/* * net/dccp/ackvec.c * * An implementation of the DCCP protocol * Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net> * * This program is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License as published by the * Free Software Foundation; version 2 of the License; */ #include "ackvec.h" #include "dccp.h" #include <linux/init.h> #include <linux/errno.h> #include <linux/kernel.h> #include <linux/skbuff.h> #include <linux/slab.h> #include <net/sock.h> static struct kmem_cache *dccp_ackvec_slab; static struct kmem_cache *dccp_ackvec_record_slab; static struct dccp_ackvec_record *dccp_ackvec_record_new(void) { struct dccp_ackvec_record *avr = kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC); if (avr != NULL) INIT_LIST_HEAD(&avr->avr_node); return avr; } static void dccp_ackvec_record_delete(struct dccp_ackvec_record *avr) { if (unlikely(avr == NULL)) return; /* Check if deleting a linked record */ WARN_ON(!list_empty(&avr->avr_node)); kmem_cache_free(dccp_ackvec_record_slab, avr); } static void dccp_ackvec_insert_avr(struct dccp_ackvec *av, struct dccp_ackvec_record *avr) { /* * AVRs are sorted by seqno. Since we are sending them in order, we * just add the AVR at the head of the list. * -sorbo. */ if (!list_empty(&av->av_records)) { const struct dccp_ackvec_record *head = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node); BUG_ON(before48(avr->avr_ack_seqno, head->avr_ack_seqno)); } list_add(&avr->avr_node, &av->av_records); } int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) { struct dccp_sock *dp = dccp_sk(sk); struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec; /* Figure out how many options do we need to represent the ackvec */ const u8 nr_opts = DIV_ROUND_UP(av->av_vec_len, DCCP_SINGLE_OPT_MAXLEN); u16 len = av->av_vec_len + 2 * nr_opts, i; u32 elapsed_time; const unsigned char *tail, *from; unsigned char *to; struct dccp_ackvec_record *avr; suseconds_t delta; if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) return -1; delta = ktime_us_delta(ktime_get_real(), av->av_time); elapsed_time = delta / 10; if (elapsed_time != 0 && dccp_insert_option_elapsed_time(sk, skb, elapsed_time)) return -1; avr = dccp_ackvec_record_new(); if (avr == NULL) return -1; DCCP_SKB_CB(skb)->dccpd_opt_len += len; to = skb_push(skb, len); len = av->av_vec_len; from = av->av_buf + av->av_buf_head; tail = av->av_buf + DCCP_MAX_ACKVEC_LEN; for (i = 0; i < nr_opts; ++i) { int copylen = len; if (len > DCCP_SINGLE_OPT_MAXLEN) copylen = DCCP_SINGLE_OPT_MAXLEN; *to++ = DCCPO_ACK_VECTOR_0; *to++ = copylen + 2; /* Check if buf_head wraps */ if (from + copylen > tail) { const u16 tailsize = tail - from; memcpy(to, from, tailsize); to += tailsize; len -= tailsize; copylen -= tailsize; from = av->av_buf; } memcpy(to, from, copylen); from += copylen; to += copylen; len -= copylen; } /* * From RFC 4340, A.2: * * For each acknowledgement it sends, the HC-Receiver will add an * acknowledgement record. ack_seqno will equal the HC-Receiver * sequence number it used for the ack packet; ack_ptr will equal * buf_head; ack_ackno will equal buf_ackno; and ack_nonce will * equal buf_nonce. */ avr->avr_ack_seqno = DCCP_SKB_CB(skb)->dccpd_seq; avr->avr_ack_ptr = av->av_buf_head; avr->avr_ack_ackno = av->av_buf_ackno; avr->avr_ack_nonce = av->av_buf_nonce; avr->avr_sent_len = av->av_vec_len; dccp_ackvec_insert_avr(av, avr); dccp_pr_debug("%s ACK Vector 0, len=%d, ack_seqno=%llu, " "ack_ackno=%llu\n", dccp_role(sk), avr->avr_sent_len, (unsigned long long)avr->avr_ack_seqno, (unsigned long long)avr->avr_ack_ackno); return 0; } struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority) { struct dccp_ackvec *av = kmem_cache_alloc(dccp_ackvec_slab, priority); if (av != NULL) { av->av_buf_head = DCCP_MAX_ACKVEC_LEN - 1; av->av_buf_ackno = UINT48_MAX + 1; av->av_buf_nonce = 0; av->av_time = ktime_set(0, 0); av->av_vec_len = 0; INIT_LIST_HEAD(&av->av_records); } return av; } void dccp_ackvec_free(struct