1 /******************************************************************************
2  *
3  *  Copyright 2004-2012 Broadcom Corporation
4  *
5  *  Licensed under the Apache License, Version 2.0 (the "License");
6  *  you may not use this file except in compliance with the License.
7  *  You may obtain a copy of the License at:
8  *
9  *  http://www.apache.org/licenses/LICENSE-2.0
10  *
11  *  Unless required by applicable law or agreed to in writing, software
12  *  distributed under the License is distributed on an "AS IS" BASIS,
13  *  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14  *  See the License for the specific language governing permissions and
15  *  limitations under the License.
16  *
17  ******************************************************************************/
18 
19 /******************************************************************************
20  *
21  *  This file contains the L2CAP 1.2 Flow Control and retransmissions
22  *  functions
23  *
24  ******************************************************************************/
25 
26 #include <base/logging.h>
27 #include <log/log.h>
28 #include <stdio.h>
29 #include <stdlib.h>
30 #include <string.h>
31 
32 #include "bt_common.h"
33 #include "bt_types.h"
34 #include "btu.h"
35 #include "common/time_util.h"
36 #include "hcimsgs.h"
37 #include "l2c_api.h"
38 #include "l2c_int.h"
39 #include "l2cdefs.h"
40 
41 /* Flag passed to retransmit_i_frames() when all packets should be retransmitted
42  */
43 #define L2C_FCR_RETX_ALL_PKTS 0xFF
44 
45 /* this is the minimal offset required by OBX to process incoming packets */
46 static const uint16_t OBX_BUF_MIN_OFFSET = 4;
47 
48 static const char* SAR_types[] = {"Unsegmented", "Start", "End",
49                                   "Continuation"};
50 static const char* SUP_types[] = {"RR", "REJ", "RNR", "SREJ"};
51 
52 /* Look-up table for the CRC calculation */
53 static const unsigned short crctab[256] = {
54     0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241, 0xc601,
55     0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440, 0xcc01, 0x0cc0,
56     0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40, 0x0a00, 0xcac1, 0xcb81,
57     0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841, 0xd801, 0x18c0, 0x1980, 0xd941,
58     0x1b00, 0xdbc1, 0xda81, 0x1a40, 0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01,
59     0x1dc0, 0x1c80, 0xdc41, 0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0,
60     0x1680, 0xd641, 0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081,
61     0x1040, 0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
62     0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441, 0x3c00,
63     0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41, 0xfa01, 0x3ac0,
64     0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840, 0x2800, 0xe8c1, 0xe981,
65     0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41, 0xee01, 0x2ec0, 0x2f80, 0xef41,
66     0x2d00, 0xedc1, 0xec81, 0x2c40, 0xe401, 0x24c0, 0x2580, 0xe541, 0x2700,
67     0xe7c1, 0xe681, 0x2640, 0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0,
68     0x2080, 0xe041, 0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281,
69     0x6240, 0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
70     0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41, 0xaa01,
71     0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840, 0x7800, 0xb8c1,
72     0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41, 0xbe01, 0x7ec0, 0x7f80,
73     0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40, 0xb401, 0x74c0, 0x7580, 0xb541,
74     0x7700, 0xb7c1, 0xb681, 0x7640, 0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101,
75     0x71c0, 0x7080, 0xb041, 0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0,
76     0x5280, 0x9241, 0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481,
77     0x5440, 0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
78     0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841, 0x8801,
79     0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40, 0x4e00, 0x8ec1,
80     0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41, 0x4400, 0x84c1, 0x8581,
81     0x4540, 0x8701, 0x47c0, 0x4680, 0x8641, 0x8201, 0x42c0, 0x4380, 0x8341,
82     0x4100, 0x81c1, 0x8081, 0x4040,
83 };
84 
85 /*******************************************************************************
86  *  Static local functions
87 */
88 static bool process_reqseq(tL2C_CCB* p_ccb, uint16_t ctrl_word);
89 static void process_s_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf, uint16_t ctrl_word);
90 static void process_i_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf, uint16_t ctrl_word,
91                             bool delay_ack);
92 static bool retransmit_i_frames(tL2C_CCB* p_ccb, uint8_t tx_seq);
93 static void prepare_I_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf,
94                             bool is_retransmission);
95 static void process_stream_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf);
96 static bool do_sar_reassembly(tL2C_CCB* p_ccb, BT_HDR* p_buf,
97                               uint16_t ctrl_word);
98 
99 #if (L2CAP_ERTM_STATS == TRUE)
100 static void l2c_fcr_collect_ack_delay(tL2C_CCB* p_ccb, uint8_t num_bufs_acked);
101 #endif
102 
103 /*******************************************************************************
104  *
105  * Function         l2c_fcr_updcrc
106  *
107  * Description      This function computes the CRC using the look-up table.
108  *
109  * Returns          CRC
110  *
111  ******************************************************************************/
l2c_fcr_updcrc(unsigned short icrc,unsigned char * icp,int icnt)112 static unsigned short l2c_fcr_updcrc(unsigned short icrc, unsigned char* icp,
113                                      int icnt) {
114   unsigned short crc = icrc;
115   unsigned char* cp = icp;
116   int cnt = icnt;
117 
118   while (cnt--) {
119     crc = ((crc >> 8) & 0xff) ^ crctab[(crc & 0xff) ^ *cp++];
120   }
121 
122   return (crc);
123 }
124 
125 /*******************************************************************************
126  *
127  * Function         l2c_fcr_tx_get_fcs
128  *
129  * Description      This function computes the CRC for a frame to be TXed.
130  *
131  * Returns          CRC
132  *
133  ******************************************************************************/
l2c_fcr_tx_get_fcs(BT_HDR * p_buf)134 static uint16_t l2c_fcr_tx_get_fcs(BT_HDR* p_buf) {
135   uint8_t* p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
136 
137   return (l2c_fcr_updcrc(L2CAP_FCR_INIT_CRC, p, p_buf->len));
138 }
139 
140 /*******************************************************************************
141  *
142  * Function         l2c_fcr_rx_get_fcs
143  *
144  * Description      This function computes the CRC for a received frame.
145  *
146  * Returns          CRC
147  *
148  ******************************************************************************/
l2c_fcr_rx_get_fcs(BT_HDR * p_buf)149 static uint16_t l2c_fcr_rx_get_fcs(BT_HDR* p_buf) {
150   uint8_t* p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
151 
152   /* offset points past the L2CAP header, but the CRC check includes it */
153   p -= L2CAP_PKT_OVERHEAD;
154 
155   return (
156       l2c_fcr_updcrc(L2CAP_FCR_INIT_CRC, p, p_buf->len + L2CAP_PKT_OVERHEAD));
157 }
158 
159 /*******************************************************************************
160  *
161  * Function         l2c_fcr_start_timer
162  *
163  * Description      This function starts the (monitor or retransmission) timer.
164  *
165  * Returns          -
166  *
167  ******************************************************************************/
l2c_fcr_start_timer(tL2C_CCB * p_ccb)168 void l2c_fcr_start_timer(tL2C_CCB* p_ccb) {
169   CHECK(p_ccb != NULL);
170   uint32_t tout;
171 
172   /* The timers which are in milliseconds */
173   if (p_ccb->fcrb.wait_ack) {
174     tout = (uint32_t)p_ccb->our_cfg.fcr.mon_tout;
175   } else {
176     tout = (uint32_t)p_ccb->our_cfg.fcr.rtrans_tout;
177   }
178 
179   /* Only start a timer that was not started */
180   if (!alarm_is_scheduled(p_ccb->fcrb.mon_retrans_timer)) {
181     alarm_set_on_mloop(p_ccb->fcrb.mon_retrans_timer, tout,
182                        l2c_ccb_timer_timeout, p_ccb);
183   }
184 }
185 
186 /*******************************************************************************
187  *
188  * Function         l2c_fcr_stop_timer
189  *
190  * Description      This function stops the (monitor or transmission) timer.
191  *
192  * Returns          -
193  *
194  ******************************************************************************/
l2c_fcr_stop_timer(tL2C_CCB * p_ccb)195 void l2c_fcr_stop_timer(tL2C_CCB* p_ccb) {
196   CHECK(p_ccb != NULL);
197   alarm_cancel(p_ccb->fcrb.mon_retrans_timer);
198 }
199 
200 /*******************************************************************************
201  *
202  * Function         l2c_fcr_cleanup
203  *
204  * Description      This function cleans up the variable used for
205  *                  flow-control/retrans.
206  *
207  * Returns          -
208  *
209  ******************************************************************************/
l2c_fcr_cleanup(tL2C_CCB * p_ccb)210 void l2c_fcr_cleanup(tL2C_CCB* p_ccb) {
211   CHECK(p_ccb != NULL);
212   tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
213 
214   alarm_free(p_fcrb->mon_retrans_timer);
215   p_fcrb->mon_retrans_timer = NULL;
216   alarm_free(p_fcrb->ack_timer);
217   p_fcrb->ack_timer = NULL;
218 
219   osi_free_and_reset((void**)&p_fcrb->p_rx_sdu);
220 
221   fixed_queue_free(p_fcrb->waiting_for_ack_q, osi_free);
222   p_fcrb->waiting_for_ack_q = NULL;
223 
224   fixed_queue_free(p_fcrb->srej_rcv_hold_q, osi_free);
225   p_fcrb->srej_rcv_hold_q = NULL;
226 
227   fixed_queue_free(p_fcrb->retrans_q, osi_free);
228   p_fcrb->retrans_q = NULL;
229 
230 #if (L2CAP_ERTM_STATS == TRUE)
231   if ((p_ccb->local_cid >= L2CAP_BASE_APPL_CID) &&
232       (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE)) {
233     uint64_t dur = bluetooth::common::time_get_os_boottime_ms() -
234                    p_ccb->fcrb.connect_tick_count;
235     size_t p_str_size = 120;
236     char* p_str = (char*)osi_malloc(p_str_size);
237     uint16_t i;
238     uint32_t throughput_avg, ack_delay_avg, ack_q_count_avg;
239 
240     BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
241              TRACE_TYPE_GENERIC,
242              "---  L2CAP ERTM  Stats for CID: 0x%04x   Duration: %08ums",
243              p_ccb->local_cid, dur);
244     BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
245              TRACE_TYPE_GENERIC,
246              "Retransmissions:%08u Times Flow Controlled:%08u Retrans "
247              "Touts:%08u Ack Touts:%08u",
248              p_ccb->fcrb.pkts_retransmitted, p_ccb->fcrb.xmit_window_closed,
249              p_ccb->fcrb.retrans_touts, p_ccb->fcrb.xmit_ack_touts);
250     BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
251              TRACE_TYPE_GENERIC,
252              "Times there is less than 2 packets in controller when flow "
253              "controlled:%08u",
254              p_ccb->fcrb.controller_idle);
255     BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
256              TRACE_TYPE_GENERIC,
257              "max_held_acks:%08u, in_cfg.fcr.tx_win_sz:%08u",
258              p_ccb->fcrb.max_held_acks, p_ccb->peer_cfg.fcr.tx_win_sz);
259 
260     snprintf(
261         p_str, p_str_size,
262         "Sent Pkts:%08u Bytes:%10u(%06u/sec) RR:%08u REJ:%08u RNR:%08u "
263         "SREJ:%08u",
264         p_ccb->fcrb.ertm_pkt_counts[0], p_ccb->fcrb.ertm_byte_counts[0],
265         (dur >= 10 ? (p_ccb->fcrb.ertm_byte_counts[0] * 100) / (dur / 10) : 0),
266         p_ccb->fcrb.s_frames_sent[0], p_ccb->fcrb.s_frames_sent[1],
267         p_ccb->fcrb.s_frames_sent[2], p_ccb->fcrb.s_frames_sent[3]);
268 
269     BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
270              TRACE_TYPE_GENERIC, "%s", p_str);
271 
272     snprintf(
273         p_str, p_str_size,
274         "Rcvd Pkts:%08u Bytes:%10u(%06u/sec) RR:%08u REJ:%08u RNR:%08u "
275         "SREJ:%08u",
276         p_ccb->fcrb.ertm_pkt_counts[1], p_ccb->fcrb.ertm_byte_counts[1],
277         (dur >= 10 ? (p_ccb->fcrb.ertm_byte_counts[1] * 100) / (dur / 10) : 0),
278         p_ccb->fcrb.s_frames_rcvd[0], p_ccb->fcrb.s_frames_rcvd[1],
279         p_ccb->fcrb.s_frames_rcvd[2], p_ccb->fcrb.s_frames_rcvd[3]);
280 
281     BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
282              TRACE_TYPE_GENERIC, "%s", p_str);
283 
284     throughput_avg = 0;
285     ack_delay_avg = 0;
286     ack_q_count_avg = 0;
287 
288     for (i = 0; i < L2CAP_ERTM_STATS_NUM_AVG; i++) {
289       if (i == p_ccb->fcrb.ack_delay_avg_index) {
290         BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
291                  TRACE_TYPE_GENERIC, "[%02u] collecting data ...", i);
292         continue;
293       }
294 
295       snprintf(p_str, p_str_size,
296                "[%02u] throughput: %5u, ack_delay avg:%3u, min:%3u, max:%3u, "
297                "ack_q_count avg:%3u, min:%3u, max:%3u",
298                i, p_ccb->fcrb.throughput[i], p_ccb->fcrb.ack_delay_avg[i],
299                p_ccb->fcrb.ack_delay_min[i], p_ccb->fcrb.ack_delay_max[i],
300                p_ccb->fcrb.ack_q_count_avg[i], p_ccb->fcrb.ack_q_count_min[i],
301                p_ccb->fcrb.ack_q_count_max[i]);
302 
303       BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
304                TRACE_TYPE_GENERIC, "%s", p_str);
305 
306       throughput_avg += p_ccb->fcrb.throughput[i];
307       ack_delay_avg += p_ccb->fcrb.ack_delay_avg[i];
308       ack_q_count_avg += p_ccb->fcrb.ack_q_count_avg[i];
309     }
310 
311     throughput_avg /= (L2CAP_ERTM_STATS_NUM_AVG - 1);
312     ack_delay_avg /= (L2CAP_ERTM_STATS_NUM_AVG - 1);
313     ack_q_count_avg /= (L2CAP_ERTM_STATS_NUM_AVG - 1);
314 
315     BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
316              TRACE_TYPE_GENERIC,
317              "throughput_avg: %8u (kbytes/sec), ack_delay_avg: %8u ms, "
318              "ack_q_count_avg: %8u",
319              throughput_avg, ack_delay_avg, ack_q_count_avg);
320 
321     osi_free(p_str);
322 
323     BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
324              TRACE_TYPE_GENERIC, "---");
325   }
326 #endif
327 
328   memset(p_fcrb, 0, sizeof(tL2C_FCRB));
329 }
330 
331 /*******************************************************************************
332  *
333  * Function         l2c_fcr_clone_buf
334  *
335  * Description      This function allocates and copies requested part of a
336  *                  buffer at a new-offset.
