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 <stdio.h>
28 #include <stdlib.h>
29 #include <string.h>
30
31 #include "common/time_util.h"
32 #include "osi/include/allocator.h"
33 #include "osi/include/log.h"
34 #include "stack/include/bt_hdr.h"
35 #include "stack/include/bt_types.h"
36 #include "stack/include/l2c_api.h"
37 #include "stack/include/l2cdefs.h"
38 #include "stack/l2cap/l2c_int.h"
39
40 /* Flag passed to retransmit_i_frames() when all packets should be retransmitted
41 */
42 #define L2C_FCR_RETX_ALL_PKTS 0xFF
43
44 /* this is the minimal offset required by OBX to process incoming packets */
45 static const uint16_t OBX_BUF_MIN_OFFSET = 4;
46
47 static const char* SAR_types[] = {"Unsegmented", "Start", "End",
48 "Continuation"};
49 static const char* SUP_types[] = {"RR", "REJ", "RNR", "SREJ"};
50
51 /* Look-up table for the CRC calculation */
52 static const unsigned short crctab[256] = {
53 0x0000, 0xc0c1, 0xc181, 0x0140, 0xc301, 0x03c0, 0x0280, 0xc241, 0xc601,
54 0x06c0, 0x0780, 0xc741, 0x0500, 0xc5c1, 0xc481, 0x0440, 0xcc01, 0x0cc0,
55 0x0d80, 0xcd41, 0x0f00, 0xcfc1, 0xce81, 0x0e40, 0x0a00, 0xcac1, 0xcb81,
56 0x0b40, 0xc901, 0x09c0, 0x0880, 0xc841, 0xd801, 0x18c0, 0x1980, 0xd941,
57 0x1b00, 0xdbc1, 0xda81, 0x1a40, 0x1e00, 0xdec1, 0xdf81, 0x1f40, 0xdd01,
58 0x1dc0, 0x1c80, 0xdc41, 0x1400, 0xd4c1, 0xd581, 0x1540, 0xd701, 0x17c0,
59 0x1680, 0xd641, 0xd201, 0x12c0, 0x1380, 0xd341, 0x1100, 0xd1c1, 0xd081,
60 0x1040, 0xf001, 0x30c0, 0x3180, 0xf141, 0x3300, 0xf3c1, 0xf281, 0x3240,
61 0x3600, 0xf6c1, 0xf781, 0x3740, 0xf501, 0x35c0, 0x3480, 0xf441, 0x3c00,
62 0xfcc1, 0xfd81, 0x3d40, 0xff01, 0x3fc0, 0x3e80, 0xfe41, 0xfa01, 0x3ac0,
63 0x3b80, 0xfb41, 0x3900, 0xf9c1, 0xf881, 0x3840, 0x2800, 0xe8c1, 0xe981,
64 0x2940, 0xeb01, 0x2bc0, 0x2a80, 0xea41, 0xee01, 0x2ec0, 0x2f80, 0xef41,
65 0x2d00, 0xedc1, 0xec81, 0x2c40, 0xe401, 0x24c0, 0x2580, 0xe541, 0x2700,
66 0xe7c1, 0xe681, 0x2640, 0x2200, 0xe2c1, 0xe381, 0x2340, 0xe101, 0x21c0,
67 0x2080, 0xe041, 0xa001, 0x60c0, 0x6180, 0xa141, 0x6300, 0xa3c1, 0xa281,
68 0x6240, 0x6600, 0xa6c1, 0xa781, 0x6740, 0xa501, 0x65c0, 0x6480, 0xa441,
69 0x6c00, 0xacc1, 0xad81, 0x6d40, 0xaf01, 0x6fc0, 0x6e80, 0xae41, 0xaa01,
70 0x6ac0, 0x6b80, 0xab41, 0x6900, 0xa9c1, 0xa881, 0x6840, 0x7800, 0xb8c1,
71 0xb981, 0x7940, 0xbb01, 0x7bc0, 0x7a80, 0xba41, 0xbe01, 0x7ec0, 0x7f80,
72 0xbf41, 0x7d00, 0xbdc1, 0xbc81, 0x7c40, 0xb401, 0x74c0, 0x7580, 0xb541,
73 0x7700, 0xb7c1, 0xb681, 0x7640, 0x7200, 0xb2c1, 0xb381, 0x7340, 0xb101,
74 0x71c0, 0x7080, 0xb041, 0x5000, 0x90c1, 0x9181, 0x5140, 0x9301, 0x53c0,
75 0x5280, 0x9241, 0x9601, 0x56c0, 0x5780, 0x9741, 0x5500, 0x95c1, 0x9481,
76 0x5440, 0x9c01, 0x5cc0, 0x5d80, 0x9d41, 0x5f00, 0x9fc1, 0x9e81, 0x5e40,
77 0x5a00, 0x9ac1, 0x9b81, 0x5b40, 0x9901, 0x59c0, 0x5880, 0x9841, 0x8801,
78 0x48c0, 0x4980, 0x8941, 0x4b00, 0x8bc1, 0x8a81, 0x4a40, 0x4e00, 0x8ec1,
79 0x8f81, 0x4f40, 0x8d01, 0x4dc0, 0x4c80, 0x8c41, 0x4400, 0x84c1, 0x8581,
80 0x4540, 0x8701, 0x47c0, 0x4680, 0x8641, 0x8201, 0x42c0, 0x4380, 0x8341,
81 0x4100, 0x81c1, 0x8081, 0x4040,
82 };
83
84 /*******************************************************************************
85 * Static local functions
86 */
87 static bool process_reqseq(tL2C_CCB* p_ccb, uint16_t ctrl_word);
88 static void process_s_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf, uint16_t ctrl_word);
89 static void process_i_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf, uint16_t ctrl_word,
90 bool delay_ack);
91 static bool retransmit_i_frames(tL2C_CCB* p_ccb, uint8_t tx_seq);
92 static void prepare_I_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf,
93 bool is_retransmission);
94 static bool do_sar_reassembly(tL2C_CCB* p_ccb, BT_HDR* p_buf,
95 uint16_t ctrl_word);
96
97 /*******************************************************************************
98 *
99 * Function l2c_fcr_updcrc
100 *
101 * Description This function computes the CRC using the look-up table.
102 *
103 * Returns CRC
104 *
105 ******************************************************************************/
l2c_fcr_updcrc(unsigned short icrc,unsigned char * icp,int icnt)106 static unsigned short l2c_fcr_updcrc(unsigned short icrc, unsigned char* icp,
107 int icnt) {
108 unsigned short crc = icrc;
109 unsigned char* cp = icp;
110 int cnt = icnt;
111
112 while (cnt--) {
113 crc = ((crc >> 8) & 0xff) ^ crctab[(crc & 0xff) ^ *cp++];
114 }
115
116 return (crc);
117 }
118
119 /*******************************************************************************
120 *
121 * Function l2c_fcr_tx_get_fcs
122 *
123 * Description This function computes the CRC for a frame to be TXed.
124 *
125 * Returns CRC
126 *
127 ******************************************************************************/
l2c_fcr_tx_get_fcs(BT_HDR * p_buf)128 static uint16_t l2c_fcr_tx_get_fcs(BT_HDR* p_buf) {
129 uint8_t* p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
130
131 return (l2c_fcr_updcrc(L2CAP_FCR_INIT_CRC, p, p_buf->len));
132 }
133
134 /*******************************************************************************
135 *
136 * Function l2c_fcr_rx_get_fcs
137 *
138 * Description This function computes the CRC for a received frame.
139 *
140 * Returns CRC
141 *
142 ******************************************************************************/
l2c_fcr_rx_get_fcs(BT_HDR * p_buf)143 static uint16_t l2c_fcr_rx_get_fcs(BT_HDR* p_buf) {
144 uint8_t* p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
145
146 /* offset points past the L2CAP header, but the CRC check includes it */
147 p -= L2CAP_PKT_OVERHEAD;
148
149 return (
150 l2c_fcr_updcrc(L2CAP_FCR_INIT_CRC, p, p_buf->len + L2CAP_PKT_OVERHEAD));
151 }
152
153 /*******************************************************************************
154 *
155 * Function l2c_fcr_start_timer
156 *
157 * Description This function starts the (monitor or retransmission) timer.
158 *
159 * Returns -
160 *
161 ******************************************************************************/
l2c_fcr_start_timer(tL2C_CCB * p_ccb)162 void l2c_fcr_start_timer(tL2C_CCB* p_ccb) {
163 CHECK(p_ccb != NULL);
164 uint32_t tout;
165
166 /* The timers which are in milliseconds */
167 if (p_ccb->fcrb.wait_ack) {
168 tout = (uint32_t)p_ccb->our_cfg.fcr.mon_tout;
169 } else {
170 tout = (uint32_t)p_ccb->our_cfg.fcr.rtrans_tout;
171 }
172
173 /* Only start a timer that was not started */
174 if (!alarm_is_scheduled(p_ccb->fcrb.mon_retrans_timer)) {
175 alarm_set_on_mloop(p_ccb->fcrb.mon_retrans_timer, tout,
176 l2c_ccb_timer_timeout, p_ccb);
177 }
178 }
179
180 /*******************************************************************************
181 *
182 * Function l2c_fcr_stop_timer
183 *
184 * Description This function stops the (monitor or transmission) timer.
185 *
186 * Returns -
187 *
188 ******************************************************************************/
l2c_fcr_stop_timer(tL2C_CCB * p_ccb)189 void l2c_fcr_stop_timer(tL2C_CCB* p_ccb) {
190 CHECK(p_ccb != NULL);
191 alarm_cancel(p_ccb->fcrb.mon_retrans_timer);
192 }
193
194 /*******************************************************************************
195 *
196 * Function l2c_fcr_cleanup
197 *
198 * Description This function cleans up the variable used for
199 * flow-control/retrans.
200 *
201 * Returns -
202 *
203 ******************************************************************************/
l2c_fcr_cleanup(tL2C_CCB * p_ccb)204 void l2c_fcr_cleanup(tL2C_CCB* p_ccb) {
205 CHECK(p_ccb != NULL);
206 tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
207
208 alarm_free(p_fcrb->mon_retrans_timer);
209 p_fcrb->mon_retrans_timer = NULL;
210 alarm_free(p_fcrb->ack_timer);
211 p_fcrb->ack_timer = NULL;
212
213 osi_free_and_reset((void**)&p_fcrb->p_rx_sdu);
214
215 fixed_queue_free(p_fcrb->waiting_for_ack_q, osi_free);
216 p_fcrb->waiting_for_ack_q = NULL;
217
218 fixed_queue_free(p_fcrb->srej_rcv_hold_q, osi_free);
219 p_fcrb->srej_rcv_hold_q = NULL;
220
221 fixed_queue_free(p_fcrb->retrans_q, osi_free);
222 p_fcrb->retrans_q = NULL;
223
224 memset(p_fcrb, 0, sizeof(tL2C_FCRB));
225 }
226
227 /*******************************************************************************
228 *
229 * Function l2c_fcr_clone_buf
230 *
231 * Description This function allocates and copies requested part of a
232 * buffer at a new-offset.
