
1114         multiplexer->send_dm_for_dlci = 0;
1115         rfcomm_send_dm_pf(multiplexer, dlci);
1116         return;
1117     }
1118 
1119     if (multiplexer->nsc_command){
1120         uint8_t command = multiplexer->nsc_command;
1121         multiplexer->nsc_command = 0;
1122         rfcomm_send_uih_nsc_rsp(multiplexer, command);
1123         return;
1124     }
1125 
1126     if (multiplexer->fcon & 0x80){
1127         multiplexer->fcon &= 0x01;
1128         rfcomm_send_uih_fc_rsp(multiplexer, multiplexer->fcon);
1129         if (multiplexer->fcon == 0) return;
1130         // trigger client to send again after sending FCon Response
1131         uint8_t packet_sent_event[] = { DAEMON_EVENT_HCI_PACKET_SENT, 0};
1132         linked_item_t *it;
1133         for (it = (linked_item_t *) rfcomm_channels; it ; it = it->next){
1134             rfcomm_channel_t * channel = ((rfcomm_channel_t *) it);
1135             if (channel->multiplexer != multiplexer) continue;
1136             (*app_packet_handler)(channel->connection, HCI_EVENT_PACKET, 0, (uint8_t *) packet_sent_event, sizeof(packet_sent_event));
1137         }
1138         return;
1139     }
1140 
1141     switch (multiplexer->state) {
1142         case RFCOMM_MULTIPLEXER_SEND_SABM_0:
1143             switch (event) {
1144                 case MULT_EV_READY_TO_SEND:
1145                     log_info("Sending SABM #0 - (multi 0x%p)", multiplexer);
1146                     multiplexer->state = RFCOMM_MULTIPLEXER_W4_UA_0;
1147                     rfcomm_send_sabm(multiplexer, 0);
1148                     break;
1149                 default:
1150                     break;
1151             }
1152             break;
1153         case RFCOMM_MULTIPLEXER_SEND_UA_0:
1154             switch (event) {
1155                 case MULT_EV_READY_TO_SEND:
1156                     log_info("Sending UA #0");
1157                     multiplexer->state = RFCOMM_MULTIPLEXER_OPEN;
1158                     rfcomm_send_ua(multiplexer, 0);
1159                     rfcomm_multiplexer_opened(multiplexer);
1160                     break;
1161                 default:
1162                     break;
1163             }
1164             break;
1165         case RFCOMM_MULTIPLEXER_SEND_UA_0_AND_DISC:
1166             switch (event) {
1167                 case MULT_EV_READY_TO_SEND:
1168                     // try to detect authentication errors: drop link key if multiplexer closed before first channel got opened
1169                     if (!multiplexer->at_least_one_connection){
1170                         log_info("TODO: no connections established - delete link key prophylactically");
1171                         // hci_send_cmd(&hci_delete_stored_link_key, multiplexer->remote_addr);
1172                     }
1173                     log_info("Sending UA #0");
1174                     log_info("Closing down multiplexer");
1175                     multiplexer->state = RFCOMM_MULTIPLEXER_CLOSED;
1176                     rfcomm_send_ua(multiplexer, 0);
1177                     rfcomm_multiplexer_finalize(multiplexer);
1178                     l2cap_disconnect_internal(l2cap_cid, 0x13);
1179                 default:
1180                     break;
1181             }
1182             break;
1183         case RFCOMM_MULTIPLEXER_OPEN:
1184             switch (event) {
1185                 case MULT_EV_READY_TO_SEND:
1186                     // respond to test command
1187                     if (multiplexer->test_data_len){
1188                         int len = multiplexer->test_data_len;
1189                         log_info("Sending TEST Response with %u bytes", len);
1190                         multiplexer->test_data_len = 0;
1191                         rfcomm_send_uih_test_rsp(multiplexer, multiplexer->test_data, len);
1192                         return;
1193                     }
1194                     break;
1195                 default:
1196                     break;
1197             }
1198             break;
1199         default:
1200             break;
1201     }
1202 }
1203 
1204 // MARK: RFCOMM CHANNEL
1205 
1206 static void rfcomm_hand_out_credits(void){
1207     linked_item_t * it;
1208     for (it = (linked_item_t *) rfcomm_channels; it ; it = it->next){
1209         rfcomm_channel_t * channel = (rfcomm_channel_t *) it;
1210         if (channel->state != RFCOMM_CHANNEL_OPEN) {
1211             // log_info("RFCOMM_EVENT_CREDITS: multiplexer not open");
1212             continue;
1213         }
1214         if (channel->packets_granted) {
1215             // log_info("RFCOMM_EVENT_CREDITS: already packets granted");
1216             continue;
1217         }
1218         if (!channel->credits_outgoing) {
1219             // log_info("RFCOMM_EVENT_CREDITS: no outgoing credits");
1220             continue;
1221         }
1222         if (!channel->multiplexer->l2cap_credits){
1223             // log_info("RFCOMM_EVENT_CREDITS: no l2cap credits");
1224             continue;
1225         }
1226         // channel open, multiplexer has l2cap credits and we didn't hand out credit before -> go!
1227         // log_info("RFCOMM_EVENT_CREDITS: 1");
1228         channel->packets_granted += 1;
1229         rfcomm_emit_credits(channel, 1);
1230     }
1231 }
1232 
1233 static void rfcomm_channel_send_credits(rfcomm_channel_t *channel, uint8_t credits){
1234     rfcomm_send_uih_credits(channel->multiplexer, channel->dlci, credits);
1235     channel->credits_incoming += credits;
1236 
1237     rfcomm_emit_credit_status(channel);
1238 }
1239 
1240 static void rfcomm_channel_opened(rfcomm_channel_t *rfChannel){
1241 
1242     log_info("rfcomm_channel_opened!");
1243 
1244     rfChannel->state = RFCOMM_CHANNEL_OPEN;
1245     rfcomm_emit_channel_opened(rfChannel, 0);
1246     rfcomm_emit_port_configuration(rfChannel);
1247     rfcomm_hand_out_credits();
1248 
1249     // remove (potential) timer
1250     rfcomm_multiplexer_t *multiplexer = rfChannel->multiplexer;
1251     if (multiplexer->timer_active) {
1252         run_loop_remove_timer(&multiplexer->timer);
1253         multiplexer->timer_active = 0;
1254     }
1255     // hack for problem detecting authentication failure
1256     multiplexer->at_least_one_connection = 1;
1257 
1258     // start next connection request if pending
1259     rfcomm_run();
1260 }
1261 
1262 static void rfcomm_channel_packet_handler_uih(rfcomm_multiplexer_t *multiplexer, uint8_t * packet, uint16_t size){
1263     const uint8_t frame_dlci = packet[0] >> 2;
1264     const uint8_t length_offset = (packet[2] & 1) ^ 1;  // to be used for pos >= 3
1265     const uint8_t credit_offset = ((packet[1] & BT_RFCOMM_UIH_PF) == BT_RFCOMM_UIH_PF) ? 1 : 0;   // credits for uih_pf frames
1266     const uint8_t payload_offset = 3 + length_offset + credit_offset;
1267 
1268     rfcomm_channel_t * channel = rfcomm_channel_for_multiplexer_and_dlci(multiplexer, frame_dlci);
1269     if (!channel) return;
1270 
1271     // handle new outgoing credits
1272     if (packet[1] == BT_RFCOMM_UIH_PF) {
1273 
1274         // add them
1275         uint16_t new_credits = packet[3+length_offset];
1276         channel->credits_outgoing += new_credits;
1277         log_info( "RFCOMM data UIH_PF, new credits: %u, now %u", new_credits, channel->credits_outgoing);
1278 
1279         // notify channel statemachine
1280         rfcomm_channel_event_t channel_event = { CH_EVT_RCVD_CREDITS };
1281         rfcomm_channel_state_machine(channel, &channel_event);
1282     }
1283 
1284     // contains payload?
