1 /* 2 * net/dccp/ackvec.c 3 * 4 * An implementation of the DCCP protocol 5 * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net> 6 * 7 * This program is free software; you can redistribute it and/or modify it 8 * under the terms of the GNU General Public License as published by the 9 * Free Software Foundation; version 2 of the License; 10 */ 11 12 #include "ackvec.h" 13 #include "dccp.h" 14 15 #include <linux/dccp.h> 16 #include <linux/init.h> 17 #include <linux/errno.h> 18 #include <linux/kernel.h> 19 #include <linux/skbuff.h> 20 #include <linux/slab.h> 21 22 #include <net/sock.h> 23 24 static struct kmem_cache *dccp_ackvec_slab; 25 static struct kmem_cache *dccp_ackvec_record_slab; 26 27 static struct dccp_ackvec_record *dccp_ackvec_record_new(void) 28 { 29 struct dccp_ackvec_record *avr = 30 kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC); 31 32 if (avr != NULL) 33 INIT_LIST_HEAD(&avr->dccpavr_node); 34 35 return avr; 36 } 37 38 static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr) 39 { 40 if (unlikely(avr == NULL)) 41 return; 42 /* Check if deleting a linked record */ 43 WARN_ON(!list_empty(&avr->dccpavr_node)); 44 kmem_cache_free(dccp_ackvec_record_slab, avr); 45 } 46 47 static void dccp_ackvec_insert_avr(struct dccp_ackvec *av, 48 struct dccp_ackvec_record *avr) 49 { 50 /* 51 * AVRs are sorted by seqno. Since we are sending them in order, we 52 * just add the AVR at the head of the list. 53 * -sorbo. 54 */ 55 if (!list_empty(&av->dccpav_records)) { 56 const struct dccp_ackvec_record *head = 57 list_entry(av->dccpav_records.next, 58 struct dccp_ackvec_record, 59 dccpavr_node); 60 BUG_ON(before48(avr->dccpavr_ack_seqno, 61 head->dccpavr_ack_seqno)); 62 } 63 64 list_add(&avr->dccpavr_node, &av->dccpav_records); 65 } 66 67 int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) 68 { 69 struct dccp_sock *dp = dccp_sk(sk); 70 struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec; 71 /* Figure out how many options do we need to represent the ackvec */ 72 const u16 nr_opts = (av->dccpav_vec_len + 73 DCCP_MAX_ACKVEC_OPT_LEN - 1) / 74 DCCP_MAX_ACKVEC_OPT_LEN; 75 u16 len = av->dccpav_vec_len + 2 * nr_opts, i; 76 struct timeval now; 77 u32 elapsed_time; 78 const unsigned char *tail, *from; 79 unsigned char *to; 80 struct dccp_ackvec_record *avr; 81 82 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 83 return -1; 84 85 dccp_timestamp(sk, &now); 86 elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10; 87 88 if (elapsed_time != 0 && 89 dccp_insert_option_elapsed_time(sk, skb, elapsed_time)) 90 return -1; 91 92 avr = dccp_ackvec_record_new(); 93 if (avr == NULL) 94 return -1; 95 96 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 97 98 to = skb_push(skb, len); 99 len = av->dccpav_vec_len; 100 from = av->dccpav_buf + av->dccpav_buf_head; 101 tail = av->dccpav_buf + DCCP_MAX_ACKVEC_LEN; 102 103 for (i = 0; i < nr_opts; ++i) { 104 int copylen = len; 105 106 if (len > DCCP_MAX_ACKVEC_OPT_LEN) 107 copylen = DCCP_MAX_ACKVEC_OPT_LEN; 108 109 *to++ = DCCPO_ACK_VECTOR_0; 110 *to++ = copylen + 2; 111 112 /* Check if buf_head wraps */ 113 if (from + copylen > tail) { 114 const u16 tailsize = tail - from; 115 116 memcpy(to, from, tailsize); 117 to += tailsize; 118 len -= tailsize; 119 copylen -= tailsize; 120 from = av->dccpav_buf; 121 } 122 123 memcpy(to, from, copylen); 124 from += copylen; 125 to += copylen; 126 len -= copylen; 127 } 128 129 /* 130 * From RFC 4340, A.2: 131 * 132 * For each acknowledgement it sends, the HC-Receiver will add an 133 * acknowledgement record. ack_seqno will equal the HC-Receiver 134 * sequence number it used for the ack packet; ack_ptr will equal 135 * buf_head; ack_ackno will equal buf_ackno; and ack_nonce will 136 * equal buf_nonce. 