233 *
234 * Returns pointer to new buffer
235 *
236 ******************************************************************************/
l2c_fcr_clone_buf(BT_HDR * p_buf,uint16_t new_offset,uint16_t no_of_bytes)237 BT_HDR* l2c_fcr_clone_buf(BT_HDR* p_buf, uint16_t new_offset,
238 uint16_t no_of_bytes) {
239 CHECK(p_buf != NULL);
240 /*
241 * NOTE: We allocate extra L2CAP_FCS_LEN octets, in case we need to put
242 * the FCS (Frame Check Sequence) at the end of the buffer.
243 */
244 uint16_t buf_size = no_of_bytes + sizeof(BT_HDR) + new_offset + L2CAP_FCS_LEN;
245 BT_HDR* p_buf2 = (BT_HDR*)osi_malloc(buf_size);
246
247 p_buf2->offset = new_offset;
248 p_buf2->len = no_of_bytes;
249 memcpy(((uint8_t*)(p_buf2 + 1)) + p_buf2->offset,
250 ((uint8_t*)(p_buf + 1)) + p_buf->offset, no_of_bytes);
251
252 return (p_buf2);
253 }
254
255 /*******************************************************************************
256 *
257 * Function l2c_fcr_is_flow_controlled
258 *
259 * Description This function checks if the CCB is flow controlled by peer.
260 *
261 * Returns The control word
262 *
263 ******************************************************************************/
l2c_fcr_is_flow_controlled(tL2C_CCB * p_ccb)264 bool l2c_fcr_is_flow_controlled(tL2C_CCB* p_ccb) {
265 CHECK(p_ccb != NULL);
266 if (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE) {
267 /* Check if remote side flowed us off or the transmit window is full */
268 if ((p_ccb->fcrb.remote_busy) ||
269 (fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q) >=
270 p_ccb->peer_cfg.fcr.tx_win_sz)) {
271 return (true);
272 }
273 }
274 return (false);
275 }
276
277 /*******************************************************************************
278 *
279 * Function prepare_I_frame
280 *
281 * Description This function sets the FCR variables in an I-frame that is
282 * about to be sent to HCI for transmission. This may be the
283 * first time the I-frame is sent, or a retransmission
284 *
285 * Returns -
286 *
287 ******************************************************************************/
prepare_I_frame(tL2C_CCB * p_ccb,BT_HDR * p_buf,bool is_retransmission)288 static void prepare_I_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf,
289 bool is_retransmission) {
290 CHECK(p_ccb != NULL);
291 CHECK(p_buf != NULL);
292 tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
293 uint8_t* p;
294 uint16_t fcs;
295 uint16_t ctrl_word;
296 bool set_f_bit = p_fcrb->send_f_rsp;
297
298 p_fcrb->send_f_rsp = false;
299
300 if (is_retransmission) {
301 /* Get the old control word and clear out the old req_seq and F bits */
302 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + L2CAP_PKT_OVERHEAD;
303
304 STREAM_TO_UINT16(ctrl_word, p);
305
306 ctrl_word &= ~(L2CAP_FCR_REQ_SEQ_BITS + L2CAP_FCR_F_BIT);
307 } else {
308 ctrl_word = p_buf->layer_specific & L2CAP_FCR_SEG_BITS; /* SAR bits */
309 ctrl_word |=
310 (p_fcrb->next_tx_seq << L2CAP_FCR_TX_SEQ_BITS_SHIFT); /* Tx Seq */
311
312 p_fcrb->next_tx_seq = (p_fcrb->next_tx_seq + 1) & L2CAP_FCR_SEQ_MODULO;
313 }
314
315 /* Set the F-bit and reqseq only if using re-transmission mode */
316 if (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE) {
317 if (set_f_bit) ctrl_word |= L2CAP_FCR_F_BIT;
318
319 ctrl_word |= (p_fcrb->next_seq_expected) << L2CAP_FCR_REQ_SEQ_BITS_SHIFT;
320
321 p_fcrb->last_ack_sent = p_ccb->fcrb.next_seq_expected;
322
323 alarm_cancel(p_ccb->fcrb.ack_timer);
324 }
325
326 /* Set the control word */
327 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + L2CAP_PKT_OVERHEAD;
328
329 UINT16_TO_STREAM(p, ctrl_word);
330
331 /* Compute the FCS and add to the end of the buffer if not bypassed */
332 /* length field in l2cap header has to include FCS length */
333 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
334 UINT16_TO_STREAM(p, p_buf->len + L2CAP_FCS_LEN - L2CAP_PKT_OVERHEAD);
335
336 /* Calculate the FCS */
337 fcs = l2c_fcr_tx_get_fcs(p_buf);
338
339 /* Point to the end of the buffer and put the FCS there */
340 /*
341 * NOTE: Here we assume the allocated buffer is large enough
342 * to include extra L2CAP_FCS_LEN octets at the end.
343 */
344 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + p_buf->len;
345
346 UINT16_TO_STREAM(p, fcs);
347
348 p_buf->len += L2CAP_FCS_LEN;
349
350 if (is_retransmission) {
351 L2CAP_TRACE_EVENT(
352 "L2CAP eRTM ReTx I-frame CID: 0x%04x Len: %u SAR: %s TxSeq: %u "
353 "ReqSeq: %u F: %u",
354 p_ccb->local_cid, p_buf->len,
355 SAR_types[(ctrl_word & L2CAP_FCR_SAR_BITS) >> L2CAP_FCR_SAR_BITS_SHIFT],
356 (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT,
357 (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
358 (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
359 } else {
360 L2CAP_TRACE_EVENT(
361 "L2CAP eRTM Tx I-frame CID: 0x%04x Len: %u SAR: %-12s TxSeq: %u "
362 "ReqSeq: %u F: %u",
363 p_ccb->local_cid, p_buf->len,
364 SAR_types[(ctrl_word & L2CAP_FCR_SAR_BITS) >> L2CAP_FCR_SAR_BITS_SHIFT],
365 (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT,
366 (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
367 (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
368 }
369
370 /* Start the retransmission timer if not already running */
371 if (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE)
372 l2c_fcr_start_timer(p_ccb);
373 }
374
375 /*******************************************************************************
376 *
377 * Function l2c_fcr_send_S_frame
378 *
379 * Description This function formats and sends an S-frame for transmission.
380 *
381 * Returns -
382 *
383 ******************************************************************************/
l2c_fcr_send_S_frame(tL2C_CCB * p_ccb,uint16_t function_code,uint16_t pf_bit)384 void l2c_fcr_send_S_frame(tL2C_CCB* p_ccb, uint16_t function_code,
385 uint16_t pf_bit) {
386 CHECK(p_ccb != NULL);
387 uint8_t* p;
388 uint16_t ctrl_word;
389 uint16_t fcs;
390
391 if ((!p_ccb->in_use) || (p_ccb->chnl_state != CST_OPEN)) return;
392
393 if (pf_bit == L2CAP_FCR_P_BIT) {
394 p_ccb->fcrb.wait_ack = true;
395
396 l2c_fcr_stop_timer(p_ccb); /* Restart the monitor timer */
397 l2c_fcr_start_timer(p_ccb);
398 }
399
400 /* Create the control word to use */
401 ctrl_word = (function_code << L2CAP_FCR_SUP_SHIFT) | L2CAP_FCR_S_FRAME_BIT;
402 ctrl_word |= (p_ccb->fcrb.next_seq_expected << L2CAP_FCR_REQ_SEQ_BITS_SHIFT);
403 ctrl_word |= pf_bit;
404
405 BT_HDR* p_buf = (BT_HDR*)osi_malloc(L2CAP_CMD_BUF_SIZE);
406 p_buf->offset = HCI_DATA_PREAMBLE_SIZE;
407 p_buf->len = L2CAP_PKT_OVERHEAD + L2CAP_FCR_OVERHEAD;
408
409 /* Set the pointer to the beginning of the data */
410 p = (uint8_t*)(p_buf + 1) + p_buf->offset;
411
412 /* Put in the L2CAP header */
413 UINT16_TO_STREAM(p, L2CAP_FCR_OVERHEAD + L2CAP_FCS_LEN);
414 UINT16_TO_STREAM(p, p_ccb->remote_cid);
415 UINT16_TO_STREAM(p, ctrl_word);
416
417 /* Compute the FCS and add to the end of the buffer if not bypassed */
418 fcs = l2c_fcr_tx_get_fcs(p_buf);
419
420 UINT16_TO_STREAM(p, fcs);
421 p_buf->len += L2CAP_FCS_LEN;
422
423 /* Now, the HCI transport header */
424 p_buf->layer_specific = L2CAP_NON_FLUSHABLE_PKT;
425 l2cu_set_acl_hci_header(p_buf, p_ccb);
426
427 if ((((ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT) == 1) ||
428 (((ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT) == 3)) {
429 L2CAP_TRACE_WARNING(
430 "L2CAP eRTM Tx S-frame CID: 0x%04x ctrlword: 0x%04x Type: %s "
431 "ReqSeq: %u P: %u F: %u",
432 p_ccb->local_cid, ctrl_word,
433 SUP_types[(ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT],
434 (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
435 (ctrl_word & L2CAP_FCR_P_BIT) >> L2CAP_FCR_P_BIT_SHIFT,
436 (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
437 L2CAP_TRACE_WARNING(" Buf Len: %u", p_buf->len);
438 } else {
439 L2CAP_TRACE_EVENT(
440 "L2CAP eRTM Tx S-frame CID: 0x%04x ctrlword: 0x%04x Type: %s "
441 "ReqSeq: %u P: %u F: %u",
442 p_ccb->local_cid, ctrl_word,
443 SUP_types[(ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT],
444 (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
445 (ctrl_word & L2CAP_FCR_P_BIT) >> L2CAP_FCR_P_BIT_SHIFT,
446 (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
447 L2CAP_TRACE_EVENT(" Buf Len: %u", p_buf->len);
448 }
449
450 l2c_link_check_send_pkts(p_ccb->p_lcb, 0, p_buf);
451
452 p_ccb->fcrb.last_ack_sent = p_ccb->fcrb.next_seq_expected;
453
454 alarm_cancel(p_ccb->fcrb.ack_timer);
455 }
456
457 /*******************************************************************************
458 *
459 * Function l2c_fcr_proc_pdu
460 *
461 * Description This function is the entry point for processing of a
462 * received PDU when in flow control and/or retransmission
463 * modes.