1285     if (size - 1 > payload_offset){
1286 
1287         // log_info( "RFCOMM data UIH_PF, size %u, channel %p", size-payload_offset-1, rfChannel->connection);
1288 
1289         // decrease incoming credit counter
1290         if (channel->credits_incoming > 0){
1291             channel->credits_incoming--;
1292         }
1293 
1294         // deliver payload
1295         (*app_packet_handler)(channel->connection, RFCOMM_DATA_PACKET, channel->rfcomm_cid,
1296                               &packet[payload_offset], size-payload_offset-1);
1297     }
1298 
1299     // automatically provide new credits to remote device, if no incoming flow control
1300     if (!channel->incoming_flow_control && channel->credits_incoming < 5){
1301         channel->new_credits_incoming =RFCOMM_CREDITS;
1302     }
1303 
1304     rfcomm_emit_credit_status(channel);
1305 
1306     // we received new RFCOMM credits, hand them out if possible
1307     rfcomm_hand_out_credits();
1308 }
1309 
1310 static void rfcomm_channel_accept_pn(rfcomm_channel_t *channel, rfcomm_channel_event_pn_t *event){
1311     // priority of client request
1312     channel->pn_priority = event->priority;
1313 
1314     // new credits
1315     channel->credits_outgoing = event->credits_outgoing;
1316 
1317     // negotiate max frame size
1318     if (channel->max_frame_size > channel->multiplexer->max_frame_size) {
1319         channel->max_frame_size = channel->multiplexer->max_frame_size;
1320     }
1321     if (channel->max_frame_size > event->max_frame_size) {
1322         channel->max_frame_size = event->max_frame_size;
1323     }
1324 
1325 }
1326 
1327 static void rfcomm_channel_finalize(rfcomm_channel_t *channel){
1328 
1329     rfcomm_multiplexer_t *multiplexer = channel->multiplexer;
1330 
1331     // remove from list
1332     linked_list_remove( &rfcomm_channels, (linked_item_t *) channel);
1333 
1334     // free channel
1335     btstack_memory_rfcomm_channel_free(channel);
1336 
1337     // update multiplexer timeout after channel was removed from list
1338     rfcomm_multiplexer_prepare_idle_timer(multiplexer);
1339 }
1340 
1341 static void rfcomm_channel_state_machine_2(rfcomm_multiplexer_t * multiplexer, uint8_t dlci, rfcomm_channel_event_t *event){
1342 
1343     // TODO: if client max frame size is smaller than RFCOMM_DEFAULT_SIZE, send PN
1344 
1345 
1346     // lookup existing channel
1347     rfcomm_channel_t * channel = rfcomm_channel_for_multiplexer_and_dlci(multiplexer, dlci);
1348 
1349     // log_info("rfcomm_channel_state_machine_2 lookup dlci #%u = 0x%08x - event %u", dlci, (int) channel, event->type);
1350 
1351     if (channel) {
1352         rfcomm_channel_state_machine(channel, event);
1353         return;
1354     }
1355 
1356     // service registered?
1357     rfcomm_service_t * service = rfcomm_service_for_channel(dlci >> 1);
1358     // log_info("rfcomm_channel_state_machine_2 service dlci #%u = 0x%08x", dlci, (int) service);
1359     if (!service) {
1360         // discard request by sending disconnected mode
1361         multiplexer->send_dm_for_dlci = dlci;
1362         return;
1363     }
1364 
1365     // create channel for some events
1366     switch (event->type) {
1367         case CH_EVT_RCVD_SABM:
1368         case CH_EVT_RCVD_PN:
1369         case CH_EVT_RCVD_RPN_REQ:
1370         case CH_EVT_RCVD_RPN_CMD:
1371             // setup incoming channel
1372             channel = rfcomm_channel_create(multiplexer, service, dlci >> 1);
1373             if (!channel){
1374                 // discard request by sending disconnected mode
1375                 multiplexer->send_dm_for_dlci = dlci;
1376             }
1377             break;
1378         default:
1379             break;
1380     }
1381 
1382     if (!channel) {
1383         // discard request by sending disconnected mode
1384         multiplexer->send_dm_for_dlci = dlci;
1385         return;
1386     }
1387     channel->connection = service->connection;
1388     rfcomm_channel_state_machine(channel, event);
1389 }
1390 
1391 static void rfcomm_channel_packet_handler(rfcomm_multiplexer_t * multiplexer,  uint8_t *packet, uint16_t size){
1392 
1393     // rfcomm: (0) addr [76543 server channel] [2 direction: initiator uses 1] [1 C/R: CMD by initiator = 1] [0 EA=1]
1394     const uint8_t frame_dlci = packet[0] >> 2;
1395     uint8_t message_dlci; // used by commands in UIH(_PF) packets
1396 	uint8_t message_len;  //   "
1397 
1398     // rfcomm: (1) command/control
1399     // -- credits_offset = 1 if command == BT_RFCOMM_UIH_PF
1400     const uint8_t credit_offset = ((packet[1] & BT_RFCOMM_UIH_PF) == BT_RFCOMM_UIH_PF) ? 1 : 0;   // credits for uih_pf frames
1401     // rfcomm: (2) length. if bit 0 is cleared, 2 byte length is used. (little endian)
1402     const uint8_t length_offset = (packet[2] & 1) ^ 1;  // to be used for pos >= 3
1403     // rfcomm: (3+length_offset) credits if credits_offset == 1
1404     // rfcomm: (3+length_offest+credits_offset)
1405     const uint8_t payload_offset = 3 + length_offset + credit_offset;
1406 
1407     rfcomm_channel_event_t event;
1408     rfcomm_channel_event_pn_t event_pn;
1409     rfcomm_channel_event_rpn_t event_rpn;
1410     rfcomm_channel_event_msc_t event_msc;
1411 
1412     // switch by rfcomm message type
1413     switch(packet[1]) {
1414 
1415         case BT_RFCOMM_SABM:
1416             event.type = CH_EVT_RCVD_SABM;
1417             log_info("Received SABM #%u", frame_dlci);
1418             rfcomm_channel_state_machine_2(multiplexer, frame_dlci, &event);
1419             break;
1420 
1421         case BT_RFCOMM_UA:
1422             event.type = CH_EVT_RCVD_UA;
1423             log_info("Received UA #%u",frame_dlci);
1424             rfcomm_channel_state_machine_2(multiplexer, frame_dlci, &event);
1425             break;
1426 
1427         case BT_RFCOMM_DISC:
1428             event.type = CH_EVT_RCVD_DISC;
1429             rfcomm_channel_state_machine_2(multiplexer, frame_dlci, &event);
1430             break;
1431 
1432         case BT_RFCOMM_DM:
1433         case BT_RFCOMM_DM_PF:
1434             event.type = CH_EVT_RCVD_DM;
1435             rfcomm_channel_state_machine_2(multiplexer, frame_dlci, &event);
1436             break;
1437 
1438         case BT_RFCOMM_UIH_PF:
1439         case BT_RFCOMM_UIH:
1440 
1441             message_len  = packet[payload_offset+1] >> 1;
1442 
1443             switch (packet[payload_offset]) {
1444                 case BT_RFCOMM_PN_CMD:
