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