464 *
465 * Returns -
466 *
467 ******************************************************************************/
l2c_fcr_proc_pdu(tL2C_CCB * p_ccb,BT_HDR * p_buf)468 void l2c_fcr_proc_pdu(tL2C_CCB* p_ccb, BT_HDR* p_buf) {
469 CHECK(p_ccb != NULL);
470 CHECK(p_buf != NULL);
471 uint8_t* p;
472 uint16_t fcs;
473 uint16_t min_pdu_len;
474 uint16_t ctrl_word;
475
476 /* Check the length */
477 min_pdu_len = (uint16_t)(L2CAP_FCS_LEN + L2CAP_FCR_OVERHEAD);
478
479 if (p_buf->len < min_pdu_len) {
480 L2CAP_TRACE_WARNING("Rx L2CAP PDU: CID: 0x%04x Len too short: %u",
481 p_ccb->local_cid, p_buf->len);
482 osi_free(p_buf);
483 return;
484 }
485
486 /* Get the control word */
487 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
488 STREAM_TO_UINT16(ctrl_word, p);
489
490 if (ctrl_word & L2CAP_FCR_S_FRAME_BIT) {
491 if ((((ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT) == 1) ||
492 (((ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT) == 3)) {
493 /* REJ or SREJ */
494 L2CAP_TRACE_WARNING(
495 "L2CAP eRTM Rx S-frame: cid: 0x%04x Len: %u Type: %s ReqSeq: %u "
496 "P: %u F: %u",
497 p_ccb->local_cid, p_buf->len,
498 SUP_types[(ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT],
499 (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
500 (ctrl_word & L2CAP_FCR_P_BIT) >> L2CAP_FCR_P_BIT_SHIFT,
501 (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
502 } else {
503 L2CAP_TRACE_EVENT(
504 "L2CAP eRTM Rx S-frame: cid: 0x%04x Len: %u Type: %s ReqSeq: %u "
505 "P: %u F: %u",
506 p_ccb->local_cid, p_buf->len,
507 SUP_types[(ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT],
508 (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
509 (ctrl_word & L2CAP_FCR_P_BIT) >> L2CAP_FCR_P_BIT_SHIFT,
510 (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
511 }
512 } else {
513 L2CAP_TRACE_EVENT(
514 "L2CAP eRTM Rx I-frame: cid: 0x%04x Len: %u SAR: %-12s TxSeq: %u "
515 "ReqSeq: %u F: %u",
516 p_ccb->local_cid, p_buf->len,
517 SAR_types[(ctrl_word & L2CAP_FCR_SAR_BITS) >> L2CAP_FCR_SAR_BITS_SHIFT],
518 (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT,
519 (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT,
520 (ctrl_word & L2CAP_FCR_F_BIT) >> L2CAP_FCR_F_BIT_SHIFT);
521 }
522
523 L2CAP_TRACE_EVENT(
524 " eRTM Rx Nxt_tx_seq %u, Lst_rx_ack %u, Nxt_seq_exp %u, Lst_ack_snt "
525 "%u, wt_q.cnt %u, tries %u",
526 p_ccb->fcrb.next_tx_seq, p_ccb->fcrb.last_rx_ack,
527 p_ccb->fcrb.next_seq_expected, p_ccb->fcrb.last_ack_sent,
528 fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q), p_ccb->fcrb.num_tries);
529
530 /* Verify FCS if using */
531 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + p_buf->len - L2CAP_FCS_LEN;
532
533 /* Extract and drop the FCS from the packet */
534 STREAM_TO_UINT16(fcs, p);
535 p_buf->len -= L2CAP_FCS_LEN;
536
537 if (l2c_fcr_rx_get_fcs(p_buf) != fcs) {
538 L2CAP_TRACE_WARNING("Rx L2CAP PDU: CID: 0x%04x BAD FCS", p_ccb->local_cid);
539 osi_free(p_buf);
540 return;
541 }
542
543 /* Get the control word */
544 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
545
546 STREAM_TO_UINT16(ctrl_word, p);
547
548 p_buf->len -= L2CAP_FCR_OVERHEAD;
549 p_buf->offset += L2CAP_FCR_OVERHEAD;
550
551 /* If we had a poll bit outstanding, check if we got a final response */
552 if (p_ccb->fcrb.wait_ack) {
553 /* If final bit not set, ignore the frame unless it is a polled S-frame */
554 if (!(ctrl_word & L2CAP_FCR_F_BIT)) {
555 if ((ctrl_word & L2CAP_FCR_P_BIT) &&
556 (ctrl_word & L2CAP_FCR_S_FRAME_BIT)) {
557 if (p_ccb->fcrb.srej_sent)
558 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_SREJ, L2CAP_FCR_F_BIT);
559 else
560 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, L2CAP_FCR_F_BIT);
561
562 /* Got a poll while in wait_ack state, so re-start our timer with
563 * 1-second */
564 /* This is a small optimization... the monitor timer is 12 secs, but we
565 * saw */
566 /* that if the other side sends us a poll when we are waiting for a
567 * final, */
568 /* then it speeds up recovery significantly if we poll it back soon
569 * after its poll. */
570 alarm_set_on_mloop(p_ccb->fcrb.mon_retrans_timer, BT_1SEC_TIMEOUT_MS,
571 l2c_ccb_timer_timeout, p_ccb);
572 }
573 osi_free(p_buf);
574 return;
575 }
576
577 p_ccb->fcrb.wait_ack = false;
578
579 /* P and F are mutually exclusive */
580 if (ctrl_word & L2CAP_FCR_S_FRAME_BIT) ctrl_word &= ~L2CAP_FCR_P_BIT;
581
582 if (fixed_queue_is_empty(p_ccb->fcrb.waiting_for_ack_q))
583 p_ccb->fcrb.num_tries = 0;
584
585 l2c_fcr_stop_timer(p_ccb);
586 } else {
587 /* Otherwise, ensure the final bit is ignored */
588 ctrl_word &= ~L2CAP_FCR_F_BIT;
589 }
590
591 /* Process receive sequence number */
592 if (!process_reqseq(p_ccb, ctrl_word)) {
593 osi_free(p_buf);
594 return;
595 }
596
597 /* Process based on whether it is an S-frame or an I-frame */
598 if (ctrl_word & L2CAP_FCR_S_FRAME_BIT)
599 process_s_frame(p_ccb, p_buf, ctrl_word);
600 else
601 process_i_frame(p_ccb, p_buf, ctrl_word, false);
602
603 /* Return if the channel got disconnected by a bad packet or max
604 * retransmissions */
605 if ((!p_ccb->in_use) || (p_ccb->chnl_state != CST_OPEN)) return;
606
607 /* If we have some buffers held while doing SREJ, and SREJ has cleared,
608 * process them now */
609 if ((!p_ccb->fcrb.srej_sent) &&
610 (!fixed_queue_is_empty(p_ccb->fcrb.srej_rcv_hold_q))) {
611 fixed_queue_t* temp_q = p_ccb->fcrb.srej_rcv_hold_q;
612 p_ccb->fcrb.srej_rcv_hold_q = fixed_queue_new(SIZE_MAX);
613
614 while ((p_buf = (BT_HDR*)fixed_queue_try_dequeue(temp_q)) != NULL) {
615 if (p_ccb->in_use && (p_ccb->chnl_state == CST_OPEN)) {
616 /* Get the control word */
617 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset - L2CAP_FCR_OVERHEAD;
618
619 STREAM_TO_UINT16(ctrl_word, p);
620
621 L2CAP_TRACE_DEBUG(
622 "l2c_fcr_proc_pdu() CID: 0x%04x Process Buffer from SREJ_Hold_Q "
623 "TxSeq: %u Expected_Seq: %u",
624 p_ccb->local_cid,
625 (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT,
626 p_ccb->fcrb.next_seq_expected);
627
628 /* Process the SREJ held I-frame, but do not send an RR for each
629 * individual frame */
630 process_i_frame(p_ccb, p_buf, ctrl_word, true);
631 } else
632 osi_free(p_buf);
633
634 /* If more frames were lost during SREJ, send a REJ */
635 if (p_ccb->fcrb.rej_after_srej) {
636 p_ccb->fcrb.rej_after_srej = false;
637 p_ccb->fcrb.rej_sent = true;
638
639 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_REJ, 0);
640 }
641 }
642 fixed_queue_free(temp_q, NULL);
643
644 /* Now, if needed, send one RR for the whole held queue */
645 if ((!p_ccb->fcrb.rej_sent) && (!p_ccb->fcrb.srej_sent) &&
646 (p_ccb->fcrb.next_seq_expected != p_ccb->fcrb.last_ack_sent))
647 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, 0);
648 else {
649 L2CAP_TRACE_DEBUG(
650 "l2c_fcr_proc_pdu() not sending RR CID: 0x%04x local_busy:%d "
651 "rej_sent:%d srej_sent:%d Expected_Seq:%u Last_Ack:%u",
652 p_ccb->local_cid, 0, p_ccb->fcrb.rej_sent, p_ccb->fcrb.srej_sent,
653 p_ccb->fcrb.next_seq_expected, p_ccb->fcrb.last_ack_sent);
654 }
655 }
656
657 /* If a window has opened, check if we can send any more packets */
658 if ((!fixed_queue_is_empty(p_ccb->fcrb.retrans_q) ||
659 !fixed_queue_is_empty(p_ccb->xmit_hold_q)) &&
660 (!p_ccb->fcrb.wait_ack) && (!l2c_fcr_is_flow_controlled(p_ccb))) {
661 l2c_link_check_send_pkts(p_ccb->p_lcb, 0, NULL);
662 }
663 }
664
665 /*******************************************************************************
666 *
667 * Function l2c_lcc_proc_pdu
668 *
669 * Description This function is the entry point for processing of a
670 * received PDU when in LE Coc flow control modes.
671 *
672 * Returns -
673 *
674 ******************************************************************************/
l2c_lcc_proc_pdu(tL2C_CCB * p_ccb,BT_HDR * p_buf)675 void l2c_lcc_proc_pdu(tL2C_CCB* p_ccb, BT_HDR* p_buf) {
676 CHECK(p_ccb != NULL);
677 CHECK(p_buf != NULL);
678 uint8_t* p = (uint8_t*)(p_buf + 1) + p_buf->offset;
679 uint16_t sdu_length;
680 BT_HDR* p_data = NULL;
681
682 /* Buffer length should not exceed local mps */
683 if (p_buf->len > p_ccb->local_conn_cfg.mps) {
684 LOG_ERROR("buffer length=%d exceeds local mps=%d. Drop and disconnect.",
685 p_buf->len, p_ccb->local_conn_cfg.mps);
686
687 /* Discard the buffer and disconnect*/
688 osi_free(p_buf);
689 l2cu_disconnect_chnl(p_ccb);
690 return;
691 }
692
693 if (p_ccb->is_first_seg) {
694 if (p_buf->len < sizeof(sdu_length)) {
695 L2CAP_TRACE_ERROR("%s: buffer length=%d too small. Need at least 2.",
696 __func__, p_buf->len);
697 /* Discard the buffer */
698 osi_free(p_buf);
699 return;
700 }
701 STREAM_TO_UINT16(sdu_length, p);
702
703 /* Check the SDU Length with local MTU size */
704 if (sdu_length > p_ccb->local_conn_cfg.mtu) {
705 LOG_ERROR("sdu length=%d exceeds local mtu=%d. Drop and disconnect.",
706 sdu_length, p_ccb->local_conn_cfg.mtu);
707 /* Discard the buffer and disconnect*/
708 osi_free(p_buf);
709 l2cu_disconnect_chnl(p_ccb);
710 return;
711 }
712
713 p_buf->len -= sizeof(sdu_length);
714 p_buf->offset += sizeof(sdu_length);
715
716 if (sdu_length < p_buf->len) {
717 L2CAP_TRACE_ERROR("%s: Invalid sdu_length: %d", __func__, sdu_length);
718 /* Discard the buffer */
719 osi_free(p_buf);
720 return;
721 }
722
723 p_data = (BT_HDR*)osi_malloc(BT_HDR_SIZE + sdu_length);
724 if (p_data == NULL) {
725 osi_free(p_buf);
726 return;
727 }
728
729 p_ccb->ble_sdu = p_data;
730 p_data->len = 0;
731 p_ccb->ble_sdu_length = sdu_length;
732 L2CAP_TRACE_DEBUG("%s SDU Length = %d", __func__, sdu_length);
733 p_data->offset = 0;
734
735 } else {
736 p_data = p_ccb->ble_sdu;
737 if (p_data == NULL) {
738 osi_free(p_buf);
739 return;
740 }
741 if (p_buf->len > (p_ccb->ble_sdu_length - p_data->len)) {
742 L2CAP_TRACE_ERROR("%s: buffer length=%d too big. max=%d. Dropped",
743 __func__, p_data->len,
744 (p_ccb->ble_sdu_length - p_data->len));
745 osi_free(p_buf);
746
747 /* Throw away all pending fragments and disconnects */
748 p_ccb->is_first_seg = true;
749 osi_free(p_ccb->ble_sdu);
750 p_ccb->ble_sdu = NULL;
751 p_ccb->ble_sdu_length = 0;
752 l2cu_disconnect_chnl(p_ccb);
753 return;
754 }
755 }
756
757 memcpy((uint8_t*)(p_data + 1) + p_data->offset + p_data->len,
758 (uint8_t*)(p_buf + 1) + p_buf->offset, p_buf->len);
759 p_data->len += p_buf->len;
760 p = (uint8_t*)(p_data + 1) + p_data->offset;
761 if (p_data->len == p_ccb->ble_sdu_length) {
762 l2c_csm_execute(p_ccb, L2CEVT_L2CAP_DATA, p_data);
763 p_ccb->is_first_seg = true;
764 p_ccb->ble_sdu = NULL;
765 p_ccb->ble_sdu_length = 0;
766 } else if (p_data->len < p_ccb->ble_sdu_length) {
767 p_ccb->is_first_seg = false;
768 }
769
770 osi_free(p_buf);
771 return;
772 }
773
774 /*******************************************************************************
775 *
776 * Function l2c_fcr_proc_tout
777 *
778 * Description Handle a timeout. We should be in error recovery state.