337  *
338  * Returns          pointer to new buffer
339  *
340  ******************************************************************************/
l2c_fcr_clone_buf(BT_HDR * p_buf,uint16_t new_offset,uint16_t no_of_bytes)341 BT_HDR* l2c_fcr_clone_buf(BT_HDR* p_buf, uint16_t new_offset,
342                           uint16_t no_of_bytes) {
343   CHECK(p_buf != NULL);
344   /*
345    * NOTE: We allocate extra L2CAP_FCS_LEN octets, in case we need to put
346    * the FCS (Frame Check Sequence) at the end of the buffer.
347    */
348   uint16_t buf_size = no_of_bytes + sizeof(BT_HDR) + new_offset + L2CAP_FCS_LEN;
349 #if (L2CAP_ERTM_STATS == TRUE)
350   /*
351    * NOTE: If L2CAP_ERTM_STATS is enabled, we need 4 extra octets at the
352    * end for a timestamp at the end of an I-frame.
353    */
354   buf_size += sizeof(uint32_t);
355 #endif
356   BT_HDR* p_buf2 = (BT_HDR*)osi_malloc(buf_size);
357 
358   p_buf2->offset = new_offset;
359   p_buf2->len = no_of_bytes;
360   memcpy(((uint8_t*)(p_buf2 + 1)) + p_buf2->offset,
361          ((uint8_t*)(p_buf + 1)) + p_buf->offset, no_of_bytes);
362 
363   return (p_buf2);
364 }
365 
366 /*******************************************************************************
367  *
368  * Function         l2c_fcr_is_flow_controlled
369  *
370  * Description      This function checks if the CCB is flow controlled by peer.
371  *
372  * Returns          The control word
373  *
374  ******************************************************************************/
l2c_fcr_is_flow_controlled(tL2C_CCB * p_ccb)375 bool l2c_fcr_is_flow_controlled(tL2C_CCB* p_ccb) {
376   CHECK(p_ccb != NULL);
377   if (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE) {
378     /* Check if remote side flowed us off or the transmit window is full */
379     if ((p_ccb->fcrb.remote_busy) ||
380         (fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q) >=
381          p_ccb->peer_cfg.fcr.tx_win_sz)) {
382 #if (L2CAP_ERTM_STATS == TRUE)
383       if (!fixed_queue_is_empty(p_ccb->xmit_hold_q)) {
384         p_ccb->fcrb.xmit_window_closed++;
385 
386         if ((p_ccb->p_lcb->sent_not_acked < 2) &&
387             (l2cb.controller_xmit_window > 0))
388           p_ccb->fcrb.controller_idle++;
389       }
390 #endif
391       return (true);
392     }
393   }
394   return (false);
395 }
396 
397 /*******************************************************************************
398  *
399  * Function         prepare_I_frame
400  *
401  * Description      This function sets the FCR variables in an I-frame that is
402  *                  about to be sent to HCI for transmission. This may be the
403  *                  first time the I-frame is sent, or a retransmission
404  *
405  * Returns          -
406  *
407  ******************************************************************************/
prepare_I_frame(tL2C_CCB * p_ccb,BT_HDR * p_buf,bool is_retransmission)408 static void prepare_I_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf,
409                             bool is_retransmission) {
410   CHECK(p_ccb != NULL);
411   CHECK(p_buf != NULL);
412   tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
413   uint8_t* p;
414   uint16_t fcs;
415   uint16_t ctrl_word;
416   bool set_f_bit = p_fcrb->send_f_rsp;
417 
418   p_fcrb->send_f_rsp = false;
419 
420   if (is_retransmission) {
421     /* Get the old control word and clear out the old req_seq and F bits */
422     p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + L2CAP_PKT_OVERHEAD;
423 
424     STREAM_TO_UINT16(ctrl_word, p);
425 
426     ctrl_word &= ~(L2CAP_FCR_REQ_SEQ_BITS + L2CAP_FCR_F_BIT);
427   } else {
428     ctrl_word = p_buf->layer_specific & L2CAP_FCR_SEG_BITS; /* SAR bits */
429     ctrl_word |=
430         (p_fcrb->next_tx_seq << L2CAP_FCR_TX_SEQ_BITS_SHIFT); /* Tx Seq */
431 
432     p_fcrb->next_tx_seq = (p_fcrb->next_tx_seq + 1) & L2CAP_FCR_SEQ_MODULO;
433   }
434 
435   /* Set the F-bit and reqseq only if using re-transmission mode */
436   if (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE) {
437     if (set_f_bit) ctrl_word |= L2CAP_FCR_F_BIT;
438 
439     ctrl_word |= (p_fcrb->next_seq_expected) << L2CAP_FCR_REQ_SEQ_BITS_SHIFT;
440 
441     p_fcrb->last_ack_sent = p_ccb->fcrb.next_seq_expected;
442 
443     alarm_cancel(p_ccb->fcrb.ack_timer);
444   }
445 
446   /* Set the control word */
447   p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + L2CAP_PKT_OVERHEAD;
448 
449   UINT16_TO_STREAM(p, ctrl_word);
450 
451   /* Compute the FCS and add to the end of the buffer if not bypassed */
452   if (p_ccb->bypass_fcs != L2CAP_BYPASS_FCS) {
453     /* length field in l2cap header has to include FCS length */
454     p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
455     UINT16_TO_STREAM(p, p_buf->len + L2CAP_FCS_LEN - L2CAP_PKT_OVERHEAD);
456 
457     /* Calculate the FCS */
458     fcs = l2c_fcr_tx_get_fcs(p_buf);
459 
460     /* Point to the end of the buffer and put the FCS there */
461     /*
462      * NOTE: Here we assume the allocated buffer is large enough
463      * to include extra L2CAP_FCS_LEN octets at the end.
464      */
465     p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + p_buf->len;
466 
467     UINT16_TO_STREAM(p, fcs);
468 
469     p_buf->len += L2CAP_FCS_LEN;
470   }
471 
472   if (is_retransmission) {
473     L2CAP_TRACE_EVENT(
474         "L2CAP eRTM ReTx I-frame  CID: 0x%04x  Len: %u  SAR: %s  TxSeq: %u  "
475         "ReqSeq: %u  F: %u",
476         p_ccb->local_cid, p_buf->len,
477         SAR_types[(ctrl_word & L2CAP_FCR_SAR_BITS) >> L2CAP_FCR_SAR_BITS_SHIFT],
478         (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT,
479         (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
480         (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
481   } else {
482     L2CAP_TRACE_EVENT(
483         "L2CAP eRTM Tx I-frame CID: 0x%04x  Len: %u  SAR: %-12s  TxSeq: %u  "
484         "ReqSeq: %u  F: %u",
485         p_ccb->local_cid, p_buf->len,
486         SAR_types[(ctrl_word & L2CAP_FCR_SAR_BITS) >> L2CAP_FCR_SAR_BITS_SHIFT],
487         (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT,
488         (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
489         (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
490   }
491 
492   /* Start the retransmission timer if not already running */
493   if (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE)
494     l2c_fcr_start_timer(p_ccb);
495 }
496 
497 /*******************************************************************************
498  *
499  * Function         l2c_fcr_send_S_frame
500  *
501  * Description      This function formats and sends an S-frame for transmission.
502  *
503  * Returns          -
504  *
505  ******************************************************************************/
l2c_fcr_send_S_frame(tL2C_CCB * p_ccb,uint16_t function_code,uint16_t pf_bit)506 void l2c_fcr_send_S_frame(tL2C_CCB* p_ccb, uint16_t function_code,
507                           uint16_t pf_bit) {
508   CHECK(p_ccb != NULL);
509   uint8_t* p;
510   uint16_t ctrl_word;
511   uint16_t fcs;
512 
513   if ((!p_ccb->in_use) || (p_ccb->chnl_state != CST_OPEN)) return;
514 
515 #if (L2CAP_ERTM_STATS == TRUE)
516   p_ccb->fcrb.s_frames_sent[function_code]++;
517 #endif
518 
519   if (pf_bit == L2CAP_FCR_P_BIT) {
520     p_ccb->fcrb.wait_ack = true;
521 
522     l2c_fcr_stop_timer(p_ccb); /* Restart the monitor timer */
523     l2c_fcr_start_timer(p_ccb);
524   }
525 
526   /* Create the control word to use */
527   ctrl_word = (function_code << L2CAP_FCR_SUP_SHIFT) | L2CAP_FCR_S_FRAME_BIT;
528   ctrl_word |= (p_ccb->fcrb.next_seq_expected << L2CAP_FCR_REQ_SEQ_BITS_SHIFT);
529   ctrl_word |= pf_bit;
530 
531   BT_HDR* p_buf = (BT_HDR*)osi_malloc(L2CAP_CMD_BUF_SIZE);
532   p_buf->offset = HCI_DATA_PREAMBLE_SIZE;
533   p_buf->len = L2CAP_PKT_OVERHEAD + L2CAP_FCR_OVERHEAD;
534 
535   /* Set the pointer to the beginning of the data */
536   p = (uint8_t*)(p_buf + 1) + p_buf->offset;
537 
538   /* Put in the L2CAP header */
539   UINT16_TO_STREAM(p, L2CAP_FCR_OVERHEAD + L2CAP_FCS_LEN);
540   UINT16_TO_STREAM(p, p_ccb->remote_cid);
541   UINT16_TO_STREAM(p, ctrl_word);
542 
543   /* Compute the FCS and add to the end of the buffer if not bypassed */
544   if (p_ccb->bypass_fcs != L2CAP_BYPASS_FCS) {
545     fcs = l2c_fcr_tx_get_fcs(p_buf);
546 
547     UINT16_TO_STREAM(p, fcs);
548     p_buf->len += L2CAP_FCS_LEN;
549   } else {
550     /* rewrite the length without FCS length */
551     p -= 6;
552     UINT16_TO_STREAM(p, L2CAP_FCR_OVERHEAD);
553   }
554 
555   /* Now, the HCI transport header */
556   p_buf->layer_specific = L2CAP_NON_FLUSHABLE_PKT;
557   l2cu_set_acl_hci_header(p_buf, p_ccb);
558 
559   if ((((ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT) == 1) ||
560       (((ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT) == 3)) {
561     L2CAP_TRACE_WARNING(
562         "L2CAP eRTM Tx S-frame  CID: 0x%04x  ctrlword: 0x%04x  Type: %s  "
563         "ReqSeq: %u  P: %u  F: %u",
564         p_ccb->local_cid, ctrl_word,
565         SUP_types[(ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT],
566         (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
567         (ctrl_word & L2CAP_FCR_P_BIT) >> L2CAP_FCR_P_BIT_SHIFT,
568         (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
569     L2CAP_TRACE_WARNING("                  Buf Len: %u", p_buf->len);
570   } else {
571     L2CAP_TRACE_EVENT(
572         "L2CAP eRTM Tx S-frame  CID: 0x%04x  ctrlword: 0x%04x  Type: %s  "
573         "ReqSeq: %u  P: %u  F: %u",
574         p_ccb->local_cid, ctrl_word,
575         SUP_types[(ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT],
576         (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
577         (ctrl_word & L2CAP_FCR_P_BIT) >> L2CAP_FCR_P_BIT_SHIFT,
578         (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
579     L2CAP_TRACE_EVENT("                  Buf Len: %u", p_buf->len);
580   }
581 
582   l2c_link_check_send_pkts(p_ccb->p_lcb, NULL, p_buf);
583 
584   p_ccb->fcrb.last_ack_sent = p_ccb->fcrb.next_seq_expected;
585 
586   alarm_cancel(p_ccb->fcrb.ack_timer);
587 }
588 
589 /*******************************************************************************
590  *
591  * Function         l2c_fcr_proc_pdu
592  *
593  * Description      This function is the entry point for processing of a
594  *                  received PDU when in flow control and/or retransmission
595  *                  modes.
