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/skbuff.h> 17 18 #include <net/sock.h> 19 20 int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) 21 { 22 struct dccp_sock *dp = dccp_sk(sk); 23 struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec; 24 int len = av->dccpav_vec_len + 2; 25 struct timeval now; 26 u32 elapsed_time; 27 unsigned char *to, *from; 28 29 dccp_timestamp(sk, &now); 30 elapsed_time = timeval_delta(&now, &av->dccpav_time) / 10; 31 32 if (elapsed_time != 0) 33 dccp_insert_option_elapsed_time(sk, skb, elapsed_time); 34 35 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 36 return -1; 37 38 /* 39 * XXX: now we have just one ack vector sent record, so 40 * we have to wait for it to be cleared. 41 * 42 * Of course this is not acceptable, but this is just for 43 * basic testing now. 44 */ 45 if (av->dccpav_ack_seqno != DCCP_MAX_SEQNO + 1) 46 return -1; 47 48 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 49 50 to = skb_push(skb, len); 51 *to++ = DCCPO_ACK_VECTOR_0; 52 *to++ = len; 53 54 len = av->dccpav_vec_len; 55 from = av->dccpav_buf + av->dccpav_buf_head; 56 57 /* Check if buf_head wraps */ 58 if (av->dccpav_buf_head + len > av->dccpav_vec_len) { 59 const u32 tailsize = (av->dccpav_vec_len - av->dccpav_buf_head); 60 61 memcpy(to, from, tailsize); 62 to += tailsize; 63 len -= tailsize; 64 from = av->dccpav_buf; 65 } 66 67 memcpy(to, from, len); 68 /* 69 * From draft-ietf-dccp-spec-11.txt: 70 * 71 * For each acknowledgement it sends, the HC-Receiver will add an 72 * acknowledgement record. ack_seqno will equal the HC-Receiver 73 * sequence number it used for the ack packet; ack_ptr will equal 74 * buf_head; ack_ackno will equal buf_ackno; and ack_nonce will 75 * equal buf_nonce. 76 * 77 * This implemention uses just one ack record for now. 78 */ 79 av->dccpav_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq; 80 av->dccpav_ack_ptr = av->dccpav_buf_head; 81 av->dccpav_ack_ackno = av->dccpav_buf_ackno; 82 av->dccpav_ack_nonce = av->dccpav_buf_nonce; 83 av->dccpav_sent_len = av->dccpav_vec_len; 84 85 dccp_pr_debug("%sACK Vector 0, len=%d, ack_seqno=%llu, " 86 "ack_ackno=%llu\n", 87 debug_prefix, av->dccpav_sent_len, 88 (unsigned long long)av->dccpav_ack_seqno, 89 (unsigned long long)av->dccpav_ack_ackno); 90 return -1; 91 } 92 93 struct dccp_ackvec *dccp_ackvec_alloc(const unsigned int len, 94 const gfp_t priority) 95 { 96 struct dccp_ackvec *av = kmalloc(sizeof(*av) + len, priority); 97 98 if (av != NULL) { 99 av->dccpav_buf_len = len; 100 av->dccpav_buf_head = 101 av->dccpav_buf_tail = av->dccpav_buf_len - 1; 102 av->dccpav_buf_ackno = 103 av->dccpav_ack_ackno = av->dccpav_ack_seqno = ~0LLU; 104 av->dccpav_buf_nonce = av->dccpav_buf_nonce = 0; 105 av->dccpav_ack_ptr = 0; 106 av->dccpav_time.tv_sec = 0; 107 av->dccpav_time.tv_usec = 0; 108 av->dccpav_sent_len = av->dccpav_vec_len = 0; 109 } 110 111 return av; 112 } 113 114 void dccp_ackvec_free(struct dccp_ackvec *av) 115 { 116 kfree(av); 117 } 118 119 static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av, 120 const unsigned int index) 121 { 122 return av->dccpav_buf[index] & DCCP_ACKVEC_STATE_MASK; 123 } 124 125 static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av, 126 const unsigned int index) 127 { 128 return av->dccpav_buf[index] & DCCP_ACKVEC_LEN_MASK; 129 } 130 131 /* 132 * If several packets are missing, the HC-Receiver may prefer to enter multiple 133 * bytes with run length 0, rather than a single byte with a larger run length; 134 * this simplifies table updates if one of the missing packets arrives. 