1445                     message_dlci = packet[payload_offset+2];
1446                     event_pn.super.type = CH_EVT_RCVD_PN;
1447                     event_pn.priority = packet[payload_offset+4];
1448                     event_pn.max_frame_size = READ_BT_16(packet, payload_offset+6);
1449                     event_pn.credits_outgoing = packet[payload_offset+9];
1450                     log_info("Received UIH Parameter Negotiation Command for #%u, credits %u",
1451                         message_dlci, event_pn.credits_outgoing);
1452                     rfcomm_channel_state_machine_2(multiplexer, message_dlci, (rfcomm_channel_event_t*) &event_pn);
1453                     break;
1454 
1455                 case BT_RFCOMM_PN_RSP:
1456                     message_dlci = packet[payload_offset+2];
1457                     event_pn.super.type = CH_EVT_RCVD_PN_RSP;
1458                     event_pn.priority = packet[payload_offset+4];
1459                     event_pn.max_frame_size = READ_BT_16(packet, payload_offset+6);
1460                     event_pn.credits_outgoing = packet[payload_offset+9];
1461                     log_info("Received UIH Parameter Negotiation Response max frame %u, credits %u",
1462                             event_pn.max_frame_size, event_pn.credits_outgoing);
1463                     rfcomm_channel_state_machine_2(multiplexer, message_dlci, (rfcomm_channel_event_t*) &event_pn);
1464                     break;
1465 
1466                 case BT_RFCOMM_MSC_CMD:
1467                     message_dlci = packet[payload_offset+2] >> 2;
1468                     event_msc.super.type = CH_EVT_RCVD_MSC_CMD;
1469                     event_msc.modem_status = packet[payload_offset+3];
1470                     log_info("Received MSC CMD for #%u, ", message_dlci);
1471                     rfcomm_channel_state_machine_2(multiplexer, message_dlci, (rfcomm_channel_event_t*) &event_msc);
1472                     break;
1473 
1474                 case BT_RFCOMM_MSC_RSP:
1475                     message_dlci = packet[payload_offset+2] >> 2;
1476                     event.type = CH_EVT_RCVD_MSC_RSP;
1477                     log_info("Received MSC RSP for #%u", message_dlci);
1478                     rfcomm_channel_state_machine_2(multiplexer, message_dlci, &event);
1479                     break;
1480 
1481                 case BT_RFCOMM_RPN_CMD:
1482                     message_dlci = packet[payload_offset+2] >> 2;
1483                     switch (message_len){
1484                         case 1:
1485                             log_info("Received Remote Port Negotiation Request for #%u", message_dlci);
1486                             event.type = CH_EVT_RCVD_RPN_REQ;
1487                             rfcomm_channel_state_machine_2(multiplexer, message_dlci, &event);
1488                             break;
1489                         case 8:
1490                             log_info("Received Remote Port Negotiation Update for #%u", message_dlci);
1491                             event_rpn.super.type = CH_EVT_RCVD_RPN_CMD;
1492                             event_rpn.data = *(rfcomm_rpn_data_t*) &packet[payload_offset+3];
1493                             rfcomm_channel_state_machine_2(multiplexer, message_dlci, (rfcomm_channel_event_t*) &event_rpn);
1494                             break;
1495                         default:
1496                             break;
1497                     }
1498                     break;
1499 
1500                 case BT_RFCOMM_RPN_RSP:
1501                     log_info("Received RPN response");
1502                     break;
1503 
1504                 case BT_RFCOMM_RLS_CMD: {
1505                     log_info("Received RLS command");
1506                     message_dlci = packet[payload_offset+2] >> 2;
1507                     rfcomm_channel_event_rls_t event_rls;
1508                     event_rls.super.type = CH_EVT_RCVD_RLS_CMD;
1509                     event_rls.line_status = packet[payload_offset+3];
1510                     rfcomm_channel_state_machine_2(multiplexer, message_dlci, (rfcomm_channel_event_t*) &event_rls);
1511                     break;
1512                 }
1513 
1514                 case BT_RFCOMM_RLS_RSP:
1515                     log_info("Received RLS response");
1516                     break;
1517 
1518                 // Following commands are handled by rfcomm_multiplexer_l2cap_packet_handler
1519                 // case BT_RFCOMM_TEST_CMD:
1520                 // case BT_RFCOMM_FCOFF_CMD:
1521                 // case BT_RFCOMM_FCON_CMD:
1522                 // everything else is an not supported command
1523                 default: {
1524                     log_error("Received unknown UIH command packet - 0x%02x", packet[payload_offset]);
1525                     multiplexer->nsc_command = packet[payload_offset];
1526                     break;
1527                 }
1528             }
1529             break;
1530 
1531         default:
1532             log_error("Received unknown RFCOMM message type %x", packet[1]);
1533             break;
1534     }
1535 
1536     // trigger next action - example W4_PN_RSP: transition to SEND_SABM which only depends on "can send"
1537     rfcomm_run();
1538 }
1539 
1540 void rfcomm_packet_handler(uint8_t packet_type, uint16_t channel, uint8_t *packet, uint16_t size){
1541 
1542     // multiplexer handler
1543     int handled = 0;
1544     switch (packet_type) {
1545         case HCI_EVENT_PACKET:
1546             handled = rfcomm_multiplexer_hci_event_handler(packet, size);
1547             break;
1548         case L2CAP_DATA_PACKET:
1549             handled = rfcomm_multiplexer_l2cap_packet_handler(channel, packet, size);
1550             break;
1551         default:
1552             break;
1553     }
1554 
1555     if (handled) {
1556         rfcomm_run();
1557         return;
1558     }
1559 
1560     // we only handle l2cap packet over open multiplexer channel now
1561     if (packet_type != L2CAP_DATA_PACKET) {
1562         (*app_packet_handler)(NULL, packet_type, channel, packet, size);
1563         return;
1564     }
1565     rfcomm_multiplexer_t * multiplexer = rfcomm_multiplexer_for_l2cap_cid(channel);
1566     if (!multiplexer || multiplexer->state != RFCOMM_MULTIPLEXER_OPEN) {
1567         (*app_packet_handler)(NULL, packet_type, channel, packet, size);
1568         return;
1569     }
1570 
1571     // channel data ?