137 */ 138 avr->dccpavr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq; 139 avr->dccpavr_ack_ptr = av->dccpav_buf_head; 140 avr->dccpavr_ack_ackno = av->dccpav_buf_ackno; 141 avr->dccpavr_ack_nonce = av->dccpav_buf_nonce; 142 avr->dccpavr_sent_len = av->dccpav_vec_len; 143 144 dccp_ackvec_insert_avr(av, avr); 145 146 dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, " 147 "ack_ackno=%llu\n", 148 dccp_role(sk), avr->dccpavr_sent_len, 149 (unsigned long long)avr->dccpavr_ack_seqno, 150 (unsigned long long)avr->dccpavr_ack_ackno); 151 return 0; 152 } 153 154 struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority) 155 { 156 struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority); 157 158 if (av != NULL) { 159 av->dccpav_buf_head = DCCP_MAX_ACKVEC_LEN - 1; 160 av->dccpav_buf_ackno = UINT48_MAX + 1; 161 av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0; 162 av->dccpav_time.tv_sec = 0; 163 av->dccpav_time.tv_usec = 0; 164 av->dccpav_vec_len = 0; 165 INIT_LIST_HEAD(&av->dccpav_records); 166 } 167 168 return av; 169 } 170 171 void dccp_ackvec_free(struct dccp_ackvec *av) 172 { 173 if (unlikely(av == NULL)) 174 return; 175 176 if (!list_empty(&av->dccpav_records)) { 177 struct dccp_ackvec_record *avr, *next; 178 179 list_for_each_entry_safe(avr, next, &av->dccpav_records, 180 dccpavr_node) { 181 list_del_init(&avr->dccpavr_node); 182 dccp_ackvec_record_delete(avr); 183 } 184 } 185 186 kmem_cache_free(dccp_ackvec_slab, av); 187 } 188 189 static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av, 190 const u32 index) 191 { 192 return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK; 193 } 194 195 static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av, 196 const u32 index) 197 { 198 return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK; 199 } 200 201 /* 202 * If several packets are missing, the HC-Receiver may prefer to enter multiple 203 * bytes with run length 0, rather than a single byte with a larger run length; 204 * this simplifies table updates if one of the missing packets arrives. 205 */ 206 static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av, 207 const unsigned int packets, 208 const unsigned char state) 209 { 210 unsigned int gap; 211 long new_head; 212 213 if (av->dccpav_vec_len + packets > DCCP_MAX_ACKVEC_LEN) 214 return -ENOBUFS; 215 216 gap = packets - 1; 217 new_head = av->dccpav_buf_head - packets; 218 219 if (new_head < 0) { 220 if (gap > 0) { 221 memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED, 222 gap + new_head + 1); 223 gap = -new_head; 224 } 225 new_head += DCCP_MAX_ACKVEC_LEN; 226 } 227 228 av->dccpav_buf_head = new_head; 229 230 if (gap > 0) 231 memset(av->dccpav_buf + av->dccpav_buf_head + 1, 232 DCCP_ACKVEC_STATE_NOT_RECEIVED, gap); 233 234 av->dccpav_buf[av->dccpav_buf_head] = state; 235 av->dccpav_vec_len += packets; 236 return 0; 237 } 238 239 /* 240 * Implements the RFC 4340, Appendix A 241 */ 242 int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk, 243 const u64 ackno, const u8 state) 244 { 245 /* 246 * Check at the right places if the buffer is full, if it is, tell the 247 * caller to start dropping packets till the HC-Sender acks our ACK 248 * vectors, when we will free up space in dccpav_buf. 249 * 250 * We may well decide to do buffer compression, etc, but for now lets 251 * just drop. 252 * 253 * From Appendix A.1.1 (`New Packets'): 254 * 255 * Of course, the circular buffer may overflow, either when the 256 * HC-Sender is sending data at a very high rate, when the 257 * HC-Receiver's acknowledgements are not reaching the HC-Sender, 258 * or when the HC-Sender is forgetting to acknowledge those acks 259 * (so the HC-Receiver is unable to clean up old state). In this 260 * case, the HC-Receiver should either compress the buffer (by 261 * increasing run lengths when possible), transfer its state to 262 * a larger buffer, or, as a last resort, drop all received 263 * packets, without processing them whatsoever, until its buffer 264 * shrinks again. 