135 */ 136 static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av, 137 const unsigned int packets, 138 const unsigned char state) 139 { 140 unsigned int gap; 141 signed long new_head; 142 143 if (av->dccpav_vec_len + packets > av->dccpav_buf_len) 144 return -ENOBUFS; 145 146 gap = packets - 1; 147 new_head = av->dccpav_buf_head - packets; 148 149 if (new_head < 0) { 150 if (gap > 0) { 151 memset(av->dccpav_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED, 152 gap + new_head + 1); 153 gap = -new_head; 154 } 155 new_head += av->dccpav_buf_len; 156 } 157 158 av->dccpav_buf_head = new_head; 159 160 if (gap > 0) 161 memset(av->dccpav_buf + av->dccpav_buf_head + 1, 162 DCCP_ACKVEC_STATE_NOT_RECEIVED, gap); 163 164 av->dccpav_buf[av->dccpav_buf_head] = state; 165 av->dccpav_vec_len += packets; 166 return 0; 167 } 168 169 /* 170 * Implements the draft-ietf-dccp-spec-11.txt Appendix A 171 */ 172 int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk, 173 const u64 ackno, const u8 state) 174 { 175 /* 176 * Check at the right places if the buffer is full, if it is, tell the 177 * caller to start dropping packets till the HC-Sender acks our ACK 178 * vectors, when we will free up space in dccpav_buf. 179 * 180 * We may well decide to do buffer compression, etc, but for now lets 181 * just drop. 182 * 183 * From Appendix A: 184 * 185 * Of course, the circular buffer may overflow, either when the 186 * HC-Sender is sending data at a very high rate, when the 187 * HC-Receiver's acknowledgements are not reaching the HC-Sender, 188 * or when the HC-Sender is forgetting to acknowledge those acks 189 * (so the HC-Receiver is unable to clean up old state). In this 190 * case, the HC-Receiver should either compress the buffer (by 191 * increasing run lengths when possible), transfer its state to 192 * a larger buffer, or, as a last resort, drop all received 193 * packets, without processing them whatsoever, until its buffer 194 * shrinks again. 195 */ 196 197 /* See if this is the first ackno being inserted */ 198 if (av->dccpav_vec_len == 0) { 199 av->dccpav_buf[av->dccpav_buf_head] = state; 200 av->dccpav_vec_len = 1; 201 } else if (after48(ackno, av->dccpav_buf_ackno)) { 202 const u64 delta = dccp_delta_seqno(av->dccpav_buf_ackno, 203 ackno); 204 205 /* 206 * Look if the state of this packet is the same as the 207 * previous ackno and if so if we can bump the head len. 208 */ 209 if (delta == 1 && 210 dccp_ackvec_state(av, av->dccpav_buf_head) == state && 211 (dccp_ackvec_len(av, av->dccpav_buf_head) < 212 DCCP_ACKVEC_LEN_MASK)) 213 av->dccpav_buf[av->dccpav_buf_head]++; 214 else if (dccp_ackvec_set_buf_head_state(av, delta, state)) 215 return -ENOBUFS; 216 } else { 217 /* 218 * A.1.2. Old Packets 219 * 220 * When a packet with Sequence Number S arrives, and 221 * S <= buf_ackno, the HC-Receiver will scan the table 222 * for the byte corresponding to S. (Indexing structures 223 * could reduce the complexity of this scan.) 224 */ 225 u64 delta = dccp_delta_seqno(ackno, av->dccpav_buf_ackno); 226 unsigned int index = av->dccpav_buf_head; 227 228 while (1) { 229 const u8 len = dccp_ackvec_len(av, index); 230 const u8 state = dccp_ackvec_state(av, index); 231 /* 232 * valid packets not yet in dccpav_buf have a reserved 233 * entry, with a len equal to 0. 234 */ 235 if (state == DCCP_ACKVEC_STATE_NOT_RECEIVED && 236 len == 0 && delta == 0) { /* Found our 237 reserved seat! */ 238 dccp_pr_debug("Found %llu reserved seat!\n", 239 (unsigned long long)ackno); 240 av->dccpav_buf[index] = state; 241 goto out; 242 } 243 /* len == 0 means one packet */ 244 if (delta < len + 1) 245 goto out_duplicate; 246 247 delta -= len + 1; 248 if (++index == av->dccpav_buf_len) 249 index = 0; 250 } 251 } 252 253 av->dccpav_buf_ackno = ackno; 254 dccp_timestamp(sk, &av->dccpav_time); 255 out: 256 dccp_pr_debug(""); 257 return 0; 258 259 out_duplicate: 260 /* Duplicate packet */ 261 dccp_pr_debug("Received a dup or already considered lost " 262 "packet: %llu\n", (unsigned long long)ackno); 263 return -EILSEQ; 264 } 265 266 #ifdef CONFIG_IP_DCCP_DEBUG 267 void dccp_ackvector_print(const u64 ackno, const unsigned char *vector, int len) 268 { 269 if (!dccp_debug) 270 return; 271 272 printk("ACK vector len=%d, ackno=%llu |", len, 273 (unsigned long long)ackno); 274 275 while (len--) { 276 const u8 state = (*vector & DCCP_ACKVEC_STATE_MASK) >> 6; 277 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK; 278 279 printk("%d,%d|", state, rl); 280 ++vector; 281 } 282 283 printk("\n"); 284 } 285 286 void dccp_ackvec_print(const struct dccp_ackvec *av) 287 { 