1572     // rfcomm: (0) addr [76543 server channel] [2 direction: initiator uses 1] [1 C/R: CMD by initiator = 1] [0 EA=1]
1573     const uint8_t frame_dlci = packet[0] >> 2;
1574 
1575     if (frame_dlci && (packet[1] == BT_RFCOMM_UIH || packet[1] == BT_RFCOMM_UIH_PF)) {
1576         rfcomm_channel_packet_handler_uih(multiplexer, packet, size);
1577         rfcomm_run();
1578         return;
1579     }
1580 
1581     rfcomm_channel_packet_handler(multiplexer, packet, size);
1582 }
1583 
1584 static int rfcomm_channel_ready_for_open(rfcomm_channel_t *channel){
1585     // note: exchanging MSC isn't neccessary to consider channel open
1586     // note: having outgoing credits is also not necessary to consider channel open
1587     // log_info("rfcomm_channel_ready_for_open state %u, flags needed %04x, current %04x, rf credits %u, l2cap credits %u ", channel->state, RFCOMM_CHANNEL_STATE_VAR_RCVD_MSC_RSP|RFCOMM_CHANNEL_STATE_VAR_SENT_MSC_RSP|RFCOMM_CHANNEL_STATE_VAR_SENT_CREDITS, channel->state_var, channel->credits_outgoing, channel->multiplexer->l2cap_credits);
1588     // if ((channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SENT_MSC_RSP) == 0) return 0;
1589     // if (channel->credits_outgoing == 0) return 0;
1590     log_info("rfcomm_channel_ready_for_open state %u, flags needed %04x, current %04x, rf credits %u, l2cap credits %u ", channel->state, RFCOMM_CHANNEL_STATE_VAR_RCVD_MSC_RSP, channel->state_var, channel->credits_outgoing, channel->multiplexer->l2cap_credits);
1591     if ((channel->state_var & RFCOMM_CHANNEL_STATE_VAR_RCVD_MSC_RSP) == 0) return 0;
1592     if ((channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SENT_CREDITS) == 0) return 0;
1593 
1594     return 1;
1595 }
1596 
1597 static int rfcomm_channel_ready_for_incoming_dlc_setup(rfcomm_channel_t * channel){
1598     log_info("rfcomm_channel_ready_for_incoming_dlc_setup state var %04x", channel->state_var);
1599     // Client accept and SABM/UA is required, PN RSP is needed if PN was received
1600     if ((channel->state_var & RFCOMM_CHANNEL_STATE_VAR_CLIENT_ACCEPTED) == 0) return 0;
1601     if ((channel->state_var & RFCOMM_CHANNEL_STATE_VAR_RCVD_SABM      ) == 0) return 0;
1602     if ((channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SEND_UA        ) != 0) return 0;
1603     if ((channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SEND_PN_RSP    ) != 0) return 0;
1604     return 1;
1605 }
1606 
1607 inline static void rfcomm_channel_state_add(rfcomm_channel_t *channel, RFCOMM_CHANNEL_STATE_VAR event){
1608     channel->state_var = (RFCOMM_CHANNEL_STATE_VAR) (channel->state_var | event);
1609 }
1610 inline static void rfcomm_channel_state_remove(rfcomm_channel_t *channel, RFCOMM_CHANNEL_STATE_VAR event){
1611     channel->state_var = (RFCOMM_CHANNEL_STATE_VAR) (channel->state_var & ~event);
1612 }
1613 
1614 static void rfcomm_channel_state_machine(rfcomm_channel_t *channel, rfcomm_channel_event_t *event){
1615 
1616     // log_info("rfcomm_channel_state_machine: state %u, state_var %04x, event %u", channel->state, channel->state_var ,event->type);
1617 
1618     rfcomm_multiplexer_t *multiplexer = channel->multiplexer;
1619 
1620     // TODO: integrate in common switch
1621     if (event->type == CH_EVT_RCVD_DISC){
1622         rfcomm_emit_channel_closed(channel);
1623         channel->state = RFCOMM_CHANNEL_SEND_UA_AFTER_DISC;
1624         return;
1625     }
1626 
1627     // TODO: integrate in common switch
1628     if (event->type == CH_EVT_RCVD_DM){
1629         log_info("Received DM message for #%u", channel->dlci);
1630         log_info("-> Closing channel locally for #%u", channel->dlci);
1631         rfcomm_emit_channel_closed(channel);
1632         rfcomm_channel_finalize(channel);
1633         return;
1634     }
1635 
1636     // remote port negotiation command - just accept everything for now
1637     //
1638     // "The RPN command can be used before a new DLC is opened and should be used whenever the port settings change."
1639     // "The RPN command is specified as optional in TS 07.10, but it is mandatory to recognize and respond to it in RFCOMM.
1640     //   (Although the handling of individual settings are implementation-dependent.)"
1641     //
1642 
1643     // TODO: integrate in common switch
1644     if (event->type == CH_EVT_RCVD_RPN_CMD){
1645         // control port parameters
1646         rfcomm_channel_event_rpn_t *event_rpn = (rfcomm_channel_event_rpn_t*) event;
1647         rfcomm_rpn_data_update(&channel->rpn_data, &event_rpn->data);
1648         rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_RPN_RSP);
1649         // notify client about new settings
1650         rfcomm_emit_port_configuration(channel);
1651         return;
1652     }
1653 
1654     // TODO: integrate in common switch
1655     if (event->type == CH_EVT_RCVD_RPN_REQ){
1656         // no values got accepted (no values have beens sent)
1657         channel->rpn_data.parameter_mask_0 = 0x00;
1658         channel->rpn_data.parameter_mask_1 = 0x00;
1659         rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_RPN_RSP);
1660         return;
1661     }
1662 
1663     if (event->type == CH_EVT_RCVD_RLS_CMD){
1664         rfcomm_channel_event_rls_t * event_rls = (rfcomm_channel_event_rls_t*) event;
1665         channel->rls_line_status = event_rls->line_status & 0x0f;
1666         log_info("CH_EVT_RCVD_RLS_CMD setting line status to 0x%0x", channel->rls_line_status);
1667         rfcomm_emit_remote_line_status(channel, event_rls->line_status);
1668         return;
1669     }
1670 
1671     // TODO: integrate in common swich
1672     if (event->type == CH_EVT_READY_TO_SEND){
1673         if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SEND_RPN_RSP){
1674             log_info("Sending Remote Port Negotiation RSP for #%u", channel->dlci);
1675             rfcomm_channel_state_remove(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_RPN_RSP);
1676             rfcomm_send_uih_rpn_rsp(multiplexer, channel->dlci, &channel->rpn_data);
1677             return;
1678         }
1679         if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SEND_MSC_RSP){
1680             log_info("Sending MSC RSP for #%u", channel->dlci);
1681             rfcomm_channel_state_remove(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_MSC_RSP);
1682             rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SENT_MSC_RSP);
1683             rfcomm_send_uih_msc_rsp(multiplexer, channel->dlci, 0x8d);  // ea=1,fc=0,rtc=1,rtr=1,ic=0,dv=1
1684             return;
1685         }
1686         if (channel->rls_line_status != RFCOMM_RLS_STATUS_INVALID){
1687             log_info("Sending RLS RSP 0x%0x", channel->rls_line_status);
1688             uint8_t line_status = channel->rls_line_status;
1689             channel->rls_line_status = RFCOMM_RLS_STATUS_INVALID;
1690             rfcomm_send_uih_rls_rsp(multiplexer, channel->dlci, line_status);
1691             return;
1692         }
1693     }
1694 
1695     // emit MSC status to app
1696     if (event->type == CH_EVT_RCVD_MSC_CMD){
1697         // notify client about new settings
1698         rfcomm_channel_event_msc_t *event_msc = (rfcomm_channel_event_msc_t*) event;
1699         uint8_t modem_status_event[2+1];
1700         modem_status_event[0] = RFCOMM_EVENT_REMOTE_MODEM_STATUS;
1701         modem_status_event[1] = 1;
1702         modem_status_event[2] = event_msc->modem_status;
1703         (*app_packet_handler)(channel->connection, HCI_EVENT_PACKET, channel->rfcomm_cid, (uint8_t*)&modem_status_event, sizeof(modem_status_event));
1704         // no return, MSC_CMD will be handled by state machine below
1705     }
1706 
1707     rfcomm_channel_event_pn_t * event_pn = (rfcomm_channel_event_pn_t*) event;
1708 
1709     switch (channel->state) {
1710         case RFCOMM_CHANNEL_CLOSED:
1711             switch (event->type){
1712                 case CH_EVT_RCVD_SABM:
1713                     log_info("-> Inform app");