596  *
597  * Returns          -
598  *
599  ******************************************************************************/
l2c_fcr_proc_pdu(tL2C_CCB * p_ccb,BT_HDR * p_buf)600 void l2c_fcr_proc_pdu(tL2C_CCB* p_ccb, BT_HDR* p_buf) {
601   CHECK(p_ccb != NULL);
602   CHECK(p_buf != NULL);
603   uint8_t* p;
604   uint16_t fcs;
605   uint16_t min_pdu_len;
606   uint16_t ctrl_word;
607 
608   /* Check the length */
609   min_pdu_len = (p_ccb->bypass_fcs == L2CAP_BYPASS_FCS)
610                     ? (uint16_t)L2CAP_FCR_OVERHEAD
611                     : (uint16_t)(L2CAP_FCS_LEN + L2CAP_FCR_OVERHEAD);
612 
613   if (p_buf->len < min_pdu_len) {
614     L2CAP_TRACE_WARNING("Rx L2CAP PDU: CID: 0x%04x  Len too short: %u",
615                         p_ccb->local_cid, p_buf->len);
616     osi_free(p_buf);
617     return;
618   }
619 
620   if (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_STREAM_MODE) {
621     process_stream_frame(p_ccb, p_buf);
622     return;
623   }
624 
625   /* Get the control word */
626   p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
627   STREAM_TO_UINT16(ctrl_word, p);
628 
629   if (ctrl_word & L2CAP_FCR_S_FRAME_BIT) {
630     if ((((ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT) == 1) ||
631         (((ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT) == 3)) {
632       /* REJ or SREJ */
633       L2CAP_TRACE_WARNING(
634           "L2CAP eRTM Rx S-frame: cid: 0x%04x  Len: %u  Type: %s  ReqSeq: %u  "
635           "P: %u  F: %u",
636           p_ccb->local_cid, p_buf->len,
637           SUP_types[(ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT],
638           (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
639           (ctrl_word & L2CAP_FCR_P_BIT) >> L2CAP_FCR_P_BIT_SHIFT,
640           (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
641     } else {
642       L2CAP_TRACE_EVENT(
643           "L2CAP eRTM Rx S-frame: cid: 0x%04x  Len: %u  Type: %s  ReqSeq: %u  "
644           "P: %u  F: %u",
645           p_ccb->local_cid, p_buf->len,
646           SUP_types[(ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT],
647           (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
648           (ctrl_word & L2CAP_FCR_P_BIT) >> L2CAP_FCR_P_BIT_SHIFT,
649           (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
650     }
651   } else {
652     L2CAP_TRACE_EVENT(
653         "L2CAP eRTM Rx I-frame: cid: 0x%04x  Len: %u  SAR: %-12s  TxSeq: %u  "
654         "ReqSeq: %u  F: %u",
655         p_ccb->local_cid, p_buf->len,
656         SAR_types[(ctrl_word & L2CAP_FCR_SAR_BITS) >> L2CAP_FCR_SAR_BITS_SHIFT],
657         (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT,
658         (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
659         (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
660   }
661 
662   L2CAP_TRACE_EVENT(
663       "      eRTM Rx Nxt_tx_seq %u, Lst_rx_ack %u, Nxt_seq_exp %u, Lst_ack_snt "
664       "%u, wt_q.cnt %u, tries %u",
665       p_ccb->fcrb.next_tx_seq, p_ccb->fcrb.last_rx_ack,
666       p_ccb->fcrb.next_seq_expected, p_ccb->fcrb.last_ack_sent,
667       fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q), p_ccb->fcrb.num_tries);
668 
669   /* Verify FCS if using */
670   if (p_ccb->bypass_fcs != L2CAP_BYPASS_FCS) {
671     p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + p_buf->len - L2CAP_FCS_LEN;
672 
673     /* Extract and drop the FCS from the packet */
674     STREAM_TO_UINT16(fcs, p);
675     p_buf->len -= L2CAP_FCS_LEN;
676 
677     if (l2c_fcr_rx_get_fcs(p_buf) != fcs) {
678       L2CAP_TRACE_WARNING("Rx L2CAP PDU: CID: 0x%04x  BAD FCS",
679                           p_ccb->local_cid);
680       osi_free(p_buf);
681       return;
682     }
683   }
684 
685   /* Get the control word */
686   p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
687 
688   STREAM_TO_UINT16(ctrl_word, p);
689 
690   p_buf->len -= L2CAP_FCR_OVERHEAD;
691   p_buf->offset += L2CAP_FCR_OVERHEAD;
692 
693   /* If we had a poll bit outstanding, check if we got a final response */
694   if (p_ccb->fcrb.wait_ack) {
695     /* If final bit not set, ignore the frame unless it is a polled S-frame */
696     if (!(ctrl_word & L2CAP_FCR_F_BIT)) {
697       if ((ctrl_word & L2CAP_FCR_P_BIT) &&
698           (ctrl_word & L2CAP_FCR_S_FRAME_BIT)) {
699         if (p_ccb->fcrb.srej_sent)
700           l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_SREJ, L2CAP_FCR_F_BIT);
701         else
702           l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, L2CAP_FCR_F_BIT);
703 
704         /* Got a poll while in wait_ack state, so re-start our timer with
705          * 1-second */
706         /* This is a small optimization... the monitor timer is 12 secs, but we
707          * saw */
708         /* that if the other side sends us a poll when we are waiting for a
709          * final,  */
710         /* then it speeds up recovery significantly if we poll it back soon
711          * after its poll. */
712         alarm_set_on_mloop(p_ccb->fcrb.mon_retrans_timer, BT_1SEC_TIMEOUT_MS,
713                            l2c_ccb_timer_timeout, p_ccb);
714       }
715       osi_free(p_buf);
716       return;
717     }
718 
719     p_ccb->fcrb.wait_ack = false;
720 
721     /* P and F are mutually exclusive */
722     if (ctrl_word & L2CAP_FCR_S_FRAME_BIT) ctrl_word &= ~L2CAP_FCR_P_BIT;
723 
724     if (fixed_queue_is_empty(p_ccb->fcrb.waiting_for_ack_q))
725       p_ccb->fcrb.num_tries = 0;
726 
727     l2c_fcr_stop_timer(p_ccb);
728   } else {
729     /* Otherwise, ensure the final bit is ignored */
730     ctrl_word &= ~L2CAP_FCR_F_BIT;
731   }
732 
733   /* Process receive sequence number */
734   if (!process_reqseq(p_ccb, ctrl_word)) {
735     osi_free(p_buf);
736     return;
737   }
738 
739   /* Process based on whether it is an S-frame or an I-frame */
740   if (ctrl_word & L2CAP_FCR_S_FRAME_BIT)
741     process_s_frame(p_ccb, p_buf, ctrl_word);
742   else
743     process_i_frame(p_ccb, p_buf, ctrl_word, false);
744 
745   /* Return if the channel got disconnected by a bad packet or max
746    * retransmissions */
747   if ((!p_ccb->in_use) || (p_ccb->chnl_state != CST_OPEN)) return;
748 
749   /* If we have some buffers held while doing SREJ, and SREJ has cleared,
750    * process them now */
751   if ((!p_ccb->fcrb.srej_sent) &&
752       (!fixed_queue_is_empty(p_ccb->fcrb.srej_rcv_hold_q))) {
753     fixed_queue_t* temp_q = p_ccb->fcrb.srej_rcv_hold_q;
754     p_ccb->fcrb.srej_rcv_hold_q = fixed_queue_new(SIZE_MAX);
755 
756     while ((p_buf = (BT_HDR*)fixed_queue_try_dequeue(temp_q)) != NULL) {
757       if (p_ccb->in_use && (p_ccb->chnl_state == CST_OPEN)) {
758         /* Get the control word */
759         p = ((uint8_t*)(p_buf + 1)) + p_buf->offset - L2CAP_FCR_OVERHEAD;
760 
761         STREAM_TO_UINT16(ctrl_word, p);
762 
763         L2CAP_TRACE_DEBUG(
764             "l2c_fcr_proc_pdu() CID: 0x%04x  Process Buffer from SREJ_Hold_Q   "
765             "TxSeq: %u  Expected_Seq: %u",
766             p_ccb->local_cid,
767             (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT,
768             p_ccb->fcrb.next_seq_expected);
769 
770         /* Process the SREJ held I-frame, but do not send an RR for each
771          * individual frame */
772         process_i_frame(p_ccb, p_buf, ctrl_word, true);
773       } else
774         osi_free(p_buf);
775 
776       /* If more frames were lost during SREJ, send a REJ */
777       if (p_ccb->fcrb.rej_after_srej) {
778         p_ccb->fcrb.rej_after_srej = false;
779         p_ccb->fcrb.rej_sent = true;
780 
781         l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_REJ, 0);
782       }
783     }
784     fixed_queue_free(temp_q, NULL);
785 
786     /* Now, if needed, send one RR for the whole held queue */
787     if ((!p_ccb->fcrb.rej_sent) && (!p_ccb->fcrb.srej_sent) &&
788         (p_ccb->fcrb.next_seq_expected != p_ccb->fcrb.last_ack_sent))
789       l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, 0);
790     else {
791       L2CAP_TRACE_DEBUG(
792           "l2c_fcr_proc_pdu() not sending RR CID: 0x%04x  local_busy:%d "
793           "rej_sent:%d srej_sent:%d Expected_Seq:%u Last_Ack:%u",
794           p_ccb->local_cid, 0, p_ccb->fcrb.rej_sent, p_ccb->fcrb.srej_sent,
795           p_ccb->fcrb.next_seq_expected, p_ccb->fcrb.last_ack_sent);
796     }
797   }
798 
799   /* If a window has opened, check if we can send any more packets */
800   if ((!fixed_queue_is_empty(p_ccb->fcrb.retrans_q) ||
801        !fixed_queue_is_empty(p_ccb->xmit_hold_q)) &&
802       (!p_ccb->fcrb.wait_ack) && (!l2c_fcr_is_flow_controlled(p_ccb))) {
803     l2c_link_check_send_pkts(p_ccb->p_lcb, NULL, NULL);
804   }
805 }
806 
807 /*******************************************************************************
808  *
809  * Function         l2c_lcc_proc_pdu
810  *
811  * Description      This function is the entry point for processing of a
812  *                  received PDU when in LE Coc flow control modes.
813  *
814  * Returns          -
815  *
816  ******************************************************************************/
l2c_lcc_proc_pdu(tL2C_CCB * p_ccb,BT_HDR * p_buf)817 void l2c_lcc_proc_pdu(tL2C_CCB* p_ccb, BT_HDR* p_buf) {
818   CHECK(p_ccb != NULL);
819   CHECK(p_buf != NULL);
820   uint8_t* p = (uint8_t*)(p_buf + 1) + p_buf->offset;
821   uint16_t sdu_length;
822   BT_HDR* p_data = NULL;
823 
824   /* Buffer length should not exceed local mps */
825   if (p_buf->len > p_ccb->local_conn_cfg.mps) {
826     /* Discard the buffer */
827     osi_free(p_buf);
828     return;
829   }
830 
831   if (p_ccb->is_first_seg) {
832     if (p_buf->len < sizeof(sdu_length)) {
833       L2CAP_TRACE_ERROR("%s: buffer length=%d too small. Need at least 2.",
834                         __func__, p_buf->len);
835       android_errorWriteWithInfoLog(0x534e4554, "120665616", -1, NULL, 0);
836       /* Discard the buffer */
837       osi_free(p_buf);
838       return;
839     }
840     STREAM_TO_UINT16(sdu_length, p);
841 
842     /* Check the SDU Length with local MTU size */
843     if (sdu_length > p_ccb->local_conn_cfg.mtu) {
844       /* Discard the buffer */
845       osi_free(p_buf);
846       return;
847     }
848 
849     p_buf->len -= sizeof(sdu_length);
850     p_buf->offset += sizeof(sdu_length);
851 
852     if (sdu_length < p_buf->len) {
853       L2CAP_TRACE_ERROR("%s: Invalid sdu_length: %d", __func__, sdu_length);
854       android_errorWriteWithInfoLog(0x534e4554, "112321180", -1, NULL, 0);
855       /* Discard the buffer */
856       osi_free(p_buf);
857       return;
858     }
859 
860     p_data = (BT_HDR*)osi_malloc(BT_HDR_SIZE + sdu_length);
861     if (p_data == NULL) {
862       osi_free(p_buf);
863       return;
864     }
865 
866     p_ccb->ble_sdu = p_data;
867     p_data->len = 0;
868     p_ccb->ble_sdu_length = sdu_length;
869     L2CAP_TRACE_DEBUG("%s SDU Length = %d", __func__, sdu_length);
870     p_data->offset = 0;
871 
872   } else {
873     p_data = p_ccb->ble_sdu;
874     if (p_buf->len > (p_ccb->ble_sdu_length - p_data->len)) {
875       L2CAP_TRACE_ERROR("%s: buffer length=%d too big. max=%d. Dropped",
876                         __func__, p_data->len,
877                         (p_ccb->ble_sdu_length - p_data->len));
878       android_errorWriteWithInfoLog(0x534e4554, "75298652", -1, NULL, 0);
879       osi_free(p_buf);
880 
881       /* Throw away all pending fragments and disconnects */
882       p_ccb->is_first_seg = true;
883       osi_free(p_ccb->ble_sdu);
884       p_ccb->ble_sdu = NULL;
885       p_ccb->ble_sdu_length = 0;
886       l2cu_disconnect_chnl(p_ccb);
887       return;
888     }
889   }
890 
891   memcpy((uint8_t*)(p_data + 1) + p_data->offset + p_data->len,
892          (uint8_t*)(p_buf + 1) + p_buf->offset, p_buf->len);
893   p_data->len += p_buf->len;
894   p = (uint8_t*)(p_data + 1) + p_data->offset;
895   if (p_data->len == p_ccb->ble_sdu_length) {
896     l2c_csm_execute(p_ccb, L2CEVT_L2CAP_DATA, p_data);
897     p_ccb->is_first_seg = true;
898     p_ccb->ble_sdu = NULL;
899     p_ccb->ble_sdu_length = 0;
900   } else if (p_data->len < p_ccb->ble_sdu_length) {
901     p_ccb->is_first_seg = false;
902   }
903 
904   osi_free(p_buf);
905   return;
906 }
907 
908 /*******************************************************************************
909  *
910  * Function         l2c_fcr_proc_tout
911  *
912  * Description      Handle a timeout. We should be in error recovery state.