779 *
780 * Returns -
781 *
782 ******************************************************************************/
l2c_fcr_proc_tout(tL2C_CCB * p_ccb)783 void l2c_fcr_proc_tout(tL2C_CCB* p_ccb) {
784 CHECK(p_ccb != NULL);
785 L2CAP_TRACE_DEBUG(
786 "l2c_fcr_proc_tout: CID: 0x%04x num_tries: %u (max: %u) wait_ack: %u "
787 "ack_q_count: %u",
788 p_ccb->local_cid, p_ccb->fcrb.num_tries, p_ccb->peer_cfg.fcr.max_transmit,
789 p_ccb->fcrb.wait_ack, fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q));
790
791 if ((p_ccb->peer_cfg.fcr.max_transmit != 0) &&
792 (++p_ccb->fcrb.num_tries > p_ccb->peer_cfg.fcr.max_transmit)) {
793 l2cu_disconnect_chnl(p_ccb);
794 } else {
795 if (!p_ccb->fcrb.srej_sent && !p_ccb->fcrb.rej_sent) {
796 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, L2CAP_FCR_P_BIT);
797 }
798 }
799 }
800
801 /*******************************************************************************
802 *
803 * Function l2c_fcr_proc_ack_tout
804 *
805 * Description Send RR/RNR if we have not acked I frame
806 *
807 * Returns -
808 *
809 ******************************************************************************/
l2c_fcr_proc_ack_tout(tL2C_CCB * p_ccb)810 void l2c_fcr_proc_ack_tout(tL2C_CCB* p_ccb) {
811 CHECK(p_ccb != NULL);
812 L2CAP_TRACE_DEBUG(
813 "l2c_fcr_proc_ack_tout: CID: 0x%04x State: %u Wack:%u Rq:%d Acked:%d",
814 p_ccb->local_cid, p_ccb->chnl_state, p_ccb->fcrb.wait_ack,
815 p_ccb->fcrb.next_seq_expected, p_ccb->fcrb.last_ack_sent);
816
817 if ((p_ccb->chnl_state == CST_OPEN) && (!p_ccb->fcrb.wait_ack) &&
818 (p_ccb->fcrb.last_ack_sent != p_ccb->fcrb.next_seq_expected)) {
819 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, 0);
820 }
821 }
822
823 /*******************************************************************************
824 *
825 * Function process_reqseq
826 *
827 * Description Handle receive sequence number
828 *
829 * Returns -
830 *
831 ******************************************************************************/
process_reqseq(tL2C_CCB * p_ccb,uint16_t ctrl_word)832 static bool process_reqseq(tL2C_CCB* p_ccb, uint16_t ctrl_word) {
833 CHECK(p_ccb != NULL);
834 tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
835 uint8_t req_seq, num_bufs_acked, xx;
836 uint16_t ls;
837 uint16_t full_sdus_xmitted;
838
839 /* Receive sequence number does not ack anything for SREJ with P-bit set to
840 * zero */
841 if ((ctrl_word & L2CAP_FCR_S_FRAME_BIT) &&
842 ((ctrl_word & L2CAP_FCR_SUP_BITS) ==
843 (L2CAP_FCR_SUP_SREJ << L2CAP_FCR_SUP_SHIFT)) &&
844 ((ctrl_word & L2CAP_FCR_P_BIT) == 0)) {
845 /* If anything still waiting for ack, restart the timer if it was stopped */
846 if (!fixed_queue_is_empty(p_fcrb->waiting_for_ack_q))
847 l2c_fcr_start_timer(p_ccb);
848
849 return (true);
850 }
851
852 /* Extract the receive sequence number from the control word */
853 req_seq =
854 (ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >> L2CAP_FCR_REQ_SEQ_BITS_SHIFT;
855
856 num_bufs_acked = (req_seq - p_fcrb->last_rx_ack) & L2CAP_FCR_SEQ_MODULO;
857
858 /* Verify the request sequence is in range before proceeding */
859 if (num_bufs_acked > fixed_queue_length(p_fcrb->waiting_for_ack_q)) {
860 /* The channel is closed if ReqSeq is not in range */
861 L2CAP_TRACE_WARNING(
862 "L2CAP eRTM Frame BAD Req_Seq - ctrl_word: 0x%04x req_seq 0x%02x "
863 "last_rx_ack: 0x%02x QCount: %u",
864 ctrl_word, req_seq, p_fcrb->last_rx_ack,
865 fixed_queue_length(p_fcrb->waiting_for_ack_q));
866
867 l2cu_disconnect_chnl(p_ccb);
868 return (false);
869 }
870
871 p_fcrb->last_rx_ack = req_seq;
872
873 /* Now we can release all acknowledged frames, and restart the retransmission
874 * timer if needed */
875 if (num_bufs_acked != 0) {
876 p_fcrb->num_tries = 0;
877 full_sdus_xmitted = 0;
878
879 for (xx = 0; xx < num_bufs_acked; xx++) {
880 BT_HDR* p_tmp =
881 (BT_HDR*)fixed_queue_try_dequeue(p_fcrb->waiting_for_ack_q);
882 ls = p_tmp->layer_specific & L2CAP_FCR_SAR_BITS;
883
884 if ((ls == L2CAP_FCR_UNSEG_SDU) || (ls == L2CAP_FCR_END_SDU))
885 full_sdus_xmitted++;
886
887 osi_free(p_tmp);
888 }
889
890 /* If we are still in a wait_ack state, do not mess with the timer */
891 if (!p_ccb->fcrb.wait_ack) l2c_fcr_stop_timer(p_ccb);
892
893 /* Check if we need to call the "packet_sent" callback */
894 if ((p_ccb->p_rcb) && (p_ccb->p_rcb->api.pL2CA_TxComplete_Cb) &&
895 (full_sdus_xmitted)) {
896 /* Special case for eRTM, if all packets sent, send 0xFFFF */
897 if (fixed_queue_is_empty(p_fcrb->waiting_for_ack_q) &&
898 fixed_queue_is_empty(p_ccb->xmit_hold_q)) {
899 full_sdus_xmitted = 0xFFFF;
900 }
901
902 (*p_ccb->p_rcb->api.pL2CA_TxComplete_Cb)(p_ccb->local_cid,
903 full_sdus_xmitted);
904 }
905 }
906
907 /* If anything still waiting for ack, restart the timer if it was stopped */
908 if (!fixed_queue_is_empty(p_fcrb->waiting_for_ack_q))
909 l2c_fcr_start_timer(p_ccb);
910 return (true);
911 }
912
913 /*******************************************************************************
914 *
915 * Function process_s_frame
916 *
917 * Description Process an S frame
918 *
919 * Returns -
920 *
921 ******************************************************************************/
process_s_frame(tL2C_CCB * p_ccb,BT_HDR * p_buf,uint16_t ctrl_word)922 static void process_s_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf,
923 uint16_t ctrl_word) {
924 CHECK(p_ccb != NULL);
925 CHECK(p_buf != NULL);
926
927 tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
928 uint16_t s_frame_type =
929 (ctrl_word & L2CAP_FCR_SUP_BITS) >> L2CAP_FCR_SUP_SHIFT;
930 bool remote_was_busy;
931 bool all_ok = true;
932
933 if (p_buf->len != 0) {
934 L2CAP_TRACE_WARNING("Incorrect S-frame Length (%d)", p_buf->len);
935 }
936
937 L2CAP_TRACE_DEBUG("process_s_frame ctrl_word 0x%04x fcrb_remote_busy:%d",
938 ctrl_word, p_fcrb->remote_busy);
939
940 if (ctrl_word & L2CAP_FCR_P_BIT) {
941 p_fcrb->rej_sent = false; /* After checkpoint, we can send anoher REJ */
942 p_fcrb->send_f_rsp = true; /* Set a flag in case an I-frame is pending */
943 }
944
945 switch (s_frame_type) {
946 case L2CAP_FCR_SUP_RR:
947 remote_was_busy = p_fcrb->remote_busy;
948 p_fcrb->remote_busy = false;
949
950 if ((ctrl_word & L2CAP_FCR_F_BIT) || (remote_was_busy))
951 all_ok = retransmit_i_frames(p_ccb, L2C_FCR_RETX_ALL_PKTS);
952 break;
953
954 case L2CAP_FCR_SUP_REJ:
955 p_fcrb->remote_busy = false;
956 all_ok = retransmit_i_frames(p_ccb, L2C_FCR_RETX_ALL_PKTS);
957 break;
958
959 case L2CAP_FCR_SUP_RNR:
960 p_fcrb->remote_busy = true;
961 l2c_fcr_stop_timer(p_ccb);
962 break;
963
964 case L2CAP_FCR_SUP_SREJ:
965 p_fcrb->remote_busy = false;
966 all_ok = retransmit_i_frames(
967 p_ccb, (uint8_t)((ctrl_word & L2CAP_FCR_REQ_SEQ_BITS) >>
968 L2CAP_FCR_REQ_SEQ_BITS_SHIFT));
969 break;
970 }
971
972 if (all_ok) {
973 /* If polled, we need to respond with F-bit. Note, we may have sent a
974 * I-frame with the F-bit */
975 if (p_fcrb->send_f_rsp) {
976 if (p_fcrb->srej_sent)
977 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_SREJ, L2CAP_FCR_F_BIT);
978 else
979 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, L2CAP_FCR_F_BIT);
980
981 p_fcrb->send_f_rsp = false;
982 }
983 } else {
984 L2CAP_TRACE_DEBUG("process_s_frame hit_max_retries");
985 }
986
987 osi_free(p_buf);
988 }
989
990 /*******************************************************************************
991 *
992 * Function process_i_frame
993 *
994 * Description Process an I frame
995 *
996 * Returns -
997 *
998 ******************************************************************************/
process_i_frame(tL2C_CCB * p_ccb,BT_HDR * p_buf,uint16_t ctrl_word,bool delay_ack)999 static void process_i_frame(tL2C_CCB* p_ccb, BT_HDR* p_buf, uint16_t ctrl_word,
1000 bool delay_ack) {
1001 CHECK(p_ccb != NULL);
1002 CHECK(p_buf != NULL);
1003
1004 tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
1005 uint8_t tx_seq, num_lost, num_to_ack, next_srej;
1006
1007 /* If we were doing checkpoint recovery, first retransmit all unacked I-frames
1008 */
1009 if (ctrl_word & L2CAP_FCR_F_BIT) {
1010 if (!retransmit_i_frames(p_ccb, L2C_FCR_RETX_ALL_PKTS)) {
1011 osi_free(p_buf);
1012 return;
1013 }
1014 }
1015
1016 /* Extract the sequence number */
1017 tx_seq = (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT;
1018
1019 /* Check if tx-sequence is the expected one */
1020 if (tx_seq != p_fcrb->next_seq_expected) {
1021 num_lost = (tx_seq - p_fcrb->next_seq_expected) & L2CAP_FCR_SEQ_MODULO;
1022
1023 /* Is the frame a duplicate ? If so, just drop it */