1714                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_RCVD_SABM);
1715                     channel->state = RFCOMM_CHANNEL_INCOMING_SETUP;
1716                     rfcomm_emit_connection_request(channel);
1717                     break;
1718                 case CH_EVT_RCVD_PN:
1719                     rfcomm_channel_accept_pn(channel, event_pn);
1720                     log_info("-> Inform app");
1721                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_RCVD_PN);
1722                     channel->state = RFCOMM_CHANNEL_INCOMING_SETUP;
1723                     rfcomm_emit_connection_request(channel);
1724                     break;
1725                 default:
1726                     break;
1727             }
1728             break;
1729 
1730         case RFCOMM_CHANNEL_INCOMING_SETUP:
1731             switch (event->type){
1732                 case CH_EVT_RCVD_SABM:
1733                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_RCVD_SABM);
1734                     if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_CLIENT_ACCEPTED) {
1735                         rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_UA);
1736                     }
1737                     break;
1738                 case CH_EVT_RCVD_PN:
1739                     rfcomm_channel_accept_pn(channel, event_pn);
1740                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_RCVD_PN);
1741                     if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_CLIENT_ACCEPTED) {
1742                         rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_PN_RSP);
1743                     }
1744                     break;
1745                 case CH_EVT_READY_TO_SEND:
1746                     // if / else if is used to check for state transition after sending
1747                     if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SEND_PN_RSP){
1748                         log_info("Sending UIH Parameter Negotiation Respond for #%u", channel->dlci);
1749                         rfcomm_channel_state_remove(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_PN_RSP);
1750                         rfcomm_send_uih_pn_response(multiplexer, channel->dlci, channel->pn_priority, channel->max_frame_size);
1751                     } else if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SEND_UA){
1752                         log_info("Sending UA #%u", channel->dlci);
1753                         rfcomm_channel_state_remove(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_UA);
1754                         rfcomm_send_ua(multiplexer, channel->dlci);
1755                     }
1756                     if (rfcomm_channel_ready_for_incoming_dlc_setup(channel)){
1757                         log_info("Incomping setup done, requesting send MSC CMD and send Credits");
1758                         rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_MSC_CMD);
1759                         rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_CREDITS);
1760                         channel->state = RFCOMM_CHANNEL_DLC_SETUP;
1761                     }
1762                     break;
1763                 default:
1764                     break;
1765             }
1766             break;
1767 
1768         case RFCOMM_CHANNEL_W4_MULTIPLEXER:
1769             switch (event->type) {
1770                 case CH_EVT_MULTIPLEXER_READY:
1771                     log_info("Muliplexer opened, sending UIH PN next");
1772                     channel->state = RFCOMM_CHANNEL_SEND_UIH_PN;
1773                     break;
1774                 default:
1775                     break;
1776             }
1777             break;
1778 
1779         case RFCOMM_CHANNEL_SEND_UIH_PN:
1780             switch (event->type) {
1781                 case CH_EVT_READY_TO_SEND:
1782                     log_info("Sending UIH Parameter Negotiation Command for #%u (channel 0x%p)", channel->dlci, channel );
1783                     channel->state = RFCOMM_CHANNEL_W4_PN_RSP;
1784                     rfcomm_send_uih_pn_command(multiplexer, channel->dlci, channel->max_frame_size);
1785                     break;
1786                 default:
1787                     break;
1788             }
1789             break;
1790 
1791         case RFCOMM_CHANNEL_W4_PN_RSP:
1792             switch (event->type){
1793                 case CH_EVT_RCVD_PN_RSP:
1794                     // update max frame size
1795                     if (channel->max_frame_size > event_pn->max_frame_size) {
1796                         channel->max_frame_size = event_pn->max_frame_size;
1797                     }
1798                     // new credits
1799                     channel->credits_outgoing = event_pn->credits_outgoing;
1800                     channel->state = RFCOMM_CHANNEL_SEND_SABM_W4_UA;
1801                     break;
1802                 default:
1803                     break;
1804             }
1805             break;
1806 
1807         case RFCOMM_CHANNEL_SEND_SABM_W4_UA:
1808             switch (event->type) {
1809                 case CH_EVT_READY_TO_SEND:
1810                     log_info("Sending SABM #%u", channel->dlci);
1811                     channel->state = RFCOMM_CHANNEL_W4_UA;
1812                     rfcomm_send_sabm(multiplexer, channel->dlci);
1813                     break;
1814                 default:
1815                     break;
1816             }
1817             break;
1818 
1819         case RFCOMM_CHANNEL_W4_UA:
1820             switch (event->type){
1821                 case CH_EVT_RCVD_UA:
1822                     channel->state = RFCOMM_CHANNEL_DLC_SETUP;
1823                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_MSC_CMD);
1824                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_CREDITS);
1825                     break;
1826                 default:
1827                     break;
1828             }
1829             break;
1830 
1831         case RFCOMM_CHANNEL_DLC_SETUP:
1832             switch (event->type){
1833                 case CH_EVT_RCVD_MSC_CMD:
1834                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_RCVD_MSC_CMD);
1835                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_MSC_RSP);
1836                     break;
1837                 case CH_EVT_RCVD_MSC_RSP:
1838                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_RCVD_MSC_RSP);
1839                     break;
1840 
1841                 case CH_EVT_READY_TO_SEND:
1842                     if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SEND_MSC_CMD){
1843                         log_info("Sending MSC CMD for #%u", channel->dlci);
1844                         rfcomm_channel_state_remove(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_MSC_CMD);
1845                         rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SENT_MSC_CMD);
1846                         rfcomm_send_uih_msc_cmd(multiplexer, channel->dlci , 0x8d);  // ea=1,fc=0,rtc=1,rtr=1,ic=0,dv=1
1847                         break;
1848                     }
1849                     if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_SEND_CREDITS){
1850                         log_info("Providing credits for #%u", channel->dlci);
1851                         rfcomm_channel_state_remove(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_CREDITS);
1852                         rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SENT_CREDITS);
1853 
1854                         if (channel->new_credits_incoming) {
1855                             uint8_t new_credits = channel->new_credits_incoming;
1856                             channel->new_credits_incoming = 0;
1857                             rfcomm_channel_send_credits(channel, new_credits);
1858                         }
1859                         break;
1860 
1861                     }
1862                     break;
1863                 default:
1864                     break;
1865             }
1866             // finally done?