913  *
914  * Returns          -
915  *
916  ******************************************************************************/
l2c_fcr_proc_tout(tL2C_CCB * p_ccb)917 void l2c_fcr_proc_tout(tL2C_CCB* p_ccb) {
918   CHECK(p_ccb != NULL);
919   L2CAP_TRACE_DEBUG(
920       "l2c_fcr_proc_tout:  CID: 0x%04x  num_tries: %u (max: %u)  wait_ack: %u  "
921       "ack_q_count: %u",
922       p_ccb->local_cid, p_ccb->fcrb.num_tries, p_ccb->peer_cfg.fcr.max_transmit,
923       p_ccb->fcrb.wait_ack, fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q));
924 
925 #if (L2CAP_ERTM_STATS == TRUE)
926   p_ccb->fcrb.retrans_touts++;
927 #endif
928 
929   if ((p_ccb->peer_cfg.fcr.max_transmit != 0) &&
930       (++p_ccb->fcrb.num_tries > p_ccb->peer_cfg.fcr.max_transmit)) {
931     l2cu_disconnect_chnl(p_ccb);
932   } else {
933     if (!p_ccb->fcrb.srej_sent && !p_ccb->fcrb.rej_sent) {
934       l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, L2CAP_FCR_P_BIT);
935     }
936   }
937 }
938 
939 /*******************************************************************************
940  *
941  * Function         l2c_fcr_proc_ack_tout
942  *
943  * Description      Send RR/RNR if we have not acked I frame
944  *
945  * Returns          -
946  *
947  ******************************************************************************/
l2c_fcr_proc_ack_tout(tL2C_CCB * p_ccb)948 void l2c_fcr_proc_ack_tout(tL2C_CCB* p_ccb) {
949   CHECK(p_ccb != NULL);
950   L2CAP_TRACE_DEBUG(
951       "l2c_fcr_proc_ack_tout:  CID: 0x%04x State: %u  Wack:%u  Rq:%d  Acked:%d",
952       p_ccb->local_cid, p_ccb->chnl_state, p_ccb->fcrb.wait_ack,
953       p_ccb->fcrb.next_seq_expected, p_ccb->fcrb.last_ack_sent);
954 
955   if ((p_ccb->chnl_state == CST_OPEN) && (!p_ccb->fcrb.wait_ack) &&
956       (p_ccb->fcrb.last_ack_sent != p_ccb->fcrb.next_seq_expected)) {
957 #if (L2CAP_ERTM_STATS == TRUE)
958     p_ccb->fcrb.xmit_ack_touts++;
959 #endif
960     l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, 0);
961   }
962 }
963 
964 /*******************************************************************************
965  *
966  * Function         process_reqseq
967  *
968  * Description      Handle receive sequence number
969  *
970  * Returns          -
971  *
972  ******************************************************************************/
process_reqseq(tL2C_CCB * p_ccb,uint16_t ctrl_word)973 static bool process_reqseq(tL2C_CCB* p_ccb, uint16_t ctrl_word) {
974   CHECK(p_ccb != NULL);
975   tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
976   uint8_t req_seq, num_bufs_acked, xx;
977   uint16_t ls;
978   uint16_t full_sdus_xmitted;
979 
980   /* Receive sequence number does not ack anything for SREJ with P-bit set to
981    * zero */
982   if ((ctrl_word & L2CAP_FCR_S_FRAME_BIT) &&
983       ((ctrl_word & L2CAP_FCR_SUP_BITS) ==
984        (L2CAP_FCR_SUP_SREJ << L2CAP_FCR_SUP_SHIFT)) &&
985       ((ctrl_word & L2CAP_FCR_P_BIT) == 0)) {
986     /* If anything still waiting for ack, restart the timer if it was stopped */
987     if (!fixed_queue_is_empty(p_fcrb->waiting_for_ack_q))
988       l2c_fcr_start_timer(p_ccb);
989 
990     return (true);
991   }
992 
993   /* Extract the receive sequence number from the control word */
994   req_seq =
995       (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT;
996 
997   num_bufs_acked = (req_seq - p_fcrb->last_rx_ack) & L2CAP_FCR_SEQ_MODULO;
998 
999   /* Verify the request sequence is in range before proceeding */
1000   if (num_bufs_acked > fixed_queue_length(p_fcrb->waiting_for_ack_q)) {
1001     /* The channel is closed if ReqSeq is not in range */
1002     L2CAP_TRACE_WARNING(
1003         "L2CAP eRTM Frame BAD Req_Seq - ctrl_word: 0x%04x  req_seq 0x%02x  "
1004         "last_rx_ack: 0x%02x  QCount: %u",
1005         ctrl_word, req_seq, p_fcrb->last_rx_ack,
1006         fixed_queue_length(p_fcrb->waiting_for_ack_q));
1007 
1008     l2cu_disconnect_chnl(p_ccb);
1009     return (false);
1010   }
1011 
1012   p_fcrb->last_rx_ack = req_seq;
1013 
1014   /* Now we can release all acknowledged frames, and restart the retransmission
1015    * timer if needed */
1016   if (num_bufs_acked != 0) {
1017     p_fcrb->num_tries = 0;
1018     full_sdus_xmitted = 0;
1019 
1020 #if (L2CAP_ERTM_STATS == TRUE)
1021     l2c_fcr_collect_ack_delay(p_ccb, num_bufs_acked);
1022 #endif
1023 
1024     for (xx = 0; xx < num_bufs_acked; xx++) {
1025       BT_HDR* p_tmp =
1026           (BT_HDR*)fixed_queue_try_dequeue(p_fcrb->waiting_for_ack_q);
1027       ls = p_tmp->layer_specific & L2CAP_FCR_SAR_BITS;
1028 
1029       if ((ls == L2CAP_FCR_UNSEG_SDU) || (ls == L2CAP_FCR_END_SDU))
1030         full_sdus_xmitted++;
1031 
1032       osi_free(p_tmp);
1033     }
1034 
1035     /* If we are still in a wait_ack state, do not mess with the timer */
1036     if (!p_ccb->fcrb.wait_ack) l2c_fcr_stop_timer(p_ccb);
1037 
1038     /* Check if we need to call the "packet_sent" callback */
1039     if ((p_ccb->p_rcb) && (p_ccb->p_rcb->api.pL2CA_TxComplete_Cb) &&
1040         (full_sdus_xmitted)) {
1041       /* Special case for eRTM, if all packets sent, send 0xFFFF */
1042       if (fixed_queue_is_empty(p_fcrb->waiting_for_ack_q) &&
1043           fixed_queue_is_empty(p_ccb->xmit_hold_q)) {
1044         full_sdus_xmitted = 0xFFFF;
1045       }
1046 
1047       (*p_ccb->p_rcb->api.pL2CA_TxComplete_Cb)(p_ccb->local_cid,
1048                                                full_sdus_xmitted);
1049     }
1050   }
1051 
1052   /* If anything still waiting for ack, restart the timer if it was stopped */
1053   if (!fixed_queue_is_empty(p_fcrb->waiting_for_ack_q))
1054     l2c_fcr_start_timer(p_ccb);
1055   return (true);
1056 }
1057 
1058 /*******************************************************************************
1059  *
1060  * Function         process_s_frame
1061  *
1062  * Description      Process an S frame
1063  *
1064  * Returns          -
1065  *
1066  ******************************************************************************/
process_s_frame(tL2C_CCB * p_ccb,BT_HDR * p_buf,uint16_t ctrl_word)1067 static void process_s_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf,
1068                             uint16_t ctrl_word) {
1069   CHECK(p_ccb != NULL);
1070   CHECK(p_buf != NULL);
1071 
1072   tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
1073   uint16_t s_frame_type =
1074       (ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT;
1075   bool remote_was_busy;
1076   bool all_ok = true;
1077 
1078   if (p_buf->len != 0) {
1079     L2CAP_TRACE_WARNING("Incorrect S-frame Length (%d)", p_buf->len);
1080   }
1081 
1082   L2CAP_TRACE_DEBUG("process_s_frame ctrl_word 0x%04x fcrb_remote_busy:%d",
1083                     ctrl_word, p_fcrb->remote_busy);
1084 
1085 #if (L2CAP_ERTM_STATS == TRUE)
1086   p_ccb->fcrb.s_frames_rcvd[s_frame_type]++;
1087 #endif
1088 
1089   if (ctrl_word & L2CAP_FCR_P_BIT) {
1090     p_fcrb->rej_sent = false;  /* After checkpoint, we can send anoher REJ */
1091     p_fcrb->send_f_rsp = true; /* Set a flag in case an I-frame is pending */
1092   }
1093 
1094   switch (s_frame_type) {
1095     case L2CAP_FCR_SUP_RR:
1096       remote_was_busy = p_fcrb->remote_busy;
1097       p_fcrb->remote_busy = false;
1098 
1099       if ((ctrl_word & L2CAP_FCR_F_BIT) || (remote_was_busy))
1100         all_ok = retransmit_i_frames(p_ccb, L2C_FCR_RETX_ALL_PKTS);
1101       break;
1102 
1103     case L2CAP_FCR_SUP_REJ:
1104       p_fcrb->remote_busy = false;
1105       all_ok = retransmit_i_frames(p_ccb, L2C_FCR_RETX_ALL_PKTS);
1106       break;
1107 
1108     case L2CAP_FCR_SUP_RNR:
1109       p_fcrb->remote_busy = true;
1110       l2c_fcr_stop_timer(p_ccb);
1111       break;
1112 
1113     case L2CAP_FCR_SUP_SREJ:
1114       p_fcrb->remote_busy = false;
1115       all_ok = retransmit_i_frames(
1116           p_ccb, (uint8_t)((ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >>
1117                            L2CAP_FCR_REQ_SEQ_BITS_SHIFT));
1118       break;
1119   }
1120 
1121   if (all_ok) {
1122     /* If polled, we need to respond with F-bit. Note, we may have sent a
1123      * I-frame with the F-bit */
1124     if (p_fcrb->send_f_rsp) {
1125       if (p_fcrb->srej_sent)
1126         l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_SREJ, L2CAP_FCR_F_BIT);
1127       else
1128         l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, L2CAP_FCR_F_BIT);
1129 
1130       p_fcrb->send_f_rsp = false;
1131     }
1132   } else {
1133     L2CAP_TRACE_DEBUG("process_s_frame hit_max_retries");
1134   }
1135 
1136   osi_free(p_buf);
1137 }
1138 
1139 /*******************************************************************************
1140  *
1141  * Function         process_i_frame
1142  *
1143  * Description      Process an I frame
1144  *
1145  * Returns          -
1146  *
1147  ******************************************************************************/
process_i_frame(tL2C_CCB * p_ccb,BT_HDR * p_buf,uint16_t ctrl_word,bool delay_ack)1148 static void process_i_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf, uint16_t ctrl_word,
1149                             bool delay_ack) {
1150   CHECK(p_ccb != NULL);
1151   CHECK(p_buf != NULL);
1152 
1153   tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
1154   uint8_t tx_seq, num_lost, num_to_ack, next_srej;
1155 
1156   /* If we were doing checkpoint recovery, first retransmit all unacked I-frames
1157    */
1158   if (ctrl_word & L2CAP_FCR_F_BIT) {
1159     if (!retransmit_i_frames(p_ccb, L2C_FCR_RETX_ALL_PKTS)) {
1160       osi_free(p_buf);
1161       return;
1162     }
1163   }
1164 
1165 #if (L2CAP_ERTM_STATS == TRUE)
1166   p_ccb->fcrb.ertm_pkt_counts[1]++;
1167   p_ccb->fcrb.ertm_byte_counts[1] += p_buf->len;
1168 #endif
1169 
1170   /* Extract the sequence number */
1171   tx_seq = (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT;
1172 
1173   /* Check if tx-sequence is the expected one */
1174   if (tx_seq != p_fcrb->next_seq_expected) {
1175     num_lost = (tx_seq - p_fcrb->next_seq_expected) & L2CAP_FCR_SEQ_MODULO;
1176 
1177     /* Is the frame a duplicate ? If so, just drop it */
1178     if (num_lost >= p_ccb->our_cfg.fcr.tx_win_sz) {
1179       /* Duplicate - simply drop it */
1180       L2CAP_TRACE_WARNING(
1181           "process_i_frame() Dropping Duplicate Frame tx_seq:%u  ExpectedTxSeq "
1182           "%u",
1183           tx_seq, p_fcrb->next_seq_expected);
1184       osi_free(p_buf);
1185     } else {
1186       L2CAP_TRACE_WARNING(
1187           "process_i_frame() CID: 0x%04x  Lost: %u  tx_seq:%u  ExpTxSeq %u  "
1188           "Rej: %u  SRej: %u",
1189           p_ccb->local_cid, num_lost, tx_seq, p_fcrb->next_seq_expected,
1190           p_fcrb->rej_sent, p_fcrb->srej_sent);
1191 
1192       if (p_fcrb->srej_sent) {
1193         /* If SREJ sent, save the frame for later processing as long as it is in
1194          * sequence */
1195         next_srej =
1196             (((BT_HDR*)fixed_queue_try_peek_last(p_fcrb->srej_rcv_hold_q))
1197                  ->layer_specific +
1198              1) &
1199             L2CAP_FCR_SEQ_MODULO;
1200 
1201         if ((tx_seq == next_srej) &&
1202             (fixed_queue_length(p_fcrb->srej_rcv_hold_q) <
1203              p_ccb->our_cfg.fcr.tx_win_sz)) {
1204           /* If user gave us a pool for held rx buffers, use that */
1205           /* TODO: Could that happen? Get rid of this code. */
1206           if (p_ccb->ertm_info.fcr_rx_buf_size != L2CAP_FCR_RX_BUF_SIZE) {
1207             BT_HDR* p_buf2;
1208 
1209             /* Adjust offset and len so that control word is copied */
1210             p_buf->offset -= L2CAP_FCR_OVERHEAD;
1211             p_buf->len += L2CAP_FCR_OVERHEAD;
1212 
1213             p_buf2 = l2c_fcr_clone_buf(p_buf, p_buf->offset, p_buf->len);
1214 
1215             if (p_buf2) {
1216               osi_free(p_buf);
1217               p_buf = p_buf2;
1218             }
1219             p_buf->offset += L2CAP_FCR_OVERHEAD;
1220             p_buf->len -= L2CAP_FCR_OVERHEAD;
1221           }
1222           L2CAP_TRACE_DEBUG(
1223               "process_i_frame() Lost: %u  tx_seq:%u  ExpTxSeq %u  Rej: %u  "
1224               "SRej1",
1225               num_lost, tx_seq, p_fcrb->next_seq_expected, p_fcrb->rej_sent);
1226 
1227           p_buf->layer_specific = tx_seq;
1228           fixed_queue_enqueue(p_fcrb->srej_rcv_hold_q, p_buf);
1229         } else {
1230           L2CAP_TRACE_WARNING(
1231               "process_i_frame() CID: 0x%04x  frame dropped in Srej Sent "
1232               "next_srej:%u  hold_q.count:%u  win_sz:%u",
1233               p_ccb->local_cid, next_srej,
1234               fixed_queue_length(p_fcrb->srej_rcv_hold_q),
1235               p_ccb->our_cfg.fcr.tx_win_sz);
1236 
1237           p_fcrb->rej_after_srej = true;
1238           osi_free(p_buf);
1239         }
1240       } else if (p_fcrb->rej_sent) {
1241         L2CAP_TRACE_WARNING(
1242             "process_i_frame() CID: 0x%04x  Lost: %u  tx_seq:%u  ExpTxSeq %u  "
1243             "Rej: 1  SRej: %u",
1244             p_ccb->local_cid, num_lost, tx_seq, p_fcrb->next_seq_expected,
1245             p_fcrb->srej_sent);
1246 
1247         /* If REJ sent, just drop the frame */
1248         osi_free(p_buf);
1249       } else {
1250         L2CAP_TRACE_DEBUG(
1251             "process_i_frame() CID: 0x%04x  tx_seq:%u  ExpTxSeq %u  Rej: %u",
1252             p_ccb->local_cid, tx_seq, p_fcrb->next_seq_expected,
1253             p_fcrb->rej_sent);