dccp_ackvec *av) { if (unlikely(av == NULL)) return; if (!list_empty(&av->av_records)) { struct dccp_ackvec_record *avr, *next; list_for_each_entry_safe(avr, next, &av->av_records, avr_node) { list_del_init(&avr->avr_node); dccp_ackvec_record_delete(avr); } } kmem_cache_free(dccp_ackvec_slab, av); } static inline u8 dccp_ackvec_state(const struct dccp_ackvec *av, const u32 index) { return av->av_buf[index] & DCCP_ACKVEC_STATE_MASK; } static inline u8 dccp_ackvec_len(const struct dccp_ackvec *av, const u32 index) { return av->av_buf[index] & DCCP_ACKVEC_LEN_MASK; } /* * If several packets are missing, the HC-Receiver may prefer to enter multiple * bytes with run length 0, rather than a single byte with a larger run length; * this simplifies table updates if one of the missing packets arrives. */ static inline int dccp_ackvec_set_buf_head_state(struct dccp_ackvec *av, const unsigned int packets, const unsigned char state) { unsigned int gap; long new_head; if (av->av_vec_len + packets > DCCP_MAX_ACKVEC_LEN) return -ENOBUFS; gap = packets - 1; new_head = av->av_buf_head - packets; if (new_head < 0) { if (gap > 0) { memset(av->av_buf, DCCP_ACKVEC_STATE_NOT_RECEIVED, gap + new_head + 1); gap = -new_head; } new_head += DCCP_MAX_ACKVEC_LEN; } av->av_buf_head = new_head; if (gap > 0) memset(av->av_buf + av->av_buf_head + 1, DCCP_ACKVEC_STATE_NOT_RECEIVED, gap); av->av_buf[av->av_buf_head] = state; av->av_vec_len += packets; return 0; } /* * Implements the RFC 4340, Appendix A */ int dccp_ackvec_add(struct dccp_ackvec *av, const struct sock *sk, const u64 ackno, const u8 state) { /* * Check at the right places if the buffer is full, if it is, tell the * caller to start dropping packets till the HC-Sender acks our ACK * vectors, when we will free up space in av_buf. * * We may well decide to do buffer compression, etc, but for now lets * just drop. * * From Appendix A.1.1 (`New Packets'): * * Of course, the circular buffer may overflow, either when the * HC-Sender is sending data at a very high rate, when the * HC-Receiver's acknowledgements are not reaching the HC-Sender, * or when the HC-Sender is forgetting to acknowledge those acks * (so the HC-Receiver is unable to clean up old state). In this * case, the HC-Receiver should either compress the buffer (by * increasing run lengths when possible), transfer its state to * a larger buffer, or, as a last resort, drop all received * packets, without processing them whatsoever, until its buffer * shrinks again. */ /* See if this is the first ackno being inserted */ if (av->av_vec_len == 0) { av->av_buf[av->av_buf_head] = state; av->av_vec_len = 1; } else if (after48(ackno, av->av_buf_ackno)) { const u64 delta = dccp_delta_seqno(av->av_buf_ackno, ackno); /* * Look if the state of this packet is the same as the * previous ackno and if so if we can bump the head len. */ if (delta == 1 && dccp_ackvec_state(av, av->av_buf_head) == state && dccp_ackvec_len(av, av->av_buf_head) < DCCP_ACKVEC_LEN_MASK) av->av_buf[av->av_buf_head]++; else if (dccp_ackvec_set_buf_head_state(av, delta, state)) return -ENOBUFS; } else { /* * A.1.2. Old Packets * * When a packet with Sequence Number S <= buf_ackno * arrives, the HC-Receiver will scan the table for * the byte corresponding to S. (Indexing structures * could reduce the complexity of this scan.) */ u64 delta = dccp_delta_seqno(ackno, av->av_buf_ackno); u32 index = av->av_buf_head; while (1) { const u8 len = dccp_ackvec_len(av, index); const u8 av_state = dccp_ackvec_state(av, index); /* * valid packets not yet in av_buf have a reserved * entry, with a len equal to 0. */ if (av_state == DCCP_ACKVEC_STATE_NOT_RECEIVED && len == 0 && delta == 0) { /* Found our reserved seat! */ dccp_pr_debug("Found %llu reserved seat!