288 dccp_ackvector_print(av->dccpav_buf_ackno, 289 av->dccpav_buf + av->dccpav_buf_head, 290 av->dccpav_vec_len); 291 } 292 #endif 293 294 static void dccp_ackvec_trow_away_ack_record(struct dccp_ackvec *av) 295 { 296 /* 297 * As we're keeping track of the ack vector size (dccpav_vec_len) and 298 * the sent ack vector size (dccpav_sent_len) we don't need 299 * dccpav_buf_tail at all, but keep this code here as in the future 300 * we'll implement a vector of ack records, as suggested in 301 * draft-ietf-dccp-spec-11.txt Appendix A. -acme 302 */ 303 #if 0 304 av->dccpav_buf_tail = av->dccpav_ack_ptr + 1; 305 if (av->dccpav_buf_tail >= av->dccpav_vec_len) 306 av->dccpav_buf_tail -= av->dccpav_vec_len; 307 #endif 308 av->dccpav_vec_len -= av->dccpav_sent_len; 309 } 310 311 void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk, 312 const u64 ackno) 313 { 314 /* Check if we actually sent an ACK vector */ 315 if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1) 316 return; 317 318 if (ackno == av->dccpav_ack_seqno) { 319 #ifdef CONFIG_IP_DCCP_DEBUG 320 struct dccp_sock *dp = dccp_sk(sk); 321 const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ? 322 "CLIENT rx ack: " : "server rx ack: "; 323 #endif 324 dccp_pr_debug("%sACK packet 0, len=%d, ack_seqno=%llu, " 325 "ack_ackno=%llu, ACKED!\n", 326 debug_prefix, 1, 327 (unsigned long long)av->dccpav_ack_seqno, 328 (unsigned long long)av->dccpav_ack_ackno); 329 dccp_ackvec_trow_away_ack_record(av); 330 av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1; 331 } 332 } 333 334 static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av, 335 struct sock *sk, u64 ackno, 336 const unsigned char len, 337 const unsigned char *vector) 338 { 339 unsigned char i; 340 341 /* Check if we actually sent an ACK vector */ 342 if (av->dccpav_ack_seqno == DCCP_MAX_SEQNO + 1) 343 return; 344 /* 345 * We're in the receiver half connection, so if the received an ACK 346 * vector ackno (e.g. 50) before dccpav_ack_seqno (e.g. 52), we're 347 * not interested. 348 * 349 * Extra explanation with example: 350 * 351 * if we received an ACK vector with ackno 50, it can only be acking 352 * 50, 49, 48, etc, not 52 (the seqno for the ACK vector we sent). 353 */ 354 /* dccp_pr_debug("is %llu < %llu? ", ackno, av->dccpav_ack_seqno); */ 355 if (before48(ackno, av->dccpav_ack_seqno)) { 356 /* dccp_pr_debug_cat("yes\n"); */ 357 return; 358 } 359 /* dccp_pr_debug_cat("no\n"); */ 360 361 i = len; 362 while (i--) { 363 const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK; 364 u64 ackno_end_rl; 365 366 dccp_set_seqno(&ackno_end_rl, ackno - rl); 367 368 /* 369 * dccp_pr_debug("is %llu <= %llu <= %llu? ", ackno_end_rl, 370 * av->dccpav_ack_seqno, ackno); 371 */ 372 if (between48(av->dccpav_ack_seqno, ackno_end_rl, ackno)) { 373 const u8 state = (*vector & 374 DCCP_ACKVEC_STATE_MASK) >> 6; 375 /* dccp_pr_debug_cat("yes\n"); */ 376 377 if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) { 378 #ifdef CONFIG_IP_DCCP_DEBUG 379 struct dccp_sock *dp = dccp_sk(sk); 380 const char *debug_prefix = 381 dp->dccps_role == DCCP_ROLE_CLIENT ? 382 "CLIENT rx ack: " : "server rx ack: "; 383 #endif 384 dccp_pr_debug("%sACK vector 0, len=%d, " 385 "ack_seqno=%llu, ack_ackno=%llu, " 386 "ACKED!\n", 387 debug_prefix, len, 388 (unsigned long long) 389 av->dccpav_ack_seqno, 390 (unsigned long long) 391 av->dccpav_ack_ackno); 392 dccp_ackvec_trow_away_ack_record(av); 393 } 394 /* 395 * If dccpav_ack_seqno was not received, no problem 396 * we'll send another ACK vector. 397 */ 398 av->dccpav_ack_seqno = DCCP_MAX_SEQNO + 1; 399 break; 400 } 401 /* dccp_pr_debug_cat("no\n"); */ 402 403 dccp_set_seqno(&ackno, ackno_end_rl - 1); 404 ++vector; 405 } 406 } 407 408 int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb, 409 const u8 opt, const u8 *value, const u8 len) 410 { 411 if (len > DCCP_MAX_ACKVEC_LEN) 412 return -1; 413 414 /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */ 415 dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk, 416 DCCP_SKB_CB(skb)->dccpd_ack_seq, 417 len, value); 418 return 0; 419 } 420