1024 if (num_lost >= p_ccb->our_cfg.fcr.tx_win_sz) {
1025 /* Duplicate - simply drop it */
1026 L2CAP_TRACE_WARNING(
1027 "process_i_frame() Dropping Duplicate Frame tx_seq:%u ExpectedTxSeq "
1028 "%u",
1029 tx_seq, p_fcrb->next_seq_expected);
1030 osi_free(p_buf);
1031 } else {
1032 L2CAP_TRACE_WARNING(
1033 "process_i_frame() CID: 0x%04x Lost: %u tx_seq:%u ExpTxSeq %u "
1034 "Rej: %u SRej: %u",
1035 p_ccb->local_cid, num_lost, tx_seq, p_fcrb->next_seq_expected,
1036 p_fcrb->rej_sent, p_fcrb->srej_sent);
1037
1038 if (p_fcrb->srej_sent) {
1039 /* If SREJ sent, save the frame for later processing as long as it is in
1040 * sequence */
1041 next_srej =
1042 (((BT_HDR*)fixed_queue_try_peek_last(p_fcrb->srej_rcv_hold_q))
1043 ->layer_specific +
1044 1) &
1045 L2CAP_FCR_SEQ_MODULO;
1046
1047 if ((tx_seq == next_srej) &&
1048 (fixed_queue_length(p_fcrb->srej_rcv_hold_q) <
1049 p_ccb->our_cfg.fcr.tx_win_sz)) {
1050 L2CAP_TRACE_DEBUG(
1051 "process_i_frame() Lost: %u tx_seq:%u ExpTxSeq %u Rej: %u "
1052 "SRej1",
1053 num_lost, tx_seq, p_fcrb->next_seq_expected, p_fcrb->rej_sent);
1054
1055 p_buf->layer_specific = tx_seq;
1056 fixed_queue_enqueue(p_fcrb->srej_rcv_hold_q, p_buf);
1057 } else {
1058 L2CAP_TRACE_WARNING(
1059 "process_i_frame() CID: 0x%04x frame dropped in Srej Sent "
1060 "next_srej:%u hold_q.count:%u win_sz:%u",
1061 p_ccb->local_cid, next_srej,
1062 fixed_queue_length(p_fcrb->srej_rcv_hold_q),
1063 p_ccb->our_cfg.fcr.tx_win_sz);
1064
1065 p_fcrb->rej_after_srej = true;
1066 osi_free(p_buf);
1067 }
1068 } else if (p_fcrb->rej_sent) {
1069 L2CAP_TRACE_WARNING(
1070 "process_i_frame() CID: 0x%04x Lost: %u tx_seq:%u ExpTxSeq %u "
1071 "Rej: 1 SRej: %u",
1072 p_ccb->local_cid, num_lost, tx_seq, p_fcrb->next_seq_expected,
1073 p_fcrb->srej_sent);
1074
1075 /* If REJ sent, just drop the frame */
1076 osi_free(p_buf);
1077 } else {
1078 L2CAP_TRACE_DEBUG(
1079 "process_i_frame() CID: 0x%04x tx_seq:%u ExpTxSeq %u Rej: %u",
1080 p_ccb->local_cid, tx_seq, p_fcrb->next_seq_expected,
1081 p_fcrb->rej_sent);
1082
1083 /* If only one lost, we will send SREJ, otherwise we will send REJ */
1084 if (num_lost > 1) {
1085 osi_free(p_buf);
1086 p_fcrb->rej_sent = true;
1087 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_REJ, 0);
1088 } else {
1089 if (!fixed_queue_is_empty(p_fcrb->srej_rcv_hold_q)) {
1090 L2CAP_TRACE_ERROR(
1091 "process_i_frame() CID: 0x%04x sending SREJ tx_seq:%d "
1092 "hold_q.count:%u",
1093 p_ccb->local_cid, tx_seq,
1094 fixed_queue_length(p_fcrb->srej_rcv_hold_q));
1095 }
1096 p_buf->layer_specific = tx_seq;
1097 fixed_queue_enqueue(p_fcrb->srej_rcv_hold_q, p_buf);
1098 p_fcrb->srej_sent = true;
1099 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_SREJ, 0);
1100 }
1101 alarm_cancel(p_ccb->fcrb.ack_timer);
1102 }
1103 }
1104 return;
1105 }
1106
1107 /* Seq number is the next expected. Clear possible reject exception in case it
1108 * occured */
1109 p_fcrb->rej_sent = p_fcrb->srej_sent = false;
1110
1111 /* Adjust the next_seq, so that if the upper layer sends more data in the
1112 callback
1113 context, the received frame is acked by an I-frame. */
1114 p_fcrb->next_seq_expected = (tx_seq + 1) & L2CAP_FCR_SEQ_MODULO;
1115
1116 /* If any SAR problem in eRTM mode, spec says disconnect. */
1117 if (!do_sar_reassembly(p_ccb, p_buf, ctrl_word)) {
1118 L2CAP_TRACE_WARNING("process_i_frame() CID: 0x%04x reassembly failed",
1119 p_ccb->local_cid);
1120 l2cu_disconnect_chnl(p_ccb);
1121 return;
1122 }
1123
1124 /* RR optimization - if peer can still send us more, then start an ACK timer
1125 */
1126 num_to_ack = (p_fcrb->next_seq_expected - p_fcrb->last_ack_sent) &
1127 L2CAP_FCR_SEQ_MODULO;
1128
1129 if (num_to_ack < p_ccb->fcrb.max_held_acks) delay_ack = true;
1130
1131 /* We should neve never ack frame if we are not in OPEN state */
1132 if ((num_to_ack != 0) && p_ccb->in_use && (p_ccb->chnl_state == CST_OPEN)) {
1133 /* If no frames are awaiting transmission or are held, send an RR or RNR
1134 * S-frame for ack */
1135 if (delay_ack) {
1136 /* If it is the first I frame we did not ack, start ack timer */
1137 if (!alarm_is_scheduled(p_ccb->fcrb.ack_timer)) {
1138 alarm_set_on_mloop(p_ccb->fcrb.ack_timer, L2CAP_FCR_ACK_TIMEOUT_MS,
1139 l2c_fcrb_ack_timer_timeout, p_ccb);
1140 }
1141 } else if ((fixed_queue_is_empty(p_ccb->xmit_hold_q) ||
1142 l2c_fcr_is_flow_controlled(p_ccb)) &&
1143 fixed_queue_is_empty(p_ccb->fcrb.srej_rcv_hold_q)) {
1144 l2c_fcr_send_S_frame(p_ccb, L2CAP_FCR_SUP_RR, 0);
1145 }
1146 }
1147 }
1148
1149 /*******************************************************************************
1150 *
1151 * Function do_sar_reassembly
1152 *
1153 * Description Process SAR bits and re-assemble frame
1154 *
1155 * Returns true if all OK, else false
1156 *
1157 ******************************************************************************/
do_sar_reassembly(tL2C_CCB * p_ccb,BT_HDR * p_buf,uint16_t ctrl_word)1158 static bool do_sar_reassembly(tL2C_CCB* p_ccb, BT_HDR* p_buf,
1159 uint16_t ctrl_word) {
1160 CHECK(p_ccb != NULL);
1161 CHECK(p_buf != NULL);
1162
1163 tL2C_FCRB* p_fcrb = &p_ccb->fcrb;
1164 uint16_t sar_type = ctrl_word & L2CAP_FCR_SEG_BITS;
1165 bool packet_ok = true;
1166 uint8_t* p;
1167
1168 /* Check if the SAR state is correct */
1169 if ((sar_type == L2CAP_FCR_UNSEG_SDU) || (sar_type == L2CAP_FCR_START_SDU)) {
1170 if (p_fcrb->p_rx_sdu != NULL) {
1171 L2CAP_TRACE_WARNING(
1172 "SAR - got unexpected unsegmented or start SDU Expected len: %u "
1173 "Got so far: %u",
1174 p_fcrb->rx_sdu_len, p_fcrb->p_rx_sdu->len);
1175
1176 packet_ok = false;
1177 }
1178 /* Check the length of the packet */
1179 if ((sar_type == L2CAP_FCR_START_SDU) &&
1180 (p_buf->len < L2CAP_SDU_LEN_OVERHEAD)) {
1181 L2CAP_TRACE_WARNING("SAR start packet too short: %u", p_buf->len);
1182 packet_ok = false;
1183 }
1184 } else {
1185 if (p_fcrb->p_rx_sdu == NULL) {
1186 L2CAP_TRACE_WARNING("SAR - got unexpected cont or end SDU");
1187 packet_ok = false;
1188 }
1189 }
1190
1191 if ((packet_ok) && (sar_type != L2CAP_FCR_UNSEG_SDU)) {
1192 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset;
1193
1194 /* For start SDU packet, extract the SDU length */
1195 if (sar_type == L2CAP_FCR_START_SDU) {
1196 /* Get the SDU length */
1197 STREAM_TO_UINT16(p_fcrb->rx_sdu_len, p);
1198 p_buf->offset += 2;
1199 p_buf->len -= 2;
1200
1201 if (p_fcrb->rx_sdu_len > p_ccb->max_rx_mtu) {
1202 L2CAP_TRACE_WARNING("SAR - SDU len: %u larger than MTU: %u",
1203 p_fcrb->rx_sdu_len, p_ccb->max_rx_mtu);
1204 packet_ok = false;
1205 } else {
1206 p_fcrb->p_rx_sdu = (BT_HDR*)osi_malloc(
1207 BT_HDR_SIZE + OBX_BUF_MIN_OFFSET + p_fcrb->rx_sdu_len);
1208 p_fcrb->p_rx_sdu->offset = OBX_BUF_MIN_OFFSET;
1209 p_fcrb->p_rx_sdu->len = 0;
1210 }
1211 }
1212
1213 if (packet_ok) {
1214 if ((p_fcrb->p_rx_sdu->len + p_buf->len) > p_fcrb->rx_sdu_len) {
1215 L2CAP_TRACE_ERROR(
1216 "SAR - SDU len exceeded Type: %u Lengths: %u %u %u", sar_type,
1217 p_fcrb->p_rx_sdu->len, p_buf->len, p_fcrb->rx_sdu_len);
1218 packet_ok = false;
1219 } else if ((sar_type == L2CAP_FCR_END_SDU) &&
1220 ((p_fcrb->p_rx_sdu->len + p_buf->len) != p_fcrb->rx_sdu_len)) {
1221 L2CAP_TRACE_WARNING("SAR - SDU end rcvd but SDU incomplete: %u %u %u",
1222 p_fcrb->p_rx_sdu->len, p_buf->len,
1223 p_fcrb->rx_sdu_len);
1224 packet_ok = false;
1225 } else {
1226 memcpy(((uint8_t*)(p_fcrb->p_rx_sdu + 1)) + p_fcrb->p_rx_sdu->offset +
1227 p_fcrb->p_rx_sdu->len,
1228 p, p_buf->len);
1229
1230 p_fcrb->p_rx_sdu->len += p_buf->len;
1231
1232 osi_free(p_buf);
1233 p_buf = NULL;
1234
1235 if (sar_type == L2CAP_FCR_END_SDU) {
1236 p_buf = p_fcrb->p_rx_sdu;
1237 p_fcrb->p_rx_sdu = NULL;
1238 }
1239 }
1240 }
1241 }
1242
1243 if (!packet_ok) {
1244 osi_free(p_buf);
1245 } else if (p_buf != NULL) {
1246 if (p_ccb->local_cid < L2CAP_BASE_APPL_CID &&
1247 (p_ccb->local_cid >= L2CAP_FIRST_FIXED_CHNL &&
1248 p_ccb->local_cid <= L2CAP_LAST_FIXED_CHNL)) {
1249 if (l2cb.fixed_reg[p_ccb->local_cid - L2CAP_FIRST_FIXED_CHNL]
1250 .pL2CA_FixedData_Cb)
1251 (*l2cb.fixed_reg[p_ccb->local_cid - L2CAP_FIRST_FIXED_CHNL]
1252 .pL2CA_FixedData_Cb)(p_ccb->local_cid,
1253 p_ccb->p_lcb->remote_bd_addr, p_buf);
1254 } else
1255 l2c_csm_execute(p_ccb, L2CEVT_L2CAP_DATA, p_buf);
1256 }
1257
1258 return (packet_ok);
1259 }
1260
1261 /*******************************************************************************
1262 *
1263 * Function retransmit_i_frames
1264 *
1265 * Description This function retransmits i-frames awaiting acks.