1254 
1255         /* If only one lost, we will send SREJ, otherwise we will send REJ */
1256         if (num_lost > 1) {
1257           osi_free(p_buf);
1258           p_fcrb->rej_sent = true;
1259           l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_REJ, 0);
1260         } else {
1261           if (!fixed_queue_is_empty(p_fcrb->srej_rcv_hold_q)) {
1262             L2CAP_TRACE_ERROR(
1263                 "process_i_frame() CID: 0x%04x  sending SREJ tx_seq:%d "
1264                 "hold_q.count:%u",
1265                 p_ccb->local_cid, tx_seq,
1266                 fixed_queue_length(p_fcrb->srej_rcv_hold_q));
1267           }
1268           p_buf->layer_specific = tx_seq;
1269           fixed_queue_enqueue(p_fcrb->srej_rcv_hold_q, p_buf);
1270           p_fcrb->srej_sent = true;
1271           l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_SREJ, 0);
1272         }
1273         alarm_cancel(p_ccb->fcrb.ack_timer);
1274       }
1275     }
1276     return;
1277   }
1278 
1279   /* Seq number is the next expected. Clear possible reject exception in case it
1280    * occured */
1281   p_fcrb->rej_sent = p_fcrb->srej_sent = false;
1282 
1283   /* Adjust the next_seq, so that if the upper layer sends more data in the
1284      callback
1285      context, the received frame is acked by an I-frame. */
1286   p_fcrb->next_seq_expected = (tx_seq + 1) & L2CAP_FCR_SEQ_MODULO;
1287 
1288   /* If any SAR problem in eRTM mode, spec says disconnect. */
1289   if (!do_sar_reassembly(p_ccb, p_buf, ctrl_word)) {
1290     L2CAP_TRACE_WARNING("process_i_frame() CID: 0x%04x  reassembly failed",
1291                         p_ccb->local_cid);
1292     l2cu_disconnect_chnl(p_ccb);
1293     return;
1294   }
1295 
1296   /* RR optimization - if peer can still send us more, then start an ACK timer
1297    */
1298   num_to_ack = (p_fcrb->next_seq_expected - p_fcrb->last_ack_sent) &
1299                L2CAP_FCR_SEQ_MODULO;
1300 
1301   if (num_to_ack < p_ccb->fcrb.max_held_acks) delay_ack = true;
1302 
1303   /* We should neve never ack frame if we are not in OPEN state */
1304   if ((num_to_ack != 0) && p_ccb->in_use && (p_ccb->chnl_state == CST_OPEN)) {
1305     /* If no frames are awaiting transmission or are held, send an RR or RNR
1306      * S-frame for ack */
1307     if (delay_ack) {
1308       /* If it is the first I frame we did not ack, start ack timer */
1309       if (!alarm_is_scheduled(p_ccb->fcrb.ack_timer)) {
1310         alarm_set_on_mloop(p_ccb->fcrb.ack_timer, L2CAP_FCR_ACK_TIMEOUT_MS,
1311                            l2c_fcrb_ack_timer_timeout, p_ccb);
1312       }
1313     } else if ((fixed_queue_is_empty(p_ccb->xmit_hold_q) ||
1314                 l2c_fcr_is_flow_controlled(p_ccb)) &&
1315                fixed_queue_is_empty(p_ccb->fcrb.srej_rcv_hold_q)) {
1316       l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, 0);
1317     }
1318   }
1319 }
1320 
1321 /*******************************************************************************
1322  *
1323  * Function         process_stream_frame
1324  *
1325  * Description      This function processes frames in streaming mode
1326  *
1327  * Returns          -
1328  *
1329  ******************************************************************************/
process_stream_frame(tL2C_CCB * p_ccb,BT_HDR * p_buf)1330 static void process_stream_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf) {
1331   CHECK(p_ccb != NULL);
1332   CHECK(p_buf != NULL);
1333 
1334   uint16_t ctrl_word;
1335   uint16_t fcs;
1336   uint8_t* p;
1337   uint8_t tx_seq;
1338 
1339   /* Verify FCS if using */
1340   if (p_ccb->bypass_fcs != L2CAP_BYPASS_FCS) {
1341     p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + p_buf->len - L2CAP_FCS_LEN;
1342 
1343     /* Extract and drop the FCS from the packet */
1344     STREAM_TO_UINT16(fcs, p);
1345     p_buf->len -= L2CAP_FCS_LEN;
1346 
1347     if (l2c_fcr_rx_get_fcs(p_buf) != fcs) {
1348       L2CAP_TRACE_WARNING("Rx L2CAP PDU: CID: 0x%04x  BAD FCS",
1349                           p_ccb->local_cid);
1350       osi_free(p_buf);
1351       return;
1352     }
1353   }
1354 
1355   /* Get the control word */
1356   p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
1357 
1358   STREAM_TO_UINT16(ctrl_word, p);
1359 
1360   p_buf->len -= L2CAP_FCR_OVERHEAD;
1361   p_buf->offset += L2CAP_FCR_OVERHEAD;
1362 
1363   /* Make sure it is an I-frame */
1364   if (ctrl_word & L2CAP_FCR_S_FRAME_BIT) {
1365     L2CAP_TRACE_WARNING(
1366         "Rx L2CAP PDU: CID: 0x%04x  BAD S-frame in streaming mode  ctrl_word: "
1367         "0x%04x",
1368         p_ccb->local_cid, ctrl_word);
1369     osi_free(p_buf);
1370     return;
1371   }
1372 
1373   L2CAP_TRACE_EVENT(
1374       "L2CAP eRTM Rx I-frame: cid: 0x%04x  Len: %u  SAR: %-12s  TxSeq: %u  "
1375       "ReqSeq: %u  F: %u",
1376       p_ccb->local_cid, p_buf->len,
1377       SAR_types[(ctrl_word & L2CAP_FCR_SAR_BITS) >> L2CAP_FCR_SAR_BITS_SHIFT],
1378       (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT,
1379       (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
1380       (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
1381 
1382   /* Extract the sequence number */
1383   tx_seq = (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT;
1384 
1385   /* Check if tx-sequence is the expected one */
1386   if (tx_seq != p_ccb->fcrb.next_seq_expected) {
1387     L2CAP_TRACE_WARNING(
1388         "Rx L2CAP PDU: CID: 0x%04x  Lost frames Exp: %u  Got: %u  p_rx_sdu: "
1389         "0x%08x",
1390         p_ccb->local_cid, p_ccb->fcrb.next_seq_expected, tx_seq,
1391         p_ccb->fcrb.p_rx_sdu);
1392 
1393     /* Lost one or more packets, so flush the SAR queue */
1394     osi_free_and_reset((void**)&p_ccb->fcrb.p_rx_sdu);
1395   }
1396 
1397   p_ccb->fcrb.next_seq_expected = (tx_seq + 1) & L2CAP_FCR_SEQ_MODULO;
1398 
1399   if (!do_sar_reassembly(p_ccb, p_buf, ctrl_word)) {
1400     /* Some sort of SAR error, so flush the SAR queue */
1401     osi_free_and_reset((void**)&p_ccb->fcrb.p_rx_sdu);
1402   }
1403 }
1404 
1405 /*******************************************************************************
1406  *
1407  * Function         do_sar_reassembly
1408  *
1409  * Description      Process SAR bits and re-assemble frame
1410  *
1411  * Returns          true if all OK, else false
1412  *
1413  ******************************************************************************/
do_sar_reassembly(tL2C_CCB * p_ccb,BT_HDR * p_buf,uint16_t ctrl_word)1414 static bool do_sar_reassembly(tL2C_CCB* p_ccb, BT_HDR* p_buf,
1415                               uint16_t ctrl_word) {
1416   CHECK(p_ccb != NULL);
1417   CHECK(p_buf != NULL);
1418 
1419   tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
1420   uint16_t sar_type = ctrl_word & L2CAP_FCR_SEG_BITS;
1421   bool packet_ok = true;
1422   uint8_t* p;
1423 
1424   /* Check if the SAR state is correct */
1425   if ((sar_type == L2CAP_FCR_UNSEG_SDU) || (sar_type == L2CAP_FCR_START_SDU)) {
1426     if (p_fcrb->p_rx_sdu != NULL) {
1427       L2CAP_TRACE_WARNING(
1428           "SAR - got unexpected unsegmented or start SDU  Expected len: %u  "
1429           "Got so far: %u",
1430           p_fcrb->rx_sdu_len, p_fcrb->p_rx_sdu->len);
1431 
1432       packet_ok = false;
1433     }
1434     /* Check the length of the packet */
1435     if ((sar_type == L2CAP_FCR_START_SDU) &&
1436         (p_buf->len < L2CAP_SDU_LEN_OVERHEAD)) {
1437       L2CAP_TRACE_WARNING("SAR start packet too short: %u", p_buf->len);
1438       packet_ok = false;
1439     }
1440   } else {
1441     if (p_fcrb->p_rx_sdu == NULL) {
1442       L2CAP_TRACE_WARNING("SAR - got unexpected cont or end SDU");
1443       packet_ok = false;
1444     }
1445   }
1446 
1447   if ((packet_ok) && (sar_type != L2CAP_FCR_UNSEG_SDU)) {
1448     p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
1449 
1450     /* For start SDU packet, extract the SDU length */
1451     if (sar_type == L2CAP_FCR_START_SDU) {
1452       /* Get the SDU length */
1453       STREAM_TO_UINT16(p_fcrb->rx_sdu_len, p);
1454       p_buf->offset += 2;
1455       p_buf->len -= 2;
1456 
1457       if (p_fcrb->rx_sdu_len > p_ccb->max_rx_mtu) {
1458         L2CAP_TRACE_WARNING("SAR - SDU len: %u  larger than MTU: %u",
1459                             p_fcrb->rx_sdu_len, p_fcrb->rx_sdu_len);
1460         packet_ok = false;
1461       } else {
1462         p_fcrb->p_rx_sdu = (BT_HDR*)osi_malloc(
1463             BT_HDR_SIZE + OBX_BUF_MIN_OFFSET + p_fcrb->rx_sdu_len);
1464         p_fcrb->p_rx_sdu->offset = OBX_BUF_MIN_OFFSET;
1465         p_fcrb->p_rx_sdu->len = 0;
1466       }
1467     }
1468 
1469     if (packet_ok) {
1470       if ((p_fcrb->p_rx_sdu->len + p_buf->len) > p_fcrb->rx_sdu_len) {
1471         L2CAP_TRACE_ERROR(
1472             "SAR - SDU len exceeded  Type: %u   Lengths: %u %u %u", sar_type,
1473             p_fcrb->p_rx_sdu->len, p_buf->len, p_fcrb->rx_sdu_len);
1474         packet_ok = false;
1475       } else if ((sar_type == L2CAP_FCR_END_SDU) &&
1476                  ((p_fcrb->p_rx_sdu->len + p_buf->len) != p_fcrb->rx_sdu_len)) {
1477         L2CAP_TRACE_WARNING("SAR - SDU end rcvd but SDU incomplete: %u %u %u",
1478                             p_fcrb->p_rx_sdu->len, p_buf->len,
1479                             p_fcrb->rx_sdu_len);
1480         packet_ok = false;
1481       } else {
1482         memcpy(((uint8_t*)(p_fcrb->p_rx_sdu + 1)) + p_fcrb->p_rx_sdu->offset +
1483                    p_fcrb->p_rx_sdu->len,
1484                p, p_buf->len);
1485 
1486         p_fcrb->p_rx_sdu->len += p_buf->len;
1487 
1488         osi_free(p_buf);
1489         p_buf = NULL;
1490 
1491         if (sar_type == L2CAP_FCR_END_SDU) {
1492           p_buf = p_fcrb->p_rx_sdu;
1493           p_fcrb->p_rx_sdu = NULL;
1494         }
1495       }
1496     }
1497   }
1498 
1499   if (!packet_ok) {
1500     osi_free(p_buf);
1501   } else if (p_buf != NULL) {
1502 #if (L2CAP_NUM_FIXED_CHNLS > 0)
1503     if (p_ccb->local_cid < L2CAP_BASE_APPL_CID &&
1504         (p_ccb->local_cid >= L2CAP_FIRST_FIXED_CHNL &&
1505          p_ccb->local_cid <= L2CAP_LAST_FIXED_CHNL)) {
1506       if (l2cb.fixed_reg[p_ccb->local_cid - L2CAP_FIRST_FIXED_CHNL]
1507               .pL2CA_FixedData_Cb)
1508         (*l2cb.fixed_reg[p_ccb->local_cid - L2CAP_FIRST_FIXED_CHNL]
1509               .pL2CA_FixedData_Cb)(p_ccb->local_cid,
1510                                    p_ccb->p_lcb->remote_bd_addr, p_buf);
1511     } else
1512 #endif
1513       l2c_csm_execute(p_ccb, L2CEVT_L2CAP_DATA, p_buf);
1514   }
1515 
1516   return (packet_ok);
1517 }
1518 
1519 /*******************************************************************************
1520  *
1521  * Function         retransmit_i_frames
1522  *
1523  * Description      This function retransmits i-frames awaiting acks.
1524  *
1525  * Returns          bool    - true if retransmitted
1526  *
1527  ******************************************************************************/
retransmit_i_frames(tL2C_CCB * p_ccb,uint8_t tx_seq)1528 static bool retransmit_i_frames(tL2C_CCB* p_ccb, uint8_t tx_seq) {
1529   CHECK(p_ccb != NULL);
1530 
1531   BT_HDR* p_buf = NULL;
1532   uint8_t* p;
1533   uint8_t buf_seq;
1534   uint16_t ctrl_word;
1535 
1536   if ((!fixed_queue_is_empty(p_ccb->fcrb.waiting_for_ack_q)) &&
1537       (p_ccb->peer_cfg.fcr.max_transmit != 0) &&
1538       (p_ccb->fcrb.num_tries >= p_ccb->peer_cfg.fcr.max_transmit)) {
1539     L2CAP_TRACE_EVENT(
1540         "Max Tries Exceeded:  (last_acq: %d  CID: 0x%04x  num_tries: %u (max: "
1541         "%u) ack_q_count: %u",
1542         p_ccb->fcrb.last_rx_ack, p_ccb->local_cid, p_ccb->fcrb.num_tries,
1543         p_ccb->peer_cfg.fcr.max_transmit,
1544         fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q));
1545 
1546     l2cu_disconnect_chnl(p_ccb);
1547     return (false);
1548   }
1549 
1550   /* tx_seq indicates whether to retransmit a specific sequence or all (if ==
1551    * L2C_FCR_RETX_ALL_PKTS) */
1552   list_t* list_ack = NULL;
1553   const list_node_t* node_ack = NULL;
1554   if (!fixed_queue_is_empty(p_ccb->fcrb.waiting_for_ack_q)) {
1555     list_ack = fixed_queue_get_list(p_ccb->fcrb.waiting_for_ack_q);
1556     node_ack = list_begin(list_ack);
1557   }
1558   if (tx_seq != L2C_FCR_RETX_ALL_PKTS) {
1559     /* If sending only one, the sequence number tells us which one. Look for it.
1560     */
1561     if (list_ack != NULL) {
1562       for (; node_ack != list_end(list_ack); node_ack = list_next(node_ack)) {
1563         p_buf = (BT_HDR*)list_node(node_ack);
1564         /* Get the old control word */
1565         p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + L2CAP_PKT_OVERHEAD;
1566 
1567         STREAM_TO_UINT16(ctrl_word, p);
1568 
1569         buf_seq =
1570             (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT;
1571 
1572         L2CAP_TRACE_DEBUG(
1573             "retransmit_i_frames()   cur seq: %u  looking for: %u", buf_seq,
1574             tx_seq);
1575 
1576         if (tx_seq == buf_seq) break;
1577       }
1578     }
1579 
1580     if (!p_buf) {
1581       L2CAP_TRACE_ERROR("retransmit_i_frames() UNKNOWN seq: %u  q_count: %u",
1582                         tx_seq,
1583                         fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q));
1584       return (true);
1585     }
1586   } else {
1587     // Iterate though list and flush the amount requested from
1588     // the transmit data queue that satisfy the layer and event conditions.