\n", (unsigned long long)ackno); av->av_buf[index] = state; goto out; } /* len == 0 means one packet */ if (delta < len + 1) goto out_duplicate; delta -= len + 1; if (++index == DCCP_MAX_ACKVEC_LEN) index = 0; } } av->av_buf_ackno = ackno; av->av_time = ktime_get_real(); out: return 0; out_duplicate: /* Duplicate packet */ dccp_pr_debug("Received a dup or already considered lost " "packet: %llu\n", (unsigned long long)ackno); return -EILSEQ; } static void dccp_ackvec_throw_record(struct dccp_ackvec *av, struct dccp_ackvec_record *avr) { struct dccp_ackvec_record *next; /* sort out vector length */ if (av->av_buf_head <= avr->avr_ack_ptr) av->av_vec_len = avr->avr_ack_ptr - av->av_buf_head; else av->av_vec_len = DCCP_MAX_ACKVEC_LEN - 1 - av->av_buf_head + avr->avr_ack_ptr; /* free records */ list_for_each_entry_safe_from(avr, next, &av->av_records, avr_node) { list_del_init(&avr->avr_node); dccp_ackvec_record_delete(avr); } } void dccp_ackvec_check_rcv_ackno(struct dccp_ackvec *av, struct sock *sk, const u64 ackno) { struct dccp_ackvec_record *avr; /* * If we traverse backwards, it should be faster when we have large * windows. We will be receiving ACKs for stuff we sent a while back * -sorbo. */ list_for_each_entry_reverse(avr, &av->av_records, avr_node) { if (ackno == avr->avr_ack_seqno) { dccp_pr_debug("%s ACK packet 0, len=%d, ack_seqno=%llu, " "ack_ackno=%llu, ACKED!\n", dccp_role(sk), 1, (unsigned long long)avr->avr_ack_seqno, (unsigned long long)avr->avr_ack_ackno); dccp_ackvec_throw_record(av, avr); break; } else if (avr->avr_ack_seqno > ackno) break; /* old news */ } } static void dccp_ackvec_check_rcv_ackvector(struct dccp_ackvec *av, struct sock *sk, u64 *ackno, const unsigned char len, const unsigned char *vector) { unsigned char i; struct dccp_ackvec_record *avr; /* Check if we actually sent an ACK vector */ if (list_empty(&av->av_records)) return; i = len; /* * XXX * I think it might be more efficient to work backwards. See comment on * rcv_ackno. -sorbo. */ avr = list_entry(av->av_records.next, struct dccp_ackvec_record, avr_node); while (i--) { const u8 rl = *vector & DCCP_ACKVEC_LEN_MASK; u64 ackno_end_rl; dccp_set_seqno(&ackno_end_rl, *ackno - rl); /* * If our AVR sequence number is greater than the ack, go * forward in the AVR list until it is not so. */ list_for_each_entry_from(avr, &av->av_records, avr_node) { if (!after48(avr->avr_ack_seqno, *ackno)) goto found; } /* End of the av_records list, not found, exit */ break; found: if (between48(avr->avr_ack_seqno, ackno_end_rl, *ackno)) { const u8 state = *vector & DCCP_ACKVEC_STATE_MASK; if (state != DCCP_ACKVEC_STATE_NOT_RECEIVED) { dccp_pr_debug("%s ACK vector 0, len=%d, " "ack_seqno=%llu, ack_ackno=%llu, " "ACKED!\n", dccp_role(sk), len, (unsigned long long) avr->avr_ack_seqno, (unsigned long long) avr->avr_ack_ackno); dccp_ackvec_throw_record(av, avr); break; } /* * If it wasn't received, continue scanning... we might * find another one. */ } dccp_set_seqno(ackno, ackno_end_rl - 1); ++vector; } } int dccp_ackvec_parse(struct sock *sk, const struct sk_buff *skb, u64 *ackno, const u8 opt, const u8 *value, const u8 len) { if (len > DCCP_SINGLE_OPT_MAXLEN) return -1; /* dccp_ackvector_print(DCCP_SKB_CB(skb)->dccpd_ack_seq, value, len); */ dccp_ackvec_check_rcv_ackvector(dccp_sk(sk)->dccps_hc_rx_ackvec, sk, ackno, len, value); return 0; } int __init dccp_ackvec_init(void) { dccp_ackvec_slab = kmem_cache_create("dccp_ackvec", sizeof(struct dccp_ackvec), 0, SLAB_HWCACHE_ALIGN, NULL); if (dccp_ackvec_slab == NULL) goto out_err; dccp_ackvec_record_slab = kmem_cache_create("dccp_ackvec_record", sizeof(struct dccp_ackvec_record), 0, SLAB_HWCACHE_ALIGN, NULL); if (dccp_ackvec_record_slab == NULL) goto out_destroy_slab; return 0; out_destroy_slab: kmem_cache_destroy(dccp_ackvec_slab); dccp_ackvec_slab = NULL; out_err: DCCP_CRIT("Unable to create Ack Vector slab cache"); return -ENOBUFS; } void dccp_ackvec_exit(void) { if (dccp_ackvec_slab != NULL) { kmem_cache_destroy(dccp_ackvec_slab); dccp_ackvec_slab = NULL; } if (dccp_ackvec_record_slab != NULL) { kmem_cache_destroy(dccp_ackvec_record_slab); dccp_ackvec_record_slab = NULL; } }