1266 *
1267 * Returns bool - true if retransmitted
1268 *
1269 ******************************************************************************/
retransmit_i_frames(tL2C_CCB * p_ccb,uint8_t tx_seq)1270 static bool retransmit_i_frames(tL2C_CCB* p_ccb, uint8_t tx_seq) {
1271 CHECK(p_ccb != NULL);
1272
1273 BT_HDR* p_buf = NULL;
1274 uint8_t* p;
1275 uint8_t buf_seq;
1276 uint16_t ctrl_word;
1277
1278 if ((!fixed_queue_is_empty(p_ccb->fcrb.waiting_for_ack_q)) &&
1279 (p_ccb->peer_cfg.fcr.max_transmit != 0) &&
1280 (p_ccb->fcrb.num_tries >= p_ccb->peer_cfg.fcr.max_transmit)) {
1281 L2CAP_TRACE_EVENT(
1282 "Max Tries Exceeded: (last_acq: %d CID: 0x%04x num_tries: %u (max: "
1283 "%u) ack_q_count: %u",
1284 p_ccb->fcrb.last_rx_ack, p_ccb->local_cid, p_ccb->fcrb.num_tries,
1285 p_ccb->peer_cfg.fcr.max_transmit,
1286 fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q));
1287
1288 l2cu_disconnect_chnl(p_ccb);
1289 return (false);
1290 }
1291
1292 /* tx_seq indicates whether to retransmit a specific sequence or all (if ==
1293 * L2C_FCR_RETX_ALL_PKTS) */
1294 list_t* list_ack = NULL;
1295 const list_node_t* node_ack = NULL;
1296 if (!fixed_queue_is_empty(p_ccb->fcrb.waiting_for_ack_q)) {
1297 list_ack = fixed_queue_get_list(p_ccb->fcrb.waiting_for_ack_q);
1298 node_ack = list_begin(list_ack);
1299 }
1300 if (tx_seq != L2C_FCR_RETX_ALL_PKTS) {
1301 /* If sending only one, the sequence number tells us which one. Look for it.
1302 */
1303 if (list_ack != NULL) {
1304 for (; node_ack != list_end(list_ack); node_ack = list_next(node_ack)) {
1305 p_buf = (BT_HDR*)list_node(node_ack);
1306 /* Get the old control word */
1307 p = ((uint8_t*)(p_buf + 1)) + p_buf->offset + L2CAP_PKT_OVERHEAD;
1308
1309 STREAM_TO_UINT16(ctrl_word, p);
1310
1311 buf_seq =
1312 (ctrl_word & L2CAP_FCR_TX_SEQ_BITS) >> L2CAP_FCR_TX_SEQ_BITS_SHIFT;
1313
1314 L2CAP_TRACE_DEBUG(
1315 "retransmit_i_frames() cur seq: %u looking for: %u", buf_seq,
1316 tx_seq);
1317
1318 if (tx_seq == buf_seq) break;
1319 }
1320 }
1321
1322 if (!p_buf) {
1323 L2CAP_TRACE_ERROR("retransmit_i_frames() UNKNOWN seq: %u q_count: %u",
1324 tx_seq,
1325 fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q));
1326 return (true);
1327 }
1328 } else {
1329 // Iterate though list and flush the amount requested from
1330 // the transmit data queue that satisfy the layer and event conditions.
1331 for (list_node_t* node_tmp = list_begin(p_ccb->p_lcb->link_xmit_data_q);
1332 node_tmp != list_end(p_ccb->p_lcb->link_xmit_data_q);) {
1333 BT_HDR* p_tmp = (BT_HDR*)list_node(node_tmp);
1334 node_tmp = list_next(node_tmp);
1335
1336 /* Do not flush other CIDs or partial segments */
1337 if ((p_tmp->layer_specific == 0) && (p_tmp->event == p_ccb->local_cid)) {
1338 list_remove(p_ccb->p_lcb->link_xmit_data_q, p_tmp);
1339 osi_free(p_tmp);
1340 }
1341 }
1342
1343 /* Also flush our retransmission queue */
1344 while (!fixed_queue_is_empty(p_ccb->fcrb.retrans_q))
1345 osi_free(fixed_queue_try_dequeue(p_ccb->fcrb.retrans_q));
1346
1347 if (list_ack != NULL) node_ack = list_begin(list_ack);
1348 }
1349
1350 if (list_ack != NULL) {
1351 while (node_ack != list_end(list_ack)) {
1352 p_buf = (BT_HDR*)list_node(node_ack);
1353 node_ack = list_next(node_ack);
1354
1355 BT_HDR* p_buf2 = l2c_fcr_clone_buf(p_buf, p_buf->offset, p_buf->len);
1356 if (p_buf2) {
1357 p_buf2->layer_specific = p_buf->layer_specific;
1358
1359 fixed_queue_enqueue(p_ccb->fcrb.retrans_q, p_buf2);
1360 }
1361
1362 if ((tx_seq != L2C_FCR_RETX_ALL_PKTS) || (p_buf2 == NULL)) break;
1363 }
1364 }
1365
1366 l2c_link_check_send_pkts(p_ccb->p_lcb, 0, NULL);
1367
1368 if (fixed_queue_length(p_ccb->fcrb.waiting_for_ack_q)) {
1369 p_ccb->fcrb.num_tries++;
1370 l2c_fcr_start_timer(p_ccb);
1371 }
1372
1373 return (true);
1374 }
1375
1376 /*******************************************************************************
1377 *
1378 * Function l2c_fcr_get_next_xmit_sdu_seg
1379 *
1380 * Description Get the next SDU segment to transmit.