1589     for (list_node_t* node_tmp = list_begin(p_ccb->p_lcb->link_xmit_data_q);
1590          node_tmp != list_end(p_ccb->p_lcb->link_xmit_data_q);) {
1591       BT_HDR* p_tmp = (BT_HDR*)list_node(node_tmp);
1592       node_tmp = list_next(node_tmp);
1593 
1594       /* Do not flush other CIDs or partial segments */
1595       if ((p_tmp->layer_specific == 0) && (p_tmp->event == p_ccb->local_cid)) {
1596         list_remove(p_ccb->p_lcb->link_xmit_data_q, p_tmp);
1597         osi_free(p_tmp);
1598       }
1599     }
1600 
1601     /* Also flush our retransmission queue */
1602     while (!fixed_queue_is_empty(p_ccb->fcrb.retrans_q))
1603       osi_free(fixed_queue_try_dequeue(p_ccb->fcrb.retrans_q));
1604 
1605     if (list_ack != NULL) node_ack = list_begin(list_ack);
1606   }
1607 
1608   if (list_ack != NULL) {
1609     while (node_ack != list_end(list_ack)) {
1610       p_buf = (BT_HDR*)list_node(node_ack);
1611       node_ack = list_next(node_ack);
1612 
1613       BT_HDR* p_buf2 = l2c_fcr_clone_buf(p_buf, p_buf->offset, p_buf->len);
1614       if (p_buf2) {
1615         p_buf2->layer_specific = p_buf->layer_specific;
1616 
1617         fixed_queue_enqueue(p_ccb->fcrb.retrans_q, p_buf2);
1618       }
1619 
1620       if ((tx_seq != L2C_FCR_RETX_ALL_PKTS) || (p_buf2 == NULL)) break;
1621     }
1622   }
1623 
1624   l2c_link_check_send_pkts(p_ccb->p_lcb, NULL, NULL);
1625 
1626   if (fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q)) {
1627     p_ccb->fcrb.num_tries++;
1628     l2c_fcr_start_timer(p_ccb);
1629   }
1630 
1631   return (true);
1632 }
1633 
1634 /*******************************************************************************
1635  *
1636  * Function         l2c_fcr_get_next_xmit_sdu_seg
1637  *
1638  * Description      Get the next SDU segment to transmit.
1639  *
1640  * Returns          pointer to buffer with segment or NULL
1641  *
1642  ******************************************************************************/
l2c_fcr_get_next_xmit_sdu_seg(tL2C_CCB * p_ccb,uint16_t max_packet_length)1643 BT_HDR* l2c_fcr_get_next_xmit_sdu_seg(tL2C_CCB* p_ccb,
1644                                       uint16_t max_packet_length) {
1645   CHECK(p_ccb != NULL);
1646 
1647   bool first_seg = false, /* The segment is the first part of data  */
1648       mid_seg = false,    /* The segment is the middle part of data */
1649       last_seg = false;   /* The segment is the last part of data   */
1650   uint16_t sdu_len = 0;
1651   BT_HDR *p_buf, *p_xmit;
1652   uint8_t* p;
1653   uint16_t max_pdu = p_ccb->tx_mps /* Needed? - L2CAP_MAX_HEADER_FCS*/;
1654 
1655   /* If there is anything in the retransmit queue, that goes first
1656   */
1657   p_buf = (BT_HDR*)fixed_queue_try_dequeue(p_ccb->fcrb.retrans_q);
1658   if (p_buf != NULL) {
1659     /* Update Rx Seq and FCS if we acked some packets while this one was queued
1660      */
1661     prepare_I_frame(p_ccb, p_buf, true);
1662 
1663     p_buf->event = p_ccb->local_cid;
1664 
1665 #if (L2CAP_ERTM_STATS == TRUE)
1666     p_ccb->fcrb.pkts_retransmitted++;
1667     p_ccb->fcrb.ertm_pkt_counts[0]++;
1668     p_ccb->fcrb.ertm_byte_counts[0] += (p_buf->len - 8);
1669 #endif
1670     return (p_buf);
1671   }
1672 
1673   /* For BD/EDR controller, max_packet_length is set to 0             */
1674   /* For AMP controller, max_packet_length is set by available blocks */
1675   if ((max_packet_length > L2CAP_MAX_HEADER_FCS) &&
1676       (max_pdu + L2CAP_MAX_HEADER_FCS > max_packet_length)) {
1677     max_pdu = max_packet_length - L2CAP_MAX_HEADER_FCS;
1678   }
1679 
1680   p_buf = (BT_HDR*)fixed_queue_try_peek_first(p_ccb->xmit_hold_q);
1681 
1682   /* If there is more data than the MPS, it requires segmentation */
1683   if (p_buf->len > max_pdu) {
1684     /* We are using the "event" field to tell is if we already started
1685      * segmentation */
1686     if (p_buf->event == 0) {
1687       first_seg = true;
1688       sdu_len = p_buf->len;
1689     } else
1690       mid_seg = true;
1691 
1692     /* Get a new buffer and copy the data that can be sent in a PDU */
1693     p_xmit = l2c_fcr_clone_buf(p_buf, L2CAP_MIN_OFFSET + L2CAP_SDU_LEN_OFFSET,
1694                                max_pdu);
1695 
1696     if (p_xmit != NULL) {
1697       p_buf->event = p_ccb->local_cid;
1698       p_xmit->event = p_ccb->local_cid;
1699 
1700       p_buf->len -= max_pdu;
1701       p_buf->offset += max_pdu;
1702 
1703       /* copy PBF setting */
1704       p_xmit->layer_specific = p_buf->layer_specific;
1705     } else /* Should never happen if the application has configured buffers
1706               correctly */
1707     {
1708       L2CAP_TRACE_ERROR(
1709           "L2CAP - cannot get buffer for segmentation, max_pdu: %u", max_pdu);
1710       return (NULL);
1711     }
1712   } else /* Use the original buffer if no segmentation, or the last segment */
1713   {
1714     p_xmit = (BT_HDR*)fixed_queue_try_dequeue(p_ccb->xmit_hold_q);
1715 
1716     if (p_xmit->event != 0) last_seg = true;
1717 
1718     p_xmit->event = p_ccb->local_cid;
1719   }
1720 
1721   /* Step back to add the L2CAP headers */
1722   p_xmit->offset -= (L2CAP_PKT_OVERHEAD + L2CAP_FCR_OVERHEAD);
1723   p_xmit->len += L2CAP_PKT_OVERHEAD + L2CAP_FCR_OVERHEAD;
1724 
1725   if (first_seg) {
1726     p_xmit->offset -= L2CAP_SDU_LEN_OVERHEAD;
1727     p_xmit->len += L2CAP_SDU_LEN_OVERHEAD;
1728   }
1729 
1730   /* Set the pointer to the beginning of the data */
1731   p = (uint8_t*)(p_xmit + 1) + p_xmit->offset;
1732 
1733   /* Now the L2CAP header */
1734 
1735   /* Note: if FCS has to be included then the length is recalculated later */
1736   UINT16_TO_STREAM(p, p_xmit->len - L2CAP_PKT_OVERHEAD);
1737 
1738   UINT16_TO_STREAM(p, p_ccb->remote_cid);
1739 
1740   if (first_seg) {
1741     /* Skip control word and add SDU length */
1742     p += 2;
1743     UINT16_TO_STREAM(p, sdu_len);
1744 
1745     /* We will store the SAR type in layer-specific */
1746     /* layer_specific is shared with flushable flag(bits 0-1), don't clear it */
1747     p_xmit->layer_specific |= L2CAP_FCR_START_SDU;
1748 
1749     first_seg = false;
1750   } else if (mid_seg)
1751     p_xmit->layer_specific |= L2CAP_FCR_CONT_SDU;
1752   else if (last_seg)
1753     p_xmit->layer_specific |= L2CAP_FCR_END_SDU;
1754   else
1755     p_xmit->layer_specific |= L2CAP_FCR_UNSEG_SDU;
1756 
1757   prepare_I_frame(p_ccb, p_xmit, false);
1758 
1759   if (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE) {
1760     BT_HDR* p_wack =
1761         l2c_fcr_clone_buf(p_xmit, HCI_DATA_PREAMBLE_SIZE, p_xmit->len);
1762 
1763     if (!p_wack) {
1764       L2CAP_TRACE_ERROR(
1765           "L2CAP - no buffer for xmit cloning, CID: 0x%04x  Length: %u",
1766           p_ccb->local_cid, p_xmit->len);
1767 
1768       /* We will not save the FCS in case we reconfigure and change options */
1769       if (p_ccb->bypass_fcs != L2CAP_BYPASS_FCS) p_xmit->len -= L2CAP_FCS_LEN;
1770 
1771       /* Pretend we sent it and it got lost */
1772       fixed_queue_enqueue(p_ccb->fcrb.waiting_for_ack_q, p_xmit);
1773       return (NULL);
1774     } else {
1775 #if (L2CAP_ERTM_STATS == TRUE)
1776       /* set timestamp at the end of tx I-frame to get acking delay */
1777       /*
1778        * NOTE: Here we assume the allocate buffer is large enough
1779        * to include extra 4 octets at the end.
1780        */
1781       p = ((uint8_t*)(p_wack + 1)) + p_wack->offset + p_wack->len;
1782       // Have to cast to uint32_t which wraps in 49.7 days
1783       UINT32_TO_STREAM(p, static_cast<uint32_t>(
1784                               bluetooth::common::time_get_os_boottime_ms()));
1785 #endif
1786       /* We will not save the FCS in case we reconfigure and change options */
1787       if (p_ccb->bypass_fcs != L2CAP_BYPASS_FCS) p_wack->len -= L2CAP_FCS_LEN;
1788 
1789       p_wack->layer_specific = p_xmit->layer_specific;
1790       fixed_queue_enqueue(p_ccb->fcrb.waiting_for_ack_q, p_wack);
1791     }
1792 
1793 #if (L2CAP_ERTM_STATS == TRUE)
1794     p_ccb->fcrb.ertm_pkt_counts[0]++;
1795     p_ccb->fcrb.ertm_byte_counts[0] += (p_xmit->len - 8);
1796 #endif
1797   }
1798 
1799   return (p_xmit);
1800 }
1801 
1802 /** Get the next PDU to transmit for LE connection oriented channel. Returns
1803  * pointer to buffer with PDU. |last_piece_of_sdu| will be set to true, if
1804  * returned PDU is last piece from this SDU.*/
l2c_lcc_get_next_xmit_sdu_seg(tL2C_CCB * p_ccb,bool * last_piece_of_sdu)1805 BT_HDR* l2c_lcc_get_next_xmit_sdu_seg(tL2C_CCB* p_ccb,
1806                                       bool* last_piece_of_sdu) {
1807   uint16_t max_pdu = p_ccb->peer_conn_cfg.mps - 4 /* Length and CID */;
1808 
1809   BT_HDR* p_buf = (BT_HDR*)fixed_queue_try_peek_first(p_ccb->xmit_hold_q);
1810   bool first_pdu = (p_buf->event == 0) ? true : false;
1811 
1812   uint16_t no_of_bytes_to_send = std::min(
1813       p_buf->len,
1814       (uint16_t)(first_pdu ? (max_pdu - L2CAP_LCC_SDU_LENGTH) : max_pdu));
1815   bool last_pdu = (no_of_bytes_to_send == p_buf->len);
1816 
1817   /* Get a new buffer and copy the data that can be sent in a PDU */
1818   BT_HDR* p_xmit =
1819       l2c_fcr_clone_buf(p_buf, first_pdu ? L2CAP_LCC_OFFSET : L2CAP_MIN_OFFSET,
1820                         no_of_bytes_to_send);
1821 
1822   p_buf->event = p_ccb->local_cid;
1823   p_xmit->event = p_ccb->local_cid;
1824 
1825   if (first_pdu) {
1826     p_xmit->offset -= L2CAP_LCC_SDU_LENGTH; /* for writing the SDU length. */
1827     uint8_t* p = (uint8_t*)(p_xmit + 1) + p_xmit->offset;
1828     UINT16_TO_STREAM(p, p_buf->len);
1829     p_xmit->len += L2CAP_LCC_SDU_LENGTH;
1830   }
1831 
1832   p_buf->len -= no_of_bytes_to_send;
1833   p_buf->offset += no_of_bytes_to_send;
1834 
1835   /* copy PBF setting */
1836   p_xmit->layer_specific = p_buf->layer_specific;
1837 
1838   if (last_piece_of_sdu) *last_piece_of_sdu = last_pdu;
1839 
1840   if (last_pdu) {
1841     p_buf = (BT_HDR*)fixed_queue_try_dequeue(p_ccb->xmit_hold_q);
1842     osi_free(p_buf);
1843   }
1844 
1845   /* Step back to add the L2CAP headers */
1846   p_xmit->offset -= L2CAP_PKT_OVERHEAD;
1847   p_xmit->len += L2CAP_PKT_OVERHEAD;
1848 
1849   /* Set the pointer to the beginning of the data */
1850   uint8_t* p = (uint8_t*)(p_xmit + 1) + p_xmit->offset;
1851 
1852   /* Note: if FCS has to be included then the length is recalculated later */
1853   UINT16_TO_STREAM(p, p_xmit->len - L2CAP_PKT_OVERHEAD);
1854   UINT16_TO_STREAM(p, p_ccb->remote_cid);
1855   return (p_xmit);
1856 }
1857 
1858 /*******************************************************************************
1859  * Configuration negotiation functions
1860  *
1861  * The following functions are used in negotiating channel modes during
1862  * configuration
1863  ******************************************************************************/
1864 
1865 /*******************************************************************************
1866  *
1867  * Function         l2c_fcr_chk_chan_modes
1868  *
1869  * Description      Validates and adjusts if necessary, the FCR options
1870  *                  based on remote EXT features.
1871  *
1872  *                  Note: This assumes peer EXT Features have been received.
1873  *                      Basic mode is used if FCR Options have not been received
1874  *
1875  * Returns          uint8_t - nonzero if can continue, '0' if no compatible
1876  *                            channels
1877  *
1878  ******************************************************************************/
l2c_fcr_chk_chan_modes(tL2C_CCB * p_ccb)1879 uint8_t l2c_fcr_chk_chan_modes(tL2C_CCB* p_ccb) {
1880   CHECK(p_ccb != NULL);
1881 
1882   /* Remove nonbasic options that the peer does not support */
1883   if (!(p_ccb->p_lcb->peer_ext_fea & L2CAP_EXTFEA_ENH_RETRANS))
1884     p_ccb->ertm_info.allowed_modes &= ~L2CAP_FCR_CHAN_OPT_ERTM;
1885 
1886   /* At least one type needs to be set (Basic, ERTM, STM) to continue */
1887   if (!p_ccb->ertm_info.allowed_modes) {
1888     L2CAP_TRACE_WARNING(
1889         "L2CAP - Peer does not support our desired channel types");
1890   }
1891 
1892   return (p_ccb->ertm_info.allowed_modes);
1893 }
1894 
1895 /*******************************************************************************
1896  *
1897  * Function         l2c_fcr_adj_our_req_options
1898  *
1899  * Description      Validates and sets up the FCR options passed in from
1900  *                  L2CA_ConfigReq based on remote device's features.