1867             if (rfcomm_channel_ready_for_open(channel)){
1868                 channel->state = RFCOMM_CHANNEL_OPEN;
1869                 rfcomm_channel_opened(channel);
1870             }
1871             break;
1872 
1873         case RFCOMM_CHANNEL_OPEN:
1874             switch (event->type){
1875                 case CH_EVT_RCVD_MSC_CMD:
1876                     rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_MSC_RSP);
1877                     break;
1878                 case CH_EVT_READY_TO_SEND:
1879                     if (channel->new_credits_incoming) {
1880                         uint8_t new_credits = channel->new_credits_incoming;
1881                         channel->new_credits_incoming = 0;
1882                         rfcomm_channel_send_credits(channel, new_credits);
1883                         break;
1884                     }
1885                     break;
1886                 case CH_EVT_RCVD_CREDITS: {
1887                     // notify daemon -> might trigger re-try of parked connections
1888                     uint8_t credits_event[2] = { DAEMON_EVENT_NEW_RFCOMM_CREDITS, 0 };
1889                     (*app_packet_handler)(channel->connection, DAEMON_EVENT_PACKET, channel->rfcomm_cid, credits_event, sizeof(credits_event));
1890                     break;
1891                 }
1892                 default:
1893                     break;
1894             }
1895             break;
1896 
1897         case RFCOMM_CHANNEL_SEND_DM:
1898             switch (event->type) {
1899                 case CH_EVT_READY_TO_SEND:
1900                     log_info("Sending DM_PF for #%u", channel->dlci);
1901                     // don't emit channel closed - channel was never open
1902                     channel->state = RFCOMM_CHANNEL_CLOSED;
1903                     rfcomm_send_dm_pf(multiplexer, channel->dlci);
1904                     rfcomm_channel_finalize(channel);
1905                     break;
1906                 default:
1907                     break;
1908             }
1909             break;
1910 
1911         case RFCOMM_CHANNEL_SEND_DISC:
1912             switch (event->type) {
1913                 case CH_EVT_READY_TO_SEND:
1914                     channel->state = RFCOMM_CHANNEL_W4_UA_AFTER_UA;
1915                     rfcomm_send_disc(multiplexer, channel->dlci);
1916                     break;
1917                 default:
1918                     break;
1919             }
1920             break;
1921 
1922         case RFCOMM_CHANNEL_W4_UA_AFTER_UA:
1923             switch (event->type){
1924                 case CH_EVT_RCVD_UA:
1925                     channel->state = RFCOMM_CHANNEL_CLOSED;
1926                     rfcomm_emit_channel_closed(channel);
1927                     rfcomm_channel_finalize(channel);
1928                     break;
1929                 default:
1930                     break;
1931             }
1932             break;
1933 
1934         case RFCOMM_CHANNEL_SEND_UA_AFTER_DISC:
1935             switch (event->type) {
1936                 case CH_EVT_READY_TO_SEND:
1937                     log_info("Sending UA after DISC for #%u", channel->dlci);
1938                     channel->state = RFCOMM_CHANNEL_CLOSED;
1939                     rfcomm_send_ua(multiplexer, channel->dlci);
1940                     rfcomm_channel_finalize(channel);
1941                     break;
1942                 default:
1943                     break;
1944             }
1945             break;
1946 
1947         default:
1948             break;
1949     }
1950 }
1951 
1952 
1953 // MARK: RFCOMM RUN
1954 // process outstanding signaling tasks
1955 static void rfcomm_run(void){
1956 
1957     linked_item_t *it;
1958     linked_item_t *next;
1959 
1960     for (it = (linked_item_t *) rfcomm_multiplexers; it ; it = next){
1961 
1962         next = it->next;    // be prepared for removal of channel in state machine
1963 
1964         rfcomm_multiplexer_t * multiplexer = ((rfcomm_multiplexer_t *) it);
1965 
1966         if (!l2cap_can_send_packet_now(multiplexer->l2cap_cid)) {
1967             // log_info("rfcomm_run A cannot send l2cap packet for #%u, credits %u", multiplexer->l2cap_cid, multiplexer->l2cap_credits);
1968             continue;
1969         }
1970         // log_info("rfcomm_run: multi 0x%08x, state %u", (int) multiplexer, multiplexer->state);
1971 
1972         rfcomm_multiplexer_state_machine(multiplexer, MULT_EV_READY_TO_SEND);
1973     }
1974 
1975     for (it = (linked_item_t *) rfcomm_channels; it ; it = next){
1976 
1977         next = it->next;    // be prepared for removal of channel in state machine
1978 
1979         rfcomm_channel_t * channel = ((rfcomm_channel_t *) it);
1980         rfcomm_multiplexer_t * multiplexer = channel->multiplexer;
1981 
1982         if (!l2cap_can_send_packet_now(multiplexer->l2cap_cid)) {
1983             // log_info("rfcomm_run B cannot send l2cap packet for #%u, credits %u", multiplexer->l2cap_cid, multiplexer->l2cap_credits);
1984             continue;
1985         }
1986 
1987         rfcomm_channel_event_t event = { CH_EVT_READY_TO_SEND };
1988         rfcomm_channel_state_machine(channel, &event);
1989     }
1990 }
1991 
1992 // MARK: RFCOMM BTstack API
1993 
1994 void rfcomm_init(void){
1995     rfcomm_client_cid_generator = 0;
1996     rfcomm_multiplexers = NULL;
1997     rfcomm_services     = NULL;
1998     rfcomm_channels     = NULL;
1999     rfcomm_security_level = LEVEL_2;
2000 }
2001 
2002 void rfcomm_set_required_security_level(gap_security_level_t security_level){
2003     rfcomm_security_level = security_level;
2004 }
2005 
2006 // register packet handler
2007 void rfcomm_register_packet_handler(void (*handler)(void * connection, uint8_t packet_type,
2008                                                     uint16_t channel, uint8_t *packet, uint16_t size)){
2009 	app_packet_handler = handler;
2010 }
2011 
2012 int rfcomm_can_send_packet_now(uint16_t rfcomm_cid){
2013     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2014     if (!channel){
2015         log_error("rfcomm_send_internal cid 0x%02x doesn't exist!", rfcomm_cid);
2016         return 1;
2017     }
2018     if (!channel->credits_outgoing) return 0;
2019     if (!channel->packets_granted)  return 0;
2020     if ((channel->multiplexer->fcon & 1) == 0) return 0;
2021 
2022     return l2cap_can_send_packet_now(channel->multiplexer->l2cap_cid);
2023 }
2024 
2025 static int rfcomm_assert_send_valid(rfcomm_channel_t * channel , uint16_t len){
2026     if (len > channel->max_frame_size){
2027         log_error("rfcomm_send_internal cid 0x%02x, rfcomm data lenght exceeds MTU!", channel->rfcomm_cid);