1381 *
1382 * Returns pointer to buffer with segment or NULL
1383 *
1384 ******************************************************************************/
l2c_fcr_get_next_xmit_sdu_seg(tL2C_CCB * p_ccb,uint16_t max_packet_length)1385 BT_HDR* l2c_fcr_get_next_xmit_sdu_seg(tL2C_CCB* p_ccb,
1386 uint16_t max_packet_length) {
1387 CHECK(p_ccb != NULL);
1388
1389 bool first_seg = false, /* The segment is the first part of data */
1390 mid_seg = false, /* The segment is the middle part of data */
1391 last_seg = false; /* The segment is the last part of data */
1392 uint16_t sdu_len = 0;
1393 BT_HDR *p_buf, *p_xmit;
1394 uint8_t* p;
1395 uint16_t max_pdu = p_ccb->tx_mps /* Needed? - L2CAP_MAX_HEADER_FCS*/;
1396
1397 /* If there is anything in the retransmit queue, that goes first
1398 */
1399 p_buf = (BT_HDR*)fixed_queue_try_dequeue(p_ccb->fcrb.retrans_q);
1400 if (p_buf != NULL) {
1401 /* Update Rx Seq and FCS if we acked some packets while this one was queued
1402 */
1403 prepare_I_frame(p_ccb, p_buf, true);
1404
1405 p_buf->event = p_ccb->local_cid;
1406
1407 return (p_buf);
1408 }
1409
1410 /* For BD/EDR controller, max_packet_length is set to 0 */
1411 /* For AMP controller, max_packet_length is set by available blocks */
1412 if ((max_packet_length > L2CAP_MAX_HEADER_FCS) &&
1413 (max_pdu + L2CAP_MAX_HEADER_FCS > max_packet_length)) {
1414 max_pdu = max_packet_length - L2CAP_MAX_HEADER_FCS;
1415 }
1416
1417 p_buf = (BT_HDR*)fixed_queue_try_peek_first(p_ccb->xmit_hold_q);
1418
1419 /* If there is more data than the MPS, it requires segmentation */
1420 if (p_buf->len > max_pdu) {
1421 /* We are using the "event" field to tell is if we already started
1422 * segmentation */
1423 if (p_buf->event == 0) {
1424 first_seg = true;
1425 sdu_len = p_buf->len;
1426 } else
1427 mid_seg = true;
1428
1429 /* Get a new buffer and copy the data that can be sent in a PDU */
1430 p_xmit = l2c_fcr_clone_buf(p_buf, L2CAP_MIN_OFFSET + L2CAP_SDU_LEN_OFFSET,
1431 max_pdu);
1432
1433 if (p_xmit != NULL) {
1434 p_buf->event = p_ccb->local_cid;
1435 p_xmit->event = p_ccb->local_cid;
1436
1437 p_buf->len -= max_pdu;
1438 p_buf->offset += max_pdu;
1439
1440 /* copy PBF setting */
1441 p_xmit->layer_specific = p_buf->layer_specific;
1442 } else /* Should never happen if the application has configured buffers
1443 correctly */
1444 {
1445 L2CAP_TRACE_ERROR(
1446 "L2CAP - cannot get buffer for segmentation, max_pdu: %u", max_pdu);
1447 return (NULL);
1448 }
1449 } else /* Use the original buffer if no segmentation, or the last segment */
1450 {
1451 p_xmit = (BT_HDR*)fixed_queue_try_dequeue(p_ccb->xmit_hold_q);
1452
1453 if (p_xmit->event != 0) last_seg = true;
1454
1455 p_xmit->event = p_ccb->local_cid;
1456 }
1457
1458 /* Step back to add the L2CAP headers */
1459 p_xmit->offset -= (L2CAP_PKT_OVERHEAD + L2CAP_FCR_OVERHEAD);
1460 p_xmit->len += L2CAP_PKT_OVERHEAD + L2CAP_FCR_OVERHEAD;
1461
1462 if (first_seg) {
1463 p_xmit->offset -= L2CAP_SDU_LEN_OVERHEAD;
1464 p_xmit->len += L2CAP_SDU_LEN_OVERHEAD;
1465 }
1466
1467 /* Set the pointer to the beginning of the data */
1468 p = (uint8_t*)(p_xmit + 1) + p_xmit->offset;
1469
1470 /* Now the L2CAP header */
1471
1472 /* Note: if FCS has to be included then the length is recalculated later */
1473 UINT16_TO_STREAM(p, p_xmit->len - L2CAP_PKT_OVERHEAD);
1474
1475 UINT16_TO_STREAM(p, p_ccb->remote_cid);
1476
1477 if (first_seg) {
1478 /* Skip control word and add SDU length */
1479 p += 2;
1480 UINT16_TO_STREAM(p, sdu_len);
1481
1482 /* We will store the SAR type in layer-specific */
1483 /* layer_specific is shared with flushable flag(bits 0-1), don't clear it */
1484 p_xmit->layer_specific |= L2CAP_FCR_START_SDU;
1485
1486 first_seg = false;
1487 } else if (mid_seg)
1488 p_xmit->layer_specific |= L2CAP_FCR_CONT_SDU;
1489 else if (last_seg)
1490 p_xmit->layer_specific |= L2CAP_FCR_END_SDU;
1491 else
1492 p_xmit->layer_specific |= L2CAP_FCR_UNSEG_SDU;
1493
1494 prepare_I_frame(p_ccb, p_xmit, false);
1495
1496 if (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE) {
1497 BT_HDR* p_wack =
1498 l2c_fcr_clone_buf(p_xmit, HCI_DATA_PREAMBLE_SIZE, p_xmit->len);
1499
1500 if (!p_wack) {
1501 L2CAP_TRACE_ERROR(
1502 "L2CAP - no buffer for xmit cloning, CID: 0x%04x Length: %u",
1503 p_ccb->local_cid, p_xmit->len);
1504
1505 /* We will not save the FCS in case we reconfigure and change options */
1506 p_xmit->len -= L2CAP_FCS_LEN;
1507
1508 /* Pretend we sent it and it got lost */
1509 fixed_queue_enqueue(p_ccb->fcrb.waiting_for_ack_q, p_xmit);
1510 return (NULL);
1511 } else {
1512 /* We will not save the FCS in case we reconfigure and change options */
1513 p_wack->len -= L2CAP_FCS_LEN;
1514
1515 p_wack->layer_specific = p_xmit->layer_specific;
1516 fixed_queue_enqueue(p_ccb->fcrb.waiting_for_ack_q, p_wack);
1517 }
1518
1519 }
1520
1521 return (p_xmit);
1522 }
1523
1524 /** Get the next PDU to transmit for LE connection oriented channel. Returns
1525 * pointer to buffer with PDU. |last_piece_of_sdu| will be set to true, if
1526 * returned PDU is last piece from this SDU.*/
l2c_lcc_get_next_xmit_sdu_seg(tL2C_CCB * p_ccb,bool * last_piece_of_sdu)1527 BT_HDR* l2c_lcc_get_next_xmit_sdu_seg(tL2C_CCB* p_ccb,
1528 bool* last_piece_of_sdu) {
1529 uint16_t max_pdu = p_ccb->peer_conn_cfg.mps - 4 /* Length and CID */;
1530
1531 BT_HDR* p_buf = (BT_HDR*)fixed_queue_try_peek_first(p_ccb->xmit_hold_q);
1532 bool first_pdu = (p_buf->event == 0) ? true : false;
1533
1534 uint16_t no_of_bytes_to_send = std::min(
1535 p_buf->len,
1536 (uint16_t)(first_pdu ? (max_pdu - L2CAP_LCC_SDU_LENGTH) : max_pdu));
1537 bool last_pdu = (no_of_bytes_to_send == p_buf->len);
1538
1539 /* Get a new buffer and copy the data that can be sent in a PDU */
1540 BT_HDR* p_xmit =
1541 l2c_fcr_clone_buf(p_buf, first_pdu ? L2CAP_LCC_OFFSET : L2CAP_MIN_OFFSET,
1542 no_of_bytes_to_send);
1543
1544 p_buf->event = p_ccb->local_cid;
1545 p_xmit->event = p_ccb->local_cid;
1546
1547 if (first_pdu) {
1548 p_xmit->offset -= L2CAP_LCC_SDU_LENGTH; /* for writing the SDU length. */
1549 uint8_t* p = (uint8_t*)(p_xmit + 1) + p_xmit->offset;
1550 UINT16_TO_STREAM(p, p_buf->len);
1551 p_xmit->len += L2CAP_LCC_SDU_LENGTH;
1552 }
1553
1554 p_buf->len -= no_of_bytes_to_send;
1555 p_buf->offset += no_of_bytes_to_send;
1556
1557 /* copy PBF setting */
1558 p_xmit->layer_specific = p_buf->layer_specific;
1559
1560 if (last_piece_of_sdu) *last_piece_of_sdu = last_pdu;
1561
1562 if (last_pdu) {
1563 p_buf = (BT_HDR*)fixed_queue_try_dequeue(p_ccb->xmit_hold_q);
1564 osi_free(p_buf);
1565 }
1566
1567 /* Step back to add the L2CAP headers */
1568 p_xmit->offset -= L2CAP_PKT_OVERHEAD;
1569 p_xmit->len += L2CAP_PKT_OVERHEAD;
1570
1571 /* Set the pointer to the beginning of the data */
1572 uint8_t* p = (uint8_t*)(p_xmit + 1) + p_xmit->offset;
1573
1574 /* Note: if FCS has to be included then the length is recalculated later */
1575 UINT16_TO_STREAM(p, p_xmit->len - L2CAP_PKT_OVERHEAD);
1576 UINT16_TO_STREAM(p, p_ccb->remote_cid);
1577 return (p_xmit);
1578 }
1579
1580 /*******************************************************************************
1581 * Configuration negotiation functions
1582 *
1583 * The following functions are used in negotiating channel modes during
1584 * configuration
1585 ******************************************************************************/
1586
1587 /*******************************************************************************
1588 *
1589 * Function l2c_fcr_chk_chan_modes
1590 *
1591 * Description Validates and adjusts if necessary, the FCR options
1592 * based on remote EXT features.
1593 *
1594 * Note: This assumes peer EXT Features have been received.
1595 * Basic mode is used if FCR Options have not been received
1596 *
1597 * Returns uint8_t - nonzero if can continue, '0' if no compatible
1598 * channels
1599 *
1600 ******************************************************************************/
l2c_fcr_chk_chan_modes(tL2C_CCB * p_ccb)1601 uint8_t l2c_fcr_chk_chan_modes(tL2C_CCB* p_ccb) {
1602 CHECK(p_ccb != NULL);
1603
1604 /* Remove nonbasic options that the peer does not support */
1605 if (!(p_ccb->p_lcb->peer_ext_fea & L2CAP_EXTFEA_ENH_RETRANS) &&
1606 p_ccb->p_rcb->ertm_info.preferred_mode == L2CAP_FCR_ERTM_MODE) {
1607 L2CAP_TRACE_WARNING(
1608 "L2CAP - Peer does not support our desired channel types");
1609 p_ccb->p_rcb->ertm_info.preferred_mode = 0;
1610 return false;
1611 }
1612 return true;
1613 }
1614
1615 /*******************************************************************************
1616 *
1617 * Function l2c_fcr_adj_monitor_retran_timeout
1618 *
1619 * Description Overrides monitor/retrans timer value based on controller
1620 *
1621 * Returns None
1622 *
1623 ******************************************************************************/
l2c_fcr_adj_monitor_retran_timeout(tL2C_CCB * p_ccb)1624 void l2c_fcr_adj_monitor_retran_timeout(tL2C_CCB* p_ccb) {
1625 CHECK(p_ccb != NULL);
1626
1627 /* adjust our monitor/retran timeout */
1628 if (p_ccb->out_cfg_fcr_present) {
1629 /*
1630 ** if we requestd ERTM or accepted ERTM
1631 ** We may accept ERTM even if we didn't request ERTM, in case of requesting
1632 *STREAM
1633 */
1634 if ((p_ccb->our_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE) ||
1635 (p_ccb->peer_cfg.fcr.mode == L2CAP_FCR_ERTM_MODE)) {
1636 /* upper layer setting is ignored */
1637 p_ccb->our_cfg.fcr.mon_tout = L2CAP_MIN_MONITOR_TOUT;
1638 p_ccb->our_cfg.fcr.rtrans_tout = L2CAP_MIN_RETRANS_TOUT;
1639 } else {
1640 p_ccb->our_cfg.fcr.mon_tout = 0;
1641 p_ccb->our_cfg.fcr.rtrans_tout = 0;
1642 }
1643
1644 L2CAP_TRACE_DEBUG(
1645 "l2c_fcr_adj_monitor_retran_timeout: mon_tout:%d, rtrans_tout:%d",
1646 p_ccb->our_cfg.fcr.mon_tout, p_ccb->our_cfg.fcr.rtrans_tout);
1647 }
1648 }
1649 /*******************************************************************************
1650 *
1651 * Function l2c_fcr_adj_our_rsp_options
1652 *
1653 * Description Overrides any neccesary FCR options passed in from
1654 * L2CA_ConfigRsp based on our FCR options.
1655 * Only makes adjustments if channel is in ERTM mode.
1656 *
1657 * Returns None
1658 *
1659 ******************************************************************************/
l2c_fcr_adj_our_rsp_options(tL2C_CCB * p_ccb,tL2CAP_CFG_INFO * p_cfg)1660 void l2c_fcr_adj_our_rsp_options(tL2C_CCB* p_ccb, tL2CAP_CFG_INFO* p_cfg) {
1661 CHECK(p_ccb != NULL);
1662 CHECK(p_cfg != NULL);
1663
1664 /* adjust our monitor/retran timeout */
1665 l2c_fcr_adj_monitor_retran_timeout(p_ccb);
1666
1667 p_cfg->fcr_present = p_ccb->out_cfg_fcr_present;
1668
1669 if (p_cfg->fcr_present) {
1670 /* Temporary - until a better algorithm is implemented */
1671 /* If peer's tx_wnd_sz requires too many buffers for us to support, then
1672 * adjust it. For now, respond with our own tx_wnd_sz. */
1673 /* Note: peer is not guaranteed to obey our adjustment */
1674 if (p_ccb->peer_cfg.fcr.tx_win_sz > p_ccb->our_cfg.fcr.tx_win_sz) {
1675 L2CAP_TRACE_DEBUG("%s: adjusting requested tx_win_sz from %i to %i",
1676 __func__, p_ccb->peer_cfg.fcr.tx_win_sz,
1677 p_ccb->our_cfg.fcr.tx_win_sz);
1678 p_ccb->peer_cfg.fcr.tx_win_sz = p_ccb->our_cfg.fcr.tx_win_sz;
1679 }
1680
1681 p_cfg->fcr.mode = p_ccb->peer_cfg.fcr.mode;
1682 p_cfg->fcr.tx_win_sz = p_ccb->peer_cfg.fcr.tx_win_sz;
1683 p_cfg->fcr.max_transmit = p_ccb->peer_cfg.fcr.max_transmit;
1684 p_cfg->fcr.mps = p_ccb->peer_cfg.fcr.mps;
1685 p_cfg->fcr.rtrans_tout = p_ccb->our_cfg.fcr.rtrans_tout;
1686 p_cfg->fcr.mon_tout = p_ccb->our_cfg.fcr.mon_tout;
1687 }
1688 }
1689
1690 /*******************************************************************************
1691 *
1692 * Function l2c_fcr_renegotiate_chan
1693 *
1694 * Description Called upon unsuccessful peer response to config request.