1901  *
1902  * Returns          true if no errors, Otherwise false
1903  *
1904  ******************************************************************************/
l2c_fcr_adj_our_req_options(tL2C_CCB * p_ccb,tL2CAP_CFG_INFO * p_cfg)1905 bool l2c_fcr_adj_our_req_options(tL2C_CCB* p_ccb, tL2CAP_CFG_INFO* p_cfg) {
1906   CHECK(p_ccb != NULL);
1907   CHECK(p_cfg != NULL);
1908 
1909   tL2CAP_FCR_OPTS* p_fcr = &p_cfg->fcr;
1910 
1911   if (p_fcr->mode != p_ccb->ertm_info.preferred_mode) {
1912     L2CAP_TRACE_WARNING(
1913         "l2c_fcr_adj_our_req_options - preferred_mode (%d), does not match "
1914         "mode (%d)",
1915         p_ccb->ertm_info.preferred_mode, p_fcr->mode);
1916 
1917     /* The preferred mode is passed in through tL2CAP_ERTM_INFO, so override
1918      * this one */
1919     p_fcr->mode = p_ccb->ertm_info.preferred_mode;
1920   }
1921 
1922   /* If upper layer did not request eRTM mode, BASIC must be used */
1923   if (p_ccb->ertm_info.allowed_modes == L2CAP_FCR_CHAN_OPT_BASIC) {
1924     if (p_cfg->fcr_present && p_fcr->mode != L2CAP_FCR_BASIC_MODE) {
1925       L2CAP_TRACE_WARNING(
1926           "l2c_fcr_adj_our_req_options (mode %d): ERROR: No FCR options set "
1927           "using BASIC mode",
1928           p_fcr->mode);
1929     }
1930     p_fcr->mode = L2CAP_FCR_BASIC_MODE;
1931   }
1932 
1933   /* Process the FCR options if initial channel bring-up (not a reconfig
1934   *request)
1935   ** Determine initial channel mode to try based on our options and remote's
1936   *features
1937   */
1938   if (p_cfg->fcr_present && !(p_ccb->config_done & RECONFIG_FLAG)) {
1939     /* We need to have at least one mode type common with the peer */
1940     if (!l2c_fcr_chk_chan_modes(p_ccb)) {
1941       /* Two channels have incompatible supported types */
1942       l2cu_disconnect_chnl(p_ccb);
1943       return (false);
1944     }
1945 
1946     /* Basic is the only common channel mode between the two devices */
1947     else if (p_ccb->ertm_info.allowed_modes == L2CAP_FCR_CHAN_OPT_BASIC) {
1948       /* We only want to try Basic, so bypass sending the FCR options entirely
1949        */
1950       p_cfg->fcr_present = false;
1951       p_cfg->fcs_present = false; /* Illegal to use FCS option in basic mode */
1952       p_cfg->ext_flow_spec_present =
1953           false; /* Illegal to use extended flow spec in basic mode */
1954     }
1955 
1956     /* We have at least one non-basic mode available
1957      * Override mode from available mode options based on preference, if needed
1958      */
1959     else {
1960       /* There is no STREAMING use case, try ERTM */
1961       if (p_fcr->mode == L2CAP_FCR_STREAM_MODE) {
1962         L2CAP_TRACE_DEBUG("L2C CFG: mode is STREAM, but use case; Try ERTM");
1963         p_fcr->mode = L2CAP_FCR_ERTM_MODE;
1964       }
1965 
1966       /* If peer does not support ERTM, try BASIC (will support this if made it
1967        * here in the code) */
1968       if (p_fcr->mode == L2CAP_FCR_ERTM_MODE &&
1969           !(p_ccb->ertm_info.allowed_modes & L2CAP_FCR_CHAN_OPT_ERTM)) {
1970         L2CAP_TRACE_DEBUG(
1971             "L2C CFG: mode is ERTM, but peer does not support; Try BASIC");
1972         p_fcr->mode = L2CAP_FCR_BASIC_MODE;
1973       }
1974     }
1975 
1976     if (p_fcr->mode != L2CAP_FCR_BASIC_MODE) {
1977       /* MTU must be smaller than buffer size */
1978       if ((p_cfg->mtu_present) && (p_cfg->mtu > p_ccb->max_rx_mtu)) {
1979         L2CAP_TRACE_WARNING("L2CAP - MTU: %u  larger than buf size: %u",
1980                             p_cfg->mtu, p_ccb->max_rx_mtu);
1981         return (false);
1982       }
1983 
1984       /* application want to use the default MPS */
1985       if (p_fcr->mps == L2CAP_DEFAULT_ERM_MPS) {
1986         p_fcr->mps = L2CAP_MPS_OVER_BR_EDR;
1987       }
1988       /* MPS must be less than MTU */
1989       else if (p_fcr->mps > p_ccb->max_rx_mtu) {
1990         L2CAP_TRACE_WARNING("L2CAP - MPS  %u  invalid  MTU: %u", p_fcr->mps,
1991                             p_ccb->max_rx_mtu);
1992         return (false);
1993       }
1994 
1995       /* We always initially read into the HCI buffer pool, so make sure it fits
1996        */
1997       if (p_fcr->mps > (L2CAP_MTU_SIZE - L2CAP_MAX_HEADER_FCS))
1998         p_fcr->mps = L2CAP_MTU_SIZE - L2CAP_MAX_HEADER_FCS;
1999     } else {
2000       p_cfg->fcs_present = false; /* Illegal to use FCS option in basic mode */
2001       p_cfg->ext_flow_spec_present =
2002           false; /* Illegal to use extended flow spec in basic mode */
2003     }
2004 
2005     p_ccb->our_cfg.fcr = *p_fcr;
2006   } else /* Not sure how to send a reconfiguration(??) should fcr be included?
2007             */
2008   {
2009     p_ccb->our_cfg.fcr_present = false;
2010   }
2011 
2012   return (true);
2013 }
2014 
2015 /*******************************************************************************
2016  *
2017  * Function         l2c_fcr_adj_monitor_retran_timeout
2018  *
2019  * Description      Overrides monitor/retrans timer value based on controller
2020  *
2021  * Returns          None
2022  *
2023  ******************************************************************************/
l2c_fcr_adj_monitor_retran_timeout(tL2C_CCB * p_ccb)2024 void l2c_fcr_adj_monitor_retran_timeout(tL2C_CCB* p_ccb) {
2025   CHECK(p_ccb != NULL);
2026 
2027   /* adjust our monitor/retran timeout */
2028   if (p_ccb->out_cfg_fcr_present) {
2029     /*
2030     ** if we requestd ERTM or accepted ERTM
2031     ** We may accept ERTM even if we didn't request ERTM, in case of requesting
2032     *STREAM
2033     */
2034     if ((p_ccb->our_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE) ||
2035         (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE)) {
2036       /* upper layer setting is ignored */
2037       p_ccb->our_cfg.fcr.mon_tout = L2CAP_MIN_MONITOR_TOUT;
2038       p_ccb->our_cfg.fcr.rtrans_tout = L2CAP_MIN_RETRANS_TOUT;
2039     } else {
2040       p_ccb->our_cfg.fcr.mon_tout = 0;
2041       p_ccb->our_cfg.fcr.rtrans_tout = 0;
2042     }
2043 
2044     L2CAP_TRACE_DEBUG(
2045         "l2c_fcr_adj_monitor_retran_timeout: mon_tout:%d, rtrans_tout:%d",
2046         p_ccb->our_cfg.fcr.mon_tout, p_ccb->our_cfg.fcr.rtrans_tout);
2047   }
2048 }
2049 /*******************************************************************************
2050  *
2051  * Function         l2c_fcr_adj_our_rsp_options
2052  *
2053  * Description      Overrides any neccesary FCR options passed in from
2054  *                  L2CA_ConfigRsp based on our FCR options.
2055  *                  Only makes adjustments if channel is in ERTM mode.
2056  *
2057  * Returns          None
2058  *
2059  ******************************************************************************/
l2c_fcr_adj_our_rsp_options(tL2C_CCB * p_ccb,tL2CAP_CFG_INFO * p_cfg)2060 void l2c_fcr_adj_our_rsp_options(tL2C_CCB* p_ccb, tL2CAP_CFG_INFO* p_cfg) {
2061   CHECK(p_ccb != NULL);
2062   CHECK(p_cfg != NULL);
2063 
2064   /* adjust our monitor/retran timeout */
2065   l2c_fcr_adj_monitor_retran_timeout(p_ccb);
2066 
2067   p_cfg->fcr_present = p_ccb->out_cfg_fcr_present;
2068 
2069   if (p_cfg->fcr_present) {
2070     /* Temporary - until a better algorithm is implemented */
2071     /* If peer's tx_wnd_sz requires too many buffers for us to support, then
2072      * adjust it. For now, respond with our own tx_wnd_sz. */
2073     /* Note: peer is not guaranteed to obey our adjustment */
2074     if (p_ccb->peer_cfg.fcr.tx_win_sz > p_ccb->our_cfg.fcr.tx_win_sz) {
2075       L2CAP_TRACE_DEBUG("%s: adjusting requested tx_win_sz from %i to %i",
2076                         __func__, p_ccb->peer_cfg.fcr.tx_win_sz,
2077                         p_ccb->our_cfg.fcr.tx_win_sz);
2078       p_ccb->peer_cfg.fcr.tx_win_sz = p_ccb->our_cfg.fcr.tx_win_sz;
2079     }
2080 
2081     p_cfg->fcr.mode = p_ccb->peer_cfg.fcr.mode;
2082     p_cfg->fcr.tx_win_sz = p_ccb->peer_cfg.fcr.tx_win_sz;
2083     p_cfg->fcr.max_transmit = p_ccb->peer_cfg.fcr.max_transmit;
2084     p_cfg->fcr.mps = p_ccb->peer_cfg.fcr.mps;
2085     p_cfg->fcr.rtrans_tout = p_ccb->our_cfg.fcr.rtrans_tout;
2086     p_cfg->fcr.mon_tout = p_ccb->our_cfg.fcr.mon_tout;
2087   }
2088 }
2089 
2090 /*******************************************************************************
2091  *
2092  * Function         l2c_fcr_renegotiate_chan
2093  *
2094  * Description      Called upon unsuccessful peer response to config request.
2095  *                  If the error is because of the channel mode, it will try
2096  *                  to resend using another supported optional channel.
2097  *
2098  * Returns          true if resent configuration, False if channel matches or
2099  *                  cannot match.
2100  *
2101  ******************************************************************************/
l2c_fcr_renegotiate_chan(tL2C_CCB * p_ccb,tL2CAP_CFG_INFO * p_cfg)2102 bool l2c_fcr_renegotiate_chan(tL2C_CCB* p_ccb, tL2CAP_CFG_INFO* p_cfg) {
2103   CHECK(p_ccb != NULL);
2104   CHECK(p_cfg != NULL);
2105 
2106   uint8_t peer_mode = p_ccb->our_cfg.fcr.mode;
2107   bool can_renegotiate;
2108 
2109   /* Skip if this is a reconfiguration from OPEN STATE or if FCR is not returned
2110    */
2111   if (!p_cfg->fcr_present || (p_ccb->config_done & RECONFIG_FLAG))
2112     return (false);
2113 
2114   /* Only retry if there are more channel options to try */
2115   if (p_cfg->result == L2CAP_CFG_UNACCEPTABLE_PARAMS) {
2116     peer_mode = (p_cfg->fcr_present) ? p_cfg->fcr.mode : L2CAP_FCR_BASIC_MODE;
2117 
2118     if (p_ccb->our_cfg.fcr.mode != peer_mode) {
2119       if ((--p_ccb->fcr_cfg_tries) == 0) {
2120         p_cfg->result = L2CAP_CFG_FAILED_NO_REASON;
2121         L2CAP_TRACE_WARNING("l2c_fcr_renegotiate_chan (Max retries exceeded)");
2122       }
2123 
2124       can_renegotiate = false;
2125 
2126       /* Try another supported mode if available based on our last attempted
2127        * channel */
2128       switch (p_ccb->our_cfg.fcr.mode) {
2129         /* Our Streaming mode request was unnacceptable; try ERTM or Basic */
2130         case L2CAP_FCR_STREAM_MODE:
2131           /* Peer wants ERTM and we support it */
2132           if ((peer_mode == L2CAP_FCR_ERTM_MODE) &&
2133               (p_ccb->ertm_info.allowed_modes & L2CAP_FCR_CHAN_OPT_ERTM)) {
2134             L2CAP_TRACE_DEBUG("%s(Trying ERTM)", __func__);
2135             p_ccb->our_cfg.fcr.mode = L2CAP_FCR_ERTM_MODE;
2136             can_renegotiate = true;
2137           } else if (p_ccb->ertm_info.allowed_modes &
2138                      L2CAP_FCR_CHAN_OPT_BASIC) {
2139             /* We can try basic for any other peer mode if we support it */
2140             L2CAP_TRACE_DEBUG("%s(Trying Basic)", __func__);
2141             can_renegotiate = true;
2142             p_ccb->our_cfg.fcr.mode = L2CAP_FCR_BASIC_MODE;
2143           }
2144           break;
2145         case L2CAP_FCR_ERTM_MODE:
2146           /* We can try basic for any other peer mode if we support it */
2147           if (p_ccb->ertm_info.allowed_modes & L2CAP_FCR_CHAN_OPT_BASIC) {
2148             L2CAP_TRACE_DEBUG("%s(Trying Basic)", __func__);
2149             can_renegotiate = true;
2150             p_ccb->our_cfg.fcr.mode = L2CAP_FCR_BASIC_MODE;
2151           }
2152           break;
2153 
2154         default:
2155           /* All other scenarios cannot be renegotiated */
2156           break;
2157       }
2158 
2159       if (can_renegotiate) {
2160         p_ccb->our_cfg.fcr_present = true;
2161 
2162         if (p_ccb->our_cfg.fcr.mode == L2CAP_FCR_BASIC_MODE) {
2163           p_ccb->our_cfg.fcs_present = false;
2164           p_ccb->our_cfg.ext_flow_spec_present = false;
2165 
2166           /* Basic Mode uses ACL Data Pool, make sure the MTU fits */
2167           if ((p_cfg->mtu_present) && (p_cfg->mtu > L2CAP_MTU_SIZE)) {
2168             L2CAP_TRACE_WARNING("L2CAP - adjust MTU: %u too large", p_cfg->mtu);
2169             p_cfg->mtu = L2CAP_MTU_SIZE;
2170           }
2171         }
2172 
2173         l2cu_process_our_cfg_req(p_ccb, &p_ccb->our_cfg);
2174         l2cu_send_peer_config_req(p_ccb, &p_ccb->our_cfg);
2175         alarm_set_on_mloop(p_ccb->l2c_ccb_timer, L2CAP_CHNL_CFG_TIMEOUT_MS,
2176                            l2c_ccb_timer_timeout, p_ccb);
2177         return (true);
2178       }
2179     }
2180   }
2181 
2182   /* Disconnect if the channels do not match */
2183   if (p_ccb->our_cfg.fcr.mode != peer_mode) {
2184     L2CAP_TRACE_WARNING("L2C CFG:  Channels incompatible (local %d, peer %d)",
2185                         p_ccb->our_cfg.fcr.mode, peer_mode);
2186     l2cu_disconnect_chnl(p_ccb);
2187   }
2188 
2189   return (false);
2190 }
2191 
2192 /*******************************************************************************
2193  *
2194  * Function         l2c_fcr_process_peer_cfg_req
2195  *
2196  * Description      This function is called to process the FCR options passed
2197  *                  in the peer's configuration request.