2028         return RFCOMM_DATA_LEN_EXCEEDS_MTU;
2029     }
2030 
2031     if (!channel->credits_outgoing){
2032         log_info("rfcomm_send_internal cid 0x%02x, no rfcomm outgoing credits!", channel->rfcomm_cid);
2033         return RFCOMM_NO_OUTGOING_CREDITS;
2034     }
2035 
2036     if (!channel->packets_granted){
2037         log_info("rfcomm_send_internal cid 0x%02x, no rfcomm credits granted!", channel->rfcomm_cid);
2038         return RFCOMM_NO_OUTGOING_CREDITS;
2039     }
2040 
2041     if ((channel->multiplexer->fcon & 1) == 0){
2042         log_info("rfcomm_send_internal cid 0x%02x, aggregate flow off!", channel->rfcomm_cid);
2043         return RFCOMM_AGGREGATE_FLOW_OFF;
2044     }
2045     return 0;
2046 }
2047 
2048 // pre: rfcomm_can_send_packet_now(rfcomm_cid) == true
2049 int rfcomm_reserve_packet_buffer(void){
2050     return l2cap_reserve_packet_buffer();
2051 }
2052 
2053 void rfcomm_release_packet_buffer(void){
2054     l2cap_release_packet_buffer();
2055 }
2056 
2057 uint8_t * rfcomm_get_outgoing_buffer(void){
2058     uint8_t * rfcomm_out_buffer = l2cap_get_outgoing_buffer();
2059     // address + control + length (16) + no credit field
2060     return &rfcomm_out_buffer[4];
2061 }
2062 
2063 uint16_t rfcomm_get_max_frame_size(uint16_t rfcomm_cid){
2064     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2065     if (!channel){
2066         log_error("rfcomm_get_max_frame_size cid 0x%02x doesn't exist!", rfcomm_cid);
2067         return 0;
2068     }
2069     return channel->max_frame_size;
2070 }
2071 int rfcomm_send_prepared(uint16_t rfcomm_cid, uint16_t len){
2072     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2073     if (!channel){
2074         log_error("rfcomm_send_prepared cid 0x%02x doesn't exist!", rfcomm_cid);
2075         return 0;
2076     }
2077 
2078     int err = rfcomm_assert_send_valid(channel, len);
2079     if (err) return err;
2080 
2081     // send might cause l2cap to emit new credits, update counters first
2082     channel->credits_outgoing--;
2083     int packets_granted_decreased = 0;
2084     if (channel->packets_granted) {
2085         channel->packets_granted--;
2086         packets_granted_decreased++;
2087     }
2088 
2089     int result = rfcomm_send_uih_prepared(channel->multiplexer, channel->dlci, len);
2090 
2091     if (result != 0) {
2092         channel->credits_outgoing++;
2093         channel->packets_granted += packets_granted_decreased;
2094         log_info("rfcomm_send_internal: error %d", result);
2095         return result;
2096     }
2097 
2098     rfcomm_hand_out_credits();
2099 
2100     return result;
2101 }
2102 
2103 int rfcomm_send_internal(uint16_t rfcomm_cid, uint8_t *data, uint16_t len){
2104     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2105     if (!channel){
2106         log_error("rfcomm_send_internal cid 0x%02x doesn't exist!", rfcomm_cid);
2107         return 1;
2108     }
2109 
2110     int err = rfcomm_assert_send_valid(channel, len);
2111     if (err) return err;
2112 
2113     rfcomm_reserve_packet_buffer();
2114     uint8_t * rfcomm_payload = rfcomm_get_outgoing_buffer();
2115     memcpy(rfcomm_payload, data, len);
2116     return rfcomm_send_prepared(rfcomm_cid, len);
2117 }
2118 
2119 // Sends Local Lnie Status, see LINE_STATUS_..
2120 int rfcomm_send_local_line_status(uint16_t rfcomm_cid, uint8_t line_status){
2121     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2122     if (!channel){
2123         log_error("rfcomm_send_local_line_status cid 0x%02x doesn't exist!", rfcomm_cid);
2124         return 0;
2125     }
2126     return rfcomm_send_uih_rls_cmd(channel->multiplexer, channel->dlci, line_status);
2127 }
2128 
2129 // Sned local modem status. see MODEM_STAUS_..
2130 int rfcomm_send_modem_status(uint16_t rfcomm_cid, uint8_t modem_status){
2131     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2132     if (!channel){
2133         log_error("rfcomm_send_modem_status cid 0x%02x doesn't exist!", rfcomm_cid);
2134         return 0;
2135     }
2136     return rfcomm_send_uih_msc_cmd(channel->multiplexer, channel->dlci, modem_status);
2137 }
2138 
2139 // Configure remote port
2140 int rfcomm_send_port_configuration(uint16_t rfcomm_cid, rpn_baud_t baud_rate, rpn_data_bits_t data_bits, rpn_stop_bits_t stop_bits, rpn_parity_t parity, rpn_flow_control_t flow_control){
2141     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2142     if (!channel){
2143         log_error("rfcomm_send_port_configuration cid 0x%02x doesn't exist!", rfcomm_cid);
2144         return 0;
2145     }
2146     rfcomm_rpn_data_t rpn_data;
2147     rpn_data.baud_rate = baud_rate;
2148     rpn_data.flags = data_bits | (stop_bits << 2) | (parity << 3);
2149     rpn_data.flow_control = flow_control;
2150     rpn_data.xon = 0;
2151     rpn_data.xoff = 0;
2152     rpn_data.parameter_mask_0 = 0x1f;   // all but xon/xoff
2153     rpn_data.parameter_mask_1 = 0x3f;   // all flow control options
2154     return rfcomm_send_uih_rpn_cmd(channel->multiplexer, channel->dlci, &rpn_data);
2155 }
2156 
2157 // Query remote port
2158 int rfcomm_query_port_configuration(uint16_t rfcomm_cid){
2159     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2160     if (!channel){
2161         log_error("rfcomm_query_port_configuration cid 0x%02x doesn't exist!", rfcomm_cid);
2162         return 0;
2163     }
2164     return rfcomm_send_uih_rpn_req(channel->multiplexer, channel->dlci);
2165 }
2166 
2167 static uint8_t rfcomm_create_channel_internal(bd_addr_t addr, uint8_t server_channel, uint8_t incoming_flow_control, uint8_t initial_credits, uint16_t * out_rfcomm_cid){
2168     log_info("RFCOMM_CREATE_CHANNEL addr %s channel #%u init credits %u",  bd_addr_to_str(addr), server_channel, initial_credits);
2169 
2170     // create new multiplexer if necessary
2171     uint8_t status = 0;
2172     int new_multiplexer = 0;
2173     rfcomm_channel_t * channel = NULL;
2174     rfcomm_multiplexer_t * multiplexer = rfcomm_multiplexer_for_addr(addr);
2175     if (!multiplexer) {
2176         multiplexer = rfcomm_multiplexer_create_for_addr(addr);
2177         if (!multiplexer){
2178             status = BTSTACK_MEMORY_ALLOC_FAILED;
2179             goto fail;
2180         }
2181         multiplexer->outgoing = 1;
2182         multiplexer->state = RFCOMM_MULTIPLEXER_W4_CONNECT;
2183         new_multiplexer = 1;
2184     }
2185 
2186     // prepare channel
2187     channel = rfcomm_channel_create(multiplexer, NULL, server_channel);
2188     if (!channel){
2189         status = BTSTACK_MEMORY_ALLOC_FAILED;
2190         goto fail;
2191     }
2192     // rfcomm_cid is already assigned by rfcomm_channel_create
