| /* |
| * net/dccp/ackvec.c |
| * |
| * An implementation of Ack Vectors for the DCCP protocol |
| * Copyright (c) 2007 University of Aberdeen, Scotland, UK |
| * 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; |
| |
| struct dccp_ackvec *dccp_ackvec_alloc(const gfp_t priority) |
| { |
| struct dccp_ackvec *av = kmem_cache_zalloc(dccp_ackvec_slab, priority); |
| |
| if (av != NULL) { |
| av->av_buf_head = DCCPAV_MAX_ACKVEC_LEN - 1; |
| INIT_LIST_HEAD(&av->av_records); |
| } |
| return av; |
| } |
| |
| static void dccp_ackvec_purge_records(struct dccp_ackvec *av) |
| { |
| struct dccp_ackvec_record *cur, *next; |
| |
| list_for_each_entry_safe(cur, next, &av->av_records, avr_node) |
| kmem_cache_free(dccp_ackvec_record_slab, cur); |
| INIT_LIST_HEAD(&av->av_records); |
| } |
| |
| void dccp_ackvec_free(struct dccp_ackvec *av) |
| { |
| if (likely(av != NULL)) { |
| dccp_ackvec_purge_records(av); |
| kmem_cache_free(dccp_ackvec_slab, av); |
| } |
| } |
| |
| /** |
| * dccp_ackvec_update_records - Record information about sent Ack Vectors |
| * @av: Ack Vector records to update |
| * @seqno: Sequence number of the packet carrying the Ack Vector just sent |
| * @nonce_sum: The sum of all buffer nonces contained in the Ack Vector |
| */ |
| int dccp_ackvec_update_records(struct dccp_ackvec *av, u64 seqno, u8 nonce_sum) |
| { |
| struct dccp_ackvec_record *avr; |
| |
| avr = kmem_cache_alloc(dccp_ackvec_record_slab, GFP_ATOMIC); |
| if (avr == NULL) |
| return -ENOBUFS; |
| |
| avr->avr_ack_seqno = seqno; |
| avr->avr_ack_ptr = av->av_buf_head; |
| avr->avr_ack_ackno = av->av_buf_ackno; |
| avr->avr_ack_nonce = nonce_sum; |
| avr->avr_ack_runlen = dccp_ackvec_runlen(av->av_buf + av->av_buf_head); |
| /* |
| * Since GSS is incremented for each packet, the list is automatically |
| * arranged in descending order of @ack_seqno. |
| */ |
| list_add(&avr->avr_node, &av->av_records); |
| |
| dccp_pr_debug("Added Vector, ack_seqno=%llu, ack_ackno=%llu (rl=%u)\n", |
| (unsigned long long)avr->avr_ack_seqno, |
| (unsigned long long)avr->avr_ack_ackno, |
| avr->avr_ack_runlen); |
| return 0; |
| } |
| |
| /* |
| * 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 > DCCPAV_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, DCCPAV_NOT_RECEIVED, |
| gap + new_head + 1); |
| gap = -new_head; |
| } |
| new_head += DCCPAV_MAX_ACKVEC_LEN; |
| } |
| |
| av->av_buf_head = new_head; |
| |
| if (gap > 0) |
| memset(av->av_buf + av->av_buf_head + 1, |
| DCCPAV_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) |
| { |
| u8 *cur_head = av->av_buf + av->av_buf_head, |
| *buf_end = av->av_buf + DCCPAV_MAX_ACKVEC_LEN; |
| /* |
| * 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) { |
| *cur_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(cur_head) == state && |
| dccp_ackvec_runlen(cur_head) < DCCPAV_MAX_RUNLEN) |
| *cur_head += 1; |
| 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); |
| |
| while (1) { |
| const u8 len = dccp_ackvec_runlen(cur_head); |
| /* |
| * valid packets not yet in av_buf have a reserved |
| * entry, with a len equal to 0. |
| */ |
| if (*cur_head == DCCPAV_NOT_RECEIVED && delta == 0) { |
| dccp_pr_debug("Found %llu reserved seat!\n", |
| (unsigned long long)ackno); |
| *cur_head = state; |
| goto out; |
| } |
| /* len == 0 means one packet */ |
| if (delta < len + 1) |
| goto out_duplicate; |
| |
| delta -= len + 1; |
| if (++cur_head == buf_end) |
| cur_head = av->av_buf; |
| } |
| } |
| |
| av->av_buf_ackno = ackno; |
| 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 = DCCPAV_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(&avr->avr_node); |
| kmem_cache_free(dccp_ackvec_record_slab, 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), avr->avr_ack_runlen, |
| (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 = dccp_ackvec_runlen(vector); |
| 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)) { |
| if (dccp_ackvec_state(vector) != DCCPAV_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; |
| } |
| } |