265 */ 266 267 /* See if this is the first ackno being inserted */ 268 if (av->dccpav_vec_len == 0) { 269 av->dccpav_buf[av->dccpav_buf_head] = state; 270 av->dccpav_vec_len = 1; 271 } else if (after48(ackno, av->dccpav_buf_ackno)) { 272 const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno, 273 ackno); 274 275 /* 276 * Look if the state of this packet is the same as the 277 * previous ackno and if so if we can bump the head len. 278 */ 279 if (delta == 1 && 280 dccp_ackvec_state(av, av->dccpav_buf_head) == state && 281 (dccp_ackvec_len(av, av->dccpav_buf_head) < 282 DCCP_ACKVEC_LEN_MASK)) 283 av->dccpav_buf[av->dccpav_buf_head]++; 284 else if (dccp_ackvec_set_buf_head_state(av, delta, state)) 285 return -ENOBUFS; 286 } else { 287 /* 288 * A.1.2. Old Packets 289 * 290 * When a packet with Sequence Number S <= buf_ackno 291 * arrives, the HC-Receiver will scan the table for 292 * the byte corresponding to S. (Indexing structures 293 * could reduce the complexity of this scan.) 294 */ 295 u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno); 296 u32 index = av->dccpav_buf_head; 297 298 while (1) { 299 const u8 len = dccp_ackvec_len(av, index); 300 const u8 state = dccp_ackvec_state(av, index); 301 /* 302 * valid packets not yet in dccpav_buf have a reserved 303 * entry, with a len equal to 0. 304 */ 305 if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED && 306 len == 0 && delta == 0) { /* Found our 307 reserved seat! */ 308 dccp_pr_debug("Found %llu reserved seat!\n", 309 (unsigned long long)ackno); 310 av->dccpav_buf[index] = state; 311 goto out; 312 } 313 /* len == 0 means one packet */ 314 if (delta < len + 1) 315 goto out_duplicate; 316 317 delta -= len + 1; 318 if (++index == DCCP_MAX_ACKVEC_LEN) 319 index = 0; 320 } 321 } 322 323 av->dccpav_buf_ackno = ackno; 324 dccp_timestamp(sk, &av->dccpav_time); 325 out: 326 return 0; 327 328 out_duplicate: 329 /* Duplicate packet */ 330 dccp_pr_debug("Received a dup or already considered lost " 331 "packet: %llu\n", (unsigned long long)ackno); 332 return -EILSEQ; 333 } 334 335 #ifdef CONFIG_IP_DCCP_DEBUG 336 void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len) 337 { 338 dccp_pr_debug_cat("ACK vector len=%d, ackno=%llu |", len, 339 (unsigned long long)ackno); 340 341 while (len--) { 342 const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6; 343 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK; 344 345 dccp_pr_debug_cat("%d,%d|", state, rl); 346 ++vector; 347 } 348 349 dccp_pr_debug_cat("\n"); 350 } 351 352 void dccp_ackvec_print(const struct dccp_ackvec *av) 353 { 354 dccp_ackvector_print(av->dccpav_buf_ackno, 355 av->dccpav_buf + av->dccpav_buf_head, 356 av->dccpav_vec_len); 357 } 358 #endif 359 360 static void dccp_ackvec_throw_record(struct dccp_ackvec *av, 361 struct dccp_ackvec_record *avr) 362 { 363 struct dccp_ackvec_record *next; 364 365 /* sort out vector length */ 366 if (av->dccpav_buf_head <= avr->dccpavr_ack_ptr) 367 av->dccpav_vec_len = avr->dccpavr_ack_ptr - av->dccpav_buf_head; 368 else 369 av->dccpav_vec_len = DCCP_MAX_ACKVEC_LEN - 1 370 - av->dccpav_buf_head 371 + avr->dccpavr_ack_ptr; 372 373 /* free records */ 374 list_for_each_entry_safe_from(avr, next, &av->dccpav_records, 375 dccpavr_node) { 376 list_del_init(&avr->dccpavr_node); 377 dccp_ackvec_record_delete(avr); 378 } 379 } 380 381 void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk, 382 const u64 ackno) 383 { 384 struct dccp_ackvec_record *avr; 385 386 /* 387 * If we traverse backwards, it should be faster when we have large 388 * windows. We will be receiving ACKs for stuff we sent a while back 389 * -sorbo. 