2193     channel->incoming_flow_control = incoming_flow_control;
2194     channel->new_credits_incoming  = initial_credits;
2195 
2196     // return rfcomm_cid
2197     if (out_rfcomm_cid){
2198         *out_rfcomm_cid = channel->rfcomm_cid;
2199     }
2200 
2201     // start multiplexer setup
2202     if (multiplexer->state != RFCOMM_MULTIPLEXER_OPEN) {
2203         channel->state = RFCOMM_CHANNEL_W4_MULTIPLEXER;
2204         uint16_t l2cap_cid = 0;
2205         status = l2cap_create_channel(rfcomm_packet_handler, addr, PSM_RFCOMM, l2cap_max_mtu(), &l2cap_cid);
2206         if (status) goto fail;
2207         multiplexer->l2cap_cid = l2cap_cid;
2208         return 0;
2209     }
2210 
2211     channel->state = RFCOMM_CHANNEL_SEND_UIH_PN;
2212 
2213     // start connecting, if multiplexer is already up and running
2214     rfcomm_run();
2215     return 0;
2216 
2217 fail:
2218     if (new_multiplexer) btstack_memory_rfcomm_multiplexer_free(multiplexer);
2219     if (channel)         btstack_memory_rfcomm_channel_free(channel);
2220     return status;
2221 }
2222 
2223 uint8_t rfcomm_create_channel_with_initial_credits(bd_addr_t addr, uint8_t server_channel, uint8_t initial_credits, uint16_t * out_rfcomm_cid){
2224     return rfcomm_create_channel_internal(addr, server_channel, 1, initial_credits, out_rfcomm_cid);
2225 }
2226 
2227 uint8_t rfcomm_create_channel(bd_addr_t addr, uint8_t server_channel, uint16_t * out_rfcomm_cid){
2228     return rfcomm_create_channel_internal(addr, server_channel, 0, RFCOMM_CREDITS, out_rfcomm_cid);
2229 }
2230 
2231 void rfcomm_disconnect_internal(uint16_t rfcomm_cid){
2232     log_info("RFCOMM_DISCONNECT cid 0x%02x", rfcomm_cid);
2233     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2234     if (channel) {
2235         channel->state = RFCOMM_CHANNEL_SEND_DISC;
2236     }
2237 
2238     // process
2239     rfcomm_run();
2240 }
2241 
2242 static void rfcomm_register_service2(void * connection, uint8_t channel, uint16_t max_frame_size, uint8_t incoming_flow_control, uint8_t initial_credits){
2243     log_info("RFCOMM_REGISTER_SERVICE channel #%u mtu %u flow_control %u credits %u",
2244              channel, max_frame_size, incoming_flow_control, initial_credits);
2245     // check if already registered
2246     rfcomm_service_t * service = rfcomm_service_for_channel(channel);
2247     if (service){
2248         rfcomm_emit_service_registered(connection, RFCOMM_CHANNEL_ALREADY_REGISTERED, channel);
2249         return;
2250     }
2251 
2252     // alloc structure
2253     service = btstack_memory_rfcomm_service_get();
2254     if (!service) {
2255         rfcomm_emit_service_registered(connection, BTSTACK_MEMORY_ALLOC_FAILED, channel);
2256         return;
2257     }
2258 
2259     // register with l2cap if not registered before, max MTU
2260     if (linked_list_empty(&rfcomm_services)){
2261         l2cap_register_service(rfcomm_packet_handler, PSM_RFCOMM, 0xffff, rfcomm_security_level);
2262     }
2263 
2264     // fill in
2265     service->connection     = connection;
2266     service->server_channel = channel;
2267     service->max_frame_size = max_frame_size;
2268     service->incoming_flow_control = incoming_flow_control;
2269     service->incoming_initial_credits = initial_credits;
2270 
2271     // add to services list
2272     linked_list_add(&rfcomm_services, (linked_item_t *) service);
2273 
2274     // done
2275     rfcomm_emit_service_registered(connection, 0, channel);
2276 }
2277 
2278 void rfcomm_register_service_with_initial_credits_internal(void * connection, uint8_t channel, uint16_t max_frame_size, uint8_t initial_credits){
2279     rfcomm_register_service2(connection, channel, max_frame_size, 1, initial_credits);
2280 }
2281 
2282 void rfcomm_register_service_internal(void * connection, uint8_t channel, uint16_t max_frame_size){
2283     rfcomm_register_service2(connection, channel, max_frame_size, 0,RFCOMM_CREDITS);
2284 }
2285 
2286 void rfcomm_unregister_service_internal(uint8_t service_channel){
2287     log_info("RFCOMM_UNREGISTER_SERVICE #%u", service_channel);
2288     rfcomm_service_t *service = rfcomm_service_for_channel(service_channel);
2289     if (!service) return;
2290     linked_list_remove(&rfcomm_services, (linked_item_t *) service);
2291     btstack_memory_rfcomm_service_free(service);
2292 
2293     // unregister if no services active
2294     if (linked_list_empty(&rfcomm_services)){
2295         // bt_send_cmd(&l2cap_unregister_service, PSM_RFCOMM);
2296         l2cap_unregister_service(PSM_RFCOMM);
2297     }
2298 }
2299 
2300 void rfcomm_accept_connection_internal(uint16_t rfcomm_cid){
2301     log_info("RFCOMM_ACCEPT_CONNECTION cid 0x%02x", rfcomm_cid);
2302     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2303     if (!channel) return;
2304     switch (channel->state) {
2305         case RFCOMM_CHANNEL_INCOMING_SETUP:
2306             rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_CLIENT_ACCEPTED);
2307             if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_RCVD_PN){
2308                 rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_PN_RSP);
2309             }
2310             if (channel->state_var & RFCOMM_CHANNEL_STATE_VAR_RCVD_SABM){
2311                 rfcomm_channel_state_add(channel, RFCOMM_CHANNEL_STATE_VAR_SEND_UA);
2312             }
2313             // at least one of { PN RSP, UA } needs to be sent
2314             // state transistion incoming setup -> dlc setup happens in rfcomm_run after these have been sent
2315             break;
2316         default:
2317             break;
2318     }
2319 
2320     // process
2321     rfcomm_run();
2322 }
2323 
2324 void rfcomm_decline_connection_internal(uint16_t rfcomm_cid){
2325     log_info("RFCOMM_DECLINE_CONNECTION cid 0x%02x", rfcomm_cid);
2326     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2327     if (!channel) return;
2328     switch (channel->state) {
2329         case RFCOMM_CHANNEL_INCOMING_SETUP:
2330             channel->state = RFCOMM_CHANNEL_SEND_DM;
2331             break;
2332         default:
2333             break;
2334     }
2335 
2336     // process
2337     rfcomm_run();
2338 }
2339 
2340 void rfcomm_grant_credits(uint16_t rfcomm_cid, uint8_t credits){
2341     log_info("RFCOMM_GRANT_CREDITS cid 0x%02x credits %u", rfcomm_cid, credits);
2342     rfcomm_channel_t * channel = rfcomm_channel_for_rfcomm_cid(rfcomm_cid);
2343     if (!channel) return;
2344     if (!channel->incoming_flow_control) return;
2345     channel->new_credits_incoming += credits;
2346 
2347     // process
2348     rfcomm_run();
2349 }
2350 
2351 
2352 
2353 
2354