1695 * If the error is because of the channel mode, it will try
1696 * to resend using another supported optional channel.
1697 *
1698 * Returns true if resent configuration, False if channel matches or
1699 * cannot match.
1700 *
1701 ******************************************************************************/
l2c_fcr_renegotiate_chan(tL2C_CCB * p_ccb,tL2CAP_CFG_INFO * p_cfg)1702 bool l2c_fcr_renegotiate_chan(tL2C_CCB* p_ccb, tL2CAP_CFG_INFO* p_cfg) {
1703 CHECK(p_ccb != NULL);
1704 CHECK(p_cfg != NULL);
1705
1706 uint8_t peer_mode = p_ccb->our_cfg.fcr.mode;
1707 bool can_renegotiate;
1708
1709 /* Skip if this is a reconfiguration from OPEN STATE or if FCR is not returned
1710 */
1711 if (!p_cfg->fcr_present || (p_ccb->config_done & RECONFIG_FLAG))
1712 return (false);
1713
1714 /* Only retry if there are more channel options to try */
1715 if (p_cfg->result == L2CAP_CFG_UNACCEPTABLE_PARAMS) {
1716 peer_mode = (p_cfg->fcr_present) ? p_cfg->fcr.mode : L2CAP_FCR_BASIC_MODE;
1717
1718 if (p_ccb->our_cfg.fcr.mode != peer_mode) {
1719 if ((--p_ccb->fcr_cfg_tries) == 0) {
1720 p_cfg->result = L2CAP_CFG_FAILED_NO_REASON;
1721 L2CAP_TRACE_WARNING("l2c_fcr_renegotiate_chan (Max retries exceeded)");
1722 }
1723
1724 can_renegotiate = false;
1725
1726 /* Try another supported mode if available based on our last attempted
1727 * channel */
1728 switch (p_ccb->our_cfg.fcr.mode) {
1729 case L2CAP_FCR_ERTM_MODE:
1730 /* We can try basic for any other peer mode because it's always
1731 * supported */
1732 L2CAP_TRACE_DEBUG("%s(Trying Basic)", __func__);
1733 can_renegotiate = true;
1734 p_ccb->our_cfg.fcr.mode = L2CAP_FCR_BASIC_MODE;
1735 break;
1736
1737 default:
1738 /* All other scenarios cannot be renegotiated */
1739 break;
1740 }
1741
1742 if (can_renegotiate) {
1743 p_ccb->our_cfg.fcr_present = true;
1744
1745 if (p_ccb->our_cfg.fcr.mode == L2CAP_FCR_BASIC_MODE) {
1746 p_ccb->our_cfg.fcs_present = false;
1747 p_ccb->our_cfg.ext_flow_spec_present = false;
1748
1749 /* Basic Mode uses ACL Data Pool, make sure the MTU fits */
1750 if ((p_cfg->mtu_present) && (p_cfg->mtu > L2CAP_MTU_SIZE)) {
1751 L2CAP_TRACE_WARNING("L2CAP - adjust MTU: %u too large", p_cfg->mtu);
1752 p_cfg->mtu = L2CAP_MTU_SIZE;
1753 }
1754 }
1755
1756 l2cu_process_our_cfg_req(p_ccb, &p_ccb->our_cfg);
1757 l2cu_send_peer_config_req(p_ccb, &p_ccb->our_cfg);
1758 alarm_set_on_mloop(p_ccb->l2c_ccb_timer, L2CAP_CHNL_CFG_TIMEOUT_MS,
1759 l2c_ccb_timer_timeout, p_ccb);
1760 return (true);
1761 }
1762 }
1763 }
1764
1765 /* Disconnect if the channels do not match */
1766 if (p_ccb->our_cfg.fcr.mode != peer_mode) {
1767 L2CAP_TRACE_WARNING("L2C CFG: Channels incompatible (local %d, peer %d)",
1768 p_ccb->our_cfg.fcr.mode, peer_mode);
1769 l2cu_disconnect_chnl(p_ccb);
1770 }
1771
1772 return (false);
1773 }
1774
1775 /*******************************************************************************
1776 *
1777 * Function l2c_fcr_process_peer_cfg_req
1778 *
1779 * Description This function is called to process the FCR options passed
1780 * in the peer's configuration request.
1781 *
1782 * Returns uint8_t - L2CAP_PEER_CFG_OK, L2CAP_PEER_CFG_UNACCEPTABLE,
1783 * or L2CAP_PEER_CFG_DISCONNECT.
1784 *
1785 ******************************************************************************/
l2c_fcr_process_peer_cfg_req(tL2C_CCB * p_ccb,tL2CAP_CFG_INFO * p_cfg)1786 uint8_t l2c_fcr_process_peer_cfg_req(tL2C_CCB* p_ccb, tL2CAP_CFG_INFO* p_cfg) {
1787 CHECK(p_ccb != NULL);
1788 CHECK(p_cfg != NULL);
1789
1790 uint16_t max_retrans_size;
1791 uint8_t fcr_ok = L2CAP_PEER_CFG_OK;
1792
1793 p_ccb->p_lcb->w4_info_rsp =
1794 false; /* Handles T61x SonyEricsson Bug in Info Request */
1795
1796 L2CAP_TRACE_EVENT(
1797 "l2c_fcr_process_peer_cfg_req() CFG fcr_present:%d fcr.mode:%d CCB FCR "
1798 "mode:%d preferred: %u",
1799 p_cfg->fcr_present, p_cfg->fcr.mode, p_ccb->our_cfg.fcr.mode,
1800 p_ccb->p_rcb->ertm_info.preferred_mode);
1801
1802 /* Need to negotiate if our modes are not the same */
1803 if (p_cfg->fcr.mode != p_ccb->p_rcb->ertm_info.preferred_mode) {
1804 /* If peer wants a mode that we don't support then retry our mode (ex.
1805 *rtx/flc), OR
1806 ** If we want ERTM and they want non-basic mode, retry our mode.
1807 ** Note: If we have already determined they support our mode previously
1808 ** from their EXF mask.
1809 */
1810 if ((((1 << p_cfg->fcr.mode) & L2CAP_FCR_CHAN_OPT_ALL_MASK) == 0) ||
1811 ((p_ccb->p_rcb->ertm_info.preferred_mode == L2CAP_FCR_ERTM_MODE) &&
1812 (p_cfg->fcr.mode != L2CAP_FCR_BASIC_MODE))) {
1813 p_cfg->fcr.mode = p_ccb->our_cfg.fcr.mode;
1814 p_cfg->fcr.tx_win_sz = p_ccb->our_cfg.fcr.tx_win_sz;
1815 p_cfg->fcr.max_transmit = p_ccb->our_cfg.fcr.max_transmit;
1816 fcr_ok = L2CAP_PEER_CFG_UNACCEPTABLE;
1817 }
1818
1819 /* If we wanted basic, then try to renegotiate it */
1820 else if (p_ccb->p_rcb->ertm_info.preferred_mode == L2CAP_FCR_BASIC_MODE) {
1821 p_cfg->fcr.mode = L2CAP_FCR_BASIC_MODE;
1822 p_cfg->fcr.max_transmit = p_cfg->fcr.tx_win_sz = 0;
1823 p_cfg->fcr.rtrans_tout = p_cfg->fcr.mon_tout = p_cfg->fcr.mps = 0;
1824 p_ccb->our_cfg.fcr.rtrans_tout = p_ccb->our_cfg.fcr.mon_tout =
1825 p_ccb->our_cfg.fcr.mps = 0;
1826 fcr_ok = L2CAP_PEER_CFG_UNACCEPTABLE;
1827 }
1828 }
1829
1830 /* Configuration for FCR channels so make any adjustments and fwd to upper
1831 * layer */
1832 if (fcr_ok == L2CAP_PEER_CFG_OK) {
1833 /* by default don't need to send params in the response */
1834 p_ccb->out_cfg_fcr_present = false;
1835
1836 /* Make any needed adjustments for the response to the peer */
1837 if (p_cfg->fcr_present && p_cfg->fcr.mode != L2CAP_FCR_BASIC_MODE) {
1838 /* Peer desires to bypass FCS check, and streaming or ERTM mode */
1839 if (p_cfg->fcs_present) {
1840 p_ccb->peer_cfg.fcs = p_cfg->fcs;
1841 }
1842
1843 max_retrans_size = BT_DEFAULT_BUFFER_SIZE - sizeof(BT_HDR) -
1844 L2CAP_MIN_OFFSET - L2CAP_SDU_LEN_OFFSET -
1845 L2CAP_FCS_LEN;
1846
1847 /* Ensure the MPS is not bigger than the MTU */
1848 if ((p_cfg->fcr.mps == 0) || (p_cfg->fcr.mps > p_ccb->peer_cfg.mtu)) {
1849 p_cfg->fcr.mps = p_ccb->peer_cfg.mtu;
1850 p_ccb->out_cfg_fcr_present = true;
1851 }
1852
1853 /* Ensure the MPS is not bigger than our retransmission buffer */
1854 if (p_cfg->fcr.mps > max_retrans_size) {
1855 L2CAP_TRACE_DEBUG("CFG: Overriding MPS to %d (orig %d)",
1856 max_retrans_size, p_cfg->fcr.mps);
1857
1858 p_cfg->fcr.mps = max_retrans_size;
1859 p_ccb->out_cfg_fcr_present = true;
1860 }
1861
1862 if (p_cfg->fcr.mode == L2CAP_FCR_ERTM_MODE) {
1863 /* Always respond with FCR ERTM parameters */
1864 p_ccb->out_cfg_fcr_present = true;
1865 }
1866 }
1867
1868 /* Everything ok, so save the peer's adjusted fcr options */
1869 p_ccb->peer_cfg.fcr = p_cfg->fcr;
1870
1871 } else if (fcr_ok == L2CAP_PEER_CFG_UNACCEPTABLE) {
1872 /* Allow peer only one retry for mode */
1873 if (p_ccb->peer_cfg_already_rejected)
1874 fcr_ok = L2CAP_PEER_CFG_DISCONNECT;
1875 else
1876 p_ccb->peer_cfg_already_rejected = true;
1877 }
1878
1879 return (fcr_ok);
1880 }
1881