390 */ 391 list_for_each_entry_reverse(avr, &av->dccpav_records, dccpavr_node) { 392 if (ackno == avr->dccpavr_ack_seqno) { 393 dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, " 394 "ack_ackno=%llu, ACKED!\n", 395 dccp_role(sk), 1, 396 (unsigned long long)avr->dccpavr_ack_seqno, 397 (unsigned long long)avr->dccpavr_ack_ackno); 398 dccp_ackvec_throw_record(av, avr); 399 break; 400 } else if (avr->dccpavr_ack_seqno > ackno) 401 break; /* old news */ 402 } 403 } 404 405 static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av, 406 struct sock *sk, u64 *ackno, 407 const unsigned char len, 408 const unsigned char *vector) 409 { 410 unsigned char i; 411 struct dccp_ackvec_record *avr; 412 413 /* Check if we actually sent an ACK vector */ 414 if (list_empty(&av->dccpav_records)) 415 return; 416 417 i = len; 418 /* 419 * XXX 420 * I think it might be more efficient to work backwards. See comment on 421 * rcv_ackno. -sorbo. 422 */ 423 avr = list_entry(av->dccpav_records.next, struct dccp_ackvec_record, 424 dccpavr_node); 425 while (i--) { 426 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK; 427 u64 ackno_end_rl; 428 429 dccp_set_seqno(&ackno_end_rl, *ackno - rl); 430 431 /* 432 * If our AVR sequence number is greater than the ack, go 433 * forward in the AVR list until it is not so. 434 */ 435 list_for_each_entry_from(avr, &av->dccpav_records, 436 dccpavr_node) { 437 if (!after48(avr->dccpavr_ack_seqno, *ackno)) 438 goto found; 439 } 440 /* End of the dccpav_records list, not found, exit */ 441 break; 442 found: 443 if (between48(avr->dccpavr_ack_seqno, ackno_end_rl, *ackno)) { 444 const u8 state = *vector & DCCP_ACKVEC_STATE_MASK; 445 if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) { 446 dccp_pr_debug("%s ACK vector 0, len=%d, " 447 "ack_seqno=%llu, ack_ackno=%llu, " 448 "ACKED!\n", 449 dccp_role(sk), len, 450 (unsigned long long) 451 avr->dccpavr_ack_seqno, 452 (unsigned long long) 453 avr->dccpavr_ack_ackno); 454 dccp_ackvec_throw_record(av, avr); 455 break; 456 } 457 /* 458 * If it wasn't received, continue scanning... we might 459 * find another one. 460 */ 461 } 462 463 dccp_set_seqno(ackno, ackno_end_rl - 1); 464 ++vector; 465 } 466 } 467 468 int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb, 469 u64 *ackno, const u8 opt, const u8 *value, const u8 len) 470 { 471 if (len > DCCP_MAX_ACKVEC_OPT_LEN) 472 return -1; 473 474 /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */ 475 dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk, 476 ackno, len, value); 477 return 0; 478 } 479 480 int __init dccp_ackvec_init(void) 481 { 482 dccp_ackvec_slab = kmem_cache_create("dccp_ackvec", 483 sizeof(struct dccp_ackvec), 0, 484 SLAB_HWCACHE_ALIGN, NULL); 485 if (dccp_ackvec_slab == NULL) 486 goto out_err; 487 488 dccp_ackvec_record_slab = 489 kmem_cache_create("dccp_ackvec_record", 490 sizeof(struct dccp_ackvec_record), 491 0, SLAB_HWCACHE_ALIGN, NULL); 492 if (dccp_ackvec_record_slab == NULL) 493 goto out_destroy_slab; 494 495 return 0; 496 497 out_destroy_slab: 498 kmem_cache_destroy(dccp_ackvec_slab); 499 dccp_ackvec_slab = NULL; 500 out_err: 501 DCCP_CRIT("Unable to create Ack Vector slab cache"); 502 return -ENOBUFS; 503 } 504 505 void dccp_ackvec_exit(void) 506 { 507 if (dccp_ackvec_slab != NULL) { 508 kmem_cache_destroy(dccp_ackvec_slab); 509 dccp_ackvec_slab = NULL; 510 } 511 if (dccp_ackvec_record_slab != NULL) { 512 kmem_cache_destroy(dccp_ackvec_record_slab); 513 dccp_ackvec_record_slab = NULL; 514 } 515 } 516