2198  *
2199  * Returns          uint8_t - L2CAP_PEER_CFG_OK, L2CAP_PEER_CFG_UNACCEPTABLE,
2200  *                          or L2CAP_PEER_CFG_DISCONNECT.
2201  *
2202  ******************************************************************************/
l2c_fcr_process_peer_cfg_req(tL2C_CCB * p_ccb,tL2CAP_CFG_INFO * p_cfg)2203 uint8_t l2c_fcr_process_peer_cfg_req(tL2C_CCB* p_ccb, tL2CAP_CFG_INFO* p_cfg) {
2204   CHECK(p_ccb != NULL);
2205   CHECK(p_cfg != NULL);
2206 
2207   uint16_t max_retrans_size;
2208   uint8_t fcr_ok = L2CAP_PEER_CFG_OK;
2209 
2210   p_ccb->p_lcb->w4_info_rsp =
2211       false; /* Handles T61x SonyEricsson Bug in Info Request */
2212 
2213   L2CAP_TRACE_EVENT(
2214       "l2c_fcr_process_peer_cfg_req() CFG fcr_present:%d fcr.mode:%d CCB FCR "
2215       "mode:%d preferred: %u allowed:%u",
2216       p_cfg->fcr_present, p_cfg->fcr.mode, p_ccb->our_cfg.fcr.mode,
2217       p_ccb->ertm_info.preferred_mode, p_ccb->ertm_info.allowed_modes);
2218 
2219   /* If Peer wants basic, we are done (accept it or disconnect) */
2220   if (p_cfg->fcr.mode == L2CAP_FCR_BASIC_MODE) {
2221     /* If we do not allow basic, disconnect */
2222     if (!(p_ccb->ertm_info.allowed_modes & L2CAP_FCR_CHAN_OPT_BASIC))
2223       fcr_ok = L2CAP_PEER_CFG_DISCONNECT;
2224   }
2225 
2226   /* Need to negotiate if our modes are not the same */
2227   else if (p_cfg->fcr.mode != p_ccb->ertm_info.preferred_mode) {
2228     /* If peer wants a mode that we don't support then retry our mode (ex.
2229     *rtx/flc), OR
2230     ** If we want ERTM and they wanted streaming retry our mode.
2231     ** Note: If we have already determined they support our mode previously
2232     **       from their EXF mask.
2233     */
2234     if ((((1 << p_cfg->fcr.mode) & L2CAP_FCR_CHAN_OPT_ALL_MASK) == 0) ||
2235         (p_ccb->ertm_info.preferred_mode == L2CAP_FCR_ERTM_MODE)) {
2236       p_cfg->fcr.mode = p_ccb->our_cfg.fcr.mode;
2237       p_cfg->fcr.tx_win_sz = p_ccb->our_cfg.fcr.tx_win_sz;
2238       p_cfg->fcr.max_transmit = p_ccb->our_cfg.fcr.max_transmit;
2239       fcr_ok = L2CAP_PEER_CFG_UNACCEPTABLE;
2240     }
2241 
2242     /* If we wanted basic, then try to renegotiate it */
2243     else if (p_ccb->ertm_info.preferred_mode == L2CAP_FCR_BASIC_MODE) {
2244       p_cfg->fcr.mode = L2CAP_FCR_BASIC_MODE;
2245       p_cfg->fcr.max_transmit = p_cfg->fcr.tx_win_sz = 0;
2246       p_cfg->fcr.rtrans_tout = p_cfg->fcr.mon_tout = p_cfg->fcr.mps = 0;
2247       p_ccb->our_cfg.fcr.rtrans_tout = p_ccb->our_cfg.fcr.mon_tout =
2248           p_ccb->our_cfg.fcr.mps = 0;
2249       fcr_ok = L2CAP_PEER_CFG_UNACCEPTABLE;
2250     }
2251 
2252     /* Only other valid case is if they want ERTM and we wanted STM which should
2253        be
2254        accepted if we support it; otherwise the channel should be disconnected
2255        */
2256     else if ((p_cfg->fcr.mode != L2CAP_FCR_ERTM_MODE) ||
2257              !(p_ccb->ertm_info.allowed_modes & L2CAP_FCR_CHAN_OPT_ERTM)) {
2258       fcr_ok = L2CAP_PEER_CFG_DISCONNECT;
2259     }
2260   }
2261 
2262   /* Configuration for FCR channels so make any adjustments and fwd to upper
2263    * layer */
2264   if (fcr_ok == L2CAP_PEER_CFG_OK) {
2265     /* by default don't need to send params in the response */
2266     p_ccb->out_cfg_fcr_present = false;
2267 
2268     /* Make any needed adjustments for the response to the peer */
2269     if (p_cfg->fcr_present && p_cfg->fcr.mode != L2CAP_FCR_BASIC_MODE) {
2270       /* Peer desires to bypass FCS check, and streaming or ERTM mode */
2271       if (p_cfg->fcs_present) {
2272         p_ccb->peer_cfg.fcs = p_cfg->fcs;
2273         p_ccb->peer_cfg_bits |= L2CAP_CH_CFG_MASK_FCS;
2274         if (p_cfg->fcs == L2CAP_CFG_FCS_BYPASS)
2275           p_ccb->bypass_fcs |= L2CAP_CFG_FCS_PEER;
2276       }
2277 
2278       max_retrans_size = p_ccb->ertm_info.fcr_tx_buf_size - sizeof(BT_HDR) -
2279                          L2CAP_MIN_OFFSET - L2CAP_SDU_LEN_OFFSET -
2280                          L2CAP_FCS_LEN;
2281 
2282       /* Ensure the MPS is not bigger than the MTU */
2283       if ((p_cfg->fcr.mps == 0) || (p_cfg->fcr.mps > p_ccb->peer_cfg.mtu)) {
2284         p_cfg->fcr.mps = p_ccb->peer_cfg.mtu;
2285         p_ccb->out_cfg_fcr_present = true;
2286       }
2287 
2288       /* Ensure the MPS is not bigger than our retransmission buffer */
2289       if (p_cfg->fcr.mps > max_retrans_size) {
2290         L2CAP_TRACE_DEBUG("CFG: Overriding MPS to %d (orig %d)",
2291                           max_retrans_size, p_cfg->fcr.mps);
2292 
2293         p_cfg->fcr.mps = max_retrans_size;
2294         p_ccb->out_cfg_fcr_present = true;
2295       }
2296 
2297       if (p_cfg->fcr.mode == L2CAP_FCR_ERTM_MODE ||
2298           p_cfg->fcr.mode == L2CAP_FCR_STREAM_MODE) {
2299         /* Always respond with FCR ERTM parameters */
2300         p_ccb->out_cfg_fcr_present = true;
2301       }
2302     }
2303 
2304     /* Everything ok, so save the peer's adjusted fcr options */
2305     p_ccb->peer_cfg.fcr = p_cfg->fcr;
2306 
2307     if (p_cfg->fcr_present) p_ccb->peer_cfg_bits |= L2CAP_CH_CFG_MASK_FCR;
2308   } else if (fcr_ok == L2CAP_PEER_CFG_UNACCEPTABLE) {
2309     /* Allow peer only one retry for mode */
2310     if (p_ccb->peer_cfg_already_rejected)
2311       fcr_ok = L2CAP_PEER_CFG_DISCONNECT;
2312     else
2313       p_ccb->peer_cfg_already_rejected = true;
2314   }
2315 
2316   return (fcr_ok);
2317 }
2318 
2319 #if (L2CAP_ERTM_STATS == TRUE)
2320 /*******************************************************************************
2321  *
2322  * Function         l2c_fcr_collect_ack_delay
2323  *
2324  * Description      collect throughput, delay, queue size of waiting ack
2325  *
2326  * Parameters
2327  *                  tL2C_CCB
2328  *
2329  * Returns          void
2330  *
2331  ******************************************************************************/
l2c_fcr_collect_ack_delay(tL2C_CCB * p_ccb,uint8_t num_bufs_acked)2332 static void l2c_fcr_collect_ack_delay(tL2C_CCB* p_ccb, uint8_t num_bufs_acked) {
2333   uint32_t index;
2334   BT_HDR* p_buf;
2335   uint8_t* p;
2336   uint32_t timestamp, delay;
2337   uint8_t xx;
2338   uint8_t str[120];
2339 
2340   index = p_ccb->fcrb.ack_delay_avg_index;
2341 
2342   /* update sum, max and min of waiting for ack queue size */
2343   p_ccb->fcrb.ack_q_count_avg[index] +=
2344       fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q);
2345 
2346   if (fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q) >
2347       p_ccb->fcrb.ack_q_count_max[index])
2348     p_ccb->fcrb.ack_q_count_max[index] =
2349         fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q);
2350 
2351   if (fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q) <
2352       p_ccb->fcrb.ack_q_count_min[index])
2353     p_ccb->fcrb.ack_q_count_min[index] =
2354         fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q);
2355 
2356   /* update sum, max and min of round trip delay of acking */
2357   list_t* list = NULL;
2358   if (!fixed_queue_is_empty(p_ccb->fcrb.waiting_for_ack_q))
2359     list = fixed_queue_get_list(p_ccb->fcrb.waiting_for_ack_q);
2360   if (list != NULL) {
2361     for (const list_node_t *node = list_begin(list), xx = 0;
2362          (node != list_end(list)) && (xx < num_bufs_acked);
2363          node = list_next(node), xx++) {
2364       p_buf = list_node(node);
2365       /* adding up length of acked I-frames to get throughput */
2366       p_ccb->fcrb.throughput[index] += p_buf->len - 8;
2367 
2368       if (xx == num_bufs_acked - 1) {
2369         /* get timestamp from tx I-frame that receiver is acking */
2370         p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + p_buf->len;
2371         if (p_ccb->bypass_fcs != L2CAP_BYPASS_FCS) {
2372           p += L2CAP_FCS_LEN;
2373         }
2374 
2375         STREAM_TO_UINT32(timestamp, p);
2376         delay = static_cast<uint32_t>(
2377                     bluetooth::common::time_get_os_boottime_ms()) -
2378                 timestamp;
2379 
2380         p_ccb->fcrb.ack_delay_avg[index] += delay;
2381         if (delay > p_ccb->fcrb.ack_delay_max[index])
2382           p_ccb->fcrb.ack_delay_max[index] = delay;
2383         if (delay < p_ccb->fcrb.ack_delay_min[index])
2384           p_ccb->fcrb.ack_delay_min[index] = delay;
2385       }
2386     }
2387   }
2388 
2389   p_ccb->fcrb.ack_delay_avg_count++;
2390 
2391   /* calculate average and initialize next avg, min and max */
2392   if (p_ccb->fcrb.ack_delay_avg_count > L2CAP_ERTM_STATS_AVG_NUM_SAMPLES) {
2393     p_ccb->fcrb.ack_delay_avg_count = 0;
2394 
2395     p_ccb->fcrb.ack_q_count_avg[index] /= L2CAP_ERTM_STATS_AVG_NUM_SAMPLES;
2396     p_ccb->fcrb.ack_delay_avg[index] /= L2CAP_ERTM_STATS_AVG_NUM_SAMPLES;
2397 
2398     /* calculate throughput */
2399     timestamp = bluetooth::common::time_get_os_boottime_ms();
2400     if (timestamp - p_ccb->fcrb.throughput_start > 0)
2401       p_ccb->fcrb.throughput[index] /=
2402           (timestamp - p_ccb->fcrb.throughput_start);
2403 
2404     p_ccb->fcrb.throughput_start = timestamp;
2405 
2406     snprintf(
2407         str, sizeof(str),
2408         "[%02u] throughput: %5u, ack_delay avg:%3u, min:%3u, max:%3u, "
2409         "ack_q_count avg:%3u, min:%3u, max:%3u",
2410         index, p_ccb->fcrb.throughput[index], p_ccb->fcrb.ack_delay_avg[index],
2411         p_ccb->fcrb.ack_delay_min[index], p_ccb->fcrb.ack_delay_max[index],
2412         p_ccb->fcrb.ack_q_count_avg[index], p_ccb->fcrb.ack_q_count_min[index],
2413         p_ccb->fcrb.ack_q_count_max[index]);
2414 
2415     BT_TRACE(TRACE_CTRL_GENERAL | TRACE_LAYER_GKI | TRACE_ORG_GKI,
2416              TRACE_TYPE_GENERIC, "%s", str);
2417 
2418     index = (index + 1) % L2CAP_ERTM_STATS_NUM_AVG;
2419     p_ccb->fcrb.ack_delay_avg_index = index;
2420 
2421     p_ccb->fcrb.ack_q_count_max[index] = 0;
2422     p_ccb->fcrb.ack_q_count_min[index] = 0xFFFFFFFF;
2423     p_ccb->fcrb.ack_q_count_avg[index] = 0;
2424 
2425     p_ccb->fcrb.ack_delay_max[index] = 0;
2426     p_ccb->fcrb.ack_delay_min[index] = 0xFFFFFFFF;
2427     p_ccb->fcrb.ack_delay_avg[index] = 0;
2428 
2429     p_ccb->fcrb.throughput[index] = 0;
2430   }
2